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At least 271 records · Page 15Linked to original sources
PubMed1995

The contribution of perivascular tissue to the neovascularization of full thickness skin grafts (prefabricated flaps): an experimental study.

The effect of varying amounts of perivascular tissue on the neovascularisation of full thickness skin grafts (prefabricated flaps) in rats was investigated. The femoral vasculature of adult Wistar rats (n = 48) was dissected to varying degrees: Group 1, perivascular areolar tissue and preadventitial tissue preserved; Group 2, perivascular areolar tissue removed, periadventitial tissue preserved; Group 3, femoral artery and vein skeletonised. Full thickness skin grafts harvested from the abdomen were laid on the femoral vessels. Silicone sheets were used to isolate the graft and its vascular supply from the surrounding tissue bed. At set times, from 24 h to 7 days, grafts from each group were harvested and the amount of neovascularisation was evaluated histologically. None of the grafts developed necrosis and all of them showed a progressive degree of neovascularisation. Using chi-square analysis, our study found no evidence that varying the amount of perivascular tissue significantly affected the degree of neovascularisation. In all 3 groups, the degree of neovascularisation was significantly improved over time (p = 0.002).

Analysis of Variance↗
PubMed2006

Primer: tissue fixation and preservation for optimal molecular analysis of urologic tissues.

Appreciation of the different methods of tissue handling is a prerequisite to obtaining accurate and biologically relevant tissue-based information. When a tissue sample is removed from its environment, biological changes are induced within its constituent cell population. It is inevitable that artefacts will be induced through obtaining and processing tissues, irrespective of whether the samples comprise a few cells derived by fine-needle aspiration or larger specimens obtained surgically. Depending upon the level of sophistication of the analytical methods subsequently employed, such changes might be irrelevant, or might result in acquisition of spurious data. While even brief ischemia alters expression of some genes, detectable by appropriate molecular techniques, the same changes might make no appreciable difference to tissue histomorphology. Furthermore, the phenotype of viable cells is known to change during tissue collection and handling. For example, transitional epithelial cells voided in urine are not phenotypically identical to those retained within the urothelium. Such phenotypic changes are temporary and might be of little consequence to subsequent analyses. Surprisingly, many cells in tissues preserved in an ischemic state can remain viable for several hours, and are believed to remain genotypically stable in the short term.

Alcohols↗
PubMed2001

Primary and recombinant HIV type 1 strains resistant to protease inhibitors are pathogenic in mature human lymphoid tissues.

Preserved peripheral CD4+ T cell counts despite virologic failure in patients undergoing protease inhibitor (PI)-containing antiviral regimens are a frequent occurrence in human immunodeficiency virus (HIV) disease. One hypothesis to explain the relative sparing of CD4+ T cells is that HIV strains exhibiting PI resistance concomitantly are attenuated in terms of cytopathicity for mature T cells. To test this hypothesis, we used a three-dimensional human tonsil histoculture microenvironment to assess the pathogenic potential of a panel of primary and recombinant HIV-1 strains derived from patients experiencing PI failure. All the viruses tested replicated efficiently in these cultures and, in some cases, better than comparable wild-type viral isolates. Furthermore, the PI-resistant strains depleted CD4+ T cells potently and comparably with wild-type isolates in these ex vivo lymphoid tissues. These results demonstrate that PI-resistant viruses are not inherently less pathogenic for mature T cells. Therefore, the sustained peripheral lymphocyte counts in patients with selective virologic failure may be due to specific defects in viral replication in other cell compartments or to an undefined host adaptation to viral infection during PI therapy.

CD4-Positive T-Lymphocytes↗
PubMedDate not supplied

Microwave fixation provides excellent preservation of tissue, cells and antigens for light and electron microscopy.

It was demonstrated that microwave energy used simultaneously in combination with low concentrations of glutaraldehyde (0.05%) and formaldehyde (2.0%) rapidly preserved light microscopic histology and excellent fine structural details, as well as a variety of cytoplasmic and membrane-bound antigens. Specimen blocks up to 1 cm3 can be fixed in as brief a time as 26 ms using a specially designed microwave device (ultrafast microwave fixation method). The fast microwave fixation method, using a commercially available device, was successfully used to preserve granule-bound rat mast cell chymase which was subsequently detected by a postembedding immunogold procedure. Control of the following parameters is important to the microwave fixation method: (1) specimens with one dimension less than 1 cm; (2) irradiation temperatures lower than 50 degrees C; (3) irradiation times less than 50 s; (4) immediate replacement of the postirradiation solution with cold storage buffer; (5) fixing the specimen within 15 min after it is removed from its blood supply.

Animals↗
PubMed1992

Durability of glutaraldehyde-fixed pericardial valve prostheses: clinical and animal experimental studies.

Bovine pericardium has been widely employed as a xenograft tissue for the manufacture of bioprosthetic valve substitutes. Early three-leaflet valve models showed poor tissue preservation and shortcomings in valve design, which accounted for tissue wear and prosthesis failure due to cuspal tear. Reducing the number of cusps in the unicusp pericardial valve has proved unsuccessful due to stretching of the single pericardial leaflet with consequent valvular incompetence. The new generation of pericardial xenografts present basic changes in valve design and optimal tissue preservation after industrial processing, with no evidence of leaflet tear at medium term follow up. However, clinical experience is limited and, similarly to porcine xenografts, dystrophic calcification still appears to be a major problem.

Adult↗
PubMed2004

Reactive astrocytes protect tissue and preserve function after spinal cord injury.

Reactive astrocytes are prominent in the cellular response to spinal cord injury (SCI), but their roles are not well understood. We used a transgenic mouse model to study the consequences of selective and conditional ablation of reactive astrocytes after stab or crush SCI. Mice expressing a glial fibrillary acid protein-herpes simplex virus-thymidine kinase transgene were given mild or moderate SCI and treated with the antiviral agent ganciclovir (GCV) to ablate dividing, reactive, transgene-expressing astrocytes in the immediate vicinity of the SCI. Small stab injuries in control mice caused little tissue disruption, little demyelination, no obvious neuronal death, and mild, reversible functional impairments. Equivalent small stab injuries in transgenic mice given GCV to ablate reactive astrocytes caused failure of blood-brain barrier repair, leukocyte infiltration, local tissue disruption, severe demyelination, neuronal and oligodendrocyte death, and pronounced motor deficits. Moderate crush injuries in control mice caused focal tissue disruption and cellular degeneration, with moderate, primarily reversible motor impairments. Equivalent moderate crush injuries combined with ablation of reactive astrocytes caused widespread tissue disruption, pronounced cellular degeneration, and failure of wound contraction, with severe persisting motor deficits. These findings show that reactive astrocytes provide essential activities that protect tissue and preserve function after mild or moderate SCI. In nontransgenic animals, crush or contusion SCIs routinely exhibit regions of degenerated tissue that are devoid of astrocytes. Our findings suggest that identifying ways to preserve reactive astrocytes, to augment their protective functions, or both, may lead to novel approaches to reducing secondary tissue degeneration and improving functional outcome after SCI.

Animals↗
PubMed1985

Metroplasty and myomectomy with the CO2 laser for maximizing the preservation of normal tissue and minimizing blood loss.

A study was designed to evaluate the efficacy of the CO2 laser in performing conservative uterine surgery, metroplasty and myomectomy; to determine blood loss using this technique; and to ascertain how much normal uterine tissue was preserved. To assess the effectiveness of this new surgical technique, 22 patients underwent metroplasty, myomectomy or both utilizing the CO2 laser. The blood loss via microlaser surgery was compared to that in a group of 14 patients who underwent conventional surgery. The initial findings indicated that the CO2 laser is a viable surgical instrument for myomectomy and metroplasty and that its use yields less blood loss and greater preservation of normal tissue.

Adult↗
PubMed1975

[Supramolecular changes in preserved corneal tissue exposed to alpha-tocopherol].

Kinetics of chemifluorescence of the tissue of the cornea of isolated dog eyes (induced by 1% hydrogen peroxide) was confronted to the results of determination of the ultrastructural changes in the 30th day the eye preservation in a moist chamber at 4 degrees C with and without replacement of the chamber humour of the eye with alpha-tocopherol. The results of investigations pointed to profound changes of free radical processes in the structural components of the corneal cells with changes in the periods and conditions of preservation. It is supposed that these disturbances underlied the trigger mechanisms of the autolysis. Stabilization of the lipoprotein complexes of the cell in preservation is apparently determined by the capacity of antioxidants, particularly of alpha-tocopherol to maintain oxidative processes at a constant level.

Animals↗
PubMed1987

Treatment of central corneal ulcers by à chaud transplantation of organ culture preserved donor tissue.

In the period 1979-83 a total of 232 penetrating corneal transplantations were performed with organ culture preserved donor material. Forty-two operations were made à chaud for central corneal ulcerations. The results of these interventions are reported and discussed. The surgery presented no serious problems and on first post-operative day the anterior chamber was reformed in all cases, and pain was relieved. Patients were confined to bed only for 1 day. Graft deswelling was slightly retarded compared to planned surgery, but all functioning grafts obtained normal thickness. The overall graft survival rates after 6, 12 and 18 months were 66, 53 and 48%, respectively. For herpetic ulcers the survival after 18 months was 49% and for non-herpetic ulcers 47%. The grafts failed in all cases where it had been necessary to employ grafts of more than 10 mm. This latter group was comprised of the non-herpetic cases; were they excluded, the graft survival rate would increase to 60%. Among cases with a clear graft the median visual acuity after 18 months was 0.33 (range less than 0.1-0.67). Excluding cases with a non-corneal cause of visual reduction, the median visual acuity was 0.4 (range 0.33-0.67). It is concluded that grafting can be successfully employed in the treatment of central ulcers, as it not only restitutes tissue integrity, but also preserves useful vision.

Adolescent↗
PubMed1992

Role of the frozen tissue bank in molecular pathology.

The new discipline of molecular pathology requires that high-quality, intact genomic DNA, mRNA, and proteins be available from frozen tissue samples. It is now necessary for pathology laboratories to establish consistent guidelines for the preparation and storage of frozen tissue samples in order to have properly preserved tissues available for diagnostic molecular techniques. Maintaining a frozen tissue bank requires a pathologist to oversee this program and to integrate it into the routine surgical pathology activities. A member of the laboratory technical staff can serve as a tissue bank coordinator and have responsibility for preparation of tissue samples, their systematic storage and retrieval, and routine maintenance of equipment and supplies. Tissue sampling must be done as soon as possible after excision of the specimen and is the responsibility of a qualified pathologist. The samples may be snap frozen without cryoprotection at -78 degrees C or colder for subsequent use in procedures requiring the extraction of genomic DNA, mRNA, or protein. To preserve tissue architecture and cytologic features for immunohistochemistry and in situ hybridization, the tissue should be frozen at -78 degrees C or colder with a cryoprotectant such as OCT. Long-term storage of the frozen tissue is recommended at -140 degrees C or colder in a locked liquid nitrogen freezer, and the record of sample inventory can easily be kept in a computerized database. Tissues sampled and stored under these conditions have been used successfully in a wide variety of molecular techniques. In addition to malignant tumor tissue, samples from benign lesions and normal tissues should be frozen.(ABSTRACT TRUNCATED AT 250 WORDS)

Cryopreservation↗
PubMed2003

Dose-dependent protection of cardiac function by propofol during ischemia and early reperfusion in rats: effects on 15-F2t-isoprostane formation.

We examined the effects of propofol (2,6-diisopropylphenol) on functional recovery and 15-F2t-isoprostane generation during ischemia-reperfusion in Langendorff-perfused rat hearts. Before the induction of 40 min of global ischemia, hearts were perfused (10 min) with propofol at 5 (lo-P) or 12 microg/mL (hi-P) in saline or with saline only (control). During ischemia, saline, lo-P, or hi-P was perfused through the aorta at 60 microL/min. During the first 15 min of reperfusion, propofol (5 or 12 microg/mL) was continued, followed by perfusion with 5 microg/mL propofol for 75 min in both propofol-treated groups. After 90 min of reperfusion (Rep-90), heart tissues were harvested for assessment of antioxidant status. In hi-P, we observed increased latency to and greater reduction of ischemic contracture relative to the lo-P or control groups. 15-F2t-Isoprostane concentrations increased during ischemia and were significantly lower in hi-P and lo-P than in control (P < 0.01). At Rep-90, myocardial functional recovery was greater in both propofol-treated groups relative to control, and it correlated positively with tissue antioxidant capacity preservation. Tissue antioxidant capacity was better preserved in hi-P than in lo-P treatment (P < 0.05). We conclude that oxidant injury occurs during ischemia and reperfusion, and propofol provides dose-dependent protection primarily by enhancing tissue antioxidant capacity and reducing lipid peroxidation.

Anesthetics, Intravenous↗
PubMed2000

Bombesin recovers gut-associated lymphoid tissue and preserves immunity to bacterial pneumonia in mice receiving total parenteral nutrition.

OBJECTIVE: To study the ability of bombesin (BBS) to recover gut-associated lymphoid tissue (GALT) and preserve immunity in a lethal model of Pseudomonas aeruginosa (Ps) pneumonia in mice receiving total parenteral nutrition (TPN). SUMMARY BACKGROUND DATA: TPN causes depression of mucosal immunity compared with enterally fed animals, which may explain the increased incidence of pneumonia in parenterally fed trauma patients. BBS prevents this TPN-induced GALT atrophy, depressed gastrointestinal and respiratory tract IgA levels, and impaired antiviral IgA-mediated mucosal immunity. The authors examined whether some supplement could be added to TPN to avoid this GALT atrophy and lower the incidence of infectious complications in the parenterally fed animal. METHODS: Male mice were randomized to chow or intravenous (IV) TPN. After 5 days of IV TPN, mice received 0, 1, 2, or 3 days of BBS IV three times a day and then were killed to harvest Peyer's patch, intraepithelium, and lamina propria for cell yields. Gastrointestinal and respiratory tract IgA levels were analyzed by enzyme-linked immunosorbent assay. Next, mice underwent intranasal inoculation with liposomes alone (nonimmune) or liposome-containing Ps polysaccharide. Ps immune mice were catheterized and randomized to chow, IV TPN, or IV TPN + BBS. The liposome group received chow but no IV catheter. These mice were given an LD90 dose of intratracheal Ps, and death rates were recorded. RESULTS: GALT and gastrointestinal and respiratory tract IgA levels improved to those in chow-fed mice after 3 days of BBS. Immunization reduced the death rate from 92% in chow-fed liposome-only animals to 20% in immunized animals. TPN-fed animals lost their mucosal immunity, with a death rate of 86% compared with 21% in the TPN + BBS group. CONCLUSION: The results demonstrate that BBS reverses TPN-induced changes in GALT and preserves mucosal immunity. Ps immunization reduces the death rate in a gram-negative pneumonia model and maintains gastrointestinal and respiratory immunity in Ps immune mice receiving IV TPN.

Animals↗
PubMed1979

Donor cornea contamination with McCarey-Kaufman medium preservation.

A patient had corneal infection with Staphylococcus aureus after keratoplasty from tissue preserved in McCarey-Kaufman medium. The small, successfully treated corneal infection was from the same organism cultured from the tissue culture medium at the time of transplantation. Possible sources of donor-tissue contamination included the increase in ocular flora seen in postmortem eyes, blood-borne bacteria, lack of sterile technique in securing donor tissue, inadequate irrigation of the tissue, and inadequate use of topical antibiotics on the tissue. Preservation medium and specimens from medium-preserved and refrigerated corneas should be cultured before and during surgery.

Administration, Topical↗
PubMed1993

Effects of ischemia and reperfusion on intrinsic vascular regulation in the postnatal intestinal circulation.

The purpose of these experiments was to determine the effect of 1 h of total ischemia followed by 2 h of reperfusion on intrinsic vascular regulation within intestine from 3- and 35-d-old swine. Intrinsic vascular regulation was defined as the ability of in vitro segments of small intestine to bring about adjustments of blood flow and the arteriovenous O2 content difference across the intestinal segment of sufficient magnitude to preserve tissue O2 uptake in response to a 35% reduction in arterial perfusion pressure. This response was elicited before (control conditions) and after ischemia-reperfusion (post-I/R). In older subjects, the efficacy of blood flow regulation was attenuated post-I/R, insofar as blood flow fell in response to pressure reduction. However, this group demonstrated a rise in arteriovenous content difference after pressure reduction under control and post-I/R conditions that were of sufficient magnitude to preserve tissue O2 uptake. In younger subjects, blood flow regulation was absent under control conditions and post-I/R. The arteriovenous O2 content difference increased in response to pressure reduction under control conditions but failed to do so post-I/R; consequently, tissue oxygenation decreased in response to arterial pressure reduction post-I/R in 3-d-old intestine. We conclude that ischemia-reperfusion affects intrinsic vascular regulation in postnatal intestine and that this effect is age-dependent. Intestine from older subjects maintains the intrinsic capacity to preserve tissue oxygenation in response to a hypotensive challenge despite the insult of ischemia-reperfusion, whereas intestine from younger subjects does not maintain this capacity.

Animals↗