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At least 271 records · Page 15Linked to original sources
PubMedDate not supplied

Open aortic bioprosthesis at zero pressure. A new concept in glutaraldehyde fixation of tissue valve.

An experimental trial has been made to fix a porcine aortic valve in a semi-open position using 1 percent glutaraldehyde (open model). Four valves of open model xenograft were examined with use of our pulse-simulator. Four valves fixed in the closed position (closed model) and one untreated valve were studied for comparison. Comparison of the opening characteristics at the pump pressure of 120 gr/sq.cm revealed the significant difference in that the open model valves gave the simultaneous cusp opening with a circular orifice, while the closed model valves opened in sequence with irregular orifice. This relationship was substantiated by forward flow measurement. Analysis of the flow velocity curve confirmed the competence of the open model xenograft. These results suggest that the open aortic bioprosthesis may provide an improved hemodynamic function under low flow conditions.

Aortic Valve↗
PubMed1984

Fixation, decalcification, and tissue processing effects on articular cartilage proteoglycans.

Neutral buffered 4% formaldehyde fixation for 48 h preserved well the proteoglycan content of bovine articular cartilage. Neither subsequent demineralization in 10% EDTA, nor light microscopic tissue processing, reduced the hexosamine or uronic acid content of the tissue. Fixation in alcoholic solutions increased Safranin O binding as well as periodic acid Schiff reaction of the cartilage matrix as measured by microspectrophotometry. It is suggested that the enhanced staining of cartilage was due to better preservation of the glycoprotein oligosaccharides. Quaternary ammonium salts in the fixative suppressed the staining of cartilage matrix with Safranin O.

Animals↗
PubMed1984

Determination of protein loss during aqueous and phase partition fixation using formalin and glutaraldehyde.

In phase partition fixation tissue is immersed in an organic solvent at equilibrium with an aqueous phase containing a fixing agent. By using radioisotope labeling techniques the effects of phase partition fixation on protein retention during fixation of tissue with formalin and glutaraldehyde have been determined and compared with those of standard aqueous fixation using these fixatives. It has been shown that retention of protein in tissue during phase partition fixation was as good or better than during aqueous fixation. Improved retention provides further evidence that phase partition fixation may be a useful alternative to aqueous fixation.

Animals↗
PubMed1998

Mohs micrographic surgery.

Mohs micrographic surgery (MMS) is a specialized type of minimal marginal surgery that offers cure rates superior to other options in the treatment of contiguous skin cancers in selected settings. Developed by Dr. Frederic E. Mohs, the technique originally required in situ tissue fixation before excision. Most Mohs micrographic surgeons now use the fresh tissue technique exclusively. Horizontal frozen histologic sections of the excised tumor permit more complete microscopic examination of the surgical margin than traditional methods. Residual tumor is graphically mapped and malignant extensions are pursued with staged excisions until the tumor is removed. Maximum sparing of tumor-free adjacent tissue is achieved with histologic mapping of the tumor boundaries, thus optimizing subsequent wound reconstruction. The history, techniques, indications, cure rates, and current controversies of MMS are reviewed.

Carcinoma↗
PubMed2005

Skin wound closure with a novel shape-memory alloy fixator.

BACKGROUND: Previously, we have described novel, thermally deployable tissue fixators based on the shape-memory properties of nickel titanium. The present study reports on the in vivo wound closure with these fixators as a preliminary to evaluating their use for bowel anastomoses. METHODS: Twenty adult Sprague-Dawley rats had 2.0-cm dorsal skin incisions approximated either with shape-memory alloy (SMA) fixators or conventional skin staples on a random basis. Electrical resistance heating was used to transform and deploy the SMA fixators into the wound. The rats were killed on day 14 or day 28 and wound specimens were harvested for force distraction studies and histologic examination. RESULTS: There was no incidence of wound dehiscence. 14- and 28-day wounds from both groups showed no significant difference in breaking force or energy. Histology revealed appropriate stages of wound healing for both SMA-closed and control wounds. CONCLUSIONS: The results confirm the efficacy and safety of tissue-edge approximation with SMA fixators.

Alloys↗
PubMed1994

Drug-induced intralysosomal storage of sulfated glycosaminoglycans (GAGs): a methodical pitfall occurring with acridine derivatives.

The present communication deals with an adverse drug action which is exerted by a series of dicationic amphiphilic compounds such as the immunomodulatory drug tilorone and congeners. The drugs induce lysosomal storage of sulfated glycosaminoglycans (GAGs) in intact organisms and in cultured cells by impairing the lysosomal GAG degradation. This impairment was proposed to be due to the formation of non-degradable GAG-drug complexes. GAGs are highly water-soluble and not preservable by aldehyde fixatives. Therefore, usually the lysosomes appear optically empty in histological preparations, unless the fixative is supplemented with a GAG-precipitating agent. When acridine derivatives were used for the induction of GAG-storage, the lysosomal storage material displayed unexpected and unsystematic variability with regard to its preservability and ultrastructure. In the present study, evidence is presented that the acridine derivatives (a) remain bound to the stored GAGs for some time after glutaraldehyde fixation; and (b) they precipitate GAGs in vitro. Thus, apart from their unwanted action in the living cell, i.e., disturbing lysosomal GAG-degradation, the drugs function as precipitants and "fixatives" for the intralysosomal GAGs. The uncontrolled persistence of the drugs after tissue fixation leads to variable degree of GAG-preservation and thus to unpredictable variability of the ultrastructure of the storage lysosomes. If this pitfall is not realized, the resulting inconsistencies may rise confusion among toxicologic pathologists who deal with drug-induced lysosomal storage disorders.

Acridines↗
PubMed1995

Detection and sequence confirmation of Sin Nombre virus RNA in paraffin-embedded human tissues using one-step RT-PCR.

Sin Nombre virus (SNV) is the causative agent of hantavirus pulmonary syndrome (HPS). SNV RNA can be detected in fresh or frozen autopsy tissue samples by reverse transcriptase polymerase chain reaction (RT-PCR), and virus antigens can be identified by immunohistochemistry. A method was developed for demonstration of SNV RNA in formalin-fixed, paraffin-embedded tissues by RT-PCR. Virus genomes were detected in 8 of 12 (66.7%) fixed human tissue samples that were positive by immunohistochemistry, and RT-PCR prior to tissue fixation. By comparison with nucleotide sequences determined previously in fresh or frozen tissues of the same patients, identical genomic sequences were obtained, proving the authenticity of the PCR products. The study demonstrates that detection of SNV RNA in formalin-fixed, paraffin-embedded archival tissue by RT-PCR is feasible. This method allows retrospective studies on the phylogenetic epidemiology of SNV in North America.

Base Sequence↗
PubMed1992

In situ hybridisation: principles and applications.

In situ hybridisation (ISH) is based on the complementary pairing of labelled DNA or RNA probes with normal or abnormal nucleic acid sequences in intact chromosomes, cells or tissue sections. Compared with other molecular biology techniques applicable to anatomical pathology, ISH enjoys better rapport with histopathologists because of its similarity to immunohistochemistry. It has the unique advantage over other molecular biology techniques--largely based on probe hybridisation with nucleic acid extracted from homogenised tissue samples--of allowing localisation and visualisation of target nucleic acid sequences within morphologically identifiable cells or cellular structures. Probes for ISH may bear radioactive or non-radioactive labels. Isotopic probes (3H, 32P, 35S, 125I) are generally more sensitive than non-isotopic ones but are less stable, require longer processing times and stringent disposal methods. Numerous non-isotopic labels have been used; of these biotin and digoxigenin are the reporters of choice. Optimised non-isotopic systems of equivalent sensitivity to those which use radioactive-labelled probes have been described. In ISH, finding the optimal balance between good morphological preservation of cells and strong hybridisation signals is crucial. Tissue fixation and retention of cytoskeletal structures, unfortunately, impede diffusion of probes into tissues. ISH sensitivity is also influenced by inherent properties of the probe and hybridisation conditions. Although ISH is largely a research tool, it is already making strong inroads into diagnostic histopathology. It has been applied for the detection of various infective agents particularly CMV, HPV, HIV, JC virus, B19 parvovirus, HSV-1, EBV, HBV, hepatitis delta virus, Chlamydia trachomatis, salmonella and mycoplasma in tissue sections.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed2001

Absence of jaagsiekte sheep retrovirus DNA and RNA in bronchioloalveolar and conventional human pulmonary adenocarcinoma by PCR and RT-PCR analysis.

Bronchioloalveolar adenocarcinoma (BAC) morphologically resembles sheep pulmonary adenomatosis (SPA), a contagious ovine pulmonary adenocarcinoma caused by the jaagsiekte sheep retrovirus (JSRV). Previously, positivity for JSRV by immunostaining, reverse-transcription polymerase chain reaction (RT-PCR), and Western blot was reported in most nonmucinous BACs. Our objective in this study was to analyze additional BAC subtypes and conventional adenocarcinomas (CA) to further substantiate this association. Tumor tissue was microdissected from unstained paraffin sections of 26 cases of formalin-fixed, paraffin-embedded BAC (7 mucinous, 17 nonmucinous, 2 sclerosing) and 29 cases of CA. Positive controls consisted of 2 separate paraffin blocks of known SPA. Primer sequences were derived that were capable of hybridizing to all reported strain variants of both the DNA (endogenous) and RNA (exogenous) forms of JSRV. Each sample was tested using both PCR (DNA) and RT-PCR (RNA). All BAC and CA cases were negative for JSRV. Positive controls yielded PCR products that were sequenced and precisely matched the published prototype stain of JSRV. To control for negative effects of tissue fixation, dilutions of positive control tissue were added to BAC and CA samples. Detection of JSRV was evident at 1:50 dilution. Although the possibility of a viral association with BAC cannot be excluded, this study shows that the association with JSRV is probably very weak, if present at all.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed2005

Exposure of nuclear antigens in formalin-fixed, paraffin-embedded necropsy human spinal cord tissue: detection of NeuN.

Immunohistochemical and immunofluorescence staining approaches are powerful tools for characterization of the endogenous protein expression and subcellular compartmentalization. However, several technical problems hamper identification of low-abundance nuclear proteins in archival formalin-fixed, paraffin-embedded human neural tissue. These include loss of protein antigenicity during tissue fixation and processing, and intrinsic auto-fluorescence associated with the tissue related to its fixation and the presence of lipofuscin. We evaluated several antigen retrieval methods to establish a strategy for detection of neuronal nuclear proteins in human spinal cord formalin-fixed, paraffin-embedded tissue. Thus, using immunostaining of the neuron-specific nuclear protein NeuN as the outcome measure, we found that heating tissue sections in an alkaline pH buffer unmasked protein epitopes most effectively. Moreover, staining by immunohistochemistry with diaminobenzidine tetrahydrochloride chromagen was superior to immunofluorescence labeling, likely due to the signal amplification steps included in the former approach. Auto-fluorescence in the tissue sections can be effectively reduced, but a sufficient fluorescence signal associated with specific antibody labeling could not be detected above this background for NeuN in the nucleus.

Animals↗
PubMedDate not supplied

Cyclic pull-out strength of hamstring tendon graft fixation with soft tissue interference screws. Influence of screw length.

Blunt-threaded interference screws used for fixation of hamstring tendons in anterior cruciate ligament reconstructions provide aperture fixation and may provide a biomechanically more stable graft than a graft fixed further from the articular surface. It is unknown if soft tissue fixation strength using interference screws is affected by screw length. We compared the cyclic and time-zero pull-out forces of 7 x 25 mm and 7 x 40 mm blunt-threaded metal interference screws for hamstring graft tibial fixation in eight paired human cadaveric specimens. A four-stranded autologous hamstring tendon graft was secured by a blunt-threaded interference screw into a proximal tibial tunnel with a diameter corresponding to the graft width. Eight grafts were secured with a 25-mm length screw while the other eight paired grafts were secured with a 40-mm length screw. During cyclic testing, slippage of the graft occurred as the force of pull became greater with each cycle until the graft-screw complex ultimately failed. All grafts failed at the fixation site, with the tendon being pulled past the screw. There were no measurable differences in the mean cyclic failure strength, pull-out strength, or stiffness between the two sizes of screws. Although use of the longer screw would make removal technically easier should revision surgery be necessary, it did not provide stronger fixation strength than the shorter, standard screw as had been postulated.

Adult↗