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At least 721 records · Page 40Linked to original sources
PubMed1997

The effect of ofloxacin on the human corneal endothelium.

PURPOSE: Possible toxic effects of ofloxacin on human corneal endothelia were assessed by using electron microscopy and in vitro specular perfusion. METHODS: Five pairs of corneas [with one cornea of each pair receiving balanced salt solution (Endosol; Allergan, Irvine, CA, U.S.A.) and the other receiving Endosol with 10 micrograms/ml of ofloxacin] underwent perfusion for 3 h with corneal pachymetry every 15 min followed by tissue fixation. A mean corneal swelling rate was calculated from a first-order regression line fit for each of the five experiments. The swelling rates between groups was compared by-using a paired t test. Scanning and transmission electron micrographs were examined for cellular architecture. Another group of five pairs of corneas was perfused the same way with the only difference being a test dose of 30 micrograms/ml. RESULTS: The mean swelling rate for corneas perfused with 10 micrograms/ml of ofloxacin of -3.5 microns/h was not significantly different from that of the Endosol-alone corneas at -3.0 microns/h (p = 0.71). The mean swelling rate for corneas perfused at 30 micrograms/ml of ofloxacin was -4.1 microns/h, not significantly different from Endosol-alone perfused corneas at -6.5 microns/h (p = 0.08). No consistent ultrastructural changes could be attributed to exposure to 10 or 30 micrograms/ml of ofloxacin. CONCLUSION: Human corneal endothelium can be exposed to ofloxacin at a dose of 30 micrograms/ml for a period of 3 h without adverse ultrastructural or physiologic side effects.

Anti-Infective Agents↗
PubMed1996

[Simplified laparoscopic surgery in reflux disease by a modified polyglactin scarf].

The efficacy of an absorbable vicryl scarf has been developed by us for traditional reflux-disease management in cases of hiatus hernias. This vicryl scarf induces a subdiaphragmal connective-tissue fixation of the cardia, and, even after insertion of a prolene-net strip, it could be similarly successful in laparoscopy, increasing again the comfort for the patient.

Fundoplication↗
PubMed1996

Considerations in the application of selected molecular biology techniques in the clinical laboratory: preanalytical and analytical issues.

As a prerequisite to the utilization of molecular biology techniques in the clinical laboratory one must be aware of preanalytical pitfalls associated with these techniques. Procedures for the identification of restriction fragment length polymorphism (RFLP) resulting from variation in the number of tandem repeats (VNTR) of a short DNA segment, or even simple tandem repeats (STRs) such as dinucleotide repeats require scrutiny to understand both the strengths and limitations of these techniques. In terms of minimizing analytical pitfalls particular attention should be given to the composition of DNA probes. Many variables affect PCR (polymerase chain reaction). These include cycling temperatures chosen for denaturation of synthesized DNA strands, annealing and primer extension steps, the type of thermocyclers used to achieve temperature cycling, requirements for primers, to name just a few. Particular attention should be given for trouble shooting PCR products. A multiplicity of kits are currently available for the isolation of DNA and RNA. These kits while simplifying the isolation procedure could in some instances introduce a preanalytical variable depending on the type of detergent used in cell lysis which may impact on the amplification of DNA by techniques such as the polymerase chain reaction (PCR). The anticoagulants used for blood collection could also affect digestion with restriction enzymes and amplification reactions, such as been reported with heparin under certain conditions. Residual red blood cells can inhibit taq polymerase enzyme used in PCR amplification. The type of tissue fixative and the duration of fixation can affect the efficiency of amplification reactions. Finally, contamination from the working environment should be controlled to minimize both preanalytical and postanalytical error.

DNA↗
PubMed1997

Structural and ultrastructural study of the myocardium after 24-hour preservation in University of Wisconsin solution.

This study deals with myocardial preservation after 24 hours of continuous perfusion with University of Wisconsin (UW) solution, focusing on the morphological changes produced by preservation and reperfusion, and their possible relationship to the composition of the solution and the immediate hemodynamic findings after orthotopic heart transplantation in dogs. Following preservation, the histological images of the myocardium were normal in almost every case. After revascularization, although 50% of the hearts recovered preoperative functional levels, there were relevant histological changes in all of them. These changes consisted of interstitial edema, damage to at least 50% of the mitochondria, presence of contraction bands, loss of intercellular junction structure and vasoconstriction. According to these results, the association of continuous perfusion and UW solution appears to be effective during the ischemic period of prolonged myocardial preservation, but not during reperfusion. Perhaps the proportion of viable hearts could be increased by preventing vasoconstriction.

Animals↗
PubMed1976

Oxygen-induced enzyme release after irreversible myocardial injury. Effects of cyanide in perfused rat hearts.

The effects of 5 mM potassium cyanide (KCN) on creatine phosphokinase (CPK) release and cellular morphology were studied. Rat hearts were perfused with substrate-deficient media gassed with O2 or N2 (O2 medium, N2 medium) at 37 C, and effluent was collected for creatine phosphokinase analysis. Tissue fixation was with glutaraldehyde for light and electron microscopy. Experiments included the following: a) continuous perfusion with O2- or N2-medium in the presence of KCN; b) 45 or 60 minutes of perfusion with N2-medium followed by O2-medium for 15 or 180 minutes, respectively; c) 45 minutes of perfusion with N2-medium with KCN added 15 minutes before reoxygenation with O2-medium plus KCN; (4) 60 minutes of N2-medium plus KCN followed by O2-medium plus KCN for 180 minutes; d) as a control for irreversible injury, 21 minutes of perfusion with calcium-free O2-medium followed by 2.5 mM calcium-O2-medium ("calcium paradox"). The following results were seen: a) Initial CPK release occurred about 30 minutes later from hearts perfused with O2-medium plus KCN than from hearts perfused with N2-medium plus KCN. b) Upon reoxygenation after either 45 or 60 minutes of anoxia, hearts had a sudden peak of oxygen-induced CPK release. Most irreversibly injured cells were massively swollen and had sarcolemmal defects and contraction bands. Reversibly injured cells in the same hearts resembled normal myocardium. A previously unrecognized third population of cells is described. These cells were characterized by contraction bands but were not swollen, had intact sarcolemma, and contained both normal and damaged mitochondria with intramatrical calcium accumulation granules. It could not be determined if these cells were reversibly injured or in an early stage of irreversible injury. c) KCN added 15 minutes before reoxygenation of hearts after 45 minutes of anoxia inhibited the sudden peak of oxygen-induced CPK release but not a slow sustained release. Small to moderate numbers of cells in these hearts contained contraction bands. d) After 60 minutes, KCN completely inhibited both oxygen-induced CPK release and contraction band formation. e) Addition of calcium to calcium-free hearts caused both massive CPK release and contraction band formation. It is concluded that: the beginning of CPK release from oxygenated KCN-inhibited hearts requires about 30 minutes longer than from anoxic hearts; KCN can inhibit both oxygen-induced CPK release and contraction bands in irreversibly injured rat myocardial cells; sudden contracture of myocardial cells as occurs in the calcium paradox can result in massive CPK release; contraction bands occur in nonswollen cells, hence contraction bands can occur independently of massive cell swelling or membrane rupture. It is postulated that there may be two stages of irreversible myocardial injury; a) loss of control of contraction and b) progressive loss of mitochondrial and membrane integrity.

Animals↗
PubMedDate not supplied

[Expression of cathepsin D in breast cancer and its clinical and histopathological correlations].

BACKGROUND: Cathepsin D is a lysosomal protease which is overexpressed in some cases of breast cancer. Several studies done in tumor cytosol have shown that high levels of cathepsin D are associated with poor prognosis in patients with breast cancer but the results are not conclusive using immunohistochemistry methods to assay cathepsin D. OBJECTIVE: To evaluate if cathepsin D, assayed by a immunohistochemical technique using a polyclonal antibody, can be considered an independent prognostic factor in breast cancer. PATIENTS AND METHODS: Paraffine embedded sections of 68 tumor specimens from breast cancer patients in stages I to IV seen at the Instituto Nacional de Cancerologia during the period from 1985 to 1986. RESULTS: From the 68 patients, 35 (51%) had an intense positive staining for cathepsin D, 19 (28%) han mild staining and 14 (21%) were negative. Ten patients with mild staining had artifacts due to deficiencies in the tissue fixation technique. Cathepsin D expression did not have a prognostic value nor association with other clinical and histopathological prognostic factors well established in breast cancer. CONCLUSION: Cathepsin D determined by immunohistochemistry has no prognostic value in breast cancer.

Adult↗
PubMed1996

In situ hybridization, in situ transcription, and in situ polymerase chain reaction.

In situ hybridization, in situ transcription, and in situ polymerase chain reaction (PCR) are techniques used to detect DNA and RNA sequences within a cell or tissue structure. These three in situ methodologies employ the principles of recombinant DNA to form double-stranded hybrids of DNA-DNA, DNA-RNA, or RNA-RNA. The essence of in situ hybridization (ISH) is the hybridization of a labeled probe to a complementary target sequence, whereas in situ transcription (IST) is the synthesis of complementary DNA incorporating a label directly on the target DNA or RNA within a cell or tissue. In the case of in situ PCR (ISPCR), it is the repeated in situ duplication of both the sense and antisense strands of DNA to increase the number of copies of the target sequence. ISH, IST, and ISPCR each have their advantages and disadvantages. The purpose of this chapter is to address in situ considerations required of these techniques, emphasizing tissue fixation, pre-hybridization steps, DNA probes, RNA probes, oligoprobes, and probe labeling. Five successfully used protocols are presented as examples. Any given nucleotide target sequence may have its own unique set of optimum conditions, thus requiring some adjustment in the hands of the user.

DNA↗
PubMed1976

Permanent pervenous atrial pacing.

A new J-lead has now been designed and manufactured for both animal and clinical studies. This lead has silastic tines proximal to the electrode, arranged so that they become entangled in the trabeculae of the appendage and hold the lead in place. Studies in ten dogs have shown excellent tissue fixation at the site of the tines, and only minimal scarring occurs at the site of the terminal electrode, with preservation of good P-wave amplitude and good stimulating thresholds for a period of four to five months (Figure 8, see next page). The lead designed for humans has been used successfully in 12 patients. Follow-up now extends to 19 months, with stable P-wave-triggered atrial pacing in eight patients, fixed rate atrial pacing in one, and A-V synchronized pacing in three. No lead dislodgement has occurred.

Catheterization↗
PubMed1998

The sinus endothelial cell architecture in the mouse lymph node. Structural peculiarities and close correlation with the fibroblastic reticular cells.

The sinus endothelial cell architecture has been studied in the mouse lymph node by light and electron microscopy after tissue fixation with an osmium-zinc iodide mixture. This histochemical method allowed visualization of sinus endothelial cells in the medullary and, partly, in the intermediate sinuses. The osmium-zinc iodide reaction also demonstrated fibroblastic reticular cells, which represent the main stromal cell population in the lymph node and form the skeletal framework of the organ as well as the adventitia of sinuses. In the mouse lymph nodes, sinuses were lined by a simple layer of sinus endothelial cells whose integrity and continuity showed interruptions of various extension. In areas devoid of complete sinus endothelial cell lining, fibroblastic reticular cells located in the nearby parenchyma were able to reach the border of the sinus, being thus in direct contact with the lumen content. Dendritic sinus endothelial cells as well as intermediate forms between sinus endothelial cells and fibroblastic reticular cells could be observed. The close structural characteristics that sinus endothelial cells have in common with fibroblastic reticular cells and the finding of transitional cells with intermediate morphology between sinus endothelial cells and fibroblastic reticular cells, suggest a possible origin of sinus endothelial cells by migration and differentiation of fibroblastic reticular cells located in the sinus adventitia.

Animals↗
PubMed1987

Fixation of neural tissue for electron microscopy with an electronically controlled perfusion pump.

Many attempts to improve the perfusion of mammalian tissues aim at changes of the osmotic pressure. We describe a method for fixation of nervous tissues controlling both the hydrostatic pressure and the flow rate of a perfusion solution. The constancy of these parameters is guaranteed by an electronically controlled perfusion pump. Thus, a more uniform and complete preservation can be achieved. Further advantages of this method include provision for a rapid succession of rinsing and fixation solution and a continuous control of the hydrostatic pressure during perfusion.

Animals↗
PubMed1978

Fixatives and methods of fixation in selected tissues of the laboratory rat.

The histologic appearances of tissues fixed by immersion and perfusion were compared, as well as the effects of these different fixatives: 10% neutral buffered formalin, Carnoy's fluid, and Bouin's fluid. Intravascular perfusion provided better tissue preservation than fixation by immersion. The quality of preservation by neutral buffered formalin was equal to that of Carnoy's fluid and Bouin's fluid, but the overall staining quality of the latter two was judged to be superior.

Animals↗
PubMed1988

c-myc protein in normal tissue. Effects of fixation on its apparent subcellular distribution.

The c-myc protein is thought to be a DNA-associated nuclear protein. However, immunohistochemical studies on normal or tumor tissues have shown conflicting findings on its subcellular distribution. By using various fixation procedures on cytospin preparations of HL60 cells, the authors found the subcellular distribution of the c-myc protein to be dependent on the method of fixation. When studying mouse tissues in frozen sections using a biotinylated monoclonal antibody against the c-myc protein, they found the protein to be widely distributed in various normal adult mouse tissues, in most cases localized to the nucleus. However, when these tissues were studied after formalin fixation and paraffin embedding, a loss of nuclear staining was observed concurrent with the appearance of c-myc protein immunoreactivity in the cytoplasm. It is concluded that immunohistochemical studies on the expression of this oncogene should take into consideration the effects of fixation when its subcellular distribution is being examined.

Animals↗
PubMed2000

Ultrastructural preservation of rat embryonic dental tissues after rapid fixation and dehydration under microwave irradiation.

Adequate preservation of the cells and matrix of mineralising tissues remains difficult, as organic components and initial mineral deposits may be lost during conventional processing for electron microscopy. In this study, we have reduced significantly the processing time using microwave irradiation. Rat molar tooth germs were fixed in 4% glutaraldehyde + 4% formaldehyde with 0.1 M sodium cacodylate in a laboratory microwave oven for two periods of 20 s with a maximal temperature of 37 degrees C. After conventional washing and post-fixation, specimens were dehydrated in graded ethanols under microwave irradiation for a total of 7 min 20 s. For comparison, some specimens were processed by conventional methods. After embedding, ultrathin sections were examined by electron microscopy. In differentiating ameloblasts and odontoblasts, plasma membranes, mitochondria, rough endoplasmic reticulum, the Golgi complex, together with all other cytoplasmic organelles exhibited excellent preservation. Microtubules, microfilaments and coated vesicles were particularly evident. Crystal-like mineral deposits were conspicuously present in relation to dentine matrix vesicles and collagen fibrils as well as in enamel matrix. The matrix of forming enamel had a globular electron-lucent appearance. It is concluded that this is a rapid method which provides a preserved or even improved morphology.

Ameloblasts↗
PubMed1993

Morphological aspects of chromaffin tissue: the differential fixation of adrenaline and noradrenaline.

The morphological aspects of chromaffin tissue are reviewed, based mainly on our studies on the mouse adrenal gland. Particular attention was focused on the differential fixation of adrenaline and noradrenaline, and on the uptake and storage of [3H]dopa, [3H]dopamine and related substances in the adrenaline-storing (A) and noradrenaline-storing (NA) cells. Scanning electron microscopy combined with the NaOH-maceration method was useful for demonstrating the 3-dimensional organisation of nerve terminals, chromaffin cells, glial elements and vascular elements. In transmission electron microscopy, 3 types of chromaffin cell were distinguished. They were A, NA and SGC (small granule chromaffin) cells. After glutaraldehyde fixation followed by postosmication, A cell granules showed lower electron density, whereas NA cell granules were solid and dark. This difference in appearance between A and NA cells was first explained by the hypothesis that, after glutaraldehyde fixation, most of the adrenaline dissolved, whereas noradrenaline was precipitated in situ. Later, this hypothesis was supported by a series of autoradiographic and radioisotopic assay studies using [3H]dopa, [3H]dopamine and related substances; when [3H]adrenaline occurred, radioactivity in A cells mostly disappeared in the specimen, whereas that in the NA cells remained. At 15-60 min after an i.p. injection of [3H]dopa or [3H]dopamine, the concentration of radioactivity in A cells was higher than that in NA cells. However, in hypophysectomised mice, the radioactivity was low and evenly distributed in these 2 types of chromaffin cell. It was deduced that the carrier activities for extracellular dopa and dopamine were made greater in the A cells than in the NA cells by the pituitary gland. The hypophysectomy effects were restored by i.p. administration of ACTH.

Adrenal Medulla↗
PubMed1975

[Local traumatic injury of the soft tissue and internal fixation (author's transl)].

The influence of local traumatic injury of the soft tissue on the decision as to whether surgical therapy is indicated and on the method of internal fixation selected for a fresh, closed fracture is discussed. General descriptions of injuries to the soft tissue are followed by a critical discussion of the possibilities of closed and open methods of internal fixation with some examples.

Fracture Fixation↗
PubMed2004

[Soft tissue tendon graft fixation in the tibial tunnel with a bioabsorbable screw-EndoPearl combination in tibiae of low bone mineral density: a biomechanical study].

OBJECTIVES: This biomechanical study evaluated soft tissue tendon graft fixation in the tibial tunnel using a bioabsorbable interference screw with or without supplemental EndoPearl device. METHODS: Ten bovine tibiae were stripped of all soft tissues and bone tunnels 7 mm in diameter were drilled with dilation to 9 mm. Tibialis anterior allografts were fixed with a screw (10 mm in diameter, 30 mm in length) in five tibiae of high bone mineral density (1.36 g/cm2), and with a screw-EndoPearl combination in five tibiae of low bone mineral density (0.84 g/cm2). The specimens were cycled 10 times from 10 to 50 N, and 500 times from 50 to 200 N in a servo hydraulic test device prior to ultimate load-at-failure testing at a rate of 20 mm/min. RESULTS: No statistically significant differences were found between the two fixation groups with respect to displacement and stiffness during cyclic testing, and with respect to load at failure, displacement, and stiffness during load-to-failure testing (p>0.05). CONCLUSION: The finding of similar results in both fixation groups with respect to displacement and stiffness during cyclic testing and during load-to-failure testing suggests that a screw-EndoPearl combination in tibiae of low bone mineral density may be helpful in the prevention of graft slippage.

Absorbable Implants↗
PubMed1999

Biocompatibility of a novel tissue connector for fixation of tracheostoma valves and shunt valves.

Rehabilitation after laryngectomy often includes the use of a shunt valve and a tracheostoma valve to restore voice. To improve the fixation method of these valves, a new tissue connector has been developed, basically consisting of a ring that will be integrated into surrounding tracheal soft tissue. The valves can be placed in the ring. To test the principle of the tissue connector, a prototype consisting of a subcutaneous polypropylene mesh and a percutaneous titanium stylus was implanted into the backskin of 10 rats by a two-stage surgical procedure. We reasoned that if a firm connection can be realized with the skin, a firm connection with the trachea will also be possible. The subcutaneous part was implanted first, followed by the percutaneous part after 6 weeks. The complete tissue connector with surrounding tissue was removed 8 weeks later and examined histologically. The principle of the new tissue connector proved to be effective: hardly any epithelial downgrowth appeared, and adhesion of soft tissue was demonstrated. No infection or severe inflammation reaction was detected. The tissue connector seems appropriate for its intended use.

Administration, Cutaneous↗