Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.24.3 (collagenase)
18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Rat hepatocytes were isolated by liver perfusion in the presence of collagenase and hyaluronidase and incubated in the absence or presence of oxygen. As a result of anoxia, there was a gradual increase in plasma membrane permeability, noted as an increase in succinate-stimulated oxygen uptake, a decrease in trypan blue exclusion frequency, a leakage of cytosolic lactate dehydrogenase activity and an increased proportion of swollen and disrupted cells. After anaerobic incubation for 30 minutes--but not for 60 minutes--there were signs of recovery from anoxic cell injury upon re-oxygenation. The changes in plasma membrane permeability properties in anoxia seemed to be preceded by a marked decrease in cellular ATP level; aerobic incubation of hepatocytes in the presence of an uncoupler of phosphorylation from respiration led to a similar decrease in cellular ATP concentration followed by similar disturbances in plasma membrane permeability properties. It is suggested that a distrubed plasma membrane function caused by a decreased energy level is of primary importance for the initiation of cell death in anoxia.
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PMID:Isolated rat hepatocytes as an experimental tool in the study of cell injury. Effect of anoxia. 100 75

Cross-linked collagen bioprostheses usually are designed to be inert and nonresorbable, resulting in fatigue and wear failure in high-stress environments. Eventual replacement of the implant, although minimizing strength loss during resorption, would result in a graft with reparative ability. Kangaroo tail tendon (KTT) partially cross-linked with glutaraldehyde (GA) was evaluated in vitro for resistance to bacterial collagenase digestion and in vivo for biocompatibility and resorbability in an intramuscular implant assay. Cross-linking was quantified by thermal denaturation studies. Incomplete cross-linking was achieved with concentrations of GA less than 0.1% (w/v). KTT cross-linked in greater than or equal to 0.05% GA were collagenase resistant being incompletely digested after 240 h. Cross-linking of KTT with low concentrations of GA resulted in partial collagenase resistance and slowed resorption.
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PMID:Collagen cross-linking and resorption: effect of glutaraldehyde concentration. 212 27

Transcription and translation activity in relation to oxygen consumption have been measured in isolated liver cells from freely fed tumor-bearing mice and compared with that of freely fed controls. The liver cells were isolated by perfusion of livers in situ with a collagenase containing buffer. Adult nongrowing mice with a methylcholanthrene induced sarcoma were used. Liver cells under the remote effect of the malignant tumor had increased transcription and translation of hepatic proteins in spite of decreased cellular oxygen consumption. The mechanisms behind increased hepatic protein synthesis concomitant with decreased energy production in the tumor-influenced liver are unknown, but we suggest that the hepatic translation of some genetic information may be of importance for the host survival in the tumor-bearing condition.
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PMID:Transcriptional and translational activity in relation to oxygen consumption in isolated liver cells from sarcoma-bearing mice. 619 66

Rat cardiac myocytes were isolated by heart perfusion in the presence of collagenase and incubated in the absence of presence of oxygen. As a result of anoxia, there was a gradual increase in plasma membrane permeability, noted as a decrease in trypan blue exclusion frequency, leakage of cytosolic lactate dehydrogenase and intracellular accumulation of the isotope compound 99Tcm-gluconate. The changes in plasma membrane permeability properties were preceded by a marked decrease in cellular ATP level and an increased proportion of contracted myocytes. The ability of the myocytes to resynthesize ATP and to recover from the anoxic injury upon reoxygenation decreased gradually with the length of initial anaerobic incubation during the first 25 min and disappeared after 30 min of anoxia, indicating that the anoxic injury to the isolated rat cardiac myocytes becomes irreversible after 25--30 min of anoxia. It is suggested that a decreased energy level is of primary importance for the initiation of cell injury in anoxia and that it is followed by cell contracture and subsequently by a disturbed plasma membrane function, cell swelling and death. This experimental model system of isolated viable rat cardiac myocytes is suitable for problems dealing with reversibility of myocytic injury.
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PMID:Isolated rat cardiac myocytes as an experimental tool in the study of anoxic cell injury. Effect of reoxygenation--a preliminary report. 720 17

The uptake and accumulation of 1-5 microM cadmium (Cd) was studied in primary cultures of rat renal cortical epithelial cells under protein-free conditions at 4 or 37 degrees C for up to 30 min. The cells were isolated from female rats by collagenase digestion and cultured for 3-7 days. Confluency of the culture, monitored morphologically as well as by total protein content, was achieved on Day 5. Cd accumulation at 1 microM concentration demonstrated an inverse relationship to the cell density; the Cd level in Day 5 culture was only 45% of that in Day 3 culture. In subconfluent cultures (Days 3 and 4) the Cd accumulation was temperature sensitive; on Day 3 the cells accumulated one-third less Cd at 4 degrees C than at 37 degrees C. In comparison, the confluent cells (Day 5) had the same Cd accumulation regardless of the incubation temperature. In these cells, preincubation with cyanide also had no significant effect on Cd accumulation, implying a lack of energy requirement for Cd uptake. As the transport of Cd may involve processes that exist for the essential metal ions, the effect of 30 microM zinc (Zn) and copper (Cu) on the accumulation of 1 microM Cd was studied in Day 5 cultures. Coincubation with Zn caused a 16% reduction in Cd levels at 37 degrees C and even greater reduction (44% of control) at 4 degrees C. Similarly, Cu inhibited Cd accumulation by 26 and 45% at 37 and 4 degrees C, respectively, as compared to the temperature-matched controls. The Vmax for the initial Cd uptake (1 min) was 125 pmol/mg protein/min and the Km was 7 microM. Both Zn and Cu exhibited competitive inhibition kinetics and doubled the Km for Cd uptake. The Ki for Zn and Cu was 23 and 30 microM, respectively. Mercury (Hg) and lead (Pb) were also tested for their ability to affect Cd accumulation. As compared to the controls, 1 microM Hg caused an 11% reduction in Cd level at 37 degrees C. In contrast, 1 microM Pb enhanced Cd accumulation by 20%. However, neither Hg nor Pb had any significant effect on Cd accumulation at 4 degrees C. All four metals had no significant effect on the efflux of Cd from the cells. Thus, these metals affected Cd accumulation by changing its uptake rather than its efflux.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Cadmium uptake by primary cultures of rat renal cortical epithelial cells: influence of cell density and other metal ions. 834 37

Bioprosthetic heart valves fail as the result of two simultaneous processes: structural deterioration and calcification. Leaflet deterioration and perforation have been correlated with regions of highest stress in the tissue. The failures have long been assumed to be due to simple mechanical fatigue of the collagen fibre architecture; however, we have hypothesized that local stresses-and particularly dynamic stresses-accelerate local proteolysis, leading to tissue failure. This study addresses that hypothesis. Using a novel, custom-built microtensile culture system, strips of bovine pericardium were subjected to static and dynamic loads while being exposed to solutions of microbial collagenase or trypsin (a non-specific proteolytic enzyme). The time to extend to 30% strain (defined here as time to failure) was recorded. After failure, the percentage of collagen solubilized was calculated based on the amount of hydroxyproline present in solution. All data were analyzed by analysis of variance (ANOVA). In collagenase, exposure to static load significantly decreased the time to failure (P < 0.002) due to increased mean rate of collagen solubilization. Importantly, specimens exposed to collagenase and dynamic load failed faster than those exposed to collagenase under the same average static load (P = 0.02). In trypsin, by contrast, static load never led to failure and produced only minimal degradation. Under dynamic load, however, specimens exposed to collagenase, trypsin, and even Tris/CaCl2 buffer solution, all failed. Only samples exposed to Hanks' physiological solution did not fail. Failure of the specimens exposed to trypsin and Tris/CaCl2 suggests that the non-collagenous components and the calcium-dependent proteolytic enzymes present in pericardial tissue may play roles in the pathogenesis of bioprosthetic heart valve degeneration.
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PMID:Mechanical loading of bovine pericardium accelerates enzymatic degradation. 1038 30

Mechanical loading contributes to the structural deterioration of bioprosthetic heart valves. The influence of stress state during fixation may play a substantial role in their failure, linking fatigue damage caused by buckling and tension and the enzymatic degradation of glutaraldehyde-crosslinked collagen. Bovine pericardia were obtained immediately postmortem and 100 mm x 15 mm samples were cut in the base-to-apex direction. Half the samples were subjected to a uniaxial tensile stress of 250 kPa and half remained unloaded during a crosslinking treatment in 0.5% glutaraldehyde. Tissue samples were rinsed and cut into 16 mm x 4 mm test strips. Half of these strips were exposed to cyclic compressive buckling and alternating tension at 30 Hz for 20 million cycles (approx. 7.5 days) using a custom-built multi-sample fatigue system. Fatigue-damaged and non-damaged samples were subsequently incubated at 37 C for 48 hrs in: (i) Type I bacterial collagenase (20 U/ml) buffered in 0.05 M Tris, 10 mM CaCl2 2H2O (pH 7.4) or (ii) 0.05 M Tris buffer (pH 7.4) only. In both cases, the samples were loaded sinusoidally between 40 and 80 g using a previously described microtensile culture system. Tissue removed from the bath was rinsed in 0.1 M EDTA solution and mounted in a servo-hydraulic mechanical testing system (MTS). Ultimate tensile strength (UTS), maximum tissue modulus, and fracture strain were determined. The percent collagen solubilized was assessed by a colourmetric hydroxyproline assay of the enzyme bath and tissue sample. All data were analyzed by analysis of variance (ANOVA). The results confirmed the synergy between fatigue damage and collagenase proteolysis in these materials; however, there were no significant differences in this effect between simple fixation and stress-fixation up to 20 million cycles. There were significant decreases in the mechanical properties and an increase in the amount of collagen solubilized with increased exposure to fatigue cycling.
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PMID:Stress state during fixation determines susceptibility to fatigue-linked biodegradation in bioprosthetic heart valve materials. 1208 92

Tendon overuse injuries are a major source of clinical concern. Cyclic loading causes material damage and induces biochemical responses in tendon. The purpose of this study was to examine the biochemical and biomechanical tendon response after applying cyclical loading over varying durations. Avian flexor digitorum profundus tendons were loaded (3 or 12 MPa) to a fixed number of cycles across either 1 or 12 days in vitro. The tendon response evaluations included biomechanical data gathered during loading and subsequent failure testing. Evaluations also included cellular viability, cell death, and proteoglycan, collagen, collagenase, and prostaglandin E(2) (PGE(2)) content measurements obtained from tissue specimens and media samples. Significant strains (up to 2%) accumulated during loading. Loading to 12 MPa significantly reduced maximum stress (33% and 27%) and energy density (42% and 50%) when applied across 1 or 12 days, respectively. Loading to 3 MPa also caused a 40% reduction in energy density, but only when applied across 12 days. Cell death and collagenase activity increased significantly with increasing magnitude and duration. However, no differences occurred in cell viability or collagen content. Glycosaminoglycan content increased 50% with load magnitude, while PGE(2) production increased 2.5-fold with loading magnitude and 11-fold with increased duration. Mechanical fatigue-induced mechanical property changes were exhibited by the tendons in response to increased loading magnitude across just 1 day. However, when the same loading was applied over a longer period, most outcomes were magnified substantially, relative to the short duration regimens. This is presumably due to the increased response time for the complex cellular response to loading. A key contributor may be the inflammatory mediator, PGE(2), which exhibited large magnitude and duration dependent increases to cyclic loading.
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PMID:Distributing a fixed amount of cyclic loading to tendon explants over longer periods induces greater cellular and mechanical responses. 1745 18

This study explored the hypothesis that local administration of a polysulphated glycosaminoglycan (PSGAG) in the early phase of healing of a standard collagenase-induced tendon injury in the superficial digital flexor tendon of the rabbit would reduce the degenerative effects of inflammatory mediators and proteases and preserve normal tendon morphology, composition, and biomechanical properties. Histological and ultrastructural changes together with the mechanical properties, dry weight, collagen content, and amount of DNA in healing tissue at the site of the lesion were assessed in treated and untreated animals. In treated lesions 28 days after injury, the normal orientation of tenoblasts and collagen fibrils was well preserved compared with the disorganized scar formation seen in untreated animals. The degree of cellularity was significantly higher in the untreated lesions. At the ultrastructural level the collagen in the healing tissue of the treated animals consisted of a mixture of small diameter, new regenerated fibrils intermingled with well-preserved large diameter, old fibrils, aligned to the long axis of the tendon; in untreated animals small, randomly arranged new fibrils predominated. The diameters of treated tendons had returned to normal, but in untreated animals the injured tendons remained significantly thicker than their controls. The percentage dry weight and collagen contents of treated injured tendons approximated those of control normal tendons, whereas those of untreated tendons were significantly less than those of the control values. The DNA content of injured treated tendons was not significantly different from that of normal contralateral controls, while in the untreated tendons it was significantly higher. There were no significant differences between the normal and the contralateral treated injured tendons in ultimate strength, fatigue strength, stiffness, and maximum absorbed energy. However in the untreated animals, although the tendon diameter was significantly greater, the ultimate strength, fatigue strength, stiffness, and maximum absorbed energy were significantly lower than the contralateral control. These data suggest that polysulphated glycosaminoglycans are effective in restoring the morphological, biochemical, and biomechanical properties of injured soft connective tissues and may be of clinical value in the treatment of acute tendon injury.
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PMID:Response of a collagenase-induced tendon injury to treatment with a polysulphated glycosaminoglycan (Adequan). 1899 Oct 88

Glutaraldehyde (GLUT) crosslinked porcine aortic heart valves are continued to be extensively used in heart valve replacement surgeries. GLUT does not crosslink glycosaminoglycans in the tissue and we have demonstrated that GAG loss is associated with tissue degeneration. In this study, we examined the ability of neomycin to enhance GLUT crosslinking to stabilize GAGs, as well as provide evidence of improved functional integrity. Neomycin enhanced GLUT crosslinked (NG) leaflets exposed to collagenase and elastase enzymes exhibited an increased resistance to proteolytic degradation. Furthermore, NG leaflets exhibited small but significant increases in collagen denaturation temperatures when compared to that of standard GLUT crosslinked BHVs. NG leaflets subjected to storage, accelerated cyclic fatigue, and in vitro enzyme mediated GAG degradation revealed improved GAG stabilization versus standard GLUT crosslinked valves, which sustained substantial decreases in GAG content. Ultrastructural analysis using transmission electron microscopy qualitatively confirmed NG leaflets preserved GAGs after enzymatic degradation. Biomechanical analyses demonstrated that NG leaflets were functionally similar to GLUT tissues but were slightly stiffer under both planar biaxial tension and under flexure. Interestingly, after GAGase treatment, GLUT tissues showed increased areal compliance and reduced hysteresis, while NG leaflets were unchanged. Collectively, NG cross-linking functionally insulated the tissue from GAG digestion, and imparted modest additional matrix stiffness but maintained tissue hysteresis properties.
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PMID:Neomycin enhances extracellular matrix stability of glutaraldehyde crosslinked bioprosthetic heart valves. 2171 85


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