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At least 55 records · Page 3Linked to original sources
PubMed1979

Effect of mast cell chymase of rat skin on intercellular matrix: a histochemical study.

The effects of purified mast cell chymase of rat skin on intercellular matrix were studied histochemically using cartilage as a model. The enzyme effectively releases proteoglycans from neonatal human costal cartilage. An analysis of the primary site of proteolytic attack by chymase in the matrix was attempted. The results suggest that components containing the more acidic radicals (e.g. sulphates) are hydrolyzed first. After a prolonged attack, the matrix loses most of its staining with Toluidine Blue and Alcian Blue, and staining of collagen is increased. The hydrolyzed regions of cartilage in Alcian Blue-stained sections exhibited a purple interference colour in polarized light. A similar interference colour appeared after incubating sections of rat skin with chymase. The mast cell chymase presumably promotes diffusion of plasma to the site of injury by the direct breakdown of connective tissue ground substance.

Animals↗
PubMedDate not supplied

[Trypsin immobilization on a mineral matrix].

Trypsin immobilization on the mineral matrix--silochrome was studied. The effect of the matrix electrochemical nature on the process was examined. pH-optima for trypsin binding with different silochromes and pH-optimum of action of the immobilized enzyme on casein were determined. The effect on the trypsin-silochrome binding of different supplements--inhibitors (benzamidine), stabilizers (Ca2+) and substrates (casein, benzoyl argininamide hydrochloride) was demonstrated.

Caseins↗
PubMed1979

[The use of organic bone matrix as material for direct pulp capping].

The effect of bone matrix soaked in thyrocalcitonin on vitally amputated pulp was studied in beagle dogs with light and electron microscopy. All treated teeth were vital after eight weeks; the area of implantation was densely populated with cells. Formation of hard tissue differing from normal dentinogenesis had begun.

Animals↗
PubMed2025

UV-based homogeneous disinfection process for removal of antibiotic resistance genes: Efficiency, mechanisms and influencing factors.

The proliferation and dissemination of antibiotic resistance genes (ARGs) in aquatic environments pose a serious threat to global public health. Ultraviolet-driven homogeneous advanced oxidation processes (UV-AOPs) represent a prospective suite of technologies for the efficient removal of ARGs. This review critically assesses recent advances in the application of UV-AOPs, specifically UV/hydrogen peroxide (UV/H2O2), UV/peracetic acid (UV/PAA), UV/persulfate (UV/PS), and UV/chlorine (UV/Cl), for the elimination of extracellular ARGs and intracellular ARGs. The underlying mechanisms involve direct ultraviolet-induced DNA damage, including pyrimidine dimer formation and strand breakage, as well as oxidation mediated by radicals such as hydroxyl radicals, sulfate radicals, carbon-centered radicals, and reactive chlorine species. The relative contribution of radical and non-radical pathways is strongly influenced by water chemistry and process conditions. We further expound on the critical operational and environmental factors governing ARG removal kinetics, including UV wavelength and fluence, oxidant type and dosage, ARG sequence characteristics, pH, ubiquitous anions, and dissolved organic matter, which collectively affect radical generation, quenching, and reaction microenvironments. Notably, for i-ARGs, UV-AOPs facilitate degradation not only through direct radical attack but also by disrupting cellular integrity and permeabilizing membranes, thereby enhancing the exposure of genetic materials to oxidative and photolytic damage. This review synthesizes current understanding to provide a mechanistic basis for the design and optimization of UV-AOP systems, highlighting their potential as effective barriers against the dissemination of antibiotic resistance in water reuse and purification scenarios.

Disinfection↗
PubMed1975

Affinity chromatography of viral DNA polymerases on pyran-sepharose.

Pyran covalently linked to cyanogen bromide-activated Sepharose has been shown to be an effective affinity matrix for several viral DNA polymerases. Differential salt elution of viral compared with cellular polymerases, as well as substrate elution, suggests the affinity nature for the matrix. Unlike some other affinity systems described, pyran-Sepharose is totally resistant to nuclease digestion and is stable at 4 degrees for several months. DNA polymerases isolated from several viruses by detergent treatment were recovered in good yield. Analysis of iodinated proteins by sodium dodecyl sulfate-gel electrophoresis revealed that the DNA polymerase of avian myeloblastosis virus found in crude preparations of the virus could be purified nearly to homogeneity by a single passage through the column. These results suggest that pyran-Sepharose is an effective affinity column that is potentially adaptable as part of a general purification procedure for viral DNA polymerases.

Animals↗
PubMed1978

The effect of ethane-1-hydroxy-1, 1-diphosphonic acid (EHDP) on matrix induced ectopic bone formation.

The effect of diphosphonates (EHDP) was studied on induced ectopic osteoneogenesis. Decalcified allogeneic bone matrix was implanted into the lumbar muscles in rabbits for an ectopic osteoinductor. The ectopic new bone formation was studied under continuous EHDP administration and after discontinuation of EHDP. Although there was no inhibitory effect of EHDP on the osteoinduction, the calcification of the new bone and the resorption of the implanted matrix was retarded. The induced "osteoid-like" tissue had an atypical structure with a small number of cells and a deficiency in collagen fiber bundles. There were also large fields of new cartilage formation. Thus remodelling and mineralization were inhibited under the influence of continuous administration of EHDP. After discontinuation of EHDP administration a recovery phase was observed which seemed to lead to the formation of a normal ossicle.

Animals↗
PubMed1979

Effect of hyperoxia on articular tissues in organ culture.

The effect of hyperoxia on pig articular tissue has been studied in organ culture. Hyperoxia (55% O2) causes an increased release of hydroxyproline and collagenolytic activity from synovial tissue as compared with control explants in 20% O2, but neither 55% nor 95% O2 has any effect on the breakdown of isolated cartilage during 10 days in culture. When synovium and cartilage are cultured in contact, the breakdown of cartilage collagen is greater in the hyperoxic (55% O2) group than in the controls (20% O2), but the breakdown of proteoglycan is not increased. The enhanced collagenolytic action is due to an increase in the direct effect of the synovial tissue on the cartilage matrix. In 20% O2 the synovium causes the chondrocytes to degrade the cartilage matrix, but this effect is inhibited by 55% O2.

Animals↗
PubMed1977

Spectral characteristics of metachromatically stained cartilage: effects of enzymatic degradation and dehydration.

When a microspectrophotometer was used to study cartilage, stained metachromatically with Azure A and Safranin O, the following 3 points were made: 1. the absorption maximum of stained cartilage matrix is identical to that reported for solutions of these dyes containing chondroitin sulfate; 2. partial enzymatic degradation of the cartilage matrix has no effect on the position of the absorption peak (although the intensity is greatly diminished); 3. ethanolic dehydration shifts the absorption peak somewhat toward the orthochromatic position, and decreases the intensity of the stain.

Cartilage↗
PubMed1975

Affinity chromatography on immobilised nucleotides. Some applications to the purification of thermophilic dehydrogenases and kinases.

The effect of pH and temperature on the capacity and binding of Bacillus stearothermophilus, alcohol dehydrogenase and phosphofructokinase to N6-(6-aminohexyl)-5'-AMP-Sepharose has been examined. Specific elution from the substituted AMP-Sepharose was examined using a variety of cofactors, fragments of cofactors and substrates. A purification scheme for each enzyme on the substituted AMP-Sepharose using nucleotides and gradients of pH and salt is presented. Interestingly, elevated temperature increased the affinity of both enzymes for N6-(6-aminohexyl)-5'-AMP-Sepharose, however, the Michaelis constant for nucleotide determined at various temperatures remained constant. The effect of pH and salt concentration on the binding of B. stearothermophilus glyceraldehyde-3-phosphate dehydrogenase to 6-aminohexanoyl-NAD+-Sepharose was also examined; raising the pH above 7.5 lowers the capacity of the matrix and the effect of a range of ammonium sulphate concentrations on the adsorption of the enzyme was examined. A specific purification of glyceraldehyde-3-phosphate dehydrogenase from partially purified extracts of this organism was achieved.

Adenosine Monophosphate↗
PubMed1978

Reverse transcriptase: a monitor for perturbation effects of spin labels covalently bound to nucleic acids.

The sensitive biological assay for reverse transcriptase was used to monitor potential perturbation effects of spin labels covalently bound to various nucleic acids or nucleic acid analogs to the extent of about one label per 100 residues. The inhibitory properties of the spin labeled and unlabeled biopolymers were compared for evaluating possible interference of the reporter group in protein-nucleic acid interaction studies. The amount of inhibitor required for 50% inhibition (ED50) was determined for the competitive inhibitors (U)n, l(U)n, (RUGT,U)n, (Um)n, (A)n, (Am)n, and l(A)n as well as for thenon- or uncompetitive inhibitors (dUfl)n, l(dUfl)n, (dUz)n, and l(dUz)n. The most pronounced inhibition was observed with spin labeled and unlabeled (dUfl)n. The results indicate that the ED50 and the kinetic patterns of inhibition are similar for the spin labeled and unlabeled inhibitors studied. Thus, the presence of a limited number of spin labels in a nucleic acid matrix has little effect, if any, on reverse transcriptase-nucleic acid complexes and most likely on other protein-nucleic acid complexes.

Avian Myeloblastosis Virus↗
PubMed1976

Evidence for the presence of di- and triphospho pyridine nucleotide dehydrogenase derivatives as consistent contaminants of purified beef heart cytochrome-c oxidase.

Purified beef heart cytochrome-c oxidase preparations derived by three different laboratories contain NADH-K3 Fe (CN)6, NADH-nitrobluetetrazolium, and NADPH-nitrobluetetrazolium reductases. This is true of preparations exhibiting heme aa3 to protein ratios considered indicative of an excellent purity. An apparent association of cytochrome-c oxidase and one or more of the contaminants persists through immunodiffusion and nondenaturing electrophoresis and, in addition, in one instance copurification of NADH-K3Fe(CN)6 reductase and cytochrome-c oxidase to a constant ratio of specific activities was demonstrated. Cytochrome-c oxidase can be freed of the contaminants by equilibration with an NAD+-affinity matrix. As aconcomitant of equilibration with the matrix, the KM of cytochrome-c oxidase for ferrocytochrome-c is invariably decreased. Rat constants at low ferrocytochrome-c concentrations are consistently enhanced in all oxidase preparations upon equilibration with the NAD+ matrix. However, the effects of such equilibrations on the extrapolated Vmax varies from one preparation to another. Polyacrylamide gel electrophoresis in SDS-urea systems establishes that each of the preparations contains a minimum of three contaminants, each of an apparent formula weight of greater than 40,000 Daltons. NADH-NBT reductase was found to have a formula weight of approximately 46,000 Daltons. Their properties establish that NADH-K3Fe(CN)6 and NADH-NBT reductases are separate proteins; the separate identity of NADPH-NBT reductase has not yet been determined.

Animals↗
PubMed1976

[Experimental studies on the question of the enzymatic destruction of the ossicular bones during middle ear inflammations (author's transl)].

The proteolytic activity of purulent middle ear secretions from patients with cholesteatoma, chronic otitis media, acute otitis media and radical mastoid cavities were investigated. The proteolytic activity in the secretions from cases with cholesteatoma is higher than from patients with other chronic otitis media. The collagenolytic effect of the matrix of cholesteatoma combined with the high level of the bacterial and leukocytic proteinases in the middle ear secretions is undoubtedly one of the main factors in the destruction of the ossicular bones.

Cholesteatoma↗
PubMed1977

[Enzymatic properties of immobilized beta-galactosidase from Curvularia inaequalis].

beta-Galactosidase (EC 3.2.1.23) from fungus Curvularia inaequalis was modified by active brilliant orange KH and adsorbed on DEAE-Sephadex A-50. The lactose hydrolysis was studied in a continous flow on the column packed with the immobilized enzyme. The pH and temperatures optima for the substrate hydrolysis by the immobilized enzyme were shown to remain unchanged. A certain destabilizing effect of the matrix on the enzyme resistance to hear denaturation was observed. The activation parameters of denaturation of the native enzyme as well as those of the dye-modified and immobilized preparations were determined.

Chemical Phenomena↗