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At least 955 records · Page 53Linked to original sources
PubMed2001

[The effect of acute hypobaric hypoxia on the autolytic changes in lipids of the gray and white substance of white rats].

Effects of acute hypobaric hypoxia (1:30 hrs. at 190-200 mm Hg) on the autolytic changes in lipids of the gray and white substance of the brain were evaluated in an experiment with white rats. Total lipids (TL) in the autolysing segments of the brain of rats sacrificed immediately following the end of hypoxia were noticed to undulate downward starting from minute 10 of incubation, whereas in the gray substance an insignificant TL loss occurred no earlier than in 4 hrs. with return to baseline values by the end of the observation (in 24 hrs.). Hypobaric hypoxia materially reduces phospholipids (PL) in these sections of the brain typically following 24 hrs. of autolysis with concomitant buildup of diglycerides (DG) and free fatty acids (FFA), and triglycerides (TG) in the white substance. There was also evidence of cholesterol (Ch) reduction both in the gray and white substances paralleled by buildup of cholesterol ethers (ChE) in the gray substance. However, after 24-hr incubation in the autolysing brain structures the total cholesterol displayed a strong trend upward. It is presumed that pre-exposure to hypobaric hypoxia enhances not only the hydrolytic PL degradation in the course of autolysis but also activates the transacylation-type rearrangements within the PL-DG-TG and PL-Ch-ChE in the white and gray substance of rat's brain.

Acute Disease↗
PubMed2006

[Validation studies of the test strip of colloidal gold-labeled anti-fibronectin EIIIA splicing variant for estimating the time of injury].

OBJECTIVE: To evaluate the validation of the test strip of colloidal gold-labeled anti-Fibronectin EIIIA(Fn-EIIIA) Splicing Variant for estimating the time of injury. METHODS: After skin tissues with variant injury times were collected from corpses, the test strip were used to detect the expression of Fn-EIIIA and its tested results were valued; The arisen autolysis which may influence the results of test were also observed by rats models. RESULTS: In no-injured skins, no Fn-EIIIA were detected by the strip, while in all the injured skins it was detected successfully as soon as injured after 1h and it showed more obvious results with the elongating of injured time; No changes made by autolysis were found in our studied time ranges. CONCLUSION: The test strip which used in this study showed to be a sensitive and steady method for estimating the time of injury in forensic science.

Alternative Splicing↗
PubMed1988

[Effect of arginine and its analogs on the activity of lysosomal and nonlysosomal peptide hydrolases in rat tissues].

The autolysis intensity and proteolysis activity at pH 4,5, 7,4, 8,5 and lysosomal and nonlysosomal peptide hydrolase activity have been studied in brain and liver tissues of rats. L-arginine has been found to increase the peptide hydrolase activity in neutral and alkaline media in case of autolysis and proteolysis estimation according to the amino nitrogen increase. When the peptide hydrolase activity is estimated according to the increase of folin-positive components its decrease under the action of arginine in neutral and alkaline media has been revealed. Arginine doesn't change the lysosomal peptide hydrolase activity. In both tissues under the influence of arginine the nonlysosomal peptide hydrolase activity defined by amino nitrogen increases, estimated by the folin-positive components--decreases. Arginine shows the specific influence on the nonlysosomal peptide hydrolase activity. The L-arginine analogues (D-arginine, guanidine) and products of the arginase reaction (ornithine and urea) don't exert such an effect on the nonlysosomal proteolysis.

Animals↗
PubMedDate not supplied

Function of the autotransplanted pancreatic segment in the dog.

Autotransplantation of the left lobe of the pancreas to the neck vessels was performed in 13 dogs. The technique employed made it possible to examine pancreatic secretion and arteriovenous difference in enzymes immediately after transplantation. Following functional examination the pancreatic duct was ligated. From 4 to 20 postoperative days the graft was intact only in 3 dogs. Severe autolysis of the graft and/or of the surrounding tissue developed in ten dogs 4 to 6 days after transplantation. Stimulation with secretin elicited immediate secretion response of the graft, the volume of secretion and output of amylase corresponding to normal values. A statistically significant arteriovenous difference was found both for amylase and LDH before and after secretin. Stimulation of exocrine secretion of the graft elicited a marked increase of enzyme concentration in the arterial and particularly in the venous blood of the graft. Cellular damage with subsequent leakage of enzymes into extracellular fluid plays a significant role in the pathogenesis of autolysis of the graft and surrounding tissues.

Amylases↗
PubMed1978

The generation of phospholipase A and hemolytic fatty acids by autolysing suspensions of Trypanosoma congolense.

When T. congolense undergoes autolysis there is a concomitant appearance of phospholipase A activity and hemolytic fatty acids. The generation of enzyme activity is exponential, and the appearance of hemolytic activity corresponds to a free fatty acid concentration of 0.02 to 0.03 mg. per ml. The concentration of the trypanosome suspension markedly affected the kinetics of the generation process. In contrast, the autolysis of T. lewisi did not generate hemolytic activity unless exogenous phospholipase A was added to the organisms.

Autolysis↗
PubMed1986

In vivo formation and stability of engineered disulfide bonds in subtilisin.

Computer modeling suggested that a disulfide bond could be built into Bacillus amyloliquefaciens subtilisin between positions 22 (wild-type, Thr) and 87 (Ser) or between positions 24 (Ser) and 87 (Ser). Single cysteines were introduced into this cysteine-free protease at positions 22, 24, or 87 by site-directed mutagenesis of the cloned subtilisin gene. The corresponding double-cysteine mutants were constructed, and recombinant plasmids were expressed in Bacillus subtilis. Double-cysteine mutant enzymes were secreted as efficiently as wild-type, and disulfide bonds were formed quantitatively in vivo. These disulfide bonds were introduced approximately 24 A away from the catalytic site and had no detectable effect on either the specific activities or the pH optima of the mutant enzymes. The equilibrium constants for the reduction of the mutant disulfide bonds by dithiothreitol were determined to be 82 +/- 22 and 20 +/- 5 for Cys22/Cys87 and Cys24/Cys87, respectively. Studies of autoproteolytic inactivation of wild-type subtilisin support a relationship between autolytic stability and conformational stability of the protein. The stabilities of Cys24/Cys87 and wild-type enzymes to autolysis were essentially the same; however, Cys22/Cys87 was actually less stable to autolysis. Reduction of the disulfide cross-bridge lowered the autolytic stability of both double-cysteine mutants relative to their disulfide forms. This correlates with a lowered autolytic stability for the Cys22 and Cys87 single-cysteine mutants, and the fact that an intramolecular hydrogen bond between the hydroxyl groups of Thr22 and Ser87 is likely to be disrupted in the Cys22 and Cys87 single-cysteine mutant proteins.

Autolysis↗
PubMed1985

Effect of pH on the morphology of Staphylococcus aureus.

Nineteen strains of Staphylococcus aureus (10 sensitive and 9 resistant to oxacillin) were grown for four hours on membranes placed on trypticase soy agar at pH 5, 5.5, 6, 6.5, 7.1, 7.5, 7.8 and 8.3. The morphology was observed by interference phase contrast and by electron microscopy. All strains grown at pH 6 to 7.5 produced cocci of normal size. When grown at pH 5, 5.5, 7.8 and 8.3, however, seven of the oxacillin-resistant strains and seven of the oxacillin-sensitive strains produced bacterial cells 1.5 to 2 micron in diameter. These cells consist of a cluster of staphylococci held together by multiple thick cross walls. Their structure is similar to that of staphylococci grown in the presence of subminimum inhibitory concentrations of beta-lactam antibiotics, which inhibit autolysis of cross walls. It appears that autolysis of cross walls of S. aureus is also inhibited by a low or a high pH.

Autolysis↗
PubMed1984

Functional studies on the secreted form of human C4 (C4s), two incompletely processed two-subunit C4 molecules (beta - alpha + gamma and beta + alpha - gamma), and pro-C4.

The functional properties of the secreted form of C4 (C4s), which has a Mr approximately 5000 greater than the predominant C4 molecule found in plasma (C4p), two incompletely processed two-chain C4 molecules (beta - alpha + gamma and beta + alpha - gamma), and the extracellular C4 precursor (designated pro-C4(E)] were evaluated. All four molecules are secreted in parallel by a human hepatoma-derived cell line (Hep G2). Secretion of hemolytically active C4 is linear up to approximately 12 hr, peaks at 24 hr, and then progressively decreases over the next 48 hr. This loss of C4s functional activity parallels the proteolytic conversion of C4s to C4bs. To compare the hemolytic efficiencies of C4s and C4p, a solid-phase competitive radioimmunoassay was developed to permit measurement of the small quantities of C4 antigen in these cultures. The hemolytic efficiencies of C4s and C4p were similar. These results indicate that extracellular processing of C4s to C4p does not modulate the hemolytic activity of the molecule. Consistent with their ability to bind methylamine, both the alpha s-chain and the alpha - gamma subunit undergo denaturation-induced autolysis. The extracellular and intracellular pro-C4 molecules are also sensitive to autolytic cleavage. Interestingly, the beta - alpha subunit is resistant to autolysis. In experiments in which C4s and C4p were cleaved by C1-s to C4bs, C4(beta - alpha + gamma), C4(beta + alpha - gamma), and pro-C4(E) were resistant to C1-s cleavage and thus hemolytically inactive relative to C4s. These data indicate that processing of C4 to a three-chain structure is required to provide the proper conformation for efficient activation by C1.

Animals↗
PubMed1984

Covalent structures of beta and gamma autolytic derivatives of human alpha-thrombin.

Nonclotting beta- and gamma-thrombins have been prepared by autolysis of human alpha-thrombin at pH 8.6 in the presence of 0.4 M NaCl and purified on BioRex 70. Reduced and carbamidomethylated A and B chains fragments were separated by gel filtration and reverse phase high performance liquid chromatography. Structural characterization of these fragments demonstrated that alpha to beta conversion results from two cleavages at Arg 62 and Arg 73 in the B chain, releasing an intact 11-residue peptide. beta to gamma conversion corresponds to the additional loss of a fragment of the B chain stretching from Ile 124 to Lys 154. Autolysis is not accompanied by cleavages in the A chain. Loss of clotting activity is therefore related solely to the excision of residues 63 to 73 in the B chain. With the exception of cleavage at Arg 73, these results differ from a proposed model for alpha to gamma conversion of bovine thrombin.

Amino Acid Sequence↗
PubMedDate not supplied

[Postmortem decomposition of skeletal muscle RNA].

RNAs, isolated from rat sceletal muscles by heat and cold phenol treatment within various periods after animal death, were analyzed by means of centrifugation in sucrose gradient. Content of 28 S RNA was found to be decreased by 7-8% within 3 days of autolysis with maintaining of the total ribosomal RNA yield. These data suggest that nucleases were present in microsomal and crude myofibrillar fractions and their activity was increased duing autolysis.

Animals↗
PubMed1996

Adipocere--problems in estimating the length of time since death.

Establishing the length of time since death is particularly difficult in corpses showing advanced autolysis. One sign of advanced decay is the formation of adipocere. In this state bodies show evidence of a partly wax-like and partly pasty condition. Continued storage ultimately results, among other things, in further decomposition due to the action of micro-organisms from the surrounding area-even if this is chronologically delayed. An exception is provided by the formation of adipocere under air-tight conditions. Initially, autolysis and heterolysis also occur, involving the release of fatty acids. As a result of the subsequent hydrogenation of the fats under the influence of bacterial enzymes, the unsaturated fatty acids are partially converted into saturated fatty acids. As the fatty acids clearly have a bactericidal effect, further bacterial decomposition is stopped at this early adipocere stage. Additional micro-organisms from outside can no longer penetrate when this hermetic seal is in place. In addition, the lack of calcium (e.g. from water or moist earth) can be a reason for the fact that further adipocere development, leading to wax-like hardening of the fat, is arrested. Thus the condition of the body can remain constantly preserved over many years and it no longer allows a reliable estimate to be made of the period of time since death.

Anaerobiosis↗
PubMedDate not supplied

[Physico-chemical and enzymatic properties of polymeric trypsin derivatives based on dextran].

The molecular weight distribution, thermal stability during autolysis, resistance to human serum inhibitors as well as temperature optimum of native and dextran-modified trypsin were investigated. The seeming constants of autolytic inactivation and inhibition of native and modified trypsin were calculated. Trypsin polymer derivatives had higher molecular weight than the native enzyme. They also showed higher resistance to autolysis and serum inhibitors. Possible causes of the above effects are discussed.

Autolysis↗
PubMed1997

Changes in calpain during meiosis in the rat egg.

Resumption of meiosis at fertilization is mediated by increased levels of calcium which activate several calcium-dependent enzymes. Calpain, a neutral calcium-activated thiol protease, is present in the cytoplasm of many cells. Its activation is associated with limited autolysis and relocalization in the cell. Calpain is thought to participate in the regulation of mitosis and resumption of meiosis in Xenopus oocytes. In this study we followed the activation and localization of calpain during maturation and fertilization in rat eggs using a polyclonal antibody raised against chicken muscle calpain. A band of 80 kDa was detected in GV oocytes and its level increased in unfertilized MII eggs. At the early stages of fertilization, we observed a transient decrease in the level of calpain which was regained at the pronuclear stage. Adding Ca2+ to lysate of MII eggs resulted in an additional band, representing the degraded fragment of the activated protein. In eggs activated by ionomycin, calpain level decreased, followed by an increase in a dynamic similar to that observed in fertilized eggs. Egg activation also led to changes in calpain localization. A homogenous distribution was observed in GV and in MII eggs, while in activated eggs it was localized predominantly overlying the metaphase plate. In the current study we demonstrate the presence of calpain in the rat egg. During maturation, calpain level increases; however, during egg activation, in response to [Ca2+]i changes, calpain undergoes autolysis, translocaton, and fluctuation in its level. We therefore suggest a correlation between calpain activation and fertilization.

Animals↗
PubMed1985

The auditory pathology of brain death as revealed by auditory evoked potentials.

A case of brain death is reported in which the auditory brainstem response, middle latency component, and slow vertex response were recorded before and after the cessation of cortical activity, and in which histological examination of the temporal bone and central auditory pathways was performed post mortem. Brain death of at least 48 hours' duration was demonstrated by neurological examination, flat electroencephalographic recording, and persistent absence of auditory evoked responses. The postmortem examination was performed 3 hours after death. The pathological studies of the whole length of the auditory pathway revealed total autolysis of the organ of Corti, marked cell loss in the dorsal cochlear nucleus, and moderate cell loss in other nuclei of the central auditory pathway. It should be considered that total autolysis of the organ of Corti and severe cell loss of the cochlear nucleus may occur if the auditory brainstem response becomes absent in comatose patients.

Adult↗
PubMed1982

Evolution of Sertoli cell processes invading the cytoplasm of rat spermatids.

Sertoli cell processes invaginating the cytoplasm of rat spermatids were investigated in thin or thick sections stained respectively with ferrocyanide-reduced osmium (Karnovsky, 1971) and the Ur-Pb-Cu metallic impregnation method (Thiéry and Rambourg, 1976). Two types of Sertoli cell processes were observed: Some, seen in steps 11-15 of spermiogenesis, were associated with a tight network of ER cisternae located within the spermatid cytoplasm subjacent to the plasma membrane facing the Seertoli cell process; others, seen from step 11 until the end of spermiogenesis, were not associated with such a spermatid subsurface ER network. Following their formation, the ER-associated Sertoli cell processes were cleaved into double-walled vesicles. Concomitantly, the enclosed Sertoli cell cytoplasm underwent autolysis followed by the dissolution of the Sertoli cell plasma membrane leaving within the spermatid cytoplasm many empty-looking vacuoles delimited only by the plasma membrane of the spermatid. Thereafter, i.e., in steps 15 and 16 of spermiogenesis, these vacuoles clustered, and with the collapse of the vacuoles they gave rise to a single compact mass of interlaced ER cisternae and small vacuoles. With the dissolution of ER cisternae, in step 18, this mass was finally dispersed. These observations suggested that the ER-associated Sertoli cell processes may constitute a pathway for the delivery of material from the Sertoli cells into spermatids. In contrast, the Sertoli cell processes not associated with a network of ER cisternae did not show cleavage or autolysis and appear to be involved mainly in holding the cytoplasm of the spermatid in place.

Acrosome↗
PubMed2007

Crosslinked enzyme aggregates in hierarchically-ordered mesoporous silica: a simple and effective method for enzyme stabilization.

alpha-chymotrypsin (CT) and lipase (LP) were immobilized in hierarchically-ordered mesocellular mesoporous silica (HMMS) in a simple but effective way for the enzyme stabilization, which was achieved by the enzyme adsorption followed by glutaraldehyde (GA) crosslinking. This resulted in the formation of nanometer scale crosslinked enzyme aggregates (CLEAs) entrapped in the mesocellular pores of HMMS (37 nm), which did not leach out of HMMS through narrow mesoporous channels (13 nm). CLEA of alpha-chymotrypsin (CLEA-CT) in HMMS showed a high enzyme loading capacity and significantly increased enzyme stability. No activity decrease of CLEA-CT was observed for 2 weeks under even rigorously shaking condition, while adsorbed CT in HMMS and free CT showed a rapid inactivation due to the enzyme leaching and presumably autolysis, respectively. With the CLEA-CT in HMMS, however, there was no tryptic digestion observed suggesting that the CLEA-CT is not susceptible to autolysis. Moreover, CLEA of lipase (CLEA-LP) in HMMS retained 30% specific activity of free lipase with greatly enhanced stability. This work demonstrates that HMMS can be efficiently employed as host materials for enzyme immobilization leading to highly enhanced stability of the immobilized enzymes with high enzyme loading and activity.

Chymotrypsin↗
PubMed2002

Nucleolin is a calcium-binding protein.

We have purified a prominent 110-kDa protein (p110) from 1.6 M NaCl extracts of rat liver nuclei that appears to bind Ca2+. p110 was originally identified by prominent blue staining with 'Stains-All' in sodium dodecyl sulfate-polyacrylamide gels and was observed to specifically bind ruthenium red and 45Ca2+ in nitrocellulose blot overlays. In spin-dialysis studies, purified p110 saturably bound approximately 75 nmol Ca2+/mg protein at a concentration of 1 mM total Ca2+ with half-maximal binding observed at 105 microM Ca2+. With purification, p110 became increasingly susceptible to proteolytic (likely autolytic) fragmentation, although most intermediary peptides between 40 and 90 kDa retained "Stains-All", ruthenium red, and 45Ca2+ binding. N-terminal sequencing of intact p110 and a 70-kDa autolytic peptide fragment revealed a strong homology to nucleolin. Two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE)/IEF revealed autolysis produced increasingly acidic peptide fragments ranging in apparent pI's from 5.5 for intact p110 to 3.5 for a 40 kDa peptide fragment. Intact p110 and several peptide fragments were immunostained with a highly specific anti-nucleolin antibody, R2D2, thus confirming the identity of this protein with nucleolin. These annexin-like Ca2+-binding characteristics of nucleolin are likely contributed by its highly acidic argyrophilic N-terminus with autolysis apparently resulting in largely selective removal of its basic C-terminal domain. Although the Ca2+-dependent functions of nucleolin are unknown, we discuss the possibility that like the structurally analogous HMG-1, its Ca2+-dependent actions may regulate chromatin structure, possibly during apoptosis.

Animals↗
PubMed1983

Lytic enzyme activity in autolysing mycelium of Aspergillus niger.

We have studied changes in the activity of some lytic enzymes contained in mycelium of Aspergillus niger in cultures relative to the autolytic phase of growth. Acid phosphatase, polygalacturonidase and alpha-amylase activity reached its highest level (40.7, and 8 U/sample, respectively) at the initiation of the autolytic phase of growth. 1.3-beta-Glucanase and beta-N-acetylglucosaminidase reached its highest level (3.5 and 2 U/sample, respectively) during the first days of autolysis. Alkaline phosphatase, cellulase, invertase, esterase, chitinase and proteolytic activity is also present in autolysing mycelium of A. niger, though comparatively low. Their maximum activity coincided with the beginning of the autolytic phase of growth. In all enzymes studied here, as autolyis proceeded, enzyme activity decreased by about 90%. Only esterase activity remained nearly constant throughout the whole period of autolysis described here.

Acetylglucosaminidase↗