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Lysis

About: Lysis is a research topic. Over the lifetime, 6072 publications have been published within this topic receiving 216978 citations.


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Journal ArticleDOI
TL;DR: A close similarity was observed between the effects of Mg-depletion on sensitivity to EDTA and to polymyxin; a relationship between their mechanisms of action is suggested.
Abstract: SUMMARY: Pseudomonas aeruginosa grown under conditions of Mg-depletion in batch eulture in simple salts medium lost sensitivity to polymyxin B, causing lysis, release of 260 nm. absorbing materials and loss of viability. The patterns of lysis and leakage produced by polymyxin were similar with regard to the effect of growth in different Mg concentrations and the inhibitory effect of high polymyxin concentrations. The rates of lysis and leakage for any one suspension were similar. There was decreased polymyxin uptake by insensitive bacteria. Addition of Mg or one of several cations restored sensitivity both to polymyxin and to EDTA to varying degrees, but only after several cell divisions had occurred. A close similarity was observed between the effects of Mg-depletion on sensitivity to EDTA and to polymyxin; a relationship between their mechanisms of action is suggested. It is proposed that cations are essential for the synthesis of sensitive components of the envelope and may themselves be involved in the structure of the component.

86 citations

Journal ArticleDOI
TL;DR: A model of pyroptosis is proposed in which cell death can occur independently of cell lysis, which may allow for better control of cytosolic contents upon activation of the inflammasome.
Abstract: Although much insight has been gained into the mechanisms by which activation of the inflammasome can trigger pyroptosis in mammalian cells, the precise kinetics of the end stages of pyroptosis have not been well characterized. Using time-lapse fluorescent imaging to analyze the kinetics of pyroptosis in individual murine macrophages, we observed distinct stages of cell death and cell lysis. Our data demonstrate that cell membrane permeability resulting from gasdermin D pore formation is coincident with the cessation of cell movement, loss of mitochondrial activity, and cell swelling, events that can be uncoupled from cell lysis. We propose a model of pyroptosis in which cell death can occur independently of cell lysis. The uncoupling of cell death from cell lysis may allow for better control of cytosolic contents upon activation of the inflammasome.

85 citations

Journal Article
TL;DR: The murine CTL hybridoma PMMI was used, activated with PMA and ionomycin, to investigate possible alternate lytic pathways in CTLs in the absence of perforin, and it was found that PMMI is equipped with membrane TNF-alpha as a potential lytic mechanism, but T NF-alpha is unlikely to be involved in acute lytic reactions.
Abstract: The murine CTL hybridoma PMMI has been shown by the most sensitive techniques to be devoid of perforin. We thus used PMMI activated with PMA and ionomycin, to investigate possible alternate lytic pathways in CTLs in the absence of perforin. We found that PMMI is equipped with membrane TNF-alpha as a potential lytic mechanism, but TNF-alpha is unlikely to be involved in acute (4 h) lytic reactions. On the other hand, PMMI readily lyses target cells expressing the gene for the Fas Ag, but does not lyse target cells expressing fas antisense DNA. The generation of fas-dependent lysis required protein synthesis in PMMI, but target cell protein synthesis was not required for lysis. Lysis of Fas-positive target cells by PMMI was accompanied by DNA fragmentation, and both lysis and DNA fragmentation were blocked by inhibition of protein synthesis in the effector cell. We find the relative extent and kinetics of fas-dependent lysis and DNA fragmentation indistinguishable from that seen in "classical" CTL lytic assays. Both fas- and perforin-dependent lysis were blocked by inhibitors of poly(ADP) ribosylation. We found very little difference in the sequence of events in target cells lysed by the fas pathway compared with the classical (probably perforin) lytic pathway. Given the widespread distribution of fas, particularly in hematopoietic target cells, caution may be required in interpreting the relationship between parameters such as DNA fragmentation and 51Cr-release solely on the basis of the granule exocytosis model.

85 citations

Book ChapterDOI
TL;DR: Enzymatic lysis methods minimize denaturation, are scale independent, and allow some selectivity in the release of cellular products, but is of limited value for cell quantities in the 50-g to 1-kg range because of the difficulty in maintaining low temperatures.
Abstract: Publisher Summary Enzymatic lysis methods minimize denaturation, are scale independent, and allow some selectivity in the release of cellular products. The drawbacks to enzymatic methods include the large number of variables that can influence lysis and the addition of substances that may complicate subsequent purification steps. Degradation of the peptidoglycan in gram-negative cells is made more difficult by the presence of an asymmetric lipid bilayer. The outer membrane is external to the peptidoglycan and acts as a permeability barrier to large molecules. Thus, gram-negative bacteria are less susceptible than gram-positive bacteria to lysozyme and detergents. The factors influencing the efficiency of lysis include rate of agitation, cell concentration, concentration of glass beads, diameter of the beads, residence time in the chamber, and temperature. All these factors may need to be determined empirically. Sonication lyses cells by liquid shear and cavitation. Sonication remains a popular technique for lysing small quantities of cells, but is of limited value for cell quantities in the 50-g to 1-kg range because of the difficulty in maintaining low temperatures.

85 citations

Journal ArticleDOI
TL;DR: Depending on antibody specificity, complement may be deposited on the organism's surface to cause successful complement attack or may block complement attack induced by bactericidal antibody.
Abstract: The factors controlling lysis of gram-negative bacteria by complement are being investigated systematically. The first question was how smooth Salmonella minnesota, which has on its surface lipopolysaccharide with long O polysaccharide side chains, avoids lysis. Rough organisms are serum sensitive. In both smooth and rough organisms, complement components are deposited on the surface and the lytic sequence proceeds to completion. However, with serum-resistant organisms the membrane attack complex (MAC), composed of late-acting complement proteins, does not successfully insert into the outer membrane to cause membrane damage. At the completion of the lytic sequence, the hydrophobic MAC is shed. C3b, which directs late component assembly, is deposited on the longest O polysaccharide side chains on these smooth organisms, where it does not direct successful insertion of the MAC into the outer membrane. Serum-resistant gonococci sequester the MAC on the organism's surface in association with specific outer membrane components, where it does no damage to the outer membrane. Antibody appears to mediate site-directed complement component deposition in a number of systems. Thus, depending on antibody specificity, complement may be deposited on the organism's surface to cause successful complement attack or may block complement attack induced by bactericidal antibody. Monoclonal antibodies of the same isotype directed at different epitopes on the same bacterial surface antigen may either induce lysis or block lytic attack.

85 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023389
2022607
2021123
2020142
2019139
2018161