Release Of Cellular Constituents Research Articles

Effect of high-pressure treatment on oscillatory rheology, particle size distribution and microstructure of microalgae Chlorella vulgaris and Arthrospira platensis

Microalgae are rich in protein and bioactive compounds with a wide application in food, pharmaceutical, cosmetics and nutraceutical industries. However, the rigid cell wall remains the bottleneck for the extraction and release of cellular constituents in microalgae. High-pressure (HP) processing an athermal process has been explored to overcome the challenges. The objective of this study was to investigate the influence of high-pressure (HP) treatment (300–600 MPa/15 min) on the rheological, thermal, structural and particle size distribution of dry powdered form of two selected microalgae, namely Chlorella vulgaris (Chlorella) and Arthrospira platensis (Spirulina). HP-treatment of microalgae successfully transformed the liquid-like (G″ > G′) suspensional behavior to a solid-like (G′ > G″) gel by disrupting the cell wall of the biomass and denatured algal proteins. The gel rigidity (G′) increased with increasing the pressure from 300 to 600 MPa for both microalgae suspensions; however, the Spirulina exhibited the most significant improvement in the rigidity (6219 Pa) than the Chlorella (2340 Pa). HP-treatment at 300 MPa resulted in partial rupture of the Chlorella cell wall, which disintegrated completely at 600 MPa with exposure of the inner structure. The tubular shape of the Spirulina was not observed in the untreated sample; however, it appeared in the micrographs when the sample was treated above 300 MPa with the disintegration of the cellular mass. Chlorella had a bimodal particle size distribution (PSD) and the volumetric median particle size (Dv50) did not change significantly with the pressurization. Conversely, a unimodal PSD appeared in Spirulina and those particles were significantly affected by the pressure. The obtained information could be useful for food product development and tailoring the gel rigidity of the designed food products.

Effects of the peptide H-OOWW-NH2 and its derived lipopeptide C12-OOWW-NH2 on controlling of citrus postharvest green mold

The present study evaluated the antifungal properties of tetrapeptide H-OOWW-NH2 (O3TR) and its derivative lipopeptide C12-OOWW-NH2 (C12O3TR) against Penicillium digitatum, one of the main postharvest pathogens in citrus, and the possible mechanisms of their antifungal action. The results showed that the peptides O3TR and C12O3TR could inhibit conidial germination, induce conidia death and reduce the survival of mycelia of P. digitatum in vitro. The antifungal properties of O3TR and C12O3TR against P. digitatum were thermostable (40 °C–80 °C), insensitive to the change of pH (3–10) and varying sensitive to the presence of cations (Na+, Ca2+). In addition, the two peptides could effectively control green mold on citrus in vivo study. In terms of safety evaluation, the hemolytic activity of O3TR was neglectable, and significantly lower than that of C12O3TR, both of which were much lower than that of commercial prochloraz. The signals and intensity of fluorescent dye SYTOX Green (SG) and Propidium Iodide (PI) showed that O3TR and C12O3TR could enhance the mycelial and conidial membrane permeabilization. The antifungal action of O3TR and C12O3TR was further demonstrated by the release of cellular constituents and extracellular conductivity. In conclusion, the two peptides have a promising prospect to be applied as antifungal agents for the control of the green mold of citrus postharvest diseases.

Control of Citrus Post-harvest Green Molds, Blue Molds, and Sour Rot by the Cecropin A-Melittin Hybrid Peptide BP21.

In this study, the activity of the cecropin A-melittin hybrid peptide BP21 (Ac-FKLFKKILKVL-NH2) in controlling of citrus post-harvest green and blue molds and sour rot and its involved mechanism was studied. The minimum inhibitory concentrations of BP21 against Penicillium digitatum, Penicillium italicum, and Geotrichum candidum were 8, 8, and 4 μmol L-1, respectively. BP21 could inhibit the growth of mycelia, the scanning electron microscopy results clearly showed that the mycelia treated with BP21 shrank, formed a rough surface, became distorted and collapsed. Fluorescent staining with SYTOX Green (SG) indicated that BP21 could disintegrate membranes. Membrane permeability parameters, including extracellular conductivity, the leakage of potassium ions, and the release of cellular constituents, visibly increased as the BP21 concentration increased. Gross and irreversible damage to the cytoplasm and membranes was observed. There was a positive correlation between hemolytic activity and the concentration of BP21. These results suggest peptide BP21 could be used to control citrus post-harvest diseases.

Acute Kidney Injury due to Rhabdomyolysis Followed by Alcohol Intake and Physical Aggression: Case Report and Literature Review

Rhabdomyolysis is defined as a skeletal muscle injury, with subsequent release of cellular constituents into the extracellular fluid and the circulation. Several conditions can lead to rhabdomyolysis, and new causes are constantly expanded with new case reports. The aim of this paper is to report on a case of acute kidney injury (AKI) induced by rhabdomyolysis due to alcohol abuse and physical agression. A 48-year-old man was admitted to the emergency room with dyspnea, lower limbs edema, weakness, oliguria and dark brown urine. Four days before admission he was physically attacked, after drinking almost 2.5 liters of beer. The diagnosis of AKI due to rhabdomyolysis was made through clinical and laboratory findings (creatine kinase 184,376 IU/l, serum urea 275 mg/dL, creatinine 14.6 mg/ dL, potassium 7.9 mEq/L). Urgency hemodyalisis was started due to anuria, refractory hiperkalemia and hypercatabolism. Recovery of renal function was recorded, after fourteen hemodialysis sessions. Patients with rhabdomyolysis are common in the emergency room. Initial therapy of fluid replacement is essential to prevent progression to renal failure. Once established, the dialysis is indicated early. The prognosis is good, when early supportive therapy is adequate. DOI: http://dx.doi.org/10.3329/jom.v13i2.12759 J Medicine 2012; 13 : 212-215

The interaction of phenolic compounds with bacteria. I. Hexylresorcinol and Escherichia coli.

Abstract Various quantitative aspects of the interaction of hexylresorcinol with E. coli suspensions are described. The amounts of hexylresorcinol bound by the bacteria from solutions of varying concentrations were determined and the speed of this reaction and the influence of temperature on the extent of binding examined. The release of cellular constituents from the bacteria and the changes in the light-scattering properties of E. coli suspensions on addition of hexylresorcinol were also investigated. These results are discussed in relation to the site of antibacterial action of hexylresorcinol.

RELEASE OF PHOSPHORUS-32-CONTAINING COMPOUNDS FROM MICROCOCCUS LYSODEIKTICUS TREATED WITH CHLORHEXIDINE.

Abstract Chlorhexidine has been shown to cause the release of cellular constituents from phosphorus-32 labelled cells of Micrococcus lysodeikticus suspended in distilled water or in phosphate buffer. An initial rapid release is followed by a slower secondary release. This secondary release is inhibited by high concentrations of chlorhexidine. The release depends on the chlorhexidine to cell ratio and not on the absolute bactericide concentration.

The Interaction of Phenolic Compounds With Bacteria

Abstract The uptake of hexylresorcinol by suspensions of E. coli and the associated release of cellular constituents were examined using heat-killed and butanol-treated organisms. The effect of the addition of cetomacrogol to the system was evaluated in terms of the reduction in the extent of drug binding and the prevention of the hexylresorcinol-dependent light-scattering changes of E. coli suspensions. Sodium chloride potentiation of the latter effect and of the release of cell exudate from the bacteria on treatment with hexylresorcinol was also investigated.

Use of a one atmosphere uniform glow discharge plasma to kill a broad spectrum of microorganisms

The medical, industrial, and food processing industries are constantly in search of new technologies to provide improved methods of sterilization and pasteurization. Proposed techniques must deal with such problems as thermal sensitivity and destruction by heat, formation of toxic by-products, cost, and inefficiency in performance. We report results from a newly invented plasma source, a one atmosphere uniform glow discharge plasma (OAUGDP), which is capable of operating at atmospheric pressure in air and providing antimicrobial active species at room temperature. OAUGDP exposures have reduced log numbers of bacteria (Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa), bacterial endospores (Bacillus subtilis and Bacillus pumilus), and various yeast and bacterial viruses on a variety of surfaces. These surfaces included polypropylene, filter paper, paper strips, solid culture media, and glass. Experimental results showed at least a ⩾5 log10 colony forming units (CFU) reduction in bacteria within a range of 15–90 s of exposure, whether the samples were exposed in conventional sterilization bags or exposed directly to the plasma. An exception to these very short exposure times were experiments with solid culture media in which 5 min of plasma exposure was necessary to produce ⩾5 log10 CFU reduction in bacterial counts. The effects of plasma treatment on bacterial cell structures were investigated by exposing cells to plasma for various durations and examining them by transmission electron microscopy. The results showed that cell breakage (lysis) occurred with the release of cellular contents. These data were consistent with spectrophotometric results in which the release of cellular constituents was measured as a change in ultraviolet absorption at 260 nm. With all microorganisms tested, a biphasic survival curve (logarithmic number of survivors versus time) was observed in plots of dose-response data. Differences in susceptibilities of microorganisms observed on various surfaces suggested that the degree of lethality was dependent upon the time of diffusion of active species through the medium to the organism and the makeup of the microbial cellular surface.

Trimethyltin stimulates protein kinase C translocation through receptor-mediated phospholipase C activation in PC12 cells.

Trimethyltin (TMT) is a potent neurotoxic compound that initiates a delayed neuronal cell death. Previously we have shown that TMT-induced cytotoxicity is associated with protein kinase C (PKC) translocation and activation. The present study investigates the mechanism underlying TMT-stimulated PKC translocation in PC12 cells. TMT exposure led to a rapid increase in intracellular levels of inositol 1,4,5-trisphosphate (IP3), a product of phospholipase C (PLC). This was significantly decreased by pretreating cells with antagonists to either the cholinergic muscarinic receptor (atropine) or the glutamatergic metabotropic receptor [(+)-alpha-methyl-4-carboxyphenylglycine; (+)-MCPG]. Furthermore, the rise in IP3 level was blocked by pretreating cells with a PLC inhibitor (U-73122) or by a combination of atropine and (+)-MCPG. This pretreatment also significantly decreased TMT-stimulated PKC translocation, indicating that TMT-mediated PKC translocation was related to PLC activation, presumably through formation of diacylglycerol, an endogenous activator of PKC and product of PLC. It is interesting that atropine and (+)-MCPG did not provide protection against TMT-induced cytotoxicity in these cells. However, these data suggest that TMT causes the release of cellular constituents that activate G protein-coupled receptors, ultimately leading to PKC translocation.

Population Reductions of Gram-Negative Pathogens Following Treatments with Nisin and Chelators under Various Conditions

When used in combination with chelating agents (EDTA, EGTA, citrate, phosphate), the bacteriocin nisin is effective for reducing populations of gram-negative bacteria in vitro. This study examined parameters (buffers, temperature presence of divalent cations) that affect nisin inhibition of Escherichia coli O157:H7 and Salmonella typhimurium. Approximately 7 log10 colony-forming units (CFU) per ml of E. coli and S. typhimurium were treated in PBS or MOPS buffers containing 50 μg/ml of purified nisin, alone or in combination with 500mM lactate, 100mM citrate, 50mM EDTA, and 1% (wt/vol) sodium hexametaphosphate (pH 7.0) at 37°C for 60 min or 5°C for 30 min. Surviving bacterial populations were compared to untreated controls (buffers without nisin). Data indicated that treatments with nisin in buffers resulted in reductions of 4.30 and 2.30 log10 CFU/ml of E. coli and S. typhimurium, respectively, as compared to untreated controls. Population reductions ranging from 2.29 to 5.49 log10 CFU/ml were observed when cells were treated with nisin and chelator combinations at either 37°C for 60 min or 5°C for 30 min. The addition of magnesium and calcium to buffers with nisin decreased inhibition. Data obtained from spectrophotometric experiments indicated that treatments were causing the release of cellular constituents. However, transmission electron microscopy (TEM) analyses were inconclusive, since cellular membranes did not appear to be disrupted.

Ca2+-free perfusion of isolated rat heart: early irreversible changes and discrepancy between functional impairments and release of cellular constituents.

The effects of repeated (10 X), brief Ca2+-free perfusions (20 to 120 s) on myocardial contractility, coronary flow and release of cellular constituents of isolated rat heart were investigated. Ten successive Ca2+-deprivations of 20 or 40 s had no irreversible influences on cardiac performance. Ca2+-deprivations, however, of 60 s or longer, resulted in a substantial depression of contractile activity during recovery, which effect was parallelled by the development of myocardial contracture. Both effects appeared to be additive in character (and thus irreversible) and were dependent upon the duration and number of Ca2+-deprivations. The effect on coronary flow was biphasic: after an initial, rapid increase coronary flow steadily declined and was almost normal at the end of the experiments. The release of cellular constituents into the coronary effluent only occurred during reperfusion with Ca2+ after Ca2+-free periods of 60 s or longer. This loss of cellular material from the heart was observed mainly after the first Ca2+-deprivation and was only small or even negligible during the subsequent Ca2+-deprivations. The overall release of cellular material was clearly dependent on the duration of the Ca2+-free period, but was badly related to the overall loss in contractile activity. It was concluded that a relatively brief Ca2+-free perfusion period may induce a small but irreversible damage to the heart. This damage becomes visible, and more deleterious, when the brief Ca2+-washout is repeated several times. In addition, it was concluded that Ca2+-free-induced functional impairments and the release of cellular constituents of the heart are badly correlated and may be caused by two separate, but probably interrelated, mechanisms.

Magnesium and the calcium paradox: the occurrence of "spasmodic contractions" during Ca2+-Mg2+ -free perfusion of isolated rat heart.

The effects of omission of Mg2+ during Ca2+-free perfusion (3 min) of either spontaneously beating and electrically stimulated rat hearts were studied. Ca2+-free perfusion per se induced cardiac arrest and coronary vasodilation, and increased intrinsic pulse rate of the heart. Upon reperfusion with Ca2+, cardiac function was lost and parallelled by a sudden and massive release of cellular constituents ("calcium paradox"). Mg2+-free perfusion evoked effects opposite from Ca2+-free, with exception of heart rate which was increased. During Ca2+-Mg2+-free perfusion the electrocardiogram became irregular within 30 s, and this effect was followed by transient "spasmodic contractions". The effects of normal reperfusion were indistinguishable from those observed after Ca2+-free perfusion in the presence of Mg2+. Addition of Mn2+ or La3+ to the Ca2+-Mg2+-free perfusion medium completely inhibited the induction of electrical irregularities and spasmodic contractions. The typical effects of Ca2+-Mg2+-free perfusion are discussed in terms of Mg-Ca and Mg-K interactions at the sarcolemmal surface. It was concluded that our results may contribute indirectly to an explanation of the protective effect of high Mg2+-concentrations during Ca2+-free as well as ischemic perfusion of mammalian hearts.

Mechanisms of exocytosis

Publisher Summary This chapter elaborates a study analyzing mechanisms of exocytosis. Exocytosis is a method of discharge of secretory products in which there is selective release of granule-bound material. Other forms of secretion may cause nonselective release of cellular constituents. In the adrenal medulla, for instance, elevated pH causes the release not only of catecholamines but also of a cytoplasmic marker, lactic dehydrogenase (LDH). This is probably indicative of cell damage. Reserpine can release catecholamines without discharge of other soluble granule constituents. This represents another mechanism of catecholamine release and is also different from exocytosis. Evidence that exocytosis occurs in the adrenal medulla in response to the physiological transmitter, acetylcholine, and other drugs have been reviewed. This chapter discusses some of the factors believed to be involved in exocytisis in the adrenal medulla. The chapter highlights that inhibitors of ATP synthesis increase the spontaneous release of catecholamines from the adrenal gland, while inhibiting the evoked release. These findings have been interpreted along with the evidence that ATP activates calcium uptake by cell organelles and that ATP can release catecholamines from isolated chromaffin granules.

Release of Cellular Constituents During Heat Inactivation of Endospores of Aerobic Bacilli

SUMMARYRelease of dipicolinic acid from spores of some species of Bacillus during heating at 100°C was determined. The total amount and rate of release of dipicolinic acid from these spores varied between species and strains, the most resistant spores releasing the least. Studies were made on Bacillus polymyxa and B. megaterium to determine the influence of buffers and pH on the liberation of dipicolinic acid, carbohydrate, and nitrogen. Release of these materials was usually least at pH 7.0 and greatest under conditions that favored thermal inactivation. Some of the amino acids and carbohydrates released were identified.

Toxic and anti-sodium action of thromboplastic extracts of skin and muscle in burn and tourniquet trauma in mice

When mice subjected to standard thermal trauma received intraperitoneally small amounts of cell-free extracts of skin, muscle or brain with demonstrable thromboplastic activity, or heated extracts without thromboplastic activity, the mortality was enhanced in the first 8–12 hours postburn and the protective effect of administered saline was negated. When the volume of saline was increased progressively, the protective effect of the saline was counteracted by small amounts of tissue extract. Administration of heparin (which is capable of neutralizing the toxicity of skin extract injected intravenously) did not modify this delayed effect of skin extract. The data are interpreted to indicate that tissue trauma caused the release of cellular constituents (thromboplastin and others not yet identified) similar to those obtained from skin or muscle by homogenization with saline or water. Elucidation of the mechanism whereby these constituents of skin, muscle and brain cells produced these deleterious effects may enhance our understanding of the syndromes of both early and delayed death after severe burns and tourniquet injury.

CYTOPATHOGENIC EFFECT OF BRUCELLA SPHEROPLASTS ON MONOCYTES IN TISSUE CULTURE.

Freeman, Bob A. (The University of Chicago, Chicago, Ill.), and Barry H. Rumack. Cytopathogenic effect of Brucella spheroplasts on monocytes in tissue culture. J. Bacteriol. 88:1310-1315. 1964.-Mononuclear phagocytes from guinea pig peritoneal exudates were shown to ingest both normal Brucella suis and spheroplasts prepared from B. suis by treatment with glycine and with penicillin. Quantitative ingestion studies with P(32)-labeled Brucella showed that rough normal Brucella are ingested at a greater rate than are smooth normal Brucella. Spheroplasts prepared from smooth cells were phagocytized at a greater rate than were the normal smooth cells, and spheroplasts prepared from rough Brucella were phagocytized well, although apparently to a lesser extent than from the normal rough Brucella. The degree of phagocytosis of all spheroplasts appeared to reach a peak and then decrease, indicating a release of ingested bacteria; this release of intracellular bacteria is believed to be due to the cytopathogenic effect exerted by the spheroplasts. Direct microscopic observations showed that infection with living spheroplasts prepared from either smooth or rough Brucella destroyed a major portion of the host cells within 4 hr, but that formalin-killed spheroplasts were no more destructive than were normal Brucella. When host cell destruction was assayed by the release of cellular constituents into the medium, it was apparent that host-cell destruction by spheroplasts reaches a significant level within 0.5 hr after ingestion begins, and is almost complete by 4 hr. The implications of these findings in studies on the nature of intracellular Brucella are discussed.

Change in the viscosity of the medium after irradiation of bacteria with ultra-violet light.

BILLEN1 had earlier reported the release of cellular constituents from bacterial cells after irradiation with X-rays or with ultra-violet light. He carried out extensive qualitative determinations of the released cellular constituents in phosphate buffer-glucose medium. In this communication we record the change in viscosity of the eluted suspensions from the ultra-violet-irradiated bacterial cells.

Some Effects of Ultraviolet Irradiation on Yeast Cells (Candida utilis)

Effects of ultraviolet irradiation on yeast cells (Candida utilis) have been studied by ultraviolet photomicrography and by biochemical analysis of ultraviolet-absorbing cellular constituents. The results of these techniques have been correlated. Much larger doses of ultraviolet irradiation are required to produce morphological changes and altered membrane permeability than to stop the ability to form colonies. Morphological changes consist in enlargement of the vacuole, followed by a decline in cell size, and, eventually, coagulation of cellular protein. The vacuolar membrane loses its selective permeability in the same fashion as the cell membrane; vacuolar constituents are released into the cytoplasm and thence into the surrounding medium along with cytoplasmic constituents. The effect of ultraviolet irradiation is not immediate; after a sufficient dose, some time is required for the completion of the release of cellular constituents into the surrounding medium. There appears to be no selective specificity in the types of compounds released, because at 25 gas- cooled C essentially all material absorbing at 260 m is lost by the cells if the exposure to ultraviolet irradiation has been high enough. (auth)