Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P30536 (PBS)
 9,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Platelet-rich plasma in acidic-citrate-dextrose anticoagulant was kept for 5 days in an oxygen-permeable bag at 22 degrees C in an incubator/rotator. Platelet count remained stable throughout the experiment. On days 0, 3 and 5, aliquots were removed; platelets were isolated by centrifugation at 22 degrees C, 1500 g for 20 min, reconstituted to the original volume with PBS buffer, and the contents of alpha-granules were released by repeated freezing and thawing. Epidermal growth factor (EGF) and beta-thromboglobulin (beta-TG) in the platelet-poor plasma and platelet lysates were determined by radioimmunoassays. Results indicated that in platelet-free plasma, both total EGF and beta-TG increased 3-5-fold after 5 days; this amount represented 10-20% of the factors stored in the platelets. Correspondingly, the EGF and beta-TG contents of the platelet lysates exhibited accompanying decreases. HPLC fractionation showed that the main EGF fraction which progressively decreased in the lysates and increased in plasma had a molecular mass of 140 kDa. The contents of the 67 kDa and 6 kDa fractions did not change substantially. We conclude that under these conditions, the 140 kDa fraction was released preferentially. In view of these and previous experiments, it seems likely that different organs contribute to plasma EGF fractions.
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PMID:Release of different fractions of epidermal growth factor from human platelets in vitro: preferential release of 140 kDa fraction. 153 7

The cytotoxic effects of alloxan are not understood in any great detail, although they are considered to involve reactions mediated by oxygen-derived free radicals. These reactive species may form extra-or intracellularly following alloxan reduction, and result in cell damage through a number of complex interactions with a variety of macromolecules. The purpose of the present study was to elucidate further the early intracellular effects of alloxan on a model system of macrophage-like cells in culture. Addition of alloxan (15 mM), without reducing agents, to the medium surrounding the cells (phosphate-buffered saline, PBS, 37 degrees C, pH 7.4) resulted in rapid lysosomal damage (disappearance of the proton gradient over the membrane) followed by severe cellular degeneration (swelling and blebbing) and 50% cell death (trypan blue dye exclusion test) within fifty min. Cells pretreated with the gamma-glutamyl cysteine synthetase-inhibiting agent BSO, to decrease levels of intracellular glutathione, showed enhanced sensitivity to alloxan. The results are interpreted as indicating the cytotoxicity to result from intracellular formation of superoxide radicals, hydrogen peroxide and hydroxyl radicals, the latter within secondary lysosomes containing trace amounts of reactive iron (inducing Fenton reactions). The ensuing lysosomal membrane damage may result in leakage of lysosomal hydrolases and further cellular degeneration.
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PMID:Alloxan cytotoxicity involves lysosomal damage. 158 Oct 39

Alloxan participation in extracellular redox processes results in the formation of the reactive oxygen species (ROS) superoxide anions (O2-), hydroxyl radical (OH.) and hydrogen peroxide (H2O2), causing cell damage through a number of complex interactions probably involving several different cellular structures. These involve the plasma membrane, and we have recently presented evidence for lysosomal interference. The present study elucidates the early (within 15 min) events in a model system of macrophage-like cells (J-774) in culture. Addition of 2 mM alloxan and 1 mM cysteine to the medium surrounding the cells (phosphate-buffered saline, PBS, 37 degrees C, pH 7.4) resulted in rapid lysosomal membrane damage with disappearance of the proton gradient as visualized by acridine orange relocalization, as well as plasma membrane alterations leading to increased leakage of fluorescein after fluorescein diacetate staining. These events were later (greater than 30 min) followed by cellular degeneration in the form of blebbing. Mitochondrial damage (rhodamine 123 relocalization) was a late event. Cells pretreated with desferrioxamine (Des) and superoxide dismutase (SOD) or Des, SOD and catalase (CAT) to induce partial (H2O2 formation only) or almost full protection (no ROS formation) showed about the same reactions as when cells were exposed to alloxan and cysteine without scavengers (O2-, H2O2 and OH. formation) or with PBS only, respectively. The results are interpreted as indicating that the cytotoxicity is a consequence mainly of H2O2 involvement and probably of lysosomal influx of H2O2 with ensuing OH.formation within secondary lysosomes containing trace amounts of reactive iron. It is suggested that the resultant lysosomal membrane damage is followed by leakage of lysosomal hydrolases and ensuing cellular degeneration.
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PMID:Extracellular reduction of alloxan results in oxygen radical-mediated attack on plasma and lysosomal membranes. 158 Oct 40

Several lines of evidence indicate that oxidized LDL (Ox-LDL) may promote atherogenesis. Hence, the role of antioxidants in the prevention of LDL oxidation needs to be determined. beta-Carotene, in addition to being an efficient quencher of singlet oxygen, can also function as a radical-trapping antioxidant. Since previous studies have failed to show that beta-carotene inhibits LDL oxidation, we re-examined its effect on the oxidative modification of LDL. For these studies, LDL was oxidized in both a cell-free (2.5 microM Cu2+ in PBS) and a cellular system (human monocyte macrophages in Ham's F-10 medium). beta-Carotene inhibited the oxidative modification of LDL in both systems as evidenced by a decrease in the lipid peroxide content (thiobarbituric-acid-reacting substances activity), the negative charge of LDL (electrophoretic mobility) and the formation of conjugated dienes. By inhibiting LDL oxidation, beta-carotene substantially decreased its degradation by macrophages. beta-Carotene (2 microM) was more potent than alpha-tocopherol (40 microM) in inhibiting LDL oxidation. Thus, beta-carotene, like ascorbate and alpha-tocopherol, inhibits LDL oxidation and might have an important role in the prevention of atherosclerosis.
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PMID:beta-Carotene inhibits the oxidative modification of low-density lipoprotein. 195 40

alpha-Tocopherol contained in human blood cells was oxidized by a photosensitized reaction in the presence of hematoporphyrin as a photosensitizer. Participation of singlet molecular oxygen, superoxide radical and hydrogen peroxide in the photooxidation was not so significant, although hematoporphyrin can generate singlet molecular oxygen on illumination. Quercetin inhibited the photooxidation of alpha-tocopherol. Both in the presence and in the absence of linoleic acid, photooxidation of alpha-tocopherol which was suspended in the PBS solution was also inhibited by quercetin. The rate of the photooxidation of alpha-tocopherol in the presence of linoleic acid was faster than that in the absence of the fatty acid. When quercetin inhibited the photooxidation of alpha-tocopherol contained in blood cells or suspended in PBS solution, quercetin was oxidized. The photooxidation of quercetin, which was suspended in the PBS solution, was inhibited by alpha-tocopherol in the absence of linoleic acid, but stimulated in the presence of the fatty acid.
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PMID:[Effects of quercetin on photosensitized oxidation of alpha-tocopherol in human blood cells in the presence of hematoporphyrin]. 213 61

Cigarette smoke has been reported to contain free radicals and free radical generators in both the gas and particulate phases. Studies in our laboratory have shown that both cigarette smoke condensate (CSC) and smoke bubbled through phosphate buffered saline solution (smoke-PBS) increased sister chromatid exchanges (SCE) in Chinese hamster ovary cells in a dose-dependent manner. Since oxygen free radicals have been shown to cause SCEs and other chromosomal damage, we investigated the role of these radicals in the induction of SCEs by CSC and smoke-PBS. Addition of the antioxidant enzymes catalase and superoxide dismutase or the oxygen-radical scavenger ascorbic acid failed to reduce the SCE frequency in the presence of either CSC or smoke-PBS. Additional studies indicated that the quantity of hydrogen peroxide produced in CSC or smoke-PBS is too small to account for the observed SCE induction. It appears, therefore, that SCE induction by CSC or smoke-PBS does not involve the participation of oxygen free radicals.
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PMID:Role of oxygen free radicals in the induction of sister chromatid exchanges by cigarette smoke. 264 5

We investigated the effects of host inflammatory cells on the progression of QR (C57BL/6 mouse) and ER (SHR rat) regressor tumor cells which spontaneously regress in normal syngeneic hosts. We noted an enhanced tumorigenicity of regressor tumor cells after s.c. implantation with attachment to plastic plate, a situation which induces inflammation in normal hosts accompanied by the development of tumors as compared to normal mice injected with regressor tumor cells in suspension in PBS- which spontaneously regressed. We also observed enhanced tumorigenicity of regressor tumor cells injected into the site of the plastic plate which had been previously implanted into the normal host. Regarding these phenomena, we suggest that tumor progression may be induced by host induced inflammatory cells or their products. We also found enhanced tumor progression of QR regressor tumor cells after co-inoculation with inflammatory cells produced by the implantation of hemostatic spongel into the peritoneal cavity of mice. The mechanisms involved in the progression of regressor tumor cells by co-existence with inflammatory cells are thought to be associated with the production of oxygen radicals, tumor cell chemotactic factors, soft agar colony promoting factors and PGE2.
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PMID:[Experimental approach to the investigation of tumor progression]. 273 20

In this paper we report preliminary studies using alkaline elution to examine the incidence of DNA-strand breakage in human lung cells exposed to smoke/phosphate-buffered saline generated from cigarettes of different tar contents and filter status. The majority of the DNA breaks induced were abolished by catalase indicating a role for active oxygen species. The incidence of breaks did not correlate with the tar content of the cigarettes. The presence of a filter in the cigarette reduced the TPM concentration of the mainstream smoke but did not reduce the number of single-strand breaks occurring in DNA after exposure to smoke/PBS. This last parameter was however reduced if the filter was ventilated.
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PMID:Studies on the ability of smoke from different types of cigarettes to induce DNA single-strand breaks in cultured human cells. 277 Jul 60

This study was initiated for optimization of the environment of a technologically useful mammalian cell line for high density production. Cultures of Vero cells on microcarriers were perfused with 100%, 50%, 25% and 12.5% modified L15 media (galactose was replaced with 10 mM-fructose, with 4 mM-glutamine and 5% foetal bovine serum) in phosphate-buffered saline at either 4 or 8 vol. day-1. Cell growth, pH, dissolved oxygen, and changes in the metabolites, lactate to pyruvate and lactate to ammonia indices, demonstrated that under the conditions used in the present study, perfusion of cultures with 50% L15 medium in PBS at 8 vol. day-1 provided the optimum microenvironment for Vero cell growth. The highest cell density in the perfused cultures was 3 X 10(7) cells ml-1, which at these conditions was ten times higher than the maximum cell density (3 X 10(6) cells ml-1) obtained in a batch culture. Nutrient supply and conditioning factors were the most probable growth-limiting factors in cultures that were perfused with 12.5% and 25% L15 media, while multilayering, limitation of available oxygen, and accumulation of metabolic end products in the cellular microenvironment were the most probable causes of a density-dependent inhibition of cell growth observed under the optimized and overfed (supply of 100% L15 medium at the rate of 8 vol. day-1) culture conditions. Under the optimized environmental condition, the major source of energy was probably glutamine during the first week. However, significant utilization of fructose became evident at higher cell densities during the second week, when lactate production dramatically declined and reached an almost undetectable level, while respiration progressively assumed the predominant role in energy production. It is postulated that 'available' oxygen in the multicell-layered microenvironment of the optimized cultures was higher than in the overfed culture due to the greater utilization rate of oxygen for oxidation of excess nutrients in the overfed culture.
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PMID:Optimization of environment for high density Vero cell culture: effect of dissolved oxygen and nutrient supply on cell growth and changes in metabolites. 373 99

Pentobarbital anesthesia has been observed to increase markedly the effectiveness of respiration of oxygen at 3 atmospheres of pressure absolute to increase the response of early generation isotransplants of C3H mouse tumors to two-dose irradiation. A possible mechanism of this phenomenon is suppression of oxygen utilization by the pentobarbital and hence increasing mean pO2 and oxygen diffusion lengths. Measurements of QO2 of suspension of MCaIV and FSaII cells from freshly excised tumor tissue have been measured for cells suspended in PBS, Hank's buffered with HEPES +/- glutamate. The oxygen utilization by these tumor cells in vitro (when measured at congruent to 10 minutes after excision) is low, viz. 1 nmole/min/mg protein as compared with 6-9 nmoles/min/mg protein for established cell lines cultured in vitro. The suppression of QO2 by 2mM pentobarbital is less than 10%. This is a concentration of pentobarbital that is judged to be close to that which obtains in the tissues of the animals in the radiation response assays. Pentobarbital at .2mM did not change the cell survival characteristics of Chinese V79 cell spheroids irradiated in vitro. The results of these experiments do not indicate the suppression of oxygen utilization is an important contributor to the observed phenomenon of the increased response of tumors irradiated in mice respiring oxygen at high pressure. The role of hypothermia produced by the anesthesia is under further study.
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PMID:On the mechanism for enhancement of tumor radiation to hyperbaric oxygen in sodium pentobarbital anesthetized rodents. 653 7


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