Decrease In Free Radicals Research Articles

Plasma-activated water pretreatment as a promising technique to reduce the formation of heterocyclic aromatic amines and advanced glycation end products in roasted fish patties

This study investigated the efficacy of using plasma-activated water (PAW) as a novel and additive-free pretreatment in reducing the formation of free and bound heterocyclic aromatic amines (HAAs) and advanced glycation end products (AGEs) in roasted fish patties. PAW activated for different durations (50 s, 100 s, and 150 s), significantly decreased the levels of HAAs and AGEs. The highest inhibition rates were observed at 35.44% and 19.82% for free and bound HAAs, respectively, and 42.76% and 23.23% for free and bound AGEs, respectively. PAW pretreatment reduced the formation of HAAs and AGEs and mitigated their increase during storage. Analysis using electron paramagnetic resonance and UPLC-MS/MS showed a decrease in free radicals and reactive carbonyls (phenylglyoxal, glyoxal, and methylglyoxal), which can serve as intermediates for HAAs and AGEs. Correlation analysis indicated a significant positive correlation between HAAs/AGEs and phenylacetaldehyde, glyoxal, methylglyoxal, and the total spin number (P < 0.05). This suggests that PAW suppresses the production of reactive carbonyls by quenching free radicals, thereby inhibiting the formation of HAAs and AGEs. In conclusion, with its additive-free approach, PAW pretreatment holds promise for reducing HAAs and AGEs and improving the safety of roasted fish products.

Toxicity of Metal Ions Released from a Fixed Orthodontic Appliance to Gastrointestinal Tract Cell Lines.

The mechanism of toxicity and cellular response to metal ions present in the environment is still a very current area of research. In this work, which is a continuation of the study of the toxicity of metal ions released by fixed orthodontic appliances, eluates of archwires, brackets, ligatures, and bands are used to test the prooxidant effect, cytotoxicity, and genotoxicity on cell lines of the gastrointestinal tract. Eluates obtained after three immersion periods (3, 7, and 14 days) and with known amounts and types of metal ions were used. Four cell lines-CAL 27 (human tongue), Hep-G2 (liver), AGS (stomach) and CaCo-2 (colon)-were treated with each type of eluate at four concentrations (0.1×, 0.5×, 1.0×, and 2.0×) for 24 h. Most eluates had toxic effects on CAL 27 cells over the entire concentration range regardless of exposure time, while CaCo-2 proved to be the most resistant. In AGS and Hep-G2 cells, all samples tested induced free radical formation, with the highest concentration (2×) causing a decrease in free radicals formed compared to the lowest concentrations. Eluates containing Cr, Mn, and Al showed a slight pro-oxidant effect on DNA (on plasmid φX-174 RF I) and slight genotoxicity (comet assay), but these effects are not so great that the human body could not "resist" them. Statistical analysis of data on chemical composition, cytotoxicity, ROS, genotoxicity, and prooxidative DNA damage shows the influence of metal ions present in some eluates on the toxicity obtained. Fe and Ni are responsible for the production of ROS, while Mn and Cr have a great influence on hydroxyl radicals, which cause single-strand breaks in supercoiled plasmid DNA in addition to the production of ROS. On the other hand, Fe, Cr, Mn, and Al are responsible for the cytotoxic effect of the studied eluates. The obtained results confirm that this type of research is useful and brings us closer to more accurate in vivo conditions.

The effect of hydroalcoholic extract of Cichorium intybus leaf on aryl hydrocarbon receptor expression in the testis of Wistar rats exposed to cigarette smoke.

Cigarette smoke (CS) contains compounds such as reactive oxygen species (ROS). Oxidative stress caused by excessive ROS eventually leads to germ cell apoptosis and male infertility. The leaves of Cichorium intybus (chicory) are rich in natural antioxidants, but their protective effects on the adverse effects of CS on testicular tissue have not been studied. 24 Wistar rats were classified into four groups: control, extract: treatment with chicory extract (200 mg/kg body weight/day) for 13 weeks, smoke: exposed to CS for 13 weeks, and smoke + extract: exposed to CS and treated with the C. intybus extract. Histological and biochemical analyses and apoptosis assay were done, and Ahr, and Cyp1a1 expression was determined. Treatment with C. intybus compensated for the reduction of Sertoli cells, spermatogonia, spermatocytes, and spermatids caused by CS. Chicory extract reduced free radicals and improved antioxidant status. The lowest and highest percentage of apoptotic cells was observed in the extract and smoke groups, respectively, while simultaneous treatment with C. intybus extract led to a significant reduction of apoptotic cells. The mean Ahr levels in the control, extract, smoke and smoke + extract groups were 1.00±0.57, 1.93±0.25, 5.98±0.42, and 0.62±0.22, respectively (p˂0.05). The mean levels of Cyp1a1 expression in the control, extract, smoke and smoke + extract groups were 1.00±0.31, 2.28±0.65, 5.55±0.40, and 0.21±0.23 (p˂0.05). The C. intybus extract probably affected Cyp1a1 expression by downregulation of Ahr. These led to a decrease in free radicals and apoptosis, and an improvement in antioxidant status.

Post-irradiation degradation of radio-oxidized natural rubber latex films induced by 60Co gamma rays

The present work involves the post-irradiation aging of radio-oxidized natural rubber latex (NRL) films irradiated by 60Co gamma rays. The NRL films underwent the two consecutive processes: irradiation oxidation in air with a dose of 0.1 kGy h−1 (pre-irradiation phase) and radiolysis in argon with a dose of 10 kGy h−1 (post-irradiation phase). The changes of oxygen-containing groups in radio-oxidized NRL films were subsequently analyzed by FTIR (ATR method), XPS, and Raman spectroscopy. Analysis of the EPR spectra of free radicals and macroscope properties (including mechanical and thermodynamic properties) were also carried out. Pre-irradiation of NRL films in air resulted in the rapid formation of various carbonyl and unsaturated carbonyl products related to aliphatic esters, ketones, and carboxylic acids. These were followed by the decomposition of the oxygen-containing functional groups in the post-irradiation phase. In particular, the formation of an enol tautomer of a β-diketone functionality was observed. The increase and decrease of free radicals by EPR analysis were closely related to the crosslinking and degradation of the NRL network structures induced by irradiation. Further analysis indicated that the variations in macroscopic properties of NRL films were attributed to the secondary reactions of free radicals. Mechanistic routes for these irradiation aging processes are proposed and discussed.

Ag nanoparticles synthesized using Lavandula angustifolia and their cytotoxic evaluation in yeast

Since silver nanoparticles (AgNPs) are currently found in many commercial products, knowledge of their toxicity in yeast cells is essential. Saccharomyces cerevisiae and Kluyveromyces marxianus are very similar to those of higher organisms such as mammals. Therefore, the cytotoxicity information obtained from these organisms can be related in a first approximation to human beings. In the present study, the Lavandula angustifolia plant extract was used as a reducing-stabilizing agent in the synthesis of silver nanoparticles. AgNPs cytotoxicity was evaluated in the yeast strains Kluyveromyces marxianus OFF1 and SLP1, and Saccharomyces cerevisiae MC4 and W303 by growth assay and colorimetric assay (MTT). The AgNPs were characterized by different techniques such as ultraviolet-visible spectroscopy (UV-Vis), infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The DPPH test showed an 80% antioxidant potential in the extract of the Lavandula angustifolia plant and showed a decrease in free radicals attributed to the reduction reaction of Ag+ to AgNPs. SEM and TEM showed AgNPs obtained with an average size of 18 nm and two types of morphologies, spherical and triangular. XRD patterns showed Ag solids with the fcc crystal structure. FTIR spectroscopies in conjunction with NMR confirmed that glycosylated flavonoids were responsible for the stabilization and reduction of NPs. A significant result from this study is that AgNPs did not show cytotoxicity on cell viability and growth inhibition on Kluyveromyces marxianus OFF1 and SLP1 strains, and Saccharomyces cerevisiae MC4 and W303. However, it was verified that those of the genus Kluyveromyces marxianus presented greater resistance to growth and cell viability.

Fucoidan: A nutraceutical for metabolic and regulatory systems homeostasis maintenance

Sustentation of homeostatic processes is the basic principle of vital activity of organism. Even small swings of concentration of some metabolites in the blood, especially glucose, lead to a violation of course of metabolic processes and pose a threat to vival activity of organism. Neuro-hormonal system, cytokine system and number of cell signaling systems participate in regulation of rate of metabolic processes. The influence of pharmaceutical preparations on these regulation systems can promote the development of serious complications, so there is an active search of natural food compounds with high bioactivity. The greatest interest in this situation is fucoidan, which is sulfated polysaccaride of brown seaweed. It is shown that it 1) supports the work of the central nervous system by moderately reducing the death of cholinergic neurons and maintaining the level of dopamine, 2) interferes with the development of hormonal imbalance, 3) promotes a decrease in the level of inflammatory cytokines in the blood and maintenance of the concentration of proinflammatory, 4) improves the functioning of the insulin cascade signaling systems at the mTOR kinase level by activating the translation process, 5) leads to a decrease in free radicals (antioxidant) and the restoration of their level (a prooxidant), 6) supports the homeostasis of the coagulation system due to anticoagulant and procoagulant properties. In this way, fucoidan should be attributed to nutraceuticals that promote health, improve quality and longevity of a person.

Radical dendrimers: Synthesis, anti-tumor activity and enhanced cytoprotective performance of TEMPO free radical functionalized polyurethane dendrimers

Polyurethane dendrimers up to fourth generation, functionalized with stable 4-hydroxy-2, 2, 6, 6-tetramethylpiperidin-1-yloxyl (4-hydroxy TEMPO), were prepared via a single-step urethane interchange reaction and their structures were confirmed by NMR, FT-IR, MALDI-TOF MS and SEC-MALLS techniques. The terminal TEMPO radicals of the dendrimers exhibited a triplet with nitrogen hyperfine splitting constant of 14.4 G, at g = 2.0026 in the EPR spectrum and their paramagnetic nature were confirmed by vibrating sample magnetometer. The MTT assay results revealed that the G4 dendrimer had significant anti-tumor activity in A549 lung adenocarcinoma cells and this dendrimer was found not induced any cell death in normal L132 lung cells. Further, antioxidant effect of G4 dendrimer was evaluated in normal L132 lung cells; the in-vitro studies include cell morphological studies, measurement of total intracellular reactive oxygen species (ROS) using H2DCF dye and analysis of SOD, CAT, GSH and GPx. This study demonstrated the efficacy of the dendrimers through decrease in free radicals and confirmed their enhanced cytoprotective performance over N-acetyl cysteine standard used.

PENINGKATAN KUALITAS MINYAK JELANTA MENGGUNAKAN KARBON AKTIF DAN EKSTRAK PUCUK IDAT (Cratoxylum glaucum)

Silica Waste cooking oil can be used as a soap or biodiesel. Good soaps or biodiesel should be from oils that have low levels of fatty acids and free radicals. However, waste cooking oil has high free fatty acid and free radical, it is necessary to increase the quality of waste cooking oil. One effort to improve the quality of waste cooking oil can use activated carbon as an adsorbent. Decrease in free radicals in cooking oil can use antioxidants from extract pucuk idat (Cratoxylum glaucum). This study aims to see the effect of extract pucuk idat on the process of improving the quality of waste cooking oil. The process of improvement by adding activated carbon and varying the concentration of ethanol extract pucuk idat. Activated carbon used 10% with variation of extract 0,25%; 0,5% and 0,75%. This process followed by stirring for 15 minutes at 80°C, then soaked for 3 days. Oil quality are identified by the method of determining the levels of free fatty acids and acid numbers. The results of this study indicate that extract pucuk idat in ethanol with 0,75% concentration has the lowest free fatty acid and acid number. Extract pucuk idat can improve the quality of waste cooking oil.

Effects of 1,2,3,4-Tetrahydroisoquinoline Derivatives on Dopaminergic Spontaneous Discharge in Substantia Nigra Neurons in Rats

1,2,3,4-Tetrahydroisoquinoline (TIQ) and its derivatives, 1-methyl-TIQ (1-MeTIQ) and 1-benzyl-TIQ (1-BnTIQ), are endogenously present in the human brain. In this study, we compared the effects of TIQ derivatives on spontaneous nigral dopaminergic discharge in rats treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). In the low-to-middle dose range (0.01-1 mg/kg), intravenous administration of MPTP induced a transient and potent increase in the firing rate. TIQ (0.01-30 mg/kg) had no effects, and 1-MeTIQ and 1-BnTIQ (0.01-10 mg/kg) produced a weaker increase in the firing frequency immediately after intravenous administration. Pretreatment with 1-MeTIQ (80 mg/kg, i.p.) significantly inhibited the decrease in dopaminergic spontaneous firing induced by a high dose of MPTP. The nigral induction of thiobarbituric acid-reactive substances (TBARS) by MPTP was also significantly suppressed by pretreatment with 1-MeTIQ. These results suggest that the neurotoxicity induced by TIQ derivatives is relatively weak compared to that induced by MPTP. The neuroprotective effect of 1-MeTIQ from MPTP-induced toxicity may be partially due to a decrease in free radicals, as suggested by a decrease in TBARS. This action presumably prevents cell membrane degeneration.

In vivo healing potential of Aegle marmelos in excision, incision, and dead space wound models.

The study incorporates the wound healing potential of Aegle marmelos fruit pulp extract (AME) on excision, incision, and dead space wound models in rats. AME (200 mg/kg) was administered orally once daily for variable days depending on the type of wound ulcer study. AME was studied for its wound breaking strength (incision wound), rate of contraction, period of epithelization and histology of skin (excision model), and granulation tissue free radicals, antioxidants, acute inflammatory marker, and connective tissue markers and deep connective tissue histology (dead space wound). Complete wound contraction and epithelization were observed at the 20th day after treatment with AME as compared to the 24th day in control rats. Mean epithelization period and scar area were decreased while wound breaking strength was increased with AME compared with control. Granulation tissue showed increased levels of collagen determinants (33.7 to 64.4%, P < 0.001) and antioxidants (13.0 to 38.8%, P < 0.05 to P < 0.001), whereas markers of oxidative stress (55.0 to 55.6%, P < 0.001) and myeloperoxidase (21.3%, P < 0.001) were decreased in AME treated group. A. marmelos seems to promote wound healing by enhancing connective tissue formation and antioxidants status with decrease in free radicals and myeloperoxidase having tissue damaging effects.

Crosslinking of a Gelatin Solutions Induced by Pulsed Electrical Discharges in Solutions

This study uses discharges in solutions for the treatment of gelatin solutions in order to generate crosslinking. The effects of plasma on the properties of gelatin solutions were investigated, the latter including viscosity, amino acid contents, chemical analyses, and gel strengths. The results show that, after short duration plasma treatments (5–10 min), the viscosity of the gelatin solutions increased, while the concentration of OH· free radicals decreased. After adding ethanol to the gelatin solutions, a greater increase in viscosity, and a greater decrease in free radicals were found. This suggests that ethanol provides more free radicals that can promote the crosslinking of the gelatin solution during the plasma treatment, resulting in higher viscosity. The gel strength of the gelatin was greatly enhanced by the plasma treatment of the solution. The results regarding the free amino acid contents showed that the crosslinking degree of plasma‐treated gelatin was higher than that of the untreated gelatin. FTIR measurements show that after plasma treatment, the IR bands at 1 668 and 1 558 cm−1, corresponding to the amide I and II groups of gelatin, shifted to higher wavenumbers, i.e. 1 672 and 1 564 cm−1, respectively. This suggests that crosslinking has occurred between gelatin molecules. The results show that discharges in solutions may be able to induce crosslinking reactions in the gelatin. Electrical discharges in solutions can be chemical‐free, alternative crosslinking methods.

Oxidative stress in sickle cell disease

In the 18th century, Priestley, Scheele and Lavoisier discovered oxygen and reported its critical role and toxic effects in living organisms. In the last century, several studies highlighted the importance of biological oxidation for energy production by aerobic organisms, in defense and the elimination of drugs. Oxidation is mediated by oxidants and free radicals, generically called reactive oxygen species (ROS), are formed as a byproduct of the oxygen metabolism. Antioxidant enzymatic and non-enzymatic molecules play a crucial role in maintaining the balance of ROS; an imbalance may lead to attack on all the components of the cell, including proteins, lipids and DNA. Collectively, oxidative stress is described as an imbalance between oxidants/free radicals and antioxidants(1-3). Recently, several reports have suggested that oxidative stress is a complex mechanism rather than a simple imbalance between the production and elimination of ROS. Oxidants and free radicals are continuously produced in living organisms with endogenous and external sources such as oxygen and nitric oxide [reactive nitrogen species (RNS)]. An increase in the normal redox state of a cell causes toxic effects that may lead to cell and tissue damage. Furthermore, a decrease in free radicals may be harmful, due to their critical role in microbial defense, cell proliferation, apoptosis, migration, inflammatory gene expression and vascular matrix regulation. In addition, free radicals are increasingly recognized as vital messengers in cellular signal transduction in several organisms(3-5). Sickle cell anemia is an inherited blood disorder affecting approximately 5% of the world's population. This disease results from a mutation in the beta globin chain inducing the substitution of Val for Glu at position 6, shifting the isoelectric point of the protein(6). This single mutation induces the production of hemoglobin S (Hb S), which is abnormal and insoluble. Sickle cell disease promotes harmful pathological effects that includes sickling of erythrocytes, vaso-occlusion and ischemia-reperfusion injury. Increasing evidence points towards an oxidative stress response responsible for increased pathophysiology of secondary dysfunctions in sickle cell patients(7,8). Several molecular mechanisms have been proposed to contribute towards a high oxidative burden in sickle cell patients. Some of the mechanisms that disturb the redox state include, the excessive levels of free hemoglobin that catalyze the Fenton reaction(9),the recurrent ischemia-reperfusion injury promoting the activation of the xanthine-xanthine oxidase system(10) and higher autoxidation of Hb S generating superoxide anion radicals and hence hydrogen peroxide(11). Furthermore, a chronic proinflammatory response in sickle cell patients induced by constant recruitment of neutrophils and monocytes has been shown to play an important role in causing complications(12,13). ROS and RNS are not only potential markers of sickle cell disease severity but are also important targets for antioxidant therapies(14,15). Several reports have indicated lower levels of carotenoids, flavonoids, vitamins C and E and zinc (structural component of superoxide dismutase) in sickle cell anemia patients(14). Nevertheless, no measurable parameters in clinical studies have shown to ameliorate sickle cell disease in patients that received antioxidant supplementation(16). In contrast, the treatment of erythrocytes from sickle cell anemia patients with the flavonoid quercetin has been shown to provide protection against hemoglobin oxidation and other cellular modifications promoted by peroxides(17). Henneberg et al.(18) in this issue of the Revista Brasileira e Hematologia e Hemoterapia demonstrate the use of an unspecific probe (2'7'-dichlorfluorescein-diacetate) to qualitatively assess the intracellular redox state of erythrocytes from sickle cell anemia patients. The authors describe the effect of the flavonols quercetin and rutin to reduce intracellular oxidation promoted by peroxide formation in the cells by their established method. Moreover, an additional antioxidant effect was observed in erythrocytes of patients treated with hydroxyurea. Accordingly, further studies are necessary to understand the mechanistic aspects of free radicals and oxidants in sickle cell disease to improve therapies and find better diagnostic tools. The promising results by Henneberg et al.(18) in monitoring the redox state should encourage the investigation of potential biomolecules and antioxidant therapy for sickle cell treatment in combination with drugs that specifically target ROS/RNS production.

Enzymatic and non-enzymatic protective mechanisms in recalcitrant seeds of Araucaria bidwillii subjected to desiccation

The changes in several antioxidants as well as in the level of C-centered free radicals and thiobarbituric acid reactive substances (TBARS) were studied in seeds of Araucaria bidwillii Hook desiccated to 37%, 28% and 21% moisture content. The lowest-safe moisture content for the seedling establishment was 37%. The embryo, besides double amounts of free radicals, showed higher levels of both enzymatic and non-enzymatic antioxidants than endosperm. Lutein decreased in both organs whereas α-tocopherol values were not affected by desiccation. In the embryo at 37% seed moisture content the antioxidant defense system increased giving rise to a decrease in free radicals. Beyond this point, free radicals and TBARS increased in agreement with the umpiring of the ascorbate/glutathione cycle by the decrease in reduced glutathione and glutathione reductase activity (GR, EC 1.6.4.2). At 21% moisture GR decreased. In the endosperm during desiccation, the consumption of ascorbate, total glutathione and lutein prevented the rise in free radicals and TBARS till 28% moisture, at which an increase in oxidized glutathione was also observed.

Impact of Organ Preservation Using HTK for Graft Flush and Subsequent Storage in UW in Rat Kidney Transplantation

Background: In kidney transplantation, preservation has a significant influence on organ function. Since previous reports have indicated a benefit of combining histidine-tryptophan-ketoglutarate (HTK) and University of Wisconsin (UW) solution, we evaluated the effects of initial flush with low viscosity HTK, followed by storage in UW. Material and Methods: Kidneys from inbred Lewis rats were procured using HTK or UW for initially perfusion and re-flushed after 30 min with either solution. In a third group, after perfusion with HTK, organs were re-flushed with UW. Organs were stored for 16–24 h (4°C). Study parameters were high-energy phosphates, histology, apoptosis, recipient survival and urine excretion of 15-F_2t-isoprostanes (oxidative stress marker). Results:Prior to transplantation, tissue ATP/ADP concentrations were: HTK/UW>UW-only >HTK-only. In transplanted kidneys, histological damage was highest after preservation in HTK-only. Twenty-four hours after transplantation (24 h cold ischemia time – CIT), cleaved-PARP was most abundant using UW-only. 16 h of CIT resulted in higher urine concentrations of isoprostanes in the order HTK-only (368 ± 308) > UW-only (157 ± 105) > HTK/UW (67 ± 26), and was lower in HTK/UW after 24 h of CIT (146 ± 38) vs. UW-only (507 ± 33 pg/mg creatinine). Survival (24 h CIT) was significantly reduced, and percentage of initial non-functioning (INF) kidneys highest in HTK-only (2.6 ± 0.3 days, 100%), compared to UW-only (13 ± 4.4 days, 75%) and HTK/UW (18.5 ± 4.6 days, 33%). Conclusions: In long-term preservation, UW is superior over HTK. However, our results indicate that perfusion with HTK prior to storage in UW may improve the results of UW alone which is reflected by better survival, lower rate of INF, higher cellular energy conservation and a decrease of free radicals.

Alcohol-induced free radicals in mice: Direct toxicants or signaling molecules?

Tumor necrosis factor α (TNF-α) and free radicals are produced in early alcohol-induced liver injury. Recently, pathology caused by alcohol was blocked nearly completely in tumor necrosis factor α receptor 1 (TNF-R1) knockout mice. With this model, it is now possible to evaluate whether free radicals are directly toxic or act as redox regulators of TNF-α production. Specifically, if free radicals were directly toxic, a parallel decrease in free radicals and pathology in TNF-R1 knockout mice would be predicted. If they only affect TNF-α production, radicals would be expected to remain high while pathology is diminished. Accordingly, free radical production in TNF-R1 knockout mice was studied here. The enteral alcohol delivery model used mice lacking TNF-R1 (p55) and wild-type control C57Bl/6J mice. Animals received a liquid diet continuously with either ethanol or isocaloric maltose-dextrin as control for 4 weeks. Urine ethanol levels fluctuated from 10 to 500 mg/dL in a cyclic pattern in mice receiving ethanol. Ethanol elevated liver:body weight ratios, serum alanine transaminase (ALT) levels, and pathology scores in wild-type mice. These parameters were blunted nearly completely in TNF-R1 knockout mice. Ethanol treatment increased free radical production in wild-type mice compared with animals fed a high-fat control diet. There were no differences in intensity of free radical signals regardless of the presence or absence of TNF-R1; however, pathology differed markedly between these groups. These findings are consistent with the hypothesis that free radicals act as redox signals for TNF-α production and do not directly damage cells in early alcohol-induced hepatic injury. (HEPATOLOGY 2001;34:935-942.)

Effect of high plasma free fatty acids on the free radical formation of myocardial mitochondria isolated from ischemic dog hearts.

Effects of high plasma free fatty acids (FFA) on the free radical formation of myocardial mitochondria, isolated from normal and ischemic dog hearts, were studied by electron spin resonance (ESR) spectrometry. Free radical concentrations in state 4 respiration were used for the evaluation of the function in the mitochondria in this study. High plasma FFA levels were induced either by intravenous injection of Intralipid and heparin, or by infusion of norepinephrine. Ischemic hearts were induced by inserting a Cournand's 7F catheter into the left coronary artery under fluoroscopic control. Exogenous high plasma FFA induced by Intralipid and heparin caused the decrease of free radicals in state 4 respiration in the mitochondria isolated from normal and ischemic dog hearts. Endogenous high FFA induced by continuous infusion of norepinephrine also caused the decrease of free radicals. On the other hand, nicotinic acid prevented the decrease of free radicals as well as the rise of plasma FFA by the norepinephrine infusion. These results suggest that high plasma FFA itself, whether it may be exogenous or endogenous, may impair the oxidative phosphorylation of the mitochondria isolated from normal and ischemic hearts.

Paramagnetic changes in cancer: Growth of Walker 256 carcinoma studied in frozen and lyophilized tissues

Samples of Walker 256 carcinoma grown in muscles of Sprague-Dawley rats were studied at low temperatures before and after lyophilization. The effects of lyophilization on the ESR spectra were different for tumours and normal muscle. Prior to lyophilization of a tumour sample, there was a decrease in free radicals, while after the lyophilization, there was an "increase". The "increase" was due to the lyophilized tumour having a narrower line, producing a greater peak-peak height measurement than in muscle, without an increase in the total number of spins. Exposure of lyophilized samples to air produced an increase in the intensity of the spectra and a change in line shape; also these effects differed for tumour and muscle. Mn++ levels were lower in tumour than in muscle, a difference eliminated by lyophilization. Poor growth conditions in tumours increased the occurrence of ESR spectra due to NO complexes with both heme and non-heme iron proteins. These results may help to resolve the principal controversies about experimental findings in ESR of tumours. At least part of the signals seen after lyophilization do not reflect free radicals in vivo. The signals after lyophilization reflect biochemical differences between tumour and muscle; spectroscopic data indicate that it is feasible to determine the molecular basis of these differences.