Chemistry of deep-fat frying oils

Deep-fat frying produces desirable or undesirable flavor compounds and changes the flavor stability and quality of the oil by hydrolysis, oxidation, and polymerization. Tocopherols, essential amino acids, and fatty acids in foods are degraded during deep-fat frying. The reactions in deep-fat frying depend on factors such as replenishment of fresh oil, frying conditions, original quality of frying oil, food materials, type of fryer, antioxidants, and oxygen concentration. High frying temperature, the number of fryings, the contents of free fatty acids, polyvalent metals, and unsaturated fatty acids of oil decrease the oxidative stability and flavor quality of oil. Antioxidant decreases the frying oil oxidation, but the effectiveness of antioxidant decreases with high frying temperature. Lignan compounds in sesame oil are effective antioxidants in deep-fat frying.

Bax, but not Bcl-xL, decreases the lifetime of planar phospholipid bilayer membranes at subnanomolar concentrations

Release of proteins through the outer mitochondrial membrane can be a critical step in apoptosis, and the localization of apoptosis-regulating Bcl-2 family members there suggests they control this process. We used planar phospholipid membranes to test the effect of full-length Bax and Bcl-xL synthesized in vitro and native Bax purified from bovine thymocytes. Instead of forming pores with reproducible conductance levels expected for ionic channels, Bax, but not Bcl-xL, created arbitrary and continuously variable changes in membrane permeability and decreased the stability of the membrane, regardless of whether the source of the protein was synthetic or native. This breakdown of the membrane permeability barrier and destabilization of the bilayer was quantified by using membrane lifetime measurements. Bax decreased membrane lifetime in a voltage- and concentration-dependent manner. Bcl-xL did not protect against Bax-induced membrane destabilization, supporting the idea that these two proteins function independently. Corresponding to a physical theory for lipidic pore formation, Bax potently diminished the linear tension of the membrane (i.e., the energy required to form the edge of a new pore). We suggest that Bax acts directly by destabilizing the lipid bilayer structure of the outer mitochondrial membrane, promoting the formation of a pore-the apoptotic pore-large enough to allow mitochondrial proteins such as cytochrome c to be released into the cytosol. Bax could then enter and permeabilize the inner mitochondrial membrane through the same hole.

Nitric Oxide–Dependent Suppression of Thioredoxin-Interacting Protein Expression Enhances Thioredoxin Activity

Objective— Cellular redox balance is regulated by enzymatic and nonenzymatic systems and freely diffusible nitric oxide (NO) promotes antioxidative mechanisms. We show the NO-dependent transcriptional regulation of the antioxidative thioredoxin system.

Methods and Results— Incubation of rat pulmonary artery smooth muscle cells (RPaSMC) with the NO donor compound S -nitroso-glutathione (GSNO, 100 μmol/L) suppressed thioredoxin-interacting protein (Txnip), an inhibitor of thioredoxin function, by 71±18% and enhanced thioredoxin reductase 2.7±0.2 fold (n=6; both P <0.001 versus control). GSNO increased thioredoxin activity (1.9±0.5-fold after 4 hours; P <0.05 versus control). Promoter deletion analysis revealed that NO suppression of Txnip transcription is mediated by cis -regulatory elements between −1777 and −1127 bp upstream of the start codon. Hyperglycemia induced Txnip promoter activity (3.9±0.2-fold; P <0.001) and abolished NO effects (−37.4±1.0% at 5.6 mmol/L glucose versus 12.4±2.1% at 22.4 mmol/L glucose; P <0.05). Immunoprecipitation experiments demonstrated that GSNO stimulation and mutation of thioredoxin at Cys69, a site of nitrosylation, had no effect on the Txnip/thioredoxin interaction.

Conclusions— NO can regulate cellular redox state by changing expression of Txnip and thioredoxin reductase. This represents a novel antioxidative mechanism of NO independent of posttranslational protein S -nitrosylation of thioredoxin.

Characterization and quantification of anthocyanins in grape juices obtained from the grapes cultivated in Korea by HPLC/DAD, HPLC/MS, and HPLC/MS/MS

The characterization and quantification of anthocyanins in grape cultivars of Oll-Meoru (Vitis coignetiaexVitis labrusca), Neut-Meoru (Vitis coignetiaexVitis labrusca), Muscal Bailey A. (Vitis labruscana), and Campbell Early (Vitis labruscaxV. vinifera) cultivated in Korea were carried out by partial purification through XAD-7 column chromatography followed by C-18 HPLC/diode array detector (DAD), HPLC/MS, and HPLC/MS/MS analyses. The column oven temperature during the reverse phase C-18 HPLC greatly affected the separation of individual anthocyanins. The result showed that the optimum column oven temperature was 35 degrees C. Sixteen different anthocyanins (11 nonacylated and 5 acylated anthocyanins) were identified in the grape juices. Oll-Meoru, Neut-Meoru, and Muscat Bailey A (MBA) grape juices contained only nonacylated anthocyanins. Oll-Meoru and Neut-Meoru grape juices had same anthocyanins, but their proportions were considerably different. Peonidin 3,5-diglucoside and malvidin 3,5-diglucoside were the major anthocyanins in Oll-Meoru grape juice. Delphinidin 3-glucoside was, however, the major anthocyanin in Neut-Meoru grape juice. Peonidin 3-glucoside and malvidin 3-glucoside were the most abundant anthocyanins in Muscal Bailey A grape juice. Campbell Early grape juice contained both nonacylated and acylated anthocyanins. Cyanidin 3-(p-coumaroyl)glucoside-5-glucoside and peonidin 3-(p-coumaroyl)glucoside-5-glucoside were the most abundant anthocyanins in Campbell Early grape juice. Total anthocyanin contents were greatly different in different grape jucies, with the highest in Neut-Meoru juice (1043.5 microg/mL), followed by Oll-Meoru (997.7 microg/mL), MBA (390.2 microg/mL), and Campbell Early (183.9 microg/mL) juices. The total anthocyanin content in Neut-Meoru grape juice was 5.67 times higher than that in Campbell Early grape juice. This represents the 1st report on the systematic characterization and quantification of anthocyanins in the juices of these grapes cultivated in Korea.

Positive end-expiratory pressure decreases mesenteric blood flow despite normalization of cardiac output

Positive end-expiratory pressure (PEEP) is a commonly used adjunct to mechanical ventilation and is known to have deleterious effects on cardiac output (CO). Its effects on regional blood flow are not well known. We evaluated the effect of PEEP on the mesenteric microcirculation and CO. Sprague-Dawley rats were treated with mechanical ventilation and either no PEEP (Control) or increasing levels of PEEP (PEEP). Using in vivo video-microscopy, mesenteric A1 arteriolar optical Doppler velocities and A1 and A3 (the first- and third-order arterioles branching off the feeding mesenteric arcade) intraluminal diameters were measured (n = 6/group). In a separate set of experimental animals, CO was determined by thermodilution technique (n = 5/group). Additionally, after the PEEP group attained a PEEP level of 20-cm H2O PEEP, two boluses of 2 mL 0.9 normal saline (NS) were given intravenously. The Control groups had the same determinations performed over the same time course as the PEEP group but were not exposed to any PEEP. Mesenteric blood flow (MBF) was calculated from vessel diameter and red blood cell velocity. The MBF and CO fell progressively as PEEP was increased from 10- to 15- to 20-cm H2O pressure. MBF was reduced 75% (p < 0.05) and the CO was reduced 31% (p < 0.05) from baseline at 20-cm H2O pressure PEEP. After 4 mL normal saline, the MBF was still 45% below baseline (p < 0.05) while the CO had returned to baseline. In conclusion, both MBF and CO are decreased significantly with increasing PEEP.(ABSTRACT TRUNCATED AT 250 WORDS)

Singlet oxygen quenching effects of phosphatidylcholine in emulsion containing sunflower oil

Effects of phosphatidylcholine (PC) on the oxidation of oil by singlet oxygen in a W/O microemulsion and an emulsion food model containing tocopherol-stripped sunflower oil (TSSO) have been studied. The W/O microemulsion consisted of methylene chloride, butanol, and sodium dodecyl sulfate with PC (0, 250, 1000 ppm) and TSSO (0, 3.3, 16.5, 33 mg/mL). Production of singlet oxygen in the microemulsion was done chemically with hydrogen peroxide in the presence of sodium molybdate, and indirectly evaluated by rubrene oxidation at A529. The emulsion food model consisted of TSSO, distilled water, and xanthan gum with addition of 250 ppm PC and 4 ppm chlorophyll b, and was placed at 25 degrees C under fluorescent lights (1700 lux) for 24 h. The oxidation of TSSO was determined by thin-layer chromatography and values of conjugated dienoic acid (CDA) and peroxides (POV). PC significantly decreased the oxidation of rubrene and TSSO in the W/O microemulsion, but its content was decreased to approximately one-half by a 20-min reaction, indicating its degradation. This clearly shows that PC acted as an antioxidant via chemical quenching of singlet oxygen in the W/O microemulsion. A possible synergism between PC and TSSO was observed in singlet oxygen quenching in the microemulsion. PC also significantly decreased the chlorophyll-photosensitized oxidation of TSSO in the emulsion food model, possibly by singlet oxygen quenching. This study clearly suggested that PC be used as an antioxidant to improve the lipid oxidative stability of an emulsion food containing chlorophyll under light.

Direct attachment of nanoparticle cargo to Salmonella typhimurium membranes designed for combination bacteriotherapy against tumors

Nanoparticle technology is an emerging approach to resolve difficult-to-manage internal diseases. It is highly regarded, in particular, for medical use in treatment of cancer due to the innate ability of certain nanoparticles to accumulate in the porous environment of tumors and to be toxic to cancer cells. However, the therapeutic success of nanoparticles is limited by the technical difficulty of fully penetrating and thus attacking the tumor. Additionally, while nanoparticles possess seeming-specificity due to the unique physiological properties of tumors themselves, it is difficult to tailor the delivery of nanoparticles or drugs in other models, such as use in cardiac disease, to the specific target. Thus, a need for delivery systems that will accurately and precisely bring nanoparticles carrying drug payloads to their intended sites currently exists. Our solution to this engineering challenge is to load such nanoparticles onto a biological "mailman" (a novel, nontoxic, therapeutic strain of Salmonella typhimurium engineered to preferentially and precisely seek out, penetrate, and hinder prostate cancer cells as the biological delivery system) that will deliver the therapeutics to a target site. In this chapter, we describe two methods that establish proof-of-concept for our cargo loading and delivery system by attaching nanoparticles to the Salmonella membrane. The first method (Subheading 1.1) describes association of sucrose-conjugated gold nanoparticles to the surface of Salmonella bacteria. The second method (Subheading 1.2) biotinylates the native Salmonella membrane to attach streptavidin-conjugated fluorophores as example nanoparticle cargo, with an alternative method (expression of membrane bound biotin target sites using autodisplay plasmid vectors) that increases the concentration of biotin on the membrane surface for streptavidin-conjugated nanoparticle attachment. By directly attaching the fluorophores to our bacterial vector through biocompatible, covalent, and stable bonds, the coupling of bacterial and nanoparticle therapeutic approaches should synergistically lead to improved tumor destruction.

Dopexamine prevents depression of mesenteric blood flow caused by positive end-expiratory pressure in rats

BACKGROUND

The purpose of this study was to investigate the effects of two vasoactive agents, dopamine and dopexamine, on the depression of mesenteric blood flow caused by positive end-expiratory pressure (PEEP) during mechanical ventilation.

METHODS

Sprague-Dawley rats were mechanically ventilated with either no PEEP (control group) or increasing levels of PEEP (PEEP group) up to 20 cm H2O pressure. We evaluated PEEP's effect on blood pressure, cardiac output (CO), and the mesenteric microcirculation with a continuous infusion of 2.5 or 12.5 micrograms/kg/min dopamine or 1, 3, or 5 micrograms/kg/min dopexamine.

RESULTS

PEEP caused a 20% to 25% decrease in mean arterial pressure and a 30% decrease in CO at both 15 and 20 cm H2O of PEEP (all p < 0.05 versus baseline). Low dose dopamine partially corrected the decrease in CO to 16% and 21% below baseline at 15 and 20 cm H2O of PEEP, respectively (both p < 0.05 versus PEEP group) and partially ameliorated the depression of mesenteric blood flow associated with the application of PEEP. High dose dopamine did not positively affect either CO or mesenteric blood flow. Dopexamine had little effect on CO compared with dopamine. All three doses of dopexamine blocked the effect of PEEP on mesenteric blood flow (p < 0.05 compared with the PEEP group at all levels of PEEP, p < 0.05 compared with the low dose dopamine group at 15 and 20 cm H2O of PEEP).

CONCLUSIONS

Dopexamine is superior to dopamine in protecting mesenteric blood flow in the face of increasing levels of PEEP.

Adrenomedullin is inactivated in the lungs of neonatal piglets

Adrenomedullin, a novel 52 amino acid peptide normally present in adult human plasma, has been shown to induce systemic hypotension in the adult rat, pig and cat, and in the new-born piglet. Little is known about the site (s) of adrenomedullin inactivation in adults or neonates. Groups of five 0-2-day old and 2-week old anaesthetized piglets were prepared to enable continuous monitoring of cardiac output, mean systemic arterial pressure, mean pulmonary artery pressure, mean systemic vascular resistance and mean pulmonary vascular resistance. In both age groups, injections of human adrenomedullin1-52 into the left atrium produced significant (P < 0.05) reductions in mean systemic arterial pressure and mean pulmonary artery pressure. Although injections of similar doses of human adrenomedullin1-52 into the right atrium produced significant (P < 0.05) decreases in mean pulmonary artery pressure, there were no appreciable alterations in mean systemic arterial pressure in either age group. These results suggest that the systemic vasodilator properties of human adrenomedullin1-52 are reduced upon first pass through the pulmonary circulation in 2-week old piglets, a phenomenon that is present at birth.

Neither dopamine nor dobutamine corrects mesenteric blood flow depression caused by positive end-expiratory pressure in a rat model of acute lung injury

OBJECTIVE

To determine if either dopamine or dobutamine would counteract the deleterious effect that positive end-expiratory pressure (PEEP) has on cardiac output and mesenteric blood flow in a rat model of acute lung injury.

DESIGN

Prospective, randomized, controlled trial in a clinically relevant model of acute lung injury.

SETTING

Microcirculation research laboratory.

SUBJECTS

Male Sprague-Dawley rats.

INTERVENTIONS

The animals were anesthetized with pentobarbital (30 mg/kg) by intraperitoneal injection. They underwent tracheostomy, jugular and femoral vein cannulation, femoral artery cannulation, carotid artery thermistor placement, and bowel preparation for in vivo video microscopy. Acute lung injury was created by administering 0.1 N hydrochloric acid (1 mL/kg) via the tracheostomy. Dopamine or dobutamine (2.5 or 12.5 microg/kg/min), followed by two intravenous fluid boluses, was administered to rats ventilated with 5, 10, 15, and 20 cm H2O of PEEP.

MEASUREMENTS AND MAIN RESULTS

Mean arterial pressure, thermodilution cardiac output, mesenteric arteriolar diameter, and red blood cell velocity were measured and mesenteric blood flow was calculated. Cardiac output was depressed in rats exposed to 20 cm H2O of PEEP by 32+/-2%. The corresponding values for cardiac output depression at 20 cm H2O of PEEP in rats receiving 2.5 and 12.5 microg/kg/min of dopamine and 2.5 and 12.5 microg/kg/min of dobutamine were 31+/-1%, 21+/-1%, 29+/-0%, and 24+/-2%, respectively. Mesenteric blood flow was depressed in rats ventilated with 20 cm H2O of PEEP by 74+/-3%, while the corresponding values in rats exposed to 20 cm H2O of PEEP and receiving 2.5 or 12.5 microg/kg/min of dopamine or 2.5 or 12.5 microg/kg/min of dobutamine were 86+/-3%, 77+/-3%, 73+/-3%, and 66+/-3%, respectively. Fluid boluses did not correct the deficits in cardiac output or mesenteric blood flow caused by the combination of acute lung injury and PEEP.

CONCLUSIONS

The higher doses of dopamine and dobutamine partially, but insignificantly, corrected the cardiac output depression caused by PEEP in a model of acute lung injury. Neither dose of dopamine nor dobutamine was able to improve PEEP-induced mesenteric blood flow depression.

Comparison of novel synthetic materials with traditional methods to repair exposed abdominal wall fascial defects

Repair of large abdominal wall defects is a challenge, particularly when full-thickness tissue loss prohibits coverage of the fascial repair. Two novel synthetic materials (TMS-1 and TMS-2) have been shown to be better accepted than expanded polytetrafluoroethylene (Gore-Tex), and polypropylene (Marlex) in the closure of clean and contaminated fascial wounds that are immediately covered by skin/soft tissue. Therefore, 1-cm2 abdominal wall defects were created in each of the four quadrants of rat groups. Gore-Tex, Marlex, and TMS-1 or TMS-2 were used to repair three defects, the fourth being primarily closed. To ensure that each repair remained exposed, skin edges were sutured to underlying muscle. Additional animal groups underwent the same protocol; however, peritonitis was induced at surgery using a fecal inoculum technique. Animals were sacrificed 2 weeks later, at which time a blinded observer assessed the surface area and severity of adhesions. In clean wounds, the surface area of formed adhesions was less (p < .004) after primary closure than each synthetic material; among the synthetics, TMS-2 caused significantly (p < .01) less extensive adhesions than Marlex. In addition, the severity of adhesions to TMS-2 was comparable to that of defects closed primarily, and less severe (p < .02) than those formed to Gore-Tex and Marlex. In animals with peritonitis, primary closure caused less extensive (p < .03) adhesions than Marlex and Gore-Tex and significantly (p < .002) less severe adhesions than Marlex, Gore-Tex, and TMS-2. However, the severity of adhesions formed to TMS-1 repairs proved comparable to primarily closed wounds. These experiments reaffirm the tenet that, whenever possible, abdominal wounds should undergo primary fascial closure. When soft tissue coverage over the repair cannot be achieved, TMS-2 is well tolerated in clean wounds. However, the superiority of TMS-1 over the other synthetic materials in contaminated wounds suggests it may also ultimately prove to be of clinical utility.

Neither dopamine nor dobutamine reverses the depression in mesenteric blood flow caused by positive end-expiratory pressure

Positive end-expiratory pressure (PEEP) has been shown to cause a depression of mesenteric blood flow (MBF) and redistribution of blood flow away from the mesenteric vascular bed.

OBJECTIVE

We sought to determine whether two commonly used vasoactive agents, dopamine, a known mesenteric vasodilator and inotrope, and dobutamine, with its inotropic properties, would correct the MBF depression caused by PEEP. DESIGN, MATERIAL, AND METHODS: Sprague-Dawley rats, 180 to 250 g, were treated with mechanical ventilation and either no PEEP (control group) or increasing levels (0, 10, 15, and 20 cm of H2O pressure) of PEEP (PEEP group). Also, we evaluated PEEP's effect on MBF and cardiac output (CO) under the influence of a continuous infusion of 2.5 or 12.5 microgram/kg/min of dopamine or 2.5 or 12.5 microgram/kg/min of dobutamine. Cardiac output and, using in vivo videomicroscopy, mesenteric A1, A2, and A3 arteriolar intraluminal radii and A1 arteriolar optical Doppler velocities were measured. After 20 cm of H2O pressure PEEP was attained, two boluses of 2 mL of 0.9 normal saline were given. The MBF was calculated from vessel radius and red blood cell velocity.

MEASUREMENTS AND MAIN RESULTS

There were no significant changes from baseline in mean arterial pressure or A2 or A3 diameters in any of the groups. Both MBF and CO were unchanged over time in the control group. The MBF was reduced 78% (p < 0.05) and the CO was reduced 31% (p < 0.05) from baseline at 20 cm of H2O pressure PEEP. After 4 mL of normal saline, the MBF was still 53% below baseline (p < 0.05), while the CO had returned to baseline in the PEEP group. Low-dose dopamine partially ameliorated both the decrease in CO and MBF caused by PEEP, but 4 mL of normal saline was required in addition to the low-dose dopamine to return MBF to baseline levels while on 20 cm of H2O pressure PEEP. High-dose dopamine with the addition of 4 mL of normal saline returned CO to baseline on 20 cm of H2O pressure PEEP, but MBF remained approximately 46% below baseline despite fluid boluses. Neither low-dose nor high-dose dobutamine, with or without fluid boluses, had an appreciable positive effect on CO or MBF.

CONCLUSIONS

It is clear that inotropes are not a replacement for adequate fluid loading to correct the depression in cardiac output and mesenteric blood flow associated with the use of mechanical ventilation and PEEP. Low-dose dopamine may serve as an adjunct to adequate fluid resuscitation to improve MBF.

Oxidation of corn oil during frying of soy-flour-added flour dough

Oxidation of corn oil during frying of soy-flour-added dough was studied. Flour dough containing soy flour at 0%, 10%, 20%, and 30% was fried in corn oil at 180 degrees C for 2.5 min, and a total of 60 fryings were performed every 30 min. The oxidation of oil was determined by contents of free fatty acids (FFA), conjugated dienoic acids (CDA), polar compounds, and p-anisidine values (PAV). Tocopherols and phospholipids (PLs) in the oil were determined by HPLC. Tocopherols were present in corn oil at 1000 ppm before frying and increased after the first frying of dough containing soy flour due to tocopherol transfer from soy-flour-added dough to the oil during frying. However, as the oil repeated frying, tocopherol contents decreased and its degradation rate was higher in the oil that fried soy-flour-added dough than in the oil that fried the dough without soy flour. PL was not detected in corn oil before and after frying. As the oil repeated frying, FFA, CDA, and polar compounds contents, and PAV of frying oil increased due to the oil oxidation. The values were higher in the oil which fried soy-flour-added dough than in the oil fried the dough without soy flour, indicating the acceleration of oil oxidation by soy flour added to dough. Increase in the oil oxidation by soy flour added to the dough was highly correlated with fast decomposition of tocopherol in the oil.

Femoral vasodilation to cromakalim is blocked by U37883A, a non-sulphonylurea that selectively inhibits KATP channels

The purpose of the present study was to determine the effects of U37883A, a non-sulphonylurea inhibitor of KATP channels, in the femoral vascular bed of the anaesthetized dog. Administration of U37883A, 4-morpholinecarboxamidine-N-1-adamentyl-N"-cyclohexyl hydrochloride (2.5 mg kg-1, i.v.), significantly inhibited the femoral vasodilator response to intra-femoral arterial injection of cromakalim, an activator of KATP channels. In contrast, U37883A had no effect on the femoral vasodilator responses to nitroglycerin, isoprenaline, 5-HT, or 5-carboxamidotryptamine, suggesting this agent is a novel and selective inhibitor of hindlimb vasodilation induced by KATP-channel activation. Since U37883A did not significantly alter baseline femoral blood flow and femoral vascular resistance, the present data suggest that KATP channels do not contribute, in large measure, to regulating the canine femoral vascular bed under resting conditions in-vivo.

Autonomic control of the regional hemodynamic response to scald

Ultrasonic flow probes were placed around the ascending aorta and each femoral artery of dogs to record cardiac index and femoral blood flow, respectively. Intravenous hexamethonium (n = 5) produced 30% decreases in systemic mean arterial pressure and in cardiac index, and a 14% increase in femoral blood flow, effects that waned over time, consistent with the half-life of the agent. Without hexamethonium, hind paw scalding with boiling water for 5 sec (n = 5) caused a marked increase in ipsilateral femoral artery blood flow (70.7 +/- 8.9 ml/min pre-burn vs 243.7 +/- 23.7 ml/min 5 min post-burn) that persisted for the 3 hr observation period. Contralateral femoral blood flow, systemic mean arterial pressure, and cardiac index were unchanged. Compared to burn only dogs, pre-burn treatment with hexamethonium (n = 6) blunted the femoral vasodilator response to burn (78.8 +/- 9.7 ml/min pre-burn vs 116.5 +/- 7.5 ml/min 5 min post-burn). These data suggest that postganglionic autonomic nerves are at least partially responsible for mediation of the regional vasodilator response to thermal injury.

Effect of peritoneal and gastric irrigation with ozonated saline on arterial and venous blood gas values

Ozone, a proven in vitro antiseptic agent, has been shown in vivo to reduce infectious morbidity when used as a lavage solution in rodent fecal peritonitis. As concern that absorption of hydroxyl radical byproducts of ozone breakdown might be deleterious to blood buffering capacity, the effects of a 5 minute intragastric or peritoneal lavage with ozonated saline on rodent arterial and venous blood gas values were determined. Compared to values obtained following lavage with oxygenated saline or normal saline, ozonated saline irrigation produced no appreciable alterations in arterial or venous pH, pO2, and pCO2 over a 1 hour observation period. Short-term ozonated saline peritoneal lavage does not appreciably effect rodent blood buffering capacity.