Outpatient intravenous diuresis in a rural setting: safety, efficacy, and outcomes.

Purpose: To evaluate the safety, efficacy, and outcomes of outpatient intravenous diuresis in a rural setting and compare it to urban outcomes. Methods: A single-center study was conducted on 60 patients (131 visits) at the Dartmouth-Hitchcock Medical Center (DHMC) from 1/2021-12/2022. Demographics, visit data, and outcomes were collected and compared to urban outpatient IV centers, and inpatient HF hospitalizations from DHMC FY21 and national means. Descriptive statistics, T-tests and chi-squares were used. Results: The mean age was 70 ± 13 years, 58% were male, and 83% were NYHA III-IV. Post-diuresis, 5% had mild-moderate hypokalemia, 16% had mild worsening of renal function, and 3% had severe worsening of renal function. No hospitalizations occurred due to adverse events. The mean infusion-visit urine output was 761 ± 521 ml, and post-visit weight loss was -3.9 ± 5.0 kg. No significant differences were observed between HFpEF and HFrEF groups. 30-day readmissions were similar to urban outpatient IV centers, DHMC FY21, and the national mean (23.3% vs. 23.5% vs. 22.2% vs. 22.6%, respectively; p = 0.949). 30-day mortality was similar to urban outpatient IV centers but lower than DHMC FY21 and the national means (1.7% vs. 2.5% vs. 12.3% vs. 10.7%, respectively; p < 0.001). At 60 days, 42% of patients had ≥1 clinic revisit, 41% had ≥1 infusion revisit, 33% were readmitted to the hospital, and two deaths occurred. The clinic avoided 21 hospitalizations, resulting in estimated cost savings of $426,111. Conclusion: OP IV diuresis appears safe and effective for rural HF patients, potentially decreasing mortality rates and healthcare expenses while mitigating rural-urban disparities.

A highly predictive cardiac positron emission tomography (PET) risk score for 90-day and one-year major adverse cardiac events and revascularization.

BACKGROUND: With the increase in cardiac PET/CT availability and utilization, the development of a PET/CT-based major adverse cardiovascular events, including death, myocardial infarction (MI), and revascularization (MACE-Revasc) risk assessment score is needed. Here we develop a highly predictive PET/CT-based risk score for 90-day and one-year MACE-Revasc. METHODS AND RESULTS: 11,552 patients had a PET/CT from 2015 to 2017 and were studied for the training and development set. PET/CT from 2018 was used to validate the derived scores (n = 5049). Patients were on average 65 years old, half were male, and a quarter had a prior MI or revascularization. Baseline characteristics and PET/CT results were used to derive the MACE-Revasc risk models, resulting in models with 5 and 8 weighted factors. The PET/CT 90-day MACE-Revasc risk score trended toward outperforming ischemic burden alone [P = .07 with an area under the curve (AUC) 0.85 vs 0.83]. The PET/CT one-year MACE-Revasc score was better than the use of ischemic burden alone (P < .0001, AUC 0.80 vs 0.76). Both PET/CT MACE-Revasc risk scores outperformed risk prediction by cardiologists. CONCLUSION: The derived PET/CT 90-day and one-year MACE-Revasc risk scores were highly predictive and outperformed ischemic burden and cardiologist assessment. These scores are easy to calculate, lending to straightforward clinical implementation and should be further tested for clinical usefulness.

Spectrum of radionuclide perfusion study abnormalities in takotsubo cardiomyopathy.

BACKGROUND: Takotsubo (stress) cardiomyopathy (TCM) is characterized by transient apical left ventricular dysfunction precipitated by emotional or physical stress. Its presentation makes it difficult to differentiate from an acute coronary syndrome. A suggestive echocardiogram plus normal coronary angiography most often are used for diagnosis. Radionuclide perfusion study (RPS) findings in TCM, including by positron emission tomography (PET), have been poorly characterized. METHODS AND RESULTS: Intermountain Healthcare electronic medical records were searched from 2009 to 2019 for patients with a discharge diagnosis of TCM, stress CM, or takotsubo syndrome. 16 TCM patients with an RPS, including by PET in 8, were identified: 13 (81%) were women; age averaged 72 years (50-89 years); 14 had an identified stressor. TCM diagnosis was definite in 11 and probable/possible in 5. RPS was abnormal in 11, with 9 showing an apical perfusion deficit, whereas angiography in 14 showed normal coronaries in 12 and non-obstructive disease in 2. Echo ejection fraction averaged 41% (29%-60%); an apical wall motion abnormality was present in 14 (88%). Troponin elevations were noted in 14/15. The presenting ECG was abnormal is 14, frequently showing ST-T-wave abnormalities. 13 patients were discharged on a beta-blocker. Follow-up echo (in 12) showed recovered ejection fraction in 9 and recovered apical wall motion in 11. CONCLUSIONS: Despite having normal or non-obstructive epicardial coronary arteries on angiography, TCM patients frequently present with apical wall motion abnormalities and matching RPS perfusion defects. These findings suggest microvascular abnormalities, whose pathophysiology, temporal course, and clinical implications should be the subject of further investigation.

Coronary Artery Calcium Versus Pooled Cohort Equations Score for Primary Prevention Guidance: Randomized Feasibility Trial.

OBJECTIVES: This study sought to determine the feasibility of performing an extensive randomized outcomes trial comparing a coronary artery calcium (CAC)- versus a pooled cohort equations (PCE) risk score-based strategy for initiating statin therapy for primary atherosclerotic cardiovascular disease (ASCVD) prevention. BACKGROUND: Statin therapy is standard for the primary prevention of ASCVD in subjects at increased risk. National guidelines recommend using the American College of Cardiology/American Heart Association PCE risk score to guide a statin recommendation. Whether guidance by a CAC score is equivalent or superior is unknown. METHODS: CorCal (Effectiveness of a Proactive Cardiovascular Primary Prevention Strategy, With or Without the Use of Coronary Calcium Screening, in Preventing Future Major Adverse Cardiac Events) was a randomized trial consenting 601 patients without known ASCVD, diabetes, or prior statin therapy recruited from primary care clinics and randomized to CAC- (n = 302) or PCE guidance (n = 299) of statin initiation for primary prevention. Enrolled subjects and their physicians made final treatment decisions. Primary outcomes compared the proportion of statin recommendations received and subject adherence over 1 year between CAC- and PCE-arm subjects. Modeled medical costs, adverse effects, and low-density lipoprotein-cholesterol (LDL-C) were additional measures of interest. RESULTS: Subjects were well matched, and 540 (89.9%) completed entry testing and received a protocol-based recommendation. A statin was recommended in 101 (35.9%) CAC-arm and 124 (47.9%) PCE-arm subjects (P = 0.005). Compared to PCE-based recommendations, CAC-arm subjects were reclassified from statin to no statin in 36.0% and from no statin to statin in 5.6% of cases, resulting in a total reclassification of 20.6%. Physicians accepted the study-dictated recommendation to start a statin in 88.1% of CAC-arm vs 75.0% of PCE-arm subjects (P = 0.01). Patient-reported adherence to this recommendation at 3 months was 62.2% vs 42.2%, respectively (P = 0.009). At 1 year, statin adherence remained superior, LDL-C levels were lower, estimated costs were similar or reduced in CAC subjects, and few events occurred. CONCLUSIONS: CAC guidance may be a more efficient, personalized, cost-effective, and motivating approach to statin initiation and maintenance in primary prevention. This feasibility phase of CorCal should be regarded as hypothesis-generating with respect to cardiovascular outcomes, which is being addressed in a large, longer-term outcomes trial. (Effectiveness of a Proactive Cardiovascular Primary Prevention Strategy, With or Without the Use of Coronary Calcium Screening, in Preventing Future Major Adverse Cardiac Events [CorCal]; NCT03439267).

Absent or Mild Coronary Calcium Predicts Low-Risk Stress Test Results and Outcomes in Patients Considered for Flecainide Therapy.

BACKGROUND: Flecainide is a useful antiarrhythmic for atrial fibrillation (AF). However, because of ventricular proarrhythmia risk, a history of myocardial infarction (MI) or coronary artery disease (CAD) is a flecainide exclusion, and stress testing is used to exclude ischemia. We assessed whether absent/mild coronary artery calcium (CAC) can supplement or avoid the need for stress testing. METHODS: We assessed ischemic burden using regadenoson Rb-82 PET/CT in 1372 AF patients ≥50 years old without symptoms or signs of clinical CAD. CAC was determined qualitatively by low dose attenuation computed tomography (CT) (n = 816) or by quantitative CT (n = 556). Ischemic burden and clinical outcomes were compared by CAC burden. RESULTS: Patients with CAC absent or mild (n = 766, 57.2%) were younger, more frequently female, and had higher BMI but lower rates of diabetes, hypertension, and dyslipidemia. Average ischemic burden was lower in CAC-absent/mild patients, and CAC-absent/mild patients showed greater coronary flow reserve, had fewer referrals for coronary angiography, and less often had obstructive CAD. Revascularization at 90 days was lower, and the rate of longer-term major adverse cardiovascular events was favorable. CONCLUSIONS: An easily administered, inexpensive, low radiation CAC scan can identify a subset of flecainide candidates with a low ischemic burden on PET stress testing that rarely needs coronary angiography/intervention and has favorable outcomes. Absent or mild CAC-burden combined with other clinical information may avoid or complement routine stress testing. However, additional, ideally randomized and multicenter trials are indicated to confirm these findings before replacing stress testing with CAC screening in selecting patients for flecainide therapy in clinical practice.

Absence of Coronary Artery Calcium During Positron Emission Tomography Stress Testing in Patients Without Known Coronary Artery Disease Identifies Individuals With Very Low Risk of Cardiac Events.

BACKGROUND: Myocardial perfusion imaging, including positron emission tomography/computed tomography (PET/CT), is often used to assess for high-grade coronary artery disease (CAD) requiring revascularization. The use of coronary artery calcium (CAC) to predict risk of major adverse cardiovascular events in asymptomatic patients is accepted. However, little is known regarding the use of CAC in PET/CT patients without known CAD in identifying patients unlikely to need revascularization. Here, we determined whether the absence of CAC, using low-dose attenuation correction CT obtained during the PET/CT, identifies patients unlikely to undergo coronary revascularization within 90 days of a PET/CT. METHODS: Patients, without a history of CAD and no elevation in troponin, referred for PET/CT at Intermountain Medical Center were studied (n=5528). The presence of CAC was visually assessed using low-dose attenuation correction CT. The association between CAC and 90-day high-grade CAD and revascularization were assessed. Longer-term (up to 4 years) major adverse cardiovascular events, including all-cause death, myocardial infarction, and late revascularization (>90 days), were examined. RESULTS: There were 2510 (45.4%) patients in CAC-present group and 3018 (54.6%) patients in CAC-absent group. The CAC-absent group, compared with the CAC-present group, was less likely to undergo coronary angiography (3.4% versus 10.2%, P<0.0001), have high-grade CAD (0.5% versus 6.5%, P<0.0001), and receive revascularization (0.4% versus 5.8%, [adjusted odds ratio =0.09; 95% CI, 0.05-0.16]; P<0.0001). In patients with an ischemic burden >10%, the CAC-absent group was associated with reduced revascularization (P<0.0001). Longer-term major adverse cardiovascular events were lower in the CAC-absent (2.4%) compared with the CAC-present (6.9%) group (adjusted hazard ratio, 0.45 [95% CI, 0.34-0.60]; P<0.0001). CONCLUSIONS: The absence of CAC on low-dose attenuation correction CT identifies PET/CT patients unlikely to have high-grade CAD or require revascularization within 90 days and unlikely to experience longer-term major adverse cardiovascular events. The prognostic value of CAC, beyond ischemic burden, suggests its potential as a first-step screening tool in intermediate-risk patients to identify those who do not need coronary revascularization.

Comparison of Three Atherosclerotic Cardiovascular Disease Risk Scores With and Without Coronary Calcium for Predicting Revascularization and Major Adverse Coronary Events in Symptomatic Patients Undergoing Positron Emission Tomography-Stress Testing.

Atherosclerotic cardiovascular disease (ASCVD) is the most important cause of morbidity and mortality nationally and internationally. Improving ASCVD risk prediction is a high clinical priority. We sought to determine which of 3 ASCVD risk scores best predicts the need for revascularization and incident major adverse coronary events (MACE) in symptomatic patients at low-to-intermediate primary ASCVD risk referred for regadenoson-stress positron emission tomography (PET). Risk scores included the standard ASCVD pooled cohort equation (PCE), the multiethnic study of atherosclerosis (MESA) risk equation, and the coronary artery calcium score (CACS), obtained by PET. All qualifying patients in our institution at primary ASCVD risk referred for PET-stress tests in whom PCE, MESA, and CAC scores could be calculated were studied. CACS categories were: 0, 1 to 10, 11 to 299, 300 to 999, and 1000+. MESA and PCE scores were divided into quartiles. Logistic regression modeling was used to predict clinical/PET-driven early revascularization (within 90 days) and 1-year MACE (death, myocardial infarction, or any-time revascularization). A total of 981 patients (54% men, age 67 ± 10 years) qualified and were studied. Scores including CAC (MESA, CACS) performed better than PCE for predicting overall 1-year MACE (MESA p <0.001, CACS p = 0.012 vs PCE), which was driven by early revascularization. In conclusion, in a large population of patients at primary ASCVD risk referred for PET-stress testing, risk scores including CAC (CACS, MESA), which better predicted early revascularization and 1-year MACE, may be particularly useful in primary coronary risk assessment when considering whom to refer for PET-stress testing.

Implementation of a cardiac PET stress program: comparison of outcomes to the preceding SPECT era.

BACKGROUND: Cardiac positron emission testing (PET) is more accurate than single photon emission computed tomography (SPECT) at identifying coronary artery disease (CAD); however, the 2 modalities have not been thoroughly compared in a real-world setting. We conducted a retrospective analysis of 60-day catheterization outcomes and 1-year major adverse cardiovascular events (MACE) after the transition from a SPECT- to a PET-based myocardial perfusion imaging (MPI) program. METHODS: MPI patients at Intermountain Medical Center from January 2011-December 2012 (the SPECT era, n = 6,777) and January 2014-December 2015 (the PET era, n = 7,817) were studied. Outcomes studied were 60-day coronary angiography, high-grade obstructive CAD, left main/severe 3-vessel disease, revascularization, and 1-year MACE-revascularization (MACE-revasc; death, myocardial infarction [MI], or revascularization >60 days). RESULTS: Patients were 64 ± 13 years old; 54% were male and 90% were of European descent; and 57% represented a screening population (no prior MI, revascularization, or CAD). During the PET era, compared with the SPECT era, a higher percentage of patients underwent coronary angiography (13.2% vs. 9.7%, P < 0.0001), had high-grade obstructive CAD (10.5% vs. 6.9%, P < 0.0001), had left main or severe 3-vessel disease (3.0% vs. 2.3%, P = 0.012), and had coronary revascularization (56.7% vs. 47.1%, P = 0.0001). Similar catheterization outcomes were seen when restricted to the screening population. There was no difference in 1-year MACE-revasc (PET [5.8%] vs. SPECT [5.3%], P = 0.31). CONCLUSIONS: The PET-based MPI program resulted in improved identification of patients with high-grade obstructive CAD, as well as a larger percentage of revascularization, thus resulting in fewer patients undergoing coronary angiography without revascularization. FUNDING: This observational study was funded using internal departmental funds.

Effect of riboflavin on the photo-oxidative stability of vegetable oil in salad dressing.

Differential scanning calorimetry (DSC), headspace oxygen and solid phase microextraction gas chromatography and peroxide value were used to evaluate the effect of riboflavin on the photo-oxidation of vegetable oil in salad dressing. Salad dressings with 0, 5, 20, 50 and 100 ppm added riboflavin were stored under light (2500 lux) at 25 °C for 5 days. Crystallisation peaks in the DSC thermograms of the oil samples shifted to lower temperatures and enthalpies decreased as the storage time increased. As the riboflavin concentrations increased from 0 to 100 ppm, the crystallisation enthalpies increased from 27 to 31 J/g and the maximum crystallisation temperature increased from -64 to -62 °C during the 5 day storage. Headspace oxygen depletion rates, the formation of volatile compounds and peroxide values of the salad dressing samples simultaneously decreased with the addition of riboflavin, showing that riboflavin protected the oil in salad dressing from photo-oxidation.

Luminescence spectroscopic observation of singlet oxygen formation in extra virgin olive oil as affected by irradiation light wavelengths, 1,4-diazabicyclo[2.2.2]octane, irradiation time, and oxygen bubbling.

A spectrofluorometer equipped with a highly sensitive near-IR InGaAs detector was used for the direct visualization of singlet oxygen emission at 1268 nm in olive oil during light irradiation with various different wavelengths. The virgin olive oil in methylene chloride (20% w/v, oxygen saturated) was irradiated at the 301, 417, 454, 483, and 668 nm, then the emission at 1268 nm, singlet oxygen dimole decaying was observed. The result showed the highest production of (1)O(2) with light irradiation at 417 nm, and followed by at 668 nm in virgin olive oil, indicating that pheophytin a and chlorophyll a were the most responsible components for the production of singlet oxygen. The UV light irradiations at the wavelength of 200, 250, and 300 nm did not induce any detectable luminescence emission at 1268 nm, but 350 nm produced weak emission at 1269 nm. The quantity of (1)O(2) produced with excitation at 350 nm was about 1/6 of that of irradiation at 417 nm. Addition of an efficient (1)O(2) quencher, 1,4-diazabicyclo[2.2.2]octane, in virgin olive oil in methylene chloride greatly decreased the luminescence emission at 1268 nm, confirming the singlet oxygen production in olive oil. Singlet oxygen production was more efficient in oxygen-purged virgin olive oil than in oxygen non-purged olive oil. This represents first report on the direct observation of singlet oxygen formation in olive oil as well as in real-food system after visible light illumination. Practical Application: The present results show the positive evidence of the singlet oxygen involvement in rapid oxidative deterioration of virgin olive oil under visible light. This paper also shows the effects of different wavelength of light irradiation on the formation of singlet oxygen in olive oil. The present results would provide important information for the understanding of the mechanism involved in rapid oxidative quality deterioration of virgin olive oil under light illumination and for searching the preventive methods of deterioration of olive oil quality under light.

Differential inhibitory effects of conjugated linoleic acid isomers on mouse forestomach neoplasia induced by benzo(a)pyrene.

The differential anticarcinogenic activity of conjugated linoleic acid (CLA) isomers, including c9,t11-CLA, t10,c12-CLA, and t,t-CLA, was examined in a mouse forestomach carcinogenesis regimen induced by benzo(a)pyrene (BP). Female ICR mice (6-7 weeks of age, 26 +/- 1 g) were divided into six groups (30 mice/group, 5 mice/cage): control, linoleic acid, CLA, c9,t11-CLA, t10,c12-CLA, and t,t-CLA. Each mouse was orally given 0.1 mL of sample and 0.1 mL of olive oil on Monday and Wednesday and BP (2 mg in 0.2 mL of olive oil) on Friday. This cycle was repeated four times. Twenty-three weeks later, the experiment was terminated for tumor analysis. t,t-CLA significantly reduced (p < 0.05) both tumor number and tumor size per mouse, relative to CLA and c9,t11-CLA, but similar to t10,c12-CLA. Reduction in tumor incidence by t,t-CLA (84.6%) was similar to that by CLA, c9,t11-CLA, and t10,c12-CLA, but it was significantly reduced (p < 0.05), relative to 100% linoleic acid and control. t,t-CLA elevated the apoptotic index to 35%, relative to 23% for CLA, 21% for c9,t11-CLA, 29% for t10,c12-CLA, 7% for linoleic acid, and 4% for control. t,t-CLA up-regulated the expression of the Bax gene and activated caspase-3 enzymes but down-regulated expression of the Bcl-2 gene. Cytosolic phospholipase A(2) activity was not affected by the CLA isomers tested. These results suggest that t,t-CLA has superior anticarcinogenic potential on BP-induced mouse forestomach neoplasia to CLA, c9,t11-CLA, and t10,c12-CLA, via the induction of apoptosis through mitochondrial dysfunction.

Prooxidant activity of oxidized alpha-tocopherol in vegetable oils.

The effect of oxidized alpha-tocopherol on the oxidative stabilities of soybean, corn, safflower, and olive oils and the oxidation of oleic, linoleic, and linolenic acids were studied. The 0, 650, 1300, and 2600 ppm oxidized alpha-tocopherol were added to soybean, corn, safflower, and olive oils and 10000 ppm oxidized alpha-tocopherol to the mixture of oleic, linoleic, and linolenic acids. Samples in the gas-tight vials were stored in the dark for 6 or 35 d at 55 degrees C. The oxidative stabilities of oils were determined by headspace oxygen with GC and peroxide value. Fatty acids were determined by GC. As the concentration of oxidized alpha-tocopherol in soybean, corn, safflower, and olive oils increased, the depletion of headspace oxygen and the peroxide values of oils increased during storage. The prooxidant effects of oxidized alpha-tocopherol on soybean and corn oils with about 55% linoleic acid were greater than those on safflower and olive oils with about 12% linoleic acid, respectively (P < 0.05). The changes of fatty acids during storage showed that the oxidation ratios of oleic, linoleic, and linolenic acids were 1 : 2 : 3, 1 : 12 : 26, and 1 : 8 : 16 after 5, 30, and 35 d of storage, respectively. The oxidation of alpha-tocopherol in oil should be prevented and the oxidized alpha-tocopherol should be removed to improve the oxidative stability of oils.

ESR study of the singlet oxygen quenching and protective activity of Trolox on the photodecomposition of riboflavin and lumiflavin in aqueous buffer solutions.

Singlet oxygen quenching activity of Trolox, a water-soluble derivative of tocopherol, was studied by electron spin resonance (ESR) spectroscopy in a buffer solution (pH 7.4) containing methylene blue (MB), 2,2,6,6-tetramethyl-4-piperidone (TMPD) after light illumination for 30 min. Trolox at the concentration of 125 microM quenched 89.1% singlet oxygen in the system. Trolox showed significantly higher singlet oxygen quenching activity than ascorbic acid in the buffer solution (P < 0.05). Riboflavin in phosphate buffer solutions was degraded very fast under fluorescent light illumination. The photodegradation rate of riboflavin at pH 8.5 was significantly higher than pHs 4.5 and 6.5 (P < 0.05). Lumiflavin was also degraded under the fluorescent light illumination, but its degradation rate was much lower than that of riboflavin under the same light intensity. Unlike riboflavin, the rate of lumiflavin photodegradation was the greatest at pH 4.5 and followed by pHs 6.5 and 8.5, in a decreasing order. Trolox greatly protected the photodegradation of riboflavin and lumiflavin. The protective activities of Trolox against the photodegradation of riboflavin and lumiflavin were also pH dependent. The treatments of 5 mM Trolox in the buffer solutions of pHs 8.5 and 6.5 exhibited 56.1% and 31.7% protection of riboflavin against degradation during 120 min light illumination, respectively. The treatments of Trolox at the concentrations of 1, 3, and 5 mM in the buffer of 6.5 exhibited 14.8%, 58.4%, and 81.4% protection of lumiflavin against degradation during 24 h light illumination, respectively.

Quenching mechanism and kinetics of ascorbic acid on the photosensitizing effects of synthetic food colorant FD&C Red Nr 3.

The pH effect on the oxidative stability of ascorbic acid in the presence of food colorant FD&C Red Nr 3 during storage with or without light was investigated. The quenching mechanism and kinetics of ascorbic acid on the FD&C Red Nr 3 photosensitized oxidation in an aqueous system at 25 degrees C were also studied by measuring the degradation of ascorbic acid or depletion of headspace oxygen. Red Nr 3 had no influence on the oxidation of ascorbic acid under dark storage, but accelerated its oxidation rate under light storage. The oxidative stability of ascorbic acid decreased as the pH increased from 4 to 7 under light without FD&C Red Nr 3. The quenching rates of ascorbic acid on the singlet oxygen by measuring the degradation of ascorbic acid in the presence of Red Nr 3 under light storage were 1.53 +/- 0.15 x 10(8), 1.86 +/- 0.25 x 10(8), and 1.19 +/- 0.12 x 10(8) M(-1)S(-1) at pH 4, 5.6, and 7, respectively.

Quenching mechanisms and kinetics of Trolox and ascorbic acid on the riboflavin-photosensitized oxidation of tryptophan and tyrosine.

The effects of 0, 0.3, 0.6, and 0.9 mM Trolox and ascorbic acid on the singlet oxygen oxidation of tryptophan and tyrosine containing 25 ppm of riboflavin were determined by measuring tryptophan and tyrosine concentration by high-performance liquid chromatography analysis. The samples were stored in the a 1000 lx light storage box for 4 h at 30 degrees C. As the concentration of Trolox and ascorbic acid increased, the degradation of tryptophan and tyrosine decreased significantly at p < 0.05. Trolox reduced tryptophan and tyrosine degradation by quenching both singlet oxygen and excited triplet riboflavin, whereas ascorbic acid quenched singlet oxygen only. The total singlet oxygen quenchings of Trolox in the presence of tryptophan and tyrosine were 1.55 x 10(7) and 1.32 x 10(7) M(-1) s(-1), respectively. The total singlet oxygen quenchings of ascorbic acid in the presence of tryptophan and tyrosine were 1.16 x 10(7) and 1.10 x 10(7) M(-1) s(-1), respectively. Trolox was more effective than ascorbic acid in preventing the degradation of tryptophan and tyrosine.

Photoinduced generation of 2,3-butanedione from riboflavin.

The volatile compound formation from riboflavin solution of a phosphate buffer (0.1 M, pH 6.5) under light for 15 h was studied by SPME-GC and SPME-GC/MS analysis. Only one major compound in the riboflavin solution was formed and increased as the light exposure time increased. The light-exposed riboflavin solution had a buttery odor. The compound of riboflavin solution under light was analyzed by gas chromatography and olfactometry. The major volatile compound eluted from the gas chromatograph had a buttery odor. The buttery odor compound was positively identified as 2,3-butanedione by a combination of gas chromatographic retention time, mass spectrum, and odor evaluation of authentic 2,3-butanedione. The addition of sodium azide, a singlet oxygen quencher, to riboflavin solution minimized the formation of the buttery odor compound. Singlet oxygen was involved in the formation of the buttery odor. The 2,3-butanedione was produced from the reaction between riboflavin and singlet oxygen. Singlet oxygen was formed from triplet oxygen by riboflavin photosensitization mechanism. This is the first reported oxidation reaction between riboflavin and singlet or triplet in food and biological systems.

Production of silkworms with conjugated linoleic acid (CLA) incorporated into their lipids by dietary CLA.

Silkworms with conjugated linoleic acid (CLA) incorporated into their lipids (designated CLA silkworms) were produced to enhance the quality of silkworms having a synergistic effect with CLA functions by dietary synthetic CLA. Silkworm larvae were fed fresh mulberry leaves (control diet) until the third instar stage and were then subjected to various levels (0%, 0.1%, 1%, 5%, and 10%) of CLA-sprayed mulberry leaves (designated CLA diet) beginning on the first day of the fourth instar stage and continuing to the third day of the fifth instar stage. CLA contents in CLA silkworms increased proportionally with increasing CLA levels of CLA diets. CLA silkworms on a 1% CLA diet contained 2.2 g CLA/100 g lipid without body weight reduction, whereas CLA silkworms on a 10% CLA diet contained 14.8 g CLA/100 g lipid with a significant reduction of body weight, relative to the control silkworms. The CLA content in the lipids of CLA silkworms on a 10% CLA diet was significantly higher than that of CLA silkworms on a 5% CLA diet. A 0.1% CLA diet was not sufficient to accumulate CLA in the silkworms. Most of the CLA (approximately 99%) of silkworm lipids was present in triglyceride (TG) with a similar ratio of c9,t11 and t10,c12 CLA isomers. These results suggest that a 1% CLA diet was suitable for the production of CLA silkworms.

Hydrogenation and interesterification effects on the oxidative stability and melting point of soybean oil.

Soybean oil with an iodine value of 136 was hydrogenated to have iodine values of 126 and 117. The soybean oils with iodine values of 136, 126, and 117 were randomly interesterified using sodium methoxide. The oxidative stabilities of the hydrogenated and/or interesterified soybean oils were evaluated by measuring the headspace oxygen content by gas chromatography, and the induction time was measured using Rancimat. The melting points of the oils were evaluated by differential scanning calorimetry. Duncan's multiple range test of the headspace oxygen and induction time showed that hydrogenation increased the headspace oxygen content and induction time at alpha = 0.05. Interesterification decreased the headspace oxygen and the induction time for the soybean oils with iodine values of 136, 126, and 117 at alpha = 0.05. Hydrogenation increased the melting points as the iodine value decreased from 136 and 126 to 117 at alpha = 0.05. The random interesterification increased the melting points of soybean oils with iodine values of 136, 126, and 117 at alpha = 0.05. The combined effects of hydrogenation and interesterification increased the oxidative stability of soybean oil at alpha = 0.05 and the melting point at alpha = 0.01. The optimum combination of hydrogenation and random interesterification can improve the oxidative stability and increase the melting point to expand the application of soybean oil in foods.

Effects, quenching mechanisms, and kinetics of water soluble compounds in riboflavin photosensitized oxidation of milk.

To protect the nutrient and flavor stability of milk under light, the effects of 0, 0.01, 0.03, and 0.05 M 1,4-diazabicyclo[2,2,2]octane (DABCO) and 2,5-dimethylfuran (DMF) on the riboflavin photosensitized oxidation of milk were studied. The oxidation of milk was studied by measuring the headspace oxygen in sample bottles after 3 h of light exposure at 3000 lux. As the concentration of DABCO and DMF, which are water soluble compounds, increased in the sample from 0, 0.01, and 0.03 to 0.05 M, the depleted headspace oxygen content significantly decreased (P < 0.05). Steady state kinetic studies of singlet oxygen oxidation showed that the antioxidant activity of DABCO and DMF was due to singlet oxygen quenching. The reaction rate constant of singlet oxygen with milk fat was 8.1 x 10(5) M(-1) s(-1). Total singlet oxygen quenching rates of DABCO and DMF were 1.5 x 10(7) and 2.6 x 10(7) M(-1) s(-1), respectively. DABCO and DMF could be used to slow the reaction between singlet oxygen and milk components to protect nutrients, especially riboflavin, and to improve the oxidative stability of milk fat during storage or processing under light.

Photosensitizing effect of riboflavin, lumiflavin, and lumichrome on the generation of volatiles in soy milk.

Lumichrome and lumiflavin were formed from riboflavin under light. pH had a significant influence on the formation of lumichrome and lumiflavin from riboflavin. Lumichrome was the only major product from riboflavin under neutral or acidic pH values. Lumiflavin was also formed from riboflavin in basic pH. The maximum concentration of lumiflavin from 100 microM riboflavin at pH 8.5 was 30.9 microM, and it was reached after 2 h of exposure at 1500 lux. The maximum concentration of lumichrome formed from 100 microM riboflavin at pH 4.5, 6.5, or 8.5 was 79.9, 58.7, and 73.1 microM, respectively, after 8, 6, or 2 h of light exposure. The formation of lumichrome and lumiflavin from riboflavin was due to the type I mechanism of the riboflavin photosensitized reaction. Singlet oxygen was also involved in the photosensitized degradation of lumiflavin and lumichrome. The reaction rates of riboflavin, lumiflavin, and lumichrome with singlet oxygen were 9.66 x 10(8), 8.58 x 10(8), and 8.21 x 10(8) M(-1) s(-1), respectively. The headspace oxygen depletion and headspace volatile formation were significant in soy milk containing lumichrome or lumiflavin under light (p < 0.05) and were insignificant (p > 0.05) in the dark. Ascorbic acid could inhibit the total volatile changes of soy milk under light. Soy milk should be protected from light to prevent the photodegradation of riboflavin and the oxidation of soy milk.