Plasma Ascorbate Concentrations Research Articles

Effects of Green and Gold Kiwifruit Varieties on Antioxidant Neuroprotective Potential in Pigs as a Model for Human Adults.

Kiwifruit (KF) has shown neuroprotective potential in cell-based and rodent models by augmenting the capacity of endogenous antioxidant systems. This study aimed to determine whether KF consumption modulates the antioxidant capacity of plasma and brain tissue in growing pigs. Eighteen male pigs were divided equally into three groups: (1) bread, (2) bread + Actinidia deliciosa cv. 'Hayward' (green-fleshed), and (3) bread + A. chinensis cv. 'Hort16A' (yellow-fleshed). Following consumption of the diets for eight days, plasma and brain tissue (brain stem, corpus striatum, hippocampus, and prefrontal cortex) were collected and measured for biomarkers of antioxidant capacity, enzyme activity, and protein expression assessments. Green KF significantly increased ferric-reducing antioxidant potential (FRAP) in plasma and all brain regions compared with the bread-only diet. Gold KF increased plasma ascorbate concentration and trended towards reducing acetylcholinesterase activity in the brain compared with the bread-only diet. Pearson correlation analysis revealed a significant positive correlation between FRAP in the brain stem, prefrontal cortex, and hippocampus with the total polyphenol concentration of dietary interventions. These findings provide exploratory evidence for the benefits of KF constituents in augmenting the brain's antioxidant capacity that may support neurological homeostasis during oxidative stress.

Cerebrospinal fluid and plasma ascorbate concentrations following subarachnoid haemorrhage

BackgroundAscorbate, the biologically active form of vitamin C, is the primary neural anti-oxidant. Ascorbate concentrations have never been quantified following aneurysmal subarachnoid haemorrhage (aSAH). ObjectiveTo quantify plasma and cerebrospinal fluid (CSF) ascorbate concentrations in patients following SAH. Design, Setting, Participants, Main Outcome MeasuresCohort study in which plasma and CSF ascorbate concentrations were measured longitudinally in 12 aSAH patients admitted to a quaternary referral intensive care unit and compared to one-off samples obtained from 20 pregnant women prior to delivery in a co-located obstetric hospital. Data are median [interquartile range] or median (95 % confidence intervals). ResultsForty-eight plasma samples were obtained from the 12 aSAH patients (eight females, age 62 [53–68] years). Eight participants with extra-ventricular drains provided 31 paired CSF-plasma samples. Single plasma and CSF samples were obtained from 20 pregnant women (age 35 [31–37] years). Initial plasma and CSF ascorbate concentrations post aSAH were less than half those in pregnant controls (plasma: aSAH: 31 [25–39] μmol/L vs. comparator: 64 [59–77] μmol/L; P < 0.001 and CSF: 116 [80–142] μmol/L vs. 252 [240–288] μmol/L; P < 0.001). Post aSAH there was a gradual reduction in the CSF:plasma ascorbate ratio from ∼4:1 to ∼1:1. Six (50 %) patients developed vasospasm and CSF ascorbate concentrations were lower in these patients (vasospasm: 61 (25, 97) vs. no vasospasm: 110 (96, 125) μmol/L; P = 0.01). ConclusionPost aSAH there is a marked reduction in CSF ascorbate concentration that is most prominent in those who develop vasospasm.

β-Carotene Supplementation Increases Antioxidant Capacity of Plasma in Older Women , ,

The antioxidant effect of dietary beta-carotene supplementation on the peroxidation potential of plasma was investigated in a randomized double-blind, placebo-controlled study. Twelve healthy women (62-80 y) supplemented their usual daily diet with 90 mg of beta-carotene (n = 6) or placebo (n = 6) capsules for 3 wk. Plasma concentrations of beta-carotene, alpha- and gamma-tocopherol, ascorbate, urate, bilirubin and in vitro production of phosphatidylcholine hydroperoxides (PC-OOH) and utilization of plasma antioxidants in the presence of 50 mmol/L 2,2'-azobis (2-aminopropane) hydrochloride (AAPH), a free radical generator, at 37 degrees C were measured before and after dietary treatment. Plasma beta-carotene increased from 0.76 +/- 0.16 to 6.45 +/- 1.16 micromol/L (P < 0.05) in supplemented but not placebo-treated subjects. The plasma concentrations of other antioxidants did not change significantly in either group. beta-Carotene supplementation did not affect basal levels of plasma PC-OOH as measured by HPLC post-column chemiluminescence but did affect AAPH-induced production of PC-OOH. Before supplementation, the induction period of plasma PC-OOH production was 2.4 +/- 0.4 h, with levels reaching 5.39 +/- 1.50 micromol/L after 6 h of incubation. After supplementation, the induction period increased significantly to 4.2 +/- 0.4 h (P < 0.01), with a lower PC-OOH production of 2.16 +/- 0.90 micromol/L after 6 h (P < 0.05). In this system, plasma ascorbate concentrations were depleted first, followed by loss of bilirubin and alpha-tocopherol and then by the sequential loss of gamma-tocopherol, urate and beta-carotene. These results indicate that beta-carotene supplementation increases the plasma antioxidant capacity of older women.

Effects of injectable vitamin C at weaning and prior to transit on growth performance of early-weaned beef steers

This study investigated the effects of injectable vitamin C (VC) at weaning and prior to transit on growth performance and immune function in early-weaned beef steers. On day 0, 91 Angus × Simmental steers (92 ± 4 kg) were weaned (65 ± 11 d of age), given vaccination boosters, blocked by age, and randomly assigned to weaning (WEAN) treatments: intramuscular injections (20 mL per steer) of VC (250-mg sodium ascorbate per mL; 5 g per steer) or saline (SAL). From days 0 to 48, steers were housed at the Dixon Springs Agricultural Center (Simpson, IL) in pens (six pens; N = 14 to 16 steers per pen) equipped with two to three Vytelle bunks to measure individual daily feed disappearance. On day 49, half of the steers in each WEAN treatment were randomly assigned to an additional injection treatment (20 mL per steer) of VC or SAL prior to transport (TRANS). After administering pretransit injections, all steers were loaded onto a commercial livestock trailer with equal representation of treatments across compartments. Steers were transported for 6 h (approximately 480 km) to the Illinois Beef and Sheep Field Laboratory (Urbana, IL). Upon arrival, steers were sorted into pens (six pens; N = 13 to 17 steers per pen) with 2 Vytelle bunks per pen. Steers were weighed on days 0, 1, 14, 48, 49, 64, 78, 106, and 107. Blood was collected (WEAN = 24 steers per treatment; TRANS = 12 steers per treatment) on days 0, 1, 2, 14, 49 (pre- and posttransit), 50, and 51. Data were analyzed using the MIXED procedure of SAS 9.4 with fixed effects of age block, WEAN, TRANS, and WEAN × TRANS. Plasma ascorbate concentrations were greater (WEAN × time P < 0.01) on days 1 and 2 for steers that received VC at weaning. Similarly, for steers that received VC on day 49 pretransit, ascorbate concentrations were greater (TRANS × time P = 0.04) on days 49 posttransit, 50, and 51. Treatments did not affect (P ≥ 0.13) body weight, average daily gain, or gain to feed throughout the trial. Serum Bovine Viral Diarrhea Virus type 1 and 2 antibody titers on days 14 and 51 were not affected (P ≥ 0.32) by treatment. Injectable VC administered to early-weaned beef steers at the time of weaning or pretransit increased plasma ascorbate concentrations but did not improve growth performance or antibody response to vaccination booster.

Pharmacological Ascorbate Enhances Chemotherapies in Pancreatic Ductal Adenocarcinoma.

Pharmacological ascorbate (P-AscH - , high-dose, intravenous vitamin C) has shown promise as an adjuvant therapy for pancreatic ductal adenocarcinoma (PDAC) treatment. The objective of this study was to determine the effects of P-AscH - when combined with PDAC chemotherapies. Clonogenic survival, combination indices, and DNA damage were determined in human PDAC cell lines treated with P-AscH - in combination with 5-fluorouracil, paclitaxel, or FOLFIRINOX (combination of leucovorin, 5-fluorouracil, irinotecan, oxaliplatin). Tumor volume changes, overall survival, blood analysis, and plasma ascorbate concentration were determined in vivo in mice treated with P-AscH - with or without FOLFIRINOX. P-AscH - combined with 5-fluorouracil, paclitaxel, or FOLFIRINOX significantly reduced clonogenic survival in vitro. The DNA damage, measured by γH2AX protein expression, was increased after treatment with P-AscH - , FOLFIRINOX, and their combination. In vivo, tumor growth rate was significantly reduced by P-AscH - , FOLFIRINOX, and their combination. Overall survival was significantly increased by the combination of P-AscH - and FOLFIRINOX. Treatment with P-AscH - increased red blood cell and hemoglobin values but had no effect on white blood cell counts. Plasma ascorbate concentrations were significantly elevated in mice treated with P-AscH - with or without FOLFIRINOX. The addition of P-AscH - to standard of care chemotherapy has the potential to be an effective adjuvant for PDAC treatment.

PSV-8 Effects of Injectable Vitamin C Immediately Prior to Transit Before Slaughter on Meat Color

Abstract The objective was to evaluate the effects of injectable vitamin C (VC) at transit before slaughter on meat color. The prevalence of dark-cutting beef can be exacerbated by transit and environmental conditions resulting in a less desirable product to consumers. Angus × Simmental steers (n = 48; BW = 670 ± 47 kg) were utilized in a completely randomized design. Steers were stratified by BW within pen and randomly assigned to 1 of 2 treatments: an intramuscular injection of saline immediately prior to transit (CON), or an intramuscular injection of VC (15 g sodium ascorbate) immediately prior to transit (VITC). Blood was collected prior to treatment injection to assess plasma ascorbate status. Following pre-transit treatment injections, steers were transported for approximately 6 h (639 km) and slaughtered at a commercial abattoir. At 24 h postmortem, surface color readings were measured using a HunterLab Miniscan EZ spectrophotometer and marbling scores were evaluated on the left and right longissimus muscle. Data were analyzed using the MIXED and GLIMMIX procedures of SAS 9.4 with fixed effects of treatment, truck, and sire, and random effect of carcass side. Pre-transit plasma ascorbate, body weight, and marbling score were used as covariates. No treatment differences were observed for L* (lightness), a* (redness), and b* (yellowness) values (P &amp;gt; 0.16). Hue angle, saturation index, and prevalence of dark cutters (6% of total carcasses) were not affected by treatment (P &amp;gt; 0.78). Initial plasma ascorbate concentrations did not differ between treatments (P = 0.85) but increased with BW (r = 0.39; P ≤ 0.01). Body weight was correlated (r=0.24 to 0.28; P &amp;lt; 0.02) with HunterLab L*, a*, b*, and saturation index values. Overall, injectable VC administered prior to transit to a harvest facility did not impact meat color of beef steers 24 h postmortem.

The effect of injectable vitamin C and road transit duration on inflammation, muscle fatigue, and performance in pre-conditioned beef steer calves.

This study examined the effects of injectable vitamin C (VC) before transport and duration of transit on feedlot performance, inflammation, and muscle fatigue in cattle. One hundred thirty-two Angus-cross steers (393 ± 4 kg) were stratified by body weight (BW) to a 2 × 2 factorial of intramuscular injection (INJ; 20 mL/steer): VC (250 mg sodium ascorbate/mL) or saline (SAL) and road transit duration (DUR): 18 h (18-h; 1,770 km) or 8 h (8-h; 727 km). On day 0, steers were weighed and given INJ of VC or SAL immediately before transport. Upon return (day 1), BW and blood were collected before steers returned to pens equipped with GrowSafe bunks. Steers were weighed on days 0, 1, 7, 15, 30, 31, 54, and 55. Data were analyzed via ProcMixed of SAS (experimental unit = steer; 32 to 34 steers/treatment) with fixed effects of INJ, DUR, and the interaction. Blood was collected on days −5, 1, 2, 3, and 7 (n = 9 steers/treatment); blood parameters were analyzed as repeated measures with the repeated effect of day. Area under the curve (AUC) for plasma ferric reducing antioxidant power (FRAP) was calculated using R. Final BW was greater for 8 h compared to 18 h (P = 0.05) with no effect of INJ or interaction (P ≥ 0.51). Dry matter intake (DMI) from days 1 to 7 was greater for VC-8, intermediate for VC-18 and SAL-18, and least for SAL-8 (P = 0.02). Overall, DMI tended to be greatest for SAL-18, intermediate for VC-18 and VC-8, and least for SAL-8 (P = 0.08). Days 7 to 31 gain:feed (G:F) was greatest for VC-18 compared to other treatments (INJ × DUR, P = 0.05), and there was no effect of treatment on overall G:F (P ≥ 0. 19). There was no INJ or INJ × DAY (P ≥ 0.17) effect on serum lactate, haptoglobin, or non-esterified fatty acid. However, these blood parameters were greater on day 1 for 18 h compared to 8 h, and both treatments returned to near baseline by day 3 (DUR × DAY, P < 0.01). Plasma ascorbate concentrations on day 1 were greater for VC compared to SAL and returned to baseline by day 2 (INJ × DAY, P < 0.01). Plasma FRAP AUC from days −5 to 3 was greatest for VC-18, intermediate for VC-8 and SAL-8, and least for SAL-18 (INJ × DAY, P = 0.02). This suggests an antioxidant prior to long-haul transit positively influenced antioxidant capacity; however, VC did not improve overall post-transit performance. Although longer transit duration increased indicators of muscle fatigue and inflammation, post-transit performance was not appreciably different between transit durations.

160 Injectable Vitamin C Prior to Transit and Transit Duration Effects on Feedlot Performance, Inflammation, and Muscle Fatigue of Beef Steers

Abstract This study examined the effects of injectable vitamin C (VC) before transport and duration of transit on feedlot performance, inflammation, and muscle fatigue in cattle. One hundred thirty-one, Angus-cross steers (409 ± 4 kg) were stratified by bodyweight (BW) to a 2 × 2 factorial of intramuscular injection (INJ; 20 mL/steer): VC (250 mg sodium ascorbate/mL) or saline (SAL) and road transit duration (DUR): 18 (18; 1,770 km) or 8 h (8; 727 km). On d 0, steers were weighed and received INJ of SAL or VC immediately before transport. Upon return (d 1), BW and blood were collected before steers returned to pens with GrowSafe bunks. Steers were weighed on d 0, 1, 7, 15, 30, 31, 54, and 55. Data were analyzed via ProcMixed of SAS (experimental unit = steer; 32–34 steers/treatment) with fixed effects of INJ, DUR, and the interaction. Blood was collected on d -5, 1, 2, and 3 (9 steers/treatment); blood parameters were analyzed as repeated measures. Average daily gain (ADG) and BW were greater on d 7 and 15 for SAL-18 compared to all other treatments (INJ × DUR, P &amp;lt; 0.01). Final BW, overall ADG, and gain:feed were greater for 18 than 8 (P &amp;lt; 0.01). Injection did not affect BW (P &amp;gt; 0.13) but VC decreased overall dry matter intake compared to SAL (P = 0.03). Steers transported for 18 h had greater serum lactate, haptoglobin, and non-esterified fatty acid concentrations on d 1 compared to steers transported for 8 h (DUR × DAY, P &amp;lt; 0.01). Day 1 plasma ascorbate concentrations were greater for VC and returned to baseline concentrations by d 2 (INJ × DAY, P &amp;lt; 0.01). In contrast to previous work, VC did not improve post-transit performance; however, longer transit duration increased indicators of muscle fatigue and inflammation.

Vitamin C supplementation improves blood pressure and oxidative stress after acute exercise in patients with poorly controlled type 2 diabetes mellitus: A randomized, placebo-controlled, cross-over study.

This study aimed to assess the effect of Vitamin C on blood pressure (BP), and subsequently on oxidative stress and nitric oxide (NO) release, following the low-intensity exercise in the patients. This study included 24 patients with type 2 diabetes mellitus (T2D) (age, 53 ± 7 years; hemoglobin A1c, 10.1% ± 0.9%) randomized into two 6-week daily arms based on the consumption of either placebo or 1000 mg Vitamin C. The crossover trial occurred after a 6-week washout. Before and after both supplementation arms, all patients performed cycling exercise at 33% of peak oxygen consumption for 20 min. BP was measured before, immediately, and 60 min after the exercise. Blood samples were drawn immediately before and after the exercise to determine plasma ascorbate, malondialdehyde (MDA), F2-isoprostanes (F2-IsoPs), and NO concentrations. Data showed significant lower BP in the Vitamin C arm when compared with the placebo arm (systolic BP [SBP] P < 0.001 at every time point, diastolic BP [DBP] P < 0.001 except at immediately after exercise, P < 0.05). Plasma ascorbate concentration (P < 0.05 at every time point) and plasma NO (at resting P < 0.001, immediately after exercise P < 0.05) were significantly increased in the Vitamin C arm than in the placebo arm. Plasma MDA (P < 0.05 at every time point) and F2-IsoPs (P < 0.05 at every time point) concentrations were significantly lower in the Vitamin C arm than in the placebo arm. In addition, data showed significantly lower SBP (P < 0.001 at every time point), DBP (P < 0.001 except at immediately after exercise P < 0.05), plasma MDA (P < 0.001 at every time point), and F2-IsoPs (P < 0.05 at every time point) at post-supplementation than at pre-supplementation. Besides, there were significantly higher plasma ascorbate (P < 0.05 at every time point) and NO (at rest P < 0.01, immediately after exercise P < 0.05) concentrations at post-supplementation than at pre-supplementation. This is in contrast to the placebo treatment arm which demonstrated no statistical difference in all outcomes throughout the experiment. This study suggests that 6-week Vitamin C supplementation decreased preexercise and postexercise BPs, possibly due to improved oxidative stress and NO release. However, exercise had no effect on any outcome measures.

191 Effects of injectable vitamin C at weaning and prior to transit on growth performance and immune function of beef steers

Abstract Ninety-one early-weaned (65 ± 11 d) Angus steers (92 ± 4 kg) were blocked by age to a 2 × 2 factorial examining effects of injectable vitamin C (VC) at weaning and/or prior to transport to the feedlot on antibody titers and growth performance. Injections (20 mL/steer) of VC (250 mg sodium ascorbate/mL) or saline (SAL) were given at time of weaning on d 0 (WEAN) and/or prior to a 6 hr trucking event to a feedlot on d 49 (TRANS). Steers were given booster vaccinations on d 0. Steers were weighed on d 0, 1, 14, 48, 49, 64, 106, and 107. Blood was collected (12 steers/treatment) on d 0, 1, 2, 14, 49 (pre- and post-transit), 50, and 51. Data were analyzed via Proc-Mixed of SAS (experimental unit = steer; n = 22–23/treatment) with fixed effects of block, WEAN, TRANS, and WEAN × TRANS. Plasma ascorbate concentrations for weaning (d 0, 1, and 2) and transit (d 49-pre-trucking, 49-post-trucking, 50, and 51) were analyzed as repeated measures (repeated effect = day). Plasma ascorbate concentrations were greater on d 1 and 2 for steers that received VC at weaning (VC = 19.6, SAL = 8.8 ± 1.26 µM; WEAN × day P &amp;lt; 0.01). Similarly, ascorbate concentrations were greater on d 49 post-trucking, 50, and 51 for steers that received VC pre-transit (TRANS × day P = 0.01). Treatments did not affect bodyweight or average daily gain throughout the trial (P &amp;gt; 0.32). There were no effects of treatment on serum Bovine Viral Diarrhea Virus type 2 antibody titers on d 14 or 51 (P &amp;gt; 0.33). An injection of VC administered to early weaned beef steers at weaning or pre-transit increases plasma ascorbate concentrations but does not improve growth performance or antibody response to vaccination booster.

44 Pre-transit vitamin C injection improves post-transit performance of beef steers

Abstract This study sought to determine the effects of injectable vitamin C (VC), pre- or post-transit, on blood parameters and feedlot performance of beef steers. Seventy-two, Angus-cross steers were blocked by weight (356 ± 18 kg) and randomly assigned to intramuscular injection treatments (20 mL/steer): saline pre- and post-transit (CON), VC (Vet One; 250 mg sodium ascorbate/mL) pre-transit and saline post-transit (PRE), or saline pre-transit and VC post-transit (POST). Following pre-transit injections (d 0), steers were transported for ~18 h (1,675 km). Upon return (d 1), steers received post-transit injections and were sorted into pens (6 steers/pen) equipped with GrowSafe bunks. Steers were weighed on d 0, 1, 7, 30, 31, 56, and 57. Blood was collected on d 0, 1, 2, and 7. Data were analyzed as a randomized complete block design using ProcMixed of SAS (experimental unit = steer; 24 steers/treatment); treatment and block were fixed effects. Blood variables were analyzed as repeated measures. Injectable VC did not affect BW shrink due to transit (P = 0.28). Compared to CON-steers, PRE or POST-steers exhibited greater dry matter intake from d 31-57 and overall (d 1-57; P ≤ 0.02). Average daily gain was greatest for PRE-steers from d 7-31 and overall (P ≤ 0.05), resulting in PRE-steers being heaviest on d 30/31 (P = 0.03) and tending to be heaviest on d 56/57 (P = 0.07). Plasma ascorbate concentrations were decreased immediately post-transit for CON and POST-steers but increased for PRE-steers (treatment × day; P &amp;lt; 0.01). Plasma ferric reducing antioxidant potential and malondialdehyde were decreased post-transit while serum non-esterified fatty acid and haptoglobin were increased; all blood parameters returned to baseline by d 7 (day; P &amp;lt; 0.01). Timing of injectable VC administration appears to influence how cattle respond to transit as pre-transit administration improved subsequent performance of steers.

392 Vitamin C and transit stress in beef cattle

Abstract Transportation of cattle by road is unavoidable in beef production due to segmentation of the industry. Psychological and physical stress associated with transit can negatively impact cattle health and performance upon arrival at their destination. Thus, investigation of resiliency or recovery-based nutritional strategies to mitigate transit stress are warranted. Because oxidative stress is likely linked to transportation stress, one such strategy is antioxidants such as vitamin C (VC). Seventy-two Angus-cross steers (356 ± 18 kg) were used to determine the effects of a pre- versus post-transit VC injection on 56 d feedlot performance. Steers were randomly assigned to intramuscular injection treatments (24 steers/treatment): saline pre- and post-transit (CON), VC (Vet One; 250 mg sodium ascorbate/mL; 5 g sodium ascorbate/steer) pre-transit and saline post-transit (PRE), or saline pre-transit and VC post-transit (POST). Steers were transported for ~18 h (1,675 km) prior to sorting into pens equipped with GrowSafe bunks (6 steers/pen). Blood was collected from 12 steers/treatment on d 0, 1, 2, and 7 for analysis of plasma ascorbate concentrations. Plasma ascorbate concentrations were decreased by ~10% immediately post-transit for CON and POST-steers but increased for PRE-steers; regardless of treatment, concentrations were similar to pre-transit values by d 7 (treatment × day; P &amp;lt; 0.01). Steers that received VC at either timepoint (pre- or post-transit) exhibited greater dry matter intake from d 31–57 and d 1–57 compared to CON-steers (P ≤ 0.02). However, PRE-steers exhibited the greatest average daily gain from d 7–31 and d 1–57 (P ≤ 0.05), resulting in PRE-steers being heaviest on d 30/31 (P = 0.03) and tending to be heaviest on d 56/57 (P = 0.07). Based on these data, timing of nutritional intervention is vital for optimal effectiveness. Furthermore, nutritional strategies that improve antioxidant status prior to long-distance transit events may positively influence post-transit performance.

Low Vitamin C Status in Patients with Cancer Is Associated with Patient and Tumor Characteristics.

Vitamin C (ascorbate) acts as an antioxidant and enzyme cofactor, and plays a vital role in human health. Vitamin C status can be affected by illness, with low levels being associated with disease due to accelerated turnover. However, robust data on the ascorbate status of patients with cancer are sparse. This study aimed to accurately measure ascorbate concentrations in plasma from patients with cancer, and determine associations with patient or tumor characteristics. We recruited 150 fasting patients with cancer (of 199 total recruited) from two cohorts, either prior to cancer surgery or during cancer chemo- or immunotherapy. A significant number of patients with cancer had inadequate plasma ascorbate concentrations. Low plasma status was more prevalent in patients undergoing cancer therapy. Ascorbate status was higher in women than in men, and exercising patients had higher levels than sedentary patients. Our study may prompt increased vigilance of ascorbate status in cancer patients.

Erythrocyte Ascorbate Is a Potential Indicator of Steady-State Plasma Ascorbate Concentrations in Healthy Non-Fasting Individuals.

Plasma vitamin C concentrations fluctuate in response to recent dietary intake; therefore levels are typically determined in the fasting state. Erythrocyte ascorbate concentrations have been shown to be similar to plasma levels, but little is known about the kinetics of ascorbate accumulation in these cells. In this study, we investigated ascorbate uptake into erythrocytes after dietary supplementation with vitamin C and compared it to changes in plasma ascorbate concentrations. Seven individuals with baseline fasting plasma vitamin C concentrations ≥ 50 µmol/L were depleted of vitamin C-containing foods and drinks for one week, and then supplemented with 250 mg vitamin C/day in addition to resuming their normal diet. Fasting or steady-state plasma ascorbate concentrations declined to almost half of their baseline concentration over the week of vitamin C depletion, and then returned to saturation within two days of beginning supplementation. Erythrocyte ascorbate concentrations exhibited a very similar profile to plasma levels, with values ~76% of plasma, and a strong linear correlation (r = 0.89, p < 0.0001). Using a pharmacokinetic study design in six individuals with baseline fasting plasma vitamin C concentrations ≥50 µmol/L, we also showed that, unlike plasma, which peaked between 2 and 4 h following ingestion of 200 mg of vitamin C, erythrocyte ascorbate concentrations did not change in the six hours after supplementation. The data from these two intervention studies indicate that erythrocyte ascorbate concentration provides a stable measure of steady-state plasma ascorbate status and could be used to monitor ascorbate status in healthy non-fasting individuals.

Pre-transit vitamin C injection improves post-transit performance of beef steers

Although cattle can synthesize vitamin C (VC) endogenously, stress may increase VC requirements above the biosynthetic threshold and warrant supplementation. This study investigated the effects of a VC injection delivered before or after a long-distance transit event on blood parameters and feedlot performance of beef steers. Fifty-two days prior to trial initiation, 90 newly weaned, Angus-based steers from a single source were transported to Ames, IA, USA. On day 0, 72 steers (356 ± 17 kg) were blocked by BW and randomly assigned to intramuscular injection treatments (24 steers/treatment): saline injection pre- and post-transit (CON), VC (Vet One, Boise, ID, USA; 5 g sodium ascorbate/steer) injection pre-transit and saline injection post-transit (PRE) or saline injection pre-transit and VC injection post-transit (POST). Following pre-transit treatment injections, steers were transported on a commercial livestock trailer for approximately 18 h (1675 km). Post-transit (day 1), steers were sorted into pens with one GrowSafe bunk/pen (4 pens/treatment; 6 steers/pen). Steers were weighed on day 0, 1, 7, 30, 31, 56 and 57. Blood was collected from 3 steers/pen on day 0, 1, 2 and 7; liver biopsies were performed on the same 3 steers/pen on day 2. Data were analyzed as a randomized complete block design (experimental unit = steer; fixed effects = treatment and block) and blood parameters were analyzed as repeated measures. A pre-transit VC injection improved steer average daily gain from day 7 to 31 (P= 0.05) and overall (day 1 to 57; P= 0.02), resulting in greater BW for PRE-steers on day 30/31 (P= 0.03) and a tendency for greater final BW (day 56/57; P= 0.07). Steers that received VC pre- or post-transit had greater DM intake from day 31 to 57 (P= 0.01) and overall (P= 0.02) v. CON-steers. Plasma ascorbate concentrations were greatest for PRE-steers on day 1 and POST-steers on day 2 (treatment × day; P< 0.01). No interaction or treatment effects were observed for other blood parameters (P≥ 0.21). Plasma ferric-reducing antioxidant potential and malondialdehyde concentrations decreased post-transit (day; P< 0.01), while serum non-esterified fatty acids and haptoglobin concentrations increased post-transit (day; P< 0.01). In general, blood parameters returned to pre-transit values by day 7. Pre-transit administration of injectable VC to beef steers mitigated the decline in plasma ascorbate concentrations and resulted in superior feedlot performance compared to post-transit administration.

In vitro Cytotoxicity and Pharmacokinetic Evaluation of Pharmacological Ascorbate in Dogs.

Background: High-dose, pharmacological ascorbate (P-AscH−) is preferentially cytotoxic to human cancer cells in vitro. Investigations on the efficacy of P-AscH− as an adjuvant treatment for multiple human cancers are on-going, but has yet to be formally investigated in dogs. The primary objectives of this study were to determine the pharmacokinetic (PK) profile of P-AscH− in healthy Beagle dogs and the effects of P-AscH− on canine osteosarcoma cells in vitro.Methods: Eight purpose-bred, healthy, spayed female Beagle dogs, between 20 and 21 months old, and 8–10 kg were administered two doses of P-AscH− (550 or 2,200 mg/kg) via intravenous infusion over 6 h, on separate days. Plasma ascorbate concentrations were measured at 12 time points during and after infusion for PK analysis using nonlinear mixed-effects (NLME) and non-compartmental analysis (NCA). Clonogenic assays were performed on 2 canine osteosarcoma cell lines (D-17 and OSCA-8) and canine primary dermal fibroblasts after exposure to high concentrations of ascorbate (75 pmoles/cell).Results: Plasma ascorbate levels in the dogs peaked at approximately 10 mM following 2,200 mg/kg and returned to baseline 6–8 h after dosing. Minor adverse effects were seen in two dogs. Ascorbate (75 pmoles/cell) significantly decreased survival in both the osteosarcoma cell lines (D-17 63% SD 0.010, P = 0.005; OSCA-8 50% SD 0.086, P = 0.026), compared to normal fibroblasts (27% SD 0.056).Conclusions: Pharmacological ascorbate is preferentially cytotoxic to canine-derived cancer cells. High levels of ascorbate can be safely administered to dogs. Further studies are needed to determine the effects of P-AscH− on canine patients.

Assessment of the Stability of Supraphysiological Ascorbate in Human Blood: Appropriate Handling of Samples from Clinical Trials for Measurements of Pharmacological Ascorbate.

Based on encouraging results from several early-phase clinical trials, there is renewed interest in the use of pharmacological ascorbate (i.e., intravenous administration resulting in >≈10 mM plasma ascorbate concentrations) in combination with standard-of-care cancer treatments including radiation and/or chemotherapy. Under normal, healthy physiological conditions, humans maintain plasma ascorbate concentrations in the range of 40-80 lM. However, in vivo antitumor activity requires supraphysiological plasma concentrations on the order of ≈20 mM. The stability of ascorbate in whole blood has been well studied. The goal of this work was to determine the appropriate handling methods of blood samples, after treatment with pharmacological ascorbate, which allow for the optimal measurement of ascorbate in plasma for dosing verification. Our findings indicate that ascorbate concentrations (mM) are relatively stable in whole blood collected in sodium heparin tubes and stored on ice (or at 4°C) for up to 24 h. After 24 h, ascorbate levels in plasma are relatively stable at 4°C for up to 72 h. At -20°C, plasma concentrations are relatively stable for 2-3 weeks, while at -80°C, ascorbate concentrations in plasma are stable for at least one month. In contrast, patient samples showed better stability when stored as whole blood compared to plasma at 4°C but increasing hemolysis over time may significantly skew ascorbate measurements. Additionally, patient samples can be reliably stored as plasma at -20°C for up to three weeks in either a frost-containing or frost-free environment. This information can guide the collection, processing and storage of clinical samples after pharmacological ascorbate infusions amenable to multi-center clinical trials.

Marginal Ascorbate Status (Hypovitaminosis C) Results in an Attenuated Response to Vitamin C Supplementation.

Inadequate dietary intake of vitamin C results in hypovitaminosis C, defined as a plasma ascorbate concentration ≤23 μmol/L. Our objective was to carry out a retrospective analysis of two vitamin C supplementation studies to determine whether supplementation with 50 mg/day vitamin C is sufficient to restore adequate ascorbate status (≥50 μmol/L) in individuals with hypovitaminosis C. Plasma ascorbate data from 70 young adult males, supplemented with 50 or 200 mg/day vitamin C for up to six weeks, was analyzed. Hypovitaminosis C status was identified based on plasma ascorbate being ≤23 μmol/L and the response of these individuals to vitamin C supplementation was examined. Of the participants consuming 50 mg/day vitamin C for up to six weeks, those with hypovitaminosis C at baseline achieved plasma concentrations of only ~30 μmol/L, whereas the remainder reached ~50 μmol/L. Participants who consumed 200 mg/day vitamin C typically reached saturating concentrations (>65 μmol/L) within one week, while those with hypovitaminosis C required two weeks to reach saturation. Regression modelling indicated that the participants’ initial ascorbate status and body weight explained ~30% of the variability in the final ascorbate concentration. Overall, our analysis revealed that supplementation with 50 mg/day vitamin C, which resulted in a total dietary vitamin C intake of 75 mg/day, was insufficient to achieve adequate plasma ascorbate concentrations in individuals with hypovitaminosis C. Furthermore, increased body weight had a negative impact on ascorbate status.

Amelioration of persistent left ventricular function impairment through increased plasma ascorbate levels following myocardial infarction

Purpose: Percutaneous coronary angioplasty (PCA) has been demonstrated to reduce mortality and morbidity and thereby improve the prognosis of patients undergoing acute myocardial infarctions (AMIs). However, this procedure paradoxically increases the initial damage as the result of a condition known as ‘myocardial reperfusion injury’. Oxidative stress may contribute to the mechanism of this injury. The goal of the present study was to ascertain whether high plasma ascorbate levels could ameliorate the reperfusion injuries that occur after the successful restoration of blood flow. Methods: Patients from three clinical centers of the public health system were included in the study. The groups were formed by either-sex patients with a diagnosis of ST-segment elevation myocardial infarction with an indication for primary PCA. Only the patients who presented with their first myocardial infarction were enrolled. Ascorbate was administered through an infusion given prior to the restoration of the coronary flow, which was then followed by oral treatment with vitamin C (500 mg/12 hours) plus vitamin E (400 IU/day) for 84 days. The left ventricular ejection fraction (LVEF) was determined by using cardiac magnetic resonance on days 6 and 84 following the onset of the reperfusion. In addition, the microvascular function was assessed by an angiographic evaluation using the Thrombolysis In Myocardial Infarction (TIMI) myocardial perfusion grade (TMPG). The results were grouped according to the plasma ascorbate concentration achieved immediately following the onset of reperfusion into either the HA group (high ascorbate, >1 mmol/l) or the LA group (low ascorbate, <1 mmol/l). The biochemical parameters were analyzed throughout the protocol. Results: The LVEF of the HA group was significantly higher than that of the LA group, values on day 84 in the HA group were 33% higher than those of the LA group. The amelioration of the LVEF was accompanied by an improvement in the microvascular dysfunction, after PCA, 95% of the patients in the HA group achieved a TMPG of 2–3, in the LA group only 79% of patients showed a TMPG of 2–3. Conclusions: These data are consistent with the protective effect of high plasma levels of ascorbate against the oxidative challenge caused by reperfusion injury in patients subjected to PCA following an AMI. Further studies are needed to elucidate the mechanism accounting for this beneficial antioxidant effect.

Cytotoxic effects of high concentrations of sodium ascorbate on human myeloid cell lines.

The effect of high doses of intravenous (sodium) ascorbate (ASC) in the treatment of cancer has been controversial although there is growing evidence that ASC in high (pharmacologic) concentrations induces dose-dependent pro-apoptotic death of tumor cells, in vitro. Very few data are available on the role of ASC in the treatment of acute myeloid leukemia (AML). Ascorbate behaves as an antioxidant at low (physiologic), and as pro-oxidant at pharmacologic, concentrations, and this may account for the differences reported in different experimental settings, when human myeloid cell lines, such as HL60, were treated with ASC. Considering the myeloid origin of HL60 cells, and previous literature reports showing that some cell lines belonging to the myeloid lineage could be sensitive to the pro-apoptotic effects of high concentrations of ASC, we investigated in more details the effects of high doses (0.5 to 7mM) of ASC in vitro, on a variety of human myeloid cell lines including the following: HL60, U937, NB4, NB4-R4 (retinoic acid [RA]-resistant), NB4/AsR (ATO-resistant) acute promyelocytic leukemia (APL)-derived cell lines, and K562 as well as on normal CD34+ progenitors derived from human cord blood. Our results indicate that all analyzed cell lines including all-trans retinoic acid (ATRA)- and arsenic trioxide (ATO)-resistant ones are highly sensitive to the cytotoxic, pro-oxidant effects of high doses of ASC, with an average 50% lethal concentration (LC50) of 3mM, depending on cell type, ASC concentration, and time of exposure. Conversely, high doses of ASC neither did exert significant cytotoxic effects nor impaired the differentiation potential in cord blood (CB) CD34+ normal cells. Since plasma ASC concentrations within the millimolar (mM) range can be easily and safely reached by intravenous administration, we conclude that phase I/II clinical trials using high doses of ASC should be designed for patients with advanced/refractory AML and APL.