Plasma antioxidant status after high-dose chemotherapy: a randomized trial of parenteral nutrition in bone marrow transplantation patients

A randomized controlled trial of conventional GVHD prophylaxis with or without teprenone for the prevention of severe acute GVHD

Therapies that effectively suppress graft-versus-host disease (GVHD) without compromising graft-versus-leukemia/lymphoma (GVL) effects is important in allogeneic hematopoietic stem cell transplantation (allo-HSCT) for hematopoietic malignancies. Geranylgeranylacetone (GGA) is a main component of teprenone, a gastric mucosal protectant commonly used in clinical practice. In preclinical models, GGA suppresses proinflammatory cytokines, including interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α), which are associated with GVHD as well as induces thioredoxin-1 (Trx-1), which suppresses GVHD while maintaining GVL effects. Here, we investigated whether the addition of teprenone to standard GVHD prophylaxis could reduce the cumulative incidence of severe acute GVHD (aGVHD) without attenuating GVL effects. This open-label, randomized clinical trial enrolled 40 patients (21 control and 19 teprenone group) who received allo-HSCT between May 2022 and February 2023 in our institution. Patients in the teprenone group received 50 mg of teprenone orally thrice daily for 21 days from the initiation of the conditioning regimen. The cumulative incidence of severe aGVHD by day 100 after allo-HSCT was not significantly different in the two groups (27.9 vs. 16.1%, p = 0.25). The exploratory studies revealed no obvious changes in Trx-1 levels, but the alternations from baseline in IL-1β and TNF-α levels at day 28 after allo-HSCT tended to be lower in the teprenone group. In conclusion, we could not demonstrate that teprenone significantly prevented the development of severe aGVHD. Discrepancy with preclinical model suggests that appropriate dose of teprenone may be necessary to induce the expression of antioxidant enzymes that suppress severe aGVHD. Clinical Trial Registration number:jRCTs 061210072.

hPMSCs prevent erythrocytes dysfunction caused by graft versus host disease via promoting GSH synthesis

BACKGROUND

Oxidative stress is increased in allogeneic hematopoietic stem cell transplant (allo-HSCT) recipients and leads to the development of graft versus host disease (GVHD). Mesenchymal stromal cells (MSCs) can ameliorate GVHD by regulating the function of T cells. However, whether MSCs can modulate erythrocyte antioxidant metabolism and thus reduce GVHD is not known.

METHODS

Forty female BALB/c mice were randomly assigned to four groups: the control, GVHDhigh, hPMSC, and PBS groups. A hypoxanthine/xanthine oxidase system was used to steadily and gradually produce superoxide in an in vitro experiment. A scanning microscope was used to examine the ultrastructure of erythrocytes. Laser diffraction analyses were used to analyze erythrocyte deformability. Western blotting was used to measure the expression of the erythrocyte membrane skeleton proteins Band 3 and β-Spectrin. Corresponding kits were used to assess the levels of oxidative damage and the activity of antioxidant enzymes.

RESULTS

Morphological and deformability defects were significantly increased in erythrocytes from GVHD patients. Band 3 and β-Spectrin expression was also reduced in GVHD patients and model mice. Furthermore, we observed significantly increased oxidative stress-induce injury and decreased antioxidant capability in erythrocytes from both GVHD patients and model mice. Subsequent research showed that human placenta-derived MSC (hPMSC) therapy decreased the GVHD-induced redox imbalance in erythrocytes. Furthermore, our findings suggested that upregulating glucose metabolism promoted both the de novo synthesis and recycling of GSH, which is the primary mechanism by which hPMSCs mediate the increase in antioxidant capacity in erythrocytes.

CONCLUSION

Together, our findings suggest that hPMSCs can increase antioxidant capacity by increasing erythrocyte GSH production and thus ameliorate GVHD.

hUCMSC-derived exosomes protect against GVHD-induced endoplasmic reticulum stress in CD4+ T cells by targeting the miR-16-5p/ATF6/CHOP axis

Exosomes generated from mesenchymal stem cells (MSCs) are thought to be a unique therapeutic strategy for several autoimmune deficiency illnesses. The purpose of this study was to elucidate the protective effects of human umbilical cord mesenchymal stem cell-derived exosomes (hUCMSC-Exo) on CD4+ T cells dysfunction during graft-versus-host disease (GVHD) and to identify the underlying processes involved. Here, we showed that hUCMSC-Exo treatment can effectively attenuate GVHD injury by alleviating redox metabolism disorders and inflammatory cytokine bursts in CD4+ T cells. Furthermore, hUCMSC-Exo ameliorate ER stress and ATF6/CHOP signaling-mediated apoptosis in CD4+ T cells and promote the development of CD4+IL-10+ T cells during GVHD. Moreover, downregulating miR-16-5p in hUCMSC-Exo impaired their ability to prevent CD4+ T cells apoptosis and weakened their ability to promote the differentiation of CD4+IL-10+ T cells. Collectively, the obtained data suggested that hUCMSC-Exo suppress ATF6/CHOP signaling-mediated ER stress and apoptosis in CD4+ T cells, enhance the differentiation of CD4+IL-10+ T cells, and reverse the imbalance of immune homeostasis in the GVHD process by transferring miR-16-5p. Our study provided further evidence that GVHD patients can benefit from hUCMSC-Exo-mediated therapy.

Role of Gut Microbiota and Oxidative Stress in the Progression of Transplant-Related Complications following Hematopoietic Stem Cell Transplantation

Hematopoietic stem cell transplantation (HSCT), also known as bone marrow transplantation, has curative potential for various hematologic malignancies but is associated with risks such as graft-versus-host disease (GvHD), severe bloodstream infection, viral pneumonia, idiopathic pneumonia syndrome (IPS), lung fibrosis, and sinusoidal obstruction syndrome (SOS), which severely deteriorate clinical outcomes and limit the wide application of HSCT. Recent research has provided important insights into the effects of gut microbiota and oxidative stress (OS) on HSCT complications. Therefore, based on recent studies, we describe intestinal dysbiosis and OS in patients with HSCT and review recent molecular findings underlying the causal relationships of gut microbiota, OS, and transplant-related complications, focusing particularly on the involvement of gut microbiota-mediated OS in postengraftment complications. Also, we discuss the use of antioxidative and anti-inflammatory probiotics to manipulate gut microbiota and OS, which have been associated with promising effects in improving HSCT outcomes.

Vitamin requirements during stem cell transplantation: a systematic review

Patients undergoing stem cell transplantation (SCT) are at high risk of malnutrition during the acute post-transplantation period. This systematic review aimed to collate and analyse the evidence for vitamin requirements post-SCT. A systematic search of five databases was conducted to include studies published until March 2021. The review utilised the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) framework. Inclusion criteria consisted of adults undergoing SCT who received vitamin supplementation or had their vitamin levels monitored up to 100 days post-SCT. Studies with paediatric patients or those that looked at vitamin derivates such as folinic acid were excluded. Main outcomes included vitamin deficiency and relevant clinical outcomes. Eleven studies (n = 11) were eligible for inclusion with five rated as neutral quality and six as positive quality. Five studies focused on allogenic SCT, two on autologous SCT and the remaining included a mix of both. Eight studies monitored vitamins levels post-SCT, and seven studies provided vitamin supplementation. Three studies (one provided supplementation) found a high prevalence of vitamin D deficiency (23-60%) prior to SCT. Findings indicate an unclear association between vitamin deficiency and post-SCT complications including acute graft-versus-host-disease, oral mucositis, and mortality. The GRADE certainty of evidence across these outcomes was low or very low. It is unclear if supplementation is needed during SCT, though assessing vitamin D levels prior to transplant should be considered. Further large observational studies or randomised control trials are required to establish vitamin requirements and guide supplementation protocols during SCT.

Targeting Redox Regulation as a Therapeutic Opportunity against Acute Leukemia: Pro-Oxidant Strategy or Antioxidant Approach?

Redox adaptation is essential for human health, as the physiological quantities of non-radical reactive oxygen species operate as the main second messengers to regulate normal redox reactions by controlling several sensors. An abnormal increase reactive oxygen species, called oxidative stress, induces biological injury. For this reason, variations in oxidative stress continue to receive consideration as a possible approach to treat leukemic diseases. However, the intricacy of redox reactions and their effects might be a relevant obstacle; consequently, and alongside approaches aimed at increasing oxidative stress in neoplastic cells, antioxidant strategies have also been suggested for the same purpose. The present review focuses on the molecular processes of anomalous oxidative stress in acute myeloid and acute lymphoblastic leukemias as well as on the oxidative stress-determined pathways implicated in leukemogenic development. Furthermore, we review the effect of chemotherapies on oxidative stress and the possibility that their pharmacological effects might be increased by modifying the intracellular redox equilibrium through a pro-oxidant approach or an antioxidant strategy. Finally, we evaluated the prospect of varying oxidative stress as an efficacious modality to destroy chemoresistant cells using new methodologies. Altering redox conditions may be advantageous for inhibiting genomic variability and the eradication of leukemic clones will promote the treatment of leukemic disease.

The Metabolic Impact of Two Different Parenteral Nutrition Lipid Emulsions in Children after Hematopoietic Stem Cell Transplantation: A Lipidomics Investigation

Hematopoietic stem cell transplantation (HSCT) involves the infusion of either bone marrow or blood cells preceded by toxic chemotherapy. However, there is little knowledge about the clinical benefits of parenteral nutrition (PN) in patients receiving high-dose chemotherapy during HSCT. We investigated the lipidomic profile of plasma and the targeted fatty acid profiles of plasma and erythrocytes in children after HSCT using PN with either a fish oil-based lipid emulsion or a classic soybean oil emulsion. An untargeted liquid chromatography high-resolution mass spectrometry platform connected with a novel in silico annotation algorithm was utilized to determine the most relevant chemical subclasses affected. In addition, we explored the interrelation between the lipidomics profile in plasma, the targeted fatty acid profile in plasma and erythrocytes, several biomarkers of inflammation, and antioxidant defense using an innovative data integration analysis based on Latent Components. We observed that the fish oil-based lipid emulsion had an impact in several lipid subclasses, mainly glycerophosphocholines (PC), glycerophosphoserines (PS), glycerophosphoethanolamines (PE), oxidized PE (O-PE), 1-alkyl,2-acyl PS, lysophosphatidylethanolamines (LPE), oxidized PS (O-PS) and dicarboxylic acids. In contrast, the classic soybean oil emulsion did not. Several connections across the different blocks of data were found and aid in interpreting the impact of the lipid emulsions on metabolic health.

A Pilot Study of Influence of Endurance Training on the Prooxidative and Antioxidant Status of Women after Breast Cancer

The objective of this study was to assess the effect of 8-week long endurance training on the prooxidative–antioxidative status of plasma in women treated for breast cancer. The participants of the study were 12 women after radical mastectomy aged 45 to 56 years (M = 50.6 ± 2.9 years), who had undergone full cancer treatment, on average more than 5 years after the treatment (M = 5.9 ± 0.9 years). Body mass components were measured twice using the method of bioelectric impedance analysis. In order to optimize training loads and to assess the level of exercise tolerance of the participants, the group was subject to an ergospirometric exercise test twice, before (1st) and after (2nd) the completion of the training cycle. The blood was also taken twice for biochemical analyses. Statistically significant differences were noted in the maximum exercise load, the level of which increased in the second test (p < 0.05). No change was observed in the level of antioxidative potential, i.e., the content of some variables, ferric reducing ability of plasma (FRAP), urea, total phenolics, thiobarbituric acid reactive substances (TBARS), and in the blood indices of the body’s nutritional status during the project (total protein, albumin. Endurance training caused an increase in exercise tolerance and did not cause an aggravation of oxidative stress in women undergoing breast cancer treatment.

High-Dose Vitamin C in Advanced-Stage Cancer Patients

High-dose intravenously administered vitamin C (IVC) is widely used in cancer patients by complementary and alternative medicine practitioners. The most frequent indications for IVC therapy result from the belief in its effectiveness as a potent anti-cancer agent which additionally enhances chemosensitivity of cancer cells and reduces chemotherapy-related toxicities and fatigue intensity. In this narrative review, we decided to deal with this issue, trying to answer the question whether there is any scientific evidence supporting the rationale for application of high-dose IVC therapy in advanced-stage cancer patients. Although results obtained from preclinical studies demonstrated that millimolar ascorbate plasma concentrations achievable only after IVC administration were cytotoxic to fast-growing malignant cells and inhibited tumor growth as well as prolonged the survival of laboratory animals, such positive effects were not found in human studies with advanced-stage cancer patients. We also have not found the rationale for the use of IVC to increase the effectiveness of chemotherapy and to reduce the chemotherapy-induced toxicity in the above mentioned group. Nevertheless, in palliative care, high-dose IVC might be considered as a therapy improving the quality of life and reducing cancer-related symptoms, such as fatigue and bone pain. However, because of the absence of placebo-controlled randomized trials on IVC efficacy in advanced-stage cancer patients, the placebo effect cannot be excluded.

Vitamin E and acute graft-versus-host disease after myeloablative allogeneic hematopoietic cell transplantation

OBJECTIVES

Vitamin E has antioxidant and immunomodulatory effects that might influence the development of acute graft-versus-host disease (GvHD). We investigated the association between plasma vitamin E levels and acute GvHD.

METHODS

We studied 115 adults who underwent myeloablative allogeneic hematopoietic cell transplantation between July 2015 and August 2018. Vitamin E was measured by high-performance liquid chromatography in stored plasma samples obtained pre-transplantation at day -23 (±15 days) and post-transplantation at day +28 (±3 days).

RESULTS

Pre-transplantation vitamin E levels were inversely associated with grade II-IV acute GvHD (hazard ratio 0.68 per 10 µmol/L increase, 95% confidence interval [CI]: 0.47-0.98). The association remained after adjustment for known prognostic factors for acute GvHD. Patients with levels below the median had a cumulative incidence of grade II-IV acute GvHD of 46% (CI: 33-59%) versus 21% (CI: 10-32%) in patients with levels above the median. No clear association with non-relapse mortality, relapse, or chronic GvHD was found. Post-transplantation vitamin E levels (measured in 72 [63%] patients) were correlated with pre-transplantation levels (ρ = .31) but were not associated with subsequent grade II-IV acute GvHD.

CONCLUSIONS

High pre-transplantation vitamin E levels were associated with less acute GvHD.

Citrus hystrix Extracts Protect Human Neuronal Cells against High Glucose-Induced Senescence

Citrus hystrix (CH) is a beneficial plant utilized in traditional folk medicine to relieve various health ailments. The antisenescent mechanisms of CH extracts were investigated using human neuroblastoma cells (SH-SY5Y). Phytochemical contents and antioxidant activities of CH extracts were analyzed using a gas chromatograph–mass spectrometer (GC-MS), 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) assay and 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) assay. Effects of CH extracts on high glucose-induced cytotoxicity, reactive oxygen species (ROS) generation, cell cycle arrest and cell cycle-associated proteins were assessed using a 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide tetrazolium (MTT) assay, non-fluorescent 2′, 7′-dichloro-dihydrofluorescein diacetate (H₂DCFDA) assay, flow cytometer and Western blot. The extracts protected neuronal senescence by inhibiting ROS generation. CH extracts induced cell cycle progression by releasing senescent cells from the G1 phase arrest. As the Western blot confirmed, the mechanism involved in cell cycle progression was associated with the downregulation of cyclin D1, phospho-cell division cycle 2 (pcdc2) and phospho-Retinoblastoma (pRb) proteins. Furthermore, the Western blot showed that extracts increased Surtuin 1 (SIRT1) expression by increasing the phosphorylation of Glyceraldehyde 3-phosphate dehydrogenase (GAPDH). Collectively, CH extracts could protect high glucose-induced human neuronal senescence by inducing cell cycle progression and up-regulation of SIRT1, thus leading to the improvement of the neuronal cell functions.

Distinct Regulatory and Effector T Cell Metabolic Demands during Graft-Versus-Host Disease

Despite graft-versus-host disease (GVHD) prophylactic agents, the success and wider utilization of allogeneic hematopoietic stem cell transplantation (allo-HSCT) is limited by GVHD. Increasing donor graft regulatory T cell (Treg):effector T cell (Teff) ratios can substantially reduce GVHD in cancer patients, but pre-HSCT conditioning regimens and GVHD create a challenging inflammatory environment for Treg stability, persistence, and function. Metabolism plays a crucial role in T cell and Treg differentiation, and development of effector function. Although glycolysis is a main driver of allogeneic T cell-driven GVHD, oxidative phosphorylation is a main driver of Treg suppressor function. This review focuses on recent advances in our understanding of Treg metabolism in the context of GVHD, and discusses potential therapeutic applications of Tregs in the prevention or treatment of GVHD in cancer patients.

Thioredoxin-1 confines T cell alloresponse and pathogenicity in graft-versus-host disease

Oxidative stress is elevated in the recipients of allogeneic hematopoietic transplantation (allo-HCT) and likely contributes to the development of graft-versus-host disease (GVHD). GVHD is characterized by activation, expansion, cytokine production and migration of alloreactive donor T cells, and remains a major cause of morbidity and mortality after allo-HCT. Hence, strategies to limit oxidative stress in GVHD are highly desirable. Thioredoxin1 (Trx1) counteracts oxidative stress by scavenging reactive oxygen species (ROS) and regulating other enzymes that metabolize H2O2. The present study sought to elucidate the role of Trx1 in the pathophysiology of GVHD. Using murine and xenograft models of allogeneic bone marrow transplantation (allo-BMT) and genetic (human Trx1-transgenic, Trx1-Tg) as well as pharmacologic (human recombinant Trx1, RTrx1) strategies; we found that Trx1-Tg donor T cells or administration of the recipients with RTrx1 significantly reduced GVHD severity. Mechanistically, we observed RTrx1 reduced ROS accumulation and cytokine production of mouse and human T cells in response to alloantigen stimulation in vitro. In allo-BMT settings, we found that Trx1-Tg or RTrx1 decreased downstream signaling molecules including NFκB activation and T-bet expression, and reduced proliferation, IFN-γ production and ROS accumulation in donor T cells within GVHD target organs. More importantly, administration of RTrx1 did not impair the graft-versus-leukemia (GVL) effect. Taken together, the current work provides a strong rationale and demonstrates feasibility to target the ROS pathway, which can be readily translated into clinic.

The mercapturomic profile of health and non-communicable diseases

The mercapturate pathway is a unique metabolic circuitry that detoxifies electrophiles upon adducts formation with glutathione. Since its discovery over a century ago, most of the knowledge on the mercapturate pathway has been provided from biomonitoring studies on environmental exposure to toxicants. However, the mercapturate pathway-related metabolites that is formed in humans—the mercapturomic profile—in health and disease is yet to be established. In this paper, we put forward the hypothesis that these metabolites are key pathophysiologic factors behind the onset and development of non-communicable chronic inflammatory diseases. This review goes from the evidence in the formation of endogenous metabolites undergoing the mercapturate pathway to the methodologies for their assessment and their association with cancer and respiratory, neurologic and cardiometabolic diseases.

Reduced Plasma Amino Acid Levels During Allogeneic Hematopoietic Stem Cell Transplantation Are Associated with Systemic Inflammation and Treatment-Related Complications

Patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT) are challenged by cytotoxic effects of the conditioning regimen, resulting in tissue damage, systemic inflammation, and increased metabolic demands for amino acids to regenerate damaged tissues, reconstitute hematopoietic cells, and establish antioxidant defenses. To date, few studies have addressed the role of plasma amino acid (PAA) levels during transplantation, and it remains unknown if amino acid deficiency can aggravate treatment-related morbidity. We determined plasma levels of the 23 human amino acids in 80 HSCT recipients (age 1.1 to 55.4 years) before conditioning and on days +7 and +21 post-transplant along with C-reactive protein (CRP) and IL-6 levels on day +7. Significant changes were observed in plasma concentrations of several human amino acids during HSCT. On day +7, numerous amino acids were inversely correlated with both CRP and IL-6, including glutamic acid, serine, alanine, glutamine, arginine, cysteine, glycine, histidine, lysine, tryptophan, threonine, taurine, proline, and methionine (r = -.22 to -.66; all P < .05). Patients who developed sinusoidal obstruction syndrome (SOS) had significantly lower mean total PAA levels compared with patients without SOS (2013 ng/L [95% confidence interval (CI), 1709 to 2318 ng/L] versus 2706 ng/L [95% CI, 2261 to 3150 ng/L]; P = .006), along with lower individual levels of glutamic acid, serine, arginine, glycine, lysine, valine, tryptophan, threonine, and proline on day +7 (all P < .05). Patients with severe acute graft-versus-host disease had a lower mean total PAA level (1922 ng/L [95% CI, 1738 to 2106 ng/L] versus 2649 ng/L [95% CI, 2244 to 3055 ng/L]; P = .014) and lower levels of serine, glutamine, cysteine, glycine, lysine, and threonine on day +7 (all P < .05). These results indicate a relationship between low concentrations of certain amino acids and the risk of treatment-related complications.

Amino acid modified [70] fullerene derivatives with high radical scavenging activity as promising bodyguards for chemotherapy protection

Despite the great efforts for tumor therapy in the last decades, currently chemotherapy induced toxicity remains a formidable problem for cancer patients, and it usually prohibits the cancer therapy from successful completion due to severe side effects. In general, the main side effects of chemotherapeutic agents are from the as-produced reactive oxygen species (ROS) that not only harm the tumor cells but also damage the patients’ organs. Here we report the application of amino acid derivatives of fullerene (AADF) in the chemotherapy which strongly scavenge the excess ROS to protect the tested mice against the chemotherapy-induced hepatotoxicity and cardiotoxicity. Two amino acids, i.e., L-lysine and β-alanine were separately employed to chemically modify C₇₀ fullerene, and L-lysine derivative of fullerene (C₇₀-Lys) exhibits superior radical scavenging activity to β-alanine derivative of C₇₀ (C₇₀-Ala). As expected, C₇₀-Lys show much better protective effect than C₇₀-Ala against the chemotherapy injuries in vivo, which is verified by various histopathological, haematological examinations and antioxidative enzyme studies. Moreover, the L-glutathione level is increased and the cytochrome P-450 2E1 expression is inhibited. They are potentially developed as promising bodyguards for chemotherapy protection.

Intravenous Vitamin C for Cancer Therapy - Identifying the Current Gaps in Our Knowledge

The use of intravenous vitamin C (IVC) for cancer therapy has long been an area of intense controversy. Despite this, high dose IVC has been administered for decades by complementary health care practitioners and physicians, with little evidence base resulting in inconsistent clinical practice. In this review we pose a series of questions of relevance to both researchers and clinicians, and also patients themselves, in order to identify current gaps in our knowledge. These questions include: Do oncology patients have compromised vitamin C status? Is intravenous the optimal route of vitamin C administration? Is IVC safe? Does IVC interfere with chemotherapy or radiotherapy? Does IVC decrease the toxic side effects of chemotherapy and improve quality of life? What are the relevant mechanisms of action of IVC? What are the optimal doses, frequency, and duration of IVC therapy? Researchers have made massive strides over the last 20 years and have addressed many of these important aspects, such as the best route for administration, safety, interactions with chemotherapy, quality of life, and potential mechanisms of action. However, we still do not know the answers to a number of fundamental questions around best clinical practice, such as how much, how often and for how long to administer IVC to oncology patients. These questions point the way forward for both basic research and future clinical trials.

Implications of plasma thiol redox in disease

Thiol groups are crucially involved in signaling/homeostasis through oxidation, reduction, and disulphide exchange. The overall thiol pool is the resultant of several individual pools of small compounds (e.g. cysteine), peptides (e.g. glutathione), and thiol proteins (e.g. thioredoxin (Trx)), which are not in equilibrium and present specific oxidized/reduced ratios. This review addresses mechanisms and implications of circulating plasma thiol/disulphide redox pools, which are involved in several physiologic processes and explored as disease biomarkers. Thiol pools are regulated by mechanisms linked to their intrinsic reactivity against oxidants, concentration of antioxidants, thiol-disulphide exchange rates, and their dynamic release/removal from plasma. Major thiol couples determining plasma redox potential (Eh) are reduced cysteine (CyS)/cystine (the disulphide form of cysteine) (CySS), followed by GSH/disulphide-oxidized glutathione (GSSG). Hydrogen peroxide and hypohalous acids are the main plasma oxidants, while water-soluble and lipid-soluble small molecules are the main antioxidants. The thiol proteome and thiol-oxidoreductases are emerging investigative areas given their specific disease-related responses (e.g. protein disulphide isomerases (PDIs) in thrombosis). Plasma cysteine and glutathione redox couples exhibit pro-oxidant changes directly correlated with ageing/age-related diseases. We further discuss changes in thiol-disulphide redox state in specific groups of diseases: cardiovascular, cancer, and neurodegenerative. These results indicate association with the disease states, although not yet clear-cut to yield specific biomarkers. We also highlight mechanisms whereby thiol pools affect atherosclerosis pathophysiology. Overall, it is unlikely that a single measurement provides global assessment of plasma oxidative stress. Rather, assessment of individual thiol pools and thiol-proteins specific to any given condition has more solid and logical perspective to yield novel relevant information on disease risk and prognosis.

Intravenous vitamin C in the supportive care of cancer patients: a review and rational approach

This article reviews intravenous vitamin C (IV C) in cancer care and offers a rational approach to enable medical oncologists and integrative practitioners to safely provide IV C combined with oral vitamin C to patients. The use of IV C is a safe supportive intervention to decrease inflammation in the patient and to improve symptoms related to antioxidant deficiency, disease processes, and side effects of standard cancer treatments. A proposed rationale, together with relevant clinical safety considerations for the application of IV C in oncologic supportive care, is provided.

Disulfide bond based polymeric drug carriers for cancer chemotherapy and relevant redox environments in mammals

Increasing numbers of disulfide linkage-employing polymeric drug carriers that utilize the reversible peculiarity of this unique covalent bond have been reported. The reduction-sensitive disulfide bond is usually employed as a linkage between hydrophilic and hydrophobic polymers, polymers and drugs, or as cross-linkers in polymeric drug carriers. These polymeric drug carriers are designed to exploit the significant redox potential difference between the reducing intracellular environments and relatively oxidizing extracellular spaces. In addition, these drug carriers can release a considerable amount of anticancer drug in response to the reducing environment when they reach tumor tissues, effectively improving antitumor efficacy. This review focuses on various disulfide linkage-employing polymeric drug carriers. Important redox thiol pools, including GSH/GSSG, Cys/CySS, and Trx1, as well as redox environments in mammals, will be introduced.

Neoadjuvant combination therapy with trastuzumab in a breast cancer patient with synchronous rectal carcinoma: a case report and biomarker study

We report a patient who presented with synchronous second primary human epidermal growth factor receptor (HER)-2-positive breast cancer and rectal cancer that both required simultaneous neoadjuvant therapy. A modified regimen combining anti-HER-2 monoclonal antibody trastuzumab with chemotherapy and external beam radiation was selected. An organ-preserving surgical procedure was possible both in the breast and the rectum. Citrulline decreased rapidly after the start of the treatment, and then gradually returned to pre-treatment levels after the completion of chemoradiation. Urinary neopterin concentrations exhibited a fluctuating course. Both serum neopterin and C-reactive protein concentrations were more or less stable during the initial administration of trastuzumab, paclitaxel and carboplatin and then increased steeply during chemoradiation and subsequently declined to pre-treatment levels during the weekly trastuzumab administration. Changes were observed in the serum retinol concentrations. A decline in lymphocyte counts was accompanied by marked changes in peripheral blood cell count-derived ratios. The present case report demonstrates a successful combination of two neoadjuvant regimens in a patient with two synchronous different second primary tumors. Data from this case also illustrate the use of biomarkers for monitoring of intensive therapeutic regimens in medical and radiation oncology.

Effects of treatment with chemotherapy and/or tamoxifen on the biomarkers of cardiac injury and oxidative stress in women with breast cancer

There has been an increase in deaths from cardiovascular diseases following breast cancer therapy. Evidence has shown that this outcome is, in part, associated with cardiotoxicity induced by the chemotherapeutic drugs and the increase in oxidative stress. The aim of this study was to evaluate the effects of chemotherapy and hormone therapy with tamoxifen on the biomarkers of cardiac injury and oxidative stress in women with breast cancer.Thirty women were followed-up for 1 year and were divided into 3 groups according to the treatment protocol: women treated only with tamoxifen and clinical follow up for 12 months (Tam, n = 10); women treated only with chemotherapy for 6 months with clinical follow up for an additional 6-month period (Chemo, n = 10); and women who received chemotherapy for 6 months followed by a 6-month period only with tamoxifen therapy and clinical follow up (Chemo + Tam, n = 10). Analysis of the blood levels of cardiac troponin I (cTnI), advanced oxidation protein products (AOPP) and the activity of the plasmatic isoform of the antioxidant enzyme glutathione peroxidase (GPx) was performed before treatment (T0) and at 6 (T6) and 12 (T12) months after treatment.The Chemo group showed higher levels of cTnI (0.065 ± 0.006 ng/mL, P < .05) and AOPP (4.99 ± 0.84 μmol/L, P < .05) and reduced GPx activity (24.4 ± 1.1 nM/min/mL, P < .05) at T12 than the Tam group (cTnI: 0.031 ± 0.001 ng/mL; AOPP: 1.40 ± 0.10 μmol/L; GPx: 28.0 ± 0.7 nM/min/mL) and Chemo + Tam group (cTnI: 0.037 ± 0.002 ng/mL; AOPP: 2.53 ± 0.30 μmol/L; GPx: 29.5 ± 1.0 nM/min/mL).These data support the hypothesis that long-term oxidative stress after chemotherapy may have an impact on cardiovascular diseases and that tamoxifen has cardioprotective effects.

Irinotecan chemotherapy-induced intestinal oxidative stress: Underlying causes of disturbed mucosal water and electrolyte transport

Irinotecan, a chemotherapy drug, can cause acute diarrhea immediately after administration. Hence, the present study was designed to investigate the gastrointestinal (GI) disturbances after an intraperitoneal (IP) administration of irinotecan in rats.Twenty Wistar rats were separated into two groups of ten. Group A was considered as a control group (NaCl, 0.9%). Group B was treated with irinotecan at a single dose of 200mgkg^-1. The rats were observed for defecation. For the enteropooling test, the animals were sacrificed by decapitation 1h post-treatment. The small intestine was excised and the fluid was milked into a graduated tube and the volume was measured. After centrifugation of intraluminal liquid, the electrolyte concentrations in the supernatants were measured by flame photometry. Oxidative stress parameters and intracellular mediators as well as the MPO activity were determined in intestinal mucosa by colorimetric methods Our result indicated that irinotecan produces an intestinal fluid accumulation and electrolyte transport disorders. These effects were associated with augmented intestinal MPO activity and oxidative damage such as an elevation of MDA production and a depletion of enzymatic and non-enzymatic antioxidants. More than that, drug administration provoked intracellular mediator disturbances such as a free iron, H₂O₂ and calcium levels. In conclusion, the data suggest that irinotecan caused a gastrointestinal stress via oxidative stress-induced disturbances in water and electrolyte transport in the intestinal mucosa in rats.

Nutrition Issues in Hematopoietic Stem Cell Transplantation: State of the Art

There have been many changes in hematopoietic stem cell transplantation (HSCT) that affect the patient's nutrition support. In the early 1970s, allogeneic transplants were the most common types of HSCTs; today, autologous transplants are the most common. Bone marrow, peripheral blood, and umbilical cord blood all now serve as sources of stem cells. Conditioning therapies include myeloablative, reduced-intensity myeloablative, and nonmyeloablative regimens. New medications are being developed and used to minimize the toxicities of the conditioning therapy and to minimize infectious complications. Supportive therapies for renal and liver complications have changed. In the past, HSCT patients received parenteral nutrition (PN) throughout their hospitalization and sometimes as home therapy. Because of medical complications and cost issues associated with PN, many centers are now working to use less PN and increase use of enteral nutrition. The immunosuppressed diet has changed from a sterile diet prepared under laminar-flow hoods to a more liberal diet that avoids high-risk foods and emphasizes safety in food handling practices. This article will review these changes in HSCT and the impact of these changes on the nutrition support of the patient.

Myeloperoxidase Enhances Etoposide and Mitoxantrone-Mediated DNA Damage: A Target for Myeloprotection in Cancer Chemotherapy

Myeloperoxidase is expressed exclusively in granulocytes and immature myeloid cells and transforms the topoisomerase II (TOP2) poisons etoposide and mitoxantrone to chemical forms that have altered DNA damaging properties. TOP2 poisons are valuable and widely used anticancer drugs, but they are associated with the occurrence of secondary acute myeloid leukemias. These factors have led to the hypothesis that myeloperoxidase inhibition could protect hematopoietic cells from TOP2 poison-mediated genotoxic damage and, therefore, reduce the rate of therapy-related leukemia. We show here that myeloperoxidase activity leads to elevated accumulation of etoposide- and mitoxantrone-induced TOP2A and TOP2B-DNA covalent complexes in cells, which are converted to DNA double-strand breaks. For both drugs, the effect of myeloperoxidase activity was greater for TOP2B than for TOP2A. This is a significant finding because TOP2B has been linked to genetic damage associated with leukemic transformation, including etoposide-induced chromosomal breaks at the MLL and RUNX1 loci. Glutathione depletion, mimicking in vivo conditions experienced during chemotherapy treatment, elicited further MPO-dependent increase in TOP2A and especially TOP2B-DNA complexes and DNA double-strand break formation. Together these results support targeting myeloperoxidase activity to reduce genetic damage leading to therapy-related leukemia, a possibility that is enhanced by the recent development of novel specific myeloperoxidase inhibitors for use in inflammatory diseases involving neutrophil infiltration.

Parenteral trace element provision: recent clinical research and practical conclusions

The aim of this systematic review (PubMed, www.ncbi.nlm.nih.gov/pubmed and Cochrane, www.cochrane.org; last entry 31 December 2014) was to present data from recent clinical studies investigating parenteral trace element provision in adult patients and to draw conclusions for clinical practice. Important physiological functions in human metabolism are known for nine trace elements: selenium, zinc, copper, manganese, chromium, iron, molybdenum, iodine and fluoride. Lack of, or an insufficient supply of, these trace elements in nutrition therapy over a prolonged period is associated with trace element deprivation, which may lead to a deterioration of existing clinical symptoms and/or the development of characteristic malnutrition syndromes. Therefore, all parenteral nutrition prescriptions should include a daily dose of trace elements. To avoid trace element deprivation or imbalances, physiological doses are recommended.

Fatigue and Oxidative Stress in Children Undergoing Leukemia Treatment

Fatigue is a frequent and distressing symptom in children undergoing leukemia treatment; however, little is known about factors influencing this symptom. Antioxidants such as glutathione can decrease symptom severity in adult oncology patients, but no study has evaluated antioxidants' effects on symptoms in pediatric oncology patients. This study describes fatigue patterns and associations of fatigue with antioxidants represented by reduced glutathione (GSH) and the reduced/oxidized glutathione (GSH/GSSG) ratio among children receiving leukemia treatment. A repeated measures design assessed fatigue and antioxidants among 38 children from two large U.S. cancer centers. Fatigue was assessed among school-age children and by parent proxy among young children. Antioxidants (GSH and GSH/GSSG ratio) were assessed from cerebrospinal fluid at four phases during leukemia treatment. Young children had a steady decline of fatigue from the end of induction treatment through the continuation phase of treatment, but no significant changes were noted among the school-age children. Mean antioxidant scores varied slightly over time; however, the GSH/GSSG ratios in these children were significantly lower than the normal ratio. Mean GSH/GSSG ratios significantly correlated to fatigue scores of the school-age children during early phases of treatment. Children with low mean GSH/GSSG ratios demonstrated oxidative stress. The low ratios noted early in therapy were significantly correlated with higher fatigue scores during induction and postinduction treatment phases. This finding suggests that increased oxidative stress during the more intensive phases of therapy may explain the experience of fatigue children report.

Changes in Antioxidant Defense System Using Different Lipid Emulsions in Parenteral Nutrition in Children after Hematopoietic Stem Cell Transplantation

Background: Traditionally, lipids used in parenteral nutrition (PN) are based on ω-6 fatty acid-rich vegetable oils, such as soybean oil, with potential adverse effects involving oxidative stress. Methods: We evaluated the antioxidant defense system in children, after hematopoietic stem cell transplantation (HSCT), who were randomized to use a lipid emulsion with fish oil or soybean oil. Blood samples at baseline, at 10 days, and at the end of the PN were taken to analyze plasma retinol, α-tocopherol, β-carotene, coenzyme Q9 and coenzyme Q10 levels, and catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPOX), and superoxide dismutase (SOD) levels in lysed erythrocytes. Results: An increase in plasma α-tocopherol levels in the group of patients receiving the fish oil-containing emulsion (FO) compared with the group receiving the soybean emulsion was observed at day 10 of PN. Concurrently, plasma α-tocopherol increased in the FO group and β-carotene decreased in both groups at day 10 compared with baseline levels, being more significant in the group receiving the FO emulsion. Conclusion: FO-containing emulsions in PN could improve the antioxidant profile by increasing levels of α-tocopherol in children after HSCT who are at higher risk of suffering oxidative stress and metabolic disorders.

High-dose intravenous vitamin C combined with cytotoxic chemotherapy in patients with advanced cancer: a phase I-II clinical trial

Background

Biological and some clinical evidence suggest that high-dose intravenous vitamin C (IVC) could increase the effectiveness of cancer chemotherapy. IVC is widely used by integrative and complementary cancer therapists, but rigorous data are lacking as to its safety and which cancers and chemotherapy regimens would be the most promising to investigate in detail.

Methods and Findings

We carried out a phase I-II safety, tolerability, pharmacokinetic and efficacy trial of IVC combined with chemotherapy in patients whose treating oncologist judged that standard-of-care or off-label chemotherapy offered less than a 33% likelihood of a meaningful response. We documented adverse events and toxicity associated with IVC infusions, determined pre- and post-chemotherapy vitamin C and oxalic acid pharmacokinetic profiles, and monitored objective clinical responses, mood and quality of life. Fourteen patients were enrolled. IVC was safe and generally well tolerated, although some patients experienced transient adverse events during or after IVC infusions. The pre- and post-chemotherapy pharmacokinetic profiles suggested that tissue uptake of vitamin C increases after chemotherapy, with no increase in urinary oxalic acid excretion. Three patients with different types of cancer experienced unexpected transient stable disease, increased energy and functional improvement.

Conclusions

Despite IVC’s biological and clinical plausibility, career cancer investigators currently ignore it while integrative cancer therapists use it widely but without reporting the kind of clinical data that is normally gathered in cancer drug development. The present study neither proves nor disproves IVC’s value in cancer therapy, but it provides practical information, and indicates a feasible way to evaluate this plausible but unproven therapy in an academic environment that is currently uninterested in it. If carried out in sufficient numbers, simple studies like this one could identify specific clusters of cancer type, chemotherapy regimen and IVC in which exceptional responses occur frequently enough to justify appropriately focused clinical trials.

Trial Registration

ClinicalTrials.gov NCT01050621

Thiol/redox metabolomic profiling implicates GSH dysregulation in early experimental graft versus host disease (GVHD)

Graft-versus-host disease (GVHD) is a common complication of allogeneic bone marrow transplantation (BMT). Upregulation of inflammatory cytokines precedes the clinical presentation of GVHD and predicts its severity. In this report, thiol/redox metabolomics was used to identify metabolic perturbations associated with early preclinical (Day+4) and clinical (Day+10) stages of GVHD by comparing effects in Syngeneic (Syn; major histocompatibility complex- identical) and allogeneic transplant recipients (Allo BMT) in experimental models. While most metabolic changes were similar in both groups, plasma glutathione (GSH) was significantly decreased, and GSH disulfide (GSSG) was increased after allogeneic compared to syngeneic recipient and non-transplant controls. The early oxidation of the plasma GSH/GSSG redox couple was also observed irrespective of radiation conditioning treatment and was accompanied by significant rise in hepatic protein oxidative damage and ROS generation. Despite a significant rise in oxidative stress, compensatory increase in hepatic GSH synthesis was absent following Allo BMT. Early shifts in hepatic oxidative stress and plasma GSH loss preceded a statistically significant rise in TNF-α. To identify metabolomic biomarkers of hepatic GVHD injury, plasma metabolite concentrations analyzed at Day+10 were correlated with hepatic organ injury. GSSG (oxidized GSH) and β-alanine, were positively correlated, and plasma GSH cysteinylglycine, and branched chain amino acids were inversely correlated with hepatic injury. Although changes in plasma concentrations of cysteine, cystathionine (GSH precursors) and cysteinylglycine (a GSH catabolite) were not significant by univariate analysis, principal component analysis (PCA) indicated that accumulation of these metabolites after Allo BMT contributed significantly to early GVHD in contrast to Syn BMT. In conclusion, thiol/redox metabolomic profiling implicates that early dysregulation of host hepatic GSH metabolism and oxidative stress in sub-clinical GVHD before elevated TNF-α levels is associated with GVHD pathogenesis. Future studies will probe the mechanisms for these changes and examine the potential of antioxidant intervention strategies to modulate GVHD.

Oxidative stress and neurodegenerative disorders

Living cells continually generate reactive oxygen species (ROS) through the respiratory chain during energetic metabolism. ROS at low or moderate concentration can play important physiological roles. However, an excessive amount of ROS under oxidative stress would be extremely deleterious. The central nervous system (CNS) is particularly vulnerable to oxidative stress due to its high oxygen consumption, weakly antioxidative systems and the terminal-differentiation characteristic of neurons. Thus, oxidative stress elicits various neurodegenerative diseases. In addition, chemotherapy could result in severe side effects on the CNS and peripheral nervous system (PNS) of cancer patients, and a growing body of evidence demonstrates the involvement of ROS in drug-induced neurotoxicities as well. Therefore, development of antioxidants as neuroprotective drugs is a potentially beneficial strategy for clinical therapy. In this review, we summarize the source, balance maintenance and physiologic functions of ROS, oxidative stress and its toxic mechanisms underlying a number of neurodegenerative diseases, and the possible involvement of ROS in chemotherapy-induced toxicity to the CNS and PNS. We ultimately assess the value for antioxidants as neuroprotective drugs and provide our comments on the unmet needs.

Regulation of prostate cancer cell invasion by modulation of extra- and intracellular redox balance

Recent metabolic profiles of human prostate cancer tissues showed a significant increase in cysteine (Cys) and a significant decrease in reduced glutathione (GSH) during cancer progression from low- to high-grade Gleason scores. Cys is primarily localized extracellularly, whereas GSH is present mostly inside the cell. We hypothesized that extra- or intracellular redox state alterations differentially regulate cell invasion in PC3 prostate carcinoma cells versus PrEC normal prostate epithelial cells. Cells were exposed to media with calculated Cys/CySS redox potentials (E(h)CySS) ranging from -60 to -180mV. After 3h exposure to a reducing extracellular redox state (E(h)CySS=-180mV), matrix metalloprotease (MMP), gelatinase, and NADPH oxidase activities increased, correlating with increases in cell invasion, cell migration, and extracellular hydrogen peroxide levels in PC3 cells but not PrECs. Knockdown of NADPH oxidase or MMP with silencing RNAs during cultivation with E(h)CySS=-180mV medium significantly decreased PC3 cell invasion. Modulation of extra- and intracellular redox states by exposure of PC3 cells to Cys/CySS-free medium (approx E(h)CySS=-87mV) containing 500μMN-acetylcysteine resulted in a more reducing intracellular redox state and a significant decrease in cell invasive ability. The decrease in PC3 cell invasion induced by these conditions correlated with a decrease in MMP activity. Our studies demonstrated that an extracellular redox state that was more reducing than a physiologic microenvironment redox state increased PC3 cancer cell invasive ability, whereas an intracellular redox environmental that was more reducing than an intracellular physiologic redox state inhibited PC3 cell invasive ability.

Sulfur amino acid-free diet results in increased glutamate in human midbrain: a pilot magnetic resonance spectroscopic study

OBJECTIVE

This pilot study was designed to determine if metabolic effects in different brain regions (left and right parietal lobes, midbrain) caused by 3 d of food consumption without methionine or cysteine could be detected by proton magnetic resonance spectroscopy.

METHODS

Healthy individuals 18 to 36 y old (n = 8) were studied by magnetic resonance spectroscopy after receiving a diet with adequate sulfur amino acids (SAAs) or with zero SAA for 3 d. Pulse sequences were used to selectively measure glutathione (GSH), and linear combination modeling of spectra was used to measure other high-abundance brain metabolites and expressed relative to creatine (Cr).

RESULTS

Although dietary SAAs are required to maintain GSH, the 3-d SAA insufficiency resulted in no significant change in GSH/Cr in the three brain regions. Principal component analysis of 16 metabolites measured by linear combination modeling showed that the metabolic pattern in the midbrain, but not in the parietal lobes, was distinguished according to the dietary SAAs. Multivariate statistical analysis showed that the major discriminating factors were signals of glutamate/Cr, (glutamate + glutamine)/Cr, and myoinositol/Cr. Correlation analyses between midbrain metabolites and GSH-related metabolites in plasma showed that midbrain glutamate/Cr had an inverse correlation with plasma cystine.

CONCLUSION

The data show that magnetic resonance spectroscopy is a non-invasive tool suitable for nutritional assessment and suggest that nutritional imbalance caused by 3 d of SAA-free food more selectively affects the midbrain than the parietal lobes.

Evaluation of oxidative and antioxidative parameters in pediatric hematopoietic SCT patients

Conditioning regimens preceding hematopoietic SCT (HSCT) usually consist of high-dose chemotherapy. Chemotherapy and radiation therapy are associated with increased formation of free radicals and depletion of critical plasma and tissue antioxidants. Oxidative stress and antioxidant depletion have been described during the transplantation period in HSCT patients. In a limited number of studies, it was observed that the conditioning regimen resulted in oxidative stress and antioxidant depletion in HSCT patients. The objective of this study was to look for further evidence of oxidative stress and antioxidant status in pediatric HSCT patients. In this study, blood samples were collected from 21 pediatric allo-HSCT patients before and after conditioning therapy. Erythrocyte and plasma malondialdehyde (MDA) levels, erythrocyte reduced and oxidized glutathione (GSH) levels, erythrocyte antioxidant enzymes activities, plasma α-tocopherol and β-carotene levels were determined. After high-dose chemotherapy, erythrocyte and plasma MDA levels increased. Reduced GSH levels decreased whereas oxidized GSH levels increased first and then decreased significantly compared with the values before the chemotherapy regimen. It was also observed that catalase, superoxide dismutase and GSH-S-transferase activities decreased, but there was no change in GSH peroxidase activity. On the other hand, plasma α-tocopherol levels increased, but β-carotene levels did not change.

Use of defibrotide in the treatment and prevention of veno-occlusive disease

Hepatic veno-occlusive disease (VOD) is one of the most important complications of high-dose chemotherapy and stem cell transplantation. VOD is a clinical syndrome characterized by jaundice, hepatic enlargement and fluid retention typically seen by day +30 after transplantation. Severe VOD is complicated by multiorgan failure and a high mortality rate approaching 100%. Defibrotide (DF) is a novel agent with both antithrombotic and fibrinolytic properties that has emerged as an effective therapy for severe VOD. In Phase II studies, treatment of severe VOD has resulted in complete responses of 30-60% and survival past day 100 ranging between 32-50%. A Phase III, historically controlled study of DF for treatment of severe VOD has recently been completed and results are awaited with interest. In addition, DF may be effective prophylaxis for VOD in high-risk patients. This review will focus on a summary of the pharmacology of DF and the clinical evidence for its use in VOD.

Serum retinol, alpha-tocopherol and systemic inflammatory response in metastatic colorectal carcinoma patients treated with combination chemotherapy and cetuximab

Cetuximab is a chimeric antibody registered for the therapy of advanced colorectal carcinoma. Cancer and anticancer therapy are associated with oxidative stress, and disorders of antioxidant balance may be involved in the toxicity associated with anticancer treatment. The aim of the present study was to investigate the changes of serum retinol, alpha-tocopherol and C-reactive protein during the first month of treatment with cetuximab and chemotherapy. Twenty-five consecutive patients with metastatic colorectal carcinoma treated with a combination of chemotherapy and cetuximab were included in the present study. Serum retinol and alpha-tocopherol were determined by high-performance liquid chromatography and serum C-reactive protein was determined using commercial kits. Significant correlation was observed between baseline concentrations of retinol and C-reactive protein (r(s)=-0.54, p<0.01). Median survival of patients who had baseline serum retinol below 1.25 µmol/L was 10 mo compared to 18 mo for patients who had serum retinol equal or above 1.25 µmol/L (p<0.05); median survival of patients who had serum C-reactive protein below 24 mg/L was significantly longer compared to patients with C-reactive protein levels equal or above 24 mg/L (18 vs. 7 mo, p<0.05), but no difference in survival was observed based on alpha-tocopherol levels. Twenty-two patients had evaluation of retinol, alpha-tocopherol and C-reactive protein at least once during the follow up. Serum concentration of alpha-tocopherol decreased significantly during the therapy, but retinol and C-reactive protein concentrations remained unchanged. In conclusion, a significant correlation was observed between serum retinol and C-reactive protein. Serum alpha-tocopherol decreased significantly during the first month of combination therapy with cetuximab. Low retinol and high C-reactive protein concentrations were predictive of poor prognosis in this patient population.

Linearity and stability of intravenous busulfan pharmacokinetics and the role of glutathione in busulfan elimination

High-dose busulfan (Bu) is frequently used in preparative myeloablative conditioning (MAC) regimens for patients undergoing hematopoietic stem cell transplantation (HSCT). MAC and reduced-intensity conditioning (RIC) protocols for i.v. Bu infusion have been developed to achieve reliable systemic exposure while minimizing toxicity and treatment failure (relapse). The objectives of the present study were to (1) compare the pharmacokinetics (PK) of i.v. Bu in different dosing protocols, (2) compare intrasubject variability of Bu PK over repeated administrations; (3) examine the effect of concomitant administration of fludarabine on Bu PK, and (4) examine the effect of plasma concentrations of glutathione (GSH), the cosubstrate in Bu metabolism, on Bu clearance. We studied Bu PK twice in each of 46 HSCT patients (after the first and then after the middle dose of the treatment cycle) receiving one of 4 dosing protocols, 2 MAC (cumulative dose, 12.8 mg/kg) and 2 RIC (cumulative dose, 6.4 mg/kg), with daily doses administered either as an individual infusion (3.2 mg/kg) or as 4 infusions of 0.8 mg/kg each. Blood samples were obtained for 6-24 hours after dosing for measurement of Bu plasma concentrations. PK parameters were estimated using compartmental analyses. In a subgroup of patients (n = 14), GSH blood concentrations were determined before Bu administration. Dose- and weight-corrected Bu PK parameters (clearance, 0.173 ± 0.051 L/hour · kg; volume of distribution, 0.71 ± 0.17 L/kg; half-life time, 3.0 ± 0.7 hours) did not differ among treatment protocols (all P >.14) and remained stable between the first and mid-cycle doses. Fludarabine did not affect Bu PK. Blood GSH concentrations before Bu dosing were positively correlated with Bu clearance (adjusted R(2) = 0.45; P = .009). Our data indicate that Bu PK parameters are linear, stable, and predictable in different i.v. protocols and are unaffected by coadministration of fludarabine. Differences in whole blood GSH might contribute to variability in Bu clearance.

Oxidation of plasma cysteine/cystine and GSH/GSSG redox potentials by acetaminophen and sulfur amino acid insufficiency in humans

Variations in plasma sulfur amino acid (SAA) pools are associated with disease risks, but little information is available about the factors affecting plasma SAA pools. Drug metabolism by glutathione (GSH) and sulfate conjugation can, in principle, represent a quantitatively important burden on SAA supply. The present study was designed to determine whether therapeutic doses of acetaminophen (APAP) alter SAA metabolism in healthy human adults. A double-blind, crossover design incorporating four treatment periods with diets providing 100% of the recommended dietary allowance (RDA) for SAA without or with APAP (15 mg/kg) and 0% RDA for SAA without or with APAP, in randomized order. After a 3-day equilibration period, chemically defined diets with 100 or 0% RDA for SAA were given for 2 complete days. On day 3, APAP or placebo was given in two successive doses (6-h interval), and timed plasma samples were collected. With SAA intake at 100% RDA, APAP administration oxidized the plasma cysteine/cystine redox potential (E(h)CySS) but not the plasma GSH/GSSG redox potential (E(h)GSSG). The extent of oxidation caused by APAP was similar to that seen with 0% SAA and no APAP. However, APAP administration with 0% SAA did not cause further oxidation beyond APAP or 0% SAA alone. In contrast, an oxidation of the plasma E(h)GSSG was apparent for SAA insufficiency only with APAP. The results suggest a need to evaluate possible effects of APAP in association with SAA insufficiency as a contributing factor in disease risk.

Dietary sulfur amino acid effects on fasting plasma cysteine/cystine redox potential in humans

OBJECTIVE

Oxidation of plasma cysteine/cystine (Cys/CySS) redox potential (E(h)CySS) has been associated with risk factors for cardiovascular disease in humans. Cys and CySS are derived from dietary sulfur amino acids (SAA), but the specific effects of SAA depletion and repletion on Cys/CySS redox indices are unknown. The present study examined the effect of dietary SAA intake level on free Cys, free CySS, and E(h)CySS in human plasma under fasting conditions.

METHODS

Healthy individuals aged 18-36 y (n = 13) were equilibrated to foods providing the RDA for SAA and then fed chemically defined diets without SAA (0 mg · kg(-1) · d(-1); n = 13) followed by SAA at levels approximating the mean (56 mg · kg(-1) · d(-1); n = 8) or 99th percentile (117 mg · kg(-1) · d(-1); n = 5) intake levels of Americans. Fasting plasma samples were collected daily during 4-d study periods and analyzed for free Cys, free CySS, and the E(h)CySS.

RESULTS

The SAA-free diet significantly (P < 0.05) decreased plasma-free Cys concentrations and oxidized E(h)CySS values after 4 d of SAA depletion. With SAA repletion at 56 mg · kg(-1) · d(-1), plasma-free Cys increased significantly and values for E(h)CySS became more reduced. Administration of a diet providing a higher dose of SAA (117 mg · kg(-1) · d(-1)) resulted in a significantly higher level of free Cys and a more reduced E(h)CySS.

CONCLUSIONS

These results show that free Cys and Cys/CySS redox potential (E(h)CySS) in fasting plasma are affected by dietary SAA intake level in humans. Significant changes occur slowly over 4 d with insufficient SAA intake, but rapidly (after 1 d) with repletion.

Postprandial cysteine/cystine redox potential in human plasma varies with meal content of sulfur amino acids

Few data are available on plasma redox responses to sulfur amino acid (SAA) loads. In this study, we had 2 aims: to determine whether the SAA content of a meal affected postprandial plasma cysteine (Cys), cystine (CySS), or redox potential (E(h)CySS) in humans and whether SAA intake level (adequate or inadequate) in the days preceding the meal challenge affected these postprandial levels. Eight healthy individuals aged 18-36 y were equilibrated for 3 d to adequate SAA, fed chemically defined meals without SAA for 5 d (inadequate SAA) and then fed isoenergetic, isonitrogenous meals with adequate SAA for 5 d. On the first and last days with the chemically defined meals, a morning meal containing 60% of the daily food intake was given, and plasma Cys, CySS, and E(h)CySS were determined over an 8-h postprandial time course. Following equilibration to adequate intake, provision of the meal with SAA resulted in increased plasma Cys and CySS concentrations and more reduced plasma E(h)CySS compared with the postprandial values following the same meal without SAA. Equilibration to inadequate SAA intake for the days preceding the meal challenge did not affect this response. The magnitude of the difference in postprandial plasma E(h)CySS (10 mV) due to meal content of SAA was comparable to those which alter physiologic signaling and/or are associated with disease risk. Consequently, the SAA content of meals could affect physiologic signaling and associated disease mechanisms in the postprandial period by changes in Cys, CySS, or E(h)CySS.