Metabolites of 5-fluorouracil, alpha-fluoro-beta-alanine and fluoroacetic acid, directly injure myelinated fibers in tissue culture

Toxic effects of commercial grade indoxacarb and endosulfan on Gammarus kischineffensis (Schellenberg, 1937) (Crustacea: Amphipoda)

This study was designed to investigate the toxic effects of two frequently used commercial insecticides containing endosulfan and indoxacarb on a freshwater amphipod Gammarus kischineffensis. In this context, the 24, 48, 72 and 96 h LC50 values of these pesticides were determined for G. kischineffensis. Then the histopathological effects of these pesticides on the gill tissues of this species were evaluated. At the end of the study, the 96 h LC50 values of commercial-grade endosulfan and indoxacarb for G. kischineffensis were determined as 1.861 μg L-1 and 20.212 mg L-1, respectively. Histopathologically, the most common histopathological alterations in individuals exposed to sublethal concentrations of commercial-grade endosulfan and indoxacarb were pillar cell hypertrophy resulting in atrophy of the hemocoelic space and hemocytic infiltration. Considering these results, it can be said that commercial-grade endosulfan is extremely and indoxacarb is slightly toxic to G. kischineffensis.

Physiological and cognitive changes after treatments of cyclophosphamide, methotrexate, and fluorouracil: implications of the gut microbiome and depressive-like behavior

Introduction

Chemotherapy-induced cognitive impairment colloquially referred to as chemobrain is a poorly understood phenomenon affecting a highly variable proportion of patients with breast cancer. Here we investigate the association between anxiety and despair-like behaviors in mice treated with cyclophosphamide, methotrexate, and fluorouracil (CMF) along with host histological, proteomic, gene expression, and gut microbial responses.

Methods

Forced swim and sociability tests were used to evaluate depression and despair-like behaviors. The tandem mass tag (TMT) proteomics approach was used to assess changes in the neural protein network of the amygdala and hippocampus. The composition of gut microbiota was assessed through 16S rRNA gene sequencing. Finally, quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to evaluate changes in intestinal gap junction markers.

Results and discussion

We observed that CMF induced social and despair-like behavior in mice 96 hours following treatment. Proteomic analysis identified changes in various proteins related to progressive neurological disease, working memory deficit, primary anxiety disorder, and gene expression revealing increases in NMDA and AMPA receptors in both the hippocampus and the amygdala because of CMF treatment. These changes finally, we observed immediate changes in the microbial population after chemotherapy treatment, with a notable abundance of Muribaculaceae and Romboutsia which may contribute to changes seen in the gut.

Versatile use of Carmofur: A comprehensive review of its chemistry and pharmacology

Carmofur, 1-hexylcarbamoyl-5-fluorouracil (HCFU) is an antineoplastic drug, which has been in clinics in Japan since 1981 for the treatment of colorectal cancer. Subsequently, it was also introduced in China, Korea, and Finland. Besides colorectal cancer, it has also shown antitumor activity in other cancers such as breast, head and neck, pancreatic, gastrointestinal, and solid brain tumors. A prodrug of 5-fluorouracil (5-FU), carmofur has shown better gastrointestinal stability and superior antiproliferative activity compared to its active counterpart 5-FU. Recently, carmofur has gained attention as an acid ceramidase inhibitor and as a potential lead compound against several noncancerous diseases such as coronavirus disease 2019, Krabbe disease, acute lung injury, Parkinson's disease, dementia, childhood ependymoma etc. Carmofur has also been reported to have antifungal, and antimicrobial properties. Nevertheless, no comprehensive review is available on this drug. Herein, we summarized the chemistry, pharmacokinetics, and pharmacology of carmofur based on the literature published between January 1976 and March 2022 as identified from PubMed and Google Scholar search engines.

The histopathological, cytopathological and ultrastructural effects of carbaryl on gills of Oreochromis niloticus (Linnaeus, 1758)

Ultrastructural and histopathological reponses in the organs of living organisms are important and useful tools to determine the health condition and the effects of pollutants, such as pesticides, on the organisms. The aim of this study is to determine possible histopathological, cytopathological and ultrastructural alterations in gills of Oreochromis niloticus individuals exposed to 850 μg/L carbaryl standart at 7th, 14th and 21st days with light and electron microscopes. The fish were exposed to carbaryl for 21 days and the histopatological, ultrastructural and cytopathological alterations occuring in the gill tissues of organisms were determined by light, Scanning and Transmission Electron Microscopes (SEM and TEM). At the end of the study, it was observed that carbaryl caused both histopathological and cytopathological changes in the gills of O. niloticus. It has been determined that the most of the pathological changes in the exposed organisms are the metabolic defence reactions.

Acute Toxic Leukoencephalopathy: Etiologies, Imaging Findings, and Outcomes in 101 Patients

BACKGROUND AND PURPOSE

Prior studies regarding acute toxic leukoencephalopathy (ATL) are either small, or preliminary. Our aim was to evaluate etiologies of and differences in imaging severity and outcomes among various etiologies of ATL.

MATERIALS AND METHODS

MRIs of patients with suspected ATL over 15 years were retrospectively reviewed; inclusion criteria were: MRI <3 weeks of presentation with both DWI and FLAIR. These were jointly graded by two neuroradiologists via a previously described score of severity. Clinical outcome was evaluated via both modified Rankin (mRS) and ATL outcome (ATLOS) scores, each being correlated with the DWI and FLAIR scores. Etiologic subgroups of n > 6 patients were statistically compared.

RESULTS

Of 101 included patients, the 4 subgroups of n > 6 were the following: chemotherapy (n = 35), opiates (n = 19), acute hepatic encephalopathy (n = 14), and immunosuppressants (n = 11). Other causes (n = 22 total) notably included carbon monoxide (n = 3) metronidazole (n = 2), and uremia (n = 1). The mean DWI/FLAIR severity scores were 2.6/2.3, 3.3/3.3, 2.1/2.1 and 2.0/2.5 for chemotherapeutics, opiates, AHE and immunosuppressants, respectively, with significant differences in both imaging severity and outcome (P = .003-.032) among subgroups, particularly immunosuppressant versus chemotherapy-related ATL and immunosuppressants versus opiates (P = .004-.032) related ATL. DWI and FLAIR severity weakly correlated with outcome (ρ = 0.289-.349, P < .005) but correlated stronger in the chemotherapy (ρ = 0.460-.586, P < .010) and opiate (ρ =.472-.608, P < .05) subgroups, which had the worst outcomes. ATL clinically resolved in 36%, with severe outcomes in 23% (coma or death, 9/16 deaths from fludarabine). Notable laboratory results were elevated CSF myelin basic protein levels in 8/9 patients and serum blood urea nitrogen levels in 24/91.

CONCLUSIONS

Clinical outcomes of ATL vary on the basis of etiology, being worse in chemotherapeutic- and opiate-related ATL. Uremia may be a predisposing or exacerbating factor.

A direct, sensitive and efficient method for determination of alpha-fluoro-beta-alanine in urine: Evaluating the influence of magnesium isoglycyrrhizinate on excretion in rat model

Alpha-fluoro-beta-alanine (FBAL), the final metabolite of capecitabine, is a toxic compound excreting with urine. Magnesium isoglycyrrhizinate injection is a traditional Chinese medicine prescribed with capecitabine as a hepatoprotective agent. The purposes of this study are to develop an ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method for direct, efficient and sensitive determination of FBAL in urine and explore the influence of magnesium isoglycyrrhizinate on the excretion of FBAL in rat model. The method development and validation were successfully achieved. The run time was 3 min based on an HILIC column and linear range was 0.02-10.00 μg/mL. The mass detection was completed using electrospray ionization in positive ionization mode with a multiple reaction monitoring mode. A simplified sample pretreatment procedure was performed by direct dilution using 50% acetonitrile aqueous solution with the matrix effect range 48.98%-52.10% and the recovery range 78.68%-83.28%. The intra-day and inter-day precision and accuracy were <11% and within ±6%, and the stability, specificity, carry-over, dilution effect and linearity all conformed to the criterions. This study presented preliminary results that the influence of magnesium isoglycyrrhizinate on the excretion of FBAL was insignificant in rats based on this new developed method.

Magnetic resonance imaging patterns of treatment-related toxicity in the pediatric brain: an update and review of the literature

Treatment-related neurotoxicity is a potentially life-threatening clinical condition that can represent a diagnostic challenge. Differentiating diagnoses between therapy-associated brain injury and recurrent disease can be difficult, and the immediate recognition of neurotoxicity is crucial to providing correct therapeutic management, ensuring damage reversibility. For these purposes, the knowledge of clinical timing and specific treatment protocols is extremely important for interpreting MRI patterns. Neuroradiologic findings are heterogeneous and sometimes overlapping, representing the compounding effect of the different treatments. Moreover, MRI patterns can be acute, subacute or delayed and involve different brain regions, depending on (1) the mechanism of action of the specific medication and (2) which brain regions are selectively vulnerable to specific toxic effects. This review illustrates the most common radiologic appearance of radiotherapy, chemotherapy and medication-associated brain injury in children, with special focus on the application of advanced MRI techniques (diffusion, perfusion and proton spectroscopy) in the diagnosis of the underlying processes leading to brain toxicity.

Transport of haloacids across biological membranes

Haloacids are considered to be environmental pollutants, but some of them have also been tested in clinical research. The way that haloacids are transported across biological membranes is important for both biodegradation and drug delivery purposes. In this review, we will first summarize putative haloacids transporters and the information about haloacids transport when studying carboxylates transporters. We will then introduce MCT1 and SLC5A8, which are respective transporter for antitumor agent 3-bromopyruvic acid and dichloroacetic acid, and monochloroacetic acid transporters Deh4p and Dehp2 from a haloacids-degrading bacterium. Phylogenetic analysis of these haloacids transporters and other monocarboxylate transporters reveals their evolutionary relationships. Haloacids transporters are not studied to the extent that they deserve compared with their great application potentials, thus future inter-discipline research are desired to better characterize their transport mechanisms for potential applications in both environmental and clinical fields.

Diffusion-weighted MRI in neuro-oncology

Diffusion-weighted MRI (DW-MRI) provides image contrast dependent on the molecular movement of water. It has been most widely used in the diagnosis of cytotoxic edema secondary to acute cerebral ischemia, but has also proven useful in assessing tumor cellularity and grade, abscess formation, cysts and various forms of white matter disorders. Furthermore, DW-MRI is used to generate maps of subcortical white matter tracts and their relationship to structural brain lesions that may serve for preoperative planning and intraoperative guidance. We provide a comprehensive review of current practical applications of DW-MRI in the diagnosis and treatment of primary brain tumors, metastases and nonmetastatic neurologic complications of cancer. A detailed description of diffusion tensor imaging is beyond the scope of this review. We performed a comprehensive search of the PubMed database of the USA National Library of Medicine with use of various combinations of the following search terms: diffusion-weighted imaging, apparent diffusion coefficient, diffusion tensor imaging, diffusion tensor, brain, tumor, glioblastoma, lymphoma, primary CNS lymphoma, stroke, cancer, abscess, leukoencephalopathy, methotrexate, fluorouracil, capecitabine. We identified original articles and well-documented case reports of DW-MRI applications in patients with primary brain neoplasms, metastases and nonmetastatic neurologic complications that we judged to be of high impact on the field. We largely selected publications from the past 10 years, but did not exclude commonly referenced and highly regarded older publications. We also searched the reference lists of articles identified by this search strategy and selected those we judged relevant. Review articles are cited to provide readers with more details and more references than can be covered here.

Chemotherapy-related cognitive dysfunction: current animal studies and future directions

Cognitive impairment is a potential long-term side effect of adjuvant chemotherapy that can have a major impact on the quality of life of cancer survivors. There is a growing number of preclinical studies addressing this issue, thereby extending our knowledge of the mechanisms underlying chemotherapy-induced neurotoxicity. In this review, we will summarize the recent advances and important findings presented in these studies. Emerging challenges, such as the development of neuroprotective strategies, and the role of the blood-brain barrier on cognitive impairment will be described and future directions in this field of investigation will be outlined.

Methotrexate induced leucoencephalopathy: A stroke mimic

With increasing usage of thrombolysis in the treatment of acute ischemic strokes within 4.5- hour window, it is becoming more important to recognize stroke mimics. Though the incidence of stroke mimics being thrombolysed is less than 3%, it is essential to diagnose them so as to avoid wrong thrombolytic treatment which carries potential complications of bleeding. We describe the case of a 17 year old girl with acute lymphoblastic leukemia, who developed stroke like episodes on two consecutive challenges with a chemotherapeutic regime which included intravenous and intrathecal methotrexate. She had MRI changes consistent with acute ischemic stroke on both occasions. Her deficits recovered completely and spontaneously, as did the MRI changes. She did not have any further episodes when methotrexate was excluded from the chemotherapeutic regime.

[Management of chemotherapy in hemodialysis patients]

BACKGROUND

The increased incidence of cancer in dialysis patients has been discussed since the mid-70s. Consequently, oncologists, nephrologists and pharmacists are increasingly facing challenging situations of cytotoxic drug handling in dialysis patients. In dialysis patients, two main issues must be considered. First, renal function of hemodialysis (HD) patients is no longer functional. Therefore, these patients may necessitate drug dosage reduction, namely drug prescription, must be cautiously checked before administration with appropriate dosage adjustment whenever necessary to ensure efficacy while avoiding overdosage and related side effects. Secondly, drug clearance by dialysis must be taken into account for appropriate chemotherapy timing in order to avoid drug removal, which may result in a loss of efficacy.

METHODS

We reviewed the international literature on the pharmacokinetics, efficacy, tolerance and dosage adjustment of anticancer drugs used on hemodialysis cancer patients, using the key words: kidney, renal, dialysis, hemodialysis, end-stage renal disease and the name of each drug.

RESULTS

Only case reports and small series were found. 57.1% of the drugs need dosage adjustment and 64.3% should be administered after the dialysis session.

CONCLUSION

Cancer treatment in feasible in dialysis patients. Some drugs require dosage adaptation while others can be given as in patients with normal kidney function. These patients need coordinated care between oncologists, nephrologists and pharmacists to optimize drug delivery and logistics. Frailty scores, like in oncogeriatrics, should be built to optimally adapt cancer treatments in these dialysis patients.

Development and utilization of a combined LC-UV and LC-MS/MS method for the simultaneous analysis of tegafur and 5-fluorouracil in human plasma to support a phase I clinical study of oral UFT®/leucovorin

Tegafur is a 5-fluorouracil (5-FU) prodrug widely used outside the United States to treat colorectal cancer as well as cancers of the head and neck. The resulting plasma concentrations of tegafur are much higher than those of 5-FU; thus, analytical methods are needed that are sensitive enough to detect low plasma concentrations of 5-FU and robust enough to simultaneously analyze tegafur. Previous LC-MS/MS methods have either failed to demonstrate the ability to simultaneously measure low 5-FU and high tegafur plasma levels, or failed to be applicable in clinical studies. Our goal was to develop a method capable of measuring low concentrations of 5-FU (8-200 ng/ml) and high concentrations of tegafur (800-20,000 ng/ml) in human plasma and to subsequently evaluate the utility of the method in patient samples collected during a phase I clinical study where oral doses of either 200mg or 300 mg UF®/LV (uracil and tegafur in a 4:1 molar ratio plus leucovorin) were administered. A combined LC-MS/MS and LC-UV method was developed utilizing negative ion atmospheric pressure ionization (API). The method provides an accuracy and precision of <10% and <6%, respectively, for both analytes. Material recoveries from the liquid-liquid extraction technique were 97-110% and 86-91% for tegafur and 5-FU, respectively. Utilization of this method to determine tegafur and 5-FU plasma concentrations followed by noncompartmental pharmacokinetic analyses successfully estimated pharmacokinetic parameters (C(MAX), t(MAX) and AUC(0-10h)) in the clinical study patients. Overall, this method is ideal for the simultaneous bioanalysis of low levels of 5-FU and relatively higher levels of its prodrug, tegafur, in human plasma for clinical pharmacokinetic analysis.

Medication neurotoxicity in children

Medication neurotoxicity may have a variety of imaging manifestations in children. In this pictorial essay, we review the two most common brain injury patterns, posterior reversible encephalopathy syndrome (PRES) and acute toxic leukoencephalopathy (ATL). Proposed etiologies, salient features on neurological imaging, and methods for differentiating these entities and their implications will be discussed. Certain agents do not fall into these two broad patterns but instead characteristically involve central structures. We individually review several medications and their respective neurotoxic appearances including methotrexate, cyclosporine A, tacrolimus, metronidazole and vigabatrin. Diagnosis of medication neurotoxicity may be achieved by the combination of new-onset neurological deficits, recent initiation of a new therapy agent and distinctive findings on magnetic resonance imaging. Clinical and radiological improvement and/or resolution are frequently observed after the agent is discontinued.

Acute and late onset cognitive dysfunction associated with chemotherapy in women with breast cancer

BACKGROUND

Growing evidence supports cognitive dysfunction associated with standard dose chemotherapy in breast cancer survivors. We determined the incidence, nature, and chronicity of cognitive dysfunction in a prospective longitudinal randomized phase 3 treatment trial for patients with T1-3, N0-1, M0 breast cancer receiving 5-fluorouracil, doxorubicin, and cyclophosphamide with or without paclitaxel.

METHODS

Forty-two patients underwent a neuropsychological evaluation including measures of cognition, mood, and quality of life. Patients were scheduled to be assessed before chemotherapy, during and shortly after chemotherapy, and 1 year after completion of chemotherapy.

RESULTS

Before chemotherapy, 21% (9 of 42) evidenced cognitive dysfunction. In the acute interval, 65% (24 of 37) demonstrated cognitive decline. At the long-term evaluation, 61% (17 of 28) evidenced cognitive decline after cessation of treatment. Within this group of patients, 71% (12 of 17) evidenced continuous decline from the acute interval, and, notably, 29% (5 of 17) evidenced new delayed cognitive decline. Cognitive decline was most common in the domains of learning and memory, executive function, and processing speed. Cognitive decline was not associated with mood or other measured clinical or demographic characteristics, but late decline may be associated with baseline level of performance.

CONCLUSIONS

Standard dose systemic chemotherapy is associated with decline in cognitive function during and shortly after completion of chemotherapy. In addition, delayed cognitive dysfunction occurred in a large proportion of patients. These findings are consistent with a developing body of translational animal research demonstrating both acute and delayed structural brain changes as well as functional changes associated with common chemotherapeutic agents such as 5-fluorouracil.

Hyperperfusion on magnetic resonance imaging in acute chemotherapy-related leukoencephalopathy

Acute chemotherapy-related leukoencephalopathy can present similar to acute stroke with symptoms including aphasia, dysarthria, and hemiplegia. Differentiation based on clinical appearance is challenging, and physicians must distinguish between the 2 conditions rapidly to institute appropriate therapies. An 8-year-old male with acute lymphoblastic leukemia receiving chemotherapy, including intrathecal methotrexate, presented to our emergency center with 2 hours of expressive aphasia and flaccid right hemiplegia. Emergent magnetic resonance imaging (MRI) was obtained, demonstrating diffusion restriction within bilateral corona radiata and centrum semiovale. Magnetic resonance perfusion revealed mildly increased perfusion, a finding inconsistent with ischemic stroke and previously unreported in acute chemotherapy-related leukoencephalopathy without necrosis. This increased perfusion conclusively eliminated stroke from the clinical differential. Magnetic resonance perfusion imaging proved valuable to rapidly distinguish acute chemotherapy-related leukoencephalopathy from ischemia, and the evaluation of perfusion alterations in this disorder may provide further insight into the pathophysiology of this entity.

Acute toxic leukoencephalopathy: potential for reversibility clinically and on MRI with diffusion-weighted and FLAIR imaging

OBJECTIVE

Toxic leukoencephalopathy may present acutely or subacutely with symmetrically reduced diffusion in the periventricular and supraventricular white matter, hereafter referred to as periventricular white matter. This entity may reverse both on imaging and clinically. However, a gathering together of the heterogeneous causes of this disorder as seen on MRI with diffusion-weighted imaging (DWI) and an analysis of their likelihood to reverse has not yet been performed. Our goals were to gather causes of acute or subacute toxic leukoencephalopathy that can present with reduced diffusion of periventricular white matter in order to promote recognition of this entity, to evaluate whether DWI with apparent diffusion coefficient (ADC) values can predict the extent of chronic FLAIR abnormality (imaging reversibility), and to evaluate whether DWI can predict the clinical outcome (clinical reversibility).

MATERIALS AND METHODS

Two neuroradiologists retrospectively reviewed the MRI examinations of 39 patients with acute symptoms and reduced diffusion of periventricular white matter. The reviewers then scored the extent of abnormality on DWI and FLAIR. ADC ratios of affected white matter versus the unaffected periventricular white matter were obtained. Each patient's clinical records were reviewed to determine the cause and clinical outcome. Histology findings were available in three patients. Correlations were calculated between the initial MRI markers and both the clinical course and the follow-up extent on FLAIR using Spearman's correlation coefficient.

RESULTS

Of the initial 39 patients, seven were excluded because of a nontoxic cause (hypoxic-ischemic encephalopathy [HIE] or congenital genetic disorders) or because of technical errors. In the remaining 32 patients, no correlation was noted between any of the initial MRI markers (percentage of ADC reduction, DWI extent, or FLAIR extent) with the clinical outcome. Three patients had histologic correlation. However, moderate correlation was seen between the extent of abnormality on initial FLAIR and the extent on follow-up FLAIR (r = 0.441, p = 0.047). Of the 13 patients who underwent repeat MRI at 21 days or longer, the reduced diffusion resolved in all but one. Significant differences were noted between ADC values in affected white matter versus unaffected periventricular white matter on initial (p < 0.0001) but not on follow-up MRI (p = 0.13), and in affected white matter on initial versus follow-up (p = 0.0014) in those individuals who underwent repeat imaging on the same magnet (n = 9), confirming resolution of the DWI abnormalities.

CONCLUSION

Acute toxic leukoencephalopathy with reduced diffusion may be clinically reversible and radiologically reversible on DWI, and may also be reversible, but to a lesser degree, on FLAIR MRI. None of the imaging markers measured in this study appears to correlate with clinical outcome, which underscores the necessity for prompt recognition of this entity. Alerting the clinician to this potentially reversible syndrome can facilitate treatment and removal of the offending agent in the early stages.

Systemic 5-fluorouracil treatment causes a syndrome of delayed myelin destruction in the central nervous system

BACKGROUND

Cancer treatment with a variety of chemotherapeutic agents often is associated with delayed adverse neurological consequences. Despite their clinical importance, almost nothing is known about the basis for such effects. It is not even known whether the occurrence of delayed adverse effects requires exposure to multiple chemotherapeutic agents, the presence of both chemotherapeutic agents and the body's own response to cancer, prolonged damage to the blood-brain barrier, inflammation or other such changes. Nor are there any animal models that could enable the study of this important problem.

RESULTS

We found that clinically relevant concentrations of 5-fluorouracil (5-FU; a widely used chemotherapeutic agent) were toxic for both central nervous system (CNS) progenitor cells and non-dividing oligodendrocytes in vitro and in vivo. Short-term systemic administration of 5-FU caused both acute CNS damage and a syndrome of progressively worsening delayed damage to myelinated tracts of the CNS associated with altered transcriptional regulation in oligodendrocytes and extensive myelin pathology. Functional analysis also provided the first demonstration of delayed effects of chemotherapy on the latency of impulse conduction in the auditory system, offering the possibility of non-invasive analysis of myelin damage associated with cancer treatment.

CONCLUSIONS

Our studies demonstrate that systemic treatment with a single chemotherapeutic agent, 5-FU, is sufficient to cause a syndrome of delayed CNS damage and provide the first animal model of delayed damage to white-matter tracts of individuals treated with systemic chemotherapy. Unlike that caused by local irradiation, the degeneration caused by 5-FU treatment did not correlate with either chronic inflammation or extensive vascular damage and appears to represent a new class of delayed degenerative damage in the CNS.

Candidate mechanisms for capecitabine-related hand-foot syndrome

AIMS

The oral fluoropyrimidine prodrug capecitabine is widely used in oncology. Capecitabine was designed to generate 5FU via the thymidine phosphorylase (TP) enzyme, preferentially expressed in tumoral tissues. Hand-foot syndrome (HFS) is a limiting toxicity of capecitabine. A pilot study on healthy volunteers was conducted in order to test the hypothesis that the occurrence of HFS could be related to tissue-specific expression of drug-metabolizing enzymes in the skin of the palm and sole. To this end, the expression of TP (activating pathway), dihydropyrimidine dehydrogenase (DPD, catabolic pathway) and cell proliferation (Ki67) were measured in the skin of the palm (target tissue for HFS) and of the lower back (control area).

METHODS

Two paired 4-mm diameter punch biopsy specimens (palm and back) were taken in 12 healthy volunteers. Immunohistochemical analyses were performed on frozen tissues.

RESULTS

Proliferation rate (Ki67 staining) was significantly higher in epidermal basal cells of the palm compared with the back (P = 0.008). Also, TP and DPD expression were significantly greater in the palm relative to the back (P = 0.039 and 0.012, respectively). TP and Ki67 expression were positively and significantly correlated in the palm.

CONCLUSIONS

The high proliferation rate of epidermal basal cells in the palm could make them more sensitive to the local action of cytotoxic drugs. TP-facilitated local production of 5FU in the palm during capecitabine treatment could explain the occurrence of HFS. This observation may support future strategies to limit the occurrence of HFS during capecitabine therapy.

Use of Capecitabine to Prevent Acute Renal Allograft Rejection in Dog Erythrocyte Antigen-Mismatched Mongrel Dogs

OBJECTIVE

To assess efficacy and toxicity of a capecitabine (CAP)-based regimen for preventing rejection of renal allografts in dog erythrocyte antigen (DEA)-mismatched mongrel dogs.

STUDY DESIGN

Prospective, pilot study.

ANIMALS

Eight healthy, unrelated, DEA mismatched, adult mongrel dogs.

METHODS

All dogs received CAP, starting at 50 mg/m2 PO b.i.d. 4 days preoperatively, increasing to 200 mg/m2 PO b.i.d. by the day of surgery. All dogs received cyclosporine-A (CsA) and prednisolone starting 2 days preoperatively. Standard heterotopic renal transplantation with native nephrectomy was performed. After 90 days, surviving dogs were euthanatized and histopathologic examination was performed.

RESULTS

Two of 8 dogs developed acute neurotoxicity leading to death or euthanasia within 5 days of surgery. For the 6 remaining dogs, there were no statistically significant changes in complete blood count or serum biochemical values. No opportunistic infections developed during the study period. Five of 6 dogs had no to minimal evidence of graft rejection. Two of 6 dogs developed superficial and pigmentary keratitis. Significant histopathologic findings in all dogs included mild lymphoplasmacytic gastroenteritis, steroid hepatopathy, and corneal epithelial thinning. One dog had moderate interstitial nephritis and pyelitis.

CONCLUSIONS

In this experimental model, a CAP-CsA-prednisolone immunosuppressive regimen was effective in preventing rejection of allografts in DEA-mismatched dogs. Severe, unpredictable neurotoxicity and variable ocular toxicity significantly limit clinical applications at this time.

CLINICAL RELEVANCE

A CAP-CsA-prednisolone protocol is an effective, oral immunosuppressive regimen for prevention of allograft rejection in DEA-mismatched mongrel dogs. For clinical application, identification of patients susceptible to toxic side effects would be necessary.

5-Fluorouracil cardiotoxicity induced by alpha-fluoro-beta-alanine

Cardiotoxicity is a rare complication occurring during 5-fluorouracil (5-FU) treatment for malignancies. We herein report the case of a 70-year-old man with 5-FU-induced cardiotoxicity, in whom a high serum level of alpha-fluoro-beta-alanine (FBAL) was observed. The patient, who had unresectable colon cancer metastases to the liver and lung, was referred to us for chemotherapy from an affiliated hospital; he had no cardiac history. After admission, the patient received a continuous intravenous infusion of 5-FU (1000 mg/day), during which precordial pain with right bundle branch block occurred concomitantly with a high serum FBAL concentration of 1955 ng/ml. Both the precordial pain and the electrocardiographic changes disappeared spontaneously after the discontinuation of 5-FU. As the precordial pain in this patient was considered to have been due to 5-FU-induced cardiotoxicity, the administration of 5-FU was abandoned. Instead, oral administration of S-1 (a derivative of 5-FU), at 200 mg/day twice a week, was instituted, because S-1 has a strong inhibitory effect on dihydropyrimidine dehydrogenase, which catalyzes the degradative of 5-FU into FBAL. The serum FBAL concentration subsequently decreased to 352 ng/ml, the same as the value measured on the first day of S-1 administration. Thereafter, no cardiac symptoms were observed. The patient achieved a partial response 6 months after the initiation of the S-1 treatment. The experience of this case, together with a review of the literature, suggests that FBAL is related to 5-FU-induced cardiotoxicity. S-1 may be administered safely to patients with 5-FU-induced cardiotoxicity.

Reversible Impairment of Auditory Callosal Pathway in 5-Fluorouracil-Induced Leukoencephalopathy

OBJECTIVE

To report the course of functional and imaging recovery of the auditory callosal pathway in a patient with 5-fluorouracil-induced leukoencephalopathy.

DESIGN

Case study.

SETTING

University hospital.

PATIENT

A 58-year-old man with hypopharyngeal cancer who developed 5-fluorouracil-induced leukoencephalopathy.

MAIN OUTCOME MEASURES

Imaging (magnetic resonance imaging) and functional (dichotic listening test) evaluation on the auditory callosal pathway.

RESULTS

The patient underwent systemic chemotherapy with pirarubicin, cisplatin, and 5-fluorouracil. On the last day of the regimen, the patient suddenly became restless and convulsive. On diffusion-weighted magnetic resonance images, the signal intensity at the splenium of the corpus callosum was very high. Fluid-attenuated inversion recovery images showed no abnormal findings at this time. Intravenous methylprednisolone sodium succinate and glycerin 10% was started immediately. On the ninth day after onset, the patient was free of neurologic symptoms. Although pure-tone audiograms and speech discrimination scores were normal, dichotic listening tests revealed significant left ear suppression, indicating severe injury of the auditory callosal pathway. On fluid-attenuated inversion recovery images, the signal intensity at the splenium was high, whereas the posterior trunk was normal. At 6 weeks after onset, dichotic listening test results returned to normal and hyperintensity at the splenium was much less marked on fluid-attenuated inversion recovery images.

CONCLUSION

By using both functional and imaging modalities, this case study demonstrated, for the first time in a reversible manner, that the auditory callosal pathway runs through the most posterior part of the corpus callosum including the splenium. Diffusion-weighted magnetic resonance imaging was considered useful for early diagnosis of 5-fluorouracil-induced leukoencephalopathy.

Reversible findings of restricted diffusion in 5-flourouracil neurotoxicity

A 35-year-old woman presented with neurotoxicity correlated to an i.v. regimen of 5-fluorouracil as episodes of acute confusional state and abnormalities of symmetrically restricted diffusion in the periventricular white matter and corpus callosum. On discontinuing the medication, the areas of severely restricted diffusion had entirely resolved, with minimal residual T2 signal abnormality. In this case, immediate discontinuation of the chemotherapeutic agent apparently reversed the patient's symptoms and findings on MRI. The scant information available in the published literature regarding this phenomenon is reviewed with regard to 5-fluorouracil.

Local fluorouracil chemotherapy interferes with neural and behavioral recovery after brain tumor-like mass compression

In this study, we investigated the impact of intracerebral delivery of chemotherapy on functional recovery from focal cortical tissue displacement, characteristic of brain tumors. Unilateral focal brain compression was induced by epidural implantation of an inverted hemisphere-shaped bead over the sensorimotor cortex. Microinjections of a total of 1mg chemoagent fluorouracil or the same volume of saline were made into the compressed cortex. Behavioral tests of forelimb sensorimotor function were conducted during 4 weeks' observation. Rats subjected to any of the three types of lesions, saline microinjection plus cortical compression, chemoagent microinjection alone, or chemoagent microinjection combined with cortical compression, demonstrated significant behavioral deficits in several sensorimotor tasks, compared with saline-microinjected control animals. In placing tests, behavioral deficits elicited by each single treatment were worsened by combined treatment with chemoagent microinjection and focal cortical compression. Concurrently, local delivery of chemoagent into the compressed cortex induced increased cortical tissue loss, necrosis and apoptosis. These data indicate that local chemotherapy exacerbates compression-induced neurological impairment, and a model of controlled focal cortical compression may provide a valuable means to improve anti-cancer therapeutic designs with reduced deterioration of brain function.

Use of Capecitabine After Renal Allograft Transplantation in Dog Erythrocyte Antigen-Matched Dogs

OBJECTIVES

To investigate the use of a capecitabine (CAP)-based regimen after renal transplantation in dogs.

STUDY DESIGN

Prospective, pilot study.

ANIMALS

Healthy, unrelated, dog erythrocyte antigen (DEA)-matched, adult beagles.

METHOD

Standard heterotopic renal transplantation with native nephrectomy was performed in 7 dogs. Dogs received oral, twice daily, CAP (250 mg/m2), cyclosporine-A (CsA) (4 mg/kg), ketoconazole (5 mg/kg), and prednisolone (0.25 mg/kg). After 90 days the surviving dogs were euthanatized and complete necropsy was performed.

RESULTS

Seven transplants were performed. All dogs survived surgery. Six dogs had acute neurotoxicity, which resulted in death or euthanasia of 2 dogs within 2 days of surgery. In the remaining dogs, toxicity resolved rapidly with cessation of drug administration. Thereafter, modification of the regimen minimized toxicity. The 5 remaining dogs survived to study end; 4 dogs had no evidence of graft rejection. Necropsy examination was mostly unremarkable in all dogs. There were no major changes in CBC or biochemical values, except for a significant increase in serum calcium.

CONCLUSIONS

CAP appeared well tolerated in most dogs. Toxicity occurred but abated with modification of the drug regimen. Efficacy for postoperative immunosuppression cannot be determined by this study, although results are promising.

CLINICAL RELEVANCE

CAP-CsA-prednisolone is an effective, oral immunosuppressive regimen for prevention of acute allograft rejection in DEA-matched beagles. Further studies on dose, toxicity, and efficacy compared with current immunosuppressive regimens are needed before use in clinical practice.

Lack of contribution of dihydrofluorouracil and alpha-fluoro-beta-alanine to the cytotoxicity of 5'-deoxy-5-fluorouridine on human keratinocytes

Capecitabine (Xeloda) is a very active oral fluoropyrimidine (colon and breast cancers) whose clinical use is complicated by the presence of hand-foot syndrome (HFS). This cutaneous toxicity is less frequently encountered with other oral fluoropyrimidines containing a dihydropyrimidine dehydrogenase (DPD) inhibitor. The HFS is thus attributed to the presence of the main 5-fluorouracil (5-FU) metabolites, dihydrofluorouracil (5-FUH2) and alpha-fluoro-beta-alanine (FBAL), but without strong pharmacological arguments. The aim of the present study was to closely examine this latter hypothesis. Capecitabine generates 5'-deoxyflourouridine (5'-DFUR) which is transformed into 5-FU at the cellular target site through the intermediary of thymidine phosphorylase (TP). The cytotoxic effects (MTT test, 4-day exposure) of 5'-DFUR, 5-FU, 5-FUH2 and FBAL were tested against the spontaneously immortalized human keratinocyte cell line (HaCaT) and the human cancer colon cell line WiDr as a control. Mean IC50s on HaCaT and WiDr were, respectively, 1.3 and 10 microM for 5'-DFUR, 0.2 and 3.3 microM for 5-FU, 13.4 and 560 microM for 5-FUH2, and greater than 650 and 6500 microM for FBAL. The respective 5'-DFUR IC50s values were not different when cells were exposed to 5'-DFUR alone or in combination with 5-FU, 5-FUH2 and FBAL in both cell lines, the relative proportion of each drug reflecting known pharmacokinetic data for capecitabine (5'-DFUR 12.4%, 5-FUH2 6.4%, 5-FU 1.2% and FBAL 80%). This latter finding demonstrates the relative lack of significant cytotoxic activity of 5-FUH2 and FBAL on human keratinocytes. TP activity was particularly high in HaCaT cells and DPD activity was very low in both cell lines. These data strongly suggest that the presence of 5-FU metabolites does not play a major role in the HFS generated by capecitabine and that it can probably be attributed to particularly high TP activity in keratinocytes. This observation may have important clinical consequences such as a possible local pharmacological inhibition of TP for controlling HFS.

Peripheral neuropathy associated with capecitabine

5-fluorouracil (5-FU)-associated peripheral neuropathy is an uncommon event. Capecitabine (CAP) is a pro-drug of 5-FU and peripheral neuropathy associated with CAP has not been reported. During analysis of 28 patients receiving CAP with concomitant radiation (XRT) for pancreatic cancer (resected or locally advanced), two patients developed signs and symptoms consistent with peripheral neuropathy. Patients received CAP 1200-1600 mg/m2 in two divided doses with XRT (total 5040-5400 Gy) x 6 weeks, followed by 4 weeks rest, then 6 cycles of CAP 2000-2500 mg/m2 in two divided doses x 14 days every (q) 3 weeks. Patients were assessed weekly during CAP-XRT and q 3 weeks during CAP alone. Patient A reported right leg weakness (foot drop) during week 4 of CAP-XRT (1600 mg/m2). Patient B developed perioral and upper extremity paresthesias during the fourth cycle of CAP alone (2500 mg/m2). Dihydropyrimidine dehydrogenase (DPD) activity was measured by radioisotopic assay using lysates of peripheral blood mononuclear cells. Neurologic examination revealed right foot drop in Patient A and was unremarkable in Patient B. Central nervous system imaging was negative. Electromyogram and nerve conduction studies showed sensorimotor peripheral neuropathy in both patients. DPD activity was normal in both patients. There was no evidence of disease progression. Neurologic symptoms resolved after stopping CAP for 4 weeks in Patient A, with no recurrence after reinitiating CAP alone at 2000 mg/m2. Patient B continued at 80% of standard dose (2000 mg/m2) and symptoms resolved without further intervention. We conclude peripheral neuropathy with 5-FU is rare. Neurotoxicity occurs most often with intermittent high dose 5-FU as bolus injection or 24- to 48-h infusions. The etiology of neurotoxicity in our two patients remains unclear; however, as CAP is rapidly metabolized to 5-FU in patients with normal liver function, it is likely that 5-FU or its active metabolites (fluoro-beta-alanine) were contributing factors. Knowledge regarding potential adverse effects of CAP is paramount and dose modification is indicated with development of neurotoxicity.

5-fluorouracil-induced oligodendrocyte death and inhibitory effect of cycloheximide, Trolox, and Z-VAD-FMK in murine cortical culture

BACKGROUND

5-fluorouracil (5-FU) is a widely used anticancer drug. One of the adverse effects of this drug is selective cerebral white matter injury, but to the authors' knowledge its mechanism has not been well documented. The current study was performed to investigate the mechanism of cerebral white matter injury caused by 5-FU and to develop the intervention to attenuate its injury in vitro.

METHODS

Mixed oligodendrocyte/astrocyte cells were dissociated from specimens taken from approximately 2-day-old postnatal mouse cortex and cultured for 3-4 weeks. The culture cells were exposed to 5-FU, cycloheximide, emetine, Z-VAD-fmk, 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(F)-quinoxaline (NBQX), Trolox, and epigallocatechin gallate. Oligodendrocyte cell death was assessed by counting the number of viable galactocerebroside-positive cells per x 100 field.

RESULTS

Mixed oligodendrocyte/astrocyte culture cells that were exposed to 5-FU (at doses of 10 microM, 30 microM, and 100 microM) for 24 hours ensued concentration-dependent oligodendrocyte death. The majority of oligodendrocytes, but few astrocytes, were injured by 100 microM 5-FU. Trolox, a vitamin E analog antioxidant, as well as cycloheximide (a protein synthesis inhibitor) and Z-VAD-fmk (a caspase inhibitor), significantly attenuated the 5-FU-induced oligodendrocyte death. However, NBQX, an alpha-amino-2,3-dihydro-5-methyl-3-oxo-4-isoxazolepropionic acid (AMPA) receptor antagonist, did not appear to effect the 5-FU-induced oligodendrocyte death.

CONCLUSIONS

The findings of the current study suggested that 5-FU led to oligodendrocyte death rather than astrocyte death by way of the apoptotic process, whereas antioxidants may prevent the 5-FU-induced oligodendrocyte cell death in vitro.

Diffusion-weighted magnetic resonance imaging in early stage of 5-fluorouracil-induced leukoencephalopathy

We report a case of 5-fluorouracil (5-FU)-induced leukoencephalopathy in which magnetic resonance imaging (MRI) of the brain, including diffusion-weighted imaging (DWI), was performed serially. The initial T2-weighted and FLAIR images showed diffuse mild hyperintensity in bilateral deep cerebral white matter and corpus callosum, which on T1WI appeared as non-enhanced faint hypointensity. Isotropic DWI disclosed the abnormality as well-conspicuous diffuse hyperintensity with decreased ADC. Serial studies revealed that majority of the abnormal signal intensity on these sequences resolved, and the decreased ADC values approached normal. Some hyperintensity remained in the deep cerebral white matter and the splenium, but no further significant ADC change after normalization was noted. Measurement of ADC along the three orthogonal directions showed the presence of directional dependence of diffusion throughout the length of study. These findings suggest that early stage of 5-FU-induced leukoencephalopathy is associated with reversible restricted diffusion and preservation of anisotropy. Diffusion-weighted imaging may be useful for the diagnosis.

Pharmacokinetics of 5-fluorouracil and its catabolites determined by 19F nuclear magnetic resonance spectroscopy for a patient on chronic hemodialysis

5-fluorouracil (5-FU), widely used for chemotherapy of colorectal carcinoma, requires intracellular anabolic conversion to cytotoxic nucleotides and exhibits a narrow therapeutic range with dose-dependent and concentration-dependent effects. 5-FU undergoes extensive metabolic degradation to several catabolites, which are excreted mainly by the kidneys. Alteration of the pharmacokinetics of 5-FU and its catabolites as a result of renal dysfunction might augment systemic toxicity. Because no data are available for patients with severe renal failure, the pharmacokinetic parameters of 5-FU and its catabolites were determined for a patient with colorectal carcinoma and end-stage renal disease on maintenance hemodialysis therapy. Plasma was analyzed by 19F nuclear magnetic resonance spectroscopy for the first 5-day treatment cycle (daily bolus injections of 5-FU for 5 days in combination with low-dose folinic acid). On days 1 and 5, the pharmacokinetic parameters for 5-FU (total area under the plasma concentration-time curve, terminal half-life, total plasma clearance, volume of distribution based on the terminal phase) and its initial catabolite dihydrofluorouracil (total area under the plasma concentration-time curve, terminal half-life) were in the ranges reported in the literature for patients with normal renal function, implying no need for primary dose adjustment. In contrast, the final 5-FU catabolite alpha-fluoro-beta-alanine (FBAL) accumulated to a concentration of 276 micromol/L on day 5 (approximately twofold higher than expected from the literature) despite good removal by hemodialysis with extraction ratios of 0.6 to 0.85 over the filter membrane. Negative effects of FBAL or enhancement of 5-FU-related toxicity could not be judged in this individual case, but further study is warranted to determine the possible benefits of more intensive dialysis treatment.

Simultaneous determination of F-beta-alanine and beta-alanine in plasma and urine with dual-column reversed-phase high-performance liquid chromatography

F-beta-Alanine and beta-alanine were detected in plasma and urine samples with fluorescence detection of orthophthaldialdehyde derivatives of F-beta-alanine and beta-alanine after separation with dual-column reversed-phase HPLC. The detection limits of F-beta-alanine and beta-alanine in the HPLC system were approximately 0.3 and 0.7 pmol, respectively. The procedure proved to be very reproducible with intra-assay RSDs and inter-assay RSDs being less than 8%. The usefulness of the method was demonstrated by the analysis of the F-beta-alanine and beta-alanine concentrations in plasma and urine samples from tumor patients treated with S-1 (Tegafur, 5-chloro-2,4-dihydroxypyridine and potassium oxonate in a molar ratio of 1:0.4:1).

Peripheral neuropathy associated with weekly oral 5-fluorouracil, leucovorin and eniluracil

5-Fluorouracil (5-FU)-associated neurotoxicity is uncommon; symptoms may occur abruptly or more gradually during the course of chemotherapy. Peripheral neuropathy with 5-FU therapy has only rarely been reported. Two patients treated in a phase I trial of oral 5-FU, leucovorin and eniluracil, an inhibitor of dihydropyrimidine dehydrogenase (DPD), developed delayed onset symptoms of unsteady gait and reduced sensation in the legs. Magnetic resonance imaging scans of the brain and neurologic examination did not support a CNS basis for the condition. Electromyograms and nerve conduction studies revealed sensorimotor polyneuropathy. Other common etiologies of peripheral neuropathy were excluded. The neurological condition of these patients stabilized after 5-FU dose reduction and partial resolution gradually occurred when protocol therapy was stopped. Although CNS symptoms may rarely complicate 5-FU therapy, peripheral neuropathy is unexpected. Patients with DPD deficiency treated with conventional doses of 5-FU typically develop acute CNS toxicity shortly after therapy, accompanied by extremely high systemic exposure to 5-FU. Patients with normal 5-FU clearance may also experience CNS toxicity, particularly with high-dose schedules, and both parent drug and its catabolites may be contributory. Since DPD was profoundly inhibited during eniluracil therapy in these two patients, it is likely that 5-FU or its active metabolites were contributing factors to the peripheral neuropathy.

Phase I and pharmacokinetic trial of weekly oral fluorouracil given with eniluracil and low-dose leucovorin to patients with solid tumors

PURPOSE

Fluorouracil (5-FU) given as a weekly, high-dose 24-hour infusion is active and tolerable. We evaluated an oral regimen of eniluracil (which inactivates dihydropyrimidine dehydrogenase [DPD]), 5-FU, and leucovorin to simulate this schedule.

PATIENTS AND METHODS

Patients received a single 24-hour infusion of 5-FU (2,300 mg/m(2) on day 2) with leucovorin (15 mg orally [PO] bid on days 1 through 3) to provide reference pharmacokinetic data. Two weeks later, patients began treatment with eniluracil (20 mg) and leucovorin (15 mg) (PO bid on days 1 through 3) and 5-FU (10 to 15 mg/m(2) PO bid on day 2).

RESULTS

Dose-limiting toxicity (diarrhea, neutropenia, and fatigue) was seen with 5-FU 15 mg/m(2) PO bid on day 2 given weekly for either 6 of 8 weeks or 3 of 4 weeks, whereas five of seven patients tolerated 5-FU 10 mg/m(2) PO bid given weekly for 3 of 4 weeks. Eniluracil led to a 35-fold reduction in 5-FU clearance. Fluoro-beta-alanine, a 5-FU catabolite, was not detected in plasma during oral 5-FU-eniluracil therapy. DPD activity was markedly suppressed in all patients during eniluracil therapy; the inactivation persisted after the last eniluracil dose; percentages of baseline values were 1.8% on day 5, 4.5% on day 12, and 23.6% on day 19.

CONCLUSION

The recommended oral dosage of 5-FU (10 mg/m(2) PO bid) given with eniluracil and leucovorin is approximately 115-fold lower than the reference dosage for 24-hour infusional 5-FU. This difference is greater than expected given the reduction in 5-FU clearance. DPD inactivation persisted for several weeks after completion of eniluracil therapy.

Gallbladder localization of (19)F MRS catabolite signals in patients receiving bolus and protracted venous infusional 5-fluorouracil

The hepatobiliary distribution of 5-fluorouracil (5FU) catabolites was investigated in nine patients. Using fluorine 3D-chemical shift imaging, four patients receiving protracted venous infusion of 5FU demonstrated catabolite localized to the gallbladder. No hepatobiliary fluorine signals were detected in three patients whose gallbladders were absent or abnormal. Signals from the gallbladder showed a 2.2-2.4 ppm high-frequency shift from alpha-fluoro-beta-alanine, suggesting the presence of alpha-fluoro-beta-alanine-bile-acid conjugates. 3D-chemical shift imaging of two patients receiving bolus 5FU revealed alpha-fluoro-beta-alanine to be localized to the liver within 1 hr of administration. In one patient examined 4 hr after bolus administration, catabolite signal was detected only in the gallbladder.