Is ABO-Incompatible Living Donor Liver Transplantation Really a Good Alternative for Pediatric Recipients?

BACKGROUND: ABO-incompatible (ABOi) living donor liver transplantation (LDLT) has been proposed to compensate for donor shortage. To date, few studies have reported detailed ABOi LDLT results in large series of pediatric patients. C4d complement deposition in graft capillaries has been reported to be associated with antibody-mediated rejection in solid organ transplantation. METHODS: A retrospective case-control study was conducted, comparing clinical outcomes of each of 34 consecutive pediatric ABOi LDLT recipients with those of 2 non-ABOi pairs (n = 68), matched according to pre-transplant diagnostic criteria, age, and date of transplantation. In addition, we studied the C4d immunostaining pattern in 22 ABOi and in 36 non-ABOi recipients whose liver biopsy was performed within the first 4 post-transplant weeks for suspected acute rejection. RESULTS: The incidence of biliary complications was higher in ABOi recipients (p < 0.05), as were the incidence of acute humoral rejection (p < 0.01) and the incidence of retransplantation (p < 0.05). All children who required retransplantation were older than 1 year at the time of ABOi LDLT. Positive C4d immunostaining was observed in 13/22 (59%) ABOi recipients versus 3/36 (8.3%) non-ABOi recipients (p < 0.0001). CONCLUSIONS: ABOi LDLT is a feasible option for pediatric end-stage liver disease but carries increased risks for the recipient, especially for children older than 1 year, even with a specific preparation protocol. C4d immunostaining may be a hallmark of acute humoral rejection in ABOi liver transplantation.

Antenatal Treatment with Intravenous Immunoglobulin to Prevent Gestational Alloimmune Liver Disease: Comparative Effectiveness of 14-Week versus 18-Week Initiation.

BACKGROUND: Antenatal therapy with high-dose intravenous immunoglobulin (IVIG) may prevent gestational alloimmune liver disease (GALD). OBJECTIVE: The objective of this study was to determine the effectiveness of this approach in a large cohort of women at risk for poor pregnancy outcome due to GALD. METHODS: Women with a history of affected offspring were provided antenatal IVIG treatment and data were acquired prospectively from 1997 to 2015. The outcomes of treated pregnancies were compared to those of untreated pregnancies, and the effectiveness of starting at 14 weeks was compared to that of starting at 18 weeks. RESULTS: A total of 188 treated pregnancies in 151 women were analyzed. Only 30% (n = 105) of untreated gestations resulted in healthy offspring as compared to 94% (n = 177) of treated pregnancies (p < 0.0001). Treated gestations of both the 14-week (n = 108) and the 18-week (n = 80) start cohort showed a decreased rate of fetal loss relative to untreated gestations (p < 0.0001). Equivalent outcomes were recorded in the 18-week versus the 14-week start cohort (p > 0.05). Few adverse events or complications of antenatal therapy were recorded. CONCLUSION: Antenatal therapy with high-dose IVIG initiated at either 18 or 14 gestational weeks effectively prevents poor outcome of pregnancies at risk for GALD.

Reduced feed intake of lactating primiparous sows is associated with increased insulin resistance during the peripartum period and is not modified through supplementation with dietary tryptophan.

The aim of this experiment was to investigate whether insulin resistance is related to the dietary concentration of Trp and the ADFI of primiparous sows having similar body conditions. Twenty-four primiparous sows were catheterized on d 97 of pregnancy. Blood samples were collected during 3 tests: after the ingestion of 1.5 kg of feed (meal test), after the intravenous infusion of 0.5 g of glucose/kg of BW (glucose tolerance test), and during an euglycemic hyperinsulinemic clamp with an infusion rate of 100 ng of insulin x kg of BW(-1) x min(-1). Both tests were performed at 4 stages at approximately d 103 and 110 of pregnancy and at d 3 and 10 of lactation. Sows were fed a diet containing 0.16 or 0.26% of total Trp (suboptimal vs. slight excessive Trp supply according to recommendations for lactating sows) from d 104 of pregnancy after the first clamp until weaning. The dietary treatment did not result in differences in ADFI, BW, and backfat changes, and growth of piglets during lactation. Plasma Trp concentration was greater for the sows allocated to the slight excessive Trp diet than for the sows allocated to the suboptimal Trp diet (P < 0.05). Plasma glucose, NEFA, and urea profiles during the meal tests were not affected by the dietary treatment. At d 3 of lactation, the insulin concentration at 105 (P = 0.03) and 120 min (P = 0.04) after meal intake was less for the sows allocated to the slight excessive Trp diet than for the sows allocated to the suboptimal Trp diet. On d 10 of lactation, the glucose half life (P = 0.03) and the time needed to reach 25% of the area under the insulin curve (P = 0.04) during the tolerance test were less for the sows allocated to the slight excessive Trp diet than for the sows allocated to the suboptimal Trp diet. The glucose infusion rate during euglycemic hyperinsulinemic clamps was similar in the 2 Trp groups of sows. Irrespective of the dietary treatment, the ADFI of the sows was negatively related to the glucose half life during the glucose tolerance test and positively related to the glucose infusion rate during the clamp (P < 0.05). This relationship observed with the tests performed during early lactation was already found with the tests performed during late pregnancy (P < 0.02). Present findings indicate that a dietary Trp supply of 0.26% does not increase feed intake in lactating primiparous sows. This result indicates that the interest in a Trp supplementation during the peripartum period can be questioned. Irrespective of the dietary treatment, the reasons why sows with similar rearing conditions develop different rates of insulin resistance during pregnancy remain to be elucidated.

Dietary fiber for pregnant sows: influence on sow physiology and performance during lactation.

This study was conducted to investigate the effects of feeding sows a bulky diet during gestation on their physiological and metabolic adaptations during the peripartum period, and to determine how these effects may relate to sow and piglet performances. From d 26 of gestation until farrowing, gilts were fed diets that contained 2.8 or 11.0% crude fiber (control and high-fiber diets, respectively, n = 9/group). Daily feed allowance provided the same amount of DE daily (33 MJ of DE/d). Throughout lactation, sows were allowed to consume a standard lactating sow diet ad libitum. Litters were standardized to 12 piglets beyond 48 h after birth. On d 105 of gestation, a jugular catheter was surgically implanted. Preprandial blood samples were collected from d 109 of gestation to the day after farrowing and on d 4, 18, and 26 of lactation. Meal tests and glucose tolerance tests were performed on d 109 of gestation and d 4 and 18 of lactation. During gestation, BW and backfat gain did not differ between treatment groups. During lactation, sows fed the high-fiber diet ate an average of 0.94 kg/d more than control sows (P < 0.02). Piglets born from sows fed the high-fiber diet grew faster than piglets from control sows (P = 0.03). Body weight and backfat losses did not differ between the 2 treatment groups. Sows fed the high-fiber diet during gestation had lesser concentrations of leptin before farrowing than control sows (P < 0.01). Leptin concentrations were negatively correlated with feed intake during lactation (P < 0.05). The prepartal increase in prolactin concentrations tended to be greater in sows fed the high-fiber diet than in control sows (P < 0.1). Preprandial concentrations of glucose, NEFA, lactate, and IGF-I fluctuated over time without significant treatment effect. Glucose half-life was shorter in late gestation than during both stages of lactation, but did not differ between sows in the 2 groups. In late gestation, the postprandial increases in glucose and insulin were delayed, and smaller, after a high-fiber meal than after a control meal. During lactation, glucose and insulin profiles after a standard meal did not differ between sows from treatment groups. In conclusion, the greater appetite of lactating sows fed a high-fiber diet during gestation does not seem related to changes in glucose and insulin metabolism and may be partly due to decreased secretion of leptin. The greater feed consumption was accompanied by a faster growth rate of piglets without sparing effect on maternal body reserves.

Liver cell transplantation for Crigler-Najjar syndrome type I: update and perspectives.

Liver cell transplantation is an attractive technique to treat liver-based inborn errors of metabolism. The feasibility and efficacy of the procedure has been demonstrated, leading to medium term partial metabolic control of various diseases. Crigler-Najjar is the paradigm of such diseases in that the host liver is lacking one function with an otherwise normal parenchyma. The patient is at permanent risk for irreversible brain damage. The goal of liver cell transplantation is to reduce serum bilirubin levels within safe limits and to alleviate phototherapy requirements to improve quality of life. Preliminary data on Gunn rats, the rodent model of the disease, were encouraging and have led to successful clinical trials. Herein we report on two additional patients and describe the current limits of the technique in terms of durability of the response as compared to alternative therapeutic procedures. We discuss the future developments of the technique and new emerging perspectives.

Thymidylate synthase and methylenetetrahydrofolate reductase gene polymorphisms: relationships with 5-fluorouracil sensitivity.

The relationship of thymidylate synthase (TS) and methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms on 5-fluorouracil (FU) sensitivity was tested on 19 human cancer cell lines (head and neck, breast, digestive tract) in the absence and presence of folinic acid (FA) supplementation. Thymidylate synthase polymorphisms in the 5' promoter region (double or triple tandem repeats) and 3' untranslated region (6-bp deletion) were analysed by PCR. The C677T and A1298C MTHFR polymorphisms were determined by melting curve analyses (LightCycler). Thymidylate synthase activity and intracellular concentration of the reduced folate 5-10 methylenetetrahydrofolate (CH(2)FH(4)) were measured (biochemical assays). Thymidylate synthase activity was significantly different according to 5' TS genotype, heterozygous cell lines (2R/3R) exhibiting higher TS activities than homozygous ones (P=0.05). However, whether in the absence or presence of FA, FU sensitivity was not statistically associated with either 5' or 3' TS polymorphism. Basal CH(2)FH(4) cellular concentrations were lowest in C677T homozygous wild-type (wt) (C/C) cell lines. FU sensitivity was not linked to C677T polymorphism. In contrast, there was a marked trend for a greater FU efficacy in mutated A1298C variants (C/C+A/C) as compared to wt homozygous cell lines (A/A) (P=0.055 and 0.085 without and with FA supplementation, respectively). These results suggest for the first time a potential role of A1298C MTHFR polymorphism on fluoropyrimidine sensitivity.

Effect of protein and lysine supply on performance, nitrogen balance, and body composition changes of sows during lactation.

Using 73 Large White gilts, we studied the lysine requirement during lactation. Sow and pig performance and nitrogen balance of sows were measured during the total 21-d lactation period. Variation in body composition of sows between farrowing and weaning was determined by the comparative slaughter technique. Two levels of crude protein (15.5 and 17.1%) were combined with two levels of L-lysine HCl supplementation (0 and .16%), resulting in four diets termed P1L1, P1L2, P2L2, and P2L3, containing .66, .77, .77, and .87% crude lysine, and 15.5, 15.5, 17.1, and 17.1% crude protein, respectively. Sows' feed intake, litter growth rate, and milk energy and protein output were not affected by the diet. Nitrogen balance over the total lactation increased (P < .001) with an increase in lysine and(or) protein (-11.7, -7.0, -3.4, and .4 g N/d for P1L1, P1L2, P2L2, and P2L3 diets, respectively). The losses of body weight and muscle weight were higher in P1L1 gilts (P < .01 and .05, respectively) than in gilts on other treatments, whereas the loss of adipose tissue and backfat was similar for the four groups. Multiple linear relationships between lysine intake and milk nitrogen output as predictors and nitrogen balance (N balance = -15.8 + 1.22 lysine - .63 N milk, R2 = .89) or variation of muscle weight (Vm = -477 + 30.1 lysine - 14.7 N milk, R2 = .70) as predicted values were calculated to estimate lysine requirement according to production performance of sows. Calculations show that for achieving a zero protein balance, 45 to 55 g/d of crude lysine are required for normal to high-yielding sows, respectively.

Energy metabolism in pregnant sows and newborn pigs.

Measurements of heat production(HP; indirect calorimetry) and its partition between maintenance, physical activity, thermoregulation, and thermic effect of feed or energy gain were carried out in sows maintained in different situations: primiparous or multiparous; pregnant or nonpregnant; thermoneutral or cold conditions; varied feeding levels; and varied body weights (BW). Metabolizable energy requirements for maintenance average 420 kJ/kg BW.75 at thermoneutrality and moderate physical activity. This value is not significantly affected by parity, pregnancy, and stage of pregnancy. Physical activity is a major factor causing differences in energy balance between sows because activity is variable and its energy cost (27 kJ.kg BW-.75.100 min-1 standing) is four to five times higher than in other species. Lower critical temperature (LCT) is approximately 20 degrees C in pregnant and individually housed sows, and daily HP is increased by approximately 15 kJ/kg BW.75 for each degree Celsius decrease of ambient temperature below LCT. Efficiencies of utilization of ME for meeting energy requirements for maintenance, maternal gain, and uterine gain are 77, 75, and 50%, respectively. Equations for predicting energy deposition in the uterus and mammary gland are proposed. In addition to activity and thermoregulation, energy requirements of pregnant sows depend on body reserves of energy. Studies with newborn pigs indicate that they are quite sensitive to ambient temperature (i.e., +25 J.kg BW-.75.min-1 for each degree Celsius decrease of temperature), and their LCT is 32 to 34 degrees C. The energy demand of pigs for thermoregulation just after birth relies mainly on carbohydrates from glycogen reserves or colostrum. Survival of newborn pigs is highly dependent on the supply of colostrum.

Relevance of tumoral folylpolyglutamate synthetase and reduced folates for optimal 5-fluorouracil efficacy: experimental data.

The purpose of this study was to investigate folate-related predictors of 5-fluorouracil (5-FU) cytotoxicity in the presence or absence of l-folinic acid (l-FA). Intracellular concentrations of the reduced folates (tetrahydrofolate + 5,10-methylenetetrahydrofolate) and folylpolyglutamate synthetase (FPGS) activity were determined in 14 human cancer cell lines expressing a spontaneous sensitivity to 5-FU. On these 14 cell lines grown without l-FA supplementation, a significant positive correlation was demonstrated between basal intracellular folate concentration and FPGS activity. 5-FU sensitivity (IC50 range 0.6-25.4 microM) was not related to the basal intracellular folate concentration, whereas, significantly, it was linked to FPGS activity (range 2.5-11.1 pmol/min/mg protein): the higher the FPGS activity, the greater the 5-FU sensitivity. Under l-FA supplementation (0.01-300 microM), intracellular reduced folates increased continuously without evidence of saturation in all cell lines; the pattern of accumulation was independent of the FPGS activity. l-FA enhanced 5-FU cytotoxicity by a factor of 1.9-6.4 in 12 of the 14 cell lines. In the 12 FA-sensitive cell lines, the l-FA concentrations allowing 90% of maximum 5-FU potentiation [l-FA]90 ranged between 0.7 and 107.9 micro M (median 1.9); in contrast, the intracellular concentrations of reduced folates allowing 90% of maximum 5-FU potentiation were much less variable (range 7.6-38.3, median 24.8 pmol/mg protein). In the presence of [l-FA]90, 5-FU sensitivity remained significantly correlated to the basal FPGS activity. In addition, reduced folates were measured in 96 tumoral samples (50 head and neck, 16 colon, 30 liver metastases from colorectal cancer) taken before treatment. Almost all investigated tumours had folate concentrations below the median concentration required for optimal 5-FU potentiation in vitro: median levels (range, pmol/mg protein) were 3.8 (0-17.7) for head and neck, 5.8 (2.3-12.0) for colon and 12.1 (1.7-118.5) for liver metastases. Above all, these data establish the relevance of FPGS activity for predicting the efficacy of 5-FU modulated by FA or not and point to the potential clinical interest of FPGS determination in human tumours.

Decreased folylpolyglutamate synthetase activity in tumors resistant to fluorouracil-folinic acid treatment: clinical data.

Thymidylate synthase (TS) is the main target for fluorouracil (FU). Optimal cellular concentrations of reduced folates in polyglutamated forms [via folylpolyglutamate synthetase (FPGS)] are necessary for achieving maximal TS inhibition. The aim of this multicentric prospective study was to analyze the link between clinical response to FU therapy for liver metastases of colorectal carcinoma and tumoral TS and FPGS activities. Forty-four advanced colorectal cancer patients (15 women and 29 men; median age 63, range, 27-78 years) receiving a standard FU-folinic acid protocol were included. A single hepatic tumoral biopsy was obtained systematically at the time of diagnosis. For 24 patients, a biopsy in the primary colon tumor was available. TS and FPGS activities were measured by radioenzymatic assays. Clinical response on hepatic metastases was 1 complete response, 12 partial responses, 14 stabilizations, and 17 progressions. In hepatic biopsies, TS activity (median, 185; range, <10-3111 fmol/min/mg protein) and FPGS activity (median, 1270; range, <400-3730 fmol/min/mg protein) exhibited a wide variability. TS activity in primary tumors (median, 461; range, 35-2565 fmol/min/mg protein) was significantly higher than in hepatic metastases. No difference was observed between primaries and metastases for FPGS. FPGS activity expressed in liver metastases was significantly correlated to that expressed in primaries. The distribution of TS activity in liver metastases was not significantly different between responsive and nonresponsive patients. However, FPGS activity measured in liver metastases was significantly higher in responsive patients (median, 1550 fmol/min/mg protein) than in nonresponsive patients (median, 1100 fmol/min/mg protein). A discriminant analysis revealed that 24 of the 25 patients exhibiting a liver FPGS activity 320 fmol/min/mg protein were nonresponding patients. These data establish for the first time the potential importance of tumoral FPGS activity for assessing FU-folinic acid responsiveness in the clinical setting.

Critical factors for optimizing the 5-fluorouracil-folinic acid association in cancer chemotherapy.

BACKGROUND: The 5-fluorouracil (FU)-folinic acid (FA) association has demonstrated clinical efficacy in colorectal cancer, both in adjuvant and metastatic situations. However, there is no clear consensus about the optimal FU-FA schedule and dose. In addition, it would be of interest to identify FU-FA-responsive tumors. DESIGN: Our purpose was to review preclinical and clinical data dealing with prediction of FU-FA sensitivity and optimization of FU-FA schedules. RESULTS: Preclinical studies have highlighted the importance of thymidylate synthase (TS), the cellular target of the FU-FA mechanism of action, for predicting FU sensitivity. It appears that the more sensitive cell lines express the lowest TS activity. Interestingly, the cell lines sensitive to FA supplementation are those more sensitive to FU. The role of TS in FU-FA responsiveness has been clearly demonstrated in patients with colorectal and gastric cancers. Preliminary in vitro and clinical data have shown that the folylpolyglutamate synthetase (FPGS), the enzyme responsible for folate polyglutamylation, is another promising tool for identifying FU-FA-responsive tumors. So far, results of clinical trials do not form a clear consensus regarding the need to administer high FA doses for improving FU-FA treatment. Experimental studies on human cancer cell lines have demonstrated the wide variability among cell lines, ranging from 0.05 to 200 microns, of 1 FA concentrations required for maximal FU potentiation. In addition, pharmacokinetic studies have reported a significant variability of active folates in plasma after administration of standard-dose FA. Altogether, these observations favour high-dose FA administration to achieve high folate concentrations in plasma and thus to counteract the variability of the 1 FA concentrations required. With respect to the choice of FU-FA schedule, it appears from experimental data that increasing the duration of exposure to FA enhances FU-FA cytotoxicity, probably through an increased formation of reduced folate polyglutamate forms. Considering the S-phase specificity of FU cytotoxicity as well as its rapid elimination from plasma, a schedule of prolonged exposure to both FU and FA should be considered preferable. CONCLUSIONS: Results of the new FU-FA administration schedules such as the one consisting of a 2-hour FA administration followed by a combination of FU bolus and FU infusion, or the chronomodulated FU-FA infusion, open up promising approaches for improving the therapeutic index of FU-FA chemotherapy. Finally, future clinical studies should investigate tumoral parameters pharmacologically linked to FU-FA sensitivity such as pre-treatment TS and FPGS activities. Such tumoral investigations along with FU and FA pharmacokinetic investigations should provide a better understanding of inter-patient variability in response to FU-FA therapy and an optimal management of this chemotherapy regimen.

Wide range for optimal concentration of folinic acid in fluorouracil modulation--experimental data on human tumour cell lines.

The clinical use of the fluorouracil (FU)-folinic acid (FA) combination is hampered by the still open choice of the optimal schedule, with marked controversy as concerns the optimal FA dose. This in vitro study on FU-FA combinations in 17 human cancer cell lines, representative of tumour types responding to FU-FA treatment, reassesses the notion of the optimal FA concentration. Cells were exposed for 5 days to various FU-FA concentrations (0.07-77 microM, 14 concentrations, for FU; and 0.0025-100 microM for FA). The growth inhibition was assessed by the MTT test. The investigated cell lines exhibited FU IC50 ranging from 0.4 to 38.9 microM (median 3.7 microM). In six out of 17 cell lines investigated, the addition of FA did not result in a substantial enhancement of FU cytotoxicity (group 1). For the remaining 11 cell lines responding to FA supplementation (group 2), the maximal enhancement factor ranged from 3 to 8, meaning that in the presence of optimal FA concentration, the efficient FU concentration (IC50) was reduced by between 3 and 8 as compared to the efficient FU concentration without FA supplementation. For cell lines responding to FA supplementation, the optimal FA concentrations ranged from 10(-7) to 4 x 10(-4) M (4000-fold range) with a median value at 9.6 x 10(-7) M. Distribution of cell doubling time was not significantly different between group 1 and group 2. In contrast, the FU IC50 were significantly different (P = 0.02) between group 1 (median 7.4 microM) and group 2 (median 2.2 microM), thus indicating that cell lines with the greatest FU cytotoxicity enhancement by FA were those intrinsically sensitive to FU and vice versa.

[l-folinic acid versus racemic folinic acid in the treatment of leukemia in children with high dose of methotrexate]. / Acide folinique forme 1 pure versus acide folinique forme racémique dans le traitement de la leucémie de l'enfant par méthotrexate forte dose.

Until now, folinic acid (FA) has been available the racemic mixture d1 FA, whose biological activity is supported by natural 1 FA. The purpose of this trial was to compare, on a pharmacokinetic, biological, and clinical basis, the racemic mixture dl FA with the pure 1 FA in the rescue of high-dose methotrexate (MTX) therapy. Eighteen children with acute lymphocytic leukemia (ALL) were entered in this trial planned with a cross-over design. Four cycles of MTX (5 g/m2, 24h CVI) were administered to each patient, with a 2-week interval between cycles. The rescue was achieved orally every 6h, starting 12h after the end of the MTX infusion, at a dose of 12 mg/m2 for dl FA and 6 mg/m2 for pure 1 FA. dl FA and 1 FA rescues were alternated from one cycle to the next. d FA, 1 FA, and the active metabolite 5-methyltetrahydrofolate (5-MTHF) were measured in plasma using a stereospecific HPLC assay. After administration of dl FA, the accumulation of d FA in plasma was confirmed: mean residual concentrations were 420 and 652 nM after 2 and 6 intakes respectively. Total active folate concentrations (1 FA + 5-MTHF) were similar between the two types of rescue: 92 and 100 nM respectively for dl FA rescue and 1 FA rescue after two intakes, 186 and 184 nM respectively for dl FA rescue and 1 FA rescue after six intakes. Intra-individual statistical analysis of total active folates (1 FA + 5-MTHF) performed on 17 patients did not show any significant difference between dl FA rescue and 1 FA rescue. For both types of rescue, MTX terminal half-lives were identical (average value 13.9 h). Considering each type of toxicity (hematologic, hepatic, renal and digestive) there was no significant difference in the proportion of toxic cycles following l FA rescue or dl FA rescue. In conclusion, the administration of the pure l FA, as compared with the administration of the racemic mixture, results in comparable blood profiles of active folates and MTX, and leads to equivalent treatment tolerance.

l-folinic acid versus d,l-folinic acid in rescue of high-dose methotrexate therapy in children.

BACKGROUND: At this time, folinic acid (FA) is commercially available as the racemic mixture d,l-FA, whose biological activity is supported by natural l-FA. The administration of d,l-FA results in the accumulation of d-FA in plasma relative to the active l-FA form; in vitro studies have shown that d-FA can compete with the polyglutamation of methotrexate (MTX). PURPOSE: Our purpose was to compare, on a pharmacokinetic, biological, and clinical basis, the racemic mixture d,l-FA with the pure l-FA in rescue of high-dose MTX therapy (5 g/m2) in children with acute lymphocytic leukemia (ALL). METHODS: Eighteen children with ALL were entered in this trial, which was planned with a crossover design. Four cycles of MTX were administered to each patient, and rescue was achieved orally every 6 hours at a dose of 12 mg/m2 for d,l-FA and 6 mg/m2 for pure l-FA. The d,l-FA and l-FA rescues were alternated from one cycle to the next. d-FA, l-FA, and the active metabolite 5-methyltetrahydrofolate (5-MTHF) were measured in plasma using a stereospecific high-performance liquid chromatography assay. RESULTS: Considering total active folate levels (l-FA + 5-MTHF), mean residual concentrations were similar for rescue by d,l-FA and l-FA, after two and six intakes, respectively: 92 and 186 nM for d,l-FA rescue versus 100 and 184 nM for l-FA rescue. Intra-individual comparison of total active folates (l-FA + 5-MTHF) did not show any significant difference between d,l-FA rescue and l-FA rescue. After administration of d,l-FA, the accumulation of d-FA in plasma was confirmed. For both types of FA rescue, MTX terminal half-lives were identical (average value, 13.9 hours). Considering each type of toxic effect (hematologic, hepatic, renal, and digestive), there was no significant difference in the proportion of toxic cycles following l-FA rescue or d,l-FA rescue. CONCLUSION: The administration of the pure l-FA, compared with the administration of the racemic mixture, results in comparable blood profiles of active folates and MTX, leads to equivalent treatment tolerance, and avoids the plasma accumulation of d-FA.

Evidence for CSF accumulation of 5-methyltetrahydrofolate during repeated courses of methotrexate plus folinic acid rescue.

In the first part of this study the availability of folinic acid (FA) and its main active circulating metabolite, 5-methyltetrahydrofolate (5-MTHF), were studied in plasma and cerebrospinal fluid (CSF) from normal subjects after i.v. administration of 100 and 250 mg of FA. 5-MTHF rapidly appeared in plasma, the maximum value being reached at the first observation time point (1 h). FA was eliminated in plasma more slowly than 5-MTHF. Between the two doses, there was no evidence of modification in pharmacokinetic parameters (terminal half-life, clearance) for either FA or 5-MTHF in plasma and CSF; 5-MTHF was the only product detectable in CSF. Considering FA plus 5-MTHF together, the AUC (area under the curve) ratios between CSF and plasma were close to 1%. 5-MTHF was cleared very slowly from CSF (t 1/2 = 85 h). This finding suggested possible accumulation of 5-MTHF in CSF during repeated administration of FA combined with medium or high dose MTX. In the second part of the study, dealing with a group of eight children treated by such protocols, an increase in CSF 5-MTHF was detected from cycle to cycle in five (r = 0.91, P less than 0.01) with a maximum at 5 x 10(-8) M. This progressive accumulation of 5-MTHF in CSF may have a negative effect on the local action of MTX and should be taken into account for therapeutic strategies designed for the management of meningeal leukaemia.