Saturable metabolism of continuous high-dose ifosfamide with mesna and GM-CSF: a pharmacokinetic study in advanced sarcoma patients. Swiss Group for Clinical Cancer Research (SAKK).

BACKGROUND: The aim of this study was to assess the pharmacology, toxicity and activity of high-dose ifosfamide mesna +/- GM-CSF administered by a five-day continuous infusion at a total ifosfamide dose of 12-18 g/m2 in adult patients with advanced sarcomas. PATIENTS AND METHODS: Between January 1991 and October 1992 32 patients with advanced or metastatic sarcoma were entered the study. Twenty-seven patients were pretreated including twenty-three with prior ifosfamide at less than 8 g/m2 total dose/cycle. In 25 patients (27 cycles) extensive pharmacokinetic analyses were performed. RESULTS: The area under the plasma concentration-time curve (AUC) for ifosfamide increased linearly with dose while the AUC's of the metabolites measured in plasma by thin-layer chromatography did not increase with dose, particularly that of the active metabolite isophosphoramide mustard. Furthermore the AUC of the inactive carboxymetabolite did not increase with dose. Interpatient variability of pharmacokinetic parameters was high. Dose-limiting toxicity was myelosuppression at 18 g/m2 total dose with grade 4 neutropenia in five of six patients and grade 4 thrombocytopenia in four of six patients. Therefore the maximum tolerated dose was considered to be 18 g/m2 total dose. There was one CR and eleven PR in twenty-nine evaluable patients (overall response rate 41%). CONCLUSION: Both the activation and inactivation pathways of ifosfamide are non-linear and saturable at high-doses although the pharmacokinetics of the parent drug itself are dose linear. Ifosfamide doses greater than 14-16 g/m2 per cycle appear to result in a relative decrease of the active metabolite isophosphoramide mustard. These data suggest a dose-dependent saturation or even inhibition of ifosfamide metabolism by increasing high dose ifosfamide and suggest the need for further metabolic studies.

Anti-idiotypic monoclonal antibody AB3, reacting with the primary antigen (CEA), can localize in human colon-carcinoma xenografts as efficiently as AB1.

BALB/c mice were immunized with anti-idiotypic monoclonal (MAb) antibody (anti-Id or Ab2) directed against an AB1 MAb anti-carcinoembryonic (CEA) in order to obtain AB3 MAbs (anti-anti-Id). AB3 MAbs were shown to recognise the primary antigen (CEA) and one of them was tested extensively in vitro and in vivo. This AB3 MAb was shown to bind specifically to CEA on frozen sections of a human colon carcinoma by immunoperoxidase. Scatchard plot analyses showed that the affinity of this AB3 was of the same order of magnitude as the AB1. In vivo experiments, in nude mice bearing CEA-producing human colon-carcinoma xenografts showed that up to 30% of the intravenously injected dose of 125I-labelled AB3 were localized per gram of tumour tissue. Furthermore, calculation of the ratios of AB3 concentration in the tumour over those in normal organs such as lung, liver, kidney, spleen and bone gave relatively high values similar to results obtained with AB1. All together our results show that AB3 can localize as efficiently and specifically in the tumour as AB1, despite the fact that the mice from which it was derived were immunized with a mouse MAb (AB2) and had never been exposed to CEA.

The biochemistry of drug metabolism : an introduction : part 6, Inter-individual factors affecting drug metabolism.

This review is part of a series of review articles on the metabolism of drugs and other xenobiotics published in Chemistry & Biodiversity. After a thorough discussion of metabolic reactions and their enzymes, this article focuses on genetically determined differences in drug and xenobiotic metabolism. After a short introduction on the causes for genetic differences, the first focus is on species differences in drug and xenobiotic metabolism. A major chapter is then dedicated to clinically relevant genetic polymorphisms in human drug metabolism and resultant ethnic differences. The last two chapters deal with sex-dependent differences in drug metabolism and personalized pharmacotherapy related to inter-individual differences in drug metabolism.

Fermentative 2-carbon metabolism produces carcinogenic levels of acetaldehyde in Candida albicans.

Acetaldehyde is a carcinogenic product of alcohol fermentation and metabolism in microbes associated with cancers of the upper digestive tract. In yeast acetaldehyde is a by-product of the pyruvate bypass that converts pyruvate into acetyl-Coenzyme A (CoA) during fermentation. The aims of our study were: (i) to determine the levels of acetaldehyde produced by Candida albicans in the presence of glucose in low oxygen tension in vitro; (ii) to analyse the expression levels of genes involved in the pyruvate-bypass and acetaldehyde production; and (iii) to analyse whether any correlations exist between acetaldehyde levels, alcohol dehydrogenase enzyme activity or expression of the genes involved in the pyruvate-bypass. Candida albicans strains were isolated from patients with oral squamous cell carcinoma (n = 5), autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) patients with chronic oral candidosis (n = 5), and control patients (n = 5). The acetaldehyde and ethanol production by these isolates grown under low oxygen tension in the presence of glucose was determined, and the expression of alcohol dehydrogenase (ADH1 and ADH2), pyruvate decarboxylase (PDC11), aldehyde dehydrogenase (ALD6) and acetyl-CoA synthetase (ACS1 and ACS2) and Adh enzyme activity were analysed. The C. albicans isolates produced high levels of acetaldehyde from glucose under low oxygen tension. The acetaldehyde levels did not correlate with the expression of ADH1, ADH2 or PDC11 but correlated with the expression of down-stream genes ALD6 and ACS1. Significant differences in the gene expressions were measured between strains isolated from different patient groups. Under low oxygen tension ALD6 and ACS1, instead of ADH1 or ADH2, appear the most reliable indicators of candidal acetaldehyde production from glucose.

Chloroplastic phosphoadenosine phosphosulfate metabolism regulates basal levels of the prohormone jasmonic acid in Arabidopsis leaves.

Levels of the enzymes that produce wound response mediators have to be controlled tightly in unwounded tissues. The Arabidopsis (Arabidopsis thaliana) fatty acid oxygenation up-regulated8 (fou8) mutant catalyzes high rates of alpha -linolenic acid oxygenation and has higher than wild-type levels of the alpha -linolenic acid-derived wound response mediator jasmonic acid (JA) in undamaged leaves. fou8 produces a null allele in the gene SAL1 (also known as FIERY1 or FRY1). Overexpression of the wild-type gene product had the opposite effect of the null allele, suggesting a regulatory role of SAL1 acting in JA synthesis. The biochemical phenotypes in fou8 were complemented when the yeast (Saccharomyces cerevisiae) sulfur metabolism 3'(2'), 5'-bisphosphate nucleotidase MET22 was targeted to chloroplasts in fou8. The data are consistent with a role of SAL1 in the chloroplast-localized dephosphorylation of 3'-phospho-5'-adenosine phosphosulfate to 5'-adenosine phosphosulfate or in a closely related reaction (e.g. 3',5'-bisphosphate dephosphorylation). Furthermore, the fou8 phenotype was genetically suppressed in a triple mutant (fou8 apk1 apk2) affecting chloroplastic 3'-phospho-5'-adenosine phosphosulfate synthesis. These results show that a nucleotide component of the sulfur futile cycle regulates early steps of JA production and basal JA levels.

Maturation of marginal zone and follicular B cells requires B cell activating factor of the tumor necrosis factor family and is independent of B cell maturation antigen.

B cells undergo a complex series of maturation and selection steps in the bone marrow and spleen during differentiation into mature immune effector cells. The tumor necrosis factor (TNF) family member B cell activating factor of the TNF family (BAFF) (BLyS/TALL-1) plays an important role in B cell homeostasis. BAFF and its close homologue a proliferation-inducing ligand (APRIL) have both been shown to interact with at least two receptors, B cell maturation antigen (BCMA) and transmembrane activator and cyclophilin ligand interactor (TACI), however their relative contribution in transducing BAFF signals in vivo remains unclear. To functionally inactivate both BAFF and APRIL, mice transgenic for a soluble form of TACI were generated. They display a developmental block of B cell maturation in the periphery, leading to a severe depletion of marginal zone and follicular B2 B cells, but not of peritoneal B1 B cells. In contrast, mice transgenic for a soluble form of BCMA, which binds APRIL, have no detectable B cell phenotype. This demonstrates a crucial role for BAFF in B cell maturation and strongly suggests that it signals via a BCMA-independent pathway and in an APRIL-dispensable way.

Revision anterior cruciate ligament reconstruction with quadriceps tendon-patellar bone autograft.

PURPOSE: To evaluate the cause of recurrent pathologic instability after anterior cruciate ligament (ACL) surgery and the effectiveness of revision reconstruction using a quadriceps tendon autograft using a 2-incision technique. TYPE OF STUDY: Retrospective follow-up study. METHODS: Between 1999 and 2001, 31 patients underwent ACL revision reconstruction because of recurrent pathologic instability during sports or daily activities. Twenty-eight patients were reviewed after a mean follow-up of 4.2 years (range, 3.3 to 5.6 years). The mean age at revision surgery was 27 years (range, 18 to 41 years). The average time from primary procedure to revision surgery was 26 months (range, 9 to 45 months). A clinical, functional, and radiographic evaluation was performed. Also magnetic resonance imaging (MRI) or computed tomography (CT) scanning was performed. The International Knee Documentation Committee (IKDC), Lysholm, and Tegner scales were used. A KT-1000 arthrometer measurement (MEDmetric, San Diego, CA) by an experienced physician was made. RESULTS: Of the failures, 79% had radiographic evidence of malposition of their tunnels. In only 6 cases (21%) was the radiologic anatomy of tunnel placement judged to be correct on both the femoral and tibial side. The MRI or CT showed, in 6 cases, a too-centrally placed femoral tunnel. After revision surgery, the position of tunnels was corrected. A significant improvement of Lachman and pivot-shift phenomenon was observed. In particular, 17 patients had a negative Lachman test, and 11 patients had a grade I Lachman with a firm end point. Preoperatively, the pivot-shift test was positive in all cases, and at last follow-up in 7 patients (25%) a grade 1+ was found. Postoperatively, KT-1000 testing showed a mean manual maximum translation of 8.6 mm (SD, 2.34) for the affected knee; 97% of patients had a maximum manual side-to-side translation <5 mm. At the final postoperative evaluation, 26 patients (93%) graded their knees as normal or nearly normal according to the IKDC score. The mean Lysholm score was 93.6 (SD, 8.77) and the mean Tegner activity score was 6.1 (SD, 1.37). No patient required further revision. Five patients (18%) complained of hypersensitive scars from the reconstructive surgery that made kneeling difficult. CONCLUSIONS: There were satisfactory results after ACL revision surgery using quadriceps tendon and a 2-incision technique at a minimum 3 years' follow-up; 93% of patients returned to sports activities. LEVEL OF EVIDENCE: Level IV, case series, no control group.

Rapid death and regeneration of NKT cells in anti-CD3epsilon- or IL-12-treated mice: a major role for bone marrow in NKT cell homeostasis.

Natural killer T (NKT) cells express a T cell receptor (TCR) and markers common to NK cells, including NK1.1. In vivo, NKT cells are triggered by anti-CD3epsilon MAb to rapidly produce large amounts of IL-4 and by IL-12 to reject tumors. We show here that anti-CD3epsilon MAb treatment rapidly depletes the liver (and partially the spleen) of NKT cells and that homeostasis is achieved 1 to 2 days later via NKT cell proliferation that occurs mainly in bone marrow. Similar results were obtained in mice treated with IL-12. Collectively, our data demonstrate that peripheral NKT cells are highly sensitive to activation-induced cell death and that bone marrow plays a major role in restoring NKT cell homeostasis.

Evaluation of the potential use of trabecular bone score to complement bone mineral density in the diagnosis of osteoporosis: a preliminary spine BMD-matched, case-control study.

The trabecular bone score (TBS) is a new parameter that is determined from gray-level analysis of dual-energy X-ray absorptiometry (DXA) images. It relies on the mean thickness and volume fraction of trabecular bone microarchitecture. This was a preliminary case-control study to evaluate the potential diagnostic value of TBS as a complement to bone mineral density (BMD), by comparing postmenopausal women with and without fractures. The sample consisted of 45 women with osteoporotic fractures (5 hip fractures, 20 vertebral fractures, and 20 other types of fracture) and 155 women without a fracture. Stratification was performed, taking into account each type of fracture (except hip), and women with and without fractures were matched for age and spine BMD. BMD and TBS were measured at the total spine. TBS measured at the total spine revealed a significant difference between the fracture and age- and spine BMD-matched nonfracture group, when considering all types of fractures and vertebral fractures. In these cases, the diagnostic value of the combination of BMD and TBS likely will be higher compared with that of BMD alone. TBS, as evaluated from standard DXA scans directly, potentially complements BMD in the detection of osteoporotic fractures. Prospective studies are necessary to fully evaluate the potential role of TBS as a complementary risk factor for fracture.

Fluoxetine regulates the expression of neurotrophic/growth factors and glucose metabolism in astrocytes.

Rationale The pharmacological actions of most antidepressants are ascribed to the modulation of serotonergic and/or noradrenergic transmission in the brain. During therapeutic treatment for major depression, fluoxetine, one of the most commonly prescribed selective serotonin reuptake inhibitor (SSRI) antidepressants, accumulates in the brain, suggesting that fluoxetine may interact with additional targets. In this context, there is increasing evidence that astrocytes are involved in the pathophysiology of major depression.Objectives The aim of this study was to examine the effects of fluoxetine on the expression of neurotrophic/growth factors that have antidepressant properties and on glucose metabolism in cultured cortical astrocytes.Results Treatment of astrocytes with fluoxetine and paroxetine, another SSRI antidepressant, upregulated brain-derived neurotrophic factor (BDNF), vascular endothelial growth factor (VEGF), and VGF mRNA expression. In contrast, the tricyclic antidepressants desipramine and imipramine did not affect the expression of these neurotrophic/growth factors. Analysis of the effects of fluoxetine on glucose metabolism revealed that fluoxetine reduces glycogen levels and increases glucose utilization and lactate release by astrocytes. Similar data were obtained with paroxetine, whereas imipramine and desipramine did not regulate glucose metabolism in this glial cell population. Our results also indicate that the effects of fluoxetine and paroxetine on glucose utilization, lactate release, and expression of BDNF, VEGF, and VGF are not mediated by serotonin-dependent mechanisms.Conclusions These data suggest that, by increasing the expression of specific astrocyte-derived neurotrophic factors and lactate release from astrocytes, fluoxetine may contribute to normalize the trophic and metabolic support to neurons in major depression.

Re-thinking cell cycle regulators: the cross-talk with metabolism.

Analysis of genetically engineered mice deficient in cell cycle regulators, including E2F1, cdk4, and pRB, showed that the major phenotypes are metabolic perturbations. These key cell cycle regulators contribute to lipid synthesis, glucose production, insulin secretion, and glycolytic metabolism. It has been shown that deregulation of these pathways can lead to metabolic perturbations and related metabolic diseases, such as obesity and type II diabetes. The cyclin-cdk-Rb-E2F1 pathway regulates adipogenesis in addition to its well-described roles in cell cycle regulation and cancer. It was also shown that E2F1 directly participates in the regulation of pancreatic growth and function. Similarly, cyclin D3, cdk4, and cdk9 are also adipogenic factors with strong effects on whole organism metabolism. These examples support the emerging notion that cell cycle regulatory proteins also modulate metabolic processes. These cell cycle regulators are activated by insulin and glucose, even in non-proliferating cells. Most importantly, these cell cycle regulators trigger the adaptive metabolic switch that normal and cancer cells require in order to proliferate. These changes include increased lipid synthesis, decreased oxidative metabolism, and increased glycolytic metabolism. In summary, these factors are essential regulators of anabolic biosynthetic processes, blocking at the same time oxidative and catabolic pathways, which is reminiscent of cancer cell metabolism.