The usefulness of in vitro models to predict the bioavailability of iron and zinc: a consensus statement from the HarvestPlus expert consultation

A combination of dietary and host-related factors determines iron and zinc absorption, and several in vitro methods have been developed as preliminary screening tools for assessing bioavailability. An expert committee has reviewed evidence for their usefulness and reached a consensus. Dialyzability (with and without simulated digestion) gives some useful information but cannot predict the correct magnitude of response and may sometimes predict the wrong direction of response. Caco-2 cell systems (with and without simulated digestion) have been developed for iron availability, but the magnitude of different effects does not always agree with results obtained in human volunteers, and the data for zinc are too limited to draw conclusions about the validity of the method. Caco-2 methodologies vary significantly between laboratories and require experienced technicians and good quality cell culture facilities to obtain reproducible results. Algorithms can provide semi-quantitative information enabling diets to be classified as high, moderate, or low bioavailability. While in vitro methods can be used to generate ideas and develop hypotheses, they cannot be used alone for important decisions concerning food fortification policy, selection of varieties for plant breeding programs, or for new product development in the food industry. Ultimately human studies are required for such determinations.     

CD40-CD40L expression during orthodontic tooth movement in rats

The aim of this study was to investigate the expression of the costimulatory molecules CD40 and CD40L in periodontal and bone cells in orthodontically treated and untreated teeth using immunohistochemistry. The upper first molars were moved mesially by a fixed appliance. In the experimental group, CD40+ cells were detected at both the tension and the resorption sides in fibroblast-, macrophage-, and dendritic-like cells. The staining was more pronounced on the resorption side. The strongest expression was observed on day 3, decreased on day 7, and reached a low level on day 10 after application of orthodontic force. In contrast, in the treated animals CD40 ligand was expressed on day 3, the expression was enhanced on day 7, and was more pronounced on day 10. CD40L-expressing cells were found predominantly around hyalinized tissue in the resorption zone and the tension areas of the distal root. CD40L was expressed in the bone marrow cells in the pressure zone. In the tension side, some cells of the cellular cementum expressed CD40L. The expression of CD40 and CD40L was low in untreated teeth. These results suggest that CD40-CD40L interaction appears to be an active process during orthodontic tooth movement and that orthodontic force induces T-cell activation. Such activation may be involved in the induction of inflammatory mediators and subsequent bone remodeling. In addition, this may lead to the generation of anti-inflammatory mediators that support defense mechanisms against root resorption, which depend on the type of immune response that is induced regarding CD40-CD40L expression.     

Effect of fractionated ifosfamide on the pharmacokinetics of irinotecan in pediatric patients with osteosarcoma

The combination of irinotecan (daily for 5 days for 2 consecutive weeks) and ifosfamide (daily on days 1 through 3) was investigated in children with osteosarcoma. Irinotecan pharmacokinetic investigations were performed before ifosfamide (day 1), after 3 days of ifosfamide (day 3), and 9 days after the end of ifosfamide (day 12). On day 3, the concentrations of irinotecan's active metabolite, SN-38, were below the limit of quantitation in two patients and were decreased in a third patient. The SN-38 area under the concentration-time curve remained below the day 1 value in two patients on day 12. The reduced area under the curve to the active metabolite SN-38 during ifosfamide therapy predicts a compromised efficacy of irinotecan in this combination.     

Phase I study of the combination of topotecan and irinotecan in children with refractory solid tumors

Purpose: We have shown in xenograft studies that the antitumor activities of topotecan and irinotecan are highly schedule- and dose-dependent, with a high frequency of response at low, protracted dose schedules. Preclinical and clinical data suggest that topotecan and irinotecan have different antitumor activities and mechanisms of resistance, and non-overlapping toxicities, providing a rationale for their combination. Combining both agents may increase the amount of camptothecin delivered to the tumor, without additive toxicity. Methods: We conducted a phase I study in children with refractory solid tumors to determine the maximum tolerated dose (MTD) of irinotecan when administered with a targeted systemic exposure (TSE) of topotecan and to define the dose-limiting toxicity (DLT) of this combination. Irinotecan was administered IV over 60 min followed by topotecan over 30 min daily for 5 days for two consecutive weeks. We initially fixed the topotecan-TSE to 80±10 ng*h/ml and investigated the ability to escalate irinotecan (starting dose 16 mg/m²/d). Topotecan and irinotecan pharmacokinetics were determined. Results: Eleven patients (median age 10 years) were enrolled. Owing to DLT, irinotecan was de-escalated to 12 (level −1; n=3) and 9 (level −2; n=3) mg/m²/day, and topotecan-TSE was reduced to 60±10 ng*h/ml (level −3; n=2). DLTs were neutropenia (n=8), typhlitis (n=5), and skin rash (n=1). MTD could not be reached. Median (range) irinotecan and topotecan lactone systemic clearances were 50.3 (16.6–76.2) l/h/m² and 27.6 (14.7–55.9) l/h/m², respectively. The pharmacokinetics profile of each agent was similar to that seen in previous single agent studies. One patient with neuroblastoma and one with rhabdomyosarcoma had a partial and a complete response, respectively. Conclusion: Despite promising antitumor activity, the combination of topotecan and irinotecan given on a protracted schedule does not warrant further development in children due to unacceptable toxicity. Contract grant sponsor: National Institutes of Health; Contract grant numbers P30 CA 21765 and CA 23099; Contract grant sponsor: American Lebanese Syrian Associated Charities (ALSAC).     

Combination of gemcitabine and docetaxel in the treatment of children and young adults with refractory bone sarcoma

BACKGROUND: The combination of gemcitabine and docetaxel has demonstrated promise in sarcomas diagnosed in adults. In the current study, the toxicity and efficacy of this combination were evaluated in pediatric sarcomas. METHODS: A retrospective case review of 22 patients with recurrent or refractory bone or soft-tissue sarcomas who received gemcitabine (at a dose of 675 mg/m(2) intravenously on Days 1 and 8) and docetaxel (at a dose of 75-100 mg/m(2) intravenously on Day 8) was undertaken. RESULTS: The patients (ages 8-23 years) received a total of 109 courses of chemotherapy (median, 4 courses; range, 1-13 courses). Seventeen patients had osteosarcoma, 2 patients had Ewing sarcoma family of tumors (ESFT), 1 patient had a malignant fibrous histiocytoma (MFH), 1 patient had a chondrosarcoma, and 1 patient had an undifferentiated sarcoma. Of the 14 patients evaluable for response, the patient with an MFH achieved a complete response (CR), 3 patients with osteosarcoma achieved a partial response (PR), and 2 patients (1 with ESFT and 1 with osteosarcoma) had stable disease (SD). The overall objective response (CR + PR) rate was 29%. Median duration of response (CR + PR + SD) was 4.8 months (range, 1.6-13 months). The toxicity was manageable and consisted primarily of thrombocytopenia and neutropenia. CONCLUSIONS: In the current study, gemcitabine in combination with docetaxel was found to be well tolerated and demonstrated antitumor activity in children and adolescents with recurrent or refractory osteosarcoma and MFH. Further evaluation of this drug combination is warranted in these patients.     

Analysis of biologic surrogate markers from a Children's Oncology Group Phase I trial of gefitinib in pediatric patients with solid tumors

This trial evaluated the effect of gefitinib on the plasma circulating levels of epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF), matrix metalloproteinases (MMP)-2 and -9 of patients treated on a pediatric Phase I trial. Complete plasma correlative studies were obtained from 16 of the 25 enrolled patients. There was a trend for lower MMP-2 baseline levels in patients with partial response or stable disease. The Ewing sarcoma from the only patient with partial response lacked egfr mutations. Gefitinib did not induce any significant variation in the levels of the assessed parameters, and none of these determinations showed significant predictive or prognostic value.     

Anti-colon cancer effects of Salograviolide A isolated from Centaurea ainetensis

The antitumor activity of extracts of Centaurea ainetensis (C. ainetensis), a plant endemic to Lebanon, was investigated in human colon carcinoma cells. At concentrations that were non-cytotoxic to normal human intestinal epithelial cells, the crude extract inhibited the proliferation of a host of colon-derived cancer cells. The crude extract effect was then investigated in HCT-116 (p53+/+) cells, most sensitive to treatment and was found to cause apoptosis, increase the Bax/Bcl-2 ratio, p53 and p21 protein levels and reduce cyclin B1 proteins. In vivo, the crude extract injected intraperitoneally before the subcutaneous injection of the carcinogen 1,2-dimethylhydrazine, drastically reduced the number of tumors and decreased the mean size of aberrant crypt foci. Further bioassay-guided fractionation of the crude extract resulted in the identification of the bioactive molecule Salograviolide A, a Sesquiterpene Lactone, to which the growth inhibition in colon cancer was linked. Salograviolide A, at non-cytotoxic concentrations to normal human intestinal cells, reduced the growth of colon cancer cell lines. Salograviolide A induced growth inhibition and resulted in an increased preG1 phase and presumably apoptosis induction which was further confirmed by TUNEL. These data support the testing of the C. ainetensis extract and its bioactive molecule, Salograviolide A, in colon cancer treatment.