Differential protective effects of varying degrees of hypoxia on the cytotoxicities of etoposide and bleomycin

Summary Oxygen is thought to be involved both directly and indirectly in the mechanisms of action of several anticancer agents. We studied the effects of various oxygen concentrations on the cytotoxicities of the following drugs: bleomycin (BLM), etoposide (VP-16), doxorubicin (DOX), and mitomycin C (MMC). Human sarcoma cells, MESSA, were exposed to drug for 1 h at one of several oxygen concentrations: less than 1%, 2.5%, 5%, 21%, and 95%. Cytotoxicity was assessed by cellular incorporation of ³H-thymidine into DNA 5 days after drug exposure. Control experiments varying oxygen concentration without drugs demonstrated toxicity only at the highest concentration (95%). Three different responses of drug sensitivity to varying oxygen tensions were observed. BLM, which has been shown to utilize oxygen as a substrate in generating free radicals and producing DNA scission, demonstrated a progressive increase in cytotoxicity over the entire range of increasing oxygen concentrations. This is consistent with the model of a BLM-cation-oxygen complex and catalytic reduction of oxygen. VP-16, which also produces DNA strand breakage but by interaction with topoisomerase II, exhibited a threshold response. VP-16 toxicity was ameliorated by anoxic conditions (less than 1% O₂), but not by oxygen concentrations of 2.5%–95%. The reason for this protective effect of anoxia with VP-16 is not clear. In contrast, acute anoxia had no effect on the cytotoxicities of DOX and MMC. We conclude that acute hypoxia protects cells from both BLM and VP-16 but that the nature of that protection is different. VP-16 toxicitiy is blunted only by severe anoxia, wheaeas BLM exhibits a dose response effect over the entire range of oxygen concentrations.Supported by NIH grant CA-27478 from the US Department of Health and Human Services, and by the American Lung Association. Dr. Sikic is a recipient of a Faculty Development Award in Clinical Pharmacology from the Pharmaceutical Manufacturer's Association Foundation.     

Clinical approach to normal intraocular pressure glaucoma

Normal intraocular pressure (IOP) glaucoma is a clinical condition characterized by pathologic optic nerve excavation and visual field impairment, defined as optic neuropathy with certain features of a disease known as glaucoma. Glaucomatous optic nerve lesion is characterized by optic disk excavation or depression, however, this feature may greatly vary. The level of IOP is considered only one of the multiple risk factors involved in the disease development. In normal IOP glaucoma, papillary lesions and visual field impairments may differ from those occurring in primary open-angle glaucoma. In modern ophthalmology, the terminology has been modified, so the term low IOP glaucoma has been replaced by the term normal IOP glaucoma. It is now believed that various factors play a role in the development of glaucomatous optic neuropathy in normal IOP glaucoma and show variable interference depending on IOP level. Additional studies are needed to define these interactions and their impact on the mechanism of glaucomatous excavation. This will hopefully pave the way to new therapeutic approaches and help in clinical decisions concerning the prognosis and treatment of individual patients.     

Lid retraction etiology

The upper lid position is abnormal if it exposes a white band of sclera between the lid margin and the upper corneal limbus while the retracted lower lid lies below the inferior corneal margin and is tethered to the orbital margin. Lid retraction is a sign of many congenital and acquired diseases and is characterised by multifactorial etiology. The aim of this study was to discuss the etiology of lid retraction divided into four categories: neurogenic, myogenic, mechanical and miscellaneous, what suggests a successful differential diagnostic and therapeutic approach.     

Pharmacokinetics and protein binding of cis-dichlorodiammine platinum (II) administered as a one hour or as a twenty hour infusion

Summary The pharmacokinetics of cis-dichlorodiamminoplatinum (II) (cisplatin) have been studied in seven patients, of whom four received the drug as a one hour infusion and three received it as a 20 h infusion. The patients receiving the drug over one hour exhibited biphasic clearance of total platinum with a rapid initial phase (8.7–22.5 min) and a prolonged second phase (30.5–106 h). Free (ultrafilterable) cisplatin was readily detectable in this group and was rapidly cleared (half-life about 22 min). The volume of distribution of the drug was 50.3–65.6 liters and it was 26.6–50% excreted in the urine in 48h. In the patients receiving the 20 h infusion, a more complex plasma elimination curve was seen, with the appearance of a secondary peak. Free drug was not detectable in these patients and they showed less urinary excretion (21.4–25.9% at 48 h) than the one hour group. Cisplatin was bound to several plasma proteins, including albumin, transferrin, and -globulin. The data indicate that cisplatin is retained in the body more extensively after a 20 h infusion than after a one hour infusion.     

Phase I and pharmacokinetic study of BMS-188797, a new taxane analog, administered on a weekly schedule in patients with advanced malignancies.

PURPOSE: The purpose of this study was to establish the maximum tolerated dose (MTD), dose-limiting toxicities (DLTs), and preliminary activity of BMS-188797 administered weekly. EXPERIMENTAL DESIGN: Patients with advanced malignancies were treated with escalating doses of BMS-188797 on a weekly schedule as a 1-h i.v. infusion. Plasma sampling was performed to characterize the pharmacokinetics of BMS-188797. RESULTS: Eighteen patients with advanced malignancies were enrolled at three dose levels ranging from 35 to 65 mg/m(2). The number of patients evaluated at each dose level was as follows: 35 mg/m(2) (n = 3); 50 mg/m(2) (n = 9); and 65 mg/m(2) (n = 6). At 65 mg/m(2), three of six patients had a DLT (one had grade 4 neutropenia lasting >7 days, and two had grade 3 diarrhea). Expansion of the 50-mg/m(2) dose cohort to nine patients established this dose as the MTD, with one patient experiencing a DLT (grade 4 neutropenia with fever). Two partial responses were observed (lung cancer, 7+ months; ovarian cancer, 6+ months durations), as well as two minor responses (esophageal cancer, 5 months; ovarian cancer, 5 months). Both patients with partial responses had been clinically resistant to paclitaxel. Plasma pharmacokinetic mean values of maximum concentration (C(max)) and area under the curve (AUC(0-48)) increased in a dose-dependent manner within the range of doses used in this study, and in three of four patients, the DLTs correlated with AUC. CONCLUSIONS: The MTD and the recommended Phase II dose of weekly BMS-188797 is 50 mg/m(2). The drug demonstrates antitumor activity in taxane-refractory solid tumors and is now being evaluated in combination with carboplatin.     

Phase II study of gefitinib, fluorouracil, leucovorin, and oxaliplatin therapy in previously treated patients with metastatic colorectal cancer.

PURPOSE: To investigate the gefitinib, fluorouracil (FU), leucovorin, and oxaliplatin regimen (IFOX) in previously treated patients with metastatic colorectal cancer. PATIENTS AND METHODS: Eligible patients had stage IV colorectal adenocarcinoma and had demonstrated progression or intolerance to a prior chemotherapy regimen not including oxaliplatin. Each cycle consisted of 14 days. Cycle 1 consisted of oxaliplatin 85 mg/m2 intravenously (IV) during 2 hours on day 1, hours 0 to 2; leucovorin 200 mg/m2 IV on days 1 and 2, hours 0 to 2; FU 400 mg/m2 IV push on days 1 and 2; and FU 600 mg/m2 IV on days 1 and 2, hours 2 to 24 (FOLFOX-4). All subsequent cycles consisted of FOLFOX-4 with gefitinib at 500 mg/d administered orally throughout the 14-day cycle. RESULTS: Twenty-seven patients were enrolled onto the study. The median number of prior chemotherapy regimens was two, and 74% of all patients received prior irinotecan. Nine of the 27 patients (33%) and six of the 20 patients (30%) who had prior FU and irinotecan had a partial response by Response Evaluation Criteria in Solid Tumors Group criteria. Median overall survival was 12.0 months. Median event-free survival was 5.4 months. Grade 3 to 4 toxicities included neutropenia (48%), diarrhea (48%), nausea (22%), and vomiting (15%). CONCLUSION: IFOX is an active regimen in patients with previously treated metastatic colorectal adenocarcinoma, demonstrating higher response rates than those reported with FOLFOX-4 alone in a similar patient population.     

Enhancement of paclitaxel and carboplatin therapies by CCL2 blockade in ovarian cancers

Ovarian cancer is associated with a leukocyte infiltrate and high levels of chemokines such as CCL2. We tested the hypothesis that CCL2 inhibition can enhance chemotherapy with carboplatin and paclitaxel. Elevated CCL2 expression was found in three non‐MDR paclitaxel resistant ovarian cancer lines ES‐2/TP, MES‐OV/TP and OVCAR‐3/TP, compared to parental cells. Mice xenografted with these cells were treated with the anti‐human CCL2 antibody CNTO 888 and the anti‐mouse MCP‐1 antibody C1142, with and without paclitaxel or carboplatin. Our results show an additive effect of CCL2 blockade on the efficacy of paclitaxel and carboplatin. This therapeutic effect was largely due to inhibition of mouse stromal CCL2. We show that inhibition of CCL2 can enhance paclitaxel and carboplatin therapy of ovarian cancer.     

In vivo toxicity evaluation of two polyoxotungstates with potential antidiabetic activity using Wistar rats as a model system

In this study, the in vivo hypoglycemic effect of a donut-shaped polyanion salt (NH₄)₁₄[Na@P₅W₃₀O₁₁₀]·31H₂O {NaP₅W₃₀} and its Ag-containing derivative K₁₄[Ag@P₅W₃₀O₁₁₀]·22H₂O·6KCl {AgP₅W₃₀}, as well as their hepatotoxicity and nephrotoxicity, was evaluated. In the screening hypoglycemic study, Wistar albino rats with streptozotocin induced diabetes were treated intraperitoneally with three single doses (5, 10, and 20 mg per kg per b.w.) of both investigated polyoxotungstates. The blood glucose levels, measured before and after 2, 4 and 6 h polyoxotungstate application, showed that both studied compounds induced the most pronounced and time dependent glucose lowering effects at the doses of 20 mg kg⁻¹. Thus, daily doses of 20 mg kg⁻¹ were administered to Wistar albino rats orally for 14 days in further toxicity examinations. The serum glucose concentration and biochemical parameters of kidney and liver function, as well as a histopathological analysis of kidney and liver tissues were evaluated 14 days after the polyoxotungstate administration. Both investigated compounds did not induce statistically significant alterations of the serum glucose and uric acid concentrations, as well as some of the liver function markers (serum alanine and aspartate aminotransferases, and alkaline phosphatase activities). However, the significant decrease in serum total protein and albumin concentrations and the increase in biochemical parameters of renal function – serum urea (up to 63.1%) and creatinine concentrations (up to 23.3%) were observed for both polyoxotungstates. In addition, the detected biochemical changes were in accordance with kidney and liver histhopathological analysis. Accordingly, the hepatotoxic and nephrotoxic effects of these potential antidiabetic polyoxotungstates could be considered as mild.

Study of the in vivo hypoglycemic effect, hepatotoxicity and nephrotoxicity of a donut-shaped polyanion salt (NH₄)₁₄[Na@P₅W₃₀O₁₁₀]·31H₂O {NaP₅W₃₀} and its Ag-containing derivative K₁₄[Ag@P₅W₃₀O₁₁₀]·22H₂O·6KCl {AgP₅W₃₀}.     

Geometric cues for directing the differentiation of mesenchymal stem cells

Significant efforts have been directed to understanding the factors that influence the lineage commitment of stem cells. This paper demonstrates that cell shape, independent of soluble factors, has a strong influence on the differentiation of human mesenchymal stem cells (MSCs) from bone marrow. When exposed to competing soluble differentiation signals, cells cultured in rectangles with increasing aspect ratio and in shapes with pentagonal symmetry but with different subcellular curvature—and with each occupying the same area—display different adipogenesis and osteogenesis profiles. The results reveal that geometric features that increase actomyosin contractility promote osteogenesis and are consistent with in vivo characteristics of the microenvironment of the differentiated cells. Cytoskeletal-disrupting pharmacological agents modulate shape-based trends in lineage commitment verifying the critical role of focal adhesion and myosin-generated contractility during differentiation. Microarray analysis and pathway inhibition studies suggest that contractile cells promote osteogenesis by enhancing c-Jun N-terminal kinase (JNK) and extracellular related kinase (ERK1/2) activation in conjunction with elevated wingless-type (Wnt) signaling. Taken together, this work points to the role that geometric shape cues can play in orchestrating the mechanochemical signals and paracrine/autocrine factors that can direct MSCs to appropriate fates.