Pharmacokinetics and safety of ILX23-7553, a non-calcemic-vitamin D3 analogue, in a phase I study of patients with advanced malignancies

Purpose: Differentiation therapy is an alternative to chemotherapy with potentially less toxicity, improved quality of life, and survival. We conducted a phase I trial of ILX23-7553, a formulation of 1,25-dihydroxy-16-ene-23-yne-vitamin D₃, a 1,25-dihydroxyvitamin D₃ analog with preclinically demonstrated antitumor and differentiating effects and diminished hypercalcemic effects. Patients and methods: The protocol consisted of five daily oral treatments during 14-day cycles at 15 dose levels from 1.3 to 45.0g/m²/day. We treated 42 heavily pretreated patients who had a variety of malignancies with 162 treatment cycles, and obtained pharmacokinetics from three patients at the two highest dose levels. Results: There were no grade 3 or 4 toxicities. Grade 1–2 toxicities included diarrhea, nausea, fatigue, constipation, and one grade 1 hypercalcemia. Average day 6 calcium was 9.26 ± 0.55mg/dl in cycle 1 and 9.30 ± 0.67mg/dl in cycle 2. Pharmacokinetics at dose levels 14 (40g/m²/day) (1 patient) and 15 (45g/m²/day) (2 patients) demonstrated an average C _max of 30.4 ± 7.8pg/ml (0.07nM) and 104 ± 38.2pg/ml (0.25nM), and AUCs of 222.5 ± 225.2pg·h/ml and 855 ± 536pgh/ml, respectively. Eight patients (19%) had stable disease. While in vitro effects have been reported at these concentrations, they were at least 10-fold lower than ED₅₀s, and the study was terminated before an MTD was reached. Conclusion: The drug is safe and has potential benefits at serum concentrations where effects begin to be noted in vitro. Further study is needed with a reformulated higher unit dose compound to determine the safety and efficacy of higher serum concentrations.     

Effects of Aniline–An Aromatic Amine to Some Freshwater Organisms

We determined the acute and chronic toxicity of aniline to tilapia (Oreochromis mossambicus), cladoceran crusatcea (Moina micrura) and oligochaete worm (Branchiura sowerbyi) using static bioassay tests. The 96h LC₅₀ values of aniline for O. mossambicus, M. micrura and B. sowerbyi were 69.4, 0.6 and 586mg l^–1 respectively. Tilapia responded to even low concentrations of aniline: the fish lost appetite at aniline concentrations as low as 0.02mg l^–1. A 90 d outdoor bioassay with tilapia showed that 0.02mg l^–1 aniline reduced fish yield, specific growth rate and food conversion efficiency. Reproductive functions of fish were affected by aniline at a concentration of 0.5mg l^–1 and above. Dissolved oxygen, primary productivity and plankton population of the test medium also were significantly reduced at 2.65 and 6.94mg l^–1 aniline.     

Haem Peroxidase Activity in Daphnia magna: A Biomarker for Sub-lethal Toxicity Assessments of Kerosene-contaminated Groundwater

A novel biomarker was developed in Daphnia magna to detect organic pollution in groundwater. The haem peroxidase assay, which is an indirect means of measuring oxidase activity, was particularly sensitive to kerosene contamination. Exposure to sub-lethal concentrations of kerosene-contaminated groundwater resulted in a haem peroxidase activity increase by dose with a two-fold activity peak at 25%. Reproduction in D. magna remained unimpaired when exposed to concentrations below 25% for 21 days, and a decline in fecundity was only observed at concentrations above the peak in enzyme activity. The measurement of haem peroxidase activity in D. magna detected sublethal effects of kerosene in just 24h, whilst offering information on the health status of the organisms. The biomarker may be useful in determining concentrations above which detrimental effects would occur from long-term exposure for fuel hydrocarbons. Moreover, this novel assay detects exposure to chemicals in samples that would normally be classified as non-toxic by acute toxicity tests.     

Phase II trial and pharmacokinetic study of thalidomide in patients with metastatic colorectal cancer

Introduction. This study was designed to estimate the percentage of objective tumor responses, toxicity profile, and obtain additional information about the plasma pharmacokinetics of thalidomide in patients with refractory and progressing metastatic colorectal cancer. Study design. This phase II clinical trial was conducted according to the two-stage Simon method with the inclusion of consecutive patients. The study protocol was approved by the Institutional Review Board (IRB) of the Academic Hospital (HCPA) of the Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Brazil. Patients and methods. Seventeen patients with previously treated, refractory progressive metastatic colorectal cancer were eligible. Six patients had prior radiotherapy. The patients had a median of one previous chemotherapy regimen. Patients were initially treated with 200mg/day of thalidomide with an increase in dose by 200mg/day every 2 weeks until a final daily dose of 800mg/day was achieved. Patients were evaluated every 8 weeks for response by radiographic criteria. Plasma pharmacokinetics studies were performed in four patients at 200mg level and in one patient at 600mg during the first 24h. Main outcome measures and results. A total of 17 patients were accrued, all of them being evaluable for toxicity and 14 for response. Thalidomide was well tolerated, with constipation, somnolence, dizziness, and dry mouth being the major toxicities. There were no objective response or stable disease. The median survival was 3.6 months. Single-agent thalidomide is a generally well-tolerated drug that showed no antitumor activity in patients with advanced pretreated metastatic colorectal cancer. Although thalidomide did not show antitumor activity in this patient population, future studies of this agent in patients at initial stages of the disease (when its antiangiogenic properties may be more relevant to disease progression) could be considered.     

Estimating toxic damage to soil ecosystems from soil organic matter profiles

Concentrations of particulate and total organic matter were measured in upper soil profiles at 26 sites as a potential means to identify toxic damage to soil ecosystems. Because soil organic matter plays a role in cycling nutrients, aerating soil, retaining water, and maintaining tilth, a significant reduction in organic matter content in a soil profile is not just evidence of a change in ecosystem function, but of damage to that soil ecosystem. Reference sites were selected for comparison to contaminated sites, and additional sites were selected to illustrate how variables other than environmental contaminants might affect the soil organic matter profile. The survey was undertaken on the supposition that environmental contaminants and other stressors reduce the activity of earthworms and other macrofauna, inhibiting the incorporation of organic matter into the soil profile. The profiles of the unstressed soils showed a continuous decrease in organic matter content from the uppermost mineral soil layer (0–2.5cm) down to 15cm. Stressed soils showed an abrupt decrease in soil organic matter content below a depth of 2.5cm. The 2.5–5.0cm layer of stressed soils–such as found in a pine barren, an orchard, sites contaminated with zinc, and a site with compacted soil–had less than 4% total organic matter and less than 1% particulate organic matter. However, damaged soil ecosystems were best identified by comparison of their profiles to the profiles of closely matched reference soils, rather than by comparison to these absolute values. The presence or absence of earthworms offered a partial explanation of observed differences in soil organic matter profiles.     

Pharmacokinetic Drug–Drug Interaction of the Novel Anticancer Agent E7070 and Acenocoumarol

E7070 is a novel sulfonamide anticancer agent that arrests cancer cells at the G1/S boundary of the cell cycle. Three patients receiving chronic therapy with the oral anticoagulant acenocoumarol experienced bleeding and/or a prolonged prothrombin time after treatment with E7070 at a dose of 700mg/m² given as a 1-h infusion. In vitro studies have shown that E7070 has the potential to inhibit several cytochrome P450 (CYP)-enzymes, including CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A4. The major enzyme involved in the metabolism of acenocoumarol in man is CYP2C9. This study was performed to investigate the interaction between E7070 and acenocoumarol.Blood samples were obtained from two patients receiving daily oral maintenance treatment with acenocoumarol both prior to and following treatment with E7070. In addition, we incubated acenocoumarol enantiomers with pooled human microsomes with and without E7070 and measured the in vitro plasma protein binding of acenocoumarol after incubation with E7070. Pharmacokinetic parameters of acenocoumarol were calculated by noncompartmental analysis and revealed that in both patients the area under the concentration–time curve up to 24h after the acenocoumarol administration was higher following E7070 (2.56 and 1.58h*mol/L) compared to the systemic exposure in the absence of E7070 (1.87 and 1.23h*mol/l). The formation of acenocoumarol metabolites was retarded by E7070 at already low concentrations (2.1M). The plasma protein binding of acenocoumarol was reduced at higher concentrations of E7070 (259M).These results indicate that E7070 may primarily interact with acenocoumarol by reducing its systemic clearance. Displacement of acenocoumarol's plasma protein binding by E7070 may also occur but to a minor extent. In the absence of careful monitoring this drug–drug interaction may result in hypoprothrombinemia and a hemorrhagic tendency.     

Toxicity of Lithium to Three Freshwater Organisms and the Antagonistic Effect of Sodium

Lithium (Li) is the lightest metal and occurs primarily in stable minerals and salts. Concentrations of Li in surface water are typically <0.04mg l^–1 but can be elevated in contaminated streams. Because of the general lack of information concerning the toxicity of Li to common toxicity test organisms, we evaluated the toxicity of Li to Pimephales promelas (fathead minnow), Ceriodaphnia dubia, and a freshwater snail (Elimia clavaeformis). In the laboratory, the concentration of Li that inhibited P. promelas growth or C. dubia reproduction by 25% (IC25) was dependant upon the dilution water. In laboratory control water containing little sodium (2.8mg l^–1), the IC25s were 0.38 and 0.32mg Li l^–1 and in ambient stream water containing 17mg Na l^–1, the IC25s were 1.99 and 3.33, respectively. A Li concentration of 0.15mgl^–1 inhibited the feeding of E. clavaeformis in laboratory tests. Toxicity tests conducted to evaluate the effect of sodium on the toxicity of Li were conducted with fathead minnows and C. dubia. The presence of sodium greatly affected the toxicity of Li. Fathead minnows and Ceriodaphnia, for example, tolerated concentrations of Li as great as 6mg l^–1 when sufficient Na was present. The interaction of Li and Na on the reproduction of Ceriodaphnia was investigated in depth and can be described using an exponential model. The model predicts that C. dubia reproduction would not be affected when animals are exposed to combinations of lithium and sodium with a log ratio of mmol Na to mmol Li equal to at least 1.63. The results of this study indicate that for most natural waters, the presence of sodium is sufficient to prevent Li toxicity. However, in areas of historical disposal or heavy processing or use, an evaluation of Li from a water quality perspective would be warranted.     

Preliminary assessment of perchlorate in ecological receptors at the Longhorn Army Ammunition Plant (LHAAP), Karnack, Texas

There have been increasing human health and ecological concerns about ionic perchlorate (ClO₄) since it was detected in drinking water sources in 1997. Perchlorate is known to affect thyroid function, causing subsequent hormone disruption and potential perturbations of metabolic activities. According to current estimates, perchlorate is found in the surface or groundwater of 14 states, including Texas. Longhorn Army Ammunition Plant, located in east central Texas, was a facility historically associated with perchlorate-containing propellants and rocket motors. Subsequently, perchlorate contamination in ground and surface waters at the facility has been reported. Soil, sediment, water, vegetation, and animal tissue samples were collected from several locations within the plant for a preliminary site assessment of perchlorate contamination. Perchlorate concentrations ranged from 555–5,557,000ppb in vegetation, 811–2038ppb in aquatic insects, below detection limits (ND) to 207ppb in fish, ND-580ppb in frogs, and ND–2328ppb in mammals.Consistent with our hypothesis, aquatic organisms inhabiting perchlorate-contaminated surface water bodies contained detectable concentrations of perchlorate. Additionally, terrestrial organisms were exposed through pathways not necessarily related to contaminated surface waters. Therefore, these data demonstrate that aquatic and terrestrial species are exposed to perchlorate in the environment. To our knowledge, this represents the first incidence of perchlorate exposure among wild animals reported in the scientific literature.An erratum to this article can be found at     

Environmental Impacts of Diesel Fuel on Bacteria and Phytoplankton in a Tropical Estuary Assessed Using <Emphasis Type="BoldItalic">In Situ</Emphasis> Mesocosms.

Dissolved or dispersed petroleum hydrocarbon concentrations (DDPH) were monitored in Ponggol estuary, Singapore, fortnightly from July 1999 to June 2000. DDPH concentrations ranged from 4.4 to 248.9gl^–1 and 0.4 to 1099.7gl^–1 for surface and subsurface waters, respectively and with mean concentrations of 41.01gl^–1 in the water column. Absorbed or adsorbed petroleum hydrocarbon (AAPH) concentrations measured in sediments ranged from 20.6 to 541.0 mg kg^–1, with mean concentrations of 148.23 mgkg^–1. In situ mesocosm studies of bacteria and phytoplankton were based on field monitoring ofenvironmentally measured concentrations of petroleum hydrocarbons, using diesel fuel as the source of contaminant. The mesocosm comprised of 25 L clear polycarbonate carboys incubated in situ for 6 days. Water and sediments from a clean site with undetectable levels of petroleum hydrocarbons were used in controls. The treatment mesocosms comprised of mean and highest concentrations of DDPH and AAPH. The study revealed signs of acute toxicity to autotrophs viz., phytoplankton and autotrophic bacteria in treatments simulating concentrations of diesel fuel found in the sediments. A stimulatory effect was seen at lower concentrations. Bacterial heterotrophs responded positively to all concentrations of diesel fuel because of the abundance of a carbon source, reduced grazing pressure and reduced competition for nutrients from phytoplankton.     

Withdrawal symptom after discontinuation of transdermal fentanyl at a daily dose of 0.6 mg

Neurophysiologic disorders developed in three patients after discontinuation of transdermal fentanyl (TDF) at a daily dose of 0.6mg (2.5mg per a patch), although direct removal of a 2.5mg patch is permitted by the manufacturer as the formulation has the lowest fentanyl content among all the commercially available patch formulations. These observations indicate that the discontinuation of TDF carries a risk for developing withdrawal symptoms even when using a 2.5mg patch. To avoid such adverse events, we considered the necessity of gradual reduction in the daily fentanyl requirements. For this purpose, we covered part of the application surface of the patch with an insulating tape, and then increased the covered area in a stepwise manner. There were no apparent withdrawal signs during the procedure described above.     

Measuring cytochrome P450 activity in aquatic invertebrates: a critical evaluation of in vitro and in vivo methods

The first step in xenobiotic detoxification in aquatic invertebrates is mainly governed by the cytochrome P450 mixed function oxidase system. The ability to measure cytochrome P450 activity provides an important tool to understand macroinvertebrates’ responses to chemical stressors. However, measurements of P450 activity in small aquatic invertebrates have had variable success and a well characterized assay is not yet available. The general lack of success has been scarcely investigated and it is therefore the focus of the present work. In particular, the suitability of the substrate selected for the assay, the sensitivity of the assay and the possible inhibition/attenuation of enzymatic activity caused by endogenous substances were investigated. 7-ethoxycoumarin-O-dealkylation activity of Daphnia magna, Chironomus riparius larvae and Hyalella azteca was assessed in vivo and in vitro and possible inhibition of enzymatic activity by macroinvertebrates homogenate was investigated. Activities of D. magna and C. riparius larvae measured in vivo were 1.37 ± 0.08 and 2.2 ± 0.2 pmol h^?1 organism^?1, respectively, while activity of H. azteca could not be detected. In vitro activity could be measured in C. riparius larvae only (500–1000 pmol h^?1 mg microsomal protein^?1). The optimization of the in vitro assay has been especially long and resource consuming and particularly for D. magna, substances that inhibited cytochrome P450 activity seemed to be released during tissue homogenization preventing activity measurements in vitro. We therefore recommend testing the P450 inhibition potential of homogenate preparations prior to any investigation of P450 activity in vitro in macroinvertebrates.     

Evaluation of Cytotoxicity of Various Ophthalmic Drugs, Eye Drop Excipients and Cyclodextrins in an Immortalized Human Corneal Epithelial Cell Line

Purpose. An immortalized human corneal epithelial cell line (HCE) was tested as a screening tool for prediction of topical ocular irritation/ toxicity by pharmaceuticals. Methods. Effects of various drugs, excipients and cyclodextrins (CDs) on viability of HCE cells were evaluated using two in vitrocytotoxicity tests, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) dye reduction assay and propidium iodide assay. Results. Mitochondrion-based MTT test was a more sensitive indicator of cytotoxicity than the plasma membrane-based propidium iodide test. The tests revealed following cytotoxic rankings for ophthalmic drugs: dipivefrin > timolol > pilocarpine dexamethasone; for excipients: benzalkonium chloride (BAC) > sodium edetate (NA₂EDTA) > poly-vinyl alcohol (PVA) > methylparaben; and for CDs: -CD > dimethyl--cyclodextrin (DM--CD) > sulfobutyl ether (-cyclodextrin ((SBE)_7m--CD) hydroxypropyl--cyclodextrin (HP--CD) > -CD. In consideration of the in vivoclinical situation, the short exposure time (5 min) is more relevant even though toxic effects of some test substances were seen only after longer exposure times (30 and 60 min). Conclusions. Immortalized HCE cells are a promising tool for rapid cytotoxicity assays of ocular medications. The cell line is potentially useful in predicting the in vivocorneal toxicity of ocularly applied compounds.     

Different effects of vinblastine on the polymerization of isotypically purified tubulins from bovine brain

Vinblastine, a highly successful antitumor drug, targets the tubulin molecule. Tubulin, the subunit protein of microtubules, consists of an - and a -subunit, both of which consist of isotypes encoded by different genes. We have purified three isotypes of bovine brain tubulin, namely, _II, _III and _IV. Microtubule associated protein-2 (MAP2) and Tau-induced assembly of these isotypes were compared in the presence and absence of vinblastine. MAP2-induced assembly of unfractionated tubulin and all the isotypes except _II tubulin was resistant to 1M vinblastine. Vinblastine at low concentrations (<10M) progressively inhibited the assembly of all of the isotypes but the vinblastine concentration required for inhibition of MAP2-induced microtubule assembly was minimal for _II. The tau-induced assembly of unfractionated tubulin and _III were equally sensitive to 1M vinblastine whereas _II and _IV were much more sensitive to vinblastine. The microtubules obtained in the presence of tau from unfractionated tubulin, _II and _IV could be easily aggregated by 20M vinblastine whereas such as aggregation of microtubules obtained from _III and tau required approximatedly 40M vinblastine. Our results suggest that among the tubulin isotypes, _II is the most sensitive to vinblastine in the presence of MAPs while _III is the most resistant and this intrinsic resistance of _III dimers persists in the polymeric form of _III tubulin as well. These results may be relevant to the therapeutic and toxic actions of vinblastine.     

Population Genetic Structure of the Western Mosquitofish,Gambusia Affinis,In a Highly Channelized Portion of the San Antonio River in San Antonio,TX

Population genetic assessments were performed on populations of the mosquitofish, Gambusia affinis, sampled at seven sites along a 10km reach of the upper San Antonio River in San Antonio, TX. Mosquitofish populations were sampled from the downtown area, known as the Riverwalk, where the river is concrete lined, deeply pooled, and receives heavy tour boat traffic. Populations were also sampled from sites upstream and downstream from the Riverwalk. Allozyme electrophoresis was performed on approximately 50 individuals from each site. Five of 12 loci surveyed were polymorphic (95% criterion). Exact tests over all loci for all populations indicated that allele frequencies differed significantly among sites. Allele frequencies of the upstream population were significantly different from the Riverwalk populations. Differences resulted primarily from significant decreases in frequencies of rare alleles at MDH-2* and two GPI* loci in the downtown area. Mean dissolved oxygen measurements were also significantly lower at Riverwalk sites. These results suggest that selective forces such as non-point source runoff or low dissolved oxygen, perhaps in combination with limited migration due to numerous dams, have reduced genetic diversity of populations in the downtown area.     

Toxicity and EROD-inducing potency of 24 polycyclic aromatic hydrocarbons (PAHs) in chick embryos

The toxicities (embryolethality) of 24 polycyclic aromatic hydrocarbons (PAHs) were determined in chick embryos using a 72-h test. The substances, dissolved in peanut oil, were injected into the air sacs of eggs preincubated for 7 days. LD₅₀ values were determined for the four most toxic of the 24 compounds. Benzo [k] fluoranthene proved to be the most potent, with an LD₅₀ of 14 g (56 nmol)/kg egg. Dibenz[a,h]anthracene, benz[a]anthracene and benzo[b]naphtho[2,3-d]thiophene were a few times less toxic [LD₅₀=39 g (140 nmol)/kg, 79 g (349 nmol)/kg and 82 g (350 nmol)/kg, respectively]. The LD₅₀ of benzo [k] fluoranthene was only about 5 times higher than that previously found for the most potent coplanar polychlorinated biphenyl (PCB), 3,3,4,4,5-pentachlorobiphenyl [LD₅₀=3.1 g (9.4 nmol)/kg], in the same kind of test. The toxicities of 18 of the PAHs in this study have also been evaluated previously using a 2-week test in chick embryos. Dibenz[a,h]anthracene, which had not been studied earlier in the 2-week test, proved to be almost as toxic as previously found for benzo [k] fluoranthene in that test. Several of the PAHs studied induced EROD activity in chick embryos, and, in general, the most toxic PAHs were also the most potent inducers of EROD. The highest enzyme activities were found after treatment with indeno[1,2,3-c,d]pyrene (12 times the control value) and dibenz[a,h]anthracene (8 times the control value). However, due to the high toxicity of dibenz[a,h]anthracene, the dose used was 7 times lower than that of indeno [1,2,3-c,d]pyrene. Following injection of PAHs on day 7, the EROD activities on day 10 were considerably lower than those obtained after a corresponding treatment with coplanar PCBs in an earlier study. Of the PAHs studied, some exhibited very high embryotoxicity. The most toxic PAHs induced EROD activity, suggesting that their toxicity was at least partly mediated via binding to the Ah receptor.     

Phase II trial of antiepidermal growth factor receptor antibody C225 in patients with advanced renal cell carcinoma

Fifty-five patients with metastatic renal cell carcinoma (RCC) were treated on a multicenter, single-arm Phase II trial. Patients received single-agent Cetuximab (C225) administered by intravenous infusion at a loading dose of 400 or 500mg/m² followed by weekly maintenance doses at 250mg/m². None of the patients treated with C225 achieved either a complete or partial response. The median time to progression was 57 days. The most frequently reported grade 3 or 4 toxicity treatment-related adverse events were acne (17%) and rash or dry skin (4%). The lack of clinical response or suggestion of prolonging time to progression compared to historical data with interferon-alfa supports no further study of single-agent C225 in patients with metastatic RCC.     

Hazard Assessment of Resmethrin: I. Effects and Fate in Aquatic Systems

A comparative aquatic hazard assessment of resmethrin was conducted to investigate the need for its restricted use classification by the US. EPA as an adult mosquito control agent. This paper describes the environmental fate and aquatic toxicity of resmethrin. The following paper compares resmethrin to the alternative insecticides. Environmental fate studies indicate that resmethrin has a short photolytic half-life in water (< 1h). Furthermore, it is immobile in soil and biodegradable (half-life=36.5d) under aerobic conditions. Laboratory studies with constant 48- to 96-h exposures show it is acutely toxic to fish and invertebrates in the 0.22–15.0g/L range. Daphnia magna, pink shrimp (Penaeus duorarum) and rainbow trout (Oncorhynchus mykiss) are the most sensitive and mollusks are the least sensitive species. Chronic laboratory studies indicate that the maximum acceptable toxicant concentrations (MATCs) for resmethrin and D. magna, Pimephales promelas, O. mykiss, and Cyprinodon variegatus are 0.58, 0.52, 0.43, and 10.3g/L, respectively. The acute-to-chronic ratios (1.1–7.3) for all species studied indicate that chronic toxicity will not be an issue for resmethrin. Furthermore, the characteristics of acute exposures (48- to 96-h) used in the laboratory will not occur under field conditions because of the short half-life of resmethrin in fresh- and salt-water.     

QSAR of ecotoxicological data on the basis of data-driven if-then-rules

A rather small data matrix of seven chemicals and 17 different ecotoxicological end points is examined by methods of Discrete Mathematics. Especially, the lattice theory and its variant, the Formal Concept Analysis may be an attractive tool to analyze Quantitative Structure Activity Relationships, when a numerical functional approach is not at hand. The central item is the so called concept, which is a pair of subsets: A subset of molecules and a subset of properties which correspond to each other. The concepts are partially ordered due to a subset relation. From this subset relation, if–then-rules are derived, which aim to relate the structure of molecules with their ecotoxicological properties. For example, the following chemical rule is found: Cl (2A,2C,2M). That means, all substances considered here having a –Cl as structural code have a medium ecotoxicological effect on Daphnia magna , Orconectes immunisare (Crustacea) and on Photobacterium phosphoreum , at least within the training set.     

Responses of human bone marrow progenitor cells to fluoro-ara-AMP,homoharringtonine, and elliptinium

Summary The cytotoxicity of the investigational anticancer drugs fluoro-ara-AMP, homoharringtonine, and elliptinium on normal human granulocyte-macrophage colony-forming units in culture (GM-CFU) was investigated using a bilayer soft agar system. For each drug, the dose-dependent survival curve on a semilogarithmic plot formed a straight line. The Do were: 0.51 g/ml (fluoro-ara-AMP), 0.004 g/ml (homoharringtonine) and 0.026 g/ml (elliptinium). The in vitro toxicity of drugs on bone marrow progenitor cells did not correlate with the relative myelosuppressive potency observed in vivo.     

Usefulness of the Kohlrausch-Williams-Watts Stretched Exponential Function to Describe Protein Aggregation in Lyophilized Formulations and the Temperature Dependence Near the Glass Transition Temperature

Purpose. We studied the feasibility of using the Kohlrausch-Williams-Watts stretched exponential function (KWW equation) to describe protein aggregation in lyophilized formulations during storage. Parameters representing mean aggregation time (_a) and stretched exponential constant (_a) were calculated according to the KWW equation by assuming that the time required for protein molecules to aggregate () varies because of the fact that protein aggregation occurs at a rate that depends on the degree of protein deformation resulting from stresses created during freeze-drying. The temperature dependence of the parameters near the glass transition temperature was examined to discuss the possibility of predicting protein aggregation by accelerated testing. Methods. Protein aggregation in lyophilized bovine serum -globulin (BGG) formulations containing dextran or methylcellulose, at temperatures ranging from 10 to 80°C, was followed by size-exclusion chromatography. Results. Non-exponential BGG aggregation in lyophilized formulations could be described by the KWW equation. The _a and _a parameters changed abruptly around the NMR relaxation-based critical mobility temperature for formulations containing dextran and methylcellulose. In the glassy state, in contrast, the _a parameter of these formulations exhibited continuous temperature dependence. The parameter , as calculated from _a and _a, reflected differences in values between the two excipients. Conclusions. The results indicate that the parameter _a is reflective of physical changes wihtin lyophilized formulations. Within the temperature range, during which no abrupt changes in _a were observed, knowledge regarding the _aand _a parameters allows the rate of protein aggregation to be predicted. The parameter was found to be useful in comparing the protein aggregation behavior of formulations having different _a and _a values.