Preclinical Activity of 4-Demethyl-4-cholesteryloxycarbonylpenclomedine in Melanoma.

BACKGROUND/AIM: Temozolomide plays a role in treating melanoma refractory to immunomodulatory and mitogen-activated protein kinase-targeted approaches, but its efficacy is limited. 4-Demethyl-4-cholesteryloxycarbonylpenclomedine (DM-CHOC-PEN) is a polychlorinated pyridine cholesteryl carbonate. Its mechanism of action is considered to be via alkylation/adduct formation with N7-guanine. It demonstrated activity in intracranial implanted human glioma and breast cancer xenograft mouse models. The activity of DM-CHOC-PEN in melanoma models was assessed. MATERIAL AND METHODS: B-16 melanoma cells were exposed to DM-CHOC-PEN at different concentrations to assess proliferation and survival. B-16 cells were implanted subcutaneously into the flank of adult female C57BL mice which were then were treated with 200 mg/kg DM-CHOC-PEN intraperitoneally daily for 5 days in the setting of palpable subcutaneous tumor. Survival was compared to mice treated with temozolomide or saline. Five mice were treated per group. RESULTS: In vitro, the respective half-maximal inhibitory concentrations of DM-CHOC-PEN and temozolomide were 0.5 and ≥3.0 µg/ml. Floating, heavily melanotic cells formed and these cells were separated, analyzed, and contained 10-90 ng DM-CHOC-PEN per 105 cells. The improvement in survival of mice treated with DM-CHOC-PEN or temozolomide relative to saline controls was 142% and 78%, respectively. CONCLUSION: Longer survival was seen with DM-CHOC-PEN in a C57BL murine model relative to temozolomide and saline-treated controls, supporting the development of clinical trials assessing the efficacy of DM-CHOC-PEN as treatment for metastatic melanoma.

Thoracic Schwannoma in an Adult Male Presenting With Thoracic Pain: A Case Report.

OBJECTIVE: The purpose of this case report was to describe a patient presenting with back pain subsequently diagnosed with thoracic schwannoma. CLINICAL FEATURES: A 45-year-old male presented to a chiropractic practice with mid-back, low back, and sacroiliac pain. Orthopedic examination revealed joint dysfunction in the thoracic-sacroiliac region with normal findings on neurologic examination. An initial diagnosis of thoracic spinal pain and sacroiliac sprain and strain was made. At approximately 7 weeks of treatment, because of the patient's persistent pain, chest magnetic resonance imaging (MRI) was ordered by the chiropractic physician. INTERVENTIONS AND OUTCOMES: The chest MRI revealed an intradural extramedullary mass at the T5 level creating a marked compression of the spinal cord. A thoracic MRI was conducted 2 days later confirming the presence of the tumor. The patient was successfully treated with spinal surgery to remove a schwannoma. CONCLUSIONS: Mechanical spinal pain is a common symptom in patients presenting to chiropractic offices and may present concurrent with other pathology. In the presence of unresolved persistent thoracic pain, clinicians should investigate other potential causes.

Electrochemical Investigation of Adsorption of Single-Wall Carbon Nanotubes at a Liquid/Liquid Interface.

There is much interest in understanding the interfacial properties of carbon nanotubes, particularly at water/oil interfaces. Here, the adsorption of single-wall carbon nanotubes (SWCNTs) at the water/1,2-dichloroethane (DCE) interface, and the subsequent investigation of the influence of the adsorbed nanotube layer on interfacial ion transfer, is studied by using the voltammetric transfer of tetramethylammonium (TMA+) and hexafluorophosphate (PF6-) as probe ions. The presence of the interfacial SWCNT layer significantly suppresses the transfer of both ions across the interface, with a greater degree of selectivity towards the PF6- ion. This effect was attributed both to the partial blocking of the interface by the SWCNTs and to the potential dependant adsorption of background electrolyte ions on the surface of the SWCNTs, as confirmed by X-ray photoelectron spectroscopy, which is caused by an electrostatic interaction between the interfacial SWCNTs and the transferring ion.

Electrostatic Stabilization of Graphene in Organic Dispersions.

The exfoliation of graphite to give graphene dispersions in nonaqueous solvents is an important area with regards to scalable production of graphene in bulk quantities and its ultimate application in devices. Understanding the mechanisms governing the stability of these dispersions is therefore of both scientific interest and technological importance. Herein, we have used addition of an indifferent electrolyte to perturb few-layer graphene dispersions in a nonaqueous solvent (1,2-dichloroethane) as a way to probe the importance of interparticle electrostatic repulsions toward the overall dispersion stability. At a sufficient electrolyte concentration, complete sedimentation of the dispersions occurred over 24 h, and the relationship between dispersed graphene concentration and electrolyte concentration was consistent with a dispersion stabilized by electrostatic repulsions. We also found that an increased oxygen content in the graphite starting material produced dispersions of greater stability, indicating that the extent of oxidation is an important parameter in determining the extent of electrostatic stabilization in nonaqueous graphene dispersions.

Electron transfer kinetics on natural crystals of MoS2 and graphite.

Here, we evaluate the electrochemical performance of sparsely studied natural crystals of molybdenite and graphite, which have increasingly been used for fabrication of next generation monolayer molybdenum disulphide and graphene energy storage devices. Heterogeneous electron transfer kinetics of several redox mediators, including Fe(CN)6(3-/4-), Ru(NH3)6(3+/2+) and IrCl6(2-/3-) are determined using voltammetry in a micro-droplet cell. The kinetics on both materials are studied as a function of surface defectiveness, surface ageing, applied potential and illumination. We find that the basal planes of both natural MoS2 and graphite show significant electroactivity, but a large decrease in electron transfer kinetics is observed on atmosphere-aged surfaces in comparison to in situ freshly cleaved surfaces of both materials. This is attributed to surface oxidation and adsorption of airborne contaminants at the surface exposed to an ambient environment. In contrast to semimetallic graphite, the electrode kinetics on semiconducting MoS2 are strongly dependent on the surface illumination and applied potential. Furthermore, while visibly present defects/cracks do not significantly affect the response of graphite, the kinetics on MoS2 systematically accelerate with small increase in disorder. These findings have direct implications for use of MoS2 and graphene/graphite as electrode materials in electrochemistry-related applications.

A free-enzyme catalyst for the bioremediation of environmental atrazine contamination.

Herbicide contamination from agriculture is a major issue worldwide, and has been identified as a threat to freshwater and marine environments in the Great Barrier Reef World Heritage Area in Australia. The triazine herbicides are of particular concern because of potential adverse effects, both on photosynthetic organisms and upon vertebrate development. To date a number of bioremediation strategies have been proposed for triazine herbicides, but are unlikely to be implemented due to their reliance upon the release of genetically modified organisms. We propose an alternative strategy using a free-enzyme bioremediant, which is unconstrained by the issues surrounding the use of live organisms. Here we report an initial field trial with an enzyme-based product, demonstrating that the technology is technically capable of remediating water bodies contaminated with the most common triazine herbicide, atrazine.

Honeybee silk: recombinant protein production, assembly and fiber spinning.

Transgenic production of silkworm and spider silks as biomaterials has posed intrinsic problems due to the large size and repetitive nature of the silk proteins. In contrast the silk of honeybees (Apis mellifera) is composed of a family of four small and non-repetitive fibrous proteins. We report recombinant production and purification of the four full-length unmodified honeybee silk proteins in Escherichia coli at substantial yields of 0.2-2.5 g/L. Under the correct conditions the recombinant proteins self-assembled to reproduce the native coiled coil structure. Using a simple biomimetic spinning system we could fabricate recombinant silk fibers that replicated the tensile strength of the native material.

Carbonate and carbamate derivatives of 4-demethylpenclomedine as novel anticancer agents.

PURPOSE: The purpose of this investigation was to synthesize a series of carbonate and carbamate derivatives of 4-demethylpenclomedine (DM-PEN), the major plasma non-toxic metabolite of penclomedine (PEN) seen in patients. DM-PEN has been observed to be an active antitumor agent in mouse human xenograft tumor models and non-neurotoxic in a rat model, however, activity in intracranially implanted human glioma xenograft models have not been reported. The major goal was to identify derivatives that are active in brain tumors. METHODS: Derivatives were prepared from DM-PEN and evaluated in vivo against human U251 glioblastoma, D54 glioblastoma and MX-1 breast tumor xenografts and mammary tumor 16/C that were implanted in the mammary fat pad or intracranially (IC). RESULTS: Carbonate and carbamate derivatives were found to be superior to DM-PEN against IC growing human glioblastoma xenografts. CONCLUSION: The activity of the carbonates and carbamates against human tumor xenografts in vivo suggests consideration of these two series of derivatives of DM-PEN for clinical development.

The structure and function of mitochondrial F1F0-ATP synthases.

We review recent advances in understanding of the structure of the F(1)F(0)-ATP synthase of the mitochondrial inner membrane (mtATPase). A significant achievement has been the determination of the structure of the principal peripheral or stator stalk components bringing us closer to achieving the Holy Grail of a complete 3D structure for the complex. A major focus of the field in recent years has been to understand the physiological significance of dimers or other oligomer forms of mtATPase recoverable from membranes and their relationship to the structure of the cristae of the inner mitochondrial membrane. In addition, the association of mtATPase with other membrane proteins has been described and suggests that further levels of functional organization need to be considered. Many reports in recent years have concerned the location and function of ATP synthase complexes or its component subunits on the external surface of the plasma membrane. We consider whether the evidence supports complete complexes being located on the cell surface, the biogenesis of such complexes, and aspects of function especially related to the structure of mtATPase.

4,4'-Dihydroxybenzophenone-2,4-dinitrophenylhydrazone (A-007): a topical treatment for cutaneous metastases from malignant cancers.

PURPOSE: This study is to document the activity and acceptability for a new topical agent, A-007, in the treatment of cutaneous metastases from cancer. PATIENTS AND METHODS: This is a multicenter study involving 27 patients with inoperable skin lesions from histologically confirmed cancers of the breast and oral cavity, non-Hodgkin's lymphoma, Kaposi's sarcoma, and angiosarcoma that had failed radiotherapy or systemic treatment. A-007, as a 0.25% gel, was applied twice daily to the areas of cancer to be measured as well as applied to a healthy control area distant from the cancer areas. An untreated cancer area was also included and documented as a cancer control. RESULTS: The overall objected response rate with A-007 was 26%, with an additional 19% minimum response/stabilization of cancer. For patients with breast cancer, hormonal status did not have an impact on response. The median duration of response was 15 weeks (with one patient having a response for 3.5 years). Toxicities observed were itching, burning, and a rash, in 6 of the 27 patients. The skin toxicities were in the cancer-treated fields; none were observed in the A-007 control areas. All irritated areas cleared while continuing treatment, and the tumor lesions in the areas of itching also improved. CONCLUSION: A-007, as a 0.25% gel, is confirmed as an effective palliative treatment option for cutaneous metastases from cancers. Skin reactions were minimal, tolerated, and no cessation of treatment was required.

Comparative preclinical toxicology and pharmacology of isophosphoramide mustard, the active metabolite of ifosfamide.

BACKGROUND: Isophosphoramide mustard (IPM) is the cytotoxic alkylating metabolite of Ifosfamide (IFOS). IPM is being readied for a phase I clinical trial. In the present preclinical study, IPM was evaluated for usage in multidose intravenous (IV) infusion protocols. METHODS: Mice and dogs received IV IPM daily for 3 days. Single-day dosing-oral and IV-to mice, rats, and monkeys is also reviewed for comparison. Complete toxicology studies were completed in the mice and dogs. For mice, dogs and monkeys, IV pharmacokinetic studies were conducted and compared. RESULTS: For mice, the LD(10) for the 3-day IV schedule for IPM was calculated to be 119 mg/kg (with 95% confidence limits of 87-134 mg/kg) (combined sexes), and for adult male dogs the maximum tolerated dose (MTD) was 5 mg/kg. Pharmacokinetic studies in mice, dogs and monkeys were compared and projected to human dosing. For dogs that received 10 mg/kg of IPM, T(1/2beta) was 0.99 h, and clearance was constant (1.01 l/h/kg). IPM was detected from 0 h to 1.5 h after the 5 mg/kg dose and from 0 h to 2 h after the 10 mg/kg dose; none was detected after 2 h. The IV MTD in dogs was 5 mg/kg per day for 3 days. Renal tubular necrosis and bone marrow failure were the causes of death. Transient liver, renal and bone marrow toxicity and gastrointestinal dysfunction were seen at low doses (<5 mg/kg) in dogs. In mice (receiving 100 mg/kg IV) plasma concentrations disappeared in less than 1 h (T(1/2alpha) 2 min), with a clearance of 8.44 l/h/kg. For monkeys, the mean T(1/2) was 4.2 h. Median clearance was 1.65 l/h/kg and no IPM was detected 4 h after dosing. No potential IPM metabolites could be detected in any of the studies. In vitro, plasma protein bound 90% of IPM within 5 min of incubation. CONCLUSIONS: Predictions for human pharmacokinetic parameters and dosing are made from allometric analysis using the above three species. Data predicted an acceptable starting dose of 30 mg/m(2) with a clearance of 39.5 l/h, and a T(1/2) of 1 h 45 min for a 70-kg patient.

Design, synthesis, and anticancer properties of 4,4'-dihydroxybenzophenone-2,4-dinitrophenylhydrazone and analogues.

4,4'-dihydroxybenzophenone-2,4-dinitrophenylhydrazone (A-007) has recently completed a phase I clinical trial in advanced cancer with minimal toxicity, and impressive objective responses were noted. A-007 possesses three moieties that appear to have an influence on its anticancer activities: diphenylmethane, hydrazone, and dinitrophenyl. The goals of this study were to modify A-007's chemical moieties with the ultimate goal of maximizing its anticancer activity through increased planarity and introduction of functional groups. Thirty-five phenylhydrazone analogues of A-007 were synthesized and evaluated in vitro in a human primary cancer explant assay. Anticancer activities for selected analogues were also assayed for activity vs established human/murine cell lines. One-hundred-eighty-six fresh human solid tumors were used to screen for anticancer activity. Selected analogues were assayed for therapeutic indices (vs GM-CFC from bone marrow) in preparation for preclinical studies. Several polyaryl phenylhydrazones demonstrated improved cytotoxic activities by factors of 10(2)-10(3) when compared with A-007. However, the polyaryl quinone moieties of the latter analogues introduced potential toxic properties (cardiac, hematological) that do not exist with A-007.