Real-Time Measurement of Nanotube Resonator Fluctuations in an Electron Microscope.

Mechanical resonators based on low-dimensional materials provide a unique platform for exploring a broad range of physical phenomena. The mechanical vibrational states are indeed extremely sensitive to charges, spins, photons, and adsorbed masses. However, the roadblock is often the readout of the resonator, because the detection of the vibrational states becomes increasingly difficult for smaller resonators. Here, we report an unprecedentedly sensitive method to detect nanotube resonators with effective masses in the 10-20 kg range. We use the beam of an electron microscope to resolve the mechanical fluctuations of a nanotube in real-time for the first time. We obtain full access to the thermally driven Brownian motion of the resonator, both in space and time domains. Our results establish the viability of carbon nanotube resonator technology at room temperature and pave the way toward the observation of novel thermodynamics regimes and quantum effects in nanomechanics.

Ordered arrays of Au catalysts by FIB assisted heterogeneous dewetting.

Synthesizing Au0.8Si0.2 nanocatalysts that are homogeneous in size and have controlled position is becoming a challenging and crucial prequisite for the fabrication of ordered semiconductor nanowires. In this study, Au0.8Si0.2 nanocatalysts are synthesized via dewetting of Au layers on Si(111) during thermal annealing in an ultra-high vacuum. In the first part of the paper, the mechanism of homogeneous dewetting is analyzed as a function of the Au-deposited thickness (h Au). We distinguish three different dewetting regimes: (I) for a low thickness ([Formula: see text]), a submonolyer coverage of Au is stabilized and there is no dewetting. (II) For an intermediate thickness ([Formula: see text]), there is both dewetting and Au0.8Si0.2 phase formation. The size and density of the Au0.8Si0.2 clusters are directly related to h Au. When cooling down to room temperature, the clusters decompose and reject the Si at the Au/Si substrate interface. (III) For a large thickness ([Formula: see text]), only dewetting takes place, without forming AuSi clusters. In this regime, the dewetting is kinetically controlled by the self-diffusion of Au (activation energy ∼0.43 eV) without evidence of an Si-alloying effect. As a practical consequence, when relying solely on the homogeneous dewetting of Au/Si(111) to form the Au0.8Si0.2 catalysts (without a supply of Si atoms from vapor), regime II should be used to obtain good size and density control. In the second part of the paper, a process for ordering the catalysts using focused ion beam-(FIB) assisted dewetting (heterogeneous dewetting) is developed. We show that no matter what the FIB milling conditions and the Au nominal thickness are, dewetting is promoted by ion beam irradiation and is accompanied by the formation of Au0.8Si0.2 droplets. The droplets preferentially form on the patterned areas, while in similar annealing conditions, they do not form on the unpatterned areas. This behavior is attributed to the larger Au-Si interdiffusion in the patterned areas, which results from the Si amorphization induced by the FIB. A systematic analysis of the position of the nanodroplets shows their preferential nucleation inside the patterns, while thicker platelets of almost pure Au are observed between the patterns. The evolutions of the size homogeneity and the occupancy rate of the patterns are quantified as a function of the FIB dose and annealing temperature. Nice arrays of perfectly ordered AuSi catalysts are obtained after optimizing the FIB and dewetting conditions.

Monitoring the kinetic evolution of self-assembled SiGe islands grown by Ge surface thermal diffusion from a local source.

In this paper we experimentally study the growth of self-assembled SiGe islands formed on Si(001) by exploiting the thermally activated surface diffusion of Ge atoms from a local Ge source stripe in the temperature range 600-700 °C. This new growth strategy allows us to vary continuously the Ge coverage from 8 to 0 monolayers as the distance from the source increases, and thus enables the investigation of the island growth over a wide range of dynamical regimes at the same time, providing a unique birds eye view of the factors governing the growth process and the dominant mechanism for the mass collection by a critical nucleus. Our results give experimental evidence that the nucleation process evolves within a diffusion limited regime. At a given annealing temperature, we find that the nucleation density depends only on the kinetics of the Ge surface diffusion resulting in a universal scaling distribution depending only on the Ge coverage. An analytical model is able to reproduce quantitatively the trend of the island density. Following the nucleation, the growth process appears to be driven mainly by short-range interactions between an island and the atoms diffusing within its vicinities. The islands volume distribution is, in fact, well described in the whole range of parameters by the Mulheran's capture zone model. The complex growth mechanism leads to a strong intermixing of Si and Ge within the island volume. Our growth strategy allows us to directly investigate the correlation between the Si incorporation and the Ge coverage in the same experimental conditions: higher intermixing is found for lower Ge coverage. This confirms that, besides the Ge gathering from the surface, also the Si incorporation from the substrate is driven by the diffusion kinetics, thus imposing a strict constraint on the initial Ge coverage, its diffusion properties and the final island volume.

Universal distance-scaling of nonradiative energy transfer to graphene.

The near-field interaction between fluorescent emitters and graphene exhibits rich physics associated with local dipole-induced electromagnetic fields that are strongly enhanced due to the unique properties of graphene. Here, we measure emitter lifetimes as a function of emitter-graphene distance d, and find agreement with a universal scaling law, governed by the fine-structure constant. The observed energy transfer rate is in agreement with a 1/d(4) dependence that is characteristic of two-dimensional lossy media. The emitter decay rate is enhanced 90 times (energy transfer efficiency of ~99%) with respect to the decay in vacuum at distances d ≈ 5 nm. This high energy transfer rate is mainly due to the two-dimensionality and gapless character of the monatomic carbon layer. Graphene is thus shown to be an extraordinary energy sink, holding great potential for photodetection, energy harvesting, and nanophotonics.

Uranium disequilibrium in groundwater: an isotope dilution approach in hydrologic investigations.

The distribution and environmental disequilibrium patterns of naturally occurring uranium isotopes (U(234) and U(238)) in waters of the Floridan aquifer suggest that variations in the ratios of isotopic activity and concentrations can be used quantitatively to evaluate mixing proportions of waters from differing sources. Uranium is probably unique in its potential for this approach, which seems to have general usefulness in hydrologic investigations.

Microbicides for multidrug-resistant and multitropic HIV-1.

The most common mode of acquiring HIV-1 is via sexual transmission across the genital mucosa. Topical microbicides are a promising prevention strategy for the protection against HIV infection and may ultimately have an impact on the global AIDS pandemic. The effectiveness of a microbicide to prevent HIV-1 transmission will depend on the evolutionary and genital transmission dynamics of the viral subtypes, and sexual behavioral characteristics. Contemporary antiretroviral therapy has led to virological failure as a result of HIV-1 reverse transcriptase gene mutations. The transmission of these multidrug-resistant HIV-1 variants, and the superinfection with the same or distinct HIV-1 subtypes and recombination is a formidable hindrance inherent to global microbicide development. Consequently, mechanism-based microbicides targeting both the cell-free and cell-associated HIV-1 variants and subtypes can be expected to have superior clinical efficacy and safety profiles compared with polymeric anionic microbicides. This review describes the discovery of potent anti-HIV-1 agents against multidrug-resistant and multitropic HIV-1 variants with implications for global microbicide development. Stampidine and thiourea non-nucleoside reverse transcriptase inhibitors (NNRTIs) have demonstrated highly potent activity against clinically relevant multidrug-resistant and recombinant HIV-1 isolates spanning different subtypes across several continents. Extensive preclinical studies have shown that stampidine and a candidate thiourea NNRTI (HI-443) have clinical potential as a safe combination microbicide to inhibit, prevent or treat mucosal HIV-1 infections.

An investigation into the use of CMOS active pixel technology in image-guided radiotherapy.

The increased intelligence, read-out speed, radiation hardness and potential large size of CMOS active pixel sensors (APS) gives them a potential advantage over systems currently used for verification of complex treatments such as IMRT and the tracking of moving tumours. The aim of this work is to investigate the feasibility of using an APS-based system to image the megavoltage treatment beam produced by a linear accelerator (Linac), and to demonstrate the logic which may ultimately be incorporated into future sensor and FPGA design to evaluate treatment and track motion. A CMOS APS was developed by the MI(3) consortium and incorporated into a megavoltage imaging system using the standard lens and mirror configuration employed in camera-based EPIDs. The ability to resolve anatomical structure was evaluated using an Alderson RANDO head phantom, resolution evaluated using a quality control (QC3) phantom and contrast using an in-house developed phantom. A complex intensity-modulated radiotherapy (IMRT) treatment was imaged and two algorithms were used to determine the field-area and delivered dose, and the position of multi-leaf collimator (MLC) leaves off-line. Results were compared with prediction from the prescription and found to agree within a single image frame time for dose delivery and 0.02-0.03 cm for the position of collimator leaves. Such a system therefore shows potential as the basis for an on-line verification system capable of treatment verification and monitoring patient motion.

Impact of targeting transforming growth factor ß-2 with antisense OT-101 on the cytokine and chemokine profile in patients with advanced pancreatic cancer.

BACKGROUND: Overexpression of the cytokine - transforming growth factor-beta 2 (TGF-ß2) - has been implicated in the malignant progression of pancreatic cancer (PAC). OT-101 (trabedersen) is an antisense oligodeoxynucleotide designed to target the human TGF-ß2 mRNA. In a Phase I/II study, OT-101 treatment with subsequent chemotherapy was characterized by outstanding overall survival (OS) in patients with PAC. OBJECTIVE: This study sought to identify 1) co-regulated sets of cyto-/chemokines; 2) potential mechanisms that link TGF-ß receptor type 2 receptor inhibition that may result in the induction of a cytokine storm; and 3) predictive biomarkers for OS outcome in OT-101-treated patients with PAC. MATERIALS AND METHODS: Plasma levels of 31 cyto-/chemokines were tracked over three cycles of OT-101 therapy (140 mg/m2/day) in 12 PAC patients. Samples were acquired before onset of OT-101 therapy and at eight selected time points during therapy. A mixed ANCOVA model was developed for 19 cyto-/chemokines with median expression >1 following OT-101 therapy. Regression and hierarchical clustering analyses were performed to identify correlated expressions in each patient across cyto-/chemokines or in each cyto-/chemokine across patients. Plasma cyto-/chemokine levels were compared with OS with and without subsequent chemotherapy. RESULTS: Three highly correlated subsets of cyto-/chemokines (Cluster 1: EGF, MIP-1α, MIP-1ß; Cluster 2: FGF-2, MIG, IP-10, IL-15, IFN-α, IL-12; and Cluster 3: HGF, IL-6, IL-8) were identified following OT-101 therapy. Suppression of TGF-ß signaling by OT-101 led to upregulation of IL-8, IL-15, IP-10, and HGF. Protein-protein interaction networks constructed using STRING10 algorithm identified a relationship between IL-8, IL-15, and TGF-ß receptor type 2 inhibition. The mixed analysis of covariance model that examined the levels of 19 cyto-/chemokines with OS as the covariate at each of the time points resulted in IL-8 and IL-15 exhibiting a significant association with OS during Cycle 1 of therapy. In the whole-blood culture model, the cytokines with the most pronounced increase after OT-101 treatment were IL-1ß, IL-8, and MCP-1. CONCLUSION: No consistent responses in cyto-/chemokine levels were observed due to OT-101 treatment. Levels of IL-8 and IL-15 during Cycle 1 were positively associated with OS across 12 patients with PAC and served as potential biomarkers for treatment outcome following OT-101 therapy.

Novel broad-spectrum thiourea non-nucleoside inhibitors for the prevention of mucosal HIV transmission.

Non-nucleoside inhibitors of HIV-1 reverse transcriptase (NNRTI) are an integral part of combination therapy comprising three classes of antiretroviral drugs for the management of HIV/AIDS. NNRTIs are chemically diverse compounds that bind to a common allosteric site of HIV-1 RT and noncompetitively inhibit DNA polymerization. Resistance to NNRTIs arises rapidly upon drug treatment and results from mutation of the amino acids lining the HIV-1 RT binding pocket. Nevertheless, rationally designed NNRTIs deduced from changes in binding pocket size, shape, and residue character that result from clinically observed NNRTI resistance mutations exhibit broad-spectrum anti-HIV-1 activity. Notably, membrane permeable tight binding NNRTIs have utility as topical microbicides since they are capable of blocking cell-free and cell-associated mucosal HIV-1 infection without metabolic activation. This review summarizes the discovery of highly potent tight binding phenethyl-thiazolyl-thiourea (PETT) derivatives targeting the NNI binding pocket of HIV-1 RT. These NNRTIs were rationally designed by molecular docking using a composite binding pocket constructed by superimposing the crystal structure coordinate data of several NNI/RT ligand-binding site complexes. Molecular modeling and score functions such as molecular surface area, the buried surface, and binding affinity values were used to analyze how drug-resistant mutations would change the RT binding pocket shape, volume, and chemical make-up of these NNRTIs, and how these changes could affect drug binding. Several ligand derivatization sites were identified for docked compounds that fit the binding pocket. The best fit was determined by calculating an inhibition constant (Ludi Ki) of the docked compound for the composite binding pocket. Compounds with a Ludi Ki of <1 microM were identified as the most promising tight binding NNRTIs. This review highlights novel lipophilic thiourea NNRTIs that display high binding affinity and selective indices with robust anti-HIV-1 activity against the wild type as well as drug-resistant isolates carrying multiple RT gene mutations. The increasing prevalence of drug-escape mutants among recent HIV seroconverters makes the discovery of these broad-spectrum thiourea NNRTIs useful as a component of topical microbicide for the prevention of mucosal HIV transmission.

Influence of long-term stability conditions on microbicidal nucleoside prodrug (WHI-07)-loaded gel-microemulsion.

The objective of this study was to evaluate the long-term stability of the antiretroviral spermicide WHI-07 (5-bromo-6-methoxy-5,6-dihydro-3'-azidothymidine-5'-(p-bromophenyl)-methoxyalaninyl phosphate) in a polymer-based microemulsion. The recovery and stability of WHI-07 in gel-microemulsion was examined by a validated high-performance liquid chromatography (HPLC) method. The stability was examined over a period of 24 weeks at 3 controlled temperatures (4 degrees C, 25 degrees C, and 40 degrees C). The recovery of the prodrug from 0.5% to 2.0% WHI-07-loaded gel-microemulsion was 99.8%. HPLC analysis revealed that a 2% WHI-07-loaded gel-microemulsion stored at room temperature and cold temperatures for 24 weeks retained >90% of the prodrug, whereas those stored at 40 degrees C maintained 90% of initial WHI-07 for at least 10 weeks. The observed stability of WHI-07 in gel-microemulsion is of great importance for its widespread utility in various climatological conditions.

Vaginal contraceptive activity of a chelated vanadocene.

Bis(cyclopentadienyl) complexes of vanadium (IV) or vanadocenes are rapid and potent inhibitors of human sperm motility with potential as a new class of contraceptive agents. This study sought to determine the vaginal contraceptive activity of vanadocene dithiocarbamate (VDDTC), a stable vanadocene (IV)-chelated complex, using the standard rabbit model as well as the domestic pig as a physiologically relevant animal model for contraception. In experiment I, ovulating New Zealand White does in subgroups of eight were artificially inseminated (AI) with semen mixed with VDDTC (0.01-1 mM) or vehicle. In experiment II, ovulating does in subgroups of 18 were AI at 5 and 60 min after intravaginal application of a gel with and without 0.1% VDDTC or 2% nonoxynol-9 (N-9) (Gynol II, Ortho Pharmaceutical, Raritan, NJ), and allowed to complete term pregnancy. In experiment III, seven sexually mature Duroc gilts in standing estrus were AI with and without intravaginal application of 0.1% VDDTC gel microemulsion. Exposure of rabbit semen to VDDTC at the time of artificial insemination resulted in a dose-dependent reduction in fertility. Exposure of semen to 1 mM VDDTC led to complete inhibition of fertility as assessed by the number of embryos (control 49/94 vs. VDDTC-treated 0/117, p<.0001) or the percent embryos (52% vs. 0%, respectively) based on number of embryos to corpora lutea. Intravaginal administration of 0.1% VDDTC gel microemulsion or Gynol II prior to artificial insemination significantly inhibited term pregnancy rates (88% and 62% inhibition, respectively) when compared to control gel alone. Vanadocene dithiocarbamate gel microemulsion provided 80% inhibition of fertility even when insemination was delayed until 60 min after intravaginal application of VDDTC gel microemulsion. Rabbits that delivered litters despite intravaginal exposure of semen to VDDTC via gel microemulsion had healthy offsprings with no apparent perinatal repercussions. In domestic pigs, intravaginal applications of 0.1% VDDTC gel microemulsion prior to artificial insemination led to complete inhibition of fertility as assessed by the number of embryos (control 29/52 vs. VDDTC-treated 0/44, p<.0001) or the percent embryos (56% vs. 0%, respectively) based on the number of embryos to corpora lutea. These results suggest that VDDTC is a potent contraceptive agent in vivo. Intravaginal use of VDDTC via a gel microemulsion has clinical potential as a safe alternative to currently used detergent-type contraceptives.

Uranium-series disequilibria as a means to study recent migration of uranium in a sandstone-hosted uranium deposit, NW China.

Uranium concentration and alpha specific activities of uranium decay series nuclides (234)U, (238)U, (230)Th, (232)Th and (226)Ra were measured for 16 oxidized host sandstone samples, 36 oxic-anoxic (mineralized) sandstone samples and three unaltered primary sandstone samples collected from the Shihongtan deposit. The results show that most of the ores and host sandstones have close to secular equilibrium alpha activity ratios for (234)U/(238)U, (230)Th/(238)U, (230)Th/(234)U and (226)Ra/(230)Th, indicating that intensive groundwater-rock/ore interaction and uranium migration have not taken place in the deposit during the last 1.0 Ma. However, some of the old uranium ore bodies have locally undergone leaching in the oxidizing environment during the past 300 ka to 1.0 Ma or to the present, and a number of new U ore bodies have grown in the oxic-anoxic transition (mineralized) subzone during the past 1.0 Ma. Locally, uranium leaching has taken place during the past 300 ka to 1.0 Ma, and perhaps is still going on now in some sandstones of the oxidizing subzone. However, uranium accumulation has locally occurred in some sandstones of the oxidizing environment during the past 1 ka to 1.0 Ma, which may be attributed to adsorption of U(VI) by clays contained in oxidized sandstones. A recent accumulation of uranium has locally taken place within the unaltered sandstones of the primary subzone close to the oxic-anoxic transition environment during the past 300 ka to 1.0 Ma. Results from the present study also indicate that uranium-series disequilibrium is an important tool to trace recent migration of uranium occurring in sandstone-hosted U deposits during the past 1.0 Ma and to distinguish the oxidation-reduction boundary.

Conceival, a novel noncontraceptive vaginal vehicle for lipophilic microbicides.

The objective of this study was to develop a nontoxic and noncontraceptive vaginal drug delivery vehicle for lipophilic anti-human immunodeficiency virus (HIV) microbicides. Three representative poorly water-soluble novel broad-spectrum anti-HIV microbicides, PHI-113, PHI-346, and PHI-443, were evaluated in 11 different solvent systems. Based on their solubility profiles, a novel nonspermicidal self-emulsifying gel (viz Conceival) composed of pharmaceutical excipients, sorbitol, polyethylene glycol 400, polysorbate 80, microcrystalline cellulose, xanthan gum, and water was optimized. Conceival enhanced the solubility of these poorly water-soluble (<0.001 mg/mL) anti-HIV drugs by at least 150- to 270-fold. Conceival was evaluated in vivo in the New Zealand white rabbit model for the preservation of sperm function based on pregnancy outcome and the potential for vaginal irritation following single and multiple intravaginal applications, respectively. Conceival administered intravaginally immediately prior to artificial insemination with semen had no adverse effects on subsequent reproductive performance, neonatal survival, or pup development when compared with untreated control group. Histologic evaluation of vaginal tissues of rabbits exposed intravaginally to Conceival for 14 consecutive days revealed lack of epithelial, submucosal, and vascular changes at the gel application site (total irritation score <3 out of a possible 16). These findings indicate that Conceival has potential to become a clinically useful, safe noncontraceptive vaginal vehicle for lipophilic microbicides.

Nanopatterned graphene on a polymer substrate by a direct peel-off technique.

A graphene (Gr) on a polyimide (PI) polymer film (Gr-PI film), obtained by a direct peel-off technique, is proposed and investigated. Thanks to its high transparency, electrical conductivity, mechanical strength, and chemical durability, the Gr-PI film is an ideal substrate for flexible electronic and optoelectronic devices, including transistors, light-emitting diodes, and plasmonic antennas. It is obtained using a straightforward method. After spin coating and curing a PI film on Gr previously grown on Cu, one can separate the Gr-PI film from the Cu foil thanks to the difference in the adhesive energy between the Gr-Cu and Gr-PI interfaces. The resulting Gr-PI film shows an average electrical sheet resistance ranging from 520 to 860 Ω/sq and a very high optical transmission (>90%), which have allowed the demonstration of a transparent heater. The surface morphology of the Gr-PI film follows that of the Cu foil, with the latter maintaining its surface properties and allowing in this way its reuse in subsequent chemical vapor deposition growth. The method can also be applied to patterned Gr, as is demonstrated for nanosize ribbons with a width of a few tens of nanometers.

Recombinant human CD19L-sTRAIL effectively targets B cell precursor acute lymphoblastic leukemia.

Patients with B cell precursor acute lymphoblastic leukemia (BPL) respond well to chemotherapy at initial diagnosis; however, therapeutic options are limited for individuals with BPL who relapse. Almost all BPL cells express CD19, and we recently cloned the gene encoding a natural ligand of the human CD19 receptor (CD19L). We hypothesized that fusion of CD19L to the soluble extracellular domain of proapoptotic TNF-related apoptosis-inducing ligand (sTRAIL) would markedly enhance the potency of sTRAIL and specifically induce BPL cell apoptosis due to membrane anchoring of sTRAIL and simultaneous activation of the CD19 and TRAIL receptor (TRAIL-R) apoptosis signaling pathways. Here, we demonstrate that recombinant human CD19L-sTRAIL was substantially more potent than sTRAIL and induced apoptosis in primary leukemia cells taken directly from BPL patients. CD19L-sTRAIL effectively targeted and eliminated in vivo clonogenic BPL xenograft cells, even at femtomolar-picomolar concentrations. In mice, CD19L-sTRAIL exhibited a more favorable pharmacokinetic (PK) profile than sTRAIL and was nontoxic at doses ranging from 32 fmol/kg to 3.2 pmol/kg. CD19L-sTRAIL showed potent in vivo antileukemic activity in NOD/SCID mouse xenograft models of relapsed and chemotherapy-resistant BPL at nontoxic fmol/kg dose levels. Together, these results suggest that recombinant human CD19L-sTRAIL has clinical potential as a biotherapeutic agent against BPL.

Clinical development of microbicides for the prevention of HIV infection.

The HIV/AIDS pandemic continues its spread at a rate of over 15,000 new infections every day. Sexual transmission of HIV-1 is the dominant mode of this pandemic spread. For the first time since the disease emerged in the early 1980s, about half the 42 million people now living with HIV/AIDS worldwide are women. Worldwide, more than 90 percent of all adolescent and adult HIV infections have resulted from heterosexual intercourse. The "feminization" of the pandemic largely driven by the social, economic, and biological factors warrants urgent attention particularly for the adolescent female population. In the absence of an effective prophylactic anti-HIV therapy or vaccine, current efforts are aimed at developing intravaginal/intrarectal topical formulations of anti-HIV agents or microbicides to curb the mucosal and perinatal HIV transmission. Microbicides would provide protection by directly inactivating HIV or preventing HIV from attaching, entering or replicating in susceptible target cells as well as dissemination from target cells present in semen or the host cells that line the vaginal/rectal wall. Thus, ideally, anti-HIV microbicides should be capable of attacking HIV from different angles. In addition, a contraceptive microbicide could help prevent unintended pregnancies worldwide. To be a microbicide, these agents must be safe, effective following vaginal or rectal administration, and should cause minimal or no genital symptoms following long-term repeated usage. A safe and efficacious anti-HIV microbicide is not yet available despite the fact that more than 60 candidate agents have been identified to have in vitro activity against HIV, 18 of which have advanced to clinical testing. Targeting HIV entry has been a favored approach because it is the first step in the process of infection and several readily available anionic polymeric products seem to variably interfere with these processes are the primary candidates for potential microbicides. Formulations of some anionic polymeric antiviral agents have been tested at various doses and various durations for safety, tolerability, and acceptability in Phase I/II clinical trials (vaginal, rectal, or penile studies) in HIV-uninfected and/or HIV-infected populations. Current multicenter Phase I/II safety and Phase II/III efficacy studies that are being conducted or planned in different geographical locations by various special interest groups are designed for rapid clinical development of candidate products. The currently marketed detergent-type spermicide, nonoxynol-9 (N-9), has failed in Phase III clinical trials, due to the drug-induced formation of localized genital lesions that might in fact actually promote virus transmission. Alternative "first-generation" microbicides that have undergone Phase I/II safety and tolerability studies in HIV-uninfected and/or HIV-infected volunteers include polymeric viral fusion inhibitors (dextrin sulfate/Emmelle, carrageenans [PC-213, PC-503, PC-515/Carraguard], cellulose sulfate/Ushercell, polystyrene sulfonate, naphthalene sulfonate [PIC 024-4/PRO 2000/5], acidifying gel [Carbomer 974P/BufferGel], Lactobacillus (L. crispatus) suppository/CTV-05, detergent-type dual-function barriers [ACIDFORM, GEDA Plus, SURETE, Glyminox/C31G/Savvy, Invisible Condom], herbal extracts [Praneem], and viral replication inhibitors [PMPA/Tenofovir]. For majority of these products, no information is available regarding their long-term mucosal safety, carcinogenicity potential, bioavailability, or efficacy following their extended vaginal or rectal exposure. The irritative genitourinary symptoms reported for a number of these first-generation products in Phase I clinical trials implies that the "soft" preclinical endpoints for mucosal safety established for the use and development of vaginal spermicides may not be rigorous enough for vaginal and rectal microbicides because of the efficient sexual tra virus diversity, and genetic environment. It is now apparent that sexually transmitted R5 HIV-1 viruses have less positive charge on their surface compared with the R4 HIV-1 viruses, which may limit the anionic polymers as topical microbicides despite extensive clinical trials. Nevertheless, their ongoing clinical trials, reviewed here, using optimized formulations, and special populations in various geographic locations are paving the way for future rigorous clinical testing of "mechanism-based" broad-spectrum anti-HIV microbicides that are currently under intense development. It is anticipated that future microbicide trials will focus on combination of products capable of attacking HIV life cycle at multiple steps intended to increase efficacy, limit cross-resistance as well as minimize microbicide-induced host toxicity.

Metvan: a novel oxovanadium(IV) complex with broad spectrum anticancer activity.

Among the 25 bis(cyclopentadienyl)vanadium(IV) and 14 oxovanadium(IV) compounds synthesised and evaluated for anticancer activity, bis(4,7-dimethyl-1,10-phenanthroline) sulfatooxovanadium(IV) (metvan) was identified as the most promising multitargeted anticancer vanadium complex with apoptosis-inducing activity. At nanomolar and low micromolar concentrations, metvan induces apoptosis in human leukaemia cells, multiple myeloma cells and solid tumour cells derived from breast cancer, glioblastoma, ovarian, prostate and testicular cancer patients. It is highly effective against cisplatin-resistant ovarian cancer and testicular cancer cell lines. Metvan is much more effective than the standard chemotherapeutic agents dexamethasone and vincristine in inducing apoptosis in primary leukaemia cells from patients with acute lymphoblastic leukaemia, acute myeloid leukaemia or chronic acute myeloid leukaemia. Metvan-induced apoptosis is associated with a loss of mitochondrial transmembrane potential, the generation of reactive oxygen species and depletion of glutathione. Treatment of leukaemia cells from acute lymphoblastic leukaemia, acute myeloid leukaemia and chronic acute myeloid leukaemia patients with metvan inhibits the constitutive expression as well as the gelatinolytic activities of matrix metalloproteinase-9 and -2. Treatment of human malignant glioblastoma and breast cancer cells with metvan at concentrations > 1 microM is associated with a nearly complete loss of the adhesive, migratory and invasive properties of the treated cancer cell populations. Metvan shows favourable pharmacokinetics in mice and does not cause acute or subacute toxicity at the dose levels tested (12.5 - 50 mg/kg). Therapeutic plasma concentrations > or = 5 microM, which are highly cytotoxic against human cancer cells, can be rapidly achieved and maintained in mice for at least 24 h after intraperitoneal bolus injection of a single 10 mg/kg non-toxic dose of metvan. Metvan exhibits significant antitumour activity, delays tumour progression and prolongs survival time in severe combined immunodeficient mouse xenograft models of human malignant glioblastoma and breast cancer. The broad spectrum anticancer activity of metvan together with favourable pharmacodynamic features and lack of toxicity warrants further development of this oxovanadium compound as a new anticancer agent. Metvan could represent the first vanadium complex as an alternative to platinum-based chemotherapy.

Contraceptive activity of a spermicidal aryl phosphate derivative of bromo-methoxy-zidovudine (compound WHI-07) in rabbits.

OBJECTIVE: To determine the vaginal contraceptive activity of WHI-07 in the rabbit model. DESIGN: Prospective, controlled study. SETTING: Center for advanced preclinical sciences. ANIMAL(S): Subgroups of 15, 16, or 24 New Zealand White does and 24 bucks per experiment. INTERVENTION(S): Ex vivo (Experiment 1) and in vivo (Experiments 2 and 3) treatment of semen with WHI-07 or Nonoxynol-9 (N-9). In Experiment I, ovulated does in subgroups of 15 were artificially inseminated with semen mixed with WHI-07 or vehicle. In Experiment 2, ovulated does in subgroups of 24 were artificially inseminated within 2 min after intravaginal administration of 2% WHI-07 gel-microemulsion or 2% N-9 gel and allowed to complete term pregnancy. In Experiment 3, ovulated does in subgroups of 16 were artificially inseminated at 15, 30, or 60 minutes. MAIN OUTCOME MEASURE(S): The numbers of implanted embryos on postinsemination day 8 or the proportion of does that became pregnant and delivered newborn rabbits; the litter size, weight, growth, and viability of pups until lactation day 5. RESULT(S): Exposure of semen to WHI-07 at the time of artificial insemination completely inhibited pregnancy rates (WHI-07-pretreated, 0%, vs. control, 60%) and embryo implantation (WHI-07-pretreated, 0/175 vs. control, 68/170). Intravaginal administration of a 2% WHI-07 gel-microemulsion or 2% N-9 gel before artificial insemination significantly inhibited pregnancy rates (81% and 85% inhibition, respectively) when compared with control. Furthermore, the 2% WHI-07 gel-microemulsion provided >90% inhibition of fertility even when insemination was delayed until 60 minutes after intravaginal application. Rabbits that delivered litters despite intravaginal application of 2% WHI-07 gel-microemulsion had healthy offsprings with no perinatal or postnatal repercussions. CONCLUSION(S): WHI-07 is a potent contraceptive agent in vivo. Intravaginal use of WHI-07 gel-microemulsion has clinical potential as a safe prophylactic contraceptive, in addition to its microbicide activity to curb the sexual transmission of HIV.

Stampidine is a potential nonspermicidal broad-spectrum anti-human immunodeficiency virus microbicide.

OBJECTIVE: Stampidine (2,'3'-didehydro-3'-deoxythymidine-5'-(p-bromophenyl methoxy alaninyl phosphate) is a novel aryl phosphate derivative of stavudine/d4T with broad-spectrum anti-HIV activity in vitro and in vivo. This study investigated the potential utility of stampidine as a nonspermicidal microbicide. DESIGN: Prospective, controlled study. SETTING: Center for Advanced Preclinical Sciences and Reproductive Biology Department. PATIENT(S): Seven sperm donors. ANIMAL(S): Fifty-two sexually mature, female and twenty-four male New Zealand white rabbits. INTERVENTION(S): Human semen and genital tract epithelial cells were exposed to stampidine (up to 1 mM). Ovulated does in subgroups of 12 were artificially inseminated with rabbit semen pretreated with stampidine (1 mM) or vehicle. Does in subgroups of four and three, respectively, were exposed intravaginally to a gel or a thermoreversible ovule formulation with and without 0.5%, 1.0%, or 2.0% stampidine (9 to 36 mM) for 14 days. MAIN OUTCOME MEASURE(S): Effect of stampidine on human sperm motility, kinematics, penetration through cervical mucus, and epithelial cell viability. Reproductive parameters on gestation day 8. Vaginal tissues were histologically scored 24 hours after dosing. RESULT(S): Exposure of human sperm to stampidine even at a concentration 10(6)-times higher than its in vitro anti-HIV-1 activity (50% inhibitory concentration = 1 nM) had no adverse effect on sperm motility, kinematics, cervical mucus penetrability, or the viability of vaginal and endocervical epithelial cells. Reproductive indices of pregnancy rate, embryo implantation, and preimplantation losses were not affected by pretreatment of rabbit semen with stampidine. Gel formulations of 0.5% to 2.0% stampidine (9 to 36 mM) lacked mucosal toxicity. CONCLUSION(S): The broad-spectrum anti-HIV agent stampidine had no adverse effect on sperm functions, was not cytotoxic, and did not induce mucosal toxicity. Stampidine has clinical potential as a prophylactic microbicide without contraceptive activity.

Subchronic (13-week) toxicity studies of intravaginal administration of spermicidal vanadocene acetylacetonato monotriflate in mice.

Bis-cyclopentadienyl complexes of vanadium(IV) or vanadocenes are rapid and potent inhibitors of human sperm motility with potential as a new class of contraceptive agents. In this study, groups of 10 B(6)C(3)F(1) and 20 CD-1 female mice were exposed intravaginally to a gel-microemulsion containing 0, 0.06, 0.12, or 0.25% of a representative vanadocene, vanadocene acetylacetonato monotriflate (VDACAC), five days per week for 13 consecutive weeks. The doses of VDACAC used were nearly 300- to 1250-fold higher than its in vitro spermicidal EC(50) value. After 13 weeks of intravaginal treatment, B(6)C(3)F(1) mice were evaluated for survival, body weight gain, absolute and relative organ weights, and systemic toxicity. Blood was analyzed for hematological and clinical chemistry profiles. Microscopic examination was performed on hematoxylin- and eosin-stained tissue sections from each study animal. Vanadium content in tissues was determined by atomic absorption spectroscopy. Gel-microemulsion (placebo) control and VDACAC dosed female CD-1 mice were mated with untreated males in order to evaluate if VDACAC has any adverse effects on the reproductive outcome. There were no treatment-related mortalities in either study. Mean body weight gain during the dosing period was not reduced by VDACAC treatment. Hemograms or clinical chemistry profiles did not reveal any toxicologically significant changes attributed to VDACAC treatment. No clinically significant dose-dependent changes in absolute and relative organ weights were noted in VDACAC dose groups. Extensive histopathological examination of tissues revealed no treatment-related abnormalities in any of the three VDACAC dose groups. Vanadium was not incorporated in mouse tissues at levels above 1 microg/g. Repeated intravaginal exposure of CD-1 mice to increasing concentrations of VDACAC for 13 weeks had no adverse effect on their subsequent reproductive capability (100% fertile), neonatal survival (>96%) or pup development. Collectively, these findings demonstrate that repetitive intravaginal administration of VDACAC to yield effective spermicidal concentrations (<0.1%) in the vagina was not associated with systemic toxicity and did not adversely affect the reproductive performance in mice. The spermicidal vanadocene-chelated complex, VDACAC, may be useful as a safe vaginal contraceptive.