Polyamine-based polymer electrolyte modification and performance.

Finally, lithium secondary batteries that function at room temperature were built using LPAG2EI based SPE and recycled at different temperatures and drain rates for preliminary evaluation. Although the recycling results were not consistently reproducible, we were able to obtain specific capacities about 90 mAh/g at 100 ° C with the charge/discharge current densities at 10/20 muA/cm2. With the increase of cycle number, the recycling efficiency gradually approached 100%.Linear poly(N-allylethylenimine-co-N-(2-(2-methoxyethoxy)ethylenimine) (LPAG2EI), in which the ratio between the allylic side-chain and G2 side-chain is roughly 1:1, was synthesized. Neutral SPEs with various amounts of LiTf were prepared using the optimum V-50 composition. IR indicates that Tf appears to exist mainly as 'free' ion while DSC shows a relatively low Tg (-15 ° C) and no crystalline phase even at a high salt composition (5:1, N:Li +). Cross-linked LPAG2EI/LiTf SPEs have good physical properties and outstanding ionic conductivity, above 10-5 S/cm at 35 ° C.A viable method for forming neutrally cross-linked solid polymer electrolytes (SPE) by synthetically combining both conductivity enhancing functionality and crosslink-enabling functionality on a polyamine backbone was established. In order to find an appropriate crosslinking functionality, inexpensive branched poly(N-allylethylenimine) (BPAEI) was synthesized from commercially available branched PEI. BPAEI was cross-linked using 2,2-azobis(2-amidinopropane) dihydrochloride (V-50) as radical initiator in the presence of LiTf to form a rubber-like SPE. Although IR shows most Tf ions stay as 'free' ions, the overall conductivity is poor due to a loss of polymer flexibility upon crosslinking as indicated by DSC. The highest conductivity achieved in this system is about 10 -5 S/cm at 80 ° C. The optimum conditions (20:1 N:Li+ ratio, 60:1 N:initiator) for best conductivity were determined.Relatively unexplored polyamine-based polymer electrolytes are being studied as key components in next generation power sources: high energy density and light weight solid state polymer batteries. Understanding the relationship between backbone modification and the resulting property changes of the polyamine-based polymer electrolytes is the focus of the first part of this dissertation. Linear poly(propyleneimine) (LPPI) was synthesized. LPPI were spectroscopically compared with linear poly(ethyleneimine) (LPEI) as a polymer electrolyte host for lithium trifluoromethanesulfonate (LiTf). Infrared spectroscopy (IR) reveals that the ionic association state of LPPI/LiTf is independent of salt concentration, while that of LPEI/LiTf shifts with salt concentration. Differential Scanning Calorimetry (DSC) shows a decrease of crystalline melting endotherms with increasing LiTf concentration in both systems. However, LPPI/LiTf has a relatively constant Tg with changing LiTf concentration, while that of LPEI/LiTf is LiTf concentration dependent. These observations show that both LPPI and LPEI are disrupted into crystalline and amorphous phases upon the addition of salt. However, the amorphous phase of LPPI/LiTf has a relatively constant composition while that of LPEI/LiTf is constantly changing. Consistent with these observations, LPPI/LiTf and LPEI/LiTf have different temperature-dependent ionic conductivity behaviors although they are of similar magnitude, up to 10-7 S/cm at room temperature and 10-3.5 S/cm at 70 ° C. Linear poly(N-methylpropylenimine) (LPMPI) was synthesized from LPPI and was compared to linear poly(N-methylethylenimine) (LPMEI). Research on LPMPI polymer electrolytes is ongoing

Efficacy of Carraguard®-Based Microbicides In Vivo Despite Variable In Vitro Activity

Anti-HIV microbicides are being investigated in clinical trials and understanding how promising strategies work, coincident with demonstrating efficacy in vivo, is central to advancing new generation microbicides. We evaluated Carraguard® and a new generation Carraguard-based formulation containing the non-nucleoside reverse transcriptase inhibitor (NNRTI) MIV-150 (PC-817). Since dendritic cells (DCs) are believed to be important in HIV transmission, the formulations were tested for the ability to limit DC-driven infection in vitro versus vaginal infection of macaques with RT-SHIV (SIVmac239 bearing HIV reverse transcriptase). Carraguard showed limited activity against cell-free and mature DC-driven RT-SHIV infections and, surprisingly, low doses of Carraguard enhanced infection. However, nanomolar amounts of MIV-150 overcame enhancement and blocked DC-transmitted infection. In contrast, Carraguard impeded infection of immature DCs coincident with DC maturation. Despite this variable activity in vitro, Carraguard and PC-817 prevented vaginal transmission of RT-SHIV when applied 30 min prior to challenge. PC-817 appeared no more effective than Carraguard in vivo, due to the limited activity of a single dose of MIV-150 and the dominant barrier effect of Carraguard. However, 3 doses of MIV-150 in placebo gel at and around challenge limited vaginal infection, demonstrating the potential activity of a topically applied NNRTI. These data demonstrate discordant observations when comparing in vitro and in vivo efficacy of Carraguard-based microbicides, highlighting the difficulties in testing putative anti-viral strategies in vitro to predict in vivo activity. This work also underscores the potential of Carraguard-based formulations for the delivery of anti-viral drugs to prevent vaginal HIV infection

A Macaque Model to Study Vaginal HSV-2/Immunodeficiency Virus Co-Infection and the Impact of HSV-2 on Microbicide Efficacy

Herpes simplex virus type-2 (HSV-2) infection enhances the transmission and acquisition of human immunodeficiency virus (HIV). This occurs in symptomatic and asymptomatic stages of HSV-2 infection, suggesting that obvious herpetic lesions are not required to increase HIV spread. An animal model to investigate the underlying causes of the synergistic action of the two viruses and where preventative strategies can be tested under such complex physiological conditions is currently unavailable.We set out to establish a rhesus macaque model in which HSV-2 infection increases the susceptibility to vaginal infection with a model immunodeficiency virus (simian-human immunodeficiency virus, SHIV-RT), and to more stringently test promising microbicides. HSV-2 exposure significantly increased the frequency of vaginal SHIV-RT infection (n = 6). Although cervical lesions were detected in only approximately 10% of the animals, long term HSV-2 DNA shedding was detected (in 50% of animals followed for 2 years). Vaginal HSV-2 exposure elicited local cytokine/chemokine (n = 12) and systemic low-level HSV-2-specific adaptive responses in all animals (n = 8), involving CD4(+) and CD8(+) HSV-specific T cells (n = 5). Local cytokine/chemokine responses were lower in co-infected animals, while simian immunodeficiency virus (SIV)-specific adaptive responses were comparable in naïve and HSV-2-infected animals (n = 6). Despite the increased frequency of SHIV-RT infection, a new generation microbicide gel, comprised of Carraguard(R) and a non-nucleoside reverse transcriptase inhibitor MIV-150 (PC-817), blocked vaginal SHIV-RT infection in HSV-2-exposed animals (n = 8), just as in naïve animals.We established a unique HSV-2 macaque model that will likely facilitate research to define how HSV-2 increases HIV transmission, and enable more rigorous evaluation of candidate anti-viral approaches in vivo

Carraguard can inhibit or enhance cell-free infection.

<p>(A) TZM.bl cells were exposed to 0–10 µg/ml of Carraguard, before graded doses of HIV_Bal or RT-SHIV were added. 24 h later, the media was replaced and cells were cultured for 4 d. The numbers of β-gal expressing SFCs per well are shown (mean±SD, triplicate cultures). (B) Titrated amounts of Carraguard were tested against of HIV_MN (MN, up triangles), HIV_Bal (Bal) (down triangles), or RT-SHIV (circles) in the TZM.bl cell line as in (A). The data are shown as the percent inhibition (mean±SD, triplicate cultures) of infection in the test conditions relative to the no Carraguard control. Negative % inhibition values represent enhancement, with no inhibitor effect at 0%. (C) Titrated amounts of Carraguard were added to PHA activated PBMCs before the cells were cultured with Bal or RT-SHIV for 5 d. Infection was measured by Q-PCR. Data are shown for triplicate cultures (mean±SD). Data in (A–C) are representative of 3 independent experiments with different donors in each case.</p

<i>In vivo</i> activity of MIV-150-containing MC gels.

<p>Depo-Provera-treated animals were treated with (A) 3 ml of MC containing 500 µM MIV-150 30 min prior to vaginal challenge with 10³ or 10⁴ TCID₅₀ of RT-SHIV or (B) 3 ml of MC containing 500 µM MIV-150 24 h before, 30 min before, and 24 h after vaginal challenge with 10⁴ TCID₅₀ of RT-SHIV. Plasma viral loads over time are shown for the indicated numbers of animals in each group. One year after challenge the 3 animals with the low-level initial infection (now with undetectable virus) and two of the normally infected animals were treated with the anti-CD8 mAb to deplete CD8 cells. (C) Effective depletion of CD8 cells was verified by flow cytometry and the CD8 cells per µl of blood are shown for each animal. (D) Analysis of the plasma virus loads before during and after CD8 depletion, revealed no rebound in virus levels in the 3 animals with the unusual acute low-level infection. Each symbol denotes a different animal that are detailed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0003162#pone-0003162-t001" target="_blank">Table 1</a>.</p

Carraguard inhibits infection in immature DCs coincident with DC maturation.

<p>(A) Immature DCs were pre-incubated with graded doses of Carraguard, after which the DCs were challenged with Bal (down triangles) or HIV Δenv pseudotyped with the VSVg envelope (Δenv, filled squares). Cells were harvested 5 d later and stained for (A) HIV capsid p24 protein (mAb KC-57-RD1) or (B) the surface maturation markers CD83 and CD86. (A) Percent inhibition (mean±SD, triplicates) of infection and (B) the MFIs (mean±SD of triplicates) of CD83 (black bar) and CD86 (grey bar) expression (on the entire DC population) are shown for 1 of 4 replicate experiments. CD83 and CD86 up-regulation in response to increasing doses of Carraguard correlate closely (r = 0.99). (C) p24 expression is plotted against CD83, showing the correlation between lower CD83 levels and HIV infection. Comparable results were obtained when comparing CD86 and p24 expression (data not shown).</p

Carraguard-based gels inhibit vaginal infection in macaques.

<p>Depo-Provera-treated animals were treated with 3 ml of MC, Carraguard (Carr), or PC-817 30 min prior to challenge with 1 ml of or 10³–10⁵ TCID₅₀ RT-SHIV. (A) Plasma viral loads were quantified by PCR and SIV gag RNA copies per ml of plasma are shown for each animal over time. The numbers of animals in the respective groups are indicated in each panel. Each symbol denotes a different animal (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0003162#pone-0003162-t001" target="_blank">Table 1</a>). (B) The frequencies (percentage of infected animals, mean±SEM) of infection in the MC, Carraguard, and PC-817-treated groups challenged with 10³ and 10⁴ TCID₅₀ are plotted. Carraguard (p<0.02) and PC-817 (p<0.03) significantly reduced the frequency of immunodeficiency virus infection compared to the MC-treated placebo group.</p

Infection and immune status of RT-SHIV-challenged macaques.

ˆ<p>CD4 counts taken on day 84 for DE38, day 189 for FI76, FI78, FI70, FI71, FI73, and FI75, and day 196 for FI86 and FI87.</p>$<p>Co-cultures of PBMCs with 174×CEM cells were scored as positive by microscopic examination of syncytia formation and in some instances verified by PCR for SIV gag.</p>&<p>DE38 had two timepoints of positive IFNγ responses at weeks 8 and 10 post challenge.</p>*<p>GF14 - average 715 copies/ml on day 42 post challenge, but the animal remained below the level of detection at all other time points.</p>%<p>500 µM of MIV-150 in MC administered once 30 min prior to challenge (1X) or 24 h before, 30 min before, and 30 min after virus challenge (3X).</p>@<p>These animals exhibited low-level viremia but ultimately controlled infection to undetectable levels even after CD8 depletion.</p><p>Ab positivity was defined as having at least two positive OD values above baseline at 4 weeks post challenge and IFNγ positivity was defined as having at least 50 SIV-specific IFNγ SFCs per 10⁶ PBMCs on more than one time point post challenge.</p><p>ND, not determined.</p

Carraguard augments mature DC-mediated amplification of infection.

<p>(A) Mature moDCs were pre-incubated with 0, 10, or 200 µg/ml Carraguard and challenged with graded doses of Bal or RT-SHIV, washed, and co-cultured with TZM.bl cells. Mean SFCs (±SD, triplicate conditions) are shown from 1 of 4 experiments. (B) Carraguard-treated mature DCs were pulsed with Bal or RT-SHIV, washed, and co-cultured with TZM.bl cells as in (A). The percent inhibition of infection (mean±SD, triplicate conditions) is shown for 1 of 4 experiments. A statistically significant difference (p<0.05, two-tailed paired <i>t</i>-test) between the enhancement effects on Bal vs RT-SHIV infection is noted by the asterisk. (C) Mature DCs pre-treated with Carraguard (Pre, open squares) were challenged with 3000 TCID₅₀ of Bal or 4500 TCID₅₀ of RT-SHIV, washed, and co-cultured with TZM.bl cells. Alternatively, mature DCs were pulsed with virus, washed, added to TZM.bl cells and the graded doses of Carraguard added to the co-cultures (Post, filled squares). The percent inhibition (mean±SD, triplicates) are shown from 1 of 4 experiments. A statistically significant difference (p<0.01, two-tailed paired <i>t</i>-test) between the pre versus post Carraguard enhancement effects on Bal infection is noted by the asterisk.</p