Virus-Like Particle-Drug Conjugates Induce Protective, Long-lasting Adaptive Antitumor Immunity in the Absence of Specifically Targeted Tumor Antigens

This study examined the ability of a papillomavirus-like particle drug conjugate, belzupacap sarotalocan (AU-011), to eradicate subcutaneous tumors after intravenous injection and to subsequently elicit long-term antitumor immunity in the TC-1 syngeneic murine tumor model. Upon in vitro activation with near-infrared light (NIR), AU-011-mediated cell killing was proimmunogenic in nature, resulting in the release of damage-associated molecular patterns such as DNA, ATP, and HMGB-1, activation of caspase-1, and surface relocalization of calreticulin and HSP70 on killed tumor cells. A single in vivo administration of AU-011 followed by NIR caused rapid cell death, leading to long-term tumor regression in ∼50% of all animals. Within hours of treatment, calreticulin surface expression, caspase-1 activation, and depletion of immunosuppressive leukocytes were observed in tumors. Combination of AU-011 with immune-checkpoint inhibitor antibodies, anti-CTLA-4 or anti-PD-1, improved therapeutic efficacy, resulting in 70% to 100% complete response rate that was durable 100 days after treatment, with 50% to 80% of those animals displaying protection from secondary tumor rechallenge. Depletion of CD4⁺ or CD8⁺ T cells, either at the time of AU-011 treatment or secondary tumor rechallenge of tumor-free mice, indicated that both cell populations are vital to AU-011's ability to eradicate primary tumors and induce long-lasting antitumor protection. Tumor-specific CD8⁺ T-cell responses could be observed in circulating peripheral blood mononuclear cells within 3 weeks of AU-011 treatment. These data, taken together, support the conclusion that AU-011 has a direct cytotoxic effect on tumor cells and induces long-term antitumor immunity, and this activity is enhanced when combined with checkpoint inhibitor antibodies.

Abstract 5563: Harnessing pre-existing viral immunity for development of a broadly applicable tumor immunotherapy

The availability of high throughput DNA sequencing provides an opportunity to generate a potent immune stimulation against unique antigens expressed by tumors. Although such approaches have led to increased immune responses in certain individuals, it is often limited to a small patient population and is associated with high development and implementation costs. Therefore, there is an unmet need for an immunotherapy that is easy to manufacture at affordable cost and applicable across many different tumor types. Here, we propose a unique approach to leverage pre-existing anti-Human Cytomegalovirus (CMV) immunity using a defined cocktail of viral epitopes, to both directly kill the tumor cells and induce a secondary T cell response to tumor neoantigens. We chose to recruit CMV immunity because CMV infection is highly prevalent, reaching approximately 90% of the population by the age of 80 years, and because of the naturally-occurring inflation of anti-CMV T cell responses with age leads to high levels CMV-specific T cells. Consequently, in elderly individuals, CMV-specific T cells recognizing a limited number of viral epitopes constitute approximately 10% of all systemic CD4 and CD8 T cells, a level rarely achieved by conventional vaccination. Additionally, in contrast to other chronic viral infections, CMV-specific T cells remain highly functional. In our experimental model, mice persistently infected with Murine Cytomegalovirus (mCMV) were subcutaneously challenged with TC-1 tumor cells (expressing human papillomavirus E6 and E7 oncogenes) or colon adenocarcinoma MC38 tumor cells, followed by intratumoral injections of mCMV peptide antigens together with a Toll-like receptor 3 (TLR3) agonist poly(I:C). Intratumoral injection of mCMV MHC-I or MHC-II restricted epitopes alone led to local and systemic recall of mCMV-specific T cells, and a potent local immune activation resulting in complete rejection of TC-1 and MC38 tumors in a subset of animals. Coinjection of both MHC-I and MHC-II peptides resulted in complete tumor clearance is most animals. Clearance was associated with antigen spreading, as evidenced by protection from secondary tumor challenge and ex vivo IFN-gamma ELISPOT responses to tumor-specific epitopes. Our preclinical studies provide a proof of concept of a first-in-class tumor antigen-agnostic immunotherapy based on recruitment of pre-existing antiviral T cells. The approach induced rapid tumor regression, profound changes in the tumor immune environment, epitope spreading, and resulted in long-term tumor protection. We are currently investigating the contribution of other cell types including NK cells and B cells to the anti-tumor effect of our approach.

Citation Format: Nicolas Cuburu, Lukas Bialkowski, Sergio M. Pontejo, Alexander Bell, Rina Kim, Cynthia D. Thompson, Douglas R. Lowy, John T. Schiller. Harnessing pre-existing viral immunity for development of a broadly applicable tumor immunotherapy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5563.

A Prime-Pull-Amplify Vaccination Strategy To Maximize Induction of Circulating and Genital-Resident Intraepithelial CD8+ Memory T Cells

Recent insight into the mechanisms of induction of tissue-resident memory (T_RM) CD8⁺ T cells (CD8⁺ T_RM) enables the development of novel vaccine strategies against sexually transmitted infections. To maximize both systemic and genital intraepithelial CD8⁺ T cells against vaccine Ags, we assessed combinations of i.m. and intravaginal routes in heterologous prime-boost immunization regimens with unrelated viral vectors. Only i.m. prime followed by intravaginal boost induced concomitant strong systemic and intraepithelial genital-resident CD8⁺ T cell responses. Intravaginal boost with vectors expressing vaccine Ags was far superior to intravaginal instillation of CXCR3 chemokine receptor ligands or TLR 3, 7, and 9 agonists to recruit and increase the pool of cervicovaginal CD8⁺ T_RM Transient Ag presentation increased trafficking of cognate and bystander circulating activated, but not naive, CD8⁺ T cells into the genital tract and induced in situ proliferation and differentiation of cognate CD8⁺ T_RM Secondary genital CD8⁺ T_RM were induced in the absence of CD4⁺ T cell help and shared a similar TCR repertoire with systemic CD8⁺ T cells. This prime-pull-amplify approach elicited systemic and genital CD8⁺ T cell responses against high-risk human papillomavirus type 16 E7 oncoprotein and conferred CD8-mediated protection to a vaccinia virus genital challenge. These results underscore the importance of the delivery route of nonreplicating vectors in prime-boost immunization to shape the tissue distribution of CD8⁺ T cell responses. In this context, the importance of local Ag presentation to elicit genital CD8⁺ T_RM provides a rationale to develop novel vaccines against sexually transmitted infections and to treat human papillomavirus neoplasia.

Adenovirus vector-based prime-boost vaccination via heterologous routes induces cervicovaginal CD8+ T cell responses against HPV16 oncoproteins

Recent advances in immunotherapy against cancer underscore the importance of T lymphocytes and tumor microenvironment, but few vaccines targeting cancer have been approved likely due in part to the dearth of common tumor antigens, insufficient immunogenicity and the evolution of immune evasion mechanisms during the progression to malignancy. Human papillomaviruses (HPVs) are the primary etiologic agents of cervical cancer and progression from persistent HPV-infection to cervical intraepithelial lesions and eventually cancer requires persistent expression of the oncoproteins E6 and E7. This offers the opportunity to specifically target these virus-specific antigens for vaccine-induced clearance of infected cells before cancers develop. Here we have evaluated the immunogenicity of Adenovirus Types 26 and 35 derived vectors expressing a fusion of HPV16 E6 and E7 oncoproteins after intramuscular (IM) and/or intravaginal (Ivag) immunization in mice. The adenovirus vectors were shown to transduce an intact cervicovaginal epithelium. IM prime followed by Ivag boost maximized the induction and trafficking of HPV-specific CD8⁺ T cells producing IFN-γ and TNF-α to the cervicovaginal tract. Importantly, the cervicovaginal CD8⁺ T cells expressed CD69 and CD103; hallmarks of intraepithelial tissue-resident memory CD8⁺ T cells. This prime-boost strategy targeting heterologous locations also induced circulating HPV-specific CD8⁺ T cell responses. Our study prompts further evaluation of Ivag immunization with adenoviral vectors expressing modified E6 and E7 antigens for therapeutic vaccination against persistent HPV infection and cervical intraepithelial neoplasia.

Efficient Production of Papillomavirus Gene Delivery Vectors in Defined In Vitro Reactions

Papillomavirus capsids can package a wide variety of nonviral DNA plasmids and deliver the packaged genetic material to cells, making them attractive candidates for targeted gene delivery vehicles. However, the papillomavirus vectors generated by current methods are unlikely to be suitable for clinical applications. We have developed a chemically defined, cell-free, papillomavirus-based vector production system that allows the incorporation of purified plasmid DNA (pseudogenome) into high-titer papillomavirus L1/L2 capsids. We investigated the incorporation of several DNA forms into a variety of different papillomavirus types, including human and animal types. Our results show that papillomavirus capsids can package and transduce linear or circular DNA under defined conditions. Packaging and transduction efficiencies were surprisingly variable across capsid types, DNA forms, and assembly reaction conditions. The pseudoviruses produced by these methods are sensitive to the same entry inhibitors as cell-derived pseudovirions, including neutralizing antibodies and heparin. The papillomavirus vector production systems developed in this study generated as high as 10¹¹ infectious units/mg of L1. The pseudoviruses were infectious both in vitro and in vivo and should be compatible with good manufacturing practice (GMP) requirements.

Human papillomavirus capsids preferentially bind and infect tumor cells

We previously determined that human papillomavirus (HPV) virus-like particles (VLPs) and pseudovirions (PsV) did not, respectively, bind to or infect intact epithelium of the cervicovaginal tract. However, they strongly bound heparan sulfate proteoglycans (HSPG) on the basement membrane of disrupted epithelium and infected the keratinocytes that subsequently entered the disrupted site. We here report that HPV capsids (VLP and PsV) have the same restricted tropism for a wide variety of disrupted epithelial and mesothelial tissues, whereas intact tissues remain resistant to binding. However, the HPV capsids directly bind and infect most tumor-derived cell lines in vitro and have analogous tumor-specific properties in vivo, after local or intravenous injection, using orthotopic models for human ovarian and lung cancer, respectively. The pseudovirions also specifically infected implanted primary human ovarian tumors. Heparin and ι-carrageenan blocked binding and infection of all tumor lines tested, implying that tumor cell binding is HSPG-dependent. A survey using a panel of modified heparins indicates that N-sulfation and, to a lesser degree, O-6 sulfation of the surface HSPG on the tumors are important for HPV binding. Therefore, it appears that tumor cells consistently evolve HSPG modification patterns that mimic the pattern normally found on the basement membrane but not on the apical surfaces of normal epithelial or mesothelial cells. Consequently, appropriately modified HPV VLPs and/or PsV could be useful reagents to detect and potentially treat a remarkably broad spectrum of cancers.

Involvement of Nucleophosmin (NPM1/B23) in Assembly of Infectious HPV16 Capsids

We report that during assembly of HPV16 pseudovirus (PsV) the minor capsid protein, L2, interacts with the host nucleolar protein nucleophosmin (NPM1/B23). Exogenously-expressed L2 colocalized with NPM1, a complex containing both proteins could be immunoprecipitated, and L2 could redirect to the nucleus NPM1 that was pharmacologically or genetically restricted to the cytoplasm. Coexpression of the major capsid protein, L1, prevented both the colocalization and the biochemical association, and L1 pentamers could displace L2 from L2/NPM1 complexes attached to a nuclear matrix. HPV16 PsV that was produced in a cell line with reduced NPM1 levels had significantly lower infectivity compared to PsV produced in the parental cell line, although the PsV preparations had comparable L1 and L2 ratios and levels of encapsidated DNA. The PsV produced in NPM1-deficient cells showed increased trypsin sensitivity and exhibited decreased L2 levels during endocytosis. These results suggest a critical role for NPM1 in establishing the correct interactions between L2 and L1 during HPV capsid assembly. A decrease in cellular levels of NPM1 results in the formation of seemingly normal, but unstable, capsids that result in a premature loss of L2, thus inhibiting successful infection. No role for NPM1 in HPV infectious entry was found.

Mouse model of cervicovaginal papillomavirus infection

Virtually all cervical cancers are caused by human papillomavirus infections. The efficient assembly of pseudovirus (PsV) particles incorporating a plasmid expressing a reporter gene has been an invaluable tool in the development of in vitro neutralization assays and in studies of the early mechanisms of viral entry in vitro. Here, we describe a mouse model of human papillomavirus PsV infection of the cervicovaginal epithelium that recapitulates the early events of papillomavirus infection in vivo.

Strain-specific properties and T cells regulate the susceptibility to papilloma induction by Mus musculus papillomavirus 1

The immunocytes that regulate papillomavirus infection and lesion development in humans and animals remain largely undefined. We found that immunocompetent mice with varying H-2 haplotypes displayed asymptomatic skin infection that produced L1 when challenged with 6×1010 MusPV1 virions, the recently identified domestic mouse papillomavirus (also designated "MmuPV1"), but were uniformly resistant to MusPV1-induced papillomatosis. Broad immunosuppression with cyclosporin A resulted in variable induction of papillomas after experimental infection with a similar dose, from robust in Cr:ORL SENCAR to none in C57BL/6 mice, with lesional outgrowth correlating with early viral gene expression and partly with reported strain-specific susceptibility to chemical carcinogens, but not with H-2 haplotype. Challenge with 1×1012 virions in the absence of immunosuppression induced small transient papillomas in Cr:ORL SENCAR but not in C57BL/6 mice. Antibody-induced depletion of CD3+ T cells permitted efficient virus replication and papilloma formation in both strains, providing experimental proof for the crucial role of T cells in controlling papillomavirus infection and associated disease. In Cr:ORL SENCAR mice, immunodepletion of either CD4+ or CD8+ T cells was sufficient for efficient infection and papillomatosis, although deletion of one subset did not inhibit the recruitment of the other subset to the infected epithelium. Thus, the functional cooperation of CD4+ and CD8+ T cells is required to protect this strain. In contrast, C57BL/6 mice required depletion of both CD4+ and CD8+ T cells for infection and papillomatosis, and separate CD4 knock-out and CD8 knock-out C57BL/6 were also resistant. Thus, in C57BL/6 mice, either CD4+ or CD8+ T cell-independent mechanisms exist that can protect this particular strain from MusPV1-associated disease. These findings may help to explain the diversity of pathological outcomes in immunocompetent humans after infection with a specific human papillomavirus genotype.

Murine skin and vaginal mucosa are similarly susceptible to infection by pseudovirions of different papillomavirus classifications and species

Depending upon viral genotype, productive papillomavirus infection and disease display preferential tropism for cutaneous or mucosal stratified squamous epithelia, although the mechanisms are unclear. To investigate papillomavirus entry tropism, we used reporter pseudovirions based on various cutaneous and mucosal papillomavirus species, including the recently identified murine papillomavirus. Pseudovirus transduction of BALB/c mice was examined using an improved murine skin infection protocol and a previously developed cervicovaginal challenge model. In the skin, HPV5, HPV6, HPV16, BPV1 and MusPV1 pseudovirions preferentially transduced keratinocytes at sites of trauma, similar to the genital tract. Skin infection, visualized by in vivo imaging using a luciferase reporter gene, peaked between days 2-3 and rapidly diminished for all pseudovirion types. Murine cutaneous and genital tissues were similarily permissive for pseudovirions of HPV types 5, 6, 8, 16, 18, 26, 44, 45, 51, 58 and animal papillomaviruses BPV1 and MusPV1, implying that papillomavirus' tissue and host tropism is governed primarily by post-entry regulatory events in the mouse.

UGT2B17 genetic polymorphisms dramatically affect the pharmacokinetics of MK-7246 in healthy subjects in a first-in-human study

MK-7246, an antagonist of the chemoattractant receptor on T helper type 2 (Th2) cells, is being developed for the treatment of respiratory diseases. In a first-in-human study, we investigated whether genetic polymorphisms contributed to the marked intersubject variability in the pharmacokinetics of MK-7246 and its glucuronide metabolite M3. Results from in vitro enzyme kinetic studies suggested that UGT2B17 is probably the major enzyme responsible for MK-7246 metabolism in both the liver and the intestine. As compared with those with the UGT2B17*1/*1 wild-type genotype, UGT2B17*2/*2 carriers, who possess no UGT2B17 protein, had 25- and 82-fold greater mean dose-normalized values of area under the plasma concentration–time curve (AUC) and peak concentration of MK-7246, respectively, and a 24-fold lower M3-to-MK-7246 AUC ratio. The apparent half-life of MK-7246 was not as variable between these two genotypes. Therefore, the highly variable pharmacokinetics of MK-7246 is attributable primarily to the impact of UGT2B17 genetic polymorphisms and extensive first-pass metabolism of MK-7246.

Production of papillomavirus-based gene transfer vectors

Papillomaviruses are a diverse group of pathogens that infect the skin and mucosal tissues of humans and various animal species. The viral genome is a circular, double-stranded DNA molecule approximately 8-kb in length. The non-enveloped papillomavirus capsid is composed of a virally encoded major coat protein, L1, and a minor coat protein, L2. L1 and L2 co-assemble when expressed in mammalian cells, and can promiscuously encapsidate essentially any <8-kb plasmid present in the cell nucleus. In the last several years, there has been rapid development of techniques for intracellular production of papillomavirus-based gene transfer vectors (also known as pseudoviruses). This unit outlines the production and propagative amplification of papillomaviral vectors. The system represents a highly tractable method for converting pre-existing mammalian expression plasmids into infectious virus stocks. The resulting vectors have utility for in vitro, as well as in vivo gene delivery applications.

Alterations in attentional mechanisms in response to acute inflammatory pain and morphine administration

Research indicates that pain negatively impacts attention; however, the extent of this impact and the mechanisms of the effect of pain on normal attentional processing remain unclear. This study 1) examined the impact of acute inflammatory pain on attentional processing, 2) examined the impact of morphine on attentional processing, and 3) determined if an analgesic dose of morphine would return attentional processing to normal levels. Male Sprague-Dawley rats were trained on the 5 choice serial reaction time task (5CSRTT), a test commonly used to assess the attentional mechanisms of rodents. Animals were injected with saline or 1, 3, or 6 mg/kg of morphine. Twenty minutes later, animals received a formalin (or saline) injection into one hind paw to induce an inflammatory condition and were then immediately tested in the 5CSRTT. The results show that the formalin injection significantly impaired performance, as measured by an increase in the number of trials in which the animal failed to attend to the task. Likewise, a high dose of morphine (6 mg/kg) produced similar decrements in task performance. Of primary importance is that 3 mg/kg of morphine produced analgesia with only mild sedation, and performance in the 5CSRTT was improved with this dose. This is the first study to use an animal model of acute pain to demonstrate the negative impact of pain on attention, and provides a novel approach to examine the neural correlates that underlie the disruptive impact of pain on attention.

Genital transmission of HPV in a mouse model is potentiated by nonoxynol-9 and inhibited by carrageenan

Genital human papillomavirus (HPV) infection is the most common sexually transmitted infection, and virtually all cases of cervical cancer are attributable to infection by a subset of HPVs (reviewed in ref. 1). Despite the high incidence of HPV infection and the recent development of a prophylactic vaccine that confers protection against some HPV types, many features of HPV infection are poorly understood. It remains worthwhile to consider other interventions against genital HPVs, particularly those that target infections not prevented by the current vaccine. However, productive papillomavirus infection is species- and tissue-restricted, and traditional models use animal papillomaviruses that infect the skin or oral mucosa. Here we report the development of a mouse model of cervicovaginal infection with HPV16 that recapitulates the establishment phase of papillomavirus infection. Transduction of a reporter gene by an HPV16 pseudovirus was characterized by histology and quantified by whole-organ, multispectral imaging. Disruption of the integrity of the stratified or columnar genital epithelium was required for infection, which occurred after deposition of the virus on the basement membrane underlying basal keratinocytes. A widely used vaginal spermicide, nonoxynol-9 (N-9), greatly increased susceptibility to infection. In contrast, carrageenan, a polysaccharide present in some vaginal lubricants, prevented infection even in the presence of N-9, suggesting that carrageenan might serve as an effective topical HPV microbicide.

Neutralization of human papillomavirus with monoclonal antibodies reveals different mechanisms of inhibition

The mechanisms of human papillomavirus (HPV) neutralization by antibodies are incompletely understood. We have used HPV16 pseudovirus infection of HaCaT cells to analyze how several neutralizing monoclonal antibodies (MAbs) generated against HPV16 L1 interfere with the process of keratinocyte infection. HPV16 capsids normally bind to both the cell surface and extracellular matrix (ECM) of HaCaT cells. Surprisingly, two strongly neutralizing MAbs, V5 and E70, did not prevent attachment of capsids to the cell surface. However, they did block association with the ECM and prevented internalization of cell surface-bound capsids. In contrast, MAb U4 prevented binding to the cell surface but not to the ECM. The epitope recognized by U4 was inaccessible when virions were bound to the cell surface but became accessible after endocytosis, presumably coinciding with receptor detachment. Treatment of capsids with heparin, which is known to interfere with binding to cell surface heparan sulfate proteoglycans (HSPGs), also resulted in HPV16 localization to the ECM. These results suggest that the U4 epitope on the intercapsomeric C-terminal arm is likely to encompass the critical HSPG interaction residues for HPV16, while the V5 and E70 epitopes at the apex of the capsomer overlap the ECM-binding sites. We conclude that neutralizing antibodies can inhibit HPV infection by multiple distinct mechanisms, and understanding these mechanisms can add insight to the HPV entry processes.

Infrared spectra of the Li+–(H2)n (n=1–3) cation complexes

The Li+-(H2)n n=1-3 complexes are investigated through infrared spectra recorded in the H-H stretch region (3980-4120 cm-1) and through ab initio calculations at the MP2/aug-cc-pVQZ level. The rotationally resolved H-H stretch band of Li+-H2 is centered at 4053.4 cm-1 [a -108 cm-1 shift from the Q1(0) transition of H2]. The spectrum exhibits rotational substructure consistent with the complex possessing a T-shaped equilibrium geometry, with the Li+ ion attached to a slightly perturbed H2 molecule. Around 100 rovibrational transitions belonging to parallel Ka=0-0, 1-1, 2-2, and 3-3 subbands are observed. The Ka=0-0 and 1-1 transitions are fitted by a Watson A-reduced Hamiltonian yielding effective molecular parameters. The vibrationally averaged intermolecular separation in the ground vibrational state is estimated as 2.056 A increasing by 0.004 A when the H2 subunit is vibrationally excited. The spectroscopic data are compared to results from rovibrational calculations using recent three dimensional Li+-H2 potential energy surfaces [Martinazzo et al., J. Chem. Phys. 119, 11241 (2003); Kraemer and Spirko, Chem. Phys. 330, 190 (2006)]. The H-H stretch band of Li+-(H2)2, which is centered at 4055.5 cm-1 also exhibits resolved rovibrational structure. The spectroscopic data along with ab initio calculations support a H2-Li+-H2 geometry, in which the two H2 molecules are disposed on opposite sides of the central Li+ ion. The two equivalent Li+...H2 bonds have approximately the same length as the intermolecular bond in Li+-H2. The Li+-(H2)3 cluster is predicted to possess a trigonal structure in which a central Li+ ion is surrounded by three equivalent H2 molecules. Its infrared spectrum features a broad unresolved band centered at 4060 cm-1.

Carrageenan is a potent inhibitor of papillomavirus infection

Certain sexually transmitted human papillomavirus (HPV) types are causally associated with the development of cervical cancer. Our recent development of high-titer HPV pseudoviruses has made it possible to perform high-throughput in vitro screens to identify HPV infection inhibitors. Comparison of a variety of compounds revealed that carrageenan, a type of sulfated polysaccharide extracted from red algae, is an extremely potent infection inhibitor for a broad range of sexually transmitted HPVs. Although carrageenan can inhibit herpes simplex viruses and some strains of HIV in vitro, genital HPVs are about a thousand-fold more susceptible, with 50% inhibitory doses in the low ng/ml range. Carrageenan acts primarily by preventing the binding of HPV virions to cells. This finding is consistent with the fact that carrageenan resembles heparan sulfate, an HPV cell-attachment factor. However, carrageenan is three orders of magnitude more potent than heparin, a form of cell-free heparan sulfate that has been regarded as a highly effective model HPV inhibitor. Carrageenan can also block HPV infection through a second, postattachment heparan sulfate–independent effect. Carrageenan is in widespread commercial use as a thickener in a variety of cosmetic and food products, ranging from sexual lubricants to infant feeding formulas. Some of these products block HPV infectivity in vitro, even when diluted a million-fold. Clinical trials are needed to determine whether carrageenan-based products are effective as topical microbicides against genital HPVs.

Sexually transmitted human papillomavirus (HPV) infections are very common. Although most HPV infections don't cause noticeable symptoms, persistent infection with some genital HPV types can lead to cervical cancer or other anal/genital cancers. Another subset of HPV types can cause genital warts. Recent studies have suggested that condoms are not highly effective in preventing HPV infection. Although HPV vaccines will soon become available, they probably will not protect against all genital HPV types and will be too expensive for use in the developing world. Inexpensive HPV-inhibitory compounds (known as topical microbicides) might be useful for blocking the spread of HPV. Using a newly developed cell culture–based HPV inhibition test, we have discovered that an inexpensive gelling agent called carrageenan is an unexpectedly potent HPV infection inhibitor. Carrageenan is also under investigation as a topical microbicide targeting HIV and herpes viruses, but it is a thousand times more effective against HPV in cell culture tests. Interestingly, carrageenan is used as a thickener in some commercially available sexual lubricants and lubricated condoms. Several of these commercial lubricant products are potent HPV inhibitors in our cell culture–infection system. Clinical trials are needed to determine the effectiveness of carrageenan as a topical microbicide against HPV.

Rotationally resolved infrared spectrum of the Li+–D2 cation complex

The infrared spectrum of mass selected Li(+)-D(2) cations is recorded in the D-D stretch region (2860-2950 cm(-1)) in a tandem mass spectrometer by monitoring Li(+) photofragments. The D-D stretch vibration of Li(+)-D(2) is shifted by -79 cm(-1) from that of the free D(2) molecule indicating that the vibrational excitation of the D(2) subunit strengthens the effective Li(+)cdots, three dots, centeredD(2) intermolecular interaction. Around 100 rovibrational transitions, belonging to parallel K(a)=0-0, 1-1, and 2-2 subbands, are fitted to a Watson A-reduced Hamiltonian to yield effective molecular parameters. The infrared spectrum shows that the complex consists of a Li(+) ion attached to a slightly perturbed D(2) molecule with a T-shaped equilibrium configuration and a 2.035 A vibrationally averaged intermolecular separation. Comparisons are made between the spectroscopic data and data obtained from rovibrational calculations using a recent three dimensional Li(+)-D(2) potential energy surface [R. Martinazzo, G. Tantardini, E. Bodo, and F. Gianturco, J. Chem. Phys. 119, 11241 (2003)].

Human alpha-defensins block papillomavirus infection

Sexually transmitted human papillomaviruses (HPVs) are the primary cause of cervical cancer. Recent advances in techniques for production of papillomaviral vectors [known as pseudoviruses (PsVs)] have made it possible to perform high-throughput screens for compounds that might block the initial stages of papillomavirus infection. We have used PsVs to screen a variety of compounds that might function as inhibitors of HPV infection, with emphasis on human peptides previously implicated in innate antimicrobial immunity. Little is known about the possible activity of these peptides against nonenveloped viruses, such as HPVs. Our screen revealed that human alpha-defensins 1-3 [known as human neutrophil peptides (HNPs) 1-3] and human alpha-defensin 5 (HD-5) are potent antagonists of infection by both cutaneous and mucosal papillomavirus types. In contrast, human beta-defensins 1 and 2 displayed little or no anti-HPV activity. HD-5 was particularly active against sexually transmitted HPV types, with 50% inhibitory doses in the high ng/ml range. Microscopic studies of PsV inhibition by the alpha-defensins revealed that they block virion escape from endocytic vesicles but not virion binding or internalization. Consistent with this finding, PsVs remained susceptible to inhibition by alpha-defensins for many hours after initial binding to cells. HNPs 1-3 and HD-5 have been reported to be present in the female genital tract at levels that overlap those that inhibit HPVs in vitro, suggesting that they could present a natural barrier to the sexual transmission of HPV and could serve as the basis of a broad-spectrum topical microbicide.

Cross-neutralization of cutaneous and mucosal Papillomavirus types with anti-sera to the amino terminus of L2

Vaccination with papillomavirus L2 has been shown to induce neutralizing antibodies that protect against homologous type infection and cross-neutralize a limited number of genital HPVs. Surprisingly, we found that antibodies to bovine papillomavirus (BPV1) L2 amino acids 1-88 induced similar titers of neutralizing antibodies against Human papillomavirus (HPV)16 and 18 and BPV1 pseudoviruses and also neutralized HPV11 native virions. These antibodies also neutralized each of the other pseudovirus types tested, HPV31, HPV6 and Cottontail rabbit papillomavirus (CRPV) pseudoviruses, albeit with lower titers. HPV16, HPV18, HPV31, HPV6 and CRPV L2 anti-sera also displayed some cross-neutralization, but the titers were lower and did not encompass all pseudoviruses tested. This study demonstrates the presence of broadly cross-neutralizing epitopes at the N-terminus of L2 that are shared by cutaneous and mucosal types and by types that infect divergent species. BPV1 L2 was exceptionally effective at inducing cross-neutralizing antibodies to these shared epitopes.

Maturation of papillomavirus capsids

The papillomavirus capsid is a nonenveloped icosahedral shell formed by the viral major structural protein, L1. It is known that disulfide bonds between neighboring L1 molecules help to stabilize the capsid. However, the kinetics of inter-L1 disulfide bond formation during particle morphogenesis have not previously been examined. We have recently described a system for producing high-titer papillomavirus-based gene transfer vectors (also known as pseudoviruses) in mammalian cells. Here we show that papillomavirus capsids produced using this system undergo a maturation process in which the formation of inter-L1 disulfide bonds drives condensation and stabilization of the capsid. Fully mature capsids exhibit improved regularity and resistance to proteolytic digestion. Although capsid maturation for other virus types has been reported to occur in seconds or minutes, papillomavirus capsid maturation requires overnight incubation. Maturation of the capsids of human papillomavirus types 16 and 18 proceeds through an ordered accumulation of dimeric and trimeric L1 species, whereas the capsid of bovine papillomavirus type 1 matures into more extensively cross-linked forms. The presence of encapsidated DNA or the minor capsid protein, L2, did not have major effects on the kinetics or extent of capsid maturation. Immature capsids and capsids formed from L1 mutants with impaired disulfide bond formation are infectious but physically fragile. Consequently, capsid maturation is essential for efficient purification of papillomavirus-based gene transfer vectors. Despite their obvious morphological differences, mature and immature capsids are similarly neutralizable by various L1- and L2-specific antibodies.

Infrared spectra of the Cl––C2H4 and Br––C2H4 anion dimers

Infrared spectra of mass-selected Cl- -C2H4 and Br- -C2H4 complexes are recorded in the vicinity of the ethylene CH stretching vibrations (2700-3300 cm(-1) using vibrational predissociation spectroscopy. Spectra of both complexes exhibit 6 prominent peaks in the CH stretch region. Comparison with calculated frequencies reveal that the 4 higher frequency bands are associated with CH stretching modes of the C2H4 subunit, while the 2 weaker bands are assigned as overtone or combinations bands gaining intensity through interaction with the CH stretches. Ab initio calculations at the MP2/aug-cc-pVDZ level suggest that C2H4 preferentially forms a single linear H-bond with Cl- and Br- although a planar bifurcated configuration lies only slightly higher in energy (by 110 and 16 cm(-1), respectively). One-dimensional potential energy curves describing the in-plane intermolecular bending motion are developed which are used to determine the corresponding vibrational energies and wavefunctions. Experimental and theoretical results suggest that in their ground vibrational state the Cl- -C2H4 and Br- -C2H4 complexes are localized in the single H-bonded configuration, but that with the addition of modest amounts of internal energy, the in-plane bending wavefunction also has significant amplitude in the bifurcated structure.

Reactivity of human sera in a sensitive, high-throughput pseudovirus-based papillomavirus neutralization assay for HPV16 and HPV18

Sensitive high-throughput neutralization assays, based upon pseudoviruses carrying a secreted alkaline phosphatase (SEAP) reporter gene, were developed and validated for human papillomavirus (HPV)16, HPV18, and bovine papillomavirus 1 (BPV1). SEAP pseudoviruses were produced by transient transfection of codon-modified papillomavirus structural genes into an SV40 T antigen expressing line derived from 293 cells, yielding sufficient pseudovirus from one flask for thousands of titrations. In a 96-well plate format, in this initial characterization, the assay was reproducible and appears to be as sensitive as, but more specific than, a standard papillomavirus-like particle (VLP)-based enzyme-linked immunosorbent assay (ELISA). The neutralization assay detected type-specific HPV16 or HPV18 neutralizing antibodies (titers of 160-10240) in sera of the majority of a group of women infected with the corresponding HPV type, but not in virgin women. Sera from HPV16 VLP vaccinees had high anti-HPV16 neutralizing titers (mean: 45000; range: 5120-163840), but no anti-HPV18 neutralizing activity. The SEAP pseudovirus-based neutralization assay should be a practical method for quantifying potentially protective antibody responses in HPV natural history and prophylactic vaccine studies.

Interaction of papillomavirus virus-like particles with human myeloid antigen-presenting cells

Papillomavirus-like particles (VLPs) are potent inducers of humoral and cellular immune responses, making them attractive candidates for noninfectious viral subunit vaccines. To further our understanding of how VLPs activate the immune system, we have investigated their interaction with human myeloid antigen-presenting cells. We found that VLPs bound, with increasing density, to the cell surface of human monocytes, macrophages, and monocyte-derived dendritic cells (DCs). Interestingly, there was a negative correlation between binding intensity and CD83 expression in DCs, suggesting that the main receptor for binding of VLPs may be downregulated during maturation. Exposure to VLPs resulted in acute phenotypic activation of monocytes and DCs. Furthermore, VLPs rapidly induced production of inflammatory cytokines in monocytes, macrophages, and DCs, as assessed by intracellular cytokine staining. For each cell type, the patterns of interleukin-1beta, interleukin-12, tumor necrosis factor-alpha, and interleukin-6 production were distinct from the pattern induced by lipopolysaccharide (LPS), a bacterial activator of myeloid antigen-presenting cells. Our results indicate that VLPs target multiple cells of the immune system, which helps to account for VLPs being so effective in priming humoral and cellular immune responses even in the absence of adjuvant.

NF-kappaB elements contribute to junB inducibility by lipopolysaccharide in the murine macrophage cell line RAW264.7

Macrophages respond to bacterial lipopolysaccharide (LPS) by activating latent cis-acting factors that initiate transcription of immediate early genes. One such immediate early gene, junB, is induced by LPS in macrophages within 30 min. To identify elements that mediate the induction of junB by LPS, upstream and downstream sequences flanking the junB gene were examined by transient expression in the RAW264.7 murine macrophage cell line using a luciferase reporter gene vector containing the junB minimal promoter. A >10-fold enhancement was associated with a 222 bp region downstream of the junB promoter in response to LPS. Transient reporter assays demonstrated that multiple nuclear factor (NF) kappaB sites are required for inducibility of junB by LPS in RAW264.7 cells. Electrophoretic mobility shift assays confirmed binding of LPS-induced nuclear proteins included p50/p65 heterodimers at these NF-kappaB sites.

Medical internet ethics: a field in evolution

As in any new field, the merger of medicine, e-commerce and the Internet raises many questions pertaining to ethical conduct. Key issues include defining the essence of the patient-provider relationship, establishing guidelines and training for practicing online medicine and therapy, setting standards for ethical online research, determining guidelines for providing quality healthcare information and requiring ethical conduct for medical and health websites. Physicians who follow their professional code of ethics are obligated not to exploit the relationship they have with patients, nor allow anyone else working with them to do so. Physicians and therapists are obligated to serve those who place trust in them for treatment, whether in face-to-face or online Internet encounters with patients or clients. This ethical responsibility to patients and clients is often in direct conflict with the business model of generating profits. Healthcare professionals involved in Medical Internet Ethics need to define the scope of competent medical and healthcare on the Internet. The emerging ethical issues facing medicine on the Internet, the current state of medical ethics on the Internet and questions for future directions of study in this evolving field are reviewed in this paper.

Constitutive activation of STAT3 is associated with the acquisition of an interleukin 6-independent phenotype by murine plasmacytomas and hybridomas

Interleukin 6 (IL-6), the major growth factor for myeloma cells, signals through the activation of signal transducers and activators of transcription (STAT) proteins. An important step in the malignant progression of murine plasmacytomas is the transition from dependence on IL-6 to a state of IL-6 independence. To elucidate the mechanism whereby IL-6 independence occurs, intracellular signaling events elicited by IL-6 in both IL-6-dependent and -independent plasmacytomas and hybridomas were compared. It was found that STAT3, a key molecule involved in IL-6 signaling, was constitutively activated and phosphorylated in IL-6-independent cell lines compared to the IL-6-dependent cells. Further comparison of upstream signaling pathways revealed that JAK-1 was constitutively present in anti-phosphotyrosine immunoprecipitates of IL-6-independent cells; gp130 was constitutively phosphorylated in a subset of IL-6-independent plasmacytomas, whereas other IL-6-independent lines showed no detectable gp130 phosphorylation in the absence of exogenous IL-6. Secretion of a factor capable of supporting the growth of IL-6-dependent cells was observed in one of the IL-6-independent plasmacytomas, but not in others, making an autocrine mechanism an unlikely explanation for IL-6 independence. These findings provide evidence that the constitutive activation of STAT3, either in the absence of detectable receptor-proximal events or associated with the concomitant activation of gp130, can contribute to the process of IL-6 independence.

The synthesis, in vitro reactivity, and evidence for formation in humans of 5-phenyl-1,3-oxazinane-2,4-dione, a metabolite of felbamate

Previously we have proposed and provided evidence for a metabolic scheme leading to 3-carbamoyl-2-phenylpropionaldehyde from the antiepileptic drug felbamate. This aldehyde was found to undergo reversible cyclization to form the more stable cyclic carbamate 4-hydroxy-5-phenyl-tetrahydro-1,3-oxazin-2-one or undergo elimination to form 2-phenylpropenal. The cyclic carbamate bears structural similarity to 4-hydroxycyclophosphamide and there is an intriguing parallelism between the pathway from the cyclic carbamate to 2-phenylpropenal and the known pathway from 4-hydroxycyclophosphamide to acrolein. The similarity of these transformations led us to consider 5-phenyl-1,3-oxazinane-2,4-dione, which could arise from an oxidation of the cyclic carbamate, as a potential metabolite of felbamate. As the formation of this dione species may have both potential pharmacologic and toxicologic implications for felbamate therapy, we wished to study its reactivity. We have developed a synthesis of 5-phenyl-1, 3-oxazinane-2,4-dione and evaluated its reactivity in vitro. This dione was found to undergo base-catalyzed decomposition to three products, one of which is the major human metabolite of felbamate, 3-carbamoyl-2-phenylpropionic acid. Furthermore, we have found evidence for the presence of the dione in human urine after felbamate treatment through the identification of its major in vitro decomposition product, 2-phenylacrylamide 11.

Evaluation of methods for transient transfection of a murine macrophage cell line, RAW 264.7

Monocyte/macrophage cell lines are fastidious cells commonly used in transient transfection experiments. In the course of a study of gene regulation by lipopolysaccharide (LPS), we have compared several methods for DNA-mediated cell transfection to determine which would be optimally applicable to the macrophage line, RAW 264.7. Both the response level (LPS inducibility) and the degree of inter-assay variation were evaluated for each transfection technique. The following methods were compared: Lipofectin, LipofectAMINE, LipofectAMINE PLUS, SuperFect, Ca3(PO4)2 DNA co-precipitation, DEAE dextran-mediated transfection and electroporation. The transfected plasmid DNA included a luciferase reporter construct containing the junB minimal promoter under the control of an LPS-inducible 1300-bp regulatory fragment downstream of junB 5'-flanking sequence, as well as a beta-galactosidase reporter construct under the adenovirus promoter and enhancer used as an internal control. Electroporation, followed by a resting period of 16-24 h before stimulation with LPS, had the highest inducibility of all methods. DEAE dextran and Ca3(PO4)2 precipitation showed the least and the greatest inter-assay variation, respectively. For all other methods, inter-assay variability fell within this range. The results presented may serve as both a general reference and a guide for reporter gene studies in this or other macrophage cell lines.

Quantification in patient urine samples of felbamate and three metabolites: acid carbamate and two mercapturic acids

PURPOSE

Previously we proposed and provided evidence for the metabolic pathway of felbamate (FBM), which leads to the reactive metabolite, 3-carbamoyl-2-phenylpropion-aldehyde. This aldehyde carbamate was suggested to be the reactive intermediate in the oxidation of 2-phenyl-1,3-propanediol monocarbamate to the major human metabolite 3-carbamoyl-2-phenylpropionic acid. In addition, the aldehyde carbamate was found to undergo spontaneous elimination to 2-phenylpropenal, commonly known as atropaldehyde. Moreover, atropaldehyde was proposed to play a role in the development of toxicity during FBM therapy. Evidence for atropaldehyde formation in vivo was reported with the identification of modified N-acetyl-cysteine conjugates of atropaldehyde in both human and rat urine after FBM administration. Identification of the atropaldehyde-derived mercapturic acids in urine after FBM administration is consistent with the hypothesis that atropaldehyde is formed in vivo and that it reacts with thiol nucleophiles. Based on the hypothesis that the potential for toxicity will correlate to the amount of atropaldehyde formed, we sought to develop an analytic method that would quantify the amount of relevant metabolites excreted in patient urine.

METHODS

We summarize the results of an LC/MS method used to quantify FBM, 3-carbamoyl-2-phenylpropionic acid and two atropaldehyde-derived mercapturic acids in the patient population.

RESULTS

Analysis was performed on 31 patients undergoing FBM therapy. The absolute quantities of FBM and three metabolites were measured.

CONCLUSIONS

This method demonstrated sufficient precision for the identification of patients exhibiting "abnormal" levels of atropaldehyde conjugates and may hold potential for patient monitoring.

The synthesis and evaluation of temperature sensitive tubulin toxins

The synthesis of several potent inhibitors of tubulin polymerization that exert their activities through interaction at the colchicine binding site is described. These agents were evaluated for their abilities to inhibit the polymerization of tubulin and the growth of neoplastic cell cultures. Additionally, the inhibition of tubulin polymerization activity of these agents was assessed over a temperature range of 30-45 degrees C to ascertain the effect of temperature on this activity. Several of the compounds possess significant inhibition of tubulin polymerization activity, and select compounds exhibit this activity in a temperature dependent manner.

Potentially reactive cyclic carbamate metabolite of the antiepileptic drug felbamate produced by human liver tissue in vitro

Felbamate (FBM) is a novel antiepileptic drug that was approved in 1993 for treatment of several forms of epilepsy. After its introduction, toxic reactions (aplastic anemia and hepatotoxicity) associated with its use were reported. It is unknown whether FBM or one of its metabolites is responsible for these idiosyncratic adverse reactions. Although the metabolism of FBM has not been fully characterized, three primary metabolites of FBM have been identified, i.e. 2-hydroxy, p-hydroxy, and monocarbamate metabolites. In addition, the monocarbamate metabolite leads to a carboxylic acid, which is the major metabolite of FBM in humans. Formation of the hydroxylated products of FBM involves cytochrome P450 enzymes, but the enzymes involved in the formation and further metabolism of the monocarbamate have not yet been elucidated. Recently, mercapturate metabolites of FBM have been identified in human urine, and a metabolic scheme involving reactive aldehyde metabolite formation from the monocarbamate metabolite has been proposed. The present study confirmed the formation of the proposed metabolites using human liver tissue in vitro. The aldehyde intermediates were trapped as oxime derivatives, and the cyclic equilibrium product (proposed as a storage and transport form for the aldehydes) was monitored directly by HPLC or GC/MS. Formation of putative toxic aldehyde intermediates and the major carboxylic acid metabolite of FBM was differentially effected with the cofactors NADP+ and NAD+. It is possible that the cofactors may influence the relative metabolism via activation and inactivation pathways.

The synthesis and evaluation of benzannelated-azatoxins: the benzazatoxins

The synthesis and evaluation of azatoxin congeners possessing annealed aromatic frameworks are described. The compounds were evaluated for their abilities to affect topoisomerase II inhibition through the stabilization of "cleavable complex" and for the inhibition of tubulin polymerization using purified bovine brain tubulin.

Synthesis and structure-activity profiles of A-homoestranes, the estratropones

2-Methoxyestradiol, a mammalian metabolite of estradiol, has reported antiangiogenic activity which has been proposed to be mediated through interaction at the colchicine binding site on the tubulin monomer. Subsequent structure-activity studies of 2-methoxyestradiol have yielded highly potent steroidal inhibitors of tubulin polymerization. In an effort to probe the scope of binding at the colchicine binding site and the nature of the relationship between 2-methoxyestradiol and colchicine, a series of colchicine/2-methoxyestradiol hybrids was synthesized. These A-homoestrane hybrid systems, collectively termed estratropones, possessed an A-ring tropone system with the keto functionality at either the C-2, C-3, or C-4 position of the steroid nucleus. The estratropones were evaluated for their ability to inhibit the polymerization of tubulin using an in vitro purified bovine brain assay. Most of these hybrids inhibit polymerization with greater potency than either of the natural products. The most potent of these congeners possessed an approximate 5-fold enhancement of the activity of colchicine for the inhibition of tubulin polymerization. alpha-Substituents on the tropone ring showed varied effects on the activities for the two classes of estratropones studied in this regard, the C-3 oxo and the C-4 oxo species. The 3-substituted 4-oxoestratropones exhibited antitubulin activity according to Cl approximately Br > OCH3, whereas the 4-substituted 3-oxoestratropones exhibited activity according to OCH3 > Br approximately Cl. It is unclear if these substituent factors are purely electronic or steric effects or if the substituent operates indirectly by altering the conformation of the nonplanar troponoid ring. The estratropones represent a new class of tubulin binding agents with potential antiangiogenic utility.

A proposed mechanism for p-aminoclonidine allergenicity based on its relative oxidative lability

p-Aminoclonidine (apraclonidine) is a selective alpha 2 adrenergic agonist used to reduce intraocular pressure in the treatment of glaucoma. Use of apraclonidine is frequently associated with severe local allergic effects which warrant discontinuation of the drug in affected patients. We have assessed the oxidative lability of apraclonidine relative to a panel of adrenergic agonists and/or known allergens; amodiaquine, epinephrine, clonidine, and brimonidine. These compounds were compared by their electrochemical potentials as well as their oxidative lability in the presence of several oxidative enzyme systems (i.e., horseradish peroxidase, lactoperoxidase, myeloperoxidase, and diamine oxidase). The half-lives for enzymatic oxidation of these compounds were found to parallel the electrochemical oxidation potentials in the order: amodiaquine approximately epinephrine < apraclonidine << clonidine approximately brimonidine. The production of a reactive electrophilic intermediate of apraclonidine was demonstrated through the formation of two glutathione apraclonidine adducts from the horseradish peroxidase/H2O2-mediated oxidation of apraclonidine in the presence of glutathione. A mechanism for apraclonidine allergenicity in vivo is proposed wherein apraclonidine is bioactivated through oxidation to the bis-iminoquinone followed by protein conjugation to form an apraclonidine-protein hapten that elicits the immune response.

Mechanisms of adrenergic agonist induced allergy bioactivation and antigen formation

Reduction of elevated intraocular pressure with alpha 2 agonists has proved to be an exciting new therapeutic approach for the treatment of glaucoma. We have studied the chemical reactivities of several alpha 2 agonists and known allergens to elucidate the origin of the observed ocular allergic response to the alpha 2 agonist apraclonidine. The oxidation potentials of clonidine, apraclonidine, brimonidine, and two known allergens, amodiaquine, and epinephrine, were measured vs. a standard calomel electrode.. Agents that were oxidatively labile were treated with both chemical and enzymatic oxidants. Clonidine and brimonidine proved to be oxidatively stable in sharp contrast to apraclonidine which had an oxidation potential similar to that observed with epinephrine and amodiaquine, two known allergy-inducing agents. In addition, two glutathione-apraclonidine conjugates formed by the in-situ reaction of glutathione with an enzymatically oxidized apraclonidine intermediate were isolated and their structures determined using spectroscopic methods. The structures were shown to be analogous to those obtained with amodiaquine and epinephrine. Apraclonidine, like amodiaquine and epinephrine, possesses a hydroquinone-like subunit and can be readily oxidized and conjugated with thiols modeling well known hapten-forming reactions. Brimonidine, like clonidine, lacks the hydroquinone subunit and does not undergo the thiol conjugation reactions.

Identification of modified atropaldehyde mercapturic acids in rat and human urine after felbamate administration

3-Carbamoyl-2-phenylpropionaldehyde has recently been proposed [Thompson et al. (1996) Chem. Res. Toxicol. 9, 1225-1229] as a potential reactive metabolite of the anti-epileptic drug felbamate. This aldehyde was found to undergo rapid elimination to generate 2-phenylpropenal and reversible cyclization to generate 4-hydroxy-5-phenyltetrahydro-1,3-oxazin-2-one at physiological pH. 2-Phenylpropenal, an alpha,beta-unsaturated aldehyde commonly termed atropaldehyde, is a potent electrophile and undergoes rapid conjugation with glutathione. We sought to demonstrate the formation of atropaldehyde in vivo through the identification of mercapturic acids in rat and human urine after felbamate administration. In this paper, we describe the identification of both the reduced (N-acetyl-S-(2-phenylpropan-3-ol)-L-cysteine) and oxidized (N-acetyl-S-(2-phenyl-3-propanoic acid)-L-cysteine) mercapturic acids of atropaldehyde in rat and human urine. The reduced species was the more abundant in human (approximately 2:1) and rat (approximately 6:1) urine. These findings establish the possibility that atropaldehyde is formed from felbamate in vivo, undergoes glutathione conjugation, and is ultimately excreted in urine in the form of mercapturic acids. Thus, the proposed pathway of felbamate biotransformation, if confirmed in patients, could contribute to our understanding of the toxicities observed during felbamate treatment.

Synthesis and in vitro reactivity of 3-carbamoyl-2-phenylpropionaldehyde and 2-phenylpropenal: putative reactive metabolites of felbamate

We propose that 3-carbamoyl-2-phenylpropionaldehyde is an intermediate in the metabolism of felbamate, an anti-epileptic drug with a unique profile of the therapeutic activity, and undergoes a cascade of chemical reactions responsible for the toxic properties of the parent drug. To test this hypothesis, we have synthesized 3-carbamoyl-2-phenylpropionaldehyde and evaluated its in vitro reactivity. This molecule was found to be highly unstable at physiological pH (t1/2 < or = 30 s) and to undergo facile elimination to 2-phenylpropenal, an alpha, beta-unsaturated aldehyde commonly termed atropaldehyde. However, the predominant reaction pathway for 3-carbamoyl-2-phenylpropionaldehyde was reversible cyclization to generate 4-hydroxy-5-phenyltetrahydro-1,3-oxazin-2-one, a urethane that has a considerably longer half-life at physiological pH (t1/2 > or = 5 h) and may serve as a stable reservoir of the reactive aldehyde both in vitro and in vivo. Atropaldehyde is a potent electrophile and was found to exhibit cytotoxicity to cultured fibroblasts (50% growth inhibition (GI50) = 4.1 +/- 1.1 microM) comparable to the known unsaturated aldehyde toxins, 4-hydroxy-2-nonenal and acrolein. 3-Carbamoyl-2-phenylpropionaldehyde also exhibited significant cytotoxicity (GI50 = 53 +/- 8 microM), whereas 2-phenyl-1,3-propanediol monocarbamate (GI50 > 500 microM) and 3-carbamoyl-2-phenylpropionic acid (GI50 > 500 microM) were nontoxic. We have additionally demonstrated the formation of a glutathione-atropaldehyde conjugate from the in vitro incubation of 3-carbamoyl-2-phenylpropionaldehyde with glutathione. Thus, the potent cytotoxicity and potential allergenicity of atropaldehyde implicate this unsaturated aldehyde as a possible causative agent in the toxicities observed with felbamate treatment.

Use of GnRH agonist before hysterectomy: a cost simulation

OBJECTIVE

To evaluate the potential savings in cost of care derived from performing vaginal hysterectomies instead of abdominal hysterectomies in selected women with fibroid uteri equivalent in size to a 14-18 week gestation.

METHODS

Women 35-46 years of age undergoing hysterectomy for fibroid uteri were selected to allow application of conversion rates gained in a separate randomized study using leuprolide acetate depot 3.75 mg. Statewide public data for North Carolina's hospital discharges provided relative rates of hospital charges and leiomyomas for all hysterectomies, by age. Professional charges were omitted from the analysis. Estimated savings were projected to the national level.

RESULTS

During 1992 in North Carolina, 18,110 inpatient hysterectomies were performed for women of all ages; 28.1% of these were for uterine leiomyomas. For women 35-46 years old (12.7% of all hysterectomies), there were 1904 abdominal and 390 vaginal hysterectomies; the mean total charge for abdominal hysterectomy was $5590, and $4732 for the vaginal alternative. These statewide data provide missing elements to allow a national estimate of the potential savings of using GnRH agonist preoperatively. The projected national savings, if 1987 utilization data are used, was $4.6 million, nearly 1.4% of the inpatient charges. The 1992 value of these savings is $6.7 million.

CONCLUSION

The use of preoperative GnRH agonist therapy before hysterectomy for patients with a uterine size equivalent to a 14-18 week gestation represents a significant cost-saving alternative, increasing the use of vaginal hysterectomy and resulting in potential savings in direct inpatient medical care charges.

Cold induced rhabdomyolysis in carnitine palmyityl transferase deficiency

A case of carnitine palmityl transferase deficiency in skeletal muscle is described. The usual symptoms associated with this disease (recurrent muscle cramps or pain and pigmenturia) were observed but sudden exposure to cold precipitate rhabdomyolysis in this patient.

Symptomatic hypergastrinaemia with achlorhydria: reflief by antrectomy

A women had hypergastrinaemia associated with the variety of gastritis (Type A) that is associated usually with pernicious anaemia, together with recurring bouts of severe abdominal pain. Fasting serum gastrin levels ranged between 600 and 2750 pg/ml. There was a rise in serum gastrin levels after a standard protein meal, indicative of a large G cell mass, and a fall after intragastric HCI, which led to a trial of treatment with HCI; this gave some symptomatic relief. After surgical antrectomy there was a profound fall of serum gastrin from a pre-operative level of 2500 pg/ml to constant values of 16--25 pg/ml, and complete and lasting relief from the bouts of abdominal pain.

Quantitation of cell-mediated immunity: responses to dinitrochlorobenzene and ubiquitous antigens

T-lymphocyte immune capacity in man was assessed semiquantitatively by two in vivo procedures: the primary type of response to dinitrochlorobenzene and the secondary type of response, representing memory, to a group of five uniquitous antigens. Controlling for degree of illness proved important in assessing immune capacity in specific diseases; thus, the number of responders and mean score of semiquantitated responses was significantly lower in groups of patients with cancer and multisystem autoimmune disease when comparisons were made with healthy persons, but less so when comparisons were made with a group of subjects with other incapacitating diseases. A notable finding was the lack of correlation in the results of tests of cell-mediated immunity between the two procedures described. Depressed cell-mediated immunity shown in multisystem autoimmune disease is relevant to both predisposition to infection and the postulated role of thymic dysfunction in the pathogenesis of autoimmunity.

Human infection with a tapeworm, Bertiella sp., probably of African origin

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