Use of antithrombotic therapy for secondary prevention in patients with stable atherosclerotic cardiovascular disease: Insights from the COordinated National Network to Engage Cardiologists in the antithrombotic Treatment of patients with CardioVascular Disease (CONNECT-CVD) study

BACKGROUND

Although acetylsalicylic acid is the most commonly used antithrombotic agent for the secondary prevention of cardiovascular events, residual atherothrombotic risk has prompted a guideline recommendation for the addition of dual antiplatelet therapy (DAPT) or dual pathway inhibition (DPI) in high vascular risk patients. Accordingly, the CONNECT CVD quality enhancement initiative provides a contemporary "snapshot" of the clinical features and antithrombotic management of atherosclerotic cardiovascular disease (ASCVD) patients in Canada.

METHODS

Canadian cardiologists (49 cardiologists from six provinces) undertook a retrospective chart audit of 10 ASCVD patients in their outpatient practice who met the Cardiovascular Outcomes for People Using Anticoagulation Strategy-like criteria from May 2018 to April 2019.

RESULTS

Of the 492 (two cardiologists provided 11 patients) enroled, average age was 70 years, 25% were female, 39% had diabetes and 20% had atrial fibrillation. Prior revascularisation was common (percutaneous coronary artery intervention 61%, coronary artery bypass graft 39%), with 31% having multivessel disease. A total of 47% of patients had a Reduction of Atherothrombosis for Continued Health bleeding score of ≥11 (~2.8% risk of serious bleeding at 2 years). Single antiplatelet therapy (SAPT) alone was most commonly used (62%), while 22% were on DAPT alone. In total, 22% were on oral anticoagulation (OAC), with 16% being on non-vitamin K oral anticoagulant alone, 5% on DPI and 1% received triple therapy.

CONCLUSIONS

In contemporary Canadian clinical practice of stable ASCVD patients, a large number of patients receive antithrombotic therapy other than SAPT. Further efforts are required to guide the appropriate selection of patients in whom more potent antithrombotic therapies may safely reduce residual risk.

Difference between the abilities of human Fcgamma receptor-expressing CV-1 cells to neutralize American and Asian genotypes of dengue virus 2

Sera from patients involved in a Peruvian outbreak of dengue virus serotype 1 infection cross-neutralized the American genotype of dengue virus serotype 2 up to 100-fold more efficiently than they did the virulent Asian genotype of dengue virus serotype 2, as determined by a plaque reduction neutralization test (PRNT) with CV-1 fibroblasts modified to express human Fcgamma receptor CD32. The concordant preferential immune enhancement of the Asian genotype of dengue virus serotype 2 in human monocytes suggests that such a modification might strengthen the correlation between the PRNT titer and protection.

Expression of Human papillomavirus type 16 major capsid protein in transgenic Nicotiana tabacum cv. Xanthi

The production of vaccine antigens in plants is a safe and potentially very cost-effective alternative to traditional expression systems. We investigated the possibility of transgenic plant expression of the Human papillomavirus (HPV) type 16 L1 major capsid protein, with and without nuclear localisation signals, in Nicotiana tabacum cv. Xanthi plants. The genes were stably integrated into the N. tabacum genome, and both the expressed proteins were capable of assembling into capsomers and virus-like particles. The proteins in concentrated leaf extracts (L1(Tr)) were tested for antigenicity using a panel of characterised monoclonal antibodies (Mabs). Neutralising and conformation-specific Mabs (H16:V5 and H16:E70) were shown to bind to both types of the plant-produced particles. We estimated the L1(Tr) product yield to be 2-4 microg per kg of fresh leaf material. Rabbits immunised with small doses of plant-produced particles elicited a weak anti-HPV-16 L1 immune response. Our results support the feasibility of using transgenic plants for the production of HPV vaccines.

Oral antibodies to human papillomavirus type 16 in women with cervical neoplasia

This study investigated the relationship between human papillomavirus type 16 (HPV-16) antibodies detected in oral fluid from women with cervical neoplasia, their HPV-16 antibody seroprevalence, and their cervical HPV-16 DNA presence. Cervical HPV-16 DNA was detected by polymerase chain reaction in 43.2% (35/81) of these women. The prevalence of IgG and IgA antibodies to HPV-16 virus-like particles (VLP-16) in oral fluid and was investigated by enzyme-linked immunosorbent assay. Anti-VLP-16 IgA antibodies were detected in oral fluid from 54.3% (44/81) of women with cervical neoplasia, compared with 8% (3/36) in controls (P = 0.000002). Anti-VLP-16 IgG was detected in oral fluid from 43.2.9% (25/72) and 13.3% (4/30; P = 0.029), respectively. Women who were HPV-16 DNA positive at their cervical lesion, displayed an oral fluid anti-VLP-16 IgA prevalence of 60.7% (17/28) and HPV-16 DNA negative women an oral fluid anti-VLP-16 IgA prevalence of 50% (20/40; P = 0.38). Oral fluid anti-VLP-16 IgG prevalence in HPV-16 DNA positive women was 28.6% (8/28) compared with 40% (16/40) in oral fluid from HPV-16 DNA negative women (P = 0.3). Amongst HPV-16 DNA positive women, the anti-VLP-16 IgG seroprevalence was 75% (21/28) and IgA seroprevalence 35.7% (10/28) and for the HPV-16 DNA negative women these values were 60% (24/40) and 32.5% (13/40), respectively. Oral IgA antibody testing proved no more sensitive than serum antibody detection for the determination of HPV infection but could be useful as a non-invasive screening method for women with cervical neoplasia and for estimating the mucosal antibody response to HPV vaccines.

A Phase 1 study of a recombinant viruslike particle vaccine against human papillomavirus type 11 in healthy adult volunteers

Viruslike particles (VLPs) produced from the L1 protein of several papillomaviruses have induced protection from infection after live challenge in animal models. In the present study, the safety and immunogenicity of a human papillomavirus (HPV)--11 L1 VLP candidate vaccine were measured in a phase 1, dose-finding trial in humans. The vaccine was well tolerated and induced high levels of both binding and neutralizing antibodies. Marked increases in lymphoproliferation to HPV--11 L1 antigens were noted after the second vaccination. In addition, lymphoproliferation was induced after vaccination in peripheral blood mononuclear cells (PBMC) stimulated with heterologous L1 VLP antigens of HPV types 6 and 16. Statistically significant increases in HPV antigen--specific interferon--gamma and interleukin-5 production were measured from PBMC culture supernatants. This candidate HPV VLP vaccine induced robust B and T cell responses, and T cell helper epitopes appear to be conserved across HPV types.

Human papillomavirus virus-like particles are efficient oral immunogens when coadministered with Escherichia coli heat-labile enterotoxin mutant R192G or CpG DNA

Certain human papillomaviruses (HPVs) cause most cervical cancer, which remains a significant source of morbidity and mortality among women worldwide. HPV recombinant virus-like particles (VLPs) are promising vaccine candidates for controlling anogenital HPV disease and are now being evaluated as a parenteral vaccine modality in human subjects. Vaccines formulated for injection generally are more costly, more difficult to administer, and less acceptable to recipients than are mucosally administered vaccines. Since oral delivery represents an attractive alternative to parenteral injection for large-scale human vaccination, the oral immunogenicity of HPV type 11 (HPV-11) VLPs in mice was previously investigated; it was found that a modest systemic neutralizing antibody response was induced (R. C. Rose, C. Lane, S. Wilson, J. A. Suzich, E. Rybicki, and A. L. Williamson, Vaccine 17:2129-2135, 1999). Here we examine whether VLPs of other genotypes may also be immunogenic when administered orally and whether mucosal adjuvants can be used to enhance VLP oral immunogenicity. We show that HPV-16 and HPV-18 VLPs are immunogenic when administered orally and that oral coadministration of these antigens with Escherichia coli heat-labile enterotoxin (LT) mutant R192G (LT R192G) or CpG DNA can significantly improve anti-VLP humoral responses in peripheral blood and in genital mucosal secretions. Our results also suggest that LT R192G may be superior to CpG DNA in this ability. These findings support the concept of oral immunization against anogenital HPV disease and suggest that clinical studies involving this approach may be warranted.

Immunological analyses of human papillomavirus capsids

Recombinant human papillomavirus (HPV) virus-like particles (VLPs) are promising vaccine candidates for controlling anogenital HPV disease. Questions remain, however, concerning the extent of capsid antigenic similarity between closely related virus genotypes. To investigate this issue, we produced VLPs and corresponding polyclonal immune sera from several anogenital HPV types, and examined these reagents in enzyme-linked immunosorbent assays (ELISAs) and in cross-neutralization studies. Despite varying degrees of L1 genetic sequence relatedness, VLPs of each type examined induced high-titer serum polyclonal antibody responses that were entirely genotype-specific. In an in vitro infectivity assay, only cognate VLP antisera were able to neutralize pseudovirions of HPV-16, HPV-18 and HPV-33, with two exceptions: HPV-31 and HPV-45 VLP post-immune sera demonstrated low levels of neutralizing activity against pseudovirions of HPV-33 and HPV-18, respectively. In other experiments, epitopes shared between closely related types were found to be less immunogenic than, and antigenically distinct from, primary type-specific B-cell determinants of the viral capsid. In addition, results from epitope blocking experiments suggested a close correlation between primary type-specific capsid antigenic sites and virion neutralization. These findings support the view that papillomavirus genotypes denote unique viral serotypes, and suggest that a successful vaccine for these viruses will likely require the inclusion of VLPs of each serotype for which protection is desired.

The impact of human immunodeficiency virus type 1 status on human papillomavirus (HPV) prevalence and HPV antibodies in serum and cervical secretions

Human immunodeficiency virus (HIV) type 1-infected (HIV-positive) and -uninfected (HIV-negative) sex workers were examined for the presence of cervical human papillomavirus (HPV) DNA. Cervicovaginal rinse and serum samples from these women were examined for IgG and IgA antibodies to HPV-16 virus-like particles (VLP-16) by ELISA. The HIV-positive women displayed a significantly higher prevalence of HPV DNA (40/47 [85%]) than did the HIV-negative women (22/52 [42%]; P=.00001). Both HIV-positive and HIV-negative sex workers displayed a high seroprevalence rate for anti-VLP-16 IgG antibodies (27/40 [68%] and 30/43 [70%], respectively), but significantly fewer HIV-positive women than HIV-negative women had anti-VLP-16 serum IgA (6/40 [15%] vs. 17/43 [40%], respectively; P=.012). Significantly more HIV-positive women than HIV-negative women had cervical anti-VLP-16 IgG antibodies (16/49 [33%] vs. 6/63 [10%], respectively; P=.002) but not IgA antibodies (P=.3).

Nuclear import and DNA binding of human papillomavirus type 45 L1 capsid protein

During the life cycle of human papillomaviruses (HPVs), the L1 capsid proteins seem to enter the nucleus twice: once after the virions infect the cells, and later during the productive phase when they assemble the replicated HPV genomic DNA into infectious virions. We established for the high-risk HPV45 that when digitonin-permeabilized HeLa cells were incubated with L1 homopentameric capsomers, the HPV45 L1 protein was imported into the nucleus in a receptor-mediated manner. In contrast, intact capsids were not able to enter the nucleus. Immunoisolation assays showed that HPV45 L1 capsomers interact with cytosolic karyopherin alpha 2 beta 1 heterodimers. HPV45 L1 bound strongly to karyopherin alpha 2, and weakly to karyopherin beta 1, as did its nuclear localization signal (NLS). Nuclear import of HPV45 L1, or of a GST-NLS(HPV45L1) fusion protein was efficiently mediated by karyopherin alpha 2 beta 1 heterodimers, and only weakly by karyopherin beta 1. Nuclear import required RanGDP, but was independent of GTP hydrolysis by Ran. Together, these data suggest that the major nuclear import pathway for HPV45 L1 major capsid protein in infected host cells is mediated by karyopherin alpha 2 beta 1 heterodimers and that GTP hydrolysis by Ran is not required for import. Remarkably, HPV45 L1 capsomers can interact nonspecifically with different types of HPV-DNA, and the DNA binding region of HPV45 L1 overlaps with its NLS sequence.

Seroresponses to human papillomavirus types 16, 18, 31, 33, and 45 virus-like particles in South African women with cervical cancer and cervical intraepithelial neoplasia

The aim of the study was to determine the prevalence of antibodies to human papillomavirus (HPV) types 16, 18, 31, 33, and 45 in woman in Cape Town with cervical intraepithelial neoplasia (CIN) (n = 95), cervical cancer (n = 40), female blood donors (n = 95) and children (n = 110). The enzyme-linked immunosorbent assay (ELISA) made use of baculovirus synthesised HPV virus like particles (VLPs) as antigen. Antibodies to at least one HPV type were detected in sera from 75% of cancer patients, 71.6% of CIN patients, 44.2% of blood donors and 27.3% of children. Sera from 95 women with CIN were compared with age-matched female blood donors. There was a significant association of seropositivity to VLP-16 (P = 0.006) and VLP-45 (P = 0.008) with CIN compared with the blood donors. There was also a significant difference in the seropositivity of women with CIN to any of the five virus-like particle (VLP) types compared to the blood donors (P = 0.0002: OR = 3.2). Thirty-nine of sixty-nine (56.5%) women with CIN were found to be HPV-16 DNA positive. The average age of women in this group that were VLP-16 seropositive was 34 years and those found to be VLP-16 seronegative was 52 years of age. Antibodies to all five VLP types were detected in these populations, thus an ideal vaccine should induce protection from infection by a wide range of HPV types.

Seroresponses to virus-like particles of human papillomavirus types 16, 18, 31, 33, and 45 in San people of Southern Africa

Virus-like particles (VLPs) of the high-risk human papillomavirus (HPV) types 16, 18, 31, 33, and 45 were used as antigen in enzyme-linked immunosorbent assay (ELISA) to determine the prevalence of serum IgG in a group of San people originally from Namibia, now residing in South Africa. The San children had low seroprevalence to all VLP types, but 26/115 (22.6%) of the children were seropositive to at least 1 VLP type. Among the adults, seroprevalence was significantly higher. The seroprevalence of antibodies in 101 San women to VLP-16 was 16.8%, VLP-18 18.8%, VLP-31 12.9%, VLP-33 17.8%, and VLP-45 22.8%. Five of the 11 men were seropositive: 2 for VLP-31, 1 for VLP-18, 1 for VLP-33, and 1 for VLP-45. Seroreactivity appeared to be type specific, except possibly to VLP-18 and -45. Of the adults, 50.5% were seropositive to at least 1 VLP type and 24.8% were seropositive to >1 VLP type. From this study, it is concluded that the San people are exposed to HPV-16, -18, -31, -33, and -45, with antibodies to VLP-45 being the most prevalent.

Nuclear import of HPV11 L1 capsid protein is mediated by karyopherin alpha2beta1 heterodimers

L1 major capsid proteins of human papillomaviruses (HPVs) enter the nuclei of host cells at two times during the viral life cycle: 1) after infection and 2) later during the productive phase, when they assemble the replicated HPV genomic DNA into infectious virions. L1 proteins are stable in two oligomeric configurations: as homopentameric capsomers, and as capsids composed of 72 capsomers. We found that intact L1 capsids of HPV type 11 cannot enter the nucleus, suggesting that capsid disassembly may be required for HPV11 L1 nuclear import. We established that HPV11 L1 is imported in a receptor-mediated manner into the nuclei of digitonin-permeabilized HeLa cells. HPV11 L1 docked at the nuclear pore complexes via karyopherin alpha2beta1 heterodimers. Anti-karyopherin-beta1 and anti-karyopherin alpha2 antibodies specifically inhibited nuclear import of HPV11 L1. Moreover, nuclear import of HPV11 L1 could be reconstituted using karyopherin alpha2, beta1, RanGDP and p10. In agreement with the docking and import data, we found that HPV11 L1 binds to karyopherin alpha2 and that this interaction is inhibited by a peptide representing the classical nuclear localization signal of SV40 T antigen. These results strongly suggest that HPV11 L1 enters the nucleus of the infected host cell via the karyopherin alpha2beta1 pathway.

Glutathione-dependent ascorbate recycling activity of rat serum albumin

An efficient regeneration of vitamin C (ascorbate) from its oxidized byproduct, dehydroascorbate (DHAA), is necessary to maintain sufficient tissue levels of the reduced form of the vitamin. Additionally, the recycling may be more significant in mammals, such as guinea pigs and humans, who have lost the ability to synthesize ascorbate de novo, than it is in most other mammals who have retained the ability to synthesize the vitamin from glucose. Both a chemical and an enzymatic reduction of DHAA to ascorbate have been proposed. Several reports have appeared in which proteins, including thioltransferase, protein disulfide isomerase, and 3-alpha-hydroxysteroid dehydrogenase, characterized for other activities have been identified as having DHAA reductase activity in vitro. Whether these previously characterized proteins catalyze the reduction of DHAA in vivo is unclear. In the present study, a 66 kD protein was purified strictly on the basis of its DHAA-reductase activity and was identified as rat serum albumin. The protein was further characterized and results support the suggestion that serum albumin acts as an antioxidant and exerts a significant glutathione-dependent DHAA-reductase activity that may be important in the physiologic recycling of ascorbic acid.

Oral vaccination of mice with human papillomavirus virus-like particles induces systemic virus-neutralizing antibodies

To assess whether oral vaccination against human papillomavirus (HPV) may be feasible, we administered HPV virus-like particles (VLPs) to mice by gavage. Enzyme-linked immunosorbent assay (ELISA) results indicated that serum anti-VLP immunoglobulin G (IgG) and IgA antibodies were induced after oral vaccination, and these responses demonstrated antigenic specificities that were conformationally dependent and restricted according to HPV genotype. Importantly, orally induced postimmune sera were found to neutralize HPV-11 virions in vitro. These results indicated that the VLPs were antigenically stable in the environment of the gastrointestinal tract and were able to engage in potentially useful immune system interactions. These findings support the concept of oral vaccination against anogenital HPV disease, and suggest the possibility that this may be a useful approach to the immunization of large populations against cervical cancer and other HPV associated diseases.

Water soluble antioxidants in mammalian aqueous humor: interaction with UV B and hydrogen peroxide

HPLC/electrochemical detection was used to identify five major low MW water soluble electrochemically active molecules from the aqueous humor of three species of mammals: New Zealand White rabbits and humans (diurnal) and Sprague-Dawley rats (nocturnal). These molecules are L-cysteine (CYS), L-ascorbic acid (AA), glutathione (GSH), uric acid (UA) and L-tyrosine (TYR); all of these molecules have known antioxidant properties. Nocturnal rat aqueous humor is concentrated in two thiols: GSH (125 microM; n = 24 pooled eyes) and CYS (63 microM), in contradistinction to diurnal species which have high concentrations of AA. No deterioration of any of these antioxidants occurs in a synthetic aqueous humor mixture irradiated with a physiologically relevant spectral UV B dose of 30 mJ/cm2/h (5.5 UV equivalent sunlight hours). The same result occurred with addition of the endogenous aqueous humor UV B photosensitizer L-tryptophan. In a second set of experiments, human synthetic aqueous humor was subjected to hydrogen peroxide induced oxidant stress. The decay of antioxidants was CYS > GSH > AA > UA > TYR. The second highest concentrated antioxidant in human aqueous humor is TYR. Yet TYR failed to protect AA against H2O2-induced free radical damage in a synthetic aqueous humor model system (P = 0.10; ANOVA). The existence of multiple electrochemically active constituents and their thermodynamic interactions must be recognized when choosing animal models to evaluate human aqueous humor antioxidant defense.

Vitamin supplementation and breast cancer: is homeostasis a factor?

Recent observations by several research groups on many thousands of women have yielded the disappointing view that mega-dose vitamin supplementation does not provide significant protection against breast cancer. This is a review of the pertinent literature with a goal of identifying testable hypotheses that might explain the epidemiology and be helpful in designing subsequent evaluations. In one hypothesis presented, the vitamin content of peripheral cells that protect breast epithelium is not markedly affected by supplementation. In the second hypothesis the metabolic status (redox state) of epithelial cells is more important than the absolute level (reduced plus oxidized) of each antioxidant. In either case, extremes in diet fail to alter inherent homeostatic mechanisms.

Human papillomavirus type 11 recombinant L1 capsomeres induce virus-neutralizing antibodies

The human papillomavirus type 11 (HPV-11) L1 major capsid protein can be trypsinized to generate recombinant capsomeres that retain HPV genotype-restricted capsid antigenicity (M. Li, T. P. Cripe, P. A. Estes, M. K. Lyon, R. C. Rose, and R. L. Garcea, J. Virol. 71:2988-2995, 1997). In the present study, HPV-11 virion-neutralizing monoclonal antibodies H11.F1 and H11.H3, previously characterized as recognizing two distinct HPV-11 capsid-neutralizing antigenic domains (S. W. Ludmerer, D. Benincasa, and G. E. Mark III, J. Virol. 70:4791-4794, 1996), were each found to be highly immunoreactive with trypsin-generated capsomeres in an enzyme-linked immunosorbent assay (ELISA). Capsomeres were used to generate high-titer polyclonal immune sera that demonstrated HPV genotype-restricted reactivity by ELISA. The capsomere antisera were then tested in an in vitro infectivity assay and found to neutralize HPV-11 virions. In this assay, HPV-11 capsomere polyclonal antisera exhibited neutralization titers (10(-5) to 10(-6)) comparable to those obtained with a virion-neutralizing antiserum raised previously against intact HPV-11 VLPs (R. C. Rose, R. C. Reichman, and W. Bonnez, J. Gen. Virol. 75:2075-2079, 1994). These results indicate that highly immunogenic, genotype-restricted HPV capsid-neutralizing antigenic domains are contained entirely within capsomeres. Thus, capsomeres may be viable vaccine candidates for the prevention of HPV disease.

Isolation and propagation of human papillomavirus type 16 in human xenografts implanted in the severe combined immunodeficiency mouse

We report the isolation and propagation of human papillomavirus type 16, the main agent of cervical cancer, using human foreskin fragments implanted in severe combined immunodeficiency mice. The infection produced viral particles, and with each passage of the virus it caused lesions identical to intraepithelial neoplasia, the precursor to carcinoma.

Ocular oxidants and antioxidant protection

Oxidative damage and antioxidant protection in ocular tissues has not been reviewed recently. Metabolism in the eye is of increasing interest because the organ is highly susceptible to damage by sunlight, oxygen, various chemicals, and pollutants. Interest is expected to increase because of an aging Western world population and a continued depletion of stratospheric ozone. Hydrogen peroxide is discussed because it is both a byproduct and a source of free radical reactions and is normally present in the aqueous humor. The metabolism of reactive oxygen species by enzymes, nutrients, pigments, and low molecular weight scavengers is evaluated. Ascorbic acid, because of its high concentration in the eye, is thought to be a primary substrate in ocular protection; progress in determining the mechanisms by which it is recycled and maintained in the useful, reduced state is discussed. Recent information is included about antioxidants not previously known to be present in the eye, and some importance is placed on the properties of the vitreous humor and tear fluid because of the previous lack of emphasis on these.

Tear fluid content of electrochemically active components including water soluble antioxidants

PURPOSE

To describe the content of water-soluble antioxidants in tear fluid.

METHODS

We collected tear fluid from healthy subjects, either into borosilicate glass tubing or by absorption onto Schirmer strips. High pressure liquid chromatography with electrochemical detection provided data on several components in a single assay. The system was sufficiently sensitive to provide reliable values for components present in tear fluid collected at normal (basal) or stimulated rates of secretion.

RESULTS

Tear fluid at basal secretion was found to contain four compounds often considered to function in biology as antioxidants. Ascorbic acid (AA) is found at 665 microM, tyrosine at 45 microM and glutathione (GSH) at 107 microM. Cysteine (48 microM) and uric acid (328 microM) are reported for the first time; the latter is somewhat controversial as a physiologically active antioxidant. One peak on the chromatogram was consistently present but has not been identified. During stimulation of flow by brief inhalation of ammonium hydroxide fumes, the concentration of each compound was lower.

CONCLUSION

This work demonstrates the presence of electro-chemically active components that might function as antioxidants at the anterior surface of the cornea against potential damage from radiation, oxygen toxicity, abrasion and environmental chemicals.

In vitro infection and type-restricted antibody-mediated neutralization of authentic human papillomavirus type 16

Human papillomavirus type 16 (HPV-16) is strongly associated with the development of cervical cancer. Studies of model systems with animal papillomaviruses have demonstrated the importance of neutralizing antibodies in preventing papillomavirus-associated disease. The assessment of neutralizing antibody responses against HPV-16, previously hampered by the lack of a viral source, was enabled by the recent propagation of an HPV-16 stock in xenografted severe combined immunodeficiency (SCID) mice. HPV-16 infection of an immortalized human keratinocyte cell line was demonstrated by detection of an HPV-16-specific spliced mRNA amplified by reverse transcriptase PCR. Infection was blocked by preincubation of the virus with antiserum generated against HPV-16 virus-like particles (VLPs) composed of the major capsid protein, L1. To examine potential cross-neutralizing activity among the different genital HPV types, rabbit antisera to L1 VLPs corresponding to HPV-6, -11, -18, -31, -33, -35, -39, and -45 were assayed for the ability to block the HPV-16 infection of cultured cells. Antiserum raised against HPV-33 L1 VLPs was the only heterologous antiserum which inhibited HPV-16 infection. Thus, a neutralization assay for HPV-16 may help to characterize the components required to compose a broadly efficacious genital HPV vaccine.

Properties of electrochemically active components in mammalian vitreous humor

Antioxidants are considered to have important roles in protecting the eye against radiation, oxygen toxicity and other threats. Several water-soluble electrochemically-active compounds that might function as antioxidants in vitreous humor of rabbit, rat and bovine eyes were identified and quantitated. In that the rat is a nocturnal animal species and the other two are diurnal, the results allow a tentative evaluation on the comparative physiology of light-dark behavior patterns that influence this ocular fluid. All analyses were performed by HPLC with electrochemical detection. The utility of this approach is that components of vitreous humor can be identified by their retention time and by their characteristic response when the voltages of the two sensing electrodes are progressively brought together. Four compounds regarded as functional antioxidants in the animal kingdom were identified and quantitated. Other antioxidants known to be present in several biological fluids are not present at detectable or significant levels in vitreous humor; metabolites or precursors of these might be present in trace quantities.

Serological and T-helper cell responses to human papillomavirus type 16 L1 in women with cervical dysplasia or cervical carcinoma and in healthy controls

In a cross-sectional study we have investigated serological and T-helper (Th) cell responses to human papillomavirus type 16 (HPV-16) L1 in women with HPV-16 related diseases and related them to cervical histology and HPV DNA status. Using a virus-like particle (VLP) based ELISA to detect antibodies to the HPV-16 L1 capsid protein, 45% (33/73) of women with cervical dysplasia, 40% (2/5) of women with cervical cancer, 36% (4/11) of healthy adult female controls and 6% (2/35) of healthy children were found to be seropositive. Amongst women with cervical dysplasia, the highest levels of seropositivity were found in those who were HPV-16 DNA positive (60%, 15/25) or positive for any of the "high-risk' HPV types, 16/18/33 (58%, 18/31), when compared with those with HPV type "X' (25%, 5/20) or with healthy children (6%, 2/35; P < 0.05 for all comparisons). There was a trend for women with cervical dysplasia to show an increased level of seropositivity with increasing grade of lesion. There was no direct correlation found between seropositivity and Th cell responses in all groups studied. However, a combined analysis of each individual's Th and B cell responses suggests that a Th1 pattern of response is predominant amongst healthy adult controls (80% of responders) but reduced in women with cervical dysplasia (55% of responders). A trend towards a decrease in Th1 type responses was also noted with increasing grade of dysplastic lesion. These findings provide further evidence for the importance of the Th response in the control of genital HPV infections.

Expression of the human papillomavirus type 11 L1 capsid protein in Escherichia coli: characterization of protein domains involved in DNA binding and capsid assembly

The L1 major capsid protein of human papillomavirus type 11 (HPV-11) was expressed in Escherichia coli, and the soluble recombinant protein was purified to near homogeneity. The recombinant L1 protein bound DNA as determined by the Southwestern assay method, and recombinant mutant L1 proteins localized the DNA-binding domain to the carboxy-terminal 11 amino acids of L1. Trypsin digestion of the full-length L1 protein yielded a discrete 42-kDa product (trpL1), determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, resulting from cleavage at R415, 86 amino acids from the L1 carboxy terminus. Sucrose gradient sedimentation analysis demonstrated that trpL1 sedimented at 11S, while L1 proteins with amino-terminal deletions of 29 and 61 residues sedimented at 4S. Electron microscopy showed that the full-length L1 protein appeared as pentameric capsomeres which self-assembled into capsid-like particles. The trpL1 protein also had a pentameric morphology but was unable to assemble further. In an enzyme-linked immunosorbent assay, the trpL1 and L1 capsids reacted indistinguishably from virus-like particles purified after expression of HPV-11 L1 in insect cells. The carboxy terminus of L1 therefore constitutes the interpentamer linker arm responsible for HPV-11 capsid formation, much like the carboxy-terminal domain of the polyomavirus VP1 protein. The trypsin susceptibility of HPV-11 L1 capsids suggests a possible mechanism for virion disassembly.

Age distribution of antibodies to human papillomavirus in children, women with cervical intraepithelial neoplasia and blood donors from South Africa

Sera from 95 women with cervical intraepithelial neoplasia (CIN), 95 age-matched female blood donors, and 155 children aged between 1 and 12 years were tested by enzyme-linked immunosorbent assay (ELISA) for levels of serum IgG to three human papillomavirus (HPV) peptides (HPV-16 E2 [E2-16], HPV-18 E2 (E2-18], HPV-16 L1 [L1-16]), as well as HPV-16 virus-like particles (VLP-16) and bovine papillomavirus type 1 virus-like particles (BPV-VLP). In the adult group antibodies to E2-16 and VLP-16 were significantly associated with CIN when compared to the blood donor controls (P = .039 and P = .002, respectively). In women with CIN there was an increase in seropositivity to E2-16 and a decrease in seropositivity to VLP-16 with age. Antibodies to HPV-16 E2 could therefore be an important marker of CIN in women over 40 years of age, whereas antibodies to VLP-16 could be a marker for CIN in younger women. There was no correlation with CIN and antibodies to E2-18, L1-16, and BPV-VLP. In the children's sera antibodies were detected to E2-16 (44.5%), E2-18 (18.7%), L1-16 (20%), VLP-16 (4.5%), and BPV-VLP (5.1%). Between the ages of 3 and 12 years the prevalence of antibodies to E2-16 decreased with age. The presence of antibodies to HPV-16 in young children indicated infection with either HPV-16 or a related virus. HPV DNA isolation from children could help resolve this question.

Infection control to quality improvement: the right time, the right place, the work to be done

Many infection control epidemiologists are moving into the quality improvement field. The marriage of epidemiology with quality improvement is a logical step. Several things have to happen for this union to be successful, however. Most importantly, collaborative relationships must be forged with a variety of healthcare providers and practical, reliable, and valid indicators, and the methods for measuring them must be developed. This will take time, but epidemiologists should insist on and support the development of a robust discipline that combines the best of both worlds.

An apparatus for ultraviolet B irradiation of small volumes of biological fluid under controlled oxygen tension

BACKGROUND

The design, construction, and calibration of a unique apparatus for ultraviolet (UV) B irradiation of small volumes of biological fluid under temperature-controlled open atmospheric or closed cell conditions of defined Po2 is described.

METHODS

The apparatus consists of a custom designed UV transmissible quartz silica 3 port spectrophotometric cuvette coupled to a deuterium UV B source by UV transmissible fiber optics. Fluid movement, temperature regulation, dosimetry, and miniaturized biosensors for oxygen, pH, and temperature are described along with a preliminary experiment.

RESULTS

The apparatus produces a known photochemical effect using an endogenous aqueous humor UV B photosensitizer-L tryptophan. UV B radiation is contained, thus protecting laboratory personnel. The system provides a continuous spectral UV B dose of 30 mJ/cm2/hr, which is equivalent to approximately 5.5 UV sunlight hours reaching an aliquot of mammalian aqueous humor.

CONCLUSIONS

This biophysical apparatus can be used to investigate antioxidant protective systems in ocular fluid (aqueous/vitreous humors and tears), and is also applicable to evaluating the interaction of radiation with ocular and nonocular tissue cell homogenate.

Intestinal absorption of water-soluble vitamins

Vitamin utility is a scientific/medical topic that appears to be pursued as ardently by the lay public as by scientists and medical practitioners. A group of epidemiologists evaluates the effects on health of vitamin intake in the natural diet and by supplementation. The role in ocular disease, cancer of the breast or colon, and cardiovascular disease are a few of the concerns. The results and recommendations concerning dietary vitamin intake will likely continue to change. However, the processes by which dietary vitamins are delivered from intestinal chyme to the blood are more certain. The concept of homeostasis might apply to various of the vitamins as it does to minerals, water, etc. This review will discuss some common methods used to study vitamin absorption and the proposed mechanisms of absorption, and will conclude with a section about dietary regulation.

The potential role of speech production models in automatic speech recognition

This paper investigates the issues that are associated with applying speech production models to automatic speech recognition (ASR). Here the applicability of articulatory representations to ASR is considered independently of the role of articulatory representations in speech perception. While the question of whether it is necessary or even possible for human listeners to recover the state of the articulators during the process of perceiving speech is an important one, it is not considered here. Hence, the authors refrain from posing completely new paradigms for ASR which more closely parallel the relationship between speech production and human speech understanding. Instead, work aimed at integrating speech production models into existing ASR formalisms is described.

Analysis of water-soluble antioxidants by high-pressure liquid chromatography

The measurement of endogenous substances that function as biological antioxidants is of importance because the values obtained might be an index of future health. We quantified three water-soluble antioxidants by high-pressure liquid chromatography with electrochemical detection (h.p.l.c.-e.c.). Current-voltage relationships made at various settings of the D2 porous graphite electrode help to identify ascorbic acid, glutathione and uric acid. The antioxidants are determined simultaneously and without need for derivatization. The method is seen to be useful for comparison of normal rat liver with liver that had undergone oxidative stress through ischaemia. Antioxidant levels in liver, kidney, pancreas and intestinal mucosa are presented and compared with literature values. Endogenous contents of oxidized forms of ascorbic acid and glutathione become apparent following exposure of tissue samples to a strong reductant such as 2-mercapthoethanol.

Serological differentiation of human papillomavirus types 11, 16 and 18 using recombinant virus-like particles

The L1 major capsid protein-coding sequences of human papillomavirus (HPV) types 11, 16 and 18 were expressed in the baculovirus system. Virus-like particles (VLPs) were purified from recombinant-infected Spodoptera frugiperda Sf9 cells and cell-free culture supernatants. Rabbits immunized with purified VLPs developed antibodies that reacted only with the specific VLP type used as the immunogen. In addition, rabbit antibodies raised against infectious HPV-11 virions only reacted with HPV-11 L1 VLPs and not with VLPs derived from either HPV-16 or HPV-18. These results suggest that HPV-11, HPV-16 and HPV-18 virions are antigenically distinct from one another. This observation should be considered in future studies of immune responses to HPV.

Human papillomavirus (HPV) type 11 recombinant virus-like particles induce the formation of neutralizing antibodies and detect HPV-specific antibodies in human sera

Recombinant human papillomavirus type 11 (HPV-11) virus-like particles (VLPs) were tested for their ability to induce the formation of neutralizing antibodies, and were also tested for serodiagnostic capabilities in an ELISA in comparison with HPV-11 whole virions. VLPs, purified by CsCl density gradient centrifugation from the cell-free supernatant of Ac11L1-infected Sf9 suspension cell cultures, were used to immunize rabbits and anti-VLP antibodies were tested in the athymic mouse model of HPV-11 infection. Pretreatment of infectious HPV-11 virions with the immune serum of VLP-treated animals caused a marked reduction of graft growth (P < 10(-4)) and viral gene expression (P < 10(-4)), similar to the effects obtained using whole virion postimmune serum, and consistent with immune neutralization. To assess the serodiagnostic capabilities of VLPs, a VLP ELISA was developed and used to analyse sera that were tested previously in an HPV-11 whole virion ELISA. Specific antibodies were detected in 49% of patients' sera (P = 2 x 10(-4)), and individual VLP seroreactivities correlated with those previously obtained using whole virions as the antigen (r = 0.87; P < 10(-6)). These results indicate that recombinant VLPs can be used to elicit a neutralizing antibody response, and can substitute faithfully for native virions in the development of HPV-serodiagnostic immunoassays.

Evaluation of temperature sensitivity of human papillomavirus type 11 by using the human xenograft severe combined immunodeficiency mouse model

The temperature sensitivity of human papillomavirus type 11 was evaluated by using a human xenograft severe combined immunodeficiency mouse model. Incubation of the virus for 1 h at a temperature higher than 56 degrees C but lower than 72 degrees C was sufficient to inhibit the virally induced growth of infected human tissue. However, 100 degrees C was necessary to completely inactivate HPV type 11 genome expression.

Two E2 binding sites (E2BS) alone or one E2BS plus an A/T-rich region are minimal requirements for the replication of the human papillomavirus type 11 origin

Human papillomaviruses (HPVs) cannot be propagated in vitro, but the DNA can be replicated transiently in an assay in the presence of two trans-acting viral proteins, E1 and E2. Using this assay, we have defined the minimal cis-acting elements of the origin of replication of HPV type 11. Most HPV genomes are conserved at the origin of replication, and the core contains three E2 binding sites (E2BS) surrounding an A/T-rich spacer region. The present results show that the minimal requirement for replication is either two E2BS alone or the A/T-rich region plus one E2BS; in the latter case the relative position of the E2BS is important. In all the studies, the presence of both E1 and E2 proteins was essential for replication, yet only the E2BS was required at the origin. We have shown that E1, E2, and the origin of replication containing an E2BS from a complex in vitro, and our data are consistent with a model in which E2 acts to target E1 to the HPV type 11 replication origin.

Cerebral metabolism of oxidized ascorbate

The brain has a high level of ascorbic acid which is thought to act as a reducing agent, e.g. in protecting tissues against oxidative stress. The mechanism by which ascorbate is maintained in the useful, reduced state in the CNS is evaluated herein. Cerebrum from rat or calf was minced and homogenized in buffer. The endogenous levels of ascorbic acid, dehydro-L-ascorbic acid (DHAA) and reduced glutathione (GSH) were determined by HPLC with coulometric electrochemical detection. We also quantitated tissue capacity to regenerate ascorbic acid from DHAA, which is a product of electron transfer reactions of ascorbic acid. The homogenate was fractionated by centrifugation in steps up to 110,000 x g and dialyzed free of low molecular weight components. The activity for reducing DHAA was approximately equal in the various supernatants; resuspended pellets had little activity. The active component has several properties of a protein, including being precipitated by solid ammonium sulfate addition to the tissue extract; most activity appeared in the 40-80% saturated fraction. The activity was stable up to a temperature of 80 degrees C, but was lost at 95 degrees C. The protein was digested by trypsin. The results suggest that a cytosolic component of cerebrum regenerates ascorbic acid in a step that preferentially uses GSH and NADPH as reducing cofactors. At least one form of DHAA reductase exists in brain.

Propagation of human papillomavirus type 11 in human xenografts using the severe combined immunodeficiency (SCID) mouse and comparison to the nude mouse model

We report propagation of human papillomavirus (HPV) type 11 in human xenografts in the severe combined immunodeficiency (SCID) mouse and compare this new animal model for HPV infection to the previously established athymic nude mouse model. HPV-11-infected foreskin fragments grafted under the renal capsule of SCID mice formed large epithelial cysts that had the histologic and immunocytochemical features of HPV infection. This infection was successfully passaged to nude mice. Viral particles that reacted to an antibody directed to HPV-11 virions were identified from samples recovered from the SCID and nude mice. Viral DNA sequence analysis confirmed that the passaged virus was HPV-11. In a comparative experiment of the nude mouse and SCID mouse models, the latter produced HPV-11-infected xenografts that were larger and more often positive for HPV by immunocytochemistry and presence of viral mRNA than those propagated in the former model. Finally, we observed that growth of HPV-11-infected foreskin fragments in the SCID mouse model is not restricted to the kidney as in the nude mouse, but also can occur in the subcutis and the peritoneum.

Biology of free radical scavengers: an evaluation of ascorbate

Reactive free radical species (R.) are associated with several forms of tissue damage and disease, and also with the process of aging. Protection is thought to be available in the form of endogenous compounds that react with and thereby "scavenge" the R.. Because many R. are reactive forms of oxygen, an effective scavenger is often referred to as an antioxidant. To be an effective antioxidant physiologically, a substance must have certain chemical and biological properties: it must be present in adequate amounts in the body; it must react with a variety of R.; it must be suitable for compartmentation; it must be readily available; it might be suitable for regeneration; it must be conserved by the kidneys; and it must have tolerable toxicity. Several water-soluble candidates are mentioned, with most having no more than one or two of the attributes listed. Ascorbic acid is discussed in detail, and an analysis is made of whether it has the properties mentioned.

Ascorbic acid regeneration by bovine iris-ciliary body

Ocular tissues appear to require high levels of ascorbic acid and the elucidation of the mechanisms by which those tissues maintain the vitamin in its reduced state remains an important objective. The regeneration of ascorbate from its oxidative by-product, dehydroascorbic acid (DHAA), was studied in bovine iris-ciliary body. Iris-ciliary body was removed by scalpel, weighed, minced, and homogenized in 20 mM MOPS, 62 mM sucrose, and 0.1 mM EDTA at pH 7.0. The homogenate was centrifuged and precipitated with ammonium sulfate such that maximal DHAA reducing activity was enhanced in a 50-75% ammonium sulfate fraction. This fraction was employed for subsequent characterization of DHAA reduction by iris-ciliary body. Results indicate that the iris-ciliary body enzymatically reduces DHAA to ascorbate at a rate significantly greater than can be accounted for by a nonenzymatic glutathione-dependent mechanism. In addition, saturation kinetics are observed, and the enzymatic activity is dependent on protein concentration, DHAA concentration, and reduced glutathione (GSH) concentration. The activity is sensitive to pH, to high temperature, and to digestion by trypsin and is greatest in the presence of both GSH and NADPH. The reducing activity is therefore attributed to one or more proteins that are distinct from the known ascorbate regenerating enzyme, GSH-dependent DHAA reductase (EC 1.8.5.1).

Evolution of the antibody response to human papillomavirus type 11 (HPV-11) in patients with condyloma acuminatum according to treatment response

To evaluate the variation over time of seroreactivity to human papillomavirus type 11 (HPV-11) according to disease outcome, we selected a sample of 42 condyloma acuminatum patients from a group of subjects enrolled in a placebo-controlled trial of three alpha-interferon preparations administered parenterally for the treatment of condyloma acuminatum. This sample included 14 subjects who were cured by the end of follow-up (cured group) and 28 subjects who were not (failed group). For each individual, the first and last sera collected in the study were tested with an intact HPV-11 virion-based enzyme linked immunosorbent assay (ELISA). The sera of 20 nuns with no lifetime sexual exposure served as controls. The median optical density (OD) value of the first serum samples (as well as that of the last samples) from the patients, 0.155, was higher than that of the control sera, 0.073 (P = 2 x 10(-4)). Sensitivity of the assay was 50%. To test if evolution of seroreactivity in the seropositive patients was related to disease outcome after treatment, we examined the average percentage of daily change in OD between the two serum collections. The median OD in the cured group (n = 7) dropped by 0.05% a day whereas in the failed group (n = 11) it increased by 0.07% a day, a highly statistically significant difference (P = 0.006). It is concluded that changes in the seroreactivity to HPV-11 virions are related to outcome of condyloma acumination after treatment. Therefore, improved serological assays may eventually contribute to the monitoring of HPV disease activity.

Expression of human papillomavirus type 11 L1 protein in insect cells: in vivo and in vitro assembly of viruslike particles

The L1 coat protein of human papillomavirus type 11 (HPV-11) was expressed in Sf-9 insect cells with the recombinant baculovirus vector Ac11L1. Viruslike particles (VLPs) were identified by electron microscopy in the nucleus and cytoplasm of Sf-9 cells infected with Ac11L1. The L1 protein was purified from Ac11L1-infected insect cells. The purified protein spontaneously assembled in vitro into various aggregates, including particles appearing similar to empty virions. Reaction of VLP-containing insect cell extracts with antisera directed against either denatured or nondenatured capsid epitopes in Western blot (immunoblot) and immuno-dot blot assays suggested that conformational epitopes present in native HPV-11 infectious virions were also present on the baculovirus-produced HPV-11 VLPs. Immuno-dot blot assays using human sera obtained from individuals with biopsy-proven condyloma acuminatum correlated closely with results previously obtained in HPV-11 whole virus particle-based enzyme-linked immunosorbent assays. These morphologic and immunologic similarities to native HPV-11 virions suggest that recombinant VLPs produced in the baculovirus system may be useful in seroepidemiology and pathogenesis studies of genital HPV infection and that they may also be potential candidates for vaccine development.

Lacrimal gland uptake and metabolism of ascorbic acid

Ascorbic acid is thought to contribute to protection against the potentially damaging effects of radiation, oxygen toxicity, and abrasion in the eye. The anterior surface of the cornea is particularly subject to insult from each threat. We considered the possibility that the lacrimal gland of pigs has transport and/or metabolic capability to sequester the reduced or oxidized form of ascorbic acid and prepare it for secretion in the tears. Slices of fresh lacrimal gland were incubated in a physiologic buffer and exposed to < or = 12 microM 14C-labeled ascorbic acid or dehydro-l-ascorbic acid over 40-min incubation periods. Dehydro-l-ascorbic acid was taken up to a greater extent than the reduced compound. 14C-Label recovered from the tissue was at least 75% in the form of ascorbic acid after incubation with either substrate. Uptake of both the reduced and oxidized substrates proceeded to a tissue to medium ratio in excess of unity; the former was prevented by the presence of nonlabeled ascorbate in the bathing medium, but was unaffected by the removal of Na+ from the bath. The uptake of both substrates was less after inhibition of cellular metabolic energy. The lacrimal gland in this diurnal animal species has transport and metabolic capabilities that could serve in secretion of ascorbic acid into tears. This might help to protect the corneal epithelium against various forms of damage.

Antibody response to human papillomavirus (HPV) type 11 in children with juvenile-onset recurrent respiratory papillomatosis (RRP)

We previously established, using an ELISA, the presence of specific antibodies directed at human papillomavirus (HPV) type 11 virions in the sera of patients with condylomata acuminata, mostly a disease of young adults that, like recurrent respiratory papillomatosis (RRP), is caused by two closely related HPVs, types 6 and 11. The present study was done to investigate if children with RRP can make viral-specific antibodies to an infection that is acquired at birth. Using the same ELISA, we studied the sera of 32 children with biopsy-documented juvenile-onset RRP and compared them to the sera of 31 control children. The median (and interquartile range) of the OD values in the controls and the cases was 0.078 (0.003, 0.101) and 0.230 (0.063, 0.725), respectively, a statistically significant difference (P = 0.001). Among the cases, there was no difference in seroreactivity between children with HPV-11-induced RRP and those with HPV-6-induced RRP (P = 0.31). Since HPV-11 viral particles do bind to the ELISA plate and remain intact and accessible to antibodies, we conclude that children with RRP, like adults with condylomata acuminata, develop antibodies directed at HPV-11 virions.

Antibody-mediated neutralization of human papillomavirus type 11 (HPV-11) infection in the nude mouse: detection of HPV-11 mRNAs

The nu/nu mouse xenograft is the only experimental system permitting the growth of human papillomaviruses (HPV). Previous studies demonstrating inhibition of HPV-11 infection by antibodies against HPV-11 virions have used indirect markers of infection, such as graft size and histopathologic features. The presence of HPV-11 mRNAs was used as a direct marker of infection: Infectious HPV-11 was incubated with rabbit serum raised against purified HPV-11 virions or with the corresponding preimmune serum (controls) before use in the mouse xenograft model, and HPV-11 mRNAs were detected by a method using reverse transcription and amplification by polymerase chain reaction. Graft size, histopathologic features, and the presence of capsid antigen were also assessed. Six weeks after infection, 1 of 23 grafts in the test group contained HPV-11 mRNAs compared with 19 of 20 controls (P less than .001). Therefore, antibody-mediated inhibition of infection by HPV-11 leads to blockade of genomic expression and is thus consistent with active prevention of viral penetration, that is, neutralization.

Short term effects of oxidized ascorbic acid on bovine corneal endothelium and human placenta

Studies on the toxic effects of dehydro-L-ascorbic acid (DHAA) have been extended to include evaluations over time periods up to 3 hr. and to test for specific effects on a membrane transport protein, a membrane-bound enzyme and a soluble intracellular enzyme. In studies on cultured corneal endothelial cells, DHAA concentrations of 1, 2, and 5 mM over 3 hr. had an inhibitory effect on subsequent uptake of DHAA present at a tracer level. Surviving fragments of human placenta and alkaline phosphatase activity of the placental brush-border membrane were susceptible to the effect of DHAA at a high concentration (10 mM). Because intracellular metabolism of DHAA was not affected, and an increase in membrane permeability was not detected, it is concluded that a specific membrane transport protein might be the site of DHAA-induced damage. These studies support the concept that the oxidized form of ascorbic acid (vitamin C) has potential toxic effects on biological systems and suggests that proteins that mediate transport and metabolism may be sites where DHAA causes damage.

Tissue-mediated regeneration of ascorbic acid: is the process enzymatic?

Ascorbic acid's function in animals is attributed in part to the ease with which it reduces potentially damaging components, such as reactive free radicals. After more than six decades of speculation and laboratory efforts, the mechanisms by which ascorbic acid is maintained in the useful, reduced state remain uncertain. Previous attempts to isolate the enzymes that reduce the partially and the fully oxidized metabolites of vitamin C are reviewed. Some speculation on why dehydroascorbate reductase (EC 1.8.5.1) has not been purified from animal tissues is presented.

Ascorbic acid uptake and metabolism by corneal endothelium

Ascorbic acid is concentrated in various ocular compartments where it is thought to protect diurnal animal species against damaging effects of ultraviolet radiation. The authors evaluated the possibility that corneal endothelial cells have specific transport and/or metabolic properties that deliver ascorbic acid to the stroma. Bovine corneal endothelial cells were grown to confluence in multiple-well plates. Individual groups of cells (approximately 10(4)) were then incubated at various times at 34 degrees C in a physiologic buffer that contained a 10 microM level of 14C-labeled ascorbic acid or the oxidized product, dehydro-L-ascorbic acid. Endothelial cells take up dehydro-L-ascorbic acid at least seven times as rapidly as they take up ascorbic acid. After 30 sec of incubation with 14C-dehydro-L-ascorbic acid, most of the label accumulated in the cell is in the reduced form. Uptake is inhibited by cyanide and iodoacetamide but is unaffected by ouabain. Exposure of cultured cells to various intermediates in the energy metabolism pathways reduced uptake of ascorbic acid but had a minor effect on uptake of the oxidized molecule. These results suggest that the cornea has transport and metabolic capacity to extract dehydro-L-ascorbic acid from aqueous humor and reduce it, thus providing a source of ascorbic acid for corneal protection. This also would maintain "total" ascorbic acid of aqueous humor in the reduced state.

Use of human papillomavirus type 11 virions in an ELISA to detect specific antibodies in humans with condylomata acuminata

Human papillomavirus types 6 and 11 (HPV-6 and HPV-11) are the major aetiological agents of condylomata acuminata. Serological studies of this disease have been difficult to perform and interpret because native, type-specific antigens have not been available. In particular, since these viruses have not been propagated in vitro and sufficient quantities of virions are not present in lesions, virus particles have been difficult to obtain. In the present study, we used HPV-11 particles, obtained from human tumours produced in athymic mice, as antigen in an ELISA to compare antibody responses between 46 patients with biopsyproven condylomata acuminata and 44 controls. The median [interquartile range] of the absorbance values for the condylomata acuminata and the control groups were respectively 0.324 [0.183, 1.029] and 0.118 [0.047, 0.286] (P = 0.0001). Thirty-three per cent of the absorbance values in the condylomata acuminata group were higher than any of those of the control group. Sera from patients whose biopsies contained the papillomavirus common antigen were more reactive than sera from patients whose biopsies did not contain it (P = 0.0014). This study demonstrates the presence of specific antibodies directed at native HPV-11 viral particles in the sera of patients with condylomata acuminata, and describes a test which can be used in future serological studies of this common sexually transmitted disease.

Detection of human papillomavirus types 6 and 11 E4 gene products in condylomata acuminatum

Polyclonal antiserum to an Escherichia coli-produced beta-galactosidase/E4 fusion protein of human papillomavirus type 6b (antiserum 256), and affinity purified HPV 11 anti-E4 antibodies were tested for reactivity in Western blots with bacterially expressed trpE/E4 fusion proteins of HPV types 6b, 11, 16, and 18. To further characterize the affinity purified anti-E4 antibodies, a dot-immunobinding assay was performed using overlapping synthetic HPV 11 E1E4 peptides as antigens. Protein extracts of condylomata acuminatum from 18 patients containing HPV type 6 or 11 DNA sequences were tested in Western blots using antiserum 256 or affinity purified HPV 11 anti-E4 antibodies. In the Western blots of the trpE proteins, antiserum 256 identified the HPV types 6b and 11 fusion proteins; the affinity purified HPV 11 anti-E4 antibodies identified only the HPV 11 fusion protein. In the dot-immunobinding assay, three HPV 11 peptides were recognized, each containing a shared 8 amino acid sequence that differs significantly from the corresponding sequences of HPV types 6b, 16, or 18. In the Western blots of protein extracts from 18 condylomata acuminatum samples shown to contain HPV types 6 or 11 DNA, putative E4 gene products were identified in six samples by antiserum 256. The affinity purified HPV 11 anti-E4 antibodies identified putative E4 gene products in one of these same six lesions, which was shown to contain HPV 11 sequences by the Southern blot method. All six samples containing E4 gene products were from women. Three of these women were pregnant, one had serum antibodies to the human immunodeficiency virus, and one was a renal transplant recipient receiving glucocorticoids.(ABSTRACT TRUNCATED AT 400 WORDS)