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E R Kern

Publications and source records attributed to E R Kern.

At least 37 records · Page 2Linked to original sources
PubMed1999

Antiviral activities of biflavonoids.

Biflavonoids such as amentoflavone (1), agathisflavone (2), robustaflavone (3), hinokiflavone (4), volkensiflavone (5), rhusflavanone (7), succedaneflavanone (9), all isolated from Rhus succedanea and Garcinia multiflora, as well as their methyl ethers and acetates, volkensiflavone hexamethyl ether (6), rhusflavanone hexaacetate (8), and succedaneflavanone hexaacetate (10) were evaluated for their antiviral activities. The inhibitory activities against a number of viruses including respiratory viruses (influenza A, influenza B, respiratory syncytial, parainfluenza type 3, adenovirus type 5, and measles) and herpes viruses (HSV-1, HSV-2, HCMV, and VZV) were investigated. The results indicated that robustaflavone exhibited strong inhibitory effects against influenza A and influenza B viruses with EC50 values of 2.0 micrograms/ml and 0.2 microgram/ml, respectively, and selectivity index values (SI) of 16 and 454, respectively. Amentoflavone and agathisflavone also demonstrated significant activity against influenza A and B viruses. Amentoflavone and robustaflavone exhibited moderate anti-HSV-1 anti-HSV-2 activities with EC50 values of 17.9 micrograms/ml (HSV-1) and 48.0 micrograms/ml (HSV-2) and SI values of > 5.6 (HSV-1) and > 2.1 (HSV-2) for amentoflavone; EC50 values of 8.6 micrograms/ml (HSV-1) and 8.5 micrograms/ml (HSV-2), and SI values of > 11.6 (HSV-1) and > 11.8 (HSV-2) for robustaflavone. Rhusflavanone demonstrated inhibitory activities against influenza B, measles, and HSV-2 viruses with SI values of 9.3, 8 and > 6.4, respectively. Succedaneaflavanone exhibited inhibitory activities against influenza B virus and VZV with SI values of 15 and < 3.0, respectively.

Antiviral Agents↗
PubMed1999

Herpes simplex virus type 2 infection induced apoptosis in peritoneal macrophages independent of Fas and tumor necrosis factor-receptor signaling.

Freshly isolated macrophages from mature mice are poorly or nonpermissive for infections with HSV. However, despite lack of significant viral replication, HSV infection has been demonstrated to induce substantial cell death among macrophages. To determine if HSV-induced cytotoxicity of macrophages is due to apoptosis, peritoneal macrophages were obtained from C57BL/6 (B6) mice, and apoptosis was analyzed following HSV-2 infection in vitro. Macrophages underwent apoptosis upon HSV-2 infection indicated by annexin V staining, labeling of DNA strand breaks and electronmicroscopy. Apoptosis was associated with macrophage activation demonstrated by upregulation of MHC class II and Mac-1 surface expression. Though there was also an upregulation of Fas (Apo-1/CD95) and tumor necrosis factor (TNF)-receptor 1 (TNF-R1) pathways, inhibition of Fas by soluble Fas and blocking of TNF-alpha using a TNF-binding protein did not prevent HSV-induced apoptosis. Moreover, apoptosis was not impaired in HSV-2 infected macrophages from Fas-deficient B6-lpr/lpr mice suggesting involvement of other apoptosis pathways, or activation of Fas or TNF-R pathways downstream of the receptor level. The present results demonstrate that HSV-2 infection leads to activation and subsequent apoptosis in peritoneal macrophages independent of Fas or TNF-R1 signaling.

Animals↗
PubMed1998

Apoptosis mediated by Fas but not tumor necrosis factor receptor 1 prevents chronic disease in mice infected with murine cytomegalovirus.

The role of Fas- and TNF-receptor 1 (TNF-R1)-mediated apoptosis in the clearance of virally infected cells and in the regulation of the immune response was analyzed after murine cytomegalovirus (MCMV) infection of C57BL/6 (B6)-+/+ mice, Fas-mutant B6-lpr/lpr mice, TNF-R1 knockout B6-tnfr0/0 mice, and double-deficient B6-tnfr0/0 lpr/lpr mice. There was approximately equivalent clearance of MCMV in B6-+/+, B6-tnfr0/0, and B6-lpr/lpr mice, and by day 28 no infectious virus could be detected in the liver, kidney, lung, or peritoneal exudate. However, delayed virus clearance was observed in B6-tnfr0/0 lpr/lpr mice. An acute inflammatory response occurred in the liver, lung, and kidney of all mice, which was most severe 7 d after MCMV infection, but resolved by day 28 in B6-+/+ and B6-tnfr0/0 mice, but not in B6-lpr/lpr or B6-tnfr0/0 lpr/lpr mice. These results indicate that apoptosis mediated by either Fas or TNF-R1 is sufficient for rapid clearance of the virus. However, apoptosis induced by Fas, but not TNF-R1, is required for the downmodulation of the immune response to the virus and prevention of a chronic inflammatory reaction.

Animals↗
PubMed1998

(Z)- and (E)-2-((hydroxymethyl)cyclopropylidene)methyladenine and -guanine. New nucleoside analogues with a broad-spectrum antiviral activity.

New nucleoside analogues 14-17 based on a methylenecyclopropane structure were synthesized and evaluated for antiviral activity. Reaction of 2,3-dibromopropene (19) with adenine (18) led to bromoalkene 20, which was benzoylated to give N6,N6-dibenzoyl derivative 23. Attempts to convert 20 or 23 to bromocyclopropanes 21 and 22 by reaction with ethyl diazoacetate catalyzed by Rh2(OAc)4 were futile. By contrast, 2,3-dibromopropene (19) afforded smoothly (E)- and (Z)-dibromocyclopropane carboxylic esters 24 + 25. Alkylation of adenine (18) with 24 + 25 gave (E)- and (Z)-bromo derivatives 21 + 22. Base-catalyzed elimination of HBr resulted in the formation of (Z)- and (E)-methylenecyclopropanecarboxylic esters 26 + 27. More convenient one-pot alkylation-elimination of adenine (18) or 2-amino-6-chloropurine (30) with 24 + 25 afforded (Z)- and (E)-methylenecyclopropane derivatives 26 + 27 and 31 + 32. The Z-isomers were always predominant in these mixtures (Z/E approximately 2/1). Reduction of 26 + 27 and 31 + 32 with DIBALH afforded (Z)- and (E)-methylenecyclopropane alcohols 14 + 16 and 33 + 34. The latter were resolved directly by chromatography. Compounds 14 + 16 were converted to N6-(dimethylamino)methylene derivatives 28 and 29 which were separated and deprotected to give 14 and 16. Reaction of 33 and 34 with HCO2H led to guanine analogues 15 and 17. The 1H NMR spectra of the Z-analogues 14 and 15 are consistent with an anti-like conformation of the nucleobases. By contrast, 1H NMR and IR spectra of bromo ester 21 are indicative of syn-conformation of adenine. Several Z-(hydroxymethyl)methylenecyclopropanes exhibited in vitro antiviral activity in micromolar or submicromolar range against human and murine cytomegalovirus (HCMV and MCMV), Epstein-Barr virus (EBV), human herpes virus 6 (HHV-6), varicella zoster virus (VZV), and hepatitis B virus (HBV). Analogues 14, 15, and 33 were the most effective agents against HCMV (IC50 1-2.1, 0.04-2.1, and 0.8-5.6 microM), MCMV (IC50 2.1, 0.3, and 0.3 microM) and EBV in H-1 (IC50 0.2, 0.3, and 0.7 microM) and Daudi cells (IC50 3.2, 5.6, and 1.2 microM). Adenine analogue 14 was active against HBV (IC50 2 microM), VZV (IC50 2.5 microM), and HHV-6 (IC50 14 microM). Synadenol (14) and the E-isomer (16) were substrates of moderate efficiency for adenosine deaminase from calf intestine. The E-isomer 16 was more reactive than Z-isomer 14. The deamination of 14 effectively stopped at 50% conversion. Synadenol (14) was also deaminated by AMP deaminase from aspergillus sp.

Adenosine↗
PubMed1998

Murine cytomegalovirus induces a Sjögren's syndrome-like disease in C57Bl/6-lpr/lpr mice.

OBJECTIVE: To analyze Fas and tumor necrosis factor receptor I (TNFRI) apoptosis pathways in salivary gland inflammatory disease induced by murine cytomegalovirus (MCMV) infection. METHODS: Four different strains of mice (C57BI/6 [B6]-+/+, Fas-deficient B6-lpr/lpr, TNFRI-deficient B6-tnfr1(0/0), and B6-tnfr1(0/0)-lpr/lpr mice) were infected intraperitoneally with the Smith strain of MCMV (1 x 10(5) plaque-forming units). Viral load was determined by a plaque assay, inflammation and apoptosis by immunohistochemistry and staining with terminal dUTP nickend labeling, and autoantibodies by enzyme-linked immunosorbent assay. RESULTS: Infectious MCMV was not detectable by day 100. Although all MCMV-infected mice developed acute sialadenitis by day 28, a chronic (>100 days), severe salivary gland inflammation and anti-Ro and anti-La antibodies developed only in the B6-lpr/lpr mice. Apoptotic cells were detected during the acute, but not the chronic, phase of inflammation. CONCLUSION: Both Fas- and TNFRI-mediated apoptosis contribute to the clearance of MCMV-infected cells in the salivary glands. However, because Fas-mediated apoptosis is necessary for the down-modulation of the immune response, a defect in this process can lead to a postinfection, chronic inflammatory response that resembles Sjögren's syndrome.

Animals↗
PubMed1998

Summary of the II International Symposium on Cytomegalovirus.

Human cytomegalovirus (HCMV) is a highly species-specific DNA virus belonging to the Betaherpesvirinae subfamily of the herpesviridae family. Like other herpesviruses, primary infection with HCMV is followed by persistence of the virus in a latent form. The sites of latency are still largely undefined, but they probably include bone marrow progenitor cells and peripheral blood monocytes. From these sites, the virus can reactivate, resulting in renewed shedding of the virus, or, in immunocompromized persons, development of disease. Humans are the only reservoir of HCMV and transmission occurs by person-to-person contact. Infection with HCMV is common. In most developed countries, HCMV seroprevalence steadily increases after infancy and 10-20% of children are infected before puberty. In adults, the prevalence of antibodies ranges from 40 to 100%. Although HCMV has a world-wide distribution, infection with HCMV is more common in the developing countries and in areas of low socioeconomic conditions, which is predominantly related to the closeness of contacts within these populations. Except for a mononucleosis-like illness in some persons, infection with HCMV rarely causes disease in immunocompetent individuals. However, HCMV can cause severe morbidity and mortality in congenitally infected newborns and immunocompromized patients, most notably transplant-recipients and HIV-infected persons. This article provides a review of the information presented at the Second International Symposium on Cytomegalovirus organized and convened by The Macrae Group (New York City, NY) in Acapulco, Mexico on 24-28 April 1998. During this symposium, the state-of-the-art knowledge on diagnosis, treatment and prophylaxis of HCMV infections were discussed, and, based on this information, attempts to highlight the future directions in basic and clinical research areas that need to be stimulated to facilitate advancement in prevention and treatment of CMV disease.

AIDS-Related Opportunistic Infections↗
PubMed1998

Assessment of correlation between skin target site free drug concentration and the in vivo topical antiviral efficacy in hairless mice for (E)-5-(2-bromovinyl)-2'-deoxyuridine and acyclovir formulations.

Recently, we reported that the in vivo efficacy of acyclovir (ACV) formulations was a single valued function of skin target site free drug concentration (C) irrespective of the formulation compositions. A long-term objective of this research has been to generalize the C concept using model drugs which are similar to as well as different from ACV in their mechanism of actions. (Bromovinyl)deoxyuridine (BVDU) was selected as a model drug based on the reported similarity in its mechanism of action with ACV. The relationship between the C predictions and the in vivo efficacies for some topical formulations containing different concentrations (0.05-10%) of either ACV or BVDU in 95% DMSO as a vehicle with or without 5% Azone as skin permeation enhancer was examined. Hairless mice infected cutaneously with HSV-1 were used to quantitatively estimate the in vivo topical antiviral efficacy. A finite dose of the test antiviral formulation was applied twice a day for 4 days, starting the day after virus inoculation. On the fifth day, the lesions were scored and the efficacy values were calculated. For each formulation, in vitro flux experiments were performed in an in vivo-in vitro experimental design that closely approximated the in vivo study protocol. As was previously shown, with all ACV formulations, a good correlation was found between the C predictions and the in vivo topical efficacy. With the BVDU formulations, on the other hand, this was found not to be the case. BVDU formulations with 5% Azone were generally much more effective than those without Azone at comparable C values. This finding is believed to be the first of its kind showing that skin "permeation enhancers" may enhance efficacy by more than simply increasing skin permeation rates.

Acyclovir↗
PubMed1998

Chronic vulvar ulceration in an immunocompetent woman due to acyclovir-resistant, thymidine kinase-deficient herpes simplex virus.

A 34-year-old healthy woman presented with a 15-month history of persistent, nonhealing vulvar ulcerations due to herpes simplex virus (HSV) type 2. Extensive dermatologic workup and serial skin biopsies failed to reveal an underlying vulvar dermatosis or autoimmune bullous disorder. Virologic studies revealed resistance to acyclovir in vitro due to deficiency in thymidine kinase activity. Serum antibody to human immunodeficiency virus was negative on two occasions, separated by 1 year. Immunologic evaluation showed normal HSV-specific proliferative and CD8 cytotoxic T lymphocyte responses as well as normal NK cell function. Vulvar lesions failed to heal in association with trials of topical trifluorothymidine and oral valacyclovir but resolved completely with the application of 1% foscarnet cream. No recurrence of HSV has been observed in 24 months of follow-up to date.

Acyclovir↗
PubMed1998

Evaluation of a live attenuated recombinant virus RAV 9395 as a herpes simplex virus type 2 vaccine in guinea pigs.

Recombinant virus RAV 9395 was constructed by deleting both copies of the gamma(1)34.5 gene, and the UL55 and UL56 open reading frames from herpes simplex virus type 2 (HSV-2) strain G. The potential use of RAV 9395 as an HSV-2 vaccine was investigated by evaluating the ability of RAV 9395 to protect guinea pigs from severe disease by HSV-2(G) challenge. RAV 9395 administered intramuscularly reduced both lesion development and severity in a dose-dependent manner in guinea pigs challenged with HSV-2(G). The frequency of reactivation of RAV 9395 from explanted dorsal root ganglia was low compared with that of HSV-2(G). Immunization with RAV 9395 at doses of 1 x 10(5) pfu and above generally precluded the establishment of latency by the challenge virus. The results presented in this report lend support for the development of genetically engineered live HSV vaccines.

Animals↗
PubMed1998

(Z)- and (E)-2-(hydroxymethylcyclopropylidene)-methylpurines and pyrimidines as antiviral agents.

Several Z- and E-methylenecyclopropane nucleoside analogues were synthesized and tested for antiviral activity in vitro against human and murine cytomegalovirus (HCMV, MCMV), Epstein-Barr virus (EBV), varicella zoster virus (VZV), hepatitis B virus (HBV), herpes simplex virus types 1 and 2 (HSV-1, HSV-2), human herpesvirus 6 (HHV-6) and human immunodeficiency virus type 1 (HIV-1). The Z-2-amino-6-cyclopropylaminopurine analogue was the most effective agent against HCMV (EC50 or EC90 0.4-2 microM) followed by syncytol and the Z-2,6-diaminopurine analogues (EC50 or EC90 3.4-29 and 11-24 microM, respectively). The latter compound was also a strong inhibitor of MCMV (EC50 0.6 microM). Syncytol was the most potent against EBV (EC50 < 0.41 and 2.5 microM) followed by the Z-2,6-diaminopurine (EC50 1.5 and 6.9 microM) and the Z-2-amino-6-cyclopropyl-aminopurine derivative (EC50 11.8 microM). Syncytol was also most effective against VZV (EC50 3.6 microM). Activity against HSV-1, HSV-2 and HHV-6 was generally lower; synthymol had an EC50 of 2 microM against HSV-1 (ELISA) and 1.3 microM against EBV in Daudi cells but was inactive in other assays. The 2-amino-6-cyclopropylamino analogue displayed EC50 values between 215 and > 74 microM in HSV-1 and HSV-2 assays. 2-Amino-6-cyclopropylaminopurine and 2,6-diaminopurine derivatives were effective against HBV (EC50 2 and 10 microM, respectively), whereas none of the analogues inhibited HIV-1 at a higher virus load. Syncytol and the E isomer were equipotent against EBV in Daudi cells but the E isomer was much less effective in DNA hybridization assays. The E-2,6-diaminopurine analogue and E isomer of synthymol were devoid of antiviral activity.

Animals↗
PubMed1997

The synthesis and immunogenicity of varicella-zoster virus glycoprotein E and immediate-early protein (IE62) expressed in recombinant herpes simplex virus-1.

In order to evaluate the conditions for optimal expression and immunogenicity of varicella-zoster virus (VZV) proteins in a herpes simplex virus-1 (HSV-1) vector, we selected the VZV glycoprotein E (gE), encoded by ORF 68 and the VZV product of ORF 62, an immediate-early major tegument protein (IE62). Three HSV/VZV recombinants were generated: (1) VZV gE protein coding sequences along with the promoter region were inserted into the thymidine kinase (TK) gene of HSV-1 strain KOS; (2) VZV gE expressed from the HSV-1 ICP4 promoter was inserted into the glycoprotein C (gC) gene of HSV-1 strain F; and (3) VZV IE62 protein coding sequences under the control of the HSV-1 ICP4 promoter were inserted into the gC gene of HSV-1 strain F. Immunoblot analysis and immunoperoxidase staining of infected cell monolayers demonstrated vector expression of VZV proteins. Following intracranial inoculation in mice, both VZV gE-HSV (TK) and VZV IE62-HSV (gC) induced an IgG response against VZV gE or VZV IE62. When tested in cytotoxicity assays using T-lymphocytes from VZV immune human donors, the range of precursor frequencies for T-lymphocytes that recognized VZV gE or VZV IE62 was similar whether these proteins were expressed by HSV-1 or a vaccinia vector. These experiments demonstrate that HSV-1 is a competent vector for expression of these VZV proteins and support the feasibility of engineering a combined vaccine for these closely related alpha-herpesviruses.

Acyclovir↗
PubMed1997

Relationship of skin target site free drug concentration (C*) to the in vivo efficacy: an extensive evaluation of the predictive value of the C* concept using acyclovir as a model drug.

For the past few years, our laboratory has been involved in the development of a novel approach for predicting topical in vivo efficacy based on the estimation of skin target site free drug concentration (C*) from in vitro flux data. We have used acyclovir (ACV) as a model drug in the treatment of cutaneous herpes simplex virus type 1 infections in hairless mice. The goal of this study was to rigorously evaluate the applicability of this approach over the entire range of topical efficacy (i.e., from 0 to 100%). We employed a variety of ACV formulations differing in solvent compositions, enhancers, and excipients (and therefore in their efficacies) to achieve this goal. The C* values were estimated from the in vitro flux data obtained in an in vivo-in vitro experimental design that closely approximated the in vivo treatment protocol. For the in vivo antiviral efficacy studies, a finite dose of ACV formulation was applied twice a day, beginning the day after virus inoculation, for 4 days. The lesions were scored on the fifth day, and the efficacies were calculated as described earlier. Our results indicate that, for a variety of formulations over a wide range of efficacies, the predictions based on C* are in good agreement with the observed in vivo efficacies. These findings strongly demonstrate the predictive value of C* over the entire range of topical efficacy, thereby further strengthening its potential for future studies. The findings also indicate that although the excipients in a formulation may alter the rate and extent of available drug at the target site, in these cases, they do not seem to have any effect on the in vivo potency of the drug.

Acyclovir↗
PubMed1996

Role of animal models in selecting antiviral combinations for clinical studies.

Although experimental viral infections in animals have been used extensively in the development of antiviral drugs used as monotherapy, they have not been utilized widely for evaluation of combination chemotherapy. One of the major reasons for the lack of use of animal models is that for the diseases that are the main target for combination therapy, AIDS and hepatitis B and C infections, there is a lack of suitable models for these diseases. In contrast, most combination studies in animal models have been directed against herpes simplex virus infections but there are relatively few patients available who would benefit from combination therapy over single agent therapy. In between those two extremes are the cytomegalovirus infections. While there are animal models available that have been predictive of efficacy in humans and there are sufficient patients available, the use of antiviral combinations in animal models and in humans have begun only recently. At the present time there is not enough information available to establish the predictability for any of the animal models for efficacy of combinations of antiviral agents.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Differential effect of recombinant human and mouse interferons on replication of herpes simplex virus type 1 in mouse cells.

Pretreatment of murine (BALB/3T3) cells with either murine or recombinant hybrid human B/D interferon (IFN) blocked the release of infectious herpes simplex virus type 1 (HSV-1) from treated cells. The block in replication was not due to an effect on attachment of HSV-1 to the target cells or to toxic effects of IFN. Immunoblot analyses showed that murine IFN significantly reduced the expression of virus-specific proteins in IFN-treated cells. In contrast, B/D IFN had no major effect on the expression of viral proteins in treated cells. In support of the above observation, electron microscopy of virus-infected cells displayed formation of nucleocapsids within the nucleus of IFN-treated cells. However, the expression of glycoproteins B and D was reduced in B/D IFN-treated cells. These results suggested that murine IFN blocked HSV-1 replication at an early stage whereas B/D IFN inhibited HSV-1 replication at a late stage in virus morphogenesis.

3T3 Cells↗
PubMed1996

Correlation of in vivo topical efficacies with in vitro predictions using acyclovir formulations in the treatment of cutaneous HSV-1 infections in hairless mice: an evaluation of the predictive value of the C* concept.

The purpose of this study was to carry out an extensive examination of the C* concept for prediction of the topical antiviral efficacies of acyclovir (ACV) formulations in a hairless mouse model for the treatment of cutaneous herpes simplex virus type-1 (HSV-1) infections. This method is based on estimation of the free drug concentration at the target site (C*), which is presumed to be the basal cell layer of the epidermis. Five different formulations (containing 5% ACV) were examined in a finite dose multiple dosing regimen (twice a day application) to simulate the clinical situation. For determination of C*, in vitro ACV fluxes across the hairless mouse skin were measured in an in vivo-in vitro experimental design that approximated the in vivo antiviral treatment protocol. Then, the in vivo antiviral efficacies were measured using a 1-day delayed (after HSV-1 virus inoculation) 4-day treatment protocol. 10 microL/cm2 dose of ACV formulation was applied every 12 h for 4 days after which the lesions were scored and efficacies were calculated. Our results indicate that, over a wide range of efficacies, the predictions based on C* (estimated from the experimental fluxes) are in good agreement with the in vivo antiviral efficacies. These studies, therefore, support the validity of the C* concept for various ACV formulations and suggest that the C* approach has potential for future practical situations.

Acyclovir↗
PubMed1995

Synthesis and antiproliferative and antiviral activity of 2'-deoxy-2'-fluoroarabinofuranosyl analogs of the nucleoside antibiotics toyocamycin and sangivamycin.

The glycosylation of 3,4-dicyano-2-[(ethoxymethylene)amino]pyrrole (7) with 2-deoxy-2-fluoro-alpha-D-erythro-pentofuranosyl bromide (2) furnished an anomeric mixture of nucleosides (8a,b). This mixture was separated, and the individual anomers were treated with methanolic ammonia to effect a concomitant deblocking and ring closure. This furnished both anomers of 2'-deoxy-2'-fluoro-ara-toyocamycin (9a,b). The cyano moiety of 9b was converted to the carboxamide moiety to furnish 2'-deoxy-2'-fluoro-ara-sangivamycin (10) and to the thiocarboxamide moiety to furnish 2'-deoxy-2'-fluoro-ara-thiosangivamycin (11). The target compounds 10 and 11 showed similar antiproliferative activity against L1210 cells in vitro, with IC50's of 3 and 5 microM. Antiviral evaluation revealed a somewhat different pattern of activity. All analogs, both alpha and beta anomers, were active against human cytomegalovirus (HCMV), albeit the beta anomers were most active. The beta anomers also were active against herpes simplex virus type 1 (HSV-1) and human immunodeficiency virus (HIV). Compound 10 was most active in the series, ca. 10-fold more potent than 11; IC50's for 10 ranged from 4 to 25 nM for HCMV, HIV, and varicella zoster virus (VZV) and from 30 to 500 nM for HSV-1. Even though compound 10 was cytotoxic, which will probably preclude its use as an antiviral drug (IC50's = 0.2-5.5 microM), the difference between cytotoxicity and activity against HCMV, HIV, and VZV was sufficient to indicate specific activity against a viral target.

Antibiotics, Antineoplastic↗