Biomedical subjects

S Shigeta

Publications and source records attributed to S Shigeta.

At least 91 records · Page 5Linked to original sources

PubMed1997

[Comparative studies on activities of antimicrobial agents against causative organisms isolated from patients with urinary tract infections (1995). III. Differences in susceptibilities from previous years].

Susceptibilities to various antimicrobial agents were examined for Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Klebsiella spp. and Pseudomonas aeruginosa that were isolated from patients with urinary tract infections (UTIs) in 11 hospitals during June, 1995 through May, 1996, and the results were compared with those obtained during the same period in earlier years. 1. Macrolide resistant E. faecalis isolated from uncomplicated UTIs during the latest study period appeared to have increased compared to those in previous study periods. More than 50% of the isolated E. faecalis during the latest study period were resistant to macrolide antibiotics, for the first time in our history. 2. No obvious changes were observed through the years for susceptibilities of S. aureus to various antimicrobial agents. Vancomycin (VCM) showed the highest activity against S. aureus, with MICs below 2 micrograms/ml or below. 3. Among E. coli strains, those with low susceptibilities to quinolones appeared to have increased over the years with MIC90 changed from between 0.125 microgram/ml or below and 0.5 microgram/ml in the 1989-1990 period to between 8 micrograms/ml and 128 micrograms/ml in the latest study period. 4. Klebsiella spp. showed higher resistance to most antimicrobial agents during periods of 1993-1994 and 1994-1995, but somewhat lower resistance during period of 1995-1996. No resistant Klebsiella spp. were detected from uncomplicated UTIs during the latest study period. 5. Among P. aeruginosa isolates from complicated UTIs, resistance isolates to gentamicin appeared to be increasing over the years. Resistant strains to quinolones were isolated at lower frequencies during periods of 1991-1994, but higher frequency was observed in the latest period, and MIC50s were between 0.5 and 4 micrograms/ml during 1991-1994, but were 16-32 micrograms/ml during 1995-1996. These susceptibility changes should be utilized in determining clinical treatments.

Anti-Bacterial Agents↗

PubMed1997

[Current status of research and development for anti-influenza virus drugs--chemotherapy for influenza].

Antiviral research for influenza viruses (FluV) is proceeding actively whereas few compounds are available for clinical use. Amantadine, an inhibitor of M2 ion-channel of FluV-A has been a key compound which disclosed important function of M2 protein, however, its clinical efficacy is restricted only in chemoprophylaxis of infection. Recently several compounds which showed novel antiviral mechanism for FluV replication emerged. They are inhibitors of conformation change of HA, of fusion of envelope and cellular membrane, of endonuclease on mRNA, of viral RNA replication, and of NA activity. Although most of these inhibitors are under investigations some of them are in clinical trial of phase II or phase III. It is obvious that most important problem in clinical use of anti-FluV drugs should be its side effects, bioavailability and stability in human bodies.

Amantadine↗

PubMed1997

[Comparative studies on activities of antimicrobial agents against causative organisms isolated from patients with urinary tract infections (1995). I. Susceptibility distribution].

The frequencies of isolation and susceptibilities to antimicrobial agents were investigated on 704 bacterial strains isolated from patients with urinary tract infections (UTIs) in 11 hospitals during the period of June 1995 to May 1996. Of the above bacterial isolates, Gram-positive bacteria accounted for 29.8% and a majority of them were Enterococcus faecalis. Gram-negative bacteria accounted for 70.2% and most of them were Escherichia coli. Susceptibilities of several isolated bacteria to antimicrobial agents were as followed; 1. Enterococcus faecalis Ampicillin (ABPC) and imipenem (IPM) showed the highest activities against E. faecalis isolated from patients with UTIs. The MIC90S of them were 1 microgram/ml. Vancomycin (VCM) and piperacillin (PIPC) were also active with the MIC90S of 2 micrograms/ml and 4 micrograms/ml, respectively. The others had low activities with the MIC90S of 16 micrograms/ml or above. 2. Staphylococcus aureus including MRSA VCM showed the highest activities against S. aureus isolated from patients with UTIs. Its MIC90 was 1 microgram/ml against both S. aureus and MRSA. Arbekacin (ABK) was also active with the MIC90 of 2 micrograms/ml. The other except minocycline (MINO) had very low activities with the MIC90S of 64 micrograms/ml or above. 3. Staphylococcus epidermidis ABK and MINO showed the strongest activities against S. epidermidis isolated from patients with UTIs. The MIC90S of them were 0.25 microgram/ml. VCM was also active with the MIC90 of 1 microgram/ml. The MIC90S of cephems ranged from 2 micrograms/ml to 16 micrograms/ml in 1994, but they ranged from 8 micrograms/ml to 128 micrograms/ml in 1995. These results indicated that some resistances existed among S. epidermidis to cephems. 4. Streptococcus agalactiae All drugs except gentamicin (GM) were active against S. agalactiae. ABPC, cefmenoxime (CMX), IPM, erythromycin (EM), clindamycin (CLDM) and clarithromycin (CAM) showed the highest activities. The MICs for all strains were lower than 0.125 microgram/ml. The MIC90S of the others were 2 micrograms/ml or below. 5. Citrobacter freundii IPM showed the highest activity against C. freundii isolated from patients UTIs. Its MIC90 was 1 microgram/ml. GM was also active with the MIC90 of 2 micrograms/ml. Cefpirome (CPR), cefozopran (CZOP) and amikacin (AMK) were also active with the MIC90S of 4 micrograms/ml. Penicillins and cephems except CMX, CPR and CZOP showed low activities with MIC90S of 256 micrograms/ml or above. 6. Enterobacter cloacae IPM showed the highest activity against E. cloacae. The MICs for all strains were equal to or lower than 1 microgram/ml. MINO and tosufloxacin (TFLX) were also active with the MIC90S of 8 micrograms/ml. Penicillins and cephems except CPR and CZOP showed lower activities with the MIC90S of 256 micrograms/ml or above. 7. Escherichia coli. Most of the antimicrobial agents were active against E. coli. Particularly CPR, CZOP and IPM showed the highest activities against E. coli. The MICs for all strains were equal to or lower than 0.5 microgram/ml. CMX and TFLX were also active with the MIC90S of 0.125 microgram/ml or below. Penicillins were slightly active with MIC90S of 128 micrograms/ml or above. 8. Klebsiella pneumoniae K. pneumoniae was susceptible to all drugs except penicillins, with MIC90S of 2 micrograms/ml or below. Carumonam (CRMN) had the strongest activity against K. pneumoniae, the MICs for all strains were equal to or lower than 0.125 microgram/ml. Comparing with the result of 1994, the sensitivities of K. pneumoniae against all drugs had obviously changed into a better state. For example, the MIC90S of cephems ranged from 0.25 microgram/ml to 16 micrograms/ml in 1994, but they were all lower than 2 micrograms/ml in 1995. 9. Proteus mirabilis P. mirabilis was susceptible to a majority of drugs. CMX, ceftazidime (CAZ), cefixime (CFIX), and CRMN showed the highest activities against P. mirabilis isolated from patients with UTIs. MICs of CRMN for all

Anti-Bacterial Agents↗

PubMed1997

[Comparative studies on activities of antimicrobial agents against causative organisms isolated from patients with urinary tract infections (1995). II. Background of patients].

Clinical background was investigated on patients with urinary tract infections (UTIs) from whom 785 bacterial strains were isolated in 11 hospitals during the period from June, 1995 through May, 1996. 1. Distributions of age and sex of patients and type of infections. Among the patients examined, those with ages 50 years or older were the most frequent (males: 80.5%, females: 69.7%), and, among females, those with ages in the 20's were 12.6%. With regard to types of infections, more than a half of infections among males were of complicated types, but most of infections among females were of uncomplicated types, especially among females of ages less than 60 years. 2. Ages of patients and types of pathogens. The higher the ages of patients, the lesser became the isolation frequencies of Proteus spp. and Serratia spp., but the higher were those of Klebsiella spp. and Pseudomonas spp. 3. Effect of antibiotic use on isolation frequencies of pathogens. Use of antibiotics decreased pathogens isolated from patients with uncomplicated UTIs drastically (237 isolates before antibiotics compared to 33 after). Even isolated pathogens from patients with complicated UTIs decreased drastically with the use of antibiotics when indwelling catheters were not in use (200 isolates before antibiotics compared to 83 after), but when indwelling catheters were in use, antibiotics apparently failed to decrease the isolation frequency. 4. Surgical procedures and types of causative organisms for UTIs. Escherichia coli was the most frequently isolated organism from uncomplicated cases of UTIs. From cases of complicated UTIs without indwelling catheters, Enterococcus faecalis was the most frequently isolated, followed by E. coli, P. aeruginosa and Klebsiella spp. When a surgical procedures were not done, E. coli was isolated most frequently. From cases of complicated UTIs with indwelling catheters, P. aeruginosa, E. faecalis and S. aureus were the organisms that were mainly isolated, with isolation frequencies of 23.9%, 17.3% and 12.7%, respectively. When no surgical procedures were used, isolation frequencies of P. aeruginosa, Klebsiella spp. and E. faecalis were 25.7%, 14.3% and 14.3%, respectively.

Adolescent↗

PubMed1996

Synthesis and antiviral activity of 5-substituted (2'S)-2'-deoxy-2'-C-methylcytidines and -uridines.

Synthesis of several 5-substituted (2'S)-2'-deoxy-2'-C-methylcytidines (8) and -uridines (6, 11) has been accomplished using radical deoxygenation of the 2'-tert-alcohols via their methyl oxalyl esters as a key reaction. Anti-herpes simplex virus type-1 and -2, and anti-varicella-zoster virus activities of the newly synthesized nucleosides were evaluated. Among them, the 5-iodouracil derivative 6e showed the most potent activity against herpes simplex virus type-1, with an EC50 of 0.14 micrograms/mL without showing cytotoxicity up to 100 micrograms/mL, but had a weak activity against herpes simplex virus type-2 and no activity against varicella-zoster virus up to 50 micrograms/mL in vitro. Although the 5-fluorocytosine derivative 8b had a potent anti-herpes simplex virus type-1 activity (EC50 = 0.22 micrograms/mL), it was rather cytotoxic to the CCRF-HSB-2 human T-cell line (IC50 > or = 1.0 microgram/mL).

Animals↗

PubMed1996

Heat shock induces HIV-1 replication in chronically infected promyelocyte cell line OM10.1.

A long period of clinical latency before development of symptoms is characteristic of human immunodeficiency virus type 1 (HIV-1) infection. OM10.1, a promyelocyte cell line latently infected with HIV-1, has been developed as a model for studying the mechanism of viral latency and the activation of virus expression. We found that this latently infected cell line with heat shock at 42 degrees C for 2 h resulted in a high level of HIV-1 production without addition of any cytokines. The mechanism of activation was analyzed by using anti-TNF-alpha antibody and various inhibitors. Although the TNF-alpha level in culture supernatants was below the sensitivity of an ELISA assay system, addition of anti-TNF-alpha antibody in culture medium could partially suppress the heat shock induced HIV-1 production. Staurosporine (PKC inhibitor), pentoxifylline (NF-kappa B inhibitor), and Ro5-3335 (HIV-1 Tat inhibitor) also inhibited significantly the heat shock induced virus activation. In particular, staurosporine achieved approximately 90% inhibition of the HIV-1 antigen expression in heat shock-treated OM10.1 at a non-toxic concentration. Although the mechanism of HIV-1 activation with heat shock has not been fully elucidated yet, it is presumed PKC plays an important role in HIV-1 activation. Thus, the present observations will provide a further insight into the pathogenesis of HIV-1 infections.

Alkaloids↗

PubMed1996

Cloning and characterization of a new allergen, Mag 3, from the house dust mite, Dermatophagoides farinae: cross-reactivity with high-molecular-weight allergen.

A new immunoreactive clone whose sequence is not homologous to that of any of the previously identified mite allergens was isolated by successive immunoscreening of a Dermatophagoides farinae cDNA library with rabbit antisera to an extract of the house dust mite and IgE in pooled sera from patients allergic to mites. Rabbit antibodies specific for the recombinant protein recognized a 177 kD protein in a mite body extract. This immunoreactive protein was located in the circumferential tissues of esophagus, gut and the other internal organs in mites. The reaction of human IgE to the purified natural antigen was inhibited competitively to 30% by the recombinant antigen. In terms of the frequency and the intensity of response to specific IgE in sera from asthmatic patients, the natural protein was similar to Der f2, while the recombinant protein was slightly less allergenic by these criteria. We conclude that the natural protein from the house dust mite, D. farinae, is an important allergen.

Amino Acid Sequence↗

PubMed1996

B cell mitogenic activity of house dust mite, Dermatophagoides farinae, antigens.

The effect of mite antigens on murine and human lymphocytes was studied in vitro. Antigens prepared from Dermatophagoides farinae feces and bodies stimulated normal murine spleen cells to proliferate in a dose-dependent manner. The responder cells are B cells, because the response was reduced by the treatment of spleen cells with anti-immunoglobulin antibody and complement, but not with anti-Thy 1 antibody and complement. Furthermore, nylon column-purified T cells did not respond. The stimulation of B cells with mite antigens was not due to the contamination of lipopolysaccharide, a representative B cell mitogen, because C3H/HeJ spleen cells which are low responders to lipopolysaccharide could respond to mite antigens. These antigens induced not only proliferative response of murine B cells, but also immunoglobulin production. By gel-filtration column chromatography, the active fractions were eluted around the molecular weight of 150-155 kDa. Furthermore, mite antigens also stimulated human B cells to proliferate and to produce immunoglobulin. All these results suggest that mite antigens are a potent B cell mitogen and this activity might concern the induction of allergic reaction.

Animals↗

PubMed1996

Establishment of an in vitro assay system for screening hepatitis C virus protease inhibitors using high performance liquid chromatography.

The hepatitis C virus (HCV) genome contains the code for a conserved, serine-type protease, called NS3, for the processing of the non-structural protein region of the viral polyproteins. Furthermore, a related protein, NS4A, is an effector or cofactor of NS3 protease activity in the cleavage of NS3-4A, NS4A-4B, NS4B-5A and NS5A-5B junctions. To establish an in vitro assay system for the screening of those enzyme inhibitors that inhibit the protease NS3-4A, we prepared a maltose-binding protein-NS3-NS4A fusion protein and a synthetic peptide substrate that mimics the NS5A-5B junction. Cleavage of the synthetic peptide was analyzed by reversed-phase high performance liquid chromatography (HPLC). We showed that the enzymatic activity of the NS3-NS4A fusion protein was enhanced in comparison to the NS3 protein alone. The assay conditions for optimum NS3-4A protease activity were determined to be pH 7.6 and 37 degrees C. In addition, we evaluated several protease inhibitors using the same HPLC assay system. The activity of HCV protease NS3-4A was inhibited by 2714.4 microM diisopropyl fluorophosphate, 270.8 microM N-tosyl-L-lysyl chloromethyl ketone, and 825.5 microM chymostatin. The results of the present study indicated that the synthetic peptide substrate and HPLC assay system are suitable for studying HCV protease activity and may facilitate the development of anti-HCV therapeutic reagents.

Amino Acid Sequence↗

PubMed1996

2-Glycineamide-5-chlorophenyl 2-pyrryl ketone, a non-benzodiazepin Tat antagonist, is effective against acute and chronic HIV-1 infections in vitro.

In the search for effective Tat-dependent transcription inhibitors using a screening assay system that has recently been developed, 2-glycineamide-5-chlorophenyl 2-pyrryl ketone (GCPK) has proved to be a potent and selective inhibitor of human immunodeficiency virus type 1 (HIV-1) replication in vitro. This compound was inhibitory to HIV-1 replication in both acutely and chronically infected cells. The 50% effective concentration (EC50) of GCPK in acutely infected MOLT-4 and CEM cells was 0.62 and 0.13 microgram/ml, respectively. These values were similar to those of the known Tat-dependent transcription inhibitors Ro5-3335 and Ro24-7429. Like these inhibitors, GCPK could inhibit HIV-1 replication in MOLT-4/IIIB (MOLT-4 cells chronically infected with HIV-1) and tumor necrosis factor-alpha-(TNF-alpha)-induced viral activation in OM10.1 cells (a HL-60 clone latently infected with HIV-1). GCPK is distinct from Ro5-3335 and Ro24-7429 in that this novel Tat-dependent transcription inhibitor has no benzodiazepin ring.

Anti-HIV Agents↗

PubMed1996

Antiviral activities of nucleotide heterodimers against human immunodeficiency virus type 1 in vitro.

Nucleotide heterodimers were synthesized and examined for their inhibitory effects on the replication of human immunodeficiency virus type 1 (HIV-1), including HIV-1 reverse transcriptase (RT) inhibitor-resistant mutants. 3'-Azido-3'-deoxythymidilyl-(5')-phospho-(5')-6-[(3', 5'-dimethylphenyl)thio]-5-ethyl-1-[(2-hydroxyethoxy)methyl]uracil (AZT-P-E-HEPU-dM) and 3'-azido-3'-deoxythymidilyl-(5')-phospho-(5')-2', 3'-dideoxyinosine (AZT-P-ddI) proved to be highly potent and selective inhibitors of HIV-1 (IIIB strain) in MT-4 cells. The mechanism of inhibition by these heterodimers may be attributed to their degradation and the formation of each constituent. AZT-P-E-HEPU-dM was also markedly inhibitory to an AZT-resistant mutant (HIV-1-IIIB/AZT) and an E-HEPU-dM-resistant mutant (HIV-1-IIIB-R). However, AZT-P-ddI was found to have a less inhibitory effect on HIV-1-IIIB/AZT than on HIV-1-IIIB. The heterodimers of (5',5') AZT and ribavirin (AZT-P-Ribavirin) and (5',5') ddI and ribavirin (ddI-P-Ribavirin) were also synthesized: AZT-P-Ribavirin inhibited HIV-1 replication, but ddI-P-Ribarvirin did not.

Anti-HIV Agents↗

PubMed1996

Anti-HIV-1 activity of thiadiazole derivatives: structure-activity relationship, reverse transcriptase inhibition, and lipophilicity.

The structure-activity relationship of the non-nucleoside HIV-1-specific reverse transcriptase (RT) inhibitors 4-phenyl-1,2,5-thiadiazol-3-yl N,N-dialkylcarbamate (TDA) derivatives was investigated with respect to their anti-HIV-1 activity, RT inhibition, and lipophilicity. 4-Phenyl-1,2,5-thiadiazol-3-yl N,N-dimethylcarbamate inhibited HIV-1-induced cytopathic effect (CPE) by 50% at a concentration of 28.8 microM in MT-4 cells. The activity increased more than 100-fold when the hydrogens at the 2-position and the 6-position in phenyl moiety were substituted by chlorines. However, the derivative with a chlorine at the 4-position of phenyl moiety did not show any inhibition of HIV-1 replication at its non-toxic concentrations. All of the 4-(2,6-dichlorophenyl)-1,2,5-thiadiazol-3-yl N-methyl-N-alkylcarbamates proved inhibitory to HIV-1 replication in the nanomolar concentration range. The TDA derivatives that showed anti-HIV-1 activity also inhibited RT activity in an enzymatic assay. However, the TDA derivatives did not show any specific inhibition of a non-nucleoside RT inhibitor (NNRTI)-resistant mutant and its RT activity. When the TDA derivatives were examined for their inhibitory effect on HIV-1 replication in the presence of 50% human serum, the activity significantly decreased depending on-their lipophilicity.

Anti-HIV Agents↗

PubMed1996

Application of a gastric cancer cell line (MKN-28) for anti-adenovirus screening using the MTT method.

We established a sensitive and accurate method for screening of anti-adenovirus agents using the 3-(4,5-dimetylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. MKN-28 cells, which are well-differentiated stomach adenocarcinoma cells, were used for adenovirus (ADV) infection and examined for the anti-ADV activities of several established anti-herpes virus agents. ADV-11 is the causative agent of respiratory and urinary infections. It frequently causes hemorrhagic cystitis in immunocompromised hosts. One laboratory strain and 4 clinical isolates of ADV-11 were examined, and found susceptible (in order of decreasing activity) to 2-amino-7-[(1,3-dihydroxy-2-propoxy)methyl]purine (S-2242), (S)-9-(3-hydroxy-2-phosphonylmethoxypropyl)adenine[(S)-HPMPA ], and (S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine[(S)-HPMPC++ +]. On the other hand, ganciclovir and iododeoxyuridine were only weakly effective and dextran sulfate was ineffective. Our findings indicate that the MTT assay using MKN-28 cells is applicable to anti-ADV screening. The anti-ADV activity of (S)-HPMPA and (S)-HPMPC was confirmed, and, furthermore, S-2242 emerged as a highly potent and selective inhibitor of ADV-11.

Adenine↗

PubMed1996

Inhibitory effect of 4-(2, 6-dichlorophenyl)-1, 2, 5-thiadiazol-3-yl-N-methyl, N-ethylcarbamate on replication of human immunodeficiency virus type 1 and the mechanism of action.

In the search for effective antiviral agents, we have found 4-(2, 6-dichlorophenyl)-1, 2, 5-thiadiazol-3-yl-N-methyl, N-ethylcarbamate (RD4-2025) to be a highly potent and selective inhibitor of human immunodeficiency virus type 1 (HIV-1) in vitro. The 50% effective concentration of RD4-2025 for HIV-1-induced cytopathic effect in MT-4 cells was 37 nM, yet no antiviral activity was observed against HIV-2. In HIV-1 reverse transcriptase (RT) assays, RD4-2025 inhibited both RNA-dependent and DNA-dependent DNA polymerase activities of a recombinant HIV-1 RT with 50% inhibitory concentrations of 0.11 and 3.5 microM, respectively. However, the compound did not affect the activity of human DNA polymerase alpha. Kinetic studies revealed that the inhibition was noncompetitive with respect to dGTP as the substrate and poly(C)/(dG) 12-18 as the template/primer. These results were in accordance with those of nonnucleoside RT inhibitors (NNRTIs), such as R89439 (an alpha-anilinophenylacetamide derivative) and nevirapine, indicating that RD4-2025 also belongs to the family of NNRTIs.

Carbamates↗

PubMed1996

Follicular dendritic cells in vitro are not susceptible to infection by HIV-1.

OBJECTIVES: To investigate whether follicular dendritic cells (FDC) are target cells for HIV-1 infection. DESIGN: Based on the principle that if FDC are true target cells, HIV-1 particles will bind to the surface of FDC and then invade their cytoplasm and nuclei. METHODS: Freshly isolated tonsilar FDC were exposed to two strains (HE and JR-FL) of HIV-1 and cultured. They were then examined for HIV-1 replication, using p24 antigen-capture enzyme-linked immunosorbent assay, immunolabelling, and polymerase chain reaction (PCR) amplification. We used FDC clusters as the FDC source, since the culture system for FDC clusters has various advantages over other methods for the successful long-term culture of FDC. RESULTS: After 2 h incubation, particles of both HIV-1 strains bound to the surfaces of FDC, as well as to CD4+ T cells, although FDC do not have CD4 receptors. The FDC gradually released the particles into the culture supernatant. More HIV-1 particles were bound to fresh FDC than to dedifferentiated FDC or to control fibroblasts. However, HIV-1 particles bound to the FDC did not seem to enter the cells. We found no evidence of HIV-1 proviral DNA synthesis in FDC. CONCLUSIONS: Our results suggest that FDC are not readily infected with HIV-1 in situ, although we found that FDC in vitro were not infected by HIV-1.

Cells, Cultured↗

PubMed1996

Different properties of wild type and drug-resistant mutants of human immunodeficiency virus type 1 reverse transcriptase in vitro.

Drug-resistant mutants of human immunodeficiency virus type 1 (HIV-1) emerge during treatment with various reverse transcriptase (RT) inhibitors in vitro and in vivo. However, the virological nature and pathogenic importance of these mutants have not been fully elucidated. In this study, we have examined HIV-1 mutants resistant to 3'-azido-3'-deoxythymidine (AZT) and nonnucleoside RT inhibitors (NNRTIs) for their infectivity, RT activity, and replication in MT-4 cells. Although the infectivity of AZT- and NNRTI-resistant mutants was similar, the RT activity of AZT-resistant mutants was much higher than that of NNRTI-resistant mutants and their wild types. Furthermore, the RT activity of NNRTI-resistant mutants was significantly lower than that of the wild types. In contrast, the replication of NNRTI-resistant mutants was found to be greater than that of AZT-resistant mutants and the wild types. When HIV-1 proviral DNA (cDNA) synthesis was examined by PCR in MT-4 cells infected with the wild type, AZT-resistant mutant, or NNRTI-resistant mutant, the PCR signal of the NNRTI-resistant mutant was found to be much higher than those of the wild type and AZT-resistant mutant. These results suggest that the drug-resistant mutants differ from their corresponding wild types not only in drug sensitivity but also in other virological properties.

Antiviral Agents↗

PubMed1996

Evaluation of antiherpetic compounds using a gastric cancer cell line: pronounced activity of BVDU against herpes simplex virus replication.

We developed a rapid and simple method for the screening of antiviral agents against herpes simplex virus (HSV) in a model of gastrointestinal herpetic infection in vitro. This method was based on inhibition of HSV-induced cytopathogenicity in gastric adenocarcinoma MKN-28 cells, as monitored by an MTT colorimetric assay. From the various compounds that were evaluated for their activity against HSV-1 and HSV-2, brivudine (BVDU) emerged as the most effective. When the 50% effective concentration (EC50) values of the antiherpes agents in MKN-28 cells were compared with those in human embryo lung MRC-5 cells, all compounds, except for BVDU, showed higher EC50 values in MKN-28 cells. For BVDU the EC50 values in MKN-28 cells were 0.8 (HSV-1) and 0.036 (HSV-2) times the EC50 values in MRC-5 cells. Thus BVDU was 27.5 times more active against HSV-2 in MKN-28 cells than in MRC-5 cells. The MKN-28 gastric cancer cells may be useful for the rapid screening of anti-HSV agents and, in particular, those that may be useful in therapy of gastrointestinal HSV infections in gastrointestinal herpetic infection.

Adenocarcinoma↗

PubMed1996

Colorimetric assay system for screening antiviral compounds against hepatitis B virus.

A highly sensitive, rapid, and accurate assay system was developed for the in vitro evaluation of anti-hepatitis B virus (anti-HBV) agents. Chronic HBV-producing HB611 cells were used in combination with immunoaffinity purification, polymerase chain reaction (PCR), and hybrid capture detection. HB611 cells were incubated with putative anti-HBV agents for 7 days in 96-well microtiter plates. HBV was purified from HB611 cell culture media using immunoaffinity purification. The HBV DNA was extracted, amplified with PCR, and assayed using a hybrid capture colorimetric method. This assay provided quantitative detection of extracellular HBV DNA from 25 microliters of cell culture media. Using the colorimetric method, we found that 50% effective concentration levels of several known anti-HBV agents (HPMPA, PMEDAP, PMEA and others) were similar to those reported in studies using Southern blot analysis. These results demonstrate that this new and easily automated colorimetric assay system can be used for the rapid and accurate assessment of anti-HBV compound selectivity.

Adenine↗