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Biomedical subjects

J Harmenberg

Publications and source records attributed to J Harmenberg.

42 records · Page 3Linked to original sources

Intracellular pools of thymidine reduce the antiviral action of acyclovir.

Acyclovir inhibits herpes simplex virus (HSV) infections better in human fibroblasts than in green monkey kidney cells. Thymidine and acyclovir compete for the active site of HSV thymidine kinase. Large intracellular pools of thymidine found by high-performance liquid chromatography (HPLC) seemed to be responsible for the reduced activity of acyclovir. Such intracellular thymidine pools could not be measured previously, and the HPLC technique may help in evaluating the expected efficiency of acyclovir in cells and tissues prior to treatment.

Acyclovir↗

Influence of cell culture conditions on the inhibition of herpes simplex virus type 1 replication by acyclovir.

Inhibition of herpes simplex virus type 1 (HSV-1) replication, as measured by plaque reduction by acyclovir (ACV), was studied with different cell cultures and under varying conditions. Human lung fibroblasts (HL) required much lower concentrations of ACV for inhibition of virus replication than green monkey kidney (GMK) cells. In both cell types, ACV had to be added within 7 h after infection to cause a full antiviral effect. Pretreatment of cells with ACV before infection did not increase the antiviral activity. ACV caused a stronger inhibition in HL cells which had been confluent for 4 or 7 days as compared with cells just reaching confluence. Addition of ACV and its subsequent removal caused an irreversible plaque reduction in our experiments. ACV gave a pronounced inhibition of thymidine kinase (TK)-positive HSV-1 strains. A relatively small inhibitory effect was seen with a TK-negative HSV-1 strain in HL cells, and no measurable inhibition was seen in GMK cells. Inhibition of HSV-1 replication by ACV was concluded to depend on the type of virus, the cell type used, and the condition of the cells.

Acyclovir↗

Influence of cells and virus multiplicity on the inhibition of herpesviruses with acycloguanosine.

The inhibition of herpes simplex virus type 1 (HSV-1) plaque formation by acycloguanosine (ACG) was assayed in human fetal lung fibroblasts (HL), cell lines from human cervical carcinoma, rabbit cornea, and human rhabdomyosarcoma, and three green monkey kidney cell lines. The ACG concentration giving 50% plaque reduction (PR50) of HSV-1 was lowest in HL. In two green monkey kidney cell lines, HSV-1 plaque formation was relatively insensitive to ACG, with PR50 of 25 and 60 muM, respectively. In the other cells, HSV-1 showed an intermediate sensitivity to ACG. Also, HSV-2 was more sensitive to ACG in HL than in monkey kidney cells. HSV-1 plaque reduction on HL cells was studied as a function of increasing virus MOI with a constant concentration of ACG. An increased MOI decreased the sensitivity to ACG. The sensitivity of cytomegalovirus (CMV), strain Ad. 169, and four fresh CMV isolates to ACG was studied in HL cells. At low MOIs, three of the five CMV strains were somewhat sensitive to ACG, PR50 values ranging from 60 to 450 muM ACG. At high MOIs none of the virus strains were sensitive. ACG at concentrations of 200 muM or less did not significantly affect host cell DNA synthesis, as measured by 3H-thymidine incorporation. In cell culture, the inhibition of herpesviruses by ACG appears to be complex, depending on the type of virus, virus concentration, type of host cells, and condition of the cells.

Acyclovir↗

Possible tumour markers in patients with oesophagus cancer.

Carcinoembryonic antigen (CEA), alpha-foetoprotein (AFP), and enzymes were determined in the blood of 59 patients with primary oesophagus carcinoma. Raised CEA values were encountered in 59% of the patients, and AFP above that of an age-matched control group in 33% of the patients. Values of CEA during progression were significantly higher than in regression of disease. Two patients had exceptionally high serum AFP, but in most cases AFP levels were not related to disease progress. CEA and AFP could appear in a discordant fashion. The combined assay did not improve diagnostic sensitivity.

Adenocarcinoma↗

The mechanism of action of the anti-herpes virus compound 2,3-dimethyl-6(2-dimethylaminoethyl)-6H-indolo-(2,3-b)quinoxaline.

The compound 2,3-dimethyl-6(2-dimethylaminoethyl)6H-indolo-(2,3-b)quinoxaline (B-220) has been shown to exhibit potent antiviral activity against herpes simplex virus type 1 (HSV-1), varicella-zoster virus (VZV) and cytomegalovirus (CMV). The mechanism of antiviral action of B-220 against HSV-1 has been studied; from the results it appears that B-220 binds by intercalation into the DNA helix and then disturbs steps that are vital for viral uncoating.

Adsorption↗