Biomedical subjects

J B Hudson

Publications and source records attributed to J B Hudson.

At least 37 records · Page 2Linked to original sources

PubMed1993

The anti-HIV activity of the phytochemical alpha-terthienyl.

The plant trithiophene, alpha-terthienyl (alpha T), was evaluated for activity against the human immunodeficiency virus (HIV-1). Antiviral activity specifically required long wavelength light (UVA, 320-400 nm). The compound had little or no activity in visible light or in the dark. The anti-HIV effect was UVA-dose dependent and was proportional to the concentration of alpha T, according to several parameters of virus infectivity and replication. The efficacy was decreased to some extent by the presence of bovine serum in the reactions; but under optimal conditions 0.1 microgram/ml. alpha T (3 x 10(-7) M) could inactivate 10(4)-10(5) infectious particles. In contrast poliovirus and Coxsackievirus infectivity were relatively resistant to alpha T + UVA.

Blood↗

PubMed1993

DNA cleavage, antiviral and cytotoxic reactions photosensitized by simple enediyne compounds.

Very potent antibiotic antitumor natural products contain a enediyne moiety which, upon thermal activation, is capable of abstracting hydrogens from DNA. 1,6-Diphenyl-3-hexene-1,5-diyne was selected as a candidate for inducing DNA strand breaks photochemically. Easily interconverted with light, both geometric isomers 1 and 2 were expected to be phototoxic. As anticipated, they photosensitized the production of strand breaks in double-stranded supercoiled pBR322, and in single-stranded M13 DNA. The DNA cleavage reactions were favored by the presence of oxygen and were inhibited by ethanol. Preliminary experiments with the (Z)-isomer indicated moderate light-dependent antiviral activity against human immunodeficiency virus (HIV), Sindbis virus, and mouse cytomegalovirus. The enediynes were cytotoxic to Escherichia coli, a gram-negative organism, to Streptococcus faecalis, a gram-positive organism, to Daphnia magna and to fish (Pimephales promelas), but only in the presence of light. The production of o-terphenyl, the expected product of Bergman cyclization of 1, could not be confirmed. However, both 1 and 2 photosensitized the formation of singlet oxygen and of superoxide anion radical, and photodynamic reactions could have been responsible for some of the phototoxic reactions observed.

3T3 Cells↗

PubMed1993

Biological activities of terthiophenes and polyynes from the Asteraceae.

We evaluated a number of terthiophenes and polyynes, from the Asteraceae, for biological activities against microorganisms, viruses, and tumor cells, with and without the aid of UVA (long wavelength ultraviolet) radiation. The terthiophenes, which represented the basic alpha-terthienyl nucleus with simple side chains, showed impressive UVA-dependent activities, some of which were superior to alpha-terthienyl itself. In contrast, the polyynes had no significant biological activity, with or without UVA. We believe that these terthiophenes would be worthwhile evaluating in animal models of infectious diseases.

Alkynes↗

PubMed1993

The unusual UVA-dependent antiviral properties of the furoisocoumarin, coriandrin.

The novel furoisocoumarin, coriandrin, which was found recently to possess an interesting combination of photobiological properties, was investigated for antiviral activity in the presence and absence of UVA (long-wavelength ultraviolet radiation). In contrast to results obtained with other antiviral furocoumarins, such as 8-MOP (8-methoxypsoralen), coriandrin was much more phototoxic to the RNA-virus Sindbis virus than to the DNA-virus murine cytomegalovirus, although both viruses were substantially more sensitive to this compound than they were to 8-MOP. Human immunodeficiency virus, HIV-1, was also susceptible to coriandrin + UVA. Another unexpected finding was that viruses without membranes were completely resistant to coriandrin. This suggests that a membrane component was a target for the compound. The antiviral activity of coriadrin was profoundly inhibited by serum components in the reaction mixtures, which suggests that the compound may have a strong affinity for certain protein or lipid materials, although maximal interference was only obtained when all components of the reaction mixture, virus, coriandrin and serum, were irradiated simultaneously. Thus it appears that coriandrin has unusual antiviral properties that would not be predicted from its chemical similarity to furocoumarins.

3T3 Cells↗

PubMed1993

Light-mediated activities of thiarubrines against human immunodeficiency virus.

Two thiarubrines (dithiacyclohexadienes), which were isolated recently from species of Asteraceae, were investigated for light-mediated antiviral activity against human immunodeficiency virus (HIV-1). Both compounds (thiarubrines A and D) showed good anti-HIV activity, in micromolar concentrations, which was dependent upon UVA radiation. They showed no anti-viral activity in the dark, and only weak visible light-mediated activity, despite the significant absorbance of these compounds in the 480 nm region. The resulting inactivated virus was unable to replicate in cell cultures, as indicated by loss of cytopathogenicity, the absence of cells expressing HIV-1 antigens and lack of production of HIV-1 p24 protein. Although this antiviral activity was not as efficient as that shown by the photoactive plant thiophene, alpha-terthienyl, both thiarubrines demonstrated increased activity when the serum component of the virus stock was reduced. This suggested that a component of bovine serum interfered to some extent with the anti-HIV activity.

Alkynes↗

PubMed1993

The anti-HIV activities of photoactive terthiophenes.

Various synthetic analogues of the naturally occurring terthiophene, alpha-terthienyl (alpha T), were evaluated for anti-human immunodeficiency virus (HIV) activity. The compounds were incubated individually with a known amount of the virus, with or without UVA radiation (long-wavelength ultraviolet) and residual virus was monitored for its ability to produce cytopathic effects in cell culture and the production of virus-specific protein (p24). The basic terthiophene structure was essential for good anti-HIV activity, although various side chains, such as alcohols, bromo, methyl, thiomethyl and trimethylsilyl groups, permitted retention of maximum activity. Under optimum conditions, as little as 12 ng/mL of these compounds (i.e. approximately 3 x 10(-8) M) could inactivate 10(3) infectious virions. None of the compounds however were more active than alpha T itself. In all cases, UVA radiation was essential. Several side chains decreased the antiviral efficacy, and some side chains abrogated the activity.

Antiviral Agents↗

PubMed1992

Biosynthesis of human papillomavirus from a continuous cell line upon epithelial differentiation.

The study of the human pathogen papillomaviruses (HPVs) has been hampered by the inability to propagate the virus in tissue culture. The addition of 12-O-tetradecanoyl phorbol-13-acetate to the media of organotypic (raft) cultures increased expression of physiological markers of keratinocyte differentiation and concomitantly induced production of virions. Capsid production was detected in differentiated suprabasal cells. Virions approximately 54 nanometers in size were observed by electron microscopy in raft tissue cross sections in the suprabasal layers. Virions purified through isopycnic gradients were found to contain type 31b DNA and exhibited an icosahedral shape similar to that of papillomaviruses found in clinical samples.

Capsid↗

PubMed1992

Structure-activity studies of photoactivated antiviral and cytotoxic tricyclic thiophenes.

The photoactivated antiviral and cytotoxic activities of the naturally occurring thiophene, alpha-terthienyl (1), and 15 synthetic analogues were evaluated against murine cytomegalovirus and Sindbis virus, and murine mastocytoma cells. After irradiation with near UV light, alpha-terthienyl and most of its analogues had significant toxicity, with minimum inhibitory concentrations in the range of 0.02-40 microM. In the absence of near UV irradiation, only one analogue had antiviral activity and five were cytotoxic. The most active analogues were those containing carboxylic acid, hydroxyl, or cyano substituents. Quantitative structure-activity relationship analysis of thiophene phototoxicity suggested that the rate of singlet oxygen production is the primary determinant of antiviral and cytotoxic activities. For phototoxicity against murine cytomegalovirus, a significant role for hydrophobicity was also demonstrated. Tricyclic thiophenes show significant potential for photochemotherapy of viral infections and cancer, and further evaluation in animal models is recommended.

3T3 Cells↗

PubMed1992

Differentiation-induced and constitutive transcription of human papillomavirus type 31b in cell lines containing viral episomes.

The expression of viral genes during the productive life cycle of human papillomaviruses (HPV) is tightly coupled to the differentiation program of epithelial cells. We have examined transcription of HPV as a function of differentiation in an in vitro organotypic raft culture system which allows for epithelial stratification at the air-liquid interface. When CIN612 cells, which contain episomal copies of HPV type 31b (HPV31b), were allowed to stratify in raft cultures, they differentiated in a manner which was histologically similar to that seen in a cervical intraepithelial neoplasia I biopsy lesion. In monolayer cultures of CIN612 cells, two major polycistronic HPV31b transcripts of 1.7 kb which encode (i) E6, E7, E1-E4, and E5 and (ii) E6*, E7, E1-E4, and E5 were identified. These RNAs initiated at a promoter, P97, in the upstream regulatory region of the virus. Following differentiation in raft cultures, the relative abundance of RNAs initiated at P97 was unchanged. In contrast, the expression of a 1.3-kb RNA encoding an E1-E4 fusion protein and E5 was found to increase substantially following differentiation. This transcript was initiated at a novel promoter within the E7 gene (P742). These studies have therefore identified a constitutive viral promoter which is active throughout stratified epithelium as well as a novel promoter which is induced upon epithelial cell differentiation.

Amino Acid Sequence↗

PubMed1991

Therapeutic potential of plant photosensitizers.

Many bioactive phytochemicals have been shown in recent years to be photosensitizers, i.e. their toxic activities against viruses, micro-organisms, insects or cells are dependent on or are augmented by light of certain wavelengths. These activities are often selective, and this has led to the concept of therapeutic prospects in the control of infectious diseases, pests and cancer. Reaction mechanisms commonly involve singlet oxygen and radicals, which are thought to cause photodamage to membranes or macromolecules. The main classes of plant photosensitizers reviewed here are polyyines (acetylenes, thiophenes and related compounds); furanyl compounds; beta-carbolines and other alkaloids; and complex quinones. We propose that within each group of phytochemicals there are several representatives that merit further study for therapeutic abilities in appropriate animal models.

Animals↗

PubMed1991

Antiviral activities of hypericin.

Hypericin, a photodynamic plant quinone, readily inactivated murine cytomegalovirus (MCMV), Sindbis virus, and human immunodeficiency virus type 1 (HIV-1), especially on exposure to fluorescent light. Sindbis virus was significantly more sensitive than MCMV. The inactivated MCMV, when used to infect cells, was incapable of synthesizing early or late viral antigens. In addition to this direct virucidal effect, when hypericin was added to cells infected with viable MCMV, inhibition was also observed, particularly when the compound was added in the first two hours of infection. Again the antiviral effect was augmented by visible light. At effective antiviral concentrations, there were no discernible adverse effects on cultured cells. Thus hypericin appears to have two modes of antiviral activity: one directed at the virions, possibly on membrane components (although other virion targets cannot be ruled out), and the other directed at virus-infected cells. Both activities are substantially enhanced by light. Other recent studies on the antiviral activities of hypericin have not considered the role of light, and it is conceivable that apparent discrepancies between their results may have reflected different conditions of light exposure.

Animals↗

PubMed1991

Screening of medicinal plants from Yunnan Province in southwest China for antiviral activity.

In an ethnopharmacological screening of medicinal plants used in Yunnan province of China, ethanol extracts from 31 plant species were assayed for inhibition of murine cytomegalovirus and Sindbis virus infections. Parallel assays were carried out with and without exposure to UVA radiation to test for photo-mediation of activity. Antiviral activity was observed with 16 of the plant extracts. Eight plant extracts have been selected for further studies, with the objective of characterizing the antiviral constituents.

Antiviral Agents↗

PubMed1991

Ultraviolet-dependent biological activities of selected polyines of the asteraceae.

A series of eight polyines, isolated from several plants and containing various furanyl, thiophene, and spiro groups, were evaluated for antibiotic, antiviral, and cytotoxic activities in the presence and absence of long wavelength ultraviolet light, UVA. One compound, a furanopolyine, had impressive activity against a range of microorganisms, and membrane-containing viruses, as well as cytotoxic activity. All of these properties were UVA-dependent. Three other similar compounds had different patterns of UV-dependent activity against the various organisms, but some of these could also be of use in therapy of infectious diseases. In contrast, the dehydromatricaria esters and the two spiro compounds had relatively little biological activity.

Alkenes↗

PubMed1991

Antiviral activity of the photoactive plant pigment hypericin.

The polycyclic compound hypericin, a known photodynamic agent, was investigated for antiviral activity in the presence and absence of light. The three viruses tested: murine cytomegalovirus; Sindbis virus; and human immunodeficiency virus type 1, were all susceptible to hypericin; but these antiviral activities were considerably enhanced, in a dose-dependent manner, by exposure to light.

Animals↗

PubMed1991

Amplification of human papillomavirus genomes in vitro is dependent on epithelial differentiation.

Human papillomaviruses (HPVs) infect squamous epithelium and establish their genomes as episomes in proliferating basal cells. As infected cells differentiate, the viral DNA is amplified to high copy number and infectious virus is produced. Viral production has not yet been observed in vitro due to the inability of standard culture methods to duplicate most stages of epithelial differentiation. In this study, we have examined a cell line derived from a low-grade cervical lesion and found that it contained episomal copies of an HPV-31 subtype, HPV-31b, at approximately 50 copies per cell. When allowed to stratify at the air-liquid interface of in vitro raft cultures, this cell line differentiates in a manner which histologically resembles a low-grade cervical lesion in vivo. We have observed the amplification of HPV-31b genomes in distinct foci in the upper portion of the in vitro-stratified epithelium similar to that found in productive HPV infections in vivo. Although transcripts from the late region of HPV-31b were also detected specifically in stratified raft cultures, no capsid protein was found. These studies duplicate one important aspect of a productive HPV infection in vitro, the differentiation-dependent amplification of papillomavirus genomes.

Blotting, Northern↗

PubMed1990

Immortalization and altered differentiation of human keratinocytes in vitro by the E6 and E7 open reading frames of human papillomavirus type 18.

The E6-E7 region of human papillomavirus types 16 and 18 is selectively retained and expressed in cervical carcinoma cells. In cultured human keratinocytes, expression of the E6 and E7 open reading frames of human papillomavirus type 18, under the control of its homologous promoter, resulted in high-frequency immortalization. Furthermore, by using a system that allows for stratification of keratinocytes in vitro (raft system), we observed that the morphological differentiation of these E6-E7 immortalized cells was altered such that parabasal cells extended throughout most of the epithelium, with abnormal nuclei present in the upper regions. Examination of E6-E7-expressing cell lines in the raft system at a later passage revealed that complete loss of morphological differentiation had occurred. E7 alone was a much less effective immortalizing agent than E6 and E7 together and acted only minimally to alter morphological differentiation in vitro. No such activities were found for E6 alone. High-frequency transformation of human epithelial cells thus appears to require expression of both E6 and E7 gene products.

Cell Differentiation↗

PubMed1990

In vitro differentiation of epithelial cells from cervical neoplasias resembles in vivo lesions.

Cell lines derived from cervical neoplasias, as well as cells from normal cervix and neonatal foreskin were examined in an in vitro culture system (raft system) that allows for stratification and differentiation of epithelial cells at an air-liquid interface. Epithelial cells from human foreskin and ectocervix were observed to differentiate in a manner histologically similar to normal epithelium in vivo as indicated by a single layer of basal cells with a defined mid and upper zone. In contrast, cells expanded from cervical squamous carcinoma explants showed total absence of normal differentiation in the raft system with numerous cells in the upper portion of the stratum exhibiting mitotic figures. Cell cultures derived from low grade cervical intraepithelial neoplasia and condyloma acuminata exhibited partial differentiation in addition to perinuclear clearing, binucleate cells and individual cell keratinization. These studies show that in the raft system, cultured cells derived from tissue biopsies can duplicate many of the histological features observed in cervical neoplasias. In addition, epithelial cells derived from normal fetal ectocervix and electroporated with cloned human papillomavirus (HPV) type 16 DNA exhibited abnormal differentiation patterns similar to those of cervical intraepithelial neoplasia in vivo. This model system will thus be useful for examining the effects of HPV infection on epithelial maturation and for investigating the role of other factors in the progression of cervical malignancies.

Cell Differentiation↗

PubMed1989

Properties of the immunosuppressive factor induced by murine cytomegalovirus.

Murine cytomegalovirus infection of spleen cultures induced the production of a small (less than 10,000 molecular weight) immunosuppressive factor (VISF), which suppressed concanavalin-A mitogenesis in fresh mouse spleen cells, and in fresh human peripheral blood leukocytes. The factor did not affect the growth of two murine T-cell lines or of mouse fibroblasts. A similar factor was also found in the serum of infected mice, at the time of maximum immune suppression. The properties of VISF indicate that the mechanism of MCMV immune suppression is different from that caused by several other viruses which are important in human and veterinary medicine.

Animals↗