Induction of sister chromatid exchange by various selenium compounds in Chinese hamster cells in the presence and absence of S9 mixture

This study was designed to investigate the effect of 3 selenium compounds, namely, sodium selenite, sodium selenide and sodium selenate on induction of sister chromatid exchange (SCE) in the Chinese hamster V79 cell line in the presence and absence of S9 mixture. The results indicated that the most potent SCE inducer in the presence of S9 mixture was sodium selenite and this was followed by sodium selenide, while in the absence of S9 mixture the most effective SCE inducer was sodium selenide which was then followed by sodium selenite. For sodium selenate, the data indicated no increase in SCE rate as compared to the control values both in the presence and absence of S9 mixture. In addition, it was observed that growth inhibition as measured by no sister chromatid differentiation or no metaphases was produced by certain doses of the compounds tested. Based on this, the compound that induced the most growth inhibition both in the presence and absence of S9 mixture was sodium selenide and this was followed by sodium selenite. For sodium selenate no growth inhibition was observed. The different capabilities of the selenium compounds tested to induce SCE were clearly demonstrated in the system employed in this study. It is felt that this effect is an important cytogenetic characteristic of these compounds, yet how this activity relates to the antimutagenic and anticarcinogenic properties of these agents is difficult to discern.

Collagenase activity in squamous cell carcinoma of the human parotid gland

A collagenase obtained from a single squamous cell carcinoma of human parotid gland was purified to homogeneity by procedures including precipitation with ammonium sulfate, gel filtration, ion-exchange chromatography with DEAE-cellulose, and extraction from polyacrylamide gel after electrophoresis. The parotid tumor collagenase had a molecular weight of approximately 68,000 and appeared similar to other mammalian collagenases in many respects such as action on collagen and response to common collagenase inhibitors. Analysis of specimens of various human parotid gland tumors revealed that the levels of collagenase activity were higher in squamous cell carcinoma than in nonsquamous tumors. A high level of collagenase activity from squamous cell carcinoma suggests that collagenase may promote local connective tissue destruction associated with tumor invasion and lymph node metastasis.

Sister-chromatid exchanges and cell-cycle delay in Chinese hamster V79 cells treated with 9 organophosphorus compounds (8 pesticides and 1 defoliant)

Significant increase of sister-chromatid exchanges (SCE) in V79 cells treated with 2 organophosphorus pesticides (OPP), fenthion and oxydemeton-methyl, was observed. The other 7 compounds (6 OPP and 1 defoliant) namely, amaze, azinphos-methyl, bolstar, DEF-defoliant, fensulfothion, monitor and nemacur caused no increase of SCE frequencies at the doses tested. All the compounds except fensulfothion and oxydemeton-methyl induced cell-cycle delay in varying degrees. Cell-cycle delay caused by an OPP was found to be dose-dependent. Based on these data as well as others reported, it would appear that OPP which induce no SCE increase and no or slight cell-cycle delay could be considered as good candidates to substitute the pesticides that have been found to be harmful to the environment.

Retinol (vitamin A) inhibits sister chromatid exchanges and cell cycle delay induced by cyclophosphamide and aflatoxin B1 in Chinese hamster V79 cells

Retinol (vitamin A alcohol) at the doses tested neither induced an increase of frequency of sister chromatid exchanges (SCE) nor cell cycle delay in Chinese hamster V79 cells with or without the metabolic activation of S-9 mix. However, it inhibited SCE frequencies and cell cycle delay in V79 cells induced by the indirect mutagen cyclophosphamide or aflatoxin B1. The inhibition was found to be dose and time dependent. These results suggest that retinol itself may have no direct effect on the genetic materials but rather exert its effects possibly by inhibiting the metabolic activation of an indirect mutagen or carcinogen. Thus, the antitumor activities of retinoids may not be limited to the widely accepted role of preventing the promotion step but also the initiation step of carcinogenesis.

Fine mapping of secondary structures of fd phage DNA in the region of the replication origin

A synthetic heptaribonucleotide, GACCCCC, which is complementary to a unique site on fd bacteriophage DNA, primes DNA synthesis of fd by T4 bacteriophage DNA polymerase. The rate of the GACCCCC-primed DNA synthesis was not uniform as reflected by the appearance of discrete DNA fragments as replication intermediates on an alkaline agarose gel. After 10 minutes of synthesis a significant fraction of the DNA product ran as a single band with a length of about 1960 nucleotides. We have isolated this DNA fragment, hybridized back to unlabeled fd DNA template, and mapped the Taq I restriction fragments by urea polyacrylamide gel electrophoresis. This fine mapping procedure has located two major pause sites at fd nucleotide positions 5575 and 5674. These sites reside in the stem of two very stable hairpin helices near the origin of DNA replication of fd. Models for the functional roles of these two hairpin helices are presented.

Effects of retinoids on plating efficiency, sister-chromatid exchange (SCE) and mitomycin-C-induced SCE in cultured Chinese hamster cells

The effects of 5 retinoids, namely, all-trans-retinol (ROL), all-trans-retinoic acid (RA), all-trans-retinal (RAL), all-trans-retinyl acetate (RAc), and Ro. 10-9359-TMMP ethyl retinoate on plating efficiency, sister-chromatid exchange (SCE) and on mitomycin-C (MMC)-induced SCE were studied in Chinese hamster V79 cells. All the retinoids caused reduction of plating efficiency in a dose-dependent manner but the degree of plating efficiency reduction varied considerably among the retinoids studies. RAL was the most potent reducer of plating efficiency and this was followed in decreasing order by ROL, RAc, RA and Ro. 10-9359. For the effect of various doses of retinoids on SCE, it was clearly demonstrated that addition of each of the 5 retinoids to exponentially growing V79 cells had no significant effect on SCE frequency as compared to the controls. Besides this, these compounds did not alter DCS frequency induced by MMC.

Prostaglandin E2, collagenase, and protease levels in culture of rat tumor

The production of collagenase, protease, leucine aminopeptidase, and prostaglandin E2 by rat tumor increased with the growth of tumor. The syntheses of collagenase, protease, and leucine aminopeptidase were significantly inhibited by indomethacin. Inhibition of collagenase, protease, and leucine aminopeptidase syntheses was overcome by the addition of prostaglandin E2 at a concentration equivalent to the endogenous level of prostaglandin E2 in rat tumor. These findings suggested that prostaglandin E2, possibly derived from tumor cells, was involved in stimulating the tumor connective tissue stroma to produce collagenase, protease, and leucine aminopeptidase, which promoted tumor cell invasion.

Effect of tumor promoter 12-O-tetradecanoyl-phorbol 13-acetate on induction of sister-chromatid exchanges in Chinese hamster V79 cells treated with mutagens

The effect of a tumor promoter, 12-O-tetradecanoyl-phorbol 13-acetate (TPA) alone and in combination with mitomycin C (MMC) or cyclophosphamide (CPP) on the induction of sister-chromatid exchanges (SCE) in Chinese hamster V79 cells was investigated. TPA alone at various doses and durations caused no increase of SCE frequency. MMC either at the dose of 0.03 or 0.003 microgram/ml alone or in combination with TPA (2 microgram/ml) all caused a significant increase of SCE frequencies. There was no difference in SCE frequencies between the cultures treated with MMC alone at 0.03 microgram/ml and those treated with MMC plus TPA. However, cultures treated with MMC at 0.003 microgram/ml plus TPA had significantly and consistently higher SCE frequencies than those treated with MMC alone at all durations. Treatment of CPP at 1 microgram/ml activated by S9 mix caused significant increase of SCE frequencies. Surprisingly, the cultures treated with CPP, S9 mix plus TPA (2 microgram/ml) caused a drastic reduction of SCE frequencies as compared to those treated with CPP and S9 mix only at all durations. These results indicate that TPA alone had no effect on SCE in V79 cells. TPA enhanced the SCE induction in V79 cells treated with MMC at a low dose, i.e. 0.003 microgram/ml, but it inhibited SCE induction in cultures treated with the indirect mutagen CPP. Thus, TPA has no direct effect on genetic materials but it may indirectly alter the effects of a mutagen.

Two types of replication proteins increase the rate at which T4 DNA polymerase traverses the helical regions in a single-stranded DNA template

We have recently developed an in vitro DNA synthesis system in which a synthetic heptaribonucleotide pairs with a unique site on a single-stranded fd DNA molecule and thereby primes the growth of new DNA strands from this single point (Huang, C.-C., and Hearst, J. E. (1980) Anal. Biochem. 103, 127-139). In this report, we use this system to investigate the mechanism by which various bacteriophage T4 DNA replication proteins stimulate the T4 DNA polymerase. We find that with the "polymerase accessory proteins" present (the T4 gene 44/62 and 45 proteins), the DNA polymerase proceeds rather rapidly through the occasional hairpin helices which otherwise interrupt the progress of this enzyme along single-stranded DNA templates. By using a potent inhibitor of the 44/62 ATPase, ATP gamma S (adenosine 5'-O-(3-thiotriphosphate)), we have obtained data which suggest that ATP hydrolysis is required for the formation of a polymerase accessory protein-DNA template complex, and that this complex then persists, serving as a sliding clamp which greatly increases the strength of binding between a T4 DNA polymerase molecule and its 3'OH primer template end. The progress of the T4 DNA polymerase though hairpin helices in the DNA template is also stimulated by addition of the T4 helix-destabilizing protein (gene 32 protein). The effect of the 44/62 and 45 proteins is independent of the effect of the 32 protein in this assay, and the rate of polymerase travel over the strongest hairpin helices is increased more than 40-fold in the presence of these four additional proteins.

Induction of sister-chromatid exchanges and cell cycle delay in cultured mammalian cells treated with eight organophosphorus pesticides

Induction of sister-chromatid exchanges (SCE) and cell cycle delay in Chinese hamster cell line V79 after treatment with 8 organophosphorus pesticides (OPP) were studied. In addition, these effects were also studied using 1 of the 8 OPP in 2 human lymphoid cell lines. In V79 cells, 6 of the 8 OPP induced significant increase of frequencies of SCE and all the OPP induced various degrees of cell cycle delay. The 6 OPP in decreasing order of SCE induction are methylparathion, demeton, trichlorfon, dimethoate, malathion and methidathion. The 2 OPP that had no effect on SCE are diazion and disyston. The extents of induced cell cycle delay are generally related to the OPP concentrations but does not necessarily correlate with the extent of induction of SCE among the OPP studied. The results of studies on the effect of methyl-parathion on SCE and cell cycle delay in 2 human cell lines showed that both lines had significant and dose-dependent increase of SCE frequencies similar to those observed in V79 cells. In contrast to V79 cells, however, cell cycle delay was not as prominent in the human lines at comparable doses. These studies indicated that 5-bromodeoxyuridine labeling for analyzing SCE and cell cycle delay is a very sensitive method in assessing mutagenic potential of environmental compounds especially those that are highly toxic to and rapidly degradable in mammalian cells such as OPP.

Reserpine and alpha-methyldopa in the treatment of tardive dyskinesia

Thirty inpatients with evidence of tardive dyskinesia secondary to antipsychotic medications participated in this double-blind, controlled, randomized study comparing reserpine, alpha-methyldopa and placebo. Reserpine at doses of 0.75--1.5 mg daily, or alpha-methyldopa at doses of 750--1,500 mg daily, produced a statistically significant improvement in tardive dyskinesia symptomatology compared to the results obtained with placebo.

Collagenase and protease activities in head and neck tumors

An analysis of specimens of 43 head and neck tumors revealed that collagenase and protease activities paralleled each other and varied according to the anatomic site; highest activities were in tongues and tonsils, which are known to have low five-year survival rates. The greatest differences in both enzyme activities were observed in the studies of histologic patterns and tumor differentiation. The ulcerated tumors with inflammatory infiltrates having high enzyme activities suggest that collagenase and protease may be derived from inflammatory cells.

Sister chromatid exchanges and chromosome aberrations in V79 cells induced by aflatoxin B1, B2, G1 and G2 with or without metabolic activation

Cells from Chinese hamster cell line V79 were pulse treated for one hour with aflatoxin (AF) B1, B2, G1 and G2 at various doses with or without the metabolic activation system-S9 mix. With metabolic activation, all these toxins caused significant increases of frequencies of sister chromatid exchanges (SCE) in a dose-dependent manner. Based on the rate of SCE induction, the relative order of potency was established as AFB1 > G1 > G2 > B2. Without metabolic activation, all four toxins had no or very little effect over the same dose ranges used for SCE induction with activation. Induction of chromosome aberrations in V79 cells after a one hour pulse treatment with AFB1 and G1 plus S9 mix was also studied. A dose and time dependent increase of aberrations was observed for both compounds. AFB1 again is a more potent aberration inducer than AFG1.

Synthesis and biological evaluation of p-bromospiperone as potential neuroleptic drug

p-Bromospiperone was prepared from the reaction of spiperone with bromine. It was tested for dopamine receptor binding affinity in vitro and its ability to stimulate prolactin secretion in vivo. The results indicate no significant change of biological activities due to the bromination of spiperone.

In vivo stability and distribution of [131I]iodomethyl trimethylammonium chloride: concise communication

[131I]iodomethyl trimethylammonium chloride (I-131 TMA) was prepared by the isotope-exchange reaction of diiodomethane with Na131I, followed by reaction with trimethylamine. A specific activity of 20 microCi/mg was obtained. Tissue distributions following intravenous injection of I-131 TMA in mice showed that between 10 min and 2 hr, the highest accumulations of radioactivity were in the urine, kidney, and heart. The uptake of this compound in the heart was very rapid, and the levels of radioactivity remained fairly high up to 2 hr. At 10, 30, 60, and 120 min the heart-to-blood ratios were, respectively, 10.2, 7.7, 8.3, and 9.6. Thyroid uptake of this compound in the rats and analysis of urine samples of the mouse indicated no extensive deiodination of the compound in vivo. These results show that this compound does have potential for use in myocardial imaging. In addition, its stability in vivo makes it very useful for the radiolabeling of compounds containing quaternary ammonium moieties.

Comparison of induction of sister chromatid exchange, 8-azaguanine- and ouabain-resistant mutants by cyclophosphamide, ifosfamide and 1-(pyridyl-3)-3,3-dimethyltriazene in Chinese hamster cells cultured in diffusion chambers in mice

Data on induction of sister chromatid exchange (SCE), 8-azaguanine and ouabain-resistant mutants in V79 cells in diffusion chambers in mice treated with three chemicals were compared to determine the relationship between SCE and mutation. For 1-(pyridyl-3)-3,3-dimethyltriazene, a positive, linear correlation was demonstrated between induced SCE and mutation at both loci. For cyclophosphamide and ifosfamide, it was observed that SCE analysis was a more sensitive biological endpoint than induction of mutation.