High mutagenicity and toxicity of a diol epoxide derived from benzo[a]pyrene

(±)-7β,8α-Dihydroxy-9β,10β-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BP 7,8-diol-9,10-epoxide) is a suspected metabolite of benzo[a]pyrene that is highly mutagenic and toxic in several strains of $\text{Salmonella}\text{typhimurium}$ and in cultured Chinese hamster V79 cells. BP 7,8-diol-9,10-epoxide was approximately 5, 10 and 40 times more mutagenic than benzo[a]pyrene 4,5-oxide (BP 4,5-oxide) in strains TA 98 and TA 100 of $\text{S.}\text{typhimurium}$ and in V79 cells, respectively. Both compounds were equally mutagenic to strain TA 1538 and non-mutagenic to strain TA 1535 of $\text{S.}\text{typhimurium}$. The diol epoxide was toxic to the four bacterial strains at 0.5–2.0 nmole/plate, whereas BP 4,5-oxide was nontoxic at these concentrations. In V79 cells, the diol epoxide was about 60-fold more cytotoxic than BP 4,5-oxide.     

Effect of beta-xylosides on synthesis of cartilage-specific proteoglycan in chondrocyte cultures.

Monolayer cultures of embryonic chick chondrocytes were incubated with ³⁵SO₄ in the presence and absence of 1.0 mM p-nitrophenyl-β-D-xylose for 2 days. The relative amounts of chondroitin sulfate proteoglycan and free chondroitin sulfate chains were measured following gel filtration on Sephadex G-200. Synthesis of β-xyloside-initiated polysaccharide chains was accompanied by an apparent decrease in chondroitin sulfate proteoglycan production by the treated cultures. The amount of core protein was determined from equivalent numbers of β-xyloside-treated and untreated cells by a radioimmune assay. Similar amounts of core protein were found in both types of cultures, indicating that decreased synthesis of cartilage-specific core protein is not responsible for the observed decrease in overall chondroitin sulfate proteoglycan production.     

In vivo and in vitro fertilization of hamster, rat and mouse eggs after treatment with anti-hamster ovary antiserum.

Rabbit antiserum against hamster ovary was examined on agargel diffusion plates against several hamster tissues, and also against rat and mouse ovarian extracts. Unabsorbed anti-hamster ovary antiserum showed eight to nine precipitin bands for hamster ovary and four to eight bands for other tissue extracts, but no bands against sperm antigens. Anti-hamster ovary antiserum also showed three to four bands for rat and one to two bands for mouse ovarian extracts. The present experiments confirmed previous reports for the hamster and mouse that treatment of eggs with anti-ovary antiserum blocked in vitro fertilization and that the extent of the inhibition was related to the formation of a precipitate on the zone pellucida. A single injection of anti-hamster ovary antiserum inhibited fertilization in mice but not in rats. In vitro fertilization of mouse eggs was also inhibited in the presence of such antiserum.     

Permselectivity of the glomerular capillary wall to macromolecules. I. Theoretical considerations.

The transport of macromolecules across the renal glomerular capillary wall has been described theoretically using flux equations based on (a) restricted transport through small pores, and (b) the Kedem-Katchalsky formulation. The various assumptions and limitations inherent in these two approaches are discussed. To examine the coupling between macromolecular solute transport and the determinants of glomerular filtration rate, these flux equations were combined with mass balance relations which allow for variations in the transmembrane driving forces along a glomerular capillary. It was predicted, using both pore theory and the Kedem-Katchalsky equations, that fractional solute clearance should be strongly dependent on the determinants of glomerular filtration rate when convection and diffusion both contribute to solute transport. When convection becomes the sole mechanism for transcapillary solute transport, however, fractional solute clearance is essentially independent of changes in the determinants of glomerular filtration rate. Consequently, unless diffusion is absent, fractional solute clearances alone are insufficient to characterize the permselective properties of the glomerular capillary wall, since these values may be altered by changes in glomerular pressures and flows as well as changes in the properties of the capillary wall per se.     

Removal of Enteroviruses from Sewage by Bench-Scale Rotary-Tube Trickling Filters

The efficacy of a rotary-tube type of trickling filter for removing coxsackievirus A9, poliovirus 1, and echovirus 12 suspended in raw settled sewage was investigated. At filtration rates equivalent to about 10 MGD (million gallons per day)/acre (ca. 3,785 m3/day per acre), the filters removed 95% of the poliovirus, 83% of echovirus 12, and 94% of coxsackievirus A9. Coliform, fecal streptococci, biochemical oxygen demand, and chemical oxygen demand removals were remarkably similar, averaging 94, 92, 93, and 95%, respectively. At filtration rates equivalent to about 23 MGD/acre, 59% of the poliovirus, 63% of the echovirus 23, and 81% of the coxsackievirus A9 were removed. Coliform, fecal streptococci, biochemical oxygen demand, and chemical oxygen demand removals at this filtration rate were 68, 75, 72, and 56%, respectively. Viruses were assumed to be adsorbed to the biological slime growing in the filters, but attempts to disassociate the viruses from the slime were unsuccessful, indicating that the slime-virus complex is very stable or that the viruses were somehow inactivated. The data indicate that coliform and fecal streptococci reductions in this type sewage treatment process can be used as an index of virus reduction. Disinfection, however, must be used to ensure a virus-free final effluent.     

Fate of ochratoxin A in brewing.

The fate of ochratoxin A in brewing was investigated by adding (3H)ochratoxin A to the raw materials at 1- and 10-mug/g levels during mashing in a conventional microbrewing process. The results indicated that large portions (28 to 39%) of the added toxin were recovered in spent grains, with less recovery in the yeast (8 to 20%) and beer (14 to 18%). About 38 and 12% of the added toxin at levels of 1 and 10 mug/g, respectively, were degraded during brewing.     

Quantitative aspects of hormone-receptor interactions of high affinity: Effect of receptor concentration and measurement of dissociation constants of labeled and unlabeled hormones

It is demonstrated that because of limitations in the magnitude of the specific activity of radiolabeled hormone derivatives, direct binding studies of hormone-receptor interactions of high affinity (10^?9–10^?11 M, depending on whether ³H- or ¹²³I-labeled hormones are used) will be subject to artifactual distortions due to the need to utilize high concentrations of the receptor. If the concentration of the receptor is not ten times lower than the true affinity constant, the apparent dissociation constant obtained from direct concentration binding curves will vary as a linear function of the receptor concentration. In addition, at high receptor concentrations saturability becomes difficult to demonstrate experimentally and the binding data yield apparently non-hyperbolic, sigmoidal curves which can be mistakenly interpreted to depict cooperative interactions. Similar artifacts related to receptor concentration are predicted for measurements of the hormone concentration dependence of biological processes (e.g. activation of adenylate cyclase, transport processes, etc.). Methods for detecting these effects, and correctly measuring affinities for labeled and unlabeled hormones under these conditions, are described. The implications for measuring the binding properties of hormone-receptor interactions are discussed, especially in reference to studies of the comparative analysis of receptor function in altered metabolic states and to studies relating the biological and binding properties of hormones.