Chlorination of Indicator Bacteria and Viruses in Primary Sewage Effluent

Wastewater disinfection is used in many countries for reducing fecal coliform levels in effluents. Disinfection is therefore frequently used to improve recreational bathing waters which do not comply with microbiological standards. It is unknown whether human enteric viruses (which are responsible for waterborne disease) are simultaneously inactivated alongside fecal coliforms. This laboratory study focused on the chlorination of primary treated effluent with three doses (8, 16, and 30 mg/liter) of free chlorine as sodium hypochlorite. Seeding experiments showed that inactivation (>5 log₁₀ units) of Escherichia coli and Enterococcus faecalis was rapid and complete but that there was poor inactivation (0.2 to 1.0 log₁₀ unit) of F⁺-specific RNA (FRNA) bacteriophage (MS2) (a potential virus indicator) at all three doses. However, seeded poliovirus was significantly more susceptible (2.8 log₁₀ units) to inactivation by chlorine than was the FRNA bacteriophage. To ensure that these results were not artifacts of the seeding process, comparisons were made between inactivation rates of laboratory-seeded organisms in sterilized sewage and inactivation rates of organisms occurring naturally in sewage. Multifactorial analysis of variance showed that there was no significant difference (P > 0.05) between the inactivation rates for seeded and naturally occurring FRNA bacteriophage. However, laboratory-grown poliovirus was inactivated much more rapidly than were naturally occurring, indigenous enteroviruses (P < 0.001). This may reflect differences in the way indigenous virus is presented to the disinfectant. Inactivation rates for indigenous enteroviruses were quite similar to those seen for FRNA bacteriophage at lower doses of chlorine. These results have significance for the effectiveness of chlorination as a sewage treatment process, particularly where virus contamination is of concern, and suggest that FRNA bacteriophage would be an appropriate indicator of such viral inactivation under field conditions.     

Interobserver error in human skin colorimetry

Twenty light-skinned adults were measured at the upper inner arm site using two commonly used reflectance spectrophotometers. Each subject was measured by each of three investigators to assess the influence of interobserver error on the reflectance readings. A repeated measures design analysis of variance showed no significant variance component due to observers.     

The nature of the β-adrenoceptor involved in the inhibition of antigen-induced histamine release

Antigen stimulated release of histamine from chopped sensitized guinea-pig lung is inhibited by the addition of β-adrenoceptor agonists in a manner indicating a β₂ response. Preaddition of β-adrenoceptor antagonists blocks this inhibition in a manner indicating a β₁ response. This apparent dichotomy probably results from a hybrid receptor, though the danger of the use of chemical analogues for classifying receptors is highlighted. Inhibition of histamine release by β-stimulation is shown to be species rather than organ specific.     

The in vitro biosynthesis of dhurrin, the cyanogenic glycoside of Sorghum bicolor.

A microsomal fraction from seedlings of Sorghum bicolor (Linn) Moench has been shown to catalyze the conversion of L-tyrosine to p-hydroxymandelonitrile via p-hydroxyphenylacetaldoxime. This transformation is consistent with the general pathway for cyanogenic glycoside biosynthesis proposed on the basis of in vivo experiments. When the microsomal fraction was combined with a protein fraction from the soluble portion of the cell and uridine diphosphate glucose, it was possible to demonstrate the synthesis of the cyanogenic glycoside dhurrin from L-tyrosine.     

Effect of ion removal on the solubility of rat brain proteins in chloroform-methanol mixtures

—The amount of chloroform-methanol-soluble protein obtained from rat brain tissue homogenates which have been subjected to washing by repeated contrifugation or dialysis is a several-fold greater than that obtained from untreated homogenates. The increase consequence of the removal of loosely bound electrolytes during the process of centrifugation or dialysis: little or no increase is observed upon (a) the addition of the supernatant, the ashed supernatant, or the diffusate to the washed homogenate; (b) the addition of inorganic salts to the washed homogenate; or (c) washing of the homogenate with a salt solution. The previously observed effect of sucrose in increasing the amount of chloroform–methanol-soluble protein obtained from subcellular fractions is apparently superimposed upon the effect of the removal of salts.