Round robin investigation of methods for recovering human enteric viruses from sludge

To select a tentative standard method for detection of viruses in sludge the American Society for Testing and Materials D19:24:04:04 Subcommittee Task Group initiated round robin comparative testing of two procedures that, after initial screening of several methodologies, were found to meet the basic criteria considered essential by the task group. Eight task group member laboratories agreed to perform round robin testing of the two candidate methods, namely, The Environmental Protection Agency or low pH-AlCl3 method and the Glass or sonication-extraction method. Five different types of sludge were tested. For each particular type of sludge, a single laboratory was designated to collect the sludge in a single sampling, make samples, and ship it to the participating laboratories. In most cases, participating laboratories completed all the tests within 48 h of sample arrival. To establish the reproducibility of the methods, each laboratory tested each sludge sample in triplicate for the two candidate virus methods. Each processed sludge sample was quantitatively assayed for viruses by the procedures of each individual round robin laboratory. To attain a more uniform standard of comparison, a sample of each processed sample from all laboratories was reassayed with one cell line and passage number by a single laboratory (Environmental Protection Agency Environmental Monitoring and Support Laboratory, Cincinnati, Ohio). When the data were statistically analyzed, the Environmental Protection Agency method was found to yield slightly higher virus recoveries for all sludge types, except the dewatered sludge. The precisions of both methods were not significantly different.(ABSTRACT TRUNCATED AT 250 WORDS)     

Inhibition of rabbit reticulocyte lysate protein synthesis by heavy metal ions involves the phosphorylation of the alpha-subunit of the eukaryotic initiation factor 2

The effect of heavy metal ions (in particular Cd2+, Hg2+, and Pb2+) on protein synthesis in hemin-supplemented reticulocyte lysates was investigated. Heavy metal ions were found to inhibit protein synthesis in hemin-supplemented lysates with biphasic kinetics. The shut off of protein synthesis occurred in conjunction with the phosphorylation of the alpha-subunit of the eukaryotic initiation factor (eIF) 2, the loss of reversing factor (RF) activity, and the disaggregation of polyribosomes. Addition of eIF-2 or RF to heavy metal ion-inhibited lysates restored protein synthesis to levels observed in hemin-supplemented controls. The stimulation of protein synthesis observed upon the addition of cAMP to heavy metal ion-inhibited lysates correlated with the inhibition of eIF-2 alpha phosphorylation and the restoration of RF activity. The partial restoration of protein synthesis observed upon the addition of MgGTP to heavy metal ion-inhibited lysates correlated with a partial inhibition of eIF-2 alpha phosphorylation. Addition of glucose 6-phosphate was found to have no effect on protein synthesis of eIF-2 alpha phosphorylation under these conditions. Antiserum raised to the reticulocyte heme-regulated eIF-2 alpha kinase inhibited the phosphorylation of eIF-2 alpha catalyzed by Hg2+-inhibited lysate. The inhibition of protein synthesis observed in the presence of heavy metal ions correlated with the relative biological toxicity of the ions. Highly toxic ions (AsO-2, Cd2+, Hg2+, Pb2+) inhibited protein synthesis by 50% at concentrations of 2.5-10 microM. Cu2+, Fe3+, and Zn2+, which are moderately to slightly toxic ions, inhibited protein synthesis by 50% at concentrations of 40, 250, and 300 microM, respectively. The data presented here indicate that heavy metal ions inhibit protein chain initiation in hemin-supplemented lysates by stimulating the phosphorylation of eIF-2 alpha apparently through the activation of the heme-regulated eIF-2 alpha kinase rather than through inhibition of the rate of eIF-2 alpha dephosphorylation.     

Effects of the lipid peroxidation product 4-hydroxynonenal on the aggregation of human platelets

The stimulation by ADP or arachidonic acid of the aggregation of human platelets in plasma was inhibited by 4-hydroxynonenal (HNE). This reduction of aggregation was time related, and was increased by prolonged preincubation of the platelets with the aldehyde. HNE was more potent than its homologue 4-hydroxypentenal (HPE). HNE was less active in decreasing the aggregation induced by calcium ionophore A23187 or collagen in comparison with ADP. HNE was inactive against aggregation of platelet-rich plasma (PRP) stimulated by thrombin whereas it potently inhibited the aggregation of washed platelets in response to both thrombin and collagen. Platelets were found to degrade HNE, and mechanisms additional to covalent binding to glutathione are indicated by the results obtained. The aldehydes, including HNE, generated by platelets originated principally from arachidonic acid metabolism.     

The roles of phospholipase D and a GTP-binding protein in guanosine 5''-[gamma-thio]triphosphate-stimulated hydrolysis of phosphatidylcholine in rat liver plasma membranes.

1. Guanosine 5'-[gamma-thio]triphosphate (GTP[S]) stimulated by 50% the rate of release of [3H]choline and [3H]phosphorylcholine in rat liver plasma membranes labelled with [3H]choline. About 70% of the radioactivity released in the presence of GTP[S] was [3H]choline and 30% was [3H]phosphorylcholine. 2. The hydrolysis of phosphorylcholine to choline and the conversion of choline to phosphorylcholine did not contribute to the formation of [3H]choline and [3H]phosphorylcholine respectively. 3. The release of [3H]choline from membranes was inhibited by low concentrations of SDS or Triton X-100. Considerably higher concentrations of the detergents were required to inhibit the release of [3H]phosphorylcholine. 4. Guanosine 5'-[beta gamma-imido]triphosphate and guanosine 5'-[alpha beta-methylene]triphosphate, but not adenosine 5'-[gamma-thio]-triphosphate, stimulated [3H]choline release to the same extent as did GTP[S]. The GTP[S]-stimulated [3H]choline release was inhibited by guanosine 5'-[beta-thio]diphosphate, GDP and GTP but not by GMP. 5. It is concluded that, in rat liver plasma membranes, (a) GTP[S]-stimulated hydrolysis of phosphatidylcholine is catalysed predominantly by phospholipase D with some contribution from phospholipase C, and (b) the stimulation of phosphatidylcholine hydrolysis by GTP[s] occurs via a GTP-binding regulatory protein.     

Survival of indigenous enteric viruses during storage of waste water sludge samples

The stability of indigenous enteric viruses in samples of settled primary and mixed-liquor activated sludges was studied at 2, 23, and -70 degrees C. Changes of virus titer which occurred in these samples were followed during an 84-day observation period, with rates of change then calculated by least-squares regression. Virus survival was found to be statistically dependent (p less than or equal to 0.05) upon storage temperature but not sludge solids content. Based upon the observed rates of inactivation, the average times which would be required for a 90% decrease in virus titer are 26 days at 23 degrees C, 180 days at 2 degrees C, and 163 days at -70 degrees C. As a group, the rates of virus inactivation observed at 2 degrees C were statistically different (p less than or equal to 0.05) from those observed at 23 degrees C, but not different from those observed at -70 degrees C. The three study temperatures were selected to approximate holding of samples in an air-conditioned room, on wet ice (H2O), and on dry ice (CO2).