Evaluating the transmission risk of SARS-CoV-2 from sewage pollution.

The presence of SARS-CoV-2 in untreated sewage has been confirmed in many countries but its incidence and infection risk in contaminated waters is poorly understood. The River Thames in the UK receives untreated sewage from 57 Combined Sewer Overflows (CSOs), with many discharging dozens of times per year. This study investigated if such discharges provide a pathway for environmental transmission of SARS-CoV-2. Samples of wastewater, surface water, and sediment collected close to six CSOs on the River Thames were assayed over eight months for SARS-CoV-2 RNA and infectious virus. Bivalves were also sampled as an indicator species of viral bioaccumulation. Sediment and water samples from the Danube and Sava rivers in Serbia, where raw sewage is also discharged in high volumes, were assayed as a positive control. No evidence of SARS-CoV-2 RNA or infectious virus was found in UK samples, in contrast to RNA positive samples from Serbia. Furthermore, this study shows that infectious SARS-CoV-2 inoculum is stable in Thames water and sediment for <3 days, while SARS-CoV-2 RNA is detectable for at least seven days. This indicates that dilution of wastewater likely limits environmental transmission, and that detection of viral RNA alone is not an indication of pathogen spillover.

Estimation of the isoleucine and aromatic amino acid requirements of pregnant swine.

The requirements of the pregnant gilt for isoleucine (Ile), total aromatic amino acids (TAAA), phenylalanine (Phe) and the replacement of Phe with tyrosine (Tyr) were investigated in these studies. Five balanced 6 x 6 latin-square arrangements of treatments and time periods were conducted with six pregnant gilts in each trial. Each diet treatment was fed (1.8 kg once daily) for 10 d beginning on d 40 of pregnancy. Nitrogen balance trials were conducted from the 6th to 10th d during each period. Blood samples were obtained from each gilt before and 2 h after the last feeding in each period. Based on the titration trials, the L-Ile requirement was satisfied at .23% of the diet. Assuming that crystalline L-Ile was 100% available, the L-Ile requirement for pregnant gilts fed a corn-soybean meal diet is estimated at .25%. A dietary requirement of no more than .43% satisfied all the criteria measured in the L-TAAA trial. Adjustment for availability of crystalline L-Phe used in the diets would increase the requirement to about .48% dietary L-TAAA. About 42% of the L-TAAA requirement for pregnancy should be supplied by L-Phe.

Enzyme content of hepatocellular lysosomes in the liver of the tumour-bearing mouse.

An increase in the number of hepatocellular lysosomes was not detected in mice bearing the solid or ascites forms of Sarcoma 180 or Ehrlich's tumour. Despite this, biochemical studies showed significant increases in acid phosphatase, cathepsin-D and beta-galactosidase. This difference between morphological and biochemical observations is explained by the fact that only gross increases in lysosome population are likely to be detected in the small samples examined with the electron microscope, but by biochemical methods whereby many grams of tissue are analysed finer changes may be detected. As far as is known at present there is an increase in hepatocellular lysosomes and/or lysosomal enzymes in tumour-bearing mice, rats and man and no exception to this exists.

Lysozyme production by a granuloma in vivo: output in blood and lymph in relation to ultrastructure and immunochemistry.

The output of lysozyme into the venous and lymphatic drainage of a B.C.G. experimental granuloma has been studied. There is a massive output of lysozyme by both routes maximal in the lymph at 28 days, and in the serum at 35 days after induction of the granuloma. There is no similar excretion of acid phosphatase. The lactic dehydrogenase level both in blood draining the granuloma and blood draining the normal limb is elevated but not in precise synchrony with lysozyme output. Macrophages in the granuloma show ultrastructural features suggestive of secretion of dense granules, by appearance of electron dense material in the Golgi zone, and condensation therefrom. Granules are discharged on to the surface of lipid droplets, presumably representing attempted phagocytosis, but are not discharged elsewhere on the cell surface. Granules are released by cell disintegration both of macrophages and polymorphs. Lysozyme was demonstrated immunocytochemically in macrophage granules. The macrophages in the granuloma are biosynthetically active as shown by uptake of tritiated tyrosine. The findings support the view that granulomas export lysozyme and that this is due partly to exocytosis of material by macrophages on to the surface of lipid globules and partly to cell disintegration.

Enzyme content of hepatocellular lysosomes in the tumour-bearing rat.

An increase in the number of hepatocellular lysosomes is detectable with the electron microscope in rats bearing a carcinogen-induced sarcoma but not in rats bearing a transplanted Walker tumour. Biochemical studies show an increase in lysosomal enzymes in the liver of both groups of rats, but the increase in the rats bearing a carcinogen-induced sarcoma was greater than that in rats bearing a Walker tumour. This difference is explained by the fact that only gross increases in lysosomal population are likely to be detected in the small samples examined with the electron microscope, but by biochemical methods whereby many grams of tissue are analysed, finer changes may be detected. The collective data to date indicate that an increase in hepatocellular lysosomes and/or lysosomal enzymes occurs in rats and man bearing a variety of tumours and to this there is, as yet, no known exception.

Comparison of 3-kit methods for determination of human chorionic somatomammotropin by radioimmunoassay.

1. Three commercially available kit procedures for human chorionic somatomammotropin (HCS) were investigated. 2. The comparison of the methods included procedure, accuracy, precision, sample requirement and time required for analyses. 3. While one kit gave significantly higher values and requires more time to obtain results, each of 3 procedures was concluded to provide clinically useful information.