Values,Errors, and Precautions

In the environmental health literature, errors in interpreting studies or data are not infrequent. Many are of the Type II variety. Common solecisms of this type are: treating the criterion of p < 0.05 as a sacrament; demanding complete confounder control; arguing for the existence of phantom confounders; arguing that the effect size is trivial; building nonveridical models; arguing for no effect from inadequate sample size; demanding causal proof; arguing that causality is reversed; conducting a ballot of published studies. These are examined in this paper.     

Identification of a GM1-Binding Protein on the Surface of Murine Neuroblastoma Cells

S20Y murine neuroblastoma cells appear to express a protein component(s) able to adhere specifically to the oligosaccharide portion of GM1 (oligo-GM1). To identify proteins with which the oligo-GM1 becomes closely associated, a radiolabeled (125I), photoactivatable derivative of oligo-GM1 was prepared. This was accomplished by reductive amination of the glucosyl moiety of oligo-GM1 to 1-deoxy-1-aminoglucitol, followed by reaction of the amine with sulfosuccinimidyl 2-(p-azidosalicylamido)ethyl-1,3'-dithiopropionate (SASD). Crosslinking studies using the photoactivatable probe indicated that it came in close proximity to a protein with an apparent molecular mass of approximately 71 kDa. In competition experiments, as little as a 10-fold molar excess of oligo-GM1 resulted in a selective reduction in labeling of this protein; preincubation with a 200-fold molar excess of siayllactose was necessary to observe the same change in the labeling pattern, lending additional support to the hypothesis that the approximately 71-kDa protein specifically associates with oligo-GM1. Cell surface location of the oligo-GM1 binding protein was confirmed using subcellular fractionation and morphological analyses.     

Circulating immune complexes in the pathogenesis of recurrent erysipelas

The dynamics of circulating immune complexes (CIC) in comparison with the level of SH-groups of serum deproteinate and other characteristics of cell-mediated and humoral immunity (the reaction of the inhibition of antibodies, the levels of T-cells and their main subpopulations) was studied in 103 erysipelas patients and in 46 persons having had the disease at the acute period of this infection and at the periods between relapses. The elevated levels of CIC and SH-groups of serum deproteinate were found to be directly correlated with the inhibition index. The study showed that, as a rule, in patients with the elevated level of CIC the frequently relapsing form of erysipelas, accompanied by the formation of relative hypersuppressor-type secondary immunodeficiency and by a decrease in the functional activity of dermal macrophages, was observed.     

Some consequences of the covalent and non-covalent binding modes of plasmin with alpha 2-macroglobulin

Analysis of plasmin-alpha 2-macroglobulin interactions by polyacrylamide gel electrophoresis showed that both the light and heavy chains of the proteinase have covalent links with the inhibitor. This covalent binding occurs with a 95 +/- 5% yield and can be abolished in the presence of hydroxylamine without modification of the plasmin-alpha 2-macroglobulin stoichiometry, the extent of the 180-kDa peptide chain cleavage and the generation of the -SH groups. However, these two different binding modes greatly influence the enzymatic properties of the proteinase as well as the occupancy by an other proteinase molecule of the free binding site of the (1:1) plasmin-alpha 2-macroglobulin complex. Non-covalently bound plasmin is more active on synthetic substrates and interacts more tightly with the basic pancreatic trypsin inhibitor than the covalently bound enzyme. Furthermore, the former complex incorporates significantly more chymotrypsin than the latter. The incorporation of chymotrypsin influences the catalytic properties of plasmin within the ternary complex.     

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)     

The study of X-rays and TCDD effects on satellite associations may suggest a simple model for application in environmental mutagenesis

Summary Satellite associations were used as parameters to test nucleolar organizer activity. Assuming that toxic and/or mutagenic agents may affect the ribosomal genes, satellite associations in human lymphocytes were analysed following exposure to X-rays and compared with the satellite association pattern of subjects exposed to TCDD. A significant decrease in the satellite association frequency in D group chromosomes was found both in irradiated lymphocytes and in subjects exposed to Dioxin. The findings seem to be in accordance with the hypothesis based on random damage of functional nucleolar organizing regions.     

Initial Commitment to Pre-Exposure Prophylaxis and Circumcision for HIV Prevention amongst Indian Truck Drivers

Studies of HIV prevention interventions such as pre-exposure prophylaxis (PREP) and circumcision in India are limited. The present study sought to investigate Indian truck-drivers initial commitment to PREP and circumcision utilizing the AIDS Risk Reduction Model. Ninety truck-drivers completed an in-depth qualitative interview and provided a blood sample for HIV and HSV-2 testing. Truck-drivers exhibited low levels of initial commitment towards PREP and even lower for circumcision. However, potential leverage points for increasing commitment were realized in fear of infecting family rather than self, self-perceptions of risk, and for PREP focusing on cultural beliefs towards medication and physicians. Cost was a major barrier to both HIV prevention interventions. Despite these barriers, our findings suggest that the ARRM may be useful in identifying several leverage points that may be used by peers, health care providers and public health field workers to enhance initial commitment to novel HIV prevention interventions in India.     

Hormonal regulation of anabolic processes and of protein utilization efficiency in the early postnatal period

The levels of thyroid, pituitary and steroid hormones-thyroxine, triiodothyronine and 11-hydroxycorticosteroids in the blood serum, somatotropin in the pituitary, and processes of protein assimilation were studied in rats in the early postnatal period. The highest endogenous production of thyroxine, triiodothyronine and somatotropin was detected in 15-day-old rats. The highest level of protein utilization was detected in 7 to 15-day-old rats, followed by the lowering of the utilization on changing over to definitive nutrition. Endogenous production of the anabolic hormones thyroxine, triiodothyronine and somatotropin was found to correlate with a high level of protein utilization in rats within the first days of life after birth.