Effect of sodium chloride on transport of bacteria in a saturated aquifer material

Determinations were made of the influence of NaCl concentration, cell density, and flow velocity on the transport of Pseudomonas sp. strain KL2 through columns of aquifer sand under saturated conditions. A pulse-type boundary condition was used. The experiments were conducted by using 0.3-m-long Plexiglas columns with an internal diameter of 0.05 m. When a 1-h pulse of a 0.01 M NaCl solution containing 10(8) cells per ml was added at a flow rate of 10(-4) m s-1, the bacterial density in the effluent never exceeded 2.2% of the density of cells added, and only 1.5% of the bacteria passed through the aquifer material. In contrast, when the bacteria were applied in distilled water, the relative cell density in the effluent approached 100%, and 60% of the bacteria were transported through the aquifer solids. Under these conditions, the breakthrough of Pseudomonas sp. strain KL2 was slower than chloride. When the flow rate was 2.0 x 10(-4) m s-1, the cell density in the effluent reached 7.3% of that added in 0.01 M NaCl solution, but only 3.9% of the bacteria were transported through the aquifer particles. On the other hand, the density in the effluent approached 100% of that added in deionized water, and 77% of the added bacteria were recovered. When the density of added cells was 10(9) cells per ml at a flow rate of 10(-4) m s-1, the densities in the effluent reached 70 and 100% of those added in salt solution and deionized water, respectively, and 44 and 57% of the bacteria were transported through the aquifer solids.(ABSTRACT TRUNCATED AT 250 WORDS)

Environmental mutagens that induce the adaptive response to alkylating agents in Escherichia coli

Many microorganisms exhibit an adaptive response to mutagenic alkylation damage. In Escherichia coli the response is regulated by the inducible Ada protein. A sensitive immunoassay employing two anti-Ada monoclonal antibodies has been developed here to monitor low levels of induction of the Ada protein. This protein was detected in non-induced E. coli which contained an average of two molecules of Ada per cell. The occurrence of the adaptive response in bacteria signals the existence of an ecological niche in which cells are exposed to direct-acting methylating compounds, but the structure and identity of these agents are unknown. Using the immunoassay to search for possible candidates, a number of methylating agents and precursors of such agents have been investigated. Carbamyl phosphate and methylamine yield N-methylurea, which reacts subsequently with nitrite to generate the strong inducer N-methyl-N-nitrosourea. The antibiotic streptozotocin also is a potent inducer of the adaptive response. Moreover, the abundant environmental mutagen methyl chloride acts as an inducer.

Genetic and immunochemical analysis of mutant p53 in human breast cancer cell lines

The expression of the tumour suppressor gene p53 was analysed in 11 human breast cancer cell lines by immunohistochemistry, immunoprecipitation and cDNA sequencing. We used a panel of anti-p53 monoclonal antibodies for cell staining and found abnormalities in every case. Eight of the cell lines produce a form of p53 which can be immunoprecipitated by the monoclonal antibody PAb240 but not by PAb1620. In the murine system PAb240 only immunoprecipitates mutant p53. We sequenced p53 cDNA directly from four of the PAb240 positive cell lines using asymmetric PCR templates. All four contained missense mutations in p53 RNA, with no detectable expression of the wild type sequence. Different residues were affected in each cell line, but all the mutations changed amino acids conserved from man to Xenopus. These results imply that as in the murine system, the PAb240 antibody reliably detects a wide variety of p53 mutations and that these mutations have a common effect on the structure of p53. Immunohistochemical data suggest that p53 mutation is the commonest genetic alteration so far detected in primary breast cancer.

A data-based approach to diet questionnaire design and testing

A self-administered diet history questionnaire has been developed for epidemiologic and clinical use. Both the food list and the nutrient values to be associated with it were developed using dietary data from 11,658 adult respondents to the Second National Health and Nutrition Examination Survey (NHANES II). Food items were selected on the basis of their contribution to total population intake of energy and each of 17 nutrients in the NHANES II data, and represent over 90% of each of those nutrients. Associated nutrient composition values were determined from the NHANES II database using frequency of consumption data in that survey. Portion sizes to be associated with each food item were derived from observed portion size distributions in NHANES II, based on three-dimensional models. The resulting food list and its corresponding brief data base, when used to calculate nutrients from a diet record, yielded correlations of r greater than 0.70 with the more detailed method. Field administration produced mean values comparable to national data.

Cellular targets for SV40 large T-antigen

SV40 virus infection is able to induce tumours in newborn hamsters and to transform a wide range of eukaryotic cells in in vitro culture. This is achieved by integration of the viral DNA into the host cell DNA and expression of the virus-encoded Large T-antigen. The expression of Large T, a 708 amino acid phosphoprotein, is required both to induce and maintain the transformed state. The Large T protein initiates viral DNA synthesis and regulates viral transcription, apparently by binding in a specific manner to viral DNA sequences at and near the viral origin of replication. SV40 Large T also affects cellular DNA synthesis and transcription and this may account for its oncogenic activity. A novel immunochemical procedure has permitted the isolation of cellular DNA sequences occupied by SV40 Large T in the chromatin of SV40 transformed cells. Some of the cellular sequences contain high affinity binding sites for SV40 Large T, and hybridize to messenger RNAs expressed in SV40 transformed but not in normal cells. A second type of cellular target for Large T is the cell coded p53 protein that it binds to and stabilizes. A range of monoclonal antibodies to p53 has been isolated and characterized. They demonstrate that p53 is in the cytoplasm of normal cells but is located in the nucleus of transformed cells. One of the antibodies recognizes an epitope on p53 that is stabilized or induced by binding to Large T. Further studies on the T-p53 protein complex have been facilitated by constructing bacterial plasmids that direct the synthesis of substantial quantities of Large T-beta-galactosidase and p53-beta-galactosidase fusion proteins in bacteria. The results are discussed in the context of our current knowledge of oncogene action.

Secondary infection of rat lungs with Pasteurella pneumotropica after Kilham rat virus infection

Lung congestion was observed after an outbreak of Kilham rat virus infection (KRV) in a rat colony, previously free of all rat viruses. A high proportion of congested lungs contained Pasteurella pneumotropica suggesting that KRV might have caused primary damage to the alveoli (hitherto not recorded) which allowed the secondary bacterial colonization. Experimental infection of rats with KRV caused acute damage to the lung alveoli. Since KRV infection is very common in animal facilities it could therefore be a significant agent in the development of respiratory disease.

Comparison of alkaline phosphatase and horseradish peroxidase conjugated antisera in the ELISA test for antibodies to reovirus 3, mouse hepatitis and Sendai viruses

The method of enzyme-linked immunoadsorbent assay (ELISA) has been applied to the detection of antibodies to reovirus 3, Sendai virus and mouse hepatitis virus (type 1), and the serological response of mice after infection has been followed for 28 days to investigate the earliest appearance of ELISA titres. This has been compared to the appearance of haemagglutination-inhibiting and complement-fixing antibodies.

Alkaline phosphatase conjugated antiserum produces the most sensitive and convenient ELISA for the murine viruses examined.

Prevalence of indigenous viruses in laboratory animal colonies in the United Kingdom 1978-1979

Compared with the results of the previous serological survey of 1976-1977, it can be seen that mouse hepatitis virus is still prevalent in the mouse colonies and that corona viruses of rats are also common. The prevalence of Sendai virus has increased considerably. However, the prevalence of Reo 3 virus appeared to have decreased, although this may be the results of the different test used.

The course of infection of Encephalitozoon cuniculi in immunodeficient and immunocompetent mice

A humoral and cellular response was detected in C57BL mice 14-21 days after experimental infection with Encephalitozoon cuniculi. In athymic (nu/nu) mice a severely limited cellular response and no antibodies were detected, but masses of spores were found in the liver and other viscera. These spores were probably responsible for the death of the nude mice. Antibodies in C57BL mice remained at high levels for at least 17 months after infection.

A survey of Encephalitozoon cuniculi in laboratory animal colonies in the United Kingdom

Of 38 animal colonies serologically examined for Encephalitozoon cuniculi, 1 mouse, 2 rat and 4 guineapig colonies were positive. A further survey showed that the prevalence within mouse, rat, guineapig and rabbit colonies varied between 25 and 95%. Guineapigs housed with infected rabbits are at a greater risk of being infected than those housed separately. Nephritis was a common feature, but cerebral granulomata were not seen.

Investigation into the transplacental transmission of Encephalitozoon cuniculi in rabbits

An investigation into the transmission of Encephalitozoon cuniculi was undertaken in both naturally- and experimentally-infected rabbits. Only 2 nurslings were found with rising antibody titres at 8-10 weeks of age, when infection could have been caused by environmental contamination.

Clinical aspects of continuous neonatal oxygen monitoring

Twenty newborn infants (gestational age 30--40 weeks, weight 980--3400 g) were studied in two groups to compare two commercially available systems for continuous in vivo oxygen monitoring: the So2 catheter and the transcutaneous Po2 (TcPo2) electrode, and their respective electronic systems. Measurements from these systems were correlated with determinations made from samples intermittently drawn and measured by conventional So2 and Pao2 in vitro methods , respectively. Information about these two in vivo oxygen monitoring systems was then related to our previous experience with the bare-wire earlobe O2a electrode. Measurements from the two in vivo monitoring techniques studied showed good correlations with their respective in vitro oxygen measurements: So2 catheter, y = x - 3.08, r = 0.98 (range studied 74% to 100%) and transcutaneous electrode, y = 0.98x + 0.57, r = 0.89 (range studied 34 to 92 mm Hg). It was concluded that all three systems give a good reflection of central arterial oxygen (either Sao2 or Pao2)). The system to be used in specific clinical situations should depend on condition of the baby and stage of treatment, need for an umbilical line to measure other variables, equipment available, and training of personnel.

The immunoperoxidase test diagnosis of Encephalitozoon cuniculi in rabbits

Sera collected from both naturally and artificially infected rabbits were found to show excellent correlation when examined for the presence of Encephalitozoon cuniculi antibodies using the immunoperoxidase and immunofluorescence tests. Out of 85 randomly selected rabbits, 21 were found to be serologically positive using both the tests. However, lesions which could be attributed to E. cuniculi infection were only demonstrated in 16.