Outbreak of Salmonella serotype Hartford infections associated with unpasteurized orange juice

CONTEXT: Acidic foods such as orange juice have been thought to be unlikely vehicles of foodborne illness. OBJECTIVE: To investigate an outbreak of Salmonella enterica serotype Hartford (Salmonella Hartford) infections among persons visiting a theme park in Orlando, Fla, in 1995. DESIGN: Review of surveillance data, matched case-control study, laboratory investigation, and environmental studies. SETTING: General community. PARTICIPANTS: The surveillance case definition was Salmonella Hartford or Salmonella serogroup C1 infection in a resident of or a visitor to Orlando in May or June 1995. In the case-control study, case patients were limited to theme park hotel visitors and controls were matched to case patients by age group and hotel check-in date. MAIN OUTCOME MEASURES: Risk factors for infection and source of implicated food. RESULTS: Sixty-two case patients from 21 states were identified. Both Salmonella Hartford and Salmonella enterica serotype Gaminara (Salmonella Gaminara) were isolated from stool samples of 1 ill person. Thirty-two case patients and 83 controls were enrolled in the case-control study. Ninety-seven percent of case patients had drunk orange juice in the theme park vs 54% of controls (matched odds ratio, undefined; 95% confidence interval, 5.2 to undefined). The orange juice was unpasteurized and locally produced. Salmonella Gaminara was isolated from 10 of 12 containers of orange juice produced during May and July, indicating ongoing contamination of juice probably because of inadequately sanitized processing equipment. CONCLUSIONS: Unpasteurized orange juice caused an outbreak of salmonellosis in a large Florida theme park. All orange juice was recalled and the processing plant closed. Pasteurization or other equally effective risk-management strategies should be used in the production of all juices.     

Thermostable archaeal O6-alkylguanine-DNA alkyltransferases

Archaea represent some of the most ancient organisms on earth, and they have relatively uncharacterized DNA repair processes. We now show, using an in vitro assay, that extracts of two Crenarchaeota (Sulfolobus acidocaldarius and Pyrobaculum islandicum) and two Euryarchaeota (Pyrococcus furiosus and Thermococcus litoralis) contain the DNA repair protein O6-alkylguanine-DNA alkyltransferase (ATase). The ATase activities found in the archaea were extremely thermostable, with half-lives at 80 degreesC ranging from 0.5 hr (S. acidocaldarius) to 13 hr (T. litoralis). The temperature optima of the four proteins ranged from approximately 75 to approximately 100 degreesC, although activity was seen at 37 degreesC, the temperature optimum of the Escherichia coli and human ATases. In all cases, preincubaton of extracts with a short oligonucleotide containing a single O6-methylguanine residue caused essentially complete loss of ATase activity, suggesting that the alkylphosphotriester-DNA alkyltransferase activity seen in some prokaryotes is not present in Archaea. The ATase from Pyrobaculum islandicum had an apparent molecular mass of 15 kDa, making it the smallest of these proteins so far described. In higher organisms, ATase is responsible for the repair of toxic and mutagenic O6-alkylguanine lesions in alkylated DNA. The presence of ATase in these primitive organisms therefore suggests that endogenous or exogenous exposure to agents that generate appropriate substrates in DNA may be an early event in evolution.     

Relationships between cell density, glutathione and proliferation of A549 human lung adenocarcinoma cells treated with acrolein

Acrolein is a highly electrophilic alpha,beta-unsaturated aldehyde to which humans are exposed in various situations. Acrolein reacts rapidly with and depletes cellular glutathione (GSH), and is toxic to various types of cells. In the current study, the ability of acrolein to alter proliferation of A549 cells was found to be dependent on cell density as well as total cell number. Thus, 'doses' must be expressed per cell rather than as a concentration, and all related studies need to be performed by plating a constant number of cells. A549 cells were plated at various densities and treated with acrolein after 48 h. Acrolein doses up to 47 fmol/cell at the time of treatment did not cause cell lethality. However, growth of A549 cells (as shown by thymidine incorporation, alamarBlue and total protein) was inhibited at acrolein levels > 34 fmol/cell in 6-well plates seeded at 5000 cells/cm2 48 h prior to treatment. Cellular GSH levels were decreased 34% by 2 h at acrolein levels of 6.7 fmol/cell and by 65% at 47 fmol/cell. Recovery of GSH was rapid at 6.7-47 fmol/cell acrolein, returning to control levels or above by 12 h post-treatment. These data show a strong correlation between cellular GSH and proliferation. The apparent conflict with a previous study of Ramu et al., suggesting that sublethal concentrations (up to 10 microM) of acrolein inhibited the proliferation of A549 cells without a decline in total cellular GSH, arose because, while the acrolein concentration was the same in cells used for proliferation and GSH assays, GSH measurements were done in cells plated at a higher density, resulting in a much lower acrolein dose per cell. Interestingly, very low dose levels of acrolein with cells seeded at low densities stimulated cell growth despite an initial decline in GSH content. Preliminary studies with the stress genes hsp70 and gadd153 suggest that acrolein at 35 fmol/cell does not stimulate formation of their mRNA beyond the level stimulated by a 2 h incubation in serum-free medium but may actually delay or decrease the induced expression. The mechanism(s) of the inhibitory and mitogenic effects of acrolein remains to be determined, but could be due to changes in gene expression induced by this electrophile, perhaps mediated by changes in GSH.     

Formal home care services: examining the long-term care needs of rural older women

Trauma is the leading cause of death in people less than 40 years old (Central Statistics Office, 1994). Patients who have sustained major trauma will often have multiple injuries. The key to treating these patients is an organized and systematic method of examination and treatment to ensure that injuries are not missed and left untreated.     

A multimedia interhospital communications system for medicalconsultations

The authors present a study whose main objective has been to explore the use of high-bandwidth multimedia communications technology for medical applications physically distributed among hospitals, that is to say an interhospital multimedia communications system. The design and development issues of a prototype are described, as well as the results of an in-field trial. From the results of this trial, a performance study has been developed for evaluating the expected communications requirements of a large-scale configuration of the system     

Isolation and biological characterization of Legionella pneumophila mutants resistant to aminoglycoside antibotics and their protective action]

Preliminary estimation of virulence in some antibiotic resistant mutants of Legionella pneumophila, Philadelphia 1 in various models of infection revealed its decrease in the mutants resistant to azlocillin, cefotaxime, fluoroquinolone LIB-80, neamine and streptomycin. Detailed investigation of the neamine resistant mutants showed that in relation to streptomycin susceptibility such mutants could be divided into 3 classes: susceptible to streptomycin, resistant to high concentrations of streptomycin and resistant to moderate concentrations of streptomycin. Part of mutants Nea(r)Strr and Nea(r)Strr500 and all mutants Nea(r)Strr100 proved to be less virulent with respect to guinea pigs and chick embryos. The study of the spectinomycin resistant mutants of Legionella spp. did not reveal any changes in the virulence which made it possible to suggest that the influence of the mutations in the ribosomal protein genes determining resistance to streptomycin and neamine on virulence of L. pneumophila was based on the interdependence of the mutant effect on the suppression and the influence on the virulence detected by us in S. flexneri, Y. pseudotuberculosis, L. monocytogenes and F. tularensis. The Legionella mutants Nea(r)Strr100 were characterized by significant protective activity and protected immunized guinea pigs when tested in a model of their aerogenic infection.     

Inhibition of potassium (KATP) channels reduces the short-circuit current response of rat colonic mucosa to acetylcholine

Intestinal secretion depends upon electrogenic chloride transport into the gut lumen, which requires maintenance of an electrically negative cell-membrane voltage. We have investigated whether secretory responses of rat colonic mucosa to acetylcholine were sensitive to inhibition of potassium channels and whether selective inhibition could indicate the nature of the channel involved. Rat colonic mucosa was set up in Ussing chambers, short-circuit current responses obtained to acetylcholine, and the sensitivity of such responses to inhibition of potassium channels was investigated. Non-selective potassium-channel blockade by barium induced concentration-dependent inhibition of responses to acetylcholine. Similar inhibitory effects were obtained using 4-aminopyridine and glibenclamide. 5-Hydroxydecanoate and phentolamine also inhibited the increase in short-circuit current. However, a combination of charybdotoxin plus apamin was without effect. We conclude that a basolateral outward movement of potassium ions is required for the secretory action of acetylcholine on rat colonic mucosa. The potassium channel involved seems to be ATP-dependent and calcium-insensitive.     

Characterization of a human papillomavirus type 16 variant-dependent neutralizing epitope

We have determined that three type-specific and conformationally dependent monoclonal antibodies, H16.E70, H16.U4, and H16.V5, neutralize pseudotype human papillomavirus type 16 (HPV16) virions in vitro. H16.U4 and H16.V5 neutralized pseudotype virions derived from the German HPV16 variant 114K and the Zairian variant Z-1194 with equal efficiency. In contrast, neutralization of Z-1194 pseudotype virions by H16.E70 was two orders of magnitude weaker than neutralization of 114K pseudotype virions. This difference correlated with enzyme-linked immunosorbent assay reactivity of H16.E70 to L1 virus-like particles of the two variants. A substitution at residue 282 of L1 was responsible for this differential reactivity, suggesting that this residue constitutes part of the H16.E70 epitope.     

Dormant forms of Yersinia pseudotuberculosis during interaction with green algae and their exometabolites (population dynamics and ultrastructure)

The dynamics of the transition of Y.pseudotuberculosis to the latent (noncultivable) state in sterile soil extraction and in soil extraction, containing Scenedesmus algae or their exometabolites, was evaluated by the bacteriological method and with the use of polymerase chain reaction. The formation of Y.pseudotuberculosis latent forms achieved its highest rate under the action of algal exometabolites (on day 11), while in the presence of algal cells such formation was delayed to 3-5 months. The partial reversion of Y.pseudotuberculosis nonculativable forms to vegetative, bacteriologically detectable forms occurred under the action of fetal serum, as well as live or killed infusoria. Transmission electron microscopy demonstrated that noncultivable Y.pseudotuberculosis had a round form, diminished cell size, denser cytoplasm and enlarged cytoplasmic space. The reversible transition of bacteria to the latent state is regarded as their adaptation to unfavorable factors during their existence in soils and water reservoirs.     

Genotypic basis of low viability in vestigial mutants of Drosophila melanogaster

The role of a marker mutation and other genes in a decrease in viability was studied in the Drosophila melanogaster vg line. In flies of the C-S line, chromosome 2 was substituted by the homologous chromosome of the vg flies. In addition, the flies of the mutant phenotype with mutant genes partially or completely substituted by the wild-type C-S genes were obtained in saturating crosses C-S x vg. In the reciprocal variant of chromosome 2 substitution, the flies of the C-S phenotype with chromosomes 1, 3, and 4 from the vg line were obtained. Chromosome 2 of the vg line, introduced into C-S fly karyotype, proved to substantially reduce the heat resistance and life span of flies. In the case of reciprocal replacement (C-S line chromosome 2 substituted for the homologous chromosome of vg flies), a significant increase in viability was observed, which, however, never reached the level characteristic of the C-S line. As the vg genotype became saturated with C-S genes, the heat resistance and life span of flies increased substantially. However, even the complete saturation of mutant chromosomes with wild-type genes never resulted in the equal viability of vg and C-S flies. These data suggest that the low viability of the vg mutant is largely accounted for by the gene composition of the second chromosome and, primarily, by the presence of the vg gene. Nevertheless, there is evidence that, along with the pleiotropic effect of the marker mutation, other genes not linked to chromosome 2 are responsible for the studied physiological properties of the vg flies.