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The usefulness of risk assessment is limited by its ability or inability to model and evaluate risk uncertainty and variability separately. A key factor of variability and uncertainty in microbial risk assessment could be growth variability between strains and growth model parameter uncertainty. In this paper, we propose a Bayesian procedure for growth parameter estimation which makes it possible to separate these two components by means of hyperparameters. This model incorporates in a single step the logistic equation with delay as a primary growth model and the cardinal temperature equation as a secondary growth model. The estimation of Listeria monocytogenes growth parameters in milk using literature data is proposed as a detailed application. While this model should be applied on genuine data, it is highlighted that the proposed approach may be convenient for estimating the variability and uncertainty of growth parameters separately, using a complete predictive microbiology model.

The overgrowth of Listeria innocua in enrichment broths designed for the isolation of Listeria monocytogenes is believed to result from two factors: a selective growth advantage of L. innocua, and/or an inhibitory interspecies interaction. The generation times of 13 isolates of L. innocua and L. monocytogenes were determined in Brain Heart Infusion (BHI) and a variety of enrichment media. No significant differences were found in growth characteristics between either species in the various media, suggesting that the growth advantage of L. innocua in enrichment media was not as significant as previously described. Kinetic analysis of mixed cultures of L. monocytogenes and isolates of L. innocua producing a variety of inhibitory activities demonstrated the possibility of an inhibitory interaction between these two species resulting in the overgrowth of the enrichment culture with L. innocua. Modelling the evolution of the ratio between two populations in an enrichment process was used to analyze the impact of a selective growth advantage in L. innocua in an enrichment process for growth of L. monocytogenes. These findings support the widely held view that an overgrowth of L. innocua in the enrichment process can result from both a selective growth advantage as well as the production of inhibitory compounds. From a practical perspective, these interactions can result in an increase in false negatives.

Splanchnic hypoperfusion, with pathogenic implications for multiple organ failure, can occur during septic shock. We report four patients with septic shock in whom regional hepatosplenic splanchnic perfusion was monitored through suprahepatic vein catheterization and gastric tonometry. Suprahepatic lactate and oxygen saturation showed splanchnic hypoperfusion in all patients. These parameters improved only in the patient that survived. Gastric tonometry was more inconsistent. We conclude that suprahepatic vein catheterization could have a role in the management of septic shock.

Since 1991, new epidemic methicillin-resistant Staphylococcus aureus (MRSA) strains characterized by the unexpected reappearance of heterogeneous phenotypic expression of resistance to methicillin and by susceptibility to gentamicin and various other antibiotics (GS-MRSA) have been reported in France. GS-MRSA strains have progressively replaced MRSA clones expressing homogeneous resistance to methicillin and resistance to gentamicin (GR-MRSA). In this study, we investigated the physiological characteristics of these new clones. In particular, we evaluated and compared the maximal growth rate and the deduced generation times (related to fitness of strains) of the major French epidemic MRSA clones. The population studied consisted of 79 isolates including (i) GR-MRSA that comprised six different types on the basis of PFGE; (ii) GS-MRSA the majority of which clustered into two PFGE types, A1 (usually resistant to erythromycin) and B (usually susceptible to erythromycin); (iii) methicillin-susceptible S. aureus (MSSA). GS-MRSA-A1 and MSSA strains were shown to have a significant fitness benefit (about 20%) with shorter generation times (theta = 23.7 +/- 0.1 and 22.9 +/- 0.05 min, respectively) than GR-MRSA and GS-MRSA-B strains (theta = 30.3 +/- 0.2 and 32.5 +/- 0.5 min, respectively). These data suggest that a link exists between genetic patterns, resistance profiles and physiological properties. In vitro competitive experiments indicated that GS-MRSA- A1 strains were able to rapidly outgrow GR-MRSA strains. The growth advantage observed should be taken into account in understanding the spread of some new clones of MRSA.

Modeling of batch kinetics in minimal synthetic medium was used to characterize Escherichia coli O157:H7 growth, which appeared to be different from the exponential growth expected in minimal synthetic medium and observed for E. coli K-12. The turbidimetric kinetics of 14 of the 15 O157:H7 strains tested (93%) were nonexponential, whereas 25 of the 36 other E. coli strains tested (70%) exhibited exponential kinetics. Moreover, the anomaly was almost corrected when the minimal medium was supplemented with methionine. These observations were confirmed with two reference strains by using plate count monitoring. In mixed cultures, E. coli K-12 had a positive effect on E. coli O157:H7 and corrected its growth anomaly. This demonstrated that commensalism occurred, as the growth curve for E. coli K-12 was not affected. The interaction could be explained by an exchange of methionine, as the effect of E. coli K-12 on E. coli O157:H7 appeared to be similar to the effect of methionine.

Identification of the proximate peroxisome proliferator(s) derived from di (2-ethylhexyl) adipate (DEHA) has been achieved using primary hepatocyte cultures derived from different species and cyanide-insensitive fatty acyl CoA oxidase (PCO) as a marker enzyme for peroxisome proliferation. In rat and mouse hepatocytes, the parent compound (DEHA) had no effect on peroxisomal beta-oxidation, but primary metabolites of DEHA, mono (2-ethylhexyl) adipate (MEHA) and 2-ethylhexanol (EH), were approximately equipotent in PCO induction (5-fold at 0.5 mM final concentration). The secondary metabolite of DEHA, 2-ethylhexanoic acid (EHA), was in both species the most potent peroxisome proliferator (25- and 9-fold induction in mice and rats, respectively, at 1 mM final concentration). At 2 mM final concentration a tertiary metabolite of DEHA, 2-ethyl-5-hydroxyhexan-1-oic acid, was less effective in mouse and rat hepatocytes at inducing PCO (15- and 5-fold, respectively). 2-Ethyl-5-oxohexan-1-oic acid and 2-ethylhexan-1,6-dioic acid had little effect (2-3-fold in both rat and mouse hepatocytes). Thus, EHA was identified as the proximate peroxisome proliferator of DEHA and mouse hepatocytes were approximately twice as sensitive as rat hepatocytes to peroxisome proliferation due to MEHA, EH and EHA. We investigated further species differences in response to peroxisome proliferators by using guinea pig and marmoset primary hepatocyte culture. None of the chemicals studied stimulated peroxisomal beta-oxidation in these species up to a final concentration of 2 mM. Higher concentrations lead to cytotoxicity. This lack of sensitivity of guinea pig and marmoset hepatocytes is in agreement with previous studies with di (2-ethylhexyl) phthalate metabolites, suggesting the absence of a threat of hepatocarcinogenic damage to these species and confirming that primary hepatocytes cultures are useful models for investigating the phenomenon of peroxisome proliferation.

The dose-response relationships for peroxisome proliferation due to Di (2-ethylhexyl) adipate (DEHA), 2-ethylhexanol (EH), 2-ethylhexanoic acid (EHA) have been investigated in rats and mice. Linear dose-response relationships were observed for induction of cyanide-insensitive palmitoyl CoA oxidation (PCO), used as a enzyme marker of peroxisome proliferation, by DEHA, EH and EHA in both species. Relative liver weights were also increased in a dose related manner. On a molar basis, DEHA was twice as potent as EH or EHA which were equipotent and PCO was stimulated to a greater extent in male mice than in rats or female mice. At doses above 8 mmol/kg/day, EH was toxic to rats (both sexes) and similarly EHA at 13.5 mmol/kg/day lead to the death of female rats. In a attempt to explain the species difference in carcinogenicity of DEHA previously reported, we also used Fischer 344 rats and B6C3F1 mice. DEHA administration (2.5 g/kg/day) to Fischer 344 rats and B6C3F1 mice lead to toxicity in female rats. Relative liver weights were increased in a dose related fashion by DEHA administration to both rats and mice, PCO but not catalase was markedly increased (up to 15 fold in male rats). Light microscopy examination indicated some glycogen loss, a dose related hypertrophy and increased eosinophilia in both rats and mice. Electron microscopy confirmed peroxisome proliferation accompanied by a marked reduction of lipid in the centrilobular hepatocytes. These data suggest EHA to be the proximate peroxisome proliferator derived from DEHA.(ABSTRACT TRUNCATED AT 250 WORDS)

In terms of parasitaemia in blood, the prevalence was 18.7% for Plasmodium falciparum, 10.5% for P. ovale and 1% for P. malariae in the villages of Mungo Ndor and Kokobuma. The plasmodial index of children from 2 to 9 years of age was 38.2% and the spleen index 26.6%, with a mean HACKETT score of 1.56. Malaria is thus meso-endemic in the region. The immunofluorescent test performed with a P. falciparum antigen was positive in 66% of the children in the same age group. Parasites were seen in 15% of new-born children. The malaria infection indices were higher in Mungo Ndor, which is located on the main road in the vicinity of the Manyemen hospital, than in Kokobuma. Morbidity and mortality due to malaria remain major problems in this part of the South-West Province, in spite of improving primary health care facilities and free chloroquine distribution. Anopheles gambiae is the main vector of malaria in the area, and transmission is interrupted only during the short dry season.

In conclusion we know human and animal gathering is usually required for the development of water invertebrate populations, and particularly Bulinus contortus or Culicidae larvae, in a water system polluted with excrements or sewage. Such conditions are not those of Hassan Addakhil lake and the latter is not to-day, on its surface, a source of contamination. As we report p. 486, the study of an eventual increase of malaria and bilharzia endemia due to new aval more or less distant irrigations, belongs to the control of the Hygiene Institute of Morocco and collaborators of physicians of the Tafilalet province. This item will be discussed later on.

We examined sensitive biochemical and immunological markers of kidney function and damage in 53 male oil refinery workers exposed to hydrocarbons and compared their results with those of a control group of 61 age-matched nonexposed males. The mean duration of employment of exposed males was 11 years. The current levels of exposure to a variety of aliphatic and aromatic hydrocarbons, as determined by personal monitoring, were well below the current threshold limit values. No difference was found in the urinary tubular parameters beta-N-acetyl-D-glucosaminidase, beta 2-microglobulin (beta 2-m) and retinol-binding protein. Similar serum beta 2-m levels indicated no impairment of the glomerular filtration rate in the exposed workers. The levels of circulating immune complexes were also identical in both groups. The mean albuminuria was slightly higher (p less than .005) in the exposed group in a quantitative assay but was not dipstick-detectable. The mean urinary excretion of a renal antigen was also higher (p less than .05) in the exposed group and correlated with the excretion of albumin. Finally, slightly higher titers of anti-laminin antibodies were found in five exposed employees, but this was not accompanied by an increased albuminuria. We conclude that chronic low-level hydrocarbon exposure in these refinery workers does not lead to clinically significant renal abnormalities. Nevertheless, some findings are consistent with the possible role of hydrocarbon exposure in the induction of renal disturbances.

The cellular material studied in the urinary sediment mainly obtained from exfolied alls the bladder trigone was submitted to hormonal stimulation. These cell changes constitute the basis of a cytologic method called the urocytogram. The urocytogram was followed up in six children with early puberty and ten young girls with backward puberty. These repeated examinations contribute to the diagnosis and help in the differential diagnosis. Whenever it is necessary to investigate a child' sex hormones the urocytogram, simple painless method is indicated.

The cellular material studied in the urinary sediment mainly obtained from exfoliated cells of the bladder trigone was submitted to hormonal stimulation. The urocytogram has proved a useful and even necessary examination to establish the hormonal check-up of a child suffering from early puberty. This simple, painless method, without any psychological consequences is also indicated in pediatric gynecology, and in certain sexual ambiguity cases. This examination, undergone by a child premature or not, contributes to the early diagnosis of congenital adrenal hyperplasia. In the course of childhood, it helps to investigate pseudohermaphroditisms and various malformations. This examination has proved an important help in the diagnosis of all the cases of sexual ambiguity.

A software package of general interest, and adapted to the analysis of histological sections has been written. The different programs of this package have been classified into four groups: macroanalysis, selection of fields, analysis, and data processing. The macroanalysis allows the acquisition of topographical information that will be used during the selection of fields and the analysis. Mapping programs have been added to the classical data processing of the measured parameters (statistical calculations, edition of values, histograms, graphs, .. .). They allow the generation of parametric images representing the distribution of particular elements in the section, or the topographical variations of calculated parameters. The recombination of information obtained at different magnifications, and the correlation of information of different types is thus possible and of great interest in the study of complex histological structures.