Pathogenesis, growth and survival characteristics of Listeria monocytogenes - a newly emerged food-borne pathogen

A research article on some newly discovered pathogens that are found in food items.Survival and growth characteristics of Listeria monocytogenes isolates were determined in Tryptose Phosphate Broth and in chicken and beef substrates in the period 1993 to 1994. Observed generation times for the Scott A strain (clinical isolate) in Tryptose Phosphate Broth, anaerobically, were 146.2,21.0,16.5,8.2 and 1.6 hours at 0,3.5,5.5, 8.0 and 20°C, respectively, compared to 123.4,23.1,17.5,7.5 and 1.5 hours, aerobically. Similar growth rates were observed for strain RMIT 405 (raw chicken isolate), both anaerobically and aerobically in Tryptose Phosphate Broth, chicken and beef substrates. Growth rates were fitted to the square root model with a coefficient of determination (R2 value) of 98.36 to 99.48 percent. Heating to an internal temperature of 70°C resulted in a 3 to 5 log reduction of all L. monocytogenes isolates under study in broth and chicken substrates while a heat treatment to 70°C/2 minutes resulted in a reduction greater than 7 log cycles. Lowering the product pH to 5.0 was effective in inhibiting L. monocytogenes growth, whereas a sodium chloride concentration of 2 percent had a negligible effect on growth rates

Infant growth and body composition from birth to 24 months: Are infants developing the same?

Background: Given the importance of infancy for establishing growth trajectories, with later-life health consequences, we investigated longitudinal body composition among infants from six economically and ethnically diverse countries.Methods: We recruited mother-infant dyads using the WHO Multicenter Growth Reference Study criteria. We measured fat-free mass (FFM) in 1393 (49% female) infants from birth to 6 months of age (Australia, India, and South Africa; n = 468), 3-24 months of age (Brazil, Pakistan, South Africa, and Sri Lanka; n = 925), and derived fat mass (FM), fat mass index (FMI), and fat-free mass index (FFMI). Height-for-age (HAZ), weight-for-age (WAZ), and weight-for-length (WHZ) Z-scores were computed. Sex differences were assessed using a t-test, and country differences using a one-way analysis of covariance. We further compared subsamples of children with average (-0.25 \u3e HAZ \u3c +0.25), below-average (≤-0.25) and above-average (≥+0.25) HAZ.Results: HAZ performed well between 0 and 6 months, but less so between 3 and 24 months. The stunting prevalence peaked at 10.3% for boys and 7.8% for girls, at 24 months. By 24 months, girls had greater FMI (10%) than boys. There were significant differences in FFM (both sexes in all countries) and FM (Brazilian boys, Pakistani and South African girls) by 24 months of age between infants with average, above-average, and below-average HAZ.Conclusion: In a multi-country sample representing more ideal maternal conditions, body composition was heterogeneous even among infants who exhibited ideal length. Having a mean HAZ close to the median of the WHO standard for length reduced FFM between-country heterogeneity but not FM, suggesting that other factors may influence adiposity

Stunting in infancy, pubertal trajectories and adult body composition: the Birth to Twenty Plus cohort, South Africa.

BACKGROUND/OBJECTIVES: Childhood rapid growth and earlier puberty onset have been associated with adult obesity. However, the association between childhood stunting, pubertal timing and adult obesity is unclear. We examined whether the relationship between stunting at age 2 years (y) and body composition at 23 years is mediated by adolescent body mass index, and pubertal development, using the Birth-to-Twenty Plus cohort (South Africa). SUBJECTS/METHODS: For 1036 participants, data on anthropometrics between birth and 23 years, maternal factors, and pubertal development (Tanner scale at 9-16 years) were collected. Stunting at 2 years (height-for-age z-score < -2), 5-18 years BMI-for-age trajectories, pubertal development trajectories, and DXA-derived fat mass (FM) and fat free mass (FFM) at 23 years were determined. Data were analysed using hierarchical regressions and structural equation models. RESULTS: Stunting was directly associated with slower pubertal development and with shorter adult stature, but was not associated with adolescent BMI trajectories, adult FM or FFM. However, stunting was indirectly associated with adult FM and FFM through the direct associations between slower pubertal development and lower FM and between shorter height and lower FFM. BMI trajectories were independently associated with FM and FFM. CONCLUSIONS: Being stunted in this population predicted adult body composition through slower pubertal development and shorter adult stature

Functional and molecular interactions between ERK and CHK2 in diffuse large B-cell lymphoma

Distinct oncogenic signalling cascades have been associated with non-Hodgkin lymphoma. ERK1/2 signalling elicits both transcriptional and post-transcriptional effects through phosphorylation of numerous substrates. Here we report a novel molecular relationship between ERK1/2 and CHK2, a protein kinase that is a key mediator of the DNA damage checkpoint that responds to DNA double-strand breaks. Our studies are the first to demonstrate the co-localization and overexpression of ERK1/2 and CHK2 in diffuse large B-cell lymphoma (DLBCL). The physical interaction between ERK and CHK2 was highly dependent on phosphorylated Thr 68 of CHK2. Concurrent administration of an ERK inhibitor enhances the antitumour activity of CHK2 inhibition in both a human DLBCL xenograft model as well as primary human DLBCL cells. Our data suggest a functional interaction between ERK and CHK2 and support the potential combined therapeutic targeting of ERK and CHK2 in human DLBCL

P130Cas Attenuates Epidermal Growth Factor (EGF) Receptor Internalization by Modulating EGF-Triggered Dynamin Phosphorylation

BACKGROUND: Endocytosis controls localization-specific signal transduction via epidermal growth factor receptor (EGFR), as well as downregulation of that receptor. Extracellular matrix (ECM)-integrin coupling induces formation of macromolecular complexes that include EGFR, integrin, Src kinase and p130Cas, resulting in EGFR activation. In addition, cell adhesion to ECM increases EGFR localization at the cell surface and reduces EGFR internalization. The molecular mechanisms involved are not yet well understood. METHODOLOGY/PRINCIPAL FINDINGS: We investigated the molecular mechanism by which p130Cas affects the endocytic regulation of EGFR. Biochemical quantification revealed that cell adhesion to fibronectin (FN) increases total EGFR levels and its phosphorylation, and that p130Cas is required for this process. Measurements of Texas Red-labeled EGF uptake and cell surface EGFR revealed that p130Cas overexpression reduces EGF-induced EGFR internalization, while p130Cas depletion enhances it. In addition, both FN-mediated cell adhesion and p130Cas overexpression reduce EGF-stimulated dynamin phosphorylation, which is necessary for EGF-induced EGFR internalization. Coimmunoprecipitation and GST pull-down assays confirmed the interaction between p130Cas and dynamin. Moreover, a SH3-domain-deleted form of p130Cas, which shows diminished binding to dynamin, inhibits dynamin phosphorylation and EGF uptake less effectively than wild-type p130Cas. CONCLUSIONS/SIGNIFICANCE: Our results show that p130Cas plays an inhibitory role in EGFR internalization via its interaction with dynamin. Given that the EGFR internalization process determines signaling density and specificity in the EGFR pathway, these findings suggest that the interaction between p130Cas and dynamin may regulate EGFR trafficking and signaling in the same manner as other endocytic regulatory proteins related to EGFR endocytosis