Turing instabilities in a mathematical model for signaling networks

GTPase molecules are important regulators in cells that continuously run through an activation/deactivation and membrane-attachment/membrane-detachment cycle. Activated GTPase is able to localize in parts of the membranes and to induce cell polarity. As feedback loops contribute to the GTPase cycle and as the coupling between membrane-bound and cytoplasmic processes introduces different diffusion coefficients a Turing mechanism is a natural candidate for this symmetry breaking. We formulate a mathematical model that couples a reaction-diffusion system in the inner volume to a reaction-diffusion system on the membrane via a flux condition and an attachment/detachment law at the membrane. We present a reduction to a simpler non-local reaction-diffusion model and perform a stability analysis and numerical simulations for this reduction. Our model in principle does support Turing instabilities but only if the lateral diffusion of inactivated GTPase is much faster than the diffusion of activated GTPase.Comment: 23 pages, 5 figures; The final publication is available at http://www.springerlink.com http://dx.doi.org/10.1007/s00285-011-0495-

Contamination level and spatial distribution of heavy metals in water and sediments of El Guájaro Reservoir, Colombia

Heavy metals have become a subject of special concern worldwide, mainly due to high persistence in the environment, toxicity, biogeochemical recycling and ecological risk. Therefore, the objective of this investigation was to analyze the spatial–temporal distribution of heavy metals in water and sediments to determine the environmental status of El Guájaro Reservoir, where such studies have not been developed. Two measurement campaigns (dry and wet period) were carried out and eight sampling stations were selected. A comparison of water and sediment quality parameters with existing national and international regulations was done. Also, heavy metal distribution maps were generated, and the geoaccumulation index was calculated to identify sources and sediments contamination level. Based on the obtained results, agriculture and mining activities are the main causes of the reservoir contamination. This metals levels could be a potential risk for the aquatic life and the populations that are supplied from this water body

Diets containing sea cucumber (Isostichopus badionotus) meals are hypocholesterolemic in young rats

Peer reviewedPublisher PD

Mortalidad y recurrencia de la enfermedad tromboembólica venosa en pacientes adultos: cohorte prospectiva

INTRODUCCIÓN: La enfermedad tromboembólica venosa (ETV) es una patología que aumenta con la edad. Objetivo: comparar la sobrevida de los ancianos y los jóvenes con un primer episodio de ETV aguda y sintomática. MATERIALES Y MÉTODOS: Cohorte prospectiva de casos incidentes de ETV incluidos en el Registro Institucional de Enfermedad Tromboembólica venosa (NCT01372514) del Hospital Italiano de Buenos Aires entre 2012-2014, dividido en grupos jóvenes (17-64 años) y ancianos (≥ 65 años). Todos los pacientes fueron seguidos anualmente para evaluar el tiempo a la recurrencia (progresión o nuevo evento sintomático de ETV) como eventos competitivos en contexto de muerte y sangrado mayor. Se presentaron los riesgos crudos (c) y ajustados (a). RESULTADOS: se incluyeron 446 pacientes, el 63% (292) fueron mayores de 65 años. La sobrevida fue menor en los ancianos comparados con los jóvenes (p 0.007), a los 3 meses 87% vs 95% y al año 73% vs 87%, respectivamente. Los ancianos presentaron un HRc1,71 y HR a 1.68. La recurrencia global fue 5% (IC 95% 3-8) al mes, 6% (IC 95% 4-9) a los 3 meses, 8% (IC 95% 6-11) al año y 13% (IC 95% 9-18) a los dos años. No se encontró asociación entre la edad y la recurrencia sub hazard 0.8(IC 0,34-1,86). El sangrado ocurrió en un 9% (39) de los pacientes. CONCLUSIONES: La mortalidad global en pacientes con ETV confirmada es mayor en la población anciana. No hubo diferencias en relación a la recurrencia de ETV, ni el sangrado y tampoco con la edad

Reduced susceptibility to pyrethroid insecticide treated nets by the malaria vector Anopheles gambiae s.l. in western Uganda

<p>Abstract</p> <p>Background</p> <p>Pyrethroid insecticide-treated mosquito nets are massively being scaled-up for malaria prevention particularly in children under five years of age and pregnant mothers in sub-Saharan Africa. However, there is serious concern of the likely evolution of widespread pyrethroid resistance in the malaria vector <it>Anopheles gambiae s.l</it>. due to the extensive use of pyrethroid insecticide-treated mosquito nets. The purpose of this study was to ascertain the status of pyrethroid resistance in <it>An. gambiae s.l</it>. in western Uganda.</p> <p>Methods</p> <p>Wild mosquitoes (1–2 days old) were exposed in 10 replicates to new nets impregnated with K-othrine (Deltamethrin 25 mg/m²), Solfac EW50 (Cyfluthrin 50 mg/m²) and Fendona 6SC (Cypermethrin 50 mg/m²) and observed under normal room temperature and humidity (Temperature 24.8°C���27.4°C, Humidity 65.9–45.7). A similar set of mosquitoes collected from the control area 80 km away were exposed to a deltamethrin 25 mg/m²impregnated net at the same time and under the same conditions. The 10-year mean KDT₅₀and mortality rates for each of the three pyrethroid insecticides were compared using the Student <it>t</it>-test.</p> <p>Results</p> <p>A significant increase in the mean knockdown time (KDT₅₀) and mean mortality rate were observed in almost all cases an indication of reduced susceptibility. The overall results showed a four-fold increase in the mean knockdown time (KDT₅₀) and 1.5-fold decrease in mortality rate across the three pyrethroid insecticides. There was a significant difference in the 10-year mean KDT₅₀between deltamethrin and cyfluthrin; deltamethrin and cypermethrin, but no significant difference between cyfluthrin and cypermethrin. The 10-year mean difference in KDT50 for mosquitoes exposed to deltamethrin from the control site was significantly different from that of mosquitoes from the intervention site (p<0.05, t=3.979, 9df). The 10-year mean difference in mortality rate between deltamethrin (84.64%); cyfluthrin (74.18%); cypermethrin (72.19%) and the control (90.45%) showed a significant decline in mortality across all the three insecticides.</p> <p>Conclusion</p> <p>Generally the results showed a trend of increase in mosquito resistance status with cross-resistance against all the three pyrethroid insecticides. This study reveals for the first time the development of pyrethroid resistance in <it>An. gambiae s.l</it>. in Western Uganda. It is therefore strongly recommended that the impact of this development on malaria control efforts be closely monitored and alternative fabric treatments be considered before this problem curtails community wide implementation of this malaria control strategy in Uganda.</p

The association of mammographic density with ductal carcinoma in situ of the breast: the Multiethnic Cohort

INTRODUCTION: It is well established that women with high mammographic density are at greater risk for breast cancer than are women with low breast density. However, little research has been done on mammographic density and ductal carcinoma in situ (DCIS) of the breast, which is thought to be a precursor lesion to some invasive breast cancers. METHOD: We conducted a nested case-control study within the Multiethnic Cohort, and compared the mammographic densities of 482 patients with invasive breast cancer and 119 with breast DCIS cases versus those of 667 cancer-free control subjects. A reader blinded to disease status performed computer-assisted density assessment. For women with more than one mammogram, mean density values were computed. Polytomous logistic regression models were used to compute adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for two measurements of mammographic density: percentage density and dense area. RESULTS: Mammographic density was associated with invasive breast cancer and breast DCIS. For the highest category of percentage breast density (≥50%) as compared with the lowest (<10%), the OR was 3.58 (95% CI 2.26–5.66) for invasive breast cancer and 2.86 (1.38–5.94) for breast DCIS. Similarly, for the highest category of dense area (≥45 cm(2)) as compared with the lowest (<15 cm(2)), the OR was 2.92 (95% CI 2.01–4.25) for invasive breast cancer and 2.59 (1.39–4.82) for breast DCIS. Trend tests were significant for invasive breast cancer (P for trend < 0.0001) and breast DCIS (P for trend < 0.001) for both percentage density and dense area. CONCLUSION: The similar strength of association for mammographic density with breast DCIS and invasive breast cancer supports the hypothesis that both diseases may have a common etiology

Nε−Lysine Acetylation of a Bacterial Transcription Factor Inhibits Its DNA-Binding Activity

Evidence suggesting that eukaryotes and archaea use reversible Nε-lysine (Nε-Lys) acetylation to modulate gene expression has been reported, but evidence for bacterial use of Nε-Lys acetylation for this purpose is lacking. Here, we report data in support of the notion that bacteria can control gene expression by modulating the acetylation state of transcription factors (TFs). We screened the E. coli proteome for substrates of the bacterial Gcn5-like protein acetyltransferase (Pat). Pat acetylated four TFs, including the RcsB global regulatory protein, which controls cell division, and capsule and flagellum biosynthesis in many bacteria. Pat acetylated residue Lys180 of RcsB, and the NAD+-dependent Sir2 (sirtuin)-like protein deacetylase (CobB) deacetylated acetylated RcsB (RcsBAc), demonstrating that Nε-Lys acetylation of RcsB is reversible. Analysis of RcsBAc and variant RcsB proteins carrying substitutions at Lys180 provided biochemical and physiological evidence implicating Lys180 as a critical residue for RcsB DNA-binding activity. These findings further the likelihood that reversible Nε-Lys acetylation of transcription factors is a mode of regulation of gene expression used by all cells

Canine visceral leishmaniasis: study of methods for the detection of IgG in serum and eluate samples

The Brazilian Ministry of Health recommends the culling and euthanasia of dogs with a positive serological test for canine visceral leishmaniasis (CVL). In the Municipality of Rio de Janeiro, the technique used for the diagnosis of CVL is the indirect fluorescent antibody test (IFAT), using blood samples eluted on filter paper (eluate). A dog survey was conducted over a period of one year in the region of Carapiá, in order to evaluate the diagnosis of CVL in this region. All animals underwent clinical examination, and blood samples (serum and eluate) were collected for analysis by enzyme immunoassay (ELISA) and IFAT. A skin biopsy was obtained for parasitological examination (culture). A total of 305 animals were studied and Leishmania chagasi was isolated from nine animals. Sensitivity and specificity were 100% and 96.6% for ELISA, respectively, 100% and 65.5% for IFAT (cut-off at a 1:40 dilution), 100% and 83.4% for IFAT (cut-off at a 1:80 dilution), and 22.2% and 97.0% for eluate IFAT. In conclusion, ELISA was the best tool for the diagnosis of CVL among the serological techniques tested. The present results suggest the need for a better evaluation of filter paper IFAT as the only diagnostic method for CVL in the Municipality of Rio de Janeiro.O Ministério da Saúde recomenda a eutanásia de cães sororreatores como controle da leishmaniose visceral canina (LVC). No Município do Rio de Janeiro, a técnica utilizada para o diagnóstico da LVC é o teste de imunofluorescência indireta (IFI), utilizando amostras de sangue eluídas em papel de filtro (eluato). Um levantamento, durante um ano, foi conduzido na região de Carapiá, a fim de avaliar o diagnóstico da LVC nesta região. Todos os animais foram submetidos a exame clínico e coleta de sangue (soro e eluato) para realização do ensaio imunoenzimático (ELISA) e imunofluorescência indireta (IFI). Biópsia de pele foi obtida para o exame parasitológico (cultura). Foram avaliados 305 (89,4%) animais de uma população de 341 cães e Leishmania chagasi foi isolada de nove animais. A sensibilidade e especificidade do ELISA foram de 100% e 96,6%, na IFI (ponto de corte 1:40) de 100% e 65,5%, na IFI (ponto de corte 1:80) de 100% e 83,4% e na IFI (eluato) de 22,2% e 97,0%, respectivamente. A partir dos resultados obtidos podemos concluir que entre as técnicas sorológicas empregadas, o teste de ELISA apresentou-se como a melhor ferramenta para o diagnóstico da LVC. Os resultados sugerem a necessidade de uma melhor avaliação do teste de IFI realizada com eluato, como único método de diagnóstico para LVC no município do Rio de Janeiro