We evaluated changes of different soil nitrogen forms (total N, available ammonium and nitrate, total N in microbial biomass, and soil N mineralization) after conversion of semideciduous dry tropical ...forest in 5- and 18-year-old pastures (YP and OP, resp.) in the western Llanos of Venezuela. This evaluation was made at early rainy season, at end rainy season, and during dry season. With few exceptions, no significant differences were detected in the total N in the three study sites. Compared to forest soils, YP showed ammonium losses from 4.2 to 62.9% and nitrate losses from 20.0 to 77.8%, depending on the season of the year. In OP, the ammonium content increased from 50.0 to 69.0% at the end of the rainy season and decreased during the dry season between 25.0 and 55.5%, whereas the nitrate content increased significantly at early rainy season. The net mineralization and the potentially mineralizable N were significantly higher P < 0.05 in OP than in forest and YP, which would indicate a better quality of the substrate in OP for mineralization. The mineralization rate constant was higher in YP than in forest and OP. This could be associated with a reduced capacity of these soils to preserve the available nitrogen.
Night-shift work (NSW) has been suggested as a possible cause of breast cancer, and its association with mammographic density (MD), one of the strongest risk factors for breast cancer, has been ...scarcely addressed. This study examined NSW and MD in Spanish women.
The study covered 2,752 women aged 45-68 years recruited in 2007-2008 in 7 population-based public breast cancer screening centers, which included 243 women who had performed NSW for at least one year. Occupational data and information on potential confounders were collected by personal interview. Two trained radiologist estimated the percentage of MD assisted by a validated semiautomatic computer tool (DM-scan). Multivariable mixed linear regression models with random screening center-specific intercepts were fitted using log-transformed percentage of MD as the dependent variable and adjusting by known confounding variables.
Having ever worked in NSW was not associated with MD Formula: see text:0.96; 95% confidence interval (CI), 0.86-1.06. However, the adjusted geometric mean of the percentage of MD in women with NSW for more than 15 years was 25% higher than that of those without NSW history (MD
:20.7% vs. MD
:16.5%;Formula: see text:1.25; 95% CI,1.01-1.54). This association was mainly observed in postmenopausal participants (Formula: see text:1.28; 95% CI, 1.00-1.64). Among NSW-exposed women, those with ≤2 night-shifts per week had higher MD than those with 5 to 7 nightshifts per week (Formula: see text:1.42; 95% CI, 1.10-1.84).
Performing NSW was associated with higher MD only in women with more than 15 years of cumulated exposure. These findings warrant replication in futures studies.
Our findings suggest that MD could play a role in the pathway between long-term NSW and breast cancer.
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Introduction. The biotic fraction of the soil is the essential component in ecological processes and can influence
agricultural productivity of crops. Objective. To Identify the population of ...phytonematodes associated with plantain
plants vigor in the southern zone of lake Maracaibo, Venezuela. Materials and methods. Eight 2-hectare batches of
plantain plants (Musa AAB cv. Hartón), located in the south of lake Maracaibo, were selected and divided into two
1-hectare areas or lots, during October and December of the year 2018. The designation of the lots by vigor (HV= high
vigor and BV= low vigor) was made based on the parameters of the number of hands per cluster, circumference of the
mother plant, and the height of the son of succession, in twenty plants close to harvest, for each one. The soil sample
was collected at a depth of 15 cm on three newly flowered plants per lot and for the roots a microcalicata was made per
plant up to 30 cm deep. For the nematological extraction in the soil, the oostenbrink levigation method was used with
a Baermann funnel and the blending method was used as a root. Subsequently, the specimens found were quantified
by gender. Results. A population more significant (p<0,05) than in the root (2670 individuals) was found in the soil
(14 140 individuals). No statistical difference between AV (395) and BV (305) was observed when comparing the
total population by vigor. Twelve taxonomic genera were determined in the root and soil samples. The most prevalent
specimens in AV were Helicotylenchus multicinctus and Radopholus similis and in the BV lots it was Pratylenchus sp.
Conclusion. A high diversity of nematofauna present in both soils and roots of the crop was observed.
Introducción. La fracción biótica del suelo es el componente esencial en los procesos ecológicos y pueden
ejercer influencia en la productividad agrícola de los cultivos. Objetivo. Identificar la población de fitonematodos
asociados al vigor de las plantas de plátano en la zona de sur del lago de Maracaibo, Venezuela. Materiales y
métodos. Se seleccionaron ocho lotes de plantas de plátano (Musa AAB cv. Hartón) de 2 ha, ubicados en el sur del
lago de Maracaibo, los cuales se dividieron en dos áreas o lotes de 1 ha, durante octubre y diciembre del año 2018.
La designación de los lotes por vigor (AV= alto vigor y BV= bajo vigor) se realizó con base en los parámetros del
número de manos por racimo, circunferencia de la planta madre y altura del hijo de sucesión, en veinte plantas
próximas a la cosecha, por cada uno. La muestra de suelo se recolectó a 15 cm de profundidad en tres plantas recién
florecidas por lote y para las raíces se realizó una microcalicata por planta hasta 30 cm de profundidad. Para la
extracción nematológica en suelo se empleó el método de levigación de oostenbrink con embudo de Baermann y
en raíz el método de licuado. Posteriormente, se cuantificó por género los especímenes encontrados. Resultados. Se
encontró una población en el suelo (14 140 individuos) más significativa (p<0,05) que en la raíz (2670 individuos). Al
comparar la población total por vigor no se observó diferencia estadística entre AV (395) y BV (305). Se determinaron
doce géneros taxonómicos en las muestras de raíz y en suelo. Los especímenes más predominantes en AV fueron
Helicotylenchus multicinctus y Radopholus similis y en los lotes BV fue Pratylenchus sp. Conclusión. Se observó
una alta diversidad de la nematofauna presente tanto en los suelos como en raíces del cultivo.
Zinc is an essential trace element that plays a key role in the immune, gastrointestinal, respiratory and nervous systems
In Colombia, a vast percentage of children live in low-income households with ...food insecurity and nutritional deficiencies, including zinc. In an effort to improve children's well-being, public health measures such as nutritional support programs that provide meals have targeted the poorest populations. The aim of the present study was to assess the role of nutritional support programs on zinc deficiency in Colombian children, while considering their wealth and food security.
Cross-sectional study using data from the 2010 Colombian National Nutrition Survey, a population-based study representative of Colombia. A total of 4275 children between 12 and 59 months of age were included in the study. Stepwise logistic regressions were modelled with SPSS, first for zinc deficiency on wealth and food security, then adding enrolment in a nutritional support program, and finally, adjusting for socio-demographic variables.
A zinc deficiency prevalence of 49% was found. The adjusted models showed an association of wealth quintiles: very poor (OR = 1.48) and poor (OR = 1.39), food security (OR = 0.75) and enrolment in a nutritional support program (OR = 0.76) with zinc deficiency. Enrolment in nutritional programs did not modify the relationship of wealth and food security to zinc deficiency.
Zinc deficiency is associated with wealth, food security and enrolment in nutritional support programs. Nutritional programs may be a good alternative against zinc deficiency, if they focus appropriately on the needs of children according to their wealth and food security.
•We explored the possible link between night shift work and gynaecological cancer.•Our systematic review retrieved only relevant seven articles, which provided data from just six studies.•The ...relationship between night shift work and ovarian, endometrial or cervical cancer remains unclear.
Night shift work can affect hormonal balance, and so might be a risk factor for gynaecological malignancies. This report presents a systematic review on the association between this occupational exposure and the incidence of gynaecological cancers other than breast cancer. We searched for original articles addressing this issue in PubMed/MEDLINE, EMBASE and Web of Science, and used the Newcastle–Ottawa Quality Index to evaluate the methodological quality of those reports selected for review. Globally, we found only six articles, which provided the results of just six research studies: four examined ovarian cancer, two endometrial tumours and two cervical cancer. Our results show that this matter has received scant attention from the research community, and that the little evidence available does not show any clear relationship between night shift work and ovarian, endometrial or cervical cancer. More prospective rigorous studies are needed to evaluate these associations.
With the objective to contribute to a better understanding of ecological consequences of deforestation on the below-ground system in the Western Llanos of Venezuela, we evaluated the vertical ...distribution, nutrient concentration and seasonal changes of total fine root mass (FRM) (<2 mm diameter) in a semi-deciduous tropical dry forest and in 2 adjacent pastures of Cynodon nlemfuensis: a young pasture (YP, 5 years old) and an old pasture (OP, 18 years old) in the Obispo municipality, Barinas State. This evaluation included measurements at the end of the rainy season, during the dry season and during the subsequent early rainy season in 2005/2006. Highest FRM was recorded during the dry season, which probably indicates a plant water-stress response mechanism. The highest proportion (63‒88%) of FRM was concentrated in the 10–20 cm soil layer at all studied sites, probably due to a higher nutrient and moisture content at that depth. Non-significant differences (P>0.05) were observed in the total concentrations of organic carbon, nitrogen, phosphorus, calcium and magnesium in the FRM in soils supporting forest, OP and YP at the evaluated depths. Non-significant changes in the total FRM and nutrient concentrations were observed between the sampling periods and the 3 study sites. YP soils showed a slight increase in FRM that could be associated with the root growth of secondary vegetation, which is considered a weed and is periodically removed. Our results suggest that the land use change from tropical forest to pastures has not significantly affected the mass of fine roots and their carbon and nutrient concentrations. Further studies are needed to determine if these findings apply to other ecosystems.
Abstract Objective To estimate the prevalence of hepatitis B virus (HBV) infection and vaccine-induced immunity in the region of Madrid, and to analyze their evolution over time. Methods An ...observational, analytical, cross-sectional study was carried out in the population aged 16–80 years between 2008 and 2009. This was the last of four seroprevalence surveys in the region of Madrid. The prevalence of HBV infection and vaccine-induced immunity was estimated using multivariate logistic models and were compared with the prevalences in the 1989, 1993 and 1999 surveys. Results In the population aged 16–80 years, the prevalence of HBV infection was 11.0% (95% CI: 9.8–12.3) and that of chronic infection was 0.7% (95% CI: 0.5–1.1). The prevalence of vaccine-induced immunity in the population aged 16–20 years was 73.0% (95% CI: 70.0–76.0). Compared with previous surveys, there was a decrease in the prevalence of HBV infection. Conclusions Based on the prevalence of chronic infection (<1%), Madrid is a region with low HBV endemicity. Preventive strategies against HBV should especially target the immigrant population.
Hemeproteins play an important role in the signaling processes mediated by nitric oxide (NO). For example, the production of NO by nitric oxide synthase, the activation of guanylate cyclase by ...binding NO, and the scavenging of NO by hemoglobin, myoglobin, and cytochrome c oxidase all occur through unique mechanisms of interaction between NO and hemeproteins. Unlike carbon monoxide (CO) and oxygen (O2), which have been studied extensively, the reactions of NO with ferric and ferrous hemeproteins are not as well characterized. In this work, NO binding to myoglobin is studied using cryogenic optical spectroscopy and Fourier transform infrared spectroscopy (FTIR) in order to characterize the ligand-bound and photoproduct states involved in the interaction of NO with the heme iron and the distal pocket of the protein. For ferrous nitrosyl myoglobin (MbIINO), optical spectroscopy is used to show that the ligand-bound state can be converted to >95% stable photoproduct below 10 K. The Soret peak of the photoproduct is red-shifted by 4 nm relative to deoxy-myoglobin (Mb), similar to previous results for carbonmonoxy- (MbCO) and oxy-myoglobin (MbO2) (Miller et al., 1996). MbIINO completely rebinds by 35 K, indicating that the rebinding barrier for NO is lower than MbCO, consistent with room temperature picosecond kinetic measurements. For ferric nitrosyl myoglobin (MbIIINO), we find that the photoproduct yield at cryogenic temperatures is less than unity and dependent on the distal pocket residue. Native MbIIINO has a lower photoproduct yield than the mutant, MbIII(H64L)NO, where the distal histidine is replaced by leucine. The rebinding rates for the native and mutant species are similar to each other and to MbIINO. By using FTIR difference spectroscopy (photolyzed/unphotolyzed) of isotopically labeled ferrous nitrosyl myoglobin (MbIINO), the NO stretching frequencies in both the ligand-bound states and photoproduct states are determined. Two ligand-bound conformational states (1607 and 1613 cm-1) and two photoproduct conformational states (1852 and 1857 cm-1) are observed for MbIINO. This is the first direct observation of photolyzed NO in the distal pocket of myoglobin. The ligand-bound frequencies are consistent with a bent MbIINO moiety, where the unpaired π*(NO) electron remains localized on NO, causing ν(N−O) to be ∼300 cm-1 lower than MbIIINO. Similar to MbO2, we suggest that Nε of the distal histidine is protonated, forming a hydrogen bond to the NO ligand. For native MbIIINO, a single ligand-bound conformational state with respect to ν(N−O) is observed at 1927 cm-1. This frequency decreases to 1904 cm-1 for the mutant, MbIII(H64L)NO, contrary to the increase of the carbon monoxide (CO) stretching frequency in the isoelectronic MbII(H64L)CO mutant versus native MbCO. For linear MbIIINO, we suggest that backbonding from the unpaired π*(NO) electron to iron results in an increased positive charge on the NO ligand, Fe(δ-)−NO(δ+). This can be facilitated by tautomerism of the distal histidine, leaving Nε of the imidazole ring unprotonated and able to accept positive charge from the Fe(δ-)−NO(δ+) moiety, resulting in a higher bond order (and a 23 cm-1 shift to higher frequency) for native MbIIINO versus MbIII(H64L)NO, where this interaction is absent. These different interactions between the distal histidine and the ferrous versus ferric species illustrate potential ways the protein can stabilize the bound ligand and demonstrate the versatile nature by which NO can bind to hemeproteins.
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