Relative Importance Of Different Pathways Research Articles

Isotopic constraints on atmospheric sulfate formation pathways in the Mt. Everest region, southern Tibetan Plateau

Abstract. As an important atmosphere constituent, sulfate aerosols exert profound impacts on climate, the ecological environment, and human health. The Tibetan Plateau (TP), identified as the “Third Pole”, contains the largest land ice masses outside the poles and has attracted widespread attention for its environment and climatic change. However, the mechanisms of sulfate formation in this specific region still remain poorly characterized. An oxygen-17 anomaly (Δ17O) has been used as a probe to constrain the relative importance of different pathways leading to sulfate formation. Here, we report the Δ17O values in atmospheric sulfate collected at a remote site in the Mt. Everest region to decipher the possible formation mechanisms of sulfate in such a pristine environment. Throughout the sampling campaign (April–September 2018), the Δ17O in non-dust sulfate show an average of 1.7 ‰±0.5 ‰, which is higher than most existing data on modern atmospheric sulfate. The seasonality of Δ17O in non-dust sulfate exhibits high values in the pre-monsoon and low values in the monsoon, opposite to the seasonality in Δ17O for both sulfate and nitrate (i.e., minima in the warm season and maxima in the cold season) observed from diverse geographic sites. This high Δ17O in non-dust sulfate found in this region clearly indicates the important role of the S(IV)+O3 pathway in atmospheric sulfate formation promoted by conditions of high cloud water pH. Overall, our study provides an observational constraint on atmospheric acidity in altering sulfate formation pathways, particularly in dust-rich environments, and such identification of key processes provides an important basis for a better understanding of the sulfur cycle in the TP.

Food security in rural Burkina Faso: the importance of consumption of own-farm sourced food versus purchased food

BackgroundThe number of undernourished people and the risk of micro-nutrient deficiency remain high in sub-Saharan Africa (SSA). Decades of policy designed to reverse the trends of food insecurity have illustrated that the causal pathways of intervention to end-point outcomes, such as nutrition, are not necessarily straightforward. Utilising proxies for dimensions of food security, this study investigates the relative importance of different pathways to food security in two subtly contrasting communities in the Sahelian and Sudanian Savanna zones of Burkina Faso.ResultsIn Yatenga province, approximately 31% of households were classified as ‘severely food insecure’ in the ‘lean’ period. In contrast, over 84% of households sampled in Seno province were classified as being ‘severely food insecure’ in the ‘lean’ period. There were statistically significant associations between food security indicators and off-farm income, farm income and production diversity. The source of income had significantly different associations with diet diversity in the two provinces. In Yatenga province, higher gross farm income in the absence of off-farm income was predicted to result in more diverse diets; in Seno province, however, gross farm income was only predicted to result in more diverse diets when households are also earning off-farm income.ConclusionsOur analysis shows that households were most differentiated by income generating pathways to food security in the ‘lean’ period. This finding should not detract from the essential role played by home-produced foods in improving food security. Rather, market-orientated agriculture and production for home consumption, as shown by households in this study, can be combined as part of a more resilient livelihood strategy. Policy needs to be targeted towards agro-ecological conditions, as well as socioeconomic factors in order to facilitate improved on-farm income, farm resilience and off-farm employment opportunities.

Managing invasions by terrestrial alien plants in Ireland: challenges and opportunities

The successful management of plant invasions is a global concern, given the large ecological and economic impacts of many introduced plant species, which may be compounded by interactions with other environmental and socio-economic changes. With the aim of identifying the challenges and opportunities associated with the management of terrestrial plant invasions in Ireland, in the light of international obligations, we review some of the most important initiatives that have been conducted to manage current invasive alien plants and the principles that should guide their management and the restoration of invaded communities. While the focus of most management practices has been based on the application of herbicide treatments and/or mechanical removal, alternative approaches may be needed in the future due to general environmental or site-related concerns. The likelihood of the widespread and successful eradication of the most significant plant invaders is, however, unlikely and more focus needs to be on a prioritised approach that targets areas where they have the greatest impact. Our ability to do this is, however, limited due to a poor understanding of the long-term impacts of plant invasions and the effectiveness of many control measures that fail to recognise species- and habitat-specific factors. An improved understanding of how the relative importance of different pathways of introduction will change in the future is also needed, including the volumes of seed traded on the internet. A range of citizen science initiatives have been promoted to raise awareness of plant invasions, with the aim of reducing the demand for ornamental species and the unintentional spread of existing invaders. These will be important for the early detection and eradication of new introductions as well as limiting the spread of existing invaders. However, the effective control of existing plant invaders requires an all-island coordinated approach supported by appropriate resources and scientific expertise.

Managing invasions by terrestrial alien plants in Ireland: challenges and opportunities

The successful management of plant invasions is a global concern, given the large ecological and economic impacts of many introduced plant species, which may be compounded by interactions with other environmental and socio-economic changes. With the aim of identifying the challenges and opportunities associated with the management of terrestrial plant invasions in Ireland, in the light of international obligations, we review some of the most important initiatives that have been conducted to manage current invasive alien plants and the principles that should guide their management and the restoration of invaded communities. While the focus of most management practices has been based on the application of herbicide treatments and/or mechanical removal, alternative approaches may be needed in the future due to general environmental or site-related concerns. The likelihood of the widespread and successful eradication of the most significant plant invaders is, however, unlikely and more focus needs to be on a prioritised approach that targets areas where they have the greatest impact. Our ability to do this is, however, limited due to a poor understanding of the long-term impacts of plant invasions and the effectiveness of many control measures that fail to recognise species- and habitat-specific factors. An improved understanding of how the relative importance of different pathways of introduction will change in the future is also needed, including the volumes of seed traded on the internet. A range of citizen science initiatives have been promoted to raise awareness of plant invasions, with the aim of reducing the demand for ornamental species and the unintentional spread of existing invaders. These will be important for the early detection and eradication of new introductions as well as limiting the spread of existing invaders. However, the effective control of existing plant invaders requires an all-island coordinated approach supported by appropriate resources and scientific expertise.

Modeling the Toxicokinetics of Multiple Metals in the Oyster Crassostrea hongkongensis in a Dynamic Estuarine Environment.

Metal contamination is a major problem in many estuaries. Toxicokinetic models are useful tools for predicting metal accumulation in estuarine organisms and managing the associated ecological risks. However, obtaining toxicokinetic parameter values with sufficient predictive power is challenging for dynamic estuarine waters. In this study, we determined the toxicokinetics of multiple metals in the oyster Crassostrea hongkongensis in a dynamic estuary polluted by metals using a 48 day transplant experiment. During the experiment, metal concentrations in oysters, water, and suspended particles were intensively monitored at 3 day intervals. The toxicokinetic parameters were then estimated using the Markov chain Monte Carlo (MCMC) method. The calibrated model was capable of successfully simulating the time-course of metal bioaccumulation in oysters and was further validated by predicting the bioaccumulation at another site in the estuary. Furthermore, the model was used to assess the relative importance of different pathways in metal bioaccumulation. With the MCMC method, distributions instead of single values were assigned to model parameters. This method makes the model predictions probabilistic with clearly defined uncertainties, and they are thus particularly useful for the risk assessment of metals in aquatic systems.

Reaction of O(3P) with C3H6: Yield of the Reaction Products as a Function of Temperature.

Reaction of oxygen atoms with propene is an important step in combustion processes particularly affecting the profiles of intermediate species and flame speed. The relative importance of different pathways of this multichannel reaction at different temperatures represents significant theoretical interest and is essential for modeling combustion systems. In the present work, we report the first experimental investigation of the products of the O(3P) + C3H6 reaction over an extended temperature range (298-905 K). By using a low pressure flow reactor combined with a quadrupole mass spectrometer, the yields of the five reaction products, H atom, CH3, C2H5, CH2O and OH were determined as a function of temperature between 298 and 905 K: 0.0064 × (T/298)2.74 exp(765/T), 1.41 × (T/298)-1.0 exp(-335/T), 0.92 × (T/298)-1.41 exp(-381/T), 0.17 × (T/298)0.165 exp(-36/T), and 0.0034 × (T/298)2.34 exp(788/T), respectively (corresponding to the variation of the respective yields between 298 and 905 K in the ranges 0.08-0.31, 0.46-0.32, 0.26-0.12, 0.15-0.19, and 0.05-011), independent of pressure in the range 1-8 Torr of helium. For the yields of the minor reaction products, H2 and CH3CHO the upper limits were determined as 0.2 and 0.05, respectively. These results are compared with the experimental data and theoretical calculations available in the literature.

Reaction of O(3P) with C2H4: Yield of the Reaction Products as a Function of Temperature.

Reaction of oxygen atoms with ethylene is an important step in the combustion process particularly affecting the profiles of intermediate species and flame speed. Currently, the relative importance of different pathways of this multichannel reaction at different temperatures is not fully established and determination of the branching ratios for different reaction channels as a function of temperature remains essential for modeling combustion systems. In the present work, the products of the O(3P) + C2H4 reaction have been studied over an extended temperature range (297-900 K) using a low pressure flow reactor (1-8 Torr) combined with a quadrupole mass spectrometer. The yields of the three main reaction products, H atom, CH3 radical, and CH2O, were determined to be 0.31 ± 0.05, 0.53 ± 0.09, and 0.17 ± 0.03, respectively, independent of pressure and temperature under experimental conditions of the study. For the yields of the minor reaction products, H2 and CH4, the upper limits were determined as 0.05 and 0.02, respectively. These results are compared with the experimental data and theoretical calculations available in the literature.

On-the-fly Neutron Tomography of Water Transport into Lupine Roots

Measurement and visualization of water flow in soil and roots is essential for understanding of how roots take up water from soils. Such information would allow for the optimization of irrigation practices and for the identification of the optimal traits for the capture of water, in particular when water is scarce. However, measuring water flow in roots growing in soil is challenging. The previous 2D experiments (Zarebanadkouki et al., 2012) have not been sufficient for understanding the water transport across the root and therefore we employed an on-the-fly tomography technique with temporal resolution of three minutes. In this paper, we show that the series of on-the-fly neutron tomographic experiments performed on the same sample allow for monitoring the three-dimensional spatial distribution of D2O across the root tissue. The obtained data will allow us to calculate the convective and diffusive transport properties across root tissue and to estimate the relative importance of different pathways of water across the root tissue.

Using muscle gene expression to estimate triacylglyceride deposition, and relative contributions of fatty acid synthesis and fatty acid import in intramuscular fat in cattle

Intramuscular fat content (IMF%) in cattle influences the value of individual animals, especially for higher marbling markets. IMF is triacylglyceride (TAG) in lipid droplets in the intramuscular adipocytes. However, there are many different pathways from feed intake to the final common process of TAG synthesis and storage as IMF. To evaluate the relative importance of different pathways we compared changes in the expression of genes encoding proteins involved in the TAG and fatty acid (FA) synthesis pathways in the longissimus muscle of Piedmontese × Hereford (P×H) and Wagyu × Hereford (W×H) crosses. Based on these changes we have estimated the relative contributions of FA synthesised de novo in the intramuscular adipocyte and the uptake of circulating FA (both free and from TAG), from the diet or synthesised de novo in other tissues, to TAG deposition as IMF. We have analysed the impact of different developmental times and different diets on these processes. Increased de novo FA synthesis in intramuscular adipocytes appeared to contribute more than increased FA uptake from circulation to the additional TAG deposition in W×H compared with P×H cattle between 12 and 25 months (forage diet). Changing diet from forage to concentrate appeared to increase the importance of FA uptake from circulation relative to de novo FA synthesis for TAG synthesis in intramuscular adipocytes. These results are consistent with the literature based on analysis of lipid composition. Gene expression appears to provide a simple assay for identification of the source of FA for the deposition of IMF.

580: A pathway analysis of imprinted genes in developing placentae

genes in developing placentae Jennifer King, Kai Wang, Huaiyu Mi, Nicole Bender, Rachel Steward, Sue Ingles, Joseph Ouzounian, Melissa Wilson University of Southern California, Department of Obstetrics and Gynecology, Los Angeles, CA, University of Southern California, Department of Psychiatry and The Behavioral Sciences, Los Angeles, CA, University of Southern California, Department of Preventive Medicine, Los Angeles, CA OBJECTIVE: Genomic imprinting has been demonstrated to be integral to fetal development and placentation. The majority of studies on imprinted gene expression in humans have involved term placentas, while placental imprinting is known to be a dynamic process, which evolves during human pregnancy. For these reasons, the distinct imprinted gene expression profile displayed in the early human placenta remains largely unknown. Our objective was to investigate the pattern of imprinted gene expression across first and early second trimester placental development. STUDY DESIGN: We sequenced complementary cDNA from placental villi obtained at 7, 8, 9, and 15 weeks gestation using massively parallel next-generation sequencing (RNA-seq). We used the PANTHER classification system (http://www.pantherdb.org/about.jsp) to evaluate imprinted gene expression at each gestational age in reference to the human genome. We performed a pathway analysis to determine important processes at each time point that differ from the human genome using the Wilcoxon Rank Sum test. We did not use a Bonferroni correction due to the exploratory nature of the analysis. We report the top 15 pathways for each gestational age. RESULTS: Table includes top 15 pathways for each gestational age, none of which are statistically significant after Bonferroni correction. CONCLUSION: Similarities between global gene expression pathways and imprinted gene pathways speak to the importance of imprinted genes in the developing placenta. Imprinted genes have variable expression in early placental development. The top pathway for gestational ages of 8 and 9 weeks appear remarkably similar. At 15 weeks, the molecular pathways of the imprinted genes are notably different compared to earlier gestational age. These observations may reflect changes in imprinted gene expression that occur with changes in oxygen pressure or may be a result of small sample size. Larger studies are required to differentiate. 581 A pathway analysis of the developing placentome Jennifer King, Kai Wang, Huaiyu Mi, Ian Tilley, Rachel Steward, Sue Ingles, Joseph Ouzounian, Melissa Wilson University of Southern California, Department of Obstetrics and Gynecology, Los Angeles, CA, University of Southern California, Department of Psychiatry and The Behavioral Sciences, Los Angeles, CA, University of Southern California, Department of Preventive Medicine, Los Angeles, CA OBJECTIVE: The creation of a suitable intrauterine environment for fetal development is dependent on the proper functioning of placental chorionic villi. Chorionic villi require well-coordinated expression of several transcription factors, cytokines and their receptors, growth factors, and cell cycle regulators. Disruption of the expression of these regulatory factors may lead to placental growth and development disorders. However, gene expression levels across gestatational age have not been fully delineated. Our objective was to investigate the pattern of global gene expression across first and early second trimester placental development. STUDY DESIGN: In the present investigation, we sequenced complementary cDNA from placenta villi obtained at 7, 8, 9, and 15 weeks gestation, using massively parallel next-generation sequencing (RNAseq). We used the PANTHER classification system (http://www.pantherdb.org/about.jsp) to evaluate global gene expression at each gestational age in reference to the human genome. We performed a pathway analysis to determine important processes at each time point that differ from the human genome using the Wilcoxon Rank Sum test with a Bonferroni correction for multiple comparisons. RESULTS: See Table. CONCLUSION: Pathways involved in protein degradation, and regulation of trophoblast invasion are important at all four gestational ages. However, the relative importance of different pathways diverges after that point among the four gestational ages. The possible clinical significance of the ubiquitin proteasome pathway may be underappreciated to date. Additional analyses with a larger sample size are required to understand how these pathways may play a role in predisposing to diseases of placental etiology, such as preeclampsia or intrauterine growth restriction. Pathway description, ( )over or ( )under represented vs human genome (reference) Poster Session IV Academic Issues, Antepartum Fetal, Clinical Ob, Fetus, Genetics, Hypertension, Med-Surg-Diseases, Operative Ob, U/S www.AJOG.org

Acute Toxicity of Cadmium inDaphnia magnaunder Different Calcium and pH Conditions: Importance of Influx Rate

Water chemistry is generally thought to influence metal toxicity via affecting metal bioavailability and bioaccumulation, but its effects on tissue residue-based toxicity are poorly known. We conducted toxicity tests in parallel with uptake kinetics experiments of cadmium (Cd) in waters of different calcium (Ca) concentrations and pH levels using acclimated Daphnia magna as a model organism. Both the acute toxicity and uptake of Cd were reduced by higher Ca concentration and lower pH. Strikingly constant median effective influx rates (EJ(50), 1.3-1.6 μg g(-1) h(-1)) of Cd were observed when the concentration of Ca varied from 0.5 to 200 mg L(-1), indicating that acclimation to different Ca levels did not affect the tissue residue-based toxicity. The EJ(50) values increased consistently with decreasing pH level, showing that acclimation to acidic water decreased the tissue residue-based toxicity. With the use of calcium uptake inhibitors, we demonstrated that both Ca channel and Ca(2+)/Na(+) exchanger were involved in Cd uptake in daphnids, but there were also other possible pathways with higher affinity. The relative importance of different pathways was clearly dependent on the ambient Ca availability. Our findings are helpful for the development of a more accurate biotic ligand model in predicting the acute toxicity of Cd to daphnids.

Effects of sulfur on PCDD/F formation under stable and transient combustion conditions during MSW incineration

SO 2 levels in the flue gas from a laboratory-scale fluidized bed reactor combusting artificial municipal solid waste (MSW) were varied (resulting in four different SO 2:HCl ratios 0, 0.2, 0.7 and 2.7 (by mass)) to study the effects of sulfur on the formation of polychlorinated dibenzo- p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzothiophenes (PCDTs). Sampling was performed simultaneously at three fixed points in the post-combustion zone with temperatures of 400, 300 and 200 °C, under normal combustion conditions and both during and after transient combustion conditions. The findings indicate that sulfur has a greater inhibitory effect on PCDF formation than on PCDD formation and that the PCDD/PCDF ratio in the flue gas depends on both the SO 2:HCl ratio in the flue gas and memory effects arising from transient combustion conditions. The results also indicate that the relative importance of different pathways shifts in the post-combustion zone; condensation products increasing with reductions in temperature and increases in residence time. However, these changes appear to depend on the SO 2:HCl ratio in the flue gas and combustion conditions. Sulfur seems to inhibit the chlorination of PCDFs. A tendency for increased SO 2 levels in the flue gas to increase levels of PCDTs was also detected, but the increases were much less significant than the reductions in PCDF levels.

Does Inhibition of Glycogen Synthase Kinase Protect in Mice?

See related article, pages 307–314 Preconditioning (PreC) and postconditioning (PostC) have been shown to initiate a number of signaling cascades that reduce cell death. However, the mechanisms by which these signals reduce cell death have been elusive.1 PreC has been shown to phosphorylate and thereby inhibit glycogen synthase kinase (GSK)-3β, and perfusion with GSK inhibitors has been shown to reduce cell death induced by ischemia/reperfusion, when added before ischemia2 or when added at the start of reperfusion.3–5 These studies are consistent with data in other tissues showing that inhibition of GSK-3β reduces apoptosis. Information regarding the mechanism by which inhibition of GSK protects has been provided by Juhaszova et al,6 who report that inhibition of GSK-3β delays the opening of the mitochondrial permeability transition pore (MPT) (see the Figure). The MPT is a large-conductance pore in the inner mitochondrial membrane which is opened under conditions associated with ischemia/reperfusion, such as high matrix reactive oxygen species and high matrix calcium. Pharmacological inhibitors of the MPT have been shown to reduce ischemia/reperfusion injury, suggesting that activation of MPT might have a role in ischemia/reperfusion-mediated cell death. However the molecular components of the MPT have not been identified.7 Figure. Nishino et al8 raise 2 questions: (1) whether inhibition of GSK is required for protection in mice; and (2) whether inhibition of GSK is protective in mouse hearts. PreC and PostC activate a number of redundant signaling pathways that lead to inhibition of MPT. The relative importance of different pathways may vary depending on the model and species. Previous studies6 have suggested that inhibition of GSK is a major signaling pathway that results in inhibition of MPT; this is illustrated with the large arrow. However, other pathways exist and it is not surprising that under different …

Commentary: Modelling multiple pathways to explain social inequalities in health and mortality

Investigations into socioeconomic inequalities in health and mortality have primarily been carried out in the US and in Europe, 1‐3 therefore reports from other parts of the world are a welcome addition to the effort to explicate pathways linking social structure to health and mortality. Research on social inequalities in Korea is particularly interesting as it has undergone rapid industrialization, with the GDP per head increasing 100-fold in � 40 years. 4 In this issue of the International Journal of Epidemiology, Khang and colleagues show socioeconomic differentials in mortality in South Korea to be better explained by early life exposures compared with biological risk factors, health behaviours, and psychosocial factors. 5 The authors point out that it is the latter that explain more of the social gradient in mortality in the western countries. They argue that this discrepancy in the relative importance of different pathways might lie in the differential cause-specific structure of mortality in Korea. The authors recognize that this hypothesis needs to be further tested in agespecific analyses in order to control for cohort effects, before firm conclusions about the relative importance of different pathways can be drawn. In this commentary, I suggest that another aspect that requires further effort is attention to the modelling of interrelationships between variables. The examination of pathways explaining socioeconomic differentials in mortality is not straightforward. Consider a simple example with three variables: an exposure (X), here socioeconomic position; an outcome (Y), here mortality, and a third related variable (A). These variables could be associated with each other in at least four different ways (Figure 1), described below; each of which would require a different statistical treatment to assess the impact of X and A on Y. 1. The relationship between X and Y could be mediated by an intervening causal variable, A. This could either be a single variable (A) or a series of variables (A1, A2, A3, etc). Thus the exposure would have a ‘direct’ effect (pathway XY) on the outcome and (or) an ‘indirect’ effect (pathway XA + AY), mediated through its effect on A. 2. The relationship between X and Y could be moderated by a variable, A. This implies that the strength of the relationship between the exposure (X) and the outcome (Y) would depend upon the moderator (or effect modifier), as this variable specifies the conditions under which X will produce Y.

Estimation of the nutrient inputs into river systems - experiences from German rivers

The nutrient discharges from point and diffuse sources in more than 200 German river basins were estimated for the periods 1983–1987 and 1993–1997 employing the MONERIS model. This model distinguishes between six diffuse pathways and point source emissions from waste water treatment plants and direct industrial discharges. It was estimated that the total nitrogen input into the German river systems amounts to about 819,000 t N year–1 in the period 1993 to 1997. These emissions have decreased since the mid-eighties by about 266,000 t N year–1, mainly caused by the reduction of point discharges. For phosphorus the emissions have been reduced by 56,290 t P year–1 and amount to 37,250 t P year–1 in the period 1993–1997. Based on emission data a retention module estimates riverine nutrient loads. The comparison of the model output with the observed loads shows a deviation as low as 30% and 50% for nitrogen and phosphorus, respectively. The regional resolution of the model indicates the relative importance of different pathways for phosphorus and nitrogen input into river systems.

Nitrogen Retention and Release in Atlantic White Cedar Wetlands

AbstractThe fate of N inputs to freshwater wetlands from enriched runoff, ground water, or atmospheric deposition reflects a variety of processes that determine the net retention of N or its release to downstream ecosystems. The history of N enrichment may affect the relative importance of different pathways. We compared the ability of sediments from Atlantic cedar wetlands in suburban and undisturbed watersheds to remove added inorganic N in laboratory incubations. Three pulses of NH4NO3, at 50 mg N L−1 concentration, were added at consecutive 2‐wk intervals as an analog of pulsed stormwater inputs. After each incubation, soils were leached with CaCl2 and inorganic N concentrations in the leachate were analyzed. The peats retained added N during the first incubation, but after the second and third, all soils released more N than had been added. Nitrate concentrations were always lower than ammonium concentrations. Soils from hollows and most hummocks retained added nitrate throughout the study, but all soils released ammonium. Soil extractable ammonium increased four to 10 times after the 6‐wk incubation, while extractable dissolved organic N (DON) decreased. There also was a net decrease of soil total Kjeldahl N (TKN). The patterns of retention and release of nitrate and ammonium were correlated positively with the N mineralization and nitrification rates of the soils. Our results suggest that wetland peats in suburban drainages may have limited ability to retain frequent, pulsed N inputs from runoff and high intrinsic N mineralization in N‐saturated sediments can become a cause of water quality degradation.

Marked differences in the frequency of microsatellite instability in gastric cancer from different countries

OBJECTIVE: Previous studies have reported variable rates of microsatellite instability (MSI) in gastric cancer. We investigated the frequency of MSI in invasive gastric carcinoma of patients from three geographic regions. METHODS: Genomic DNA from gastric cancer and nontumor tissue from 22 Korean, 20 Colombian, and 26 U.S. patients was amplified with five microsatellite markers. RESULTS: MSI was more frequently seen in gastric cancer from Korea, affecting 50% of patients, in contrast with gastric cancers from the U.S. (7%) and Colombia (15%) ( p = 0.003 and p = 0.03, respectively). MSI at one locus was significantly more frequent in gastric cancer from individuals >65 yr ( p = 0.01). MSI was similarly associated with both diffuse and intestinal types of gastric cancer. CONCLUSIONS: MSI affects the two major histological types of gastric cancer, and was more frequent in gastric cancer from Korea than in the other countries, suggesting that the relative importance of different pathways of gastric carcinogenesis may vary in diverse regions of the world.

Cross-colonisation with Pseudomonas aeruginosa of patients in an intensive care unit

BACKGROUNDVentilator-associated pneumonia (VAP) caused by Pseudomonas aeruginosa is usually preceded by colonisation of the respiratory tract. During outbreaks, colonisation with P aeruginosa is mainly derived from exogenous sources. The relative...

A mathematical model for cadmium in the stone loach ( Noemacheilus barbatulus L.) from the River Ecclesbourne, Derbyshire

A mathematical model which linked metabolism of stone loach with cadmium dynamics was developed using information from laboratory experiments and field studies. Three possible sources of cadmium were distinguished: water, food, and sediment. Predicted results over 1 year were compared with field observations from three sites in Derbyshire. The model adequately predicted growth of fish for all three sites. Predicted cadmium levels in loach were in good agreement with measured levels in fish from all three sites despite the fact that concentrations of cadmium in the environment were kept constant during each simulation. The weight of fish affected the relative importance of different pathways of cadmium intake under similar conditions. Uptake from water contributed substantially to body burden even though the concentration in water was lower than that in food or in sediment. However, uptake from both food and sediment could not be ignored given the measured levels of cadmium in the field. The relative importance of uptake from the three sources also differed with site. The model showed that metabolism, affected by temperature, is important to the dynamics of cadmium in the stone loach.

Zinc Regulation in the LobsterHomarus Gammarus:Importance of Different Pathways of Absorption and Excretion

Zinc is one of the most important of the essential trace metals and more than 90 zinc-containing enymes and proteins have been discovered: furthermore, zinc increases the activity of many other enzymes (Vallee, 1978). It is not surprising, therefore, that in some groups of animals the body concentration is regulated against fluctuations in intake. Decapod crustaceans comprise one such group, although the ways in which regulation is achieved vary from species to species. In the freshwater crayfish,Austropotamobius pallipes, excretion in the faeces is a major pathway for removing zinc (Bryan, 1967a) whereas in the shore crabCarcinus maenaslosses over the body surface also assume considerable importance (Bryan, 1966). On the other hand, preliminary work on the lobsterHomarus gammarus(formerlyH. vulgaris) suggests that in this species urinary excretion plays a major role in regulation (Bryan, 1964). The present work continues the study of zinc regulation in lobsters and its main aims are: (1) to measure rates of absorption from sea water over a wide range of concentrations and study the uptake mechanism; (2) to examine absorption from the stomach under different conditions; (3) to determine the relative importance of different pathways for the removal of zinc in response to various levels of intake.