Pathogenicity of Helicobacter pylori: A perspective

Posted in: Environment by admin on January 1, 1993 | No Comments

Understanding of the pathogenesis of H. pylori-associated gastroduodenal disease is in its infancy. Lack of adequate animal models is a major problem in testing many of the current hypotheses. Study of gastritis and its initiating factors is possible with helicobacter-infected rodents. However, a model of ulcerogenesis and carcinogenesis is needed; possibly the ferret will be suitable. The other priority is to advance our understanding of the genetics of the helicobacters. Experience gained with the close relatives, the campylobacters, has produced shuttle vectors that can take H. pylori genes into E. coli, but there have been difficulties in expression of these genes. Thus, at present the potential for fulfilling the modified Koch’s postulates of molecular pathogenesis is limited. The discovery of H. pylori is another event in the renaisance of medical microbiology that has seen the discovery of the etiology agents of Lyme disease, Legionnaires’ disease, campylobacter-induced diarrheal disease, and AIDS. Better understanding of the pathogenicity of H. pylori will allow development of strategies to reduce morbidity and mortality due to two of the world’s major gastroduodenal diseases, namely, peptic ulceration and gastric cancer.

Reduction of N Pollution by Decrease of the Excretion of Endogenous N in Pigs

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Reduction of endogenous nitrogen results in the reduction of N in the feces but also in the urine.

Bestimmung der Geruchsstoffimmission durch Begehungen – Determination of Odorants in Ambient Air by Field Inspections

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In most cases the analysis of an odour in ambient air is complex because it is composed of mixed substances. Those substances taken individually are difficult and costly to measure because often their concentrations are low. The method described in the guideline evaluate an odorant in ambient air directly by use of human smell by measuring the percentage odour time (time fraction during one measurement duration when an odour is recognizable) and possibly the odour intensity (in a scale from 0 – no odour to 6 – extremely strong. VDI 3882 Part 1). Measurements are done over a period of 1 year or 6 months by a panel of assessors presenting certain characteristics (details about the panel selection are given in the publication). In the area where an emission occur an assessment area is defined according to the objective of the study. To evaluate the odour situation of this area, a grid is defined and cover the assessment area. Every corners of the grid squares become measurement points where one measurement of at least 10 minutes duration will be done at least 26 times a year. The field inspection methods will depend on the objectives aimed. The analyzed results of this whole procedure give information about the odour dispersion, odour plume and can be used for the validation of dispersion models and draw odour maps.

This guideline gives complete information about the determination of odorants in ambient air by field inspections. The procedures are well presented however no information where available about the reproducibility of the results. This test gives information about odour and other investigation should be done if the odorant composition has to be done to determine the presence of certain gases.

Two Options for Manure Treatment to Reduce Ammonia Emission from Pig Housing

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The aeration system doesn’t prevent N losses under other form (N2 and NO2) unless the nitrification denitrification process is done thoroughly. For biological treatment, the aeration is very costly in term of energy requirements as oxidation is done on degradable material. Acidification is also expensive and organic acids have to be considered in order to be biologically degradable. Caution has to be done for the fertilization for some crops.

Abstractions and Runoff from Fescue Plots Receiving Poultry Litter and Swine Manure

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Dietary Factors Affecting Protein Digestibility in Pigs

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The factors that affect its digestibility have to be better investigated such as role of non starch polysaccharides, antinutritionnal factors and finally other dietary components such as fat level, starch source and mineral content. More work has also to be done to develop alternative ways to improve digestibility such as plant breeding, preservation of feedstuffs, feedstuffs and processing and also the enhancement of digestive functions (effect of enzymes, probiotics).

Finite Element Modelingof Soil Compaction by Liquid Manure Spreaders

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To lower the soil compaction induced by the passage of manure spreaders, decreasing the inflation pressure of the tires to the minimum value recommended by the manufacturer seems to be a valid approach that could reduce soil compaction by almost 10%. For Quebec’s soil conditions and climate and in order to minimize soil compaction, spreaders with conventional tandem bogie running gear used should not exceed a capacity of 13,7 cubic meters.

Microbial Processes in Deep-litter Systems for Fattening Pigs and Emission of Ammonia, Nitrous Oxide and Nitric Oxide.

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The total nitrogen emissions as NH3, NO and N2O were greater for both deep litter systems compared to traditional. Optimum condition are difficult to obtain (moisture, oxygen transfer, bed temperature, microbial activity).

Ammonia Volatilization from Liquid Hog Manure: Influence of Aeration and Trapping Systems

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A Model to Describe the Effect of Nutrition on Growth, Body Composition and Nitrogen Excretion in Pigs

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All the different relations used to build the model are presented. However no results simulation results are presented to compare with what happen in real situations.