Metal chelate molluscicides: The redistribution of iron diazaalkanolates from the gut lumen of the slug,Deroceras reticulatum (Müller) (Pulmonata: Limacidae)

Two related iron chelates, one toxic to slugs by ingestion, the other not, were introduced into the foregut of D. reticulatum. The subsequent movement and redistribution of the metal within the slug tissues was studied by labelling the chelates with the radioactive isotope ⁵⁵Fe. In slugs which survived treatment approximately half of the ⁵⁵Fe was voided in faeces. The iron retained became unevenly distributed, the highest concentration occurring in the digestive gland, irrespective of the chelate used. At high doses, slugs treated with tris(1-oxo-1,2-diazabutan-2-oxido)Fe(III) were fatally poisoned while those treated with the homologue, tris(1-oxo-1,2-diazaoctan-2-oxido)Fe(III) were not. Slugs killed by the toxic chelate consistently contained proportionally less iron in the digestive gland and proportionally more in the body wall and reproductive system. Dosing slugs already killed by carbon dioxide asphyxiation gave a similar pattern, suggesting that the greater mobility of the iron from the toxic chelate was not a function of the slugs' metabolism.     

Fairness in irrigation development

There is in much of contemporary irrigation development a large paradox. Irrigation development, while contributing to productivity, frequently thwarts social justice—it either introduces incipient inequalities in access or it reinforces those that exist. More progressive irrigation development policies are being developed and tested in several countries. These new approaches give more attention to the role of local groups in governing irrigation systems while reducing the heavy-handed involvement of state agencies. These new approaches are seen as both consistent with achieving greater fairness in irrigation development as well as with the new fiscal realities of governments nearly everywhere. Supporting these new approaches are a set of institutions and individuals with nonengineering expertise who traditionally have not been defined as central to irrigation development.     

An enzyme-linked immunosorbent assay for detection of avian influenza virus subtypes H5 and H7 antibodies

Background

Avian influenza virus (AIV) subtypes H5 and H7 attracts particular attention because of the risk of their potential pathogenicity in poultry. The haemagglutination inhibition (HI) test is widely used as subtype specific test for serological diagnostics despite the laborious nature of this method. However, enzyme-linked immunosorbent assays (ELISAs) are being explored as an alternative test method.H5 and H7 specific monoclonal antibodies were experimentally raised and used in the development of inhibition ELISAs for detection of serological response specifically directed against AIV subtypes H5 and H7. The ELISAs were evaluated with polyclonal chicken anti-AIV antibodies against AIV subtypes: H1N2, H5N2, H5N7, H7N1, H7N7, H9N9, H10N4 and H16N3.

Results

Both the H5 and H7 ELISA proved to have a high sensitivity and specificity and the ELISAs detected H5 and H7 antibodies earlier during experimental infection than the HI test did. The reproducibility of the ELISA’s performed at different times was high with Pearson correlation coefficients of 0.96-0.98.

Conclusions

The ELISAs are a potential alternative to the HI test for screening of large amounts of avian sera, although only experimental sera were tested in this study.     

Operation and maintenance in Asian irrigation: Reappraising government and farmer responsibilities and rights

A major policy concern in irrigation development is reducing government costs of both construction and operation and maintenance. There is increasing interest in shifting some of these costs to the farmers using the irrigation facilities. This paper discusses the opportunities for reducing certain direct costs to government by collaborative arrangements with water users so that the latter mobilize more of their own resources to implement specified O&M activities. Five propositions are discussed which suggest the prerequisites for successful collaboration: (1) reexamining the processes of design and construction now being used, (2) reorienting the policies and procedures of the irrigation agency, (3) increasing farmer involvement in operations, (4) increasing local organizational capacity, and (5) creating new financial procedures.     

Prevalence of Helicobacter pylori infection among Egyptian children: impact of social background and effect on growth

OBJECTIVE: The study aim was to assess the prevalence of Helicobacter pylori infection in Egyptian schoolchildren and its effect on growth parameters. DESIGN: A cross-sectional population-based study was conducted among 286 schoolchildren (168 boys and 118 girls), with a mean age of 11.04 +/- 0.19 years, to determine the prevalence of H. pylori. The presence of the bacterium was assessed using the [13C]urea breath test. Relevant personal and socio-economic data on risk factors for infection were collected. Height and weight were analysed in relation to H. pylori infection. RESULTS: The overall prevalence of H. pylori infection was 72.38%. Attending school in a socially deprived area and residing in an overcrowded home were the major risk factors for infection. Differences between infected and non-infected children were significant with regard to body weight and height (weight: 39.5 +/- 1.0 vs. 44.6 +/- 1.8 kg, P = 0.05; height: 139.9 +/- 1.3 vs. 144.2 +/- 2.1 cm; P = 0.009). The number of children (both boys and girls) falling below the 5th percentile of height-for-age was significantly higher in infected than non-infected children (P = 001), similarly for Z-scores for height-for-age below -2.0 (P = 0.003). CONCLUSION: The results demonstrate not only that the prevalence of H. pylori infection is extremely high among Egyptian schoolchildren, but also that the adverse effects of the infection reach far beyond the stomach. Evidence of the burden of infection on growth failure is presented.