The effect of lead on immune and viral interferon production.

Female BDF1 mice were exposed to lead acetate in the drinking water at concentrations ranging form 0 to 1000 micrograms/mL lead for three weeks. The mice tolerated these levels of lead exposure without exhibiting signs of clinical toxicity. Weight gains were not affected by lead exposure. The production of viral interferon induced by the oral administration of tilorone was not altered by lead exposure. The T-lymphocyte mitogens concanavalin A, phytohemagglutinin and staphylococcal enterotoxin A induced immune interferon to varying degrees, with concanavalin A and staphylococcal enterotoxin A exhibiting the most potent induction capabilities. The production of immune interferon induced by T-lymphocyte mitogens was not suppressed by lead exposure.     

Investigation of Caval Syndrome in Dogs Experimentally Infected With Dirofilaria immitis

Nine of 16 dogs inoculated with 200 infective heartworm larvae developed caval syndrome (CS) of heartworm disease (HWD). There was no difference between dogs that did and did not develop CS with regard to total heartworm burden, burden relative to body weight, or female heartworm burden, indicating that factors other than worm mass are involved in the pathogenesis of CS. Male dogs were twice as frequently affected as females, although this finding was not statistically significant. Dogs afflicted with CS exhibited radiographic, pathologic, and hemodynamic evidence of chronic HWD. In a model of single heartworm exposure, these findings strongly support the theory that CS develops due to retrograde migration of adult worms from the pulmonary arteries and right ventricle to the right atrium and venae cavae. Pulmonary artery pressures were dramatically and significantly greater in dogs with CS (60 +/- 18 torr) as compared to non-CS (30 +/- 4 torr) dogs with equal worm burdens.     

The contribution of different groups of foodstuffs to the intake of dietary fibre

The intake of Dietary Fibre (which is defined as the sum of lignin and the polysaccharides not hydrolysed by the endogenous secretions of the human digestive tract) is derived from the plant cell walls in the diet and other non-structural polysaccharides either present naturally in foods, or derived from polysaccharide food additives such as gums or algal polysaccharides. The composition of this complex mixture, its chemical and physical properties, and therefore, the physiological effects associated with its ingestion, will vary according to the foods making up in the diet. While techniques for the measurement and characterisation of dietary fibre still call for a considerable amount of methodological development it is possible to obtain reliable estimates for the major components and the overall composition of these components. These show that in fruits and vegetables the total dietary fibre content (on a fresh weight basis) lies between 2 and 5 g/100 g with peas and beans being an exception in having higher contents. The dietary fibre in cereals varies with the cereal and the reate of extraction used; for example, wholemeal wheat flours contain between 12 and 15 g/100 g whereas white wheat flour (72% extraction) contains between 3 and 4 g/100 g. Wheat bran and related products have much higher contents. The proportion of the dietary fibre present as cellulose does not show great variablility but lignin is extremely variable. Fruits and vegetables contain very small amounts of lignin unless they have lignified seeds or special lignified tissues. The non-cellulosic polysaccharides of fruits and vegetables are characteristically rich in uronic acids (from pectic substances) and arabino-galactans. In cereals β-glucans and arabino-xylans predominate and wheat bran and wholemeal wheat and rye flours are particularly rich in arabino-xylans. The amounds and composition of the dietary fibre in foods commonly forming the diet eaten in the United Kingdom will be reviewed and their contribution to the diet as a whole will be discussed. Changes in the pattern of food consumption in the United Kingdom in the past century will be discussed in relation to the effects that these have had on the consumption of dietary fibre.     

Equilibrative nucleoside transporter 3 deficiency perturbs lysosome function and macrophage homeostasis

Lysosomal storage diseases (LSDs) are a group of heterogeneous disorders caused by defects in lysosomal enzymes or transporters, resulting in accumulation of undegraded macromolecules or metabolites. Macrophage numbers are expanded in several LSDs, leading to histiocytosis of unknown pathophysiology. Here, we found that mice lacking the equilibrative nucleoside transporter 3 (ENT3) developed a spontaneous and progressive macrophage-dominated histiocytosis. In the absence of ENT3, defective apoptotic cell clearance led to lysosomal nucleoside buildup, elevated intralysosomal pH, and altered macrophage function. The macrophage accumulation was partly due to increased macrophage colony-stimulating factor and receptor expression and signaling secondary to the lysosomal defects. These studies suggest a cellular and molecular basis for the development of histiocytosis in several human syndromes associated with ENT3 mutations and potentially other LSDs.     

A Burkholderia pseudomallei toxin inhibits helicase activity of translation factor eIF4A

The structure of BPSL1549, a protein of unknown function from Burkholderia pseudomallei, reveals a similarity to Escherichia coli cytotoxic necrotizing factor 1. We found that BPSL1549 acted as a potent cytotoxin against eukaryotic cells and was lethal when administered to mice. Expression levels of bpsl1549 correlate with conditions expected to promote or suppress pathogenicity. BPSL1549 promotes deamidation of glutamine-339 of the translation initiation factor eIF4A, abolishing its helicase activity and inhibiting translation. We propose to name BPSL1549 Burkholderia lethal factor 1.     

Spatial and Temporal Variability of Sorghum Grain Yield: Influence of Soil,Water, Pests,and Diseases Relationships

This study was conducted to determine relationships between biotic and abiotic factors and to generate information needed to improve the management of site-specific farming (SSF). The effects of water (80% evapotranspiration (ET) and 50% ET), hybrid (drought-tolerant and -susceptible), elevation, soil texture, soil NO₃--N, soil pH, and greenbugs (Schizaphis graminum) (Gb) on sorghum grain yield were investigated at Halfway, TX on geo-referenced locations on a 30-m grid in 1997, 1998, and 1999. Grain yields were influenced by interrelationships among many factors. Grain yields were consistently high under 80% ET treatment and in the upper slopes where the clay and silt fractions of the soil were high. Soil NO₃--N, rainfall, hybrid, and Gb effects on grain yields were seasonally unstable. Soil NO₃--N increased grain yield when water was abundant and depressed grain yields when water was limiting. Plant density effects on grain yield were confounded with hybrid responses to drought and Gb infestation. Managing seasonally unstable factors is a major challenge for farmers and better ways to monitor crop growth and diagnose causes of poor plant growth are needed. To improve the management of SSF, effects of the relationships between biotic and abiotic factors on crop yield must be integrated and evaluated as a system. Based on our study, information on seasonally stable factors like elevation and soil texture is useful in identifying management zones for water and fertilizer application. Water and fertilizers management should be complemented by in-season management of seasonally unstable factors like soil NO₃--N, rainfall, hybrid, and Gb effects on grain yield.     

Impact of sampling and storage technique,and duration of storage,on the composition of fresh grass when analysed using near‐infrared reflectance spectroscopy

The objective of this study was to examine the effect of sampling technique (pluck or cut), storage duration (immediate analysis, 24‐h or 48‐h), storage temperature (ambient or chilled) and storage conditions (air present, air excluded or breathable) on the composition of fresh grass sampled from a sward managed to simulate grazing. Treatments were repeated across four sampling dates, with grass samples stored in grip seal bags prior to analysis using near‐infrared reflectance spectroscopy. Grass sampled by ‘pluck’ had a higher crude protein and ME content, and a lower acid detergent fibre (ADF) content, compared to that sampled by ‘cut’. Grass stored for 48 h had a lower water soluble carbohydrate (WSC) and ME content and a higher ADF content than for immediate analysis. Samples stored for 24 h did not differ from immediate analysis. Grass stored at ambient temperature had a lower WSC and ME content compared to immediate analysis. Grass stored under ‘breathable’ conditions had a lower ME content and higher ADF content than immediate analysis or samples stored with air present or air excluded. It is recommended that grass for analysis should be sampled by cutting, stored chilled (4°C) in a sealed bag to minimize exposure to oxygen and analysed within 24 h of harvest.