Alpacas fed calcium propionate seem to moderate their energy intake

Alpacas have evolved digestive and metabolic adaptations that enable them to survive in environments where the available feed varies in nutritional quality. Alpacas are thought to derive glucose from the deamination of amino acids in the liver, rather than via the conversion of propionate like true ruminants. Because fibre growth is dependent on the availability of absorbed amino acids, alpacas using amino acids as a source of energy should leave less amino acids available for fibre growth. If alpacas were to obtain glucose from a source of propionate, such as calcium propionate, the dependence on amino acids would be reduced leaving more available for fibre growth. Calcium propionate was added to the ration fed to 32 alpaca wethers, and fibre production was measured to monitor important fibre attributes in response to calcium propionate. Although the diets supplemented with calcium propionate should have provided more energy than the diets without calcium propionate, the metabolisable energy intake of all animals was similar (p = 0.278). It seems that rather than sparing amino acids, the alpacas regulated their energy intake and refused to consume the additional energy offered as calcium propionate. Consequently, they produced less fibre, and the diameter of their fibre was smaller than those alpacas that were not fed calcium propionate. It seems that alpacas rely on their digestive and metabolic adaptations to efficiently obtain and conserve energy for their survival.     

The physiological effects ofheat stress and the role of heat shock proteins in rainbow trout (Oncorhynchus f) red blood cells

The effects of in vitro thermal stress and the potential role ofheat shock proteins in thermoprotection were examined in the nucleated red blood cells (rbcs) of rainbow trout (Oncorhynchusmykiss). Oxygen consumption, a general indicator of cellular metabolism, was maintained in trout rbcs until 30 °C, but was markedly reduce by 35 °C. Subsequent experiments were then conducted which involved exposing rbcs to 30 °C to determine which physiological variables might be compromised by an extendedheat stress. Although this temperature challenge caused an induction of Hsp 70 mRNA, and a significant reduction in the amount of oxygen bound to hemoglobin, carbonic anhydrase (CA) activity was unaffected by an 8 h, 30 °C exposure.heat stress also caused a rise in methemoglobin formation, but the increase in rbc methemoglobin concentration did not appear to be a stimulus for Hsp 70 induction. Rbc oxygen consumption, CA activity and hemoglobin/oxygen binding ability were unaltered when hsp synthesis was inhibited by the translational inhibitor, cycloheximide. These results indicate that hsps do not have a role in protecting rbc metabolism or the function of important rbc proteins, such as hemoglobin and CA. Extended 30 °Cheat stress did cause a significant leakage of potassium from the rbcs, which appeared to be intensified in the presence of cycloheximide. These latter results suggest that hsps may play a limited role in preserving rbc membrane integrity and/or ionoregulatory processes.     

Trace Metals in Soil and Plants Subjected to Strong Chemical Pollution

The total concentrations of ten elements (Ag, As, Co, Cs, Fe, Ir, Ni, Rb, Sb, and Sc) were determined in soil and vegetation samples from the surroundings of a Cu-Ni smelter in Monchegorsk, Northwest Russia, and a background area in Naruska, North Finland. The samples were analysed by epithermal neutron activation analysis (ENAA). Elements emitted from the smelter (Ag, As, Co, Ir, Ni, and Sb) were mostly accumulated in the topsoil. Some elements also appeared to contaminate deeper soil layers. In both soil and vegetation the metal concentrations decreased with increasing distance from the smelter. The most significant contributor to the high concentrations of Fe and Sc near the smelter was probably damaged ground vegetation and subsequent wind erosion. Possibly high geochemical abundance of Fe and Sc may also have been a contributing factor. Concentrations of Cs and Rb in soil and vegetation generally increased with increasing distance from the pollution source. High negative correlations were evident between these elements and the elements emitted from the smelter, suggesting that cation exchange of Cs and Rb by the elements supplied from the smelter was likely occurring in the surface soil.     

Diazomethane derivatization of sulfamethazine: formation of isomeric products

Reaction of 4-amino-N-(4,6-dimethyl-2-pyrimidinyl)benzenesulfonamide (sulfamethazine) with diazomethane yields not only 4-amino-N-(4,6-dimethyl-2-pyrimidinyl)-N-methylbenzenesulfonamide but also 2-(4-aminobenzenesulfonimido)-1,4,6-trimethyl-1,2-dihydro-pyrimidi ne. Yields of the latter compound are highly variable and the compound does not show a response to gas chromatography. Thus, results of gas chromatographic determinations of residues of some sulfa drugs in edible meat tissues may be erroneous when diazomethane derivatization is used.     

Autophagy-dependent viral recognition by plasmacytoid dendritic cells

Plasmacytoid dendritic cells (pDCs) detect viruses in the acidified endosomes by means of Toll-like receptors (TLRs). Yet, pDC responses to certain single-stranded RNA (ssRNA) viruses occur only after live viral infection. We present evidence here that the recognition of such viruses by TLR7 requires transport of cytosolic viral replication intermediates into the lysosome by the process of autophagy. In addition, autophagy was found to be required for the production of interferon-alpha by pDCs. These results support a key role for autophagy in mediating ssRNA virus detection and interferon-alpha secretion by pDCs and suggest that cytosolic replication intermediates of viruses serve as pathogen signatures recognized by TLR7.     

Coordination of early protective immunity to viral infection by regulatory T cells

Suppression of immune responses by regulatory T cells (Tregs) is thought to limit late stages of pathogen-specific immunity as a means of minimizing associated tissue damage. We examined a role for Tregs during mucosal herpes simplex virus infection in mice, and observed an accelerated fatal infection with increased viral loads in the mucosa and central nervous system after ablation of Tregs. Although augmented interferon production was detected in the draining lymph nodes (dLNs) in Treg-deprived mice, it was profoundly reduced at the infection site. This was associated with a delay in the arrival of natural killer cells, dendritic cells, and T cells to the site of infection and a sharp increase in proinflammatory chemokine levels in the dLNs. Our results suggest that Tregs facilitate early protective responses to local viral infection by allowing a timely entry of immune cells into infected tissue.     

Determination of the potential for development of bacterial soft rot of potatoes

A method has been devised for assessing the potential hazard of soft rot development in potatoes. Tubers are placed in a mist chamber at 20 C (68F), a film of water is maintained on the tuber, and the extent of decay is assessed after 5 days. The soft rot potential determined in this way is intended as apractical indication of potential storage hazard, reflecting the overall effect of the various factors leading to bacterial decay. Tubers that had passed through a flume system and a rinsing spray in a commercial packing plant had a greater decay potential, even after passage through a hot-air dryer, than unwashed tubers. Differences in decay potential could be demonstrated between tubers that had been mechanically harvested and loaded into storage bins and those that had been harvested manually. In addition to the effect of mechanical damage and of passage through flumes, the decay potential was probably affected by the inoculum level ofErwinia carotovora. Pectolytic clostidia were also usually present in tubers rotting in mist chambers, and are probably involved in the decay.     

Comparing methods for handling missing values in food-frequency questionnaires and proposing k nearest neighbours imputation: effects on dietary intake in the Norwegian Women and Cancer study (NOWAC)

OBJECTIVE: To investigate item non-response in a postal food-frequency questionnaire (FFQ), and to assess the effect of substituting/imputing missing values on dietary intake levels in the Norwegian Women and Cancer study (NOWAC). We have adapted and probably for the first time applied k nearest neighbours (KNN) imputation to FFQ data. DESIGN: Data from a recent reproducibility study were used. The FFQ was mailed twice (test-retest) about 3 months apart to the same subjects. Missing responses in the test FFQ were imputed using the null value (frequencies = null, amount = smallest), the sample mode, the sample median, KNN, and retest values. SETTING: A methodological substudy of NOWAC, a national population-based cohort. SUBJECTS: A random sample of 2000 women aged 46-75 years was drawn from the cohort in 2002 (response 75%). The imputation methods were compared for 1430 women who completed at least 50% of the test FFQ. RESULTS: We imputed 16% missing values in the overall test data matrix. Compared to null value imputation, the largest differences in estimated dietary intake were seen for KNN, and for food items with a high proportion of missing. Imputation with retest values increased total energy intake, indicating that not all missing values are caused by respondents failing to specify no consumption, and that null value imputation may lead to underestimation and misclassification. CONCLUSION: Missing values in FFQs present a methodological challenge. We encourage the application and evaluation of newer imputation methods, including KNN, which may reduce imputation errors and give more accurate intake estimates.     

Use of folic acid supplements, particularly by low-income and young women: a series of systematic reviews to inform public health policy in the UK

OBJECTIVE: To provide a basis for making recommendations on the potential to improve use of folic acid supplements in the UK, particularly among low-income and young women. DESIGN: Systematic reviews of relevant research from 1989 to May 2006 in Europe, the USA, Canada, Australia and New Zealand. RESULTS: Twenty-six systematic reviews and/or meta-analyses were identified from the wider public health literature, and eighteen studies on the effectiveness of preconception interventions were included. Ninety studies were identified which were directly relevant to folic acid supplement intake. There were factors that are particularly associated with lower rates of use of folic acid supplements. One of the most important of these is the link with unintended pregnancy, followed by age, socio-economic and ethnic group. Integrated campaigns can increase the use of folic acid supplements to some extent. Research trials indicated that: (i) printed resources and the mass media used in isolation are not effective in the longer term; and (ii) health-care-based initiatives can be effective and are more likely to be successful if they include making supplements easily available. CONCLUSIONS: Campaigns and interventions have the potential to exacerbate socio-economic inequalities in folic acid use. One way of addressing this is to include elements that specifically target vulnerable women. To achieve and maintain an effect, they need to be based on good health promotion practice and to be sustained over a long period. However, even high-quality campaigns that increase use result in under half of women in the target group taking supplements.     

Multiplex PCR for specific and robust detection of Xanthomonas campestris pv. musacearum in pure culture and infected plant material

The present study developed a pathovar‐specific PCR for the detection of Xanthomonas campestris pv. musacearum (Xcm), the cause of banana xanthomonas wilt, by amplification of a 265‐bp region of the gene encoding the general secretion pathway protein D (GspD). A distinct DNA fragment of the expected size was amplified from genomic DNA from all of 12 Xcm isolates tested and no amplification of DNA was observed from other xanthomonads or plant‐associated bacteria, including the two closely related species Xanthomonas vasicola pv. holcicola and Xanthomonas axonopodis pv. vasculorum. The Xcm‐specific PCR was successfully multiplexed with internal control primers targeting 16S rDNA for application on DNA from bacterial cultures and with primers targeting plant mitochondrial 26S rDNA for application on DNA extracted from plant material. Diagnostic discrimination of healthy and infected plants was subsequently demonstrated in tests on artificially inoculated screenhouse cultivars of banana and field bananas with and without symptoms sampled from different parts of Uganda. This study therefore demonstrated a robust and specific Xcm diagnostic tool with the added advantage of applying internal PCR controls for direct quality assessment of results.