Noble gases in stratospheric dust particles: confirmation of extraterrestrial origin

Noble gas elemental and isotopic ratios were measured in a group of 13 "chondritic" stratospheric dust particles. Neon and argon are present in "solar" proportions; xenon appears to be dominated by contributions from "planetary" sources. The apparent xenon concentration is higher than that measured in any bulk meteorite, approaching the concentration found in the noble gas-rich, acid-insoluble residues from carbonaceous chondrites.     

Dietary patterns in middle-aged Irish men and women defined by cluster analysis

OBJECTIVES: To identify and characterise dietary patterns in a middle-aged Irish population sample and study associations between these patterns, sociodemographic and anthropometric variables and major risk factors for cardiovascular disease. DESIGN: A cross-sectional study. SUBJECTS AND METHODS: A group of 1473 men and women were sampled from 17 general practice lists in the South of Ireland. A total of 1018 attended for screening, with a response rate of 69%. Participants completed a detailed health and lifestyle questionnaire and provided a fasting blood sample for glucose, lipids and homocysteine. Dietary intake was assessed using a standard food-frequency questionnaire adapted for use in the Irish population. The food-frequency questionnaire was a modification of that used in the UK arm of the European Prospective Investigation into Cancer study, which was based on that used in the US Nurses' Health Study. Dietary patterns were assessed primarily by K-means cluster analysis, following initial principal components analysis to identify the seeds. RESULTS: Three dietary patterns were identified. These clusters corresponded to a traditional Irish diet, a prudent diet and a diet characterised by high consumption of alcoholic drinks and convenience foods. Cluster 1 (Traditional Diet) had the highest intakes of saturated fat (SFA), monounsaturated fat (MUFA) and percentage of total energy from fat, and the lowest polyunsaturated fat (PUFA) intake and ratio of polyunsaturated to saturated fat (P:S). Cluster 2 (Prudent Diet) was characterised by significantly higher intakes of fibre, PUFA, P:S ratio and antioxidant vitamins (vitamins C and E), and lower intakes of total fat, MUFA, SFA and cholesterol. Cluster 3 (Alcohol & Convenience Foods) had the highest intakes of alcohol, protein, cholesterol, vitamin B(12), vitamin B(6), folate, iron, phosphorus, selenium and zinc, and the lowest intakes of PUFA, vitamin A and antioxidant vitamins (vitamins C and E). There were significant differences between clusters in gender distribution, smoking status, physical activity, body mass index, waist circumference and serum homocysteine concentrations. CONCLUSION: In this general population sample, cluster analysis methods yielded two major dietary patterns: prudent and traditional. The prudent dietary pattern is associated with other health-seeking behaviours. Study of dietary patterns will help elucidate links between diet and disease and contribute to the development of healthy eating guidelines for health promotion.     

Spatial relationship between Mycobacterium bovis strains in cattle and badgers in four areas in Ireland

We investigated whether strains (restriction fragment length polymorphism, RFLP-types) of Mycobacterium bovis isolated from badgers and from cattle clustered among and within four areas in Ireland. The spatial scan test and nearest-neighbor analysis were used as the spatial cluster-detection techniques. In addition, for each of the major strains, associations between the distance to badger setts and the "centroid" of the cattle farm were assessed in a logistic model. Overall, between September 1997 and May 2000, 316 and 287 M. bovis samples, from badgers and cattle, respectively, were strain-typed. The distribution of strains in badgers, and separately in cattle, differed among areas. Within each of the four large areas, badgers and cattle tended to have similar strains; this is consistent with the sharing of M. bovis strains within an area. In more detailed within-area analyses, some spatial clusters of M. bovis strains were detected, separately, in both cattle and badgers. Almost half of the infected badger setts with a specific strain were located outside of the "detected" clusters. There was no association between the number of infected badgers with a specific M. bovis strain within 2 or 5 km distances to cattle herds, and the risk of the same strain in cattle. We speculate about the dynamic nature of badger movements, as an explanation for the absence of more clusters of most of the strains of M. bovis isolated from badgers, and its impact on trying to study transmission of M. bovis between cattle and badger.     

In vitro inhibition of Eimeria tenella invasion by indigenous chicken Lactobacillus species

The aim of this study was to determine the effects of indigenous chicken Lactobacillus species isolates from different parts of the gastrointestinal tract on Eimeria tenella invasion in vitro and to characterise the nature of inhibition, if any. The effects of competitive exclusion, steric interference and bacterial extracellular factors on E. tenella invasion were examined in an MDBK cell model. Several Lactobacillus species were initially isolated from chickens and identified by biochemical characteristics and 16S-rRNA. All Lactobacillus species isolates tested, significantly inhibited E. tenella invasion. Steric interference did not affect parasite invasion. Extracellular metabolic factors secreted by Lactobacillus species isolates into the surrounding media were shown to inhibit parasite invasion and these factors appeared to be heat stable. These results show that the natural microflora of poultry can provide a source of E. tenella-inhibiting Lactobacillus species in vitro, and thus may contribute to the control of Eimeria infection.     

Dry cow therapy with a non-antibiotic intramammary teat seal - a review

: Dry cow antibiotic therapy is used to eliminate existing intramammary infections and to prevent new infections in the dry period. It is implemented as part of a total management system known as the 'Five-Point Plan' for mastitis control. Recent public concerns over the widespread prophylactic use of antibiotics, coupled with an increasing interest in organic farming, have lead to a re-evaluation of the treatment of cows at drying-off. As a result, attention has focussed on the use of novel alternatives to antibiotic therapy at the end of lactation. One such therapy involves the application of a non-antibiotic bismuth-based intramammary teat seal designed for use in cows with low cell counts at the end of lactation. Like the keratin plug that forms naturally in teats of cows that have been dried-off, teat seal forms a physical barrier to invading pathogens. To date, a number of independent studies have shown that teat seal is as effective as traditional dry cow antibiotic products in preventing the occurrence of new infection during the dry period in cows with somatic cell counts of ≤200,000 cells ml-1 at drying-off. This paper reviews the efficacy of teat seal in preventing dry period mastitis in both conventional and organic dairying systems.     

Tilmicosin-induced bovine neutrophil apoptosis is cell-specific and downregulates spontaneous LTB4 synthesis without increasing Fas expression

The pathology of bacterial pneumonia, such as seen in the bovine lung infected with Mannheimia haemolytica, is due to pathogen virulence factors and to inflammation initiated by the host. Tilmicosin is a macrolide effective in treating bacterial pneumonia and recent findings suggest that this antibiotic may provide anti-inflammatory benefits by inducing polymorphonuclear neutrophilic leukocyte (PMN) apoptosis. Using an in vitro bovine system, we examined the cell-specificity of tilmicosin, characterized the changes in spontaneous leukotriene B4 (LTB4) synthesis by PMN exposed to the macrolide, and assessed its effects on PMN Fas expression. Previous findings demonstrated that tilmicosin is able to induce PMN apoptosis. These results were confirmed in this study by the Annexin-V staining of externalized phosphatidylserine and the analysis with flow cytometry. The cell-specificity of tilmicosin was assessed by quantification of apoptosis in bovine PMN, mononuclear leukocytes, monocyte-derived macrophages, endothelial cells, epithelial cells, and fibroblasts cultured with the macrolide. The effect of tilmicosin on spontaneous LTB4 production by PMN was evaluated via an enzyme-linked immunosorbent assay. Finally, the mechanisms of tilmicosin-induced PMN apoptosis were examined by assessing the effects of tilmicosin on surface Fas expression on PMN. Tilmicosin-induced apoptosis was found to be at least partially cell-specific, as PMN were the only cell type tested to die via apoptosis in response to incubation with tilmicosin. PMN incubated with tilmicosin under conditions that induce apoptosis spontaneously produced less LTB4, but did not exhibit altered Fas expression. In conclusion, tilmicosin-induced apoptosis is specific to PMN, inhibits spontaneous LTB4 production, and occurs through a pathway independent of Fas upregulation.     

Evaluation of the effects of ischemic injury and ureteral obstruction on delayed graft function in cats after renal autotransplantation

OBJECTIVE: To determine the relative importance of ischemic injury to delayed graft function (DGF) in cats. STUDY DESIGN: Experimental study. ANIMALS: Six intact female cats. METHODS: Cats had renal autograft transplantation without ureteral transection and reimplantation and a contralateral nephrectomy. Serum creatinine and blood urea nitrogen (BUN) concentrations were measured regularly and abdominal ultrasound was performed before surgery, the day after surgery and twice weekly thereafter. Ultrasound-guided renal biopsy was performed on day 7. Cats were euthanatized on day 21. Histology of the autograft, ureter, bladder, vascular anastomoses sites, and contralateral kidney were performed. Observations were compared with those from an historic group of research cats that had extravesicular ureteroneocystostomy and contralateral nephrectomy. RESULTS: Five cats completed the study. Serum creatinine and BUN concentrations increased after surgery, peaking at 3.2+/-0.8 and 77.6+/-15.9 mg/dL, respectively, 1-2 days after surgery. Serum creatinine concentration returned to the reference interval by 6 days after surgery. BUN gradually decreased in all cats but did not return to the reference interval by study end. Serum creatinine and BUN concentrations were consistently lower but not significantly so (P=.29 and .56, respectively) compared with the historic ureteroneocystostomy group. No ultrasonographic abnormalities or renal biopsy histologic abnormalities were observed. At necropsy, 1 autograft had generalized interstitial fibrosis. CONCLUSION: Harvesting the renal graft and the ischemia before revascularization causes impaired renal function after engraftment. CLINICAL RELEVANCE: The process of harvesting and reimplanting the renal graft can contribute to DGF in cats, independent of ureteral obstruction.     

Infrared spectroscopy of comet 81P/Wild 2 samples returned by Stardust

Infrared spectra of material captured from comet 81P/Wild 2 by the Stardust spacecraft reveal indigenous aliphatic hydrocarbons similar to those in interplanetary dust particles thought to be derived from comets, but with longer chain lengths than those observed in the diffuse interstellar medium. Similarly, the Stardust samples contain abundant amorphous silicates in addition to crystalline silicates such as olivine and pyroxene. The presence of crystalline silicates in Wild 2 is consistent with mixing of solar system and interstellar matter. No hydrous silicates or carbonate minerals were detected, which suggests a lack of aqueous processing of Wild 2 dust.     

Organics captured from comet 81P/Wild 2 by the Stardust spacecraft

Organics found in comet 81P/Wild 2 samples show a heterogeneous and unequilibrated distribution in abundance and composition. Some organics are similar, but not identical, to those in interplanetary dust particles and carbonaceous meteorites. A class of aromatic-poor organic material is also present. The organics are rich in oxygen and nitrogen compared with meteoritic organics. Aromatic compounds are present, but the samples tend to be relatively poorer in aromatics than are meteorites and interplanetary dust particles. The presence of deuterium and nitrogen-15 excesses suggest that some organics have an interstellar/protostellar heritage. Although the variable extent of modification of these materials by impact capture is not yet fully constrained, a diverse suite of organic compounds is present and identifiable within the returned samples.     

Impacts of biodiversity loss escalate through time as redundancy fades

Plant diversity generally promotes biomass production, but how the shape of the response curve changes with time remains unclear. This is a critical knowledge gap because the shape of this relationship indicates the extent to which loss of the first few species will influence biomass production. Using two long-term (≥13 years) biodiversity experiments, we show that the effects of diversity on biomass productivity increased and became less saturating over time. Our analyses suggest that effects of diversity-dependent ecosystem feedbacks and interspecific complementarity accumulate over time, causing high-diversity species combinations that appeared functionally redundant during early years to become more functionally unique through time. Consequently, simplification of diverse ecosystems will likely have greater negative impacts on ecosystem functioning than has been suggested by short-term experiments.