Novel insights into transmission routes of Mycobacterium avium in pigs and possible implications for human health

Mycobacterium avium infection is a severe condition in humans, whereas pigs are often subclinically infected. Pig carcasses represent a possible source of human infection. Faecal excretion of M. avium was recently demonstrated in experimentally infected pigs, along with detection of M. avium in apparently normal lymph nodes. The present study investigates faecal excretion in naturally infected herds and the presence of live mycobacteria in lymph nodes. Two pig herds (A and B), with a history of sporadically suspected M. avium infection were sampled. Herd B used peat, as opposed to Herd A. Samples from peat, sawdust, drinking water, faeces and lymph nodes were collected. Identification of mycobacteria was performed by 16S rDNA sequencing and PCR. Mycobacterium avium isolates were analysed by Multi-Locus Variable Number of Tandem repeat Analysis (MLVA). Mycobacterium avium subsp. hominissuis was detected in samples of faeces, peat and lymph nodes from Herd B, often with identical MLVA profiles. Additionally, other non-tuberculous mycobacteria (NTM) were found in the same material. The absence of macroscopic lymph node lesions in the presence of M. avium subsp. hominissuis was frequently demonstrated. In Herd A, only one NTM isolate, which proved not to be M. avium, was found. Faeces might facilitate transmission of M. avium subsp. hominissuis between pigs and maintain the infection pressure in herds. The low incidence of macroscopic lesions together with the massive presence of M. avium subsp. hominissuis in lymph nodes from pigs kept on peat raises questions related to animal husbandry, food safety and human health.     

MAGNETIC RESONANCE IMAGING OF PRIMARY AND CONCOMITANT FLEXOR ENTHESOPATHY IN THE CANINE ELBOW

Flexor enthesopathy is a recently recognized elbow disorder in dogs and considered to be an important differential diagnosis for elbow lameness. Primary and concomitant forms of the disease have been previously described and treatments differ for the two forms. The goal of this prospective study was to compare magnetic resonance imaging (MRI) findings for dogs with primary flexor enthesopathy (n = 17), concomitant flexor enthesopathy (n = 23), elbow dysplasia alone (n = 13), and normal elbows (n = 7). Each elbow joint underwent MRI using the same low‐field scanner. Sequences included transverse and sagittal T1‐weighted (before and after IV contrast), transverse and sagittal T2‐weighted, and dorsal STIR. For each elbow, MRI lesions were recorded based on a consensus of two observers unaware of group status. Magnetic resonance imaging lesions involving flexor tendons were found in 100% of clinically affected joints with primary flexor enthesopathy and 96% of clinically affected joints with concomitant flexor enthesopathy. Thickened flexor muscles were the most common lesions, followed by hyperintense tendon signal and contrast enhancement. Irregular, thickened medial humeral epicondyle, edema, and calcified body lesions were less frequently observed. Magnetic resonance imaging characteristics of flexor enthesopathy were not found in normal joints or those affected by elbow dysplasia alone. No significant differences in frequencies and details of individual MRI characteristics were found between primary and concomitant flexor enthesopathy groups. Findings indicated that MRI is a sensitive technique for detection of flexor enthesopathy lesions in dogs, however, MRI characteristics do not allow differentiation of primary versus concomitant forms of the disease.     

COMPUTED TOMOGRAPHY OF CANINE ELBOW JOINTS AFFECTED BY PRIMARY AND CONCOMITANT FLEXOR ENTHESOPATHY

Flexor enthesopathy is an important differential diagnosis for elbow lameness in dogs. The disorder can be a primary cause of elbow lameness or concomitant with other elbow pathology. Since treatment differs for primary and concomitant forms of flexor enthesopathy, a noninvasive method for distinguishing between them is needed. In the current prospective study, computed tomographic (CT) examination was performed before and after IV injection of contrast in 17 dogs with primary flexor enthesopathy, 24 dogs with concomitant flexor enthesopathy, 13 dogs with elbow dysplasia, and seven normal dogs. Dogs were assigned to groups based on results of clinical examination and at least three other imaging modalities. Computed tomographic lesions consistent with flexor enthesopathy were found in all clinically affected joints with primary flexor enthesopathy and in 29 of the 30 clinically affected joints with concomitant flexor enthesopathy. Those lesions were not found in sound elbows or joints affected by elbow dysplasia. Flexor lesions detected in dogs with primary flexor enthesopathy were not significantly different from those detected in dogs with the concomitant form. Findings indicated that CT can be applied to detect flexor enthesopathy, but a distinction between the primary and concomitant forms was not always possible. Authors recommend the use of multiple diagnostic techniques for treatment planning in affected dogs.     

Relativistic spin precession in the double pulsar

The double pulsar PSR J0737-3039A/B consists of two neutron stars in a highly relativistic orbit that displays a roughly 30-second eclipse when pulsar A passes behind pulsar B. Describing this eclipse of pulsar A as due to absorption occurring in the magnetosphere of pulsar B, we successfully used a simple geometric model to characterize the observed changing eclipse morphology and to measure the relativistic precession of pulsar B's spin axis around the total orbital angular momentum. This provides a test of general relativity and alternative theories of gravity in the strong-field regime. Our measured relativistic spin precession rate of 4.77 degrees (-0 degrees .65)(+0 degrees .66) per year (68% confidence level) is consistent with that predicted by general relativity within an uncertainty of 13%.     

Relationships between microbial community structure and soil environmental conditions in a recently burned system

Most wildfires, even the most severe, burn at mixed intensities across a landscape, depending on local fuel loads, fuel moistures, and wind strength and direction. This heterogeneous patchwork of fire effects can influence the patterns of above- and belowground biotic recovery through altered environmental conditions, nutrient availability, and biotic sources for microbial and vegetative re-colonization. We quantified the effects of low- and high-severity fire 14 months post-burn on key environmental variables typically limiting to microbial activity. We characterized the soil microbial community structure through ester-linked fatty acid analysis (EL-FAME) and identified the soil environmental factors that best explain the pattern of microbial community profiles through canonical correspondence analysis (CCA). Low-severity burning caused no change in soil moisture, pH or temperature while high-severity burning caused an increase in soil moisture, temperature, and a decrease in pH levels, relative to the unburned sites. Soil respiration rates were significantly lower in both the low- and high-severity burn sites, relative to unburned sites, likely due to initial root and microbial death. Overall microbial biomass did not change with either low- or high-severity burning, but the microbial community ordination biplots showed separation of communities by fire, and slight separation by fire severity along three axes. This community separation was driven primarily by a decrease in fungal biomarkers (18:2ω6c, 18:3ω6c) with both low- and high-severity fire. Only 23% of the variation in the microbial community distribution could be explained by three environmental variables: soil pH, temperature, and carbon. These results suggest that the microbial communities in both the low- and high-severity burn sites are structurally different from the populations in the unburned sites.     

Dynamics of 13C‐labeled mustard litter (Sinapis alba) in particle‐size and aggregate fractions in an agricultural cropland with high‐ and low‐yield areas

The application of ¹³C‐labeled litter enables to study decomposition processes as well as the allocation of litter‐derived carbon to different soil C pools. ¹³Carbon‐labeled mustard litter was used in order to compare decomposition processes in an agricultural cropland with high‐yield (HY) and low‐yield (LY) areas, the latter being characterized by a finer texture and a lower organic‐C (OC) content. After tracer application, ¹³C concentrations were monitored in topsoil samples in particulate organic matter (POM) and in fine mineral fractions (silt‐ and clay‐sized fractions). After 568 d, approximately 5% and 10% of the initial ¹³C amount were found in POM fractions of LY and HY areas, respectively. Higher amounts were found in POM occluded in aggregates than in free POM. Medium‐term (0.5–2 y) storage of the initial ¹³C in fine silt‐ and clay‐sized fractions amounts to 10% in HY and LY soils, with faster enrichment but also faster disappearance of the ¹³C signal from LY soils. Amounts of 80%–90% of the added ¹³C were mineralized or leached in the observed period. Decomposition of free POM was faster in HY than in LY areas during the first year, but the remaining ¹³C amounts in occluded‐POM fractions were higher in HY soils after 568 d. High‐yield and low‐yield areas showed different ¹³C dynamics in fine mineral fractions. In LY soils, ¹³C amounts and concentrations in mineral‐associated fractions increased within 160 d after application and decreased in the following time period. In HY areas, a significant increase in ¹³C amounts did not occur until after 568 d. The results indicate initially faster decomposition processes in HY than in LY areas due to different soil conditions, such as soil texture and water regime. The higher silt and clay contents of LY areas seem to promote a faster aggregate formation and turnover, leading to a closer contact between POM and mineral surfaces in this area. This favors the OC storage in fine mineral fractions in the medium term. Lower aggregate formation and turnover in the coarser textured HY soil leads to a delayed C stabilization in silt‐ and clay‐sized fractions.