Accelerated Calvarial Healing in Mice Lacking Toll-Like Receptor 4

The bone and immune systems are closely interconnected. The immediate inflammatory response after fracture is known to trigger a healing cascade which plays an important role in bone repair. Toll-like receptor 4 (TLR4) is a member of a highly conserved receptor family and is a critical activator of the innate immune response after tissue injury. TLR4 signaling has been shown to regulate the systemic inflammatory response induced by exposed bone components during long-bone fracture. Here we tested the hypothesis that TLR4 activation affects the healing of calvarial defects. A 1.8 mm diameter calvarial defect was created in wild-type (WT) and TLR4 knockout (TLR4-/-) mice. Bone healing was tested using radiographic, histologic and gene expression analyses. Radiographic and histomorphometric analyses revealed that calvarial healing was accelerated in TLR4-/- mice. More bone was observed in TLR4-/- mice compared to WT mice at postoperative days 7 and 14, although comparable healing was achieved in both groups by day 21. Bone remodeling was detected in both groups on postoperative day 28. In TLR4-/- mice compared to WT mice, gene expression analysis revealed that higher expression levels of IL-1β, IL-6, TNF-α,TGF-β1, TGF-β3, PDGF and RANKL and lower expression level of RANK were detected at earlier time points (≤ postoperative 4 days); while higher expression levels of IL-1β and lower expression levels of VEGF, RANK, RANKL and OPG were detected at late time points (> postoperative 4 days). This study provides evidence of accelerated bone healing in TLR4-/- mice with earlier and higher expression of inflammatory cytokines and with increased osteoclastic activity. Further work is required to determine if this is due to inflammation driven by TLR4 activation. © 2012 Wang et al

Antimicrobial resistance patterns of Campylobacter from feedlot cattle

Aims: This study examined 448 Campylobacter strains isolated in 1999 and 2000 from US feedlot cattle for resistance to 12 antimicrobials. Methods and Results: Isolates were tested for antimicrobial susceptibility using the E-test method. Approximately 60% (n = 267) were resistant to one or more antimicrobials, and 19·6% (n = 88) were resistant to two or more antimicrobials. Of the Campylobacter jejuni isolates, 49·1% (n = 187) were resistant to tetracycline, 10·2% (n = 39) were resistant to nalidixic acid, 8·4% were resistant to trimethoprim/sulfamethoxazole, and 1·8% (n = 7) were resistant to ciprofloxacin. Resistance to any of the other eight antimicrobials was 1·3% or less, but 14·4% (n = 55) were resistant to two or more antimicrobials. In the Campylobacter coli group, 65·7% (n = 44) were resistant to tetracycline, 52·2% (n = 35) were resistant to trimethoprim/sulfamethoxazole, 22·4% (n = 15) were resistant to nalidixic acid, and 9·0% (n = 6) were resistant to ciprofloxacin. Resistance to any of the remaining eight antimicrobials was 3·0% or less, although 49·3% (n = 33) were resistant to two or more antimicrobials. Conclusions: Although antimicrobials are widely used in US feedlot cattle production, our results demonstrate generally low levels of resistance to a broad range of commonly used antimicrobials relative to other recent studies. Significance and Impact of the Study: Resistance data on Campylobacter isolated from this major US livestock commodity is lacking. This overview enhances current knowledge and provides a basis for further studies

Antimicrobial resistance patterns of Campylobacter from feedlot cattle

Aims: This study examined 448 Campylobacter strains isolated in 1999 and 2000 from US feedlot cattle for resistance to 12 antimicrobials. Methods and Results: Isolates were tested for antimicrobial susceptibility using the E-test method. Approximately 60% (n = 267) were resistant to one or more antimicrobials, and 19·6% (n = 88) were resistant to two or more antimicrobials. Of the Campylobacter jejuni isolates, 49·1% (n = 187) were resistant to tetracycline, 10·2% (n = 39) were resistant to nalidixic acid, 8·4% were resistant to trimethoprim/sulfamethoxazole, and 1·8% (n = 7) were resistant to ciprofloxacin. Resistance to any of the other eight antimicrobials was 1·3% or less, but 14·4% (n = 55) were resistant to two or more antimicrobials. In the Campylobacter coli group, 65·7% (n = 44) were resistant to tetracycline, 52·2% (n = 35) were resistant to trimethoprim/sulfamethoxazole, 22·4% (n = 15) were resistant to nalidixic acid, and 9·0% (n = 6) were resistant to ciprofloxacin. Resistance to any of the remaining eight antimicrobials was 3·0% or less, although 49·3% (n = 33) were resistant to two or more antimicrobials. Conclusions: Although antimicrobials are widely used in US feedlot cattle production, our results demonstrate generally low levels of resistance to a broad range of commonly used antimicrobials relative to other recent studies. Significance and Impact of the Study: Resistance data on Campylobacter isolated from this major US livestock commodity is lacking. This overview enhances current knowledge and provides a basis for further studies

USDA Multi-Agency Project: Collaboration in Animal Health, Food Safety & Epidemiology (CAHFSE)

Despite producer interventions, on-going research and continued surveillance, food borne outbreaks continue and multiple antimicrobial resistant bacteria have emerged. A multi-agency APublic Health Action Plan to Combat Antimicrobial Resistance@ was developed to address these concerns and one USDA response was the development of the Collaboration in Animal Health, Food Safety and Epidemiology (CAHFSE), a partnership among the Agriculture Research Service (ARS), Animal and Plant Health Inspection Service (APHIS), and Food Safety Inspection Service (FSIS. The objective of CAHFSE is to implement and expand a surveillance system patterned after the APHIS National Animal Health Monitoring System (NAHMS) which focuses on animal health and food safety. Swine is the first commodity in CAHFSE. To date, fecal samples from 8 farms have been collected and processed for culture of Salmonella, Campylobacter, Enterococci and E. coli. Preliminary results indicate that all four bacteria have been recovered from a number of operations and are currently being characterized

Repeated observations on the Salmonella culture status of midwest U.S. herds

Mesenteric lymph nodes were collected from pigs from 115 Midwest U.S. swine herds at slaughter on two occasions separated by 6-9 months. These herds were sampled up to three additional times during a three-year period, with 30 herds sampled five times. Thirty pigs were sampled at each collection. Herds were categorized positive if one or more samples revealed Salmonella spp. While culture status at collection one was associated with the second sampling collection (p \u3c 0.01), the association was only moderate in strength (OR = 2.6). Herds with three consecutive positive tests (9 of 38) were all positive on sample four. Prevalence estimates were weakly or not correlated between samplings. In conclusion, Salmonella culture status of these swine herds was weakly predictive of future culture results. Accurate description of Salmonella status based on bacterial culture appears to require repeated or ongoing testing

The Carnot Cycle for Small Systems: Irreversibility and the Cost of Operations

We employ the recently developed framework of the energetics of stochastic processes (called `stochastic energetics'), to re-analyze the Carnot cycle in detail, taking account of fluctuations, without taking the thermodynamic limit. We find that both processes of connection to and disconnection from heat baths and adiabatic processes that cause distortion of the energy distribution are sources of inevitable irreversibility within the cycle. Also, the so-called null-recurrence property of the cumulative efficiency of energy conversion over many cycles and the irreversible property of isolated, purely mechanical processes under external `macroscopic' operations are discussed in relation to the impossibility of a perpetual machine, or Maxwell's demon.Comment: 11 pages with 3 figures. Resubmitted to Physical Review E. Many paragraphs have been modifie

Antimicrobial resistance patterns of Salmonella isolates collected from slaughter age pigs

Salmonellae are ubiquitous in nature and are recovered from many animal species including swine. However, prevalence of specific serotypes can vary. Although carriage is often observed, fecal shedding can be sporadic (2). Salmonella, as well as other food borne pathogens, can be transferred from animals to the human population. However, since the federally mandated HACCP program has been implemented, a reduction in Salmonella among the major food animals has been observed

Investigations into the infection-contamination-infection cycle of zoonotic Salmonella on swine farms: Serovar and sensitivity patterns of Salmonella isolates from animals and environments from selected Minnesota swine farms

Approximately 12000 samples (5400 ileocecal lymph nodes from slaughter pigs and 6600 diverse environmental material such as feces. feed, dust, soil and water from swine farms) have been cultured for Salmonella since 1997 in the framework of the long-term research project Salmonella Abatement in the Pork Chain at the University of Minnesota

Use of Defined Competitive Exclusion Cultures to Enhance Colonization Resistance to Enteric Pathogens

During the past several years our laboratory has conducted research towards developing defined competitive exclusion cultures that enhance colonization resistance against salmonellae in baby chicks. Previously in our laboratory it was shown that 10-day-old broiler and layer chicks that were fed diets containing 5-10% lactose provided either in the feed or in water from day-of-hatch were significantly more resistant to Salmonella typhimurium, and S. enteritidis cecal colonization than control chicks not provided a diet supplemented with lactose. Additionally, resistance against salmonellae cecal colonization was further enhanced in treatment groups provided dietary lactose in combination with an undefined mixture of anaerobic bacteria (i.e. undefined competitive exclusion culture or Nurmi culture) originally obtained from the ceca of adult broiler chickens maintained on a diet containing lactose. In order to make a defined competitive exclusion culture that was efficacious in enhancing colonization resistance against salmonellae, we cultured cecal contents obtained from adult broilers maintained on a unmedicated diet containing 5% lactose in a continuous-flow (CF) culture apparatus (i.e. chemostat), that was maintained at parameters that would best represent the cecal environment