Antimicrobial use and stewardship practices on Australian beef feedlots.

OBJECTIVE: Improving antimicrobial stewardship in the livestock sector requires an understanding of the motivations for antimicrobial use and the quantities consumed. However,detailed information on antimicrobial use in livestock sectors is lacking. This cross-sectional study aimed to better understand antimicrobial use in the beef feedlot sector in Australia. DESIGN: A self-administered questionnaire asking about antimicrobial use and reasons for use was designed and mailed to beef feedlot operators in Australia. Respondents were asked to report the percentage of animals treated, purpose of use, and disease conditions targeted for 26antimicrobial agents. RESULTS: In total, 83 of 517 (16.1%) beef feedlot operators completed the survey. Monensin (61.0%of respondents) and virginiamycin (19.5%of respondents) were the most commonly reported in-feed antimicrobials. In-feed antimicrobial agents were most frequently used by respondents for treatment of gastrointestinal diseases (52.8%). Antimicrobials were used for growth promotion by 42.1% of respondents, with most (85.7%) reporting the use of ionophores(a group of compounds not used in human medicine). Short-acting penicillin(69.1%), short-acting oxytetracycline, and tulathromycin (both 57.3%) werethe most common injectable antimicrobial agents used. Injectable antimicrobials were most frequently used to treat respiratory (72.3%) and musculoskeletal (67.5%) conditions. CONCLUSION: Overall,the use of antimicrobials was appropriate for the purpose indicated, and there was a strong preference for drugs of low-importance in human medicine. The data described here stand to be a strong influence on the implementation of an antimicrobial stewardship program in the sector.

Definition and drivers of acute traumatic coagulopathy: clinical and experimental investigations.

BACKGROUND: Acute traumatic coagulopathy (ATC) is an impairment of hemostasis that occurs early after injury and is associated with a 4-fold higher mortality, increased transfusion requirements and organ failure. OBJECTIVES: The purpose of the present study was to develop a clinically relevant definition of ATC and understand the etiology of this endogenous coagulopathy. PATIENTS/METHODS: We conducted a retrospective cohort study of trauma patients admitted to five international trauma centers and corroborated our findings in a novel rat model of ATC. Coagulation status on emergency department arrival was correlated with trauma and shock severity, mortality and transfusion requirements. 3646 complete records were available for analysis. RESULTS: Patients arriving with a prothrombin time ratio (PTr) > 1.2 had significantly higher mortality and transfusion requirements than patients with a normal PTr (mortality: 22.7% vs. 7.0%; P < 0.001. Packed red blood cells: 3.5 vs. 1.2 units; P < 0.001. Fresh frozen plasma: 2.1 vs. 0.8 units; P < 0.001). The severity of ATC correlated strongly with the combined degree of injury and shock. The rat model controlled for exogenously induced coagulopathy and mirrored the clinical findings. Significant coagulopathy developed only in animals subjected to both trauma and hemorrhagic shock (PTr: 1.30. APTTr: 1.36; both P < 0.001 compared with sham controls). CONCLUSIONS: ATC develops endogenously in response to a combination of tissue damage and shock. It is associated with increased mortality and transfusion requirements in a dose-dependent manner. When defined by standard clotting times, a PTr > 1.2 should be adopted as a clinically relevant definition of ATC.

Mobile phones, in combination with a computer locator system, improve the response times of emergency medical services in central London.

INTRODUCTION: The aim of this study was to determine whether mobile phones and mobile phone locating devices are associated with improved ambulance response times in central London. PATIENTS AND METHODS: All calls from the London Ambulance Service database since 1999 were analysed. In addition, 100 consecutive patients completed a questionnaire on mobile phone use whilst attending the St Thomas's Hospital Emergency Department in central London. RESULTS: Mobile phone use for emergencies in central London has increased from 4007 (5% of total) calls in January 1999 to 21,585 (29%) in August 2004. Ambulance response times for mobile phone calls were reduced after the introduction of the mobile phone locating system (mean 469 s versus 444 s; P = 0.0195). The proportion of mobile phone calls made from mobile phones for life-threatening emergencies was higher after injury than for medical emergencies (41% versus 16%, P = 0.0063). Of patients transported to the accident and emergency department by ambulance, 44% contacted the ambulance service by mobile phone. Three-quarters of calls made from outside the home or work-place were by mobile phone and 72% of patients indicated that it would have taken longer to contact the emergency services if they had not used a mobile. CONCLUSIONS: Since the introduction of the mobile phone locating system, there has been an improvement in ambulance response times. Mobile locating systems in urban areas across the UK may lead to faster response times and, potentially, improved patient outcomes.

The relationship between job strain and coronary heart disease: evidence from an english sample of the working male population.

BACKGROUND: Many, but not all, studies have reported that job strain is related to cardiovascular morbidity and mortality. To date, this relationship has not been tested on an English full population sample. This study examines whether the demand-control model of job strain contributes to our understanding of the determinants of coronary heart disease. METHODS: The analysis uses data from 4350 working men aged 20-64 in the 1993 Health Survey for England. Job demand and control characteristics were determined by questionnaire. Several health outcomes were examined: self-rated health; psychiatric health; angina and possible myocardial infarction, measured by the Rose questionnaire; doctor-diagnosed heart disease; any heart disease. The relationship between job strain and the health outcomes was determined by logistic regression analyses after controlling for known confounders. RESULTS: Those in high strain jobs consistently reported poorer health on all measures than men with lower strain. Similarly, men reporting low job strain were least likely to report poor health in 5/6 health outcomes. Those with intermediate levels of strain tended to have intermediate prevalence rates for poor health. The pattern of association between job strain and the CHD was independent of coronary risk factors. CONCLUSIONS: The analyses broadly support Karasek's demand-control model of job strain. Health selection into low strain jobs may account for the lack of an association between job strain and doctor diagnosed heart disease while independent associations between job strain and all CHD measures considered together indicate that job strain may have aetiological significance for heart disease.

Sildenafil citrate on nitrergic transmission in anococcygeus muscles from the urogenital system of male and female mice.

The effects of sildenafil on nitrergic relaxations were compared in anococcygeus muscles from male and female mice. In muscles from both sexes, sildenafil (10-300 nM) produced a weak, direct relaxation of carbachol-induced tone, and increased both the amplitude and duration of nitrergic relaxations. The most marked effect was on nitrergic duration (300-400% increase with 300 nM sildenafil); no differences in potency were observed between male (EC(50), 30 nM) and female (EC(50), 25 nM). The rate of onset for potentiation of nitrergic duration was similar in both sexes; but, on washout, the effects of sildenafil declined more slowly in the male muscle. Relaxations to both nitric oxide (NO) and sodium nitroprusside were also increased in amplitude and duration by 50 nM sildenafil, while those to forskolin and papaverine were unaffected. The results demonstrate that sildenafil causes a similar, potent and selective potentiation of nitrergic transmission in urogenital smooth muscle from both male and female mice.

Signalling from TPA to MAP kinase requires protein kinase C, raf and MEK: reconstitution of the signalling pathway in vitro.

The phorbol ester PMA/TPA (phorbol 12-myristate 13-acetate) is a potent tumor promoter which mimics distinct intracellular signalling events triggered by activated growth factor receptors, e.g. the activation of MAP kinases. The largest known family of TPA-binding proteins comprise members of the protein kinase C (PKC) family although other TPA-binding proteins outside the PKC family have recently been identified. In this report we addressed the mechanism and the pathway by which TPA induces the activation of MAPkinases. Using recombinant proteins and in vitro phosphorylation reactions we identified the components in the signal transduction pathway from TPA to MAPkinase and we show that the activation of MAPkinase by TPA requires the presence of protein kinase C, c-raf and the MAPkinase activator MEK. We also find that the activation of raf autophosphorylation in vitro correlates with the ability of Raf to signal to MAPkinase. Thus the activation of Raf by PKC apparently can trigger the same signalling pathway as oncogenic Raf or Raf activation by ras in combination with tyrosine phosphorylation.

Mezerein and 12-deoxyphorbol 13-isobutyrate, protein kinase C ligands with differential biological activities, do not distinguish PKC-isotypes alpha, beta 1, beta 2, and gamma.

Previous in vitro experiments have shown that the phorbol-like diterpenes 12-deoxyphorbol 13-isobutyrate (dPB), and possibly mezerein, have multiple biological target sites which differ from one another in apparent affinity for dPB by 12.5-780 fold and for mezerein by 24-fold. These two compounds are thus very important ligands because of their potential PKC isotype-selectivity. In the present study they were found to have binding affinities differing by a maximum of only 1.6-fold among recombinant protein kinase C (PKC) isotypes alpha, beta 1, beta 2, and gamma (the "A-group") in a [3H]phorbol dibutyrate binding assay. The apparent Ki's were 92-140 nM for dPB and 68-92 nM for mezerein. Our results are consistent with short-term 12-deoxyphorbol ester-induced mouse skin inflammation being mediated at least in part by one or more A-group PKC isotypes. The data also indicate that the pharmacologically distinguishable target sites previously established for mezerein and dPB must include one or more binding sites not found in the A-group of PKC isotypes and that mezerein has a high-affinity, non-A-group target site in brain.

Activation of the c-Raf protein kinase by protein kinase C phosphorylation.

The product of the c-raf-1 proto-oncogene is a cytoplasmic serine/threonine protein kinase that appears to be activated in signal transduction from a variety of cell-surface receptors. The mechanism of c-Raf activation upon stimulation of cell-surface receptors is not clear, but there seem to exist multiple pathways of activation which involve tyrosine and/or serine phosphorylation of the c-Raf protein in vivo. The activated state of Raf is reflected in an increased apparent molecular weight of the Raf protein in sodium dodecyl sulfate-polyacrylamide gels owing to hyperphosphorylation. The tumor promoter 12-O-tetradecanoyl phorbol 13-acetate (TPA) is one of the agents able to induce this hyperphosphorylation of Raf in vivo, suggesting that protein kinase C (PKC) may be involved in the activation of c-Raf in particular situations. Using recombinant baculoviruses expressing PKC and Raf polypeptides, we show here that conventional PKC types (alpha, beta, gamma) but not novel types (delta, zeta, eta) or the unrelated Mos kinase are able to activate c-Raf in a TPA-dependent manner upon coexpression in insect cells. Direct phosphorylation of the Raf protein with PKC in vitro also enhanced the kinase activity of c-Raf, suggesting that c-Raf acts immediately downstream of PKC in a protein kinase cascade which is triggered by TPA and may lead to transcriptional activation of TPA-inducible genes and tumor promotion.

Protein kinase C group B members PKC-delta, -epsilon, -zeta and PKC-L(eta). Comparison of properties of recombinant proteins in vitro and in vivo.

Of the recently identified protein kinase C (PKC) types of group B (delta, epsilon, zeta, eta, PKC-L), only PKC-epsilon has been characterized in great detail. In order to compare the regulatory and catalytic properties of these new kinases, we have expressed PKC-delta, -epsilon, -zeta and PKC-L as recombinant proteins from their cDNAs in insect cells via baculovirus vectors and in mammalian COS-1 cells. After expression in insect cells, phorbol ester binding and kinase activities of the group B enzymes were compared with the respective activities of a member of group A, PKC-gamma. Although PKC-delta and PKC-L(eta) bind phorbol ester to a similar or the same extent as PKC-gamma, they show a distinctively different behaviour towards conventional PKC substrates such as histone, myelin basic protein, protamine and protamine sulphate, suggesting either that phorbol esters are not able to fully activate these enzymes or that their substrate specificities are very different from those of the group A enzymes. PKC-zeta, a polypeptide of 80 kDa, does not bind phorbol ester and does not phosphorylate these substrates to a significant extent. Consistent with their ability to bind phorbol ester, recombinant PKC-delta and PKC-epsilon are down-regulated in COS cells by prolonged treatment with phorbol ester, whereas PKC-zeta protein levels remain unaltered.

Expression of a pheromone-binding protein in insect cells using a baculovirus vector.

A cDNA encoding a pheromone-binding protein from the male silkmoth Antheraea pernyi has been integrated into the genome of the Autographa californica multiple nuclear polyhydrosis virus such that the transcription was under the control of the strong polyhedrin promoter. Recombinant pheromone-binding protein was expressed in a baculovirus-infected insect cell line (Sf9) and secreted from the cells into the culture medium. Using a two-step protocol, recombinant pheromone-binding protein has been isolated and purified to homogeneity. Pheromone binding of recombinant protein has been demonstrated using a tritiated analog of (E,Z)-6,11-hexadecadienyl acetate.