The prevalence of Dichelobacter nodosus in clinically footrot-free sheep flocks: a comparative field study on elimination strategies.

BACKGROUND: Ovine footrot caused by Dichelobacter nodosus (D nodosus) is an infectious disease affecting sheep worldwide. Switzerland plans a nationwide footrot eradication program, based on PCR-testing of interdigital swab samples. The aim of this study was to test for the presence of D nodosus in clinically footrot-free sheep flocks which had been subjected to different treatment strategies, to assess whether they were feasible for the eradication process, especially focussing on antimicrobial flock treatments. Clinical scoring and PCR-results were compared. Ten farms had used hoof bathing and hoof trimming without causing bleeding, ten had used individual treatments and flock vaccines to gain the free status and ten had become free through whole-flock systemic macrolide treatment. For every farm, three risk-based collected pool samples were analysed for the occurrence of virulent and benign D nodosus by PCR detection of aprV2/aprB2. RESULTS: Six flocks from any treatment group tested positive for aprB2 in all pools. Clinical signs were absent at the time of sampling, but some flocks had experienced non-progressive interdigital inflammation previously. Two flocks tested aprV2-positive in the high-risk pool. One of them underwent a progressive footrot outbreak shortly after sampling. Individual retesting indicated, that virulent D nodosus most likely was reintroduced by a recently purchased ram. In the second flock, a ram was tested positive and treated before clinical signs occurred. CONCLUSIONS: All treatment strategies eliminated the causative agent and were found to be suitable for implementation in the PCR-based eradication process. PCR-testing proved to be more sensitive than visual scoring, as it also detected clinically healthy carriers. It will be of benefit as a diagnostic tool in elimination and surveillance programs.

Atomic homodyne detection of continuous-variable entangled twin-atom states.

Historically, the completeness of quantum theory has been questioned using the concept of bipartite continuous-variable entanglement. The non-classical correlations (entanglement) between the two subsystems imply that the observables of one subsystem are determined by the measurement choice on the other, regardless of the distance between the subsystems. Nowadays, continuous-variable entanglement is regarded as an essential resource, allowing for quantum enhanced measurement resolution, the realization of quantum teleportation and quantum memories, or the demonstration of the Einstein-Podolsky-Rosen paradox. These applications rely on techniques to manipulate and detect coherences of quantum fields, the quadratures. Whereas in optics coherent homodyne detection of quadratures is a standard technique, for massive particles a corresponding method was missing. Here we report the realization of an atomic analogue to homodyne detection for the measurement of matter-wave quadratures. The application of this technique to a quantum state produced by spin-changing collisions in a Bose-Einstein condensate reveals continuous-variable entanglement, as well as the twin-atom character of the state. Our results provide a rare example of continuous-variable entanglement of massive particles. The direct detection of atomic quadratures has applications not only in experimental quantum atom optics, but also for the measurement of fields in many-body systems of massive particles.

Quantum-Enhanced Sensing Based on Time Reversal of Nonlinear Dynamics.

We experimentally demonstrate a nonlinear detection scheme exploiting time-reversal dynamics that disentangles continuous variable entangled states for feasible readout. Spin-exchange dynamics of Bose-Einstein condensates is used as the nonlinear mechanism which not only generates entangled states but can also be time reversed by controlled phase imprinting. For demonstration of a quantum-enhanced measurement we construct an active atom SU(1,1) interferometer, where entangled state preparation and nonlinear readout both consist of parametric amplification. This scheme is capable of exhausting the quantum resource by detecting solely mean atom numbers. Controlled nonlinear transformations widen the spectrum of useful entangled states for applied quantum technologies.

Observation of Scaling in the Dynamics of a Strongly Quenched Quantum Gas.

We report on the experimental observation of scaling in the time evolution following a sudden quench into the vicinity of a quantum critical point. The experimental system, a two-component Bose gas with coherent exchange between the constituents, allows for the necessary high level of control of parameters as well as the access to time-resolved spatial correlation functions. The theoretical analysis reveals that when quenching the system close to the critical point, the energy introduced by the quench leads to a short-time evolution exhibiting crossover reminiscent of the finite-temperature critical properties in the system's universality class. Observing the time evolution after a quench represents a paradigm shift in accessing and probing experimentally universal properties close to a quantum critical point and allows in a new way benchmarking of quantum many-body theory with experiments.

Scalable spin squeezing for quantum-enhanced magnetometry with Bose-Einstein condensates.

A major challenge in quantum metrology is the generation of entangled states with a macroscopic atom number. Here, we demonstrate experimentally that atomic squeezing generated via nonlinear dynamics in Bose-Einstein condensates, combined with suitable trap geometries, allows scaling to large ensemble sizes. We achieve a suppression of fluctuations by 5.3(5) dB for 12,300 particles, from which we infer that similar squeezing can be obtained for more than 10(7) atoms. With this resource, we demonstrate quantum-enhanced magnetometry by swapping the squeezed state to magnetically sensitive hyperfine levels that have negligible nonlinearity. We find a quantum-enhanced single-shot sensitivity of 310(47) pT for static magnetic fields in a probe volume as small as 90 µm3.

Accurate atom counting in mesoscopic ensembles.

Many cold atom experiments rely on precise atom number detection, especially in the context of quantum-enhanced metrology where effects at the single particle level are important. Here, we investigate the limits of atom number counting via resonant fluorescence detection for mesoscopic samples of trapped atoms. We characterize the precision of these fluorescence measurements beginning from the single-atom level up to more than one thousand. By investigating the primary noise sources, we obtain single-atom resolution for atom numbers as high as 1200. This capability is an essential prerequisite for future experiments with highly entangled states of mesoscopic atomic ensembles.

Rabi flopping induces spatial demixing dynamics.

We experimentally investigate the mixing and demixing dynamics of Bose-Einstein condensates in the presence of a linear coupling between two internal states. The observed amplitude reduction of the Rabi oscillations can be understood as a result of demixing dynamics of dressed states as experimentally confirmed by reconstructing the spatial profile of dressed state amplitudes. The observations are in quantitative agreement with numerical integration of coupled Gross-Pitaevskii equations without free parameters, which also reveals the criticality of the dynamics on the symmetry of the system. Our observations demonstrate new possibilities for changing effective atomic interactions and studying critical phenomena.

Activation of carcinogens and mutagens by rat colon mucosa.

Colon mucosal cells can catalyze the activation of precarcinogens to mutagenic metabolites without the intermediacy of intestinal bacteria as shown in a mutagenesis assay system composed of Salmonella typhimurium strain TA100 and the 9000 X g supernatant fraction of rat colon mucosal cells. Pretreatment of rats with beta-naphtoflavone increased the activation of 2-aminoanthracene 10- to 20-fold and the activation of benzo(a)pyrene 4-fold. Pretreatment of rats with Aroclor 1254 doubled the activation of 2-aminoanthracene over control but had no effect on the activation of benzo(a)pyrene. The activation of 2-aminoanthracene and benzo(a)pyrene by liver was induced significantly by pretreatment with beta-naphthoflavone and Aroclor 1254. Phenobarbital/hydrocortisone pretreatment did not increase the activation by the colon system of any precarcinogen tested but did increase the activation of 2-aminoanthracene, cyclophosphamide, and isophosphamide by the liver system. The activation of precarcinogens in the bacterial test system is directly correlated with the activities of the pretreated colon and liver preparations toward several drug and polycyclic hydrocarbon substrates assayed in vitro.

Effects of cyclophosphamide and polycyclic aromatic hydrocarbons on cell growth and mixed-function oxidase activity in a human colon tumor cell line.

Human colon tumor cells (cell line LS174T) retain a cytochrome P-450-containing drug metabolism system capable of hydroxylating polycyclic hydrocarbons and the anticancer drug cyclophosphamide. The hydroxylation of benzo(a)pyrene by human colon tumor cells is highly inducible. Phenobarbital plus hydrocortisone induce benzo(a)pyrene hydroxylation activities 10-fold, while benz(a)anthracene induces the rate of hydroxylation 30-fold. Cytochrome P-450 specific content is increased 2- to 3-fold by treatment with phenobarbital plus hydrocortisone and benz(a)anthracene, respectively. Addition of cyclophosphamide alone results in no increase in hydroxylation activities but causes a decrease in cell growth rate. The combination of cyclophosphamide with either of the inducers phenobarbital plus hydrocortisone or benz(a)anthracene results in markedly enhanced inhibition of cell growth as judged both by a decrease in the number of cells per plate and in the incorporation of [3H]thymidine into DNA. Thus, these data show that cyclophosphamide is cytotoxic to human colon tumor cells and that the cytotoxicity is enhanced by simultaneous administration of benz(a)anthracene or phenobarbital plus hydrocortisone to the tissue cultures.

Effects of human bone marrow stroma on the growth of human tumor cells.

As some tumors metastasize frequently to marrow we modified the clonogenic assay for human tumor cell growth by culturing tumor cells in the presence of human bone marrow stromal cells. In a bilayer soft agar assay, human tumor cells which had been passaged in nude mice were plated in the agar overlayer on an underlayer containing a suspension of trypsinized human bone marrow stromal cells. These marrow stromal cells stimulated the growth of tumor cells in a dose-dependent fashion, with a growth peak at a stromal cell density of 5-10 x 10(5)/ml. The maximal stimulation of tumour cell growth was 13-fold. We evaluated clonal growth of six separate tumors of five different histological types (small and large cell bronchogenic carcinoma; mammary carcinoma; malignant melanoma; pleural mesothelioma) and demonstrated that in 9 of 11 experiments tumor cell colonies formed in the absence of stromal cells, but colony growth was markedly stimulated by stromal cells in every case. Stromal stimulation persisted after irradiation of the stromal cells with 10 Gy. Growth of five fresh human tumor samples was similarly stimulated by the presence of human bone marrow stromal cells. Tumor cell colonies were characterized morphologically by Pappenheim stain and immunologically for surface antigens by peroxidase-antiperoxidase immunostaining utilizing monoclonal antibodies (carcinoembryonic antigen 26/3/13 and 26/5/1, EMA, HEA125, Sam 2 and Sam 10) which detected epithelial cell antigens. Colonies consisted of cytologically malignant cells which expressed epithelial cell antigens. Thus, the tumor cell origin of colonies from mammary carcinoma and bronchogenic small cell, large cell, and adenocarcinoma was proven. This tumor stem cell assay permits further analyses of human tumor cell biology and may be useful for testing drug sensitivity.

Preparation of homogeneous NADPH-cytochrome P-450 reductase from rat hepatoma.

NADPH-cytochrome P-450 reductase was purified to homogeneity from hepatoma 5123t.c.(H) microsomes from phenobarbital and hydrocortisone-treated rats by detergent solubilization and affinity chromatography with an overall 8% recovery. The purified enzyme has a minimum subunit molecular weight of 79 000 and contains one molecule each of FMN and FAD per 79 000 molecular weight. The purified hepatoma cytochrome P-450 reductase catalyzes electron transfer to artificial electron acceptors with Km values similar to those of purified liver reductase. The Km value of the hepatoma reductase for NADPH, 13 microM, is also similar to that of purified liver reductase. The tumor reductase appears immunochemically identical to liver reductase by Ouchterlony double-diffusion analysis and inhibition of activity. Peptide maps of the hepatoma and hepatic enzymes after proteolysis demonstrate the identity of the two proteins.

Drug metabolism in the Novikoff hepatoma: evidence for a mixed function oxidase system and partial purification of cytochrome P-450 reductase.

Novikoff kepatoma microsomes catalyze the hydroxylation of benzphetamine and ethylmorphine at rates less than 1% of those of liver microsomes but catalyze the hydroxylation of p-nitroanisole and p-nitrophenetole at rates about 40% of those of liver microsomes. Benzo[a]pyrene hydroxylation is also catalyzed by Novikoff hepatoma microsomes at about 2% of the rate of liver microsomes. Like the hepatic microsomal system the rates of substrate hydroxylation by Novikoff hepatoma microsomes can be increased by pretreatment with phenobarbital/hydrocortisone or beta-naphthoflavone and inhibited by carbon monoxide, SKF-525A, and 7,8-benzoflavone. In addition, NADPH-cytochrome P-450 reductase (NADPH:ferricytochrome oxidoreductase, EC 1.6.2.4) has been partially purified from Novikoff hepatoma ascites cells and some properties are described. The induction and inhibition characteristics of the Novikoff hepatoma microsomal hydroxylation activities and the isolation of a cytochrome P-450 reductase from the hepatoma are consistent with the presence of a functional mixed function oxidase system in the Novikoff hepatoma, analogous to that present in liver endoplasmic reticulum.

Expression of cytochromes P450 4F4 and 4F5 in infection and injury models of inflammation.

Lipopolysaccharide (LPS) treatment of rats suppresses CYP 4F4 and 4F5 expression by 50 and 40%, respectively, in a direct fashion occurring in the liver. This contention is borne out by essentially parallel dose-dependent changes observed upon treatment of rat hepatocyte cultures with LPS. An alternate avenue of triggering the inflammatory cascade is traumatic brain injury by controlled cortical impact. Such injury brings about a dramatic change in the expression of CYP 4F4 and 4F5 mRNA which reaches its greatest effect 24 h after impact compared with sham-operated but uninjured controls. At time points after 24 h the expression of both isoforms increases dramatically reaching highest levels at 2 weeks post-injury. These changes in mRNA expression are mirrored by changes in protein expression. The results are consistent with the notion that immediately after injury concentrations of leukotriene and prostaglandin mediators are elevated by decreased CYP 4F concentrations. As time after injury increases those conditions reverse. Increased CYP 4F expression leads to diminished concentrations of leukotriene and prostaglandin mediators and then to recovery and repair.

[Lavasept as an alternative to PVP-iodine as a preoperative antiseptic in ophthalmic surgery. Randomized, controlled, prospective double-blind trial]. / Lavasept als Alternative für PVP-Iod zur präoperativen Antiseptik in der Ophthalmochirurgie Eine randomisierte, kontrollierte, prospektive Doppelblindstudie.

BACKGROUND: To reduce the risk of endophthalmitis PVP-iodine is typically used preoperatively. Since iodine is contraindicated in patients with a specific allergic history or severe thyroid disorder we studied the effect of Lavasept, which contains Polyhexanid as an antiseptic alternative. PATIENTS AND METHODS: In a randomized controlled double-blind trial 3 drops of 0.2% Lavasept, 1.25% PVP-iodine or Ringer's solution were applied preoperatively to 67 patients, which have had a minimum of 5 colony forming units (cfu's) in the conjunctival swap. The effectiveness and tolerability were measured. RESULTS: After application of Lavasept or PVP-iodine, the number of cfu was statistically significantly reduced. Lavasept reduced the number of bacterial colonies significantly better than PVP-iodine (p=0.05). All test solutions were equally well tolerated. CONCLUSION: The use af Lavasept is safe, well tolerated and reduces the microbiological contamination of the conjunctival fornix effectively. lt provides a more effective reduction of the cfu's than PVP-iodine 1.25% and this effect tends to be prolonged. Lavasept is a good alternative option in ophthalmology for preoperative antisepsis.

[Water requirements, water supply and thermoregulation in small ruminants in pasture-based husbandry systems]. / Wasserbedarf, Wasserversorgung und Thermoregulation kleiner Wiederkäuer bei Weidehaltung.

Water is an essential source of life and is available to animals as free water, water content of feed, film water (e. g. dew) and metabolic water. The water requirements of small ruminants are influenced by the type of feed, climate, stage of production, type and length of the fleece or hair coat, husbandry factors and the general health of the animal. Differences in water metabolism, drinking behaviour and the efficiency of temperature regulation are further influenced by species, breed, production type, husbandry system, acclimatisation and adaptation. Small ruminants have been, and are still predominantly kept in extensive husbandry systems. They are therefore genetically and phenotypically well adapted to these conditions and possess a range of physiological and behavioural mechanisms to deal with adverse and suboptimal weather conditions. Regarding animal welfare, there is considerable debate in the discussion and assessment of what constitutes a sufficient water supply for small ruminants under different husbandry conditions, often involving differences between theoretical demands and practical experience. This publication reviews and summarises the current literature regarding water requirements, water metabolism and thermoregulatory mechanisms of small ruminants to provide the basis for an informed assessment of extensive husbandry systems in terms of compliance with animal-welfare requirements.

Cytochromes P450 in brain: function and significance.

The presence and activity of cytochromes P450 in brain regions and various brain cells have been extended and advanced over the last five years covered by this review. Using in situ hybridization and immunohistochemical techniques, many cytochrome P450 enzymes have been demonstrated to be present in brain and to have a regional rather than universal distribution. Many of these various cytochromes P450 have been shown to catalyze the metabolism of neurosteroids as well as other biologically significant compounds in brain. In addition, many cytochrome P450 enzymes have been implicated in the metabolism of psychoactive drugs such as neuroleptics and antidepressants. The regulation of cytochrome P450 expression has been studied at greater detail, the regulation of aromatase being a prominent example during the last five years.

Inhibition of neuronal nitric oxide synthase by 4-amino pteridine derivatives: structure-activity relationship of antagonists of (6R)-5,6,7,8-tetrahydrobiopterin cofactor.

The family of nitric oxide synthases (NOS) catalyzes the conversion of L-arginine to L-citrulline and nitric oxide (NO), an important cellular messenger molecule which has been implicated in the pathophysiology of septic shock and inflammatory and neurodegenerative disease states. NOS can be maximally activated by the ubiquitous cofactor, (6R)-5,6,7,8-tetrahydrobiopterin (H(4)Bip), and antagonists of H(4)Bip may be of therapeutic importance to inhibit pathologically high NO formation. The 4-amino substituted analogue of H(4)Bip was reported to be a potent NOS inhibitor. Therefore, we developed a series of novel 4-amino pteridine derivatives, anti-pterins, to pharmacologically target the neuronal isoform of nitric oxide synthase (NOS-I). To functionally characterize the pterin/anti-pterin interaction and establish a structure-activity relationship (SAR), we systematically altered the substituents in the 2-, 4-, 5-, 6-, and 7-position of the pteridine nucleus. Varying the substitution pattern in the 2-, 5-, and 7-position resulted in no significant inhibitory effect on enzyme activity. In contrast, bulky substituents in the 6-position, such as phenyl, markedly increased the inhibitory potency of the reduced 4-amino-5,6,7,8-tetrahydropteridines, possibly as a consequence of hydrophobic interactions within NOS-I. However, this was not the case for the aromatic 4-amino pteridines. Interestingly, chemical modification of the 4-amino substituent by dialkyl/diaralkylation together with 6-arylation of the aromatic 2,4-diamino pteridine resulted in potent and efficacious inhibitors of NOS-I, suggesting possible hydrophilic and hydrophobic interactions within NOS-I. This SAR agrees with (a) the recently published crystal structure of the oxygenase domain of the inducible NOS isoform (NOS-II) and (b) the comparative molecular field analysis of selected NOS-I inhibitors, which resulted in a 3D-QSAR model of the pterin binding site interactions. Further optimization should be possible when the full length structure of NOS-I becomes available.

Release of nitric oxide from endothelial cells stimulated by YC-1, an activator of soluble guanylyl cyclase.

1 In this study we examined the endothelium-dependent effect of YC-1 - a benzyl indazole derivative which directly activates soluble guanylyl cyclase (sGC) - on vascular relaxation and nitric oxide (NO) and guanosine-3',5'-cyclic monophosphate (cyclic GMP) in endothelial cells. 2 In preconstricted rat aortic rings with intact endothelium, YC-1 produced a concentration-dependent relaxation. However, the concentration response curve was shifted rightward to higher concentrations of YC-1, when (i) the aortas were pre-treated with L-NG-nitroarginine methylester (L-NAME) or (ii) the endothelium was removed. 3 Incubation of bovine aortic endothelial cells (BAEC) with YC-1 produced a concentration-dependent NO synthesis and release as assessed using a porphyrinic microsensor. Pre-incubating cells with L-NAME or with 8-bromo-cyclic GMP decreased this effect indicating that the YC-1 stimulation of NO synthesis is due to an activation of nitric oxide synthase, but not to an elevation of cyclic GMP. No direct effect of YC-1 on recombinant endothelial constitutive NO synthase activity was observed. 4 The YC-1 stimulated NO release was reduced by 90%, when extracellular free calcium was diminished. 5 In human umbilical vein endothelial cells (HUVEC), YC-1 stimulated intracellular cyclic GMP production in a concentration- and time-dependent manner. Stimulation of cyclic GMP was greater with a maximum concentration of YC-1 compared to calcium ionophore A23187. Similar effects were observed in BAEC and rat microvascular coronary endothelial cells (RMCEC). 6 When HUVEC and RMCEC were pre-treated with L-NG-nitroarginine (L-NOARG), the maximum YC-1 stimulated cyclic GMP increase was reduced by >/=50%. 7 These results indicate, that beside being a direct activator of sGC, YC-1 stimulates a NO-synthesis and release in endothelial cells which is independent of elevation of cyclic GMP but strictly dependent on extracellular calcium. The underlying mechanism needs to be determined further.

Aging affects the drug metabolism systems of rat liver, kidney, colon and lung in a differential fashion.

Microsomes prepared from the liver, lungs, colon and kidney cortex of Sprague Dawley rats of ages 2, 4, 10, 24 and 78 weeks were assessed for hydroxylation activity with the substrate benzo[alpha]pyrene. Liver microsomal activity declined after reaching a peak of activity at 10 weeks. The hydroxylation of benzo[alpha]pyrene by colon, kidney and lung microsomes, however, either remained the same or decreased only slightly. During the age range examined inducibility of hydroxylation activity by beta-naphthoflavone decreased with age in liver but actually increased with age in the extrahepatic tissues. Although phenobarbital did not elicit any increases in liver, kidney or lung, it increased substantially benzo[alpha]pyrene hydroxylation activity in colon microsomes of 78 week old rats. Total cytochrome P-450 content was induced at all age groups in all tissues by beta-naphthoflavone and in all tissues except lung by phenobarbital. Induction of cytochrome P-450 in kidney by phenobarbital was only observed in 24 and 78 week old rats. These data suggest an increased role for extrahepatic activation of benzo[alpha]pyrene with aging. In contrast to total content of cytochrome P-450, the beta-naphthoflavone inducible amount of Form 5 which has a high turnover number for benzo[alpha]pyrene, declined by 55% in liver between 2 weeks and 78 weeks while it increases dramatically in all extrahepatic tissues (from 80 to 138%).

Aging modifies the expression of hepatic microsomal cytochromes P-450 after pretreatment of rats with beta-naphthoflavone or phenobarbital.

The various forms of hepatic cytochrome P-450 respond differentially to aging and induction. We examined the levels of six forms of cytochrome P-450, designated as Forms 1 through 5 and Form b, as a function of age and induction. Radial immunodiffusion analysis of rat liver microsomes indicate that cytochrome P-450 Forms 1 and 2 respond to induction by beta-naphthoflavone or phenobarbital less well in aging rats than in young rats. beta-naphthoflavone is less effective in inducing Forms 3, 4, and 5 in aging rats than in young rats. Phenobarbital, however, is more effective in inducing Forms 3 and 4 in aging rats than in young rats but does not induce Form 5 in either young or aging rats. Although Form b is induced predominantly by phenobarbital, beta-naphthoflavone induces Form b moderately in aging rats. Phenobarbital induces Form b to approximately the same extent in aging rats and in young rats. In untreated rats Form 2 is the predominant form, while Forms 1 and 3 are present in moderate amounts. The results of the immunodiffusion analysis were confirmed by the resolution and partial purification of cytochromes P-450 from microsomes of aging and young rats pretreated with beta-naphthoflavone or phenobarbital. These results identify changes with age in specific forms of cytochrome P-450 as a function of the aging process in rats.