The climateprediction.net BBC climate change experiment: design of the coupled model ensemble

Perturbed physics experiments are among the most comprehensive ways to address uncertainty in climate change forecasts. In these experiments, parameters and parametrizations in atmosphere-ocean general circulation models are perturbed across ranges of uncertainty, and results are compared with observations. In this paper, we describe the largest perturbed physics climate experiment conducted to date, the British Broadcasting Corporation (BBC) climate change experiment, in which the physics of the atmosphere and ocean are changed, and run in conjunction with a forcing ensemble designed to represent uncertainty in past and future forcings, under the A1B Special Report on Emissions Scenarios (SRES) climate change scenario.

Development of brief methods to classify individuals by PROP taster status

The purpose of this study was to develop brief methods for classifying individuals by genetic taste sensitivity to 6-n-propylthiouracil (PROP). Two methods are described, which are modifications of a commonly used, suprathreshold procedure. Eighty-nine adult subjects rated the perceived intensity of solutions of 0.032, 0.32 and 3.2 mmol/l PROP and 0.01, 0.1, 1.0 mol/l sodium chloride (NaCl) (three-solution test), as well as solutions of 0.32 mmol/l PROP and 0.1 mol/l NaCl (one-solution test) using the Labeled Magnitude Scale (LMS). Subjects were classified as PROP nontasters (n=22), medium tasters (n=51) or supertasters (n=16) by the three-solution test. Taster status was independently determined by the one-solution test using numerical cutoff scores, which were determined by calculating the +/-95% confidence interval around the group means for PROP taste intensity. Supertasters gave PROP a rating of > or =51 ("very strong" on the LMS) and nontasters gave PROP a rating of < or =15.5 (approximately "moderate" on the LMS). Medium tasters fell between these two limits. Ninety-one percent of nontasters, 82% of medium tasters and 89% of supertasters were classified in a similar way by the two methods. Agreement between methods was high [coefficient of association (P)=0.74; P < or =.001]. These data suggest that three- and one-solution methods can reliably classify subjects by taste sensitivity to PROP and could provide valuable tools in population-based studies.

Will disruptive innovations cure health care?

It's no secret that health care delivery is convoluted, expensive, and often deeply dissatisfying to consumers. But what is less obvious is that a way out of this crisis exists. Simpler alternatives to expensive care are already here--everything from $5 eyeglasses that people can use to correct their own vision to angioplasty instead of open-heart surgery. Just as the PC replaced the mainframe and the telephone replaced the telegraph operator, disruptive innovations are changing the landscape of health care. Nurse practitioners, general practitioners, and even patients can do things in less-expensive, decentralized settings that could once be performed only by expensive specialists in centralized, inconvenient locations. But established institutions--teaching hospitals, medical schools, insurance companies, and managed care facilities--are fighting these innovations tooth and nail. Instead of embracing change, they're turning the thumbscrews on their old processes--laying off workers, delaying payments, merging, and adding layers of overhead workers. Not only is this at the root of consumer dissatisfaction with the present system, it sows the seeds of its own destruction. The history of disruptive innovations tells us that incumbent institutions will be replaced with ones whose business models are appropriate to the new technologies and markets. Instead of working to preserve the existing systems, regulators, physicians, and pharmaceutical companies need to ask how they can enable more disruptive innovations to emerge. If the natural process of disruption is allowed to proceed, the result will be higher quality, lower cost, more convenient health care for everyone.

Isolation and characterisation of sex-specific transcripts from Oesophagostomum dentatum by RNA arbitrarily-primed PCR

In light of the lack of molecular data on the sexual differentiation, maturation and interaction of parasitic nematodes of livestock, the present study investigated sex-specific gene expression in the nodule worm, Oesophagostomum dentatum (Strongylida). Using the technique of RNA arbitrarily-primed polymerase chain reaction (RAP-PCR), 31 expressed sequence tags (ESTs) differentially-displayed between the sexes were cloned. Northern blot analysis proved ten ESTs to be expressed exclusively in males (adults and fourth-stage larvae), while two were expressed solely in female stages. None of the ESTs were expressed in infective third-stage larvae. Sequence analysis and subsequent database searches revealed two male-specific ESTs to have significant similarity to Caenorhabditis elegans (predicted) proteins, a protein containing an EGF-like cysteine motif and a serine/threonine phosphatase. Another two male-specific ESTs had similarity to non-nematode sequences. The two female-specific ESTs had similarity to vitellogenin-5 and endonuclease III (predicted) from C. elegans. The remaining ESTs had no similarity to any nucleic acid or protein sequences contained in the databases. The isolation and characterisation of sex-specific ESTs from O. dentatum provides a unique opportunity for studying the reproductive biology of parasitic nematodes at the molecular level, with a view toward novel approaches for parasite control.

Concurrent Ascaris suum and Oesophagostomum dentatum infections in pigs

The aim of this study was to examine interactions between Ascaris suum and Oesophagostomum dentatum infections in pigs with regard to population dynamics of the worms such as recovery, location and length; and host reactions such as weight gain, pathological changes in the liver and immune response. Seventy-two helminth-naïve pigs were allocated into four groups. Group A was inoculated twice weekly with 10000 O. dentatum larvae for 8 weeks and subsequently challenge-infected with 1000 A. suum eggs, while Group B was infected with only 1000 A. suum eggs; Group C was inoculated twice weekly with 500 A. suum eggs for 8 weeks and subsequently challenge-infected with 5000 O. dentatum larvae, whereas Group D was given only 5000 O. dentatum larvae. All trickle infections continued until slaughter. Twelve pigs from Group A and B were slaughtered 10 days post challenge infection (p.c.i.) and the remaining 12 pigs from the each of the four groups were slaughtered 28 days p.c.i.. No clinical signs of parasitism were observed. The total worm burdens and the distributions of the challenge infection species were not influenced by previous primary trickle-infections with the heterologous species. Until day 10 p.c.i. the ELISA response between A. suum antigen and sera from the O. dentatum trickle infected pigs (Group A) pigs were significantly higher compared to the uninfected Group B. This was correlated with a significantly higher number of white spots on the liver surface both on Day 10 and 28 p.c.i. in Group A compared to Group B. The mean length of the adult O. dentatum worms was significantly reduced in the A. suum trickle infected group compared to the control group. These results indicate low level of interaction between the two parasite species investigated.

Identification, isolation, and characterization of a species-specific 30-kDa antigen of Oesophagostomum dentatum

In the search for a serology tool for the diagnosis of nonpatent as well as patent infections with Oesophagostomum dentatum in pigs a water-soluble, unglycosilated antigen of about 30 kDa specific for the third-stage larvae of the parasite was purified by ion-exchange chromatography. In Western blots, the antigen was first detected by antibodies at day 7 postinfection. Cross-reactivity with O. quadrispinulatum, Ascaris suum, or Trichuris suis was not detected. It is suggested that this protein is a suitable tool for the species-specific serodiagnosis of O. dentatum infection in pigs.

Development and infectivity of eggs and larvae derived from pigs trickle-infected with Oesophagostomum dentatum at different dose levels

We examined the impact of different Oesophagostomum dentatum dose levels and durations of infection on the development and infectivity of the following generation. Pigs were trickle-infected with 200, 2,000 or 20,000 L3/week over 20 weeks. Egg hatch assays were performed at monthly intervals; however, no consistent differences were found between any of the dose groups in the development of eggs into first-stage larvae. To compare larval infectivity, larvae were derived from faecal cultures set up from the low- and the high-dose groups in the early and the late part of the experiment, and were inoculated into helminth-free pigs (5,000 L3/pig). Worm establishments were significantly higher (P<0.05) in the group of pigs receiving larvae derived early in the experiment from the low-dose group compared with the two groups receiving larvae from high-dose groups, thus indicating an adverse effect of high doses of trickle infection on the later infectivity of L3 larvae derived from excreted eggs.

A study on the establishment of Oesophagostomum dentatum in pigs following percutaneous exposure to third-stage larvae

We examined the possibility of establishment of patent infections after percutaneous exposure of parasite-naive pigs to 10,000 Oesophagostomum dentatum infective larvae (L3). At 5 weeks after percutaneous exposure the pigs were slaughtered and low numbers of adult O. dentatum were recovered from the large intestine. In addition, exsheathed L3 were intravenously injected into pigs, which resulted in the recovery of fourth-stage larvae (L4) from nodules in the lungs as well as of L4 and adult worms from the large intestine. This study demonstrates the ability of porcine nodular worms to establish in the large intestine when pigs have been exposed percutaneously to infective larvae. It is possible that the larvae reach the large intestine by invading blood veins or the lymphatic system at the site of penetration.

Oesophagostomum spp. in pigs: resistance to reinfection

For a study on the occurrence of resistance to reinfection with porcine nodular worm species, pigs were infected twice weekly with 1,000 infective larvae (L3) of Oesophagostomum quadrispinulatum for 8 weeks. All pigs, including noninfected controls, were then treated with fenbendazole. At 10 days after treatment, all pigs received a single challenge inoculation of 5,000 L3 of either O. dentatum or O. quadrispinulatum, respectively. Pigs were slaughtered at 6 weeks after the challenge infection for determination of their worm burdens. The pigs trickle- and challenge-infected with O. quadrispinulatum had significantly lower egg excretion levels (P < 0.01) and worm burdens (P < 0.05) than challenge control pigs, thus indicating some degree of host immunity against the homologous challenge infection. No resistance to reinfection was evident for the heterologous challenge infection. This study elucidates further aspects of the interaction between nodular worm species in the pig.

Effect of time on migration of Oesophagostomum spp. and Hyostrongylus rubidus out of agar-gel

The agar-gel migration technique has previously been described, however, aspects regarding the effect of timing on worm migration needed further scrutiny. In the first experiment, pigs inoculated with Oesophagostomum dentatum were slaughtered simultaneously and their intestines stored at 21-23 degrees C until processed pairwise 2, 4, 6, 8, 12 and 18 h after slaughter. More than 95% of the worms migrated out of the agar if processed within 6 h. In the second experiment, intestines were treated immediately after slaughter and the migratory speed of adult worms or 4th-stage larvae of O. dentatum or O. quadrispinulatum, or adult Hyostrongylus rubidus were studied. For both Oesophagostomum species, more than 90% of the worms were recovered within 1 h. H. rubidus was significantly slower; however, approximately 98% of the worms had migrated out of the agar-gel by 20 h. This information is essential in planning experiments where recovery of live worms is of value.

Genetic diversity in porcine Oesophagostomum dentatum and O. quadrispinulatum and their delineation by isoenzyme analysis

The genetic diversity in eight strains of Oesophagostomum dentatum and O. quadrispinulatum was investigated by the electrophoresis study of ten enzyme systems. The loci Idh-2, Fbp, Sdh, and Pgm were found to be diagnostic between the species examined. Both the proportion of fixed allelic differences (26.3%) and the genetic distance coefficient (D = 0.54) are well above the range for differentiation of valid species. Isoenzyme patterns of susceptible and resistant lines of O. dentatum showed at polymorphic loci a reduced genetic heterogeneity in the latter group. No qualitative difference in terms of the presence/absence of alleles was observed among susceptible and resistant isolates with the enzymes studied. The detection of one possible hybrid indicates that introgression in O. dentatum and O. quadrispinuatum may occur.

Experimental hybridization between Oesophagostomum dentatum and O. quadrispinulatum in pigs

To investigate eventual hybridization between two nodular worm species of pigs, Oesophagostomum dentatum and O. quadrispinulatum, we used either mature, adult worms or 10-day-old fourth-stage larvae (L4) as starting material, employing a nonsurgical transplantation technique. Following the transfer of adult worms the ensuing first generation of larvae gave rise to adult worms that were found by morphological examination to be purely O. dentatum. Therefore, we decided to use the immature L4 as starting material. After the transfer of L4 to recipient pigs, fecal cultures were established and the L3 derived from the O. dentatum male O. quadrispinulatum female cross gave rise to adult but infertile worms, which morphologically had the sexual characters of their parent generation, whereas other characteristics were intermediate between the two species. Attempts to reproduce the hybrid worms or the reciprocal cross were unsuccessful, indicating that hybridization between the two species is a rarely occurring phenomenon.

Experimental Oesophagostomum dentatum infections in the pig: worm populations at regular intervals during trickle infections with three dose levels of larvae

A trickle infection experiment was undertaken to study in detail the population dynamics of Oesophagostomum dentatum in pigs. Three groups of 32 pigs were inoculated via the feed twice weekly with 100 (Group A), 1000 (Group B) or 10,000 (Group C) O. dentatum infective larvae (L3). Five pigs from each group were killed 2, 4, 8, 12, 16, and 20 weeks after the first inoculation (p.i.) to determine their worm burdens. Weekly faecal egg counts were determined. At slaughter, worms were counted, differentiated according to sex and developmental stage, and their length measured. Faecal egg counts ranked with dose rate until week 15, but later were more variable. The proportion of the total number of L3 administered which were recovered at slaughter inversely ranked with dose rate. In group C it decreased over time, whereas in groups A and B there was no consistent pattern. Worm fecundities (epg/female) in groups A and B were higher than in group C. The lengths of the female worms increased over time, whereas the lengths of the male worms remained approximately constant from week 8. The study suggests reduced establishment of incoming larvae and lower fecundity of the female worms at high dose levels.

Making strategy: learning by doing

Companies find it difficult to change strategy for many reasons, but one stands out: strategic thinking is not a core managerial competence at most companies. Executives hone their capabilities by tackling problems over and over again. Changing strategy, however, is not usually a task that they face repeatedly. Once companies have found a strategy that works, they want to use it, not change it. Consequently, most managers do not develop a competence in strategic thinking. This Manager's Tool Kit presents a three-stage method executives can use to conceive and implement a creative and coherent strategy themselves. The first stage is to identify and map the driving forces that the company needs to address. The process of mapping provides strategy-making teams with visual representations of team members' assumptions, those pictures, in turn, enable managers to achieve consensus in determining the driving forces. Once a senior management team has formulated a new strategy, it must align the strategy with the company's resource-allocation process to make implementation possible. Senior management teams can translate their strategy into action by using aggregate project planning. And management teams that link strategy and innovation through that planning process will develop a competence in implementing strategic change. The author guides the reader through the three stages of strategy making by examining the case of a manufacturing company that was losing ground to competitors. After mapping the driving forces, the company's senior managers were able to devise a new strategy that allowed the business to maintain a competitive advantage in its industry.

Dose related mucosal hyperplasia induced by Oesophagostomum dentatum infection in pigs

The present work was undertaken to examine the effects of 3 different population densities of Oesophagostomum dentatum upon the development of worm induced mucosal changes in the colon following single infections. Groups of pigs were infected with single doses of 2000 (low dose), 20,000 (medium dose) or 200,000 (high dose) infective larvae, respectively. A total of 18 infected pigs (6 from each group) were examined for histopathological changes together with 3 helminth-free control pigs. There was a dose related difference in the intensity of colonic lesions; and using morphometry it was observed that the mucosal crypts of pigs in the high dose group were significantly longer than those in the 2 other groups. These differences disappeared by day 25 after infection despite the presence of larvae in the mucosa of the high dose group. This phenomenon may be related to inflammatory reactions in the colon, possibly in connection with the initiation of an immunological response in sites distant from the parasite larvae.

The effect of three distinct sex ratios at two Oesophagostomum dentatum worm population densities

Helminth-free donor pigs were inoculated with infective larvae of Oesophagostomum dentatum. Five weeks later, the donor pigs were killed to recover the adult worms. By nonsurgical rectal transplantation, 6 groups of helminth-free recipient pigs were then given different female-to-male ratios (FMR) of O. dentatum worms (10% females [F], 50% F, 90% F) at either high (300 worms) or low (30 worms) doses. Fecal egg excretions were measured once weekly following transplantation until the pigs were killed 4 wk posttransplantation to assess the worm burdens and their location. There was a strong and significant correlation between numbers of male and female worms located in the different sections of the large intestine, suggesting that the worm sex as well as physiological factors in the pig intestine may govern the location of the worms. There were no significant differences in fecal egg counts or female worm fecundity between any of the groups. However at the low dose level, the female worm fecundity was markedly lower in the L10% F group than in the 2 other groups, thus suggesting for low worm densities an upper threshold for the FMR above which O. dentatum females produce fewer eggs.

Serological assays for the identification of Oesophagostomum dentatum infections in pigs

Oesophagostomum dentatum antigen preparations of third (L3) or fourth (L4) stage larvae were characterised by Western blotting. Panels of sera obtained from pigs infected with O dentatum and Ascaris suum, respectively, reacted with the same bands of L3 antigen. In contrast high specificity against a characteristic band, was observed when L4 extract was employed as antigen. To establish an enzyme-linked immunosorbent assay (ELISA), a panel of homologous and heterologous sera was tested against O dentatum L4 extract. The best combined specificity and sensitivity was obtained when horseradish peroxidase (HRP) goat anti swine IgG conjugate was used rather than HRP rabbit anti swine Ig conjugate. Testing series of sera from pigs infected with single doses of either 2000, 20,000 or 200,000 infective larvae by the ELISA, a significant dose dependency in the antibody response was observed between the low and high dosage groups. This assay may be useful in future studies of the immune-mechanisms against nodular worm infections in pigs.

Rapid PCR-based delineation of the porcine nodular worms, Oesophagostomum dentatum and O. quadrispinulatum

At some stages of development, it is impossible to identify the porcine nodular worms Oesophagostomum dentatum and O. quadrispinulatum to the species level using morphological parameters. A molecular approach utilizing genetic markers in the second internal transcribed spacer (ITS-2) of ribosomal (r) DNA was developed to overcome this limitation. The ITS-2 sequence of each species was determined, and specific oligonucleotide primers were designed to regions of greatest sequence difference between the species. Utilizing these primers, rapid PCR procedures were developed for the specific amplification of DNA of O. dentatum or O. quadrispinulatum, which are now used routinely to monitor the purity of larval cultures and to confirm the identity of larvae derived from the intestine or faeces. The application of specific PCR has major implications for studying the population biology of nodular worms in the pig model.

The effect of concurrent or sequential Oesophagostomum dentatum and O. quadrispinulatum infections on the worm burdens of the two species in pigs

The interaction between the 2 nodular worm species in the pig, Oesophagostomum dentatum (O.d.) and Oesophagostomum quadrispinulatum (O.q.), was studied by comparing the development and distribution of the species following single or mixed infections. The faecal egg excretion levels were assessed at regular intervals from week 3 post-inoculation, and indicated a strong negative impact of the introduction of O.q. on the continued egg excretion of O.d. All pigs were killed 9 weeks after the first inoculations to determine the composition and location of the worm burdens in the large intestine. O.q. was found more anteriorly located in the intestine than O.d., thus confirming previous descriptions. When both species were present, the distribution of O.d. was moved further posteriorly and was more spread out than in single-species infections. There appeared to be no adverse effect of O.d. on the establishment and fecundity of O.q. However, the worm recoveries corroborated the egg excretion observations, namely reduced worm burdens of O.d. if O.q. was introduced, or if O.q. was already present. It is uncertain whether this effect is caused by differences in host reaction against the two species, or whether a more specific competition occurs between the two nodular worm species in pigs.

Use of random amplified polymorphic DNA-polymerase chain reaction for the definition of genetic markers for species and strains of porcine Oesophagostomum

Nodular worms are common parasites of pigs, and research has recently started to focus on the biology of these nematodes. However, the methods for delineation of species at immature developmental stages and for differentiation of various lines of the same species remain limited. For differentiation of porcine Oesophagostomum species and strains by genomic fingerprinting, random amplified polymorphic DNA-polymerase chain reaction was performed on DNA derived from 20 larval batches of anthelmintic-susceptible and resistant strains and isolates of these nematodes and 2 ruminant Oesophagostomum spp. Polymorphic DNA markers could be amplified with 9 of the 33 primers tested. In all, 13 markers were species-specific and 6 markers could differentiate between strains or groups of strains. With a combination of the latter, artificially selected anthelmintic-resistant strains and the susceptible mother strain of O. dentatum could be delineated. When single adult worms were compared, considerable variations between strains of the same species and between individuals from the same strain could be detected. The differentiation of Oesophagostomum strains and species at all parasitic stages on the basis of genetic markers could greatly facilitate studies on the biology of these parasites.

Prepatent periods of different Oesophagostomum spp. isolates in experimentally infected pigs

To define prepatent periods of different Oesophagostomum spp. isolates we carried out two separate experiments, one using two monospecific laboratory isolates and another using laboratory isolates as well as isolates obtained from pig herds having different management systems and with different anthelmintic treatment histories. Pigs were inoculated with 1,000-2,000 infective larvae. Fecal samples were collected daily beginning on days 15 and 16 postinoculation (p.i.). Fecal cultures were set up at different times to yield larvae that could be identified by DNA analyses. All pigs started to excrete eggs on days 18-24 p.i. The mean prepatent period was 20.2 +/- 1.4 days, with no significant difference being observed between species and isolates. Prepatent periods of 17-19 days were found for the monospecific laboratory isolates of O. dentatum and O. quadrispinulatum. These findings conflict with parasitology textbooks; therefore, suggestions as to the possible reasons for the observed short prepatent periods are given.

Non-surgical transplantation of Oesophagostomum dentatum to recipient pigs via rectal intubation

This experimental was designed to evaluate a new transplantation method, which employs a non-invasive rather than a surgical technique for transplanting Oesophagostomum dentatum worms to recipient pigs. Four groups of pigs were used. Group A (four pigs) served as a donor group, and these pigs were each inoculated with 6000 L3 of O. dentatum. Groups B, C, and D (five pigs each) served as helminth naive recipient pigs. On Day 28 post inoculation, the donor pigs were slaughtered, and the worms recovered by an agar-gel technique. Within 3-4 h after slaughter of the donor animals, a mean of 357 worms (male/female = 1.0) were transferred to each of the sedated recipient pigs via a PVC tube inserted approximately 50 cm up into the rectum and colon descendens. The infection was then monitored by weekly faecal egg counts and by killing the recipient pigs at Week 1 (group B), Week 2 (group C), and Week 3 (group D) post transplantation. The majority of the recovered worms were found in the proximal third of the colon, i.e., the normal predilection site of O. dentatum. The mean worm recovery for groups B and D was 85%, whereas from group C it was only 23%. The faecal egg counts were positive throughout the experiment, although low in group C at the time of slaughter 2 weeks post transplantation. The male/female ratios changed from an initial 1.0 to 1.5 group C, whereas there was little or no change in groups B and D. The reason for the deviating results in group C are obscure. This method is less traumatic to animals when compared with surgical transfer techniques, is rapid to perform, and will allow studies on a larger scale.