A prepared mind--Ernest Edward Tyzzer's legacy of research into avian diseases

Ernest Edward Tyzzer (1875-1965) was a physician, specializing at first (1902-1916) in cancer research and then from 1916 as a parasitologist. He was born of English parents in Wakefield, Massachusetts, where he lived all his life. Educated in Wakefield public schools, Brown University (Ph.B., A.M., Hon. Sc.D.), and Harvard University (M.D.), he established during his 40-yr career (1902-1942) an international reputation in oncology, pathology, virology, bacteriology, parasitology, and taxonomic zoology in relation to human and veterinary medicine. His contributions to knowledge of avian diseases were outstanding and wide-ranging. Seminal work included: new descriptions of tumors in chickens; the first record of Cryptosporidium in birds; studies on the biology, morphology, in vitro culture, and epizootiology of the blackhead (histomonosis) parasite and its reclassification under a new genus Histomonas; descriptions of eight new taxa of amebae and flagellates in chickens, turkeys, and ruffed grouse; descriptions of seven new species of Eimeria in chickens, turkeys, pheasants, and quail as well as studies on their biology, immunogenicity, virulence, and epizootiology; a description of the trematode Collyriclum in English sparrows; the first record of mycosis in ruffed grouse; the recognition of birds as a source of equine encephalomyelitis infections of humans; the first American record of infectious sinusitis in turkeys and discovery of a curative treatment; and studies of Newcastle disease and avian influenza during the war research program of the 1940s. Application of Tyzzer's histomonosis research to farm practice saved the Massachusetts turkey industry from extinction in the 1920s and significantly influenced the recovery of turkey farming nationally.

Systolic blood pressure and adiposity: examination by race and gender in a nationally representative sample of young adults

BACKGROUND

Adiposity, or more specifically, underlying body fat distribution, has been associated with systolic blood pressure (SBP), and it has been suggested that these associations vary between whites and blacks, as well as by gender.

METHODS

Here, we use data from the National Longitudinal Study of Adolescent Health (Add Health), a US study of over 15,000 participants (median age 29.0 years), to characterize the associations between measures of body fat distribution-waist circumference (WC) and WC adjusted for body mass index (BMI) (WC(-bmi))-with SBP within white and black race and gender subgroups.

RESULTS

Our findings suggest that, at lower levels of WC(-bmi), white women have significantly higher SBP as compared to black women, whereas black men have higher SBP than white men. Black women with WC(-bmi) >90 cm have higher SBP compared to white women with similar WC(-bmi), whereas among black and white men the associations are essentially similar across the full range of WC(-bmi).

CONCLUSIONS

The present results suggest that associations among anthropometric measures of adiposity and blood pressure are nonlinear, and importantly, vary for whites and blacks by gender. In black women, SBP increased more as WC increased from low- to mid-range levels, whereas it was only at higher WC levels that black men exhibited higher SBP than white men.

Pathogenesis of Eimeria praecox in chickens: virulence of field strains compared with laboratory strains of E. praecox and Eimeria acervulina

The pathogenesis in chickens of the apicomplexan Eimeria praecox was compared with that of Eimeria acervulina, using intestinal lesions, mucosal integrity, body weight gain (BWG) and the feed conversion ratio (FCR) as criteria. Characteristics of each species were described by combinations of polymerase chain reaction assays and classic parasitological signs. There were considerable overlaps in lengths, breadths, shape indices and volumes of the oocysts of each species. Both species caused statistically significant reductions in BWG at the lowest inocula tested (500,000 sporulated oocysts per bird of E. praecox and 250,000 of E. acervulina). E. praecox was observed for the first time to cause actual body weight loss and marked increases in FCR, as did E. acervulina. E. acervulina caused gross, white pathognomonic lesions, but E. praecox caused micro-lesions, visible in fresh tissue only with a dissecting microscope. Occasionally, lesions of the Houghton strain of E. acervulina were observed to be rounded, rather than typically "ladder-like". Both species caused villous erosion and atrophy. No mortality occurred in birds receiving up to 1 million sporulated oocysts of either species. Using BWG and FCR as criteria, the virulence of recent field strains of E. praecox from Wales (Tynygongl) and the USA (Raleigh) was compared with English laboratory strains of E. praecox (Houghton) and E. acervulina (Houghton). E. praecox (Tynygongl) was markedly more virulent than E. acervulina (Houghton), which was more virulent than E. praecox (Raleigh) and E. praecox (Houghton).

The effects of zinc deficiency on pancreatic carboxypeptidase activity and protein digestion and absorption in the rat

1. Proteolytic enzyme activities were examined in the pancreas of zinc-deficient and control rats. 2. No change was detected in trypsin-plus-chymotrypsin activity. 3. Carboxypeptidase activity was appreciably lowered in zinc deficiency and returned rapidly to normal on zinc therapy. 4. In experiments in which U-(14)C-labelled Chlorella protein was fed no evidence was obtained which suggested that the reduction in carboxypeptidase activity had limited the rate of protein digestion or absorption. 5. The specific activity of pancreatic protein synthesized during these experiments was appreciably lower in zinc-deficient than in control rats. 6. A higher proportion of the total activity present, in each organ examined, was in the non-protein fraction in zinc-deficient rats.

Anticoccidial vaccination: The absence or reduction of numbers of endogenous parasites from grosslesions in immune chickens after virulent coccidial challenge

Male and female floor-reared chickens were immunized with a live, attenuated anticoccidial vaccine (Paracox) and then, 28 days after vaccination, were challenged with virulent strains of Eimeria acervulina, Eimeria brunetti, Eimeria maxima, Eimeria necatrix or Eimeria tenella. The relationship between the post-challenge growth rate and specific gross lesion grades, matched in individual birds, was examined. The numbers of endogenous parasites associated with graded lesions of each species were compared with those in challenged naive control birds. The vaccinated chickens were clinically immune judged by weight gains, but the naive controls reared under the same conditions were unprotected. The mean weight gains of vaccinated, immune birds had lower coefficients of variation than those of unvaccinated, unprotected birds challenged with the same species. Whichever Eimeria species the birds were challenged with, a proportion (5 to 75%) of the challenged, vaccinated, immune birds exhibited some coccidial lesions, mostly graded 1 or 2 (on a scale of 0 to 4); whereas all unvaccinated, unprotected birds had severe coccidial lesions, mostly graded 4. Innumerable endogenous parasites were associated with all lesions seen after challenging unvaccinated, naive birds, but 68% of the gross lesions in challenged, vaccinated, immune birds had no associated parasites, and the remaining 32% had very few. It is concluded that the use of lesion grades alone to assess an anticoccidial vaccine may under-rate its efficacy, and that the occasional presence of gross lesions in commercially vaccinated chickens does not indicate vaccine failure unless performance is also adversely affected. Although in a naive bird gross lesions usually indicate disease, the presence of any gross lesions in a bird judged by performance criteria to be immune may be interpreted as the host's successful repulsion of a parasite challenge.

Risk factors for epistaxis on British racecourses: evidence for locomotory impact-induced trauma contributing to the aetiology of exercise-induced pulmonary haemorrhage

REASONS FOR PERFORMING STUDY

The proposed biological mechanisms for exercise-induced pulmonary haemorrhage (EIPH) are many and varied. Better knowledge of risk factors should lead to achievable measures to reduce the incidence.

OBJECTIVES

To identify risk factors associated with epistaxis following racing in UK Thoroughbreds, to gain possible insights into the pathogenesis of the condition and to investigate the association between epistaxis and race finishing position.

METHODS

The association of epistaxis occurring on UK racecourses between 1996 and 1998 with a wide range of race-, horse- and start-level variables was examined in multivariable mixed effect logistic regression analyses. Four multivariable analyses were conducted, one for all race types considered collectively and one each for flat, hurdle and steeplechase race types considered separately.

RESULTS

Risk of epistaxis was significantly increased for hurdle and steeplechase race types compared to both flat and National Hunt flat races. In 3 of the 4 final models, there was a significant biological trend for increasing risk of epistaxis with increasing ground hardness ('going') and accumulated years spent racing. However, in flat races epistaxis was such a rare outcome (0.33 cases per 1000 starts) that this subset analysis had insufficient power to measure the detectable effect of 'going' as statistically significant. Horses with epistaxis were significantly more likely to have a poorer finishing position than those without blood at the nostrils.

CONCLUSIONS

Findings were consistent with the theory that locomotory impact-induced trauma contributes to exercise-induced epistaxis. Further validation of this hypothesis through application of similar methods to endoscopically visible EIPH and through biomechanical studies is warranted.

POTENTIAL RELEVANCE

Knowledge of significant risk factors should allow formulation of practical measures, such as track watering, to reduce the risks of EIPH and epistaxis in racehorses.

Positive affect is associated with cardiovascular reactivity, norepinephrine level, and morning rise in salivary cortisol

Positive affect was examined as a predictor of (1) cardiovascular reactivity during a sadness and an anger recall task and recovery following the protocol, (2) epinephrine (EPI) and norepinephrine (NOREPI) reactivity and level during the recall protocol, and (3) the diurnal pattern of salivary cortisol. Sample was 328 individuals. Negative affect, age, race, sex, smoking status, income, and BMI were adjusted. During sadness recall, positive affect was inversely related to systolic blood pressure (p=.007) and diastolic blood pressure (p=.049) reactivity, and unrelated to heart rate (p=.226). Positive affect was unrelated to reactivity during anger recall (ps>.19), and was unrelated to recovery at the end of the recall protocol. Positive affect was inversely related to the mean level of NOREPI (p=.046), and unrelated to EPI (p=.149). Positive affect was inversely related to the increase in cortisol 30 min post awakening (p=.042), and unrelated to the evening decline in cortisol levels (p=.174). Positive emotions may be relevant to good health.

A survey of Eimeria species in commercially-reared chickens in France during 1994

In a survey of chicken coccidia in France during 1994, samples of litter were collected from 41 farms. On 31 of these farms, eimerian oocysts were abundant enough to allow monitoring of their numbers in the litter. Peak total oocyst counts on these farms ranged from 16,200 to 1,254,000/g of litter, but no coccidiosis was observed. The chickens reared without anticoccidial agents in their food (poulets biologiques) produced higher and earlier peak oocyst counts in litter than the chickens given medicated food (poulets labels). The oocysts in litter samples from 22 farms (13 poulet biologique, five poulet label, two standard broiler, one breeder and one layer) of the original 41 were identified. Six of the seven eimerian species known to parasitize chickens were found, using combinations of five methods (oocyst morphology, intestinal lesions, enzyme electrophoresis, growth in embryonating eggs and prepatent time). Multispecific infections predominated (95% of 22 farms), up to six species occurring together. Of farms where oocysts were detected, the percentages with each species were: Eimeria acervulina (100%), E. mitis (82%), E. tenella (77%), E. maxima (73%), E. praecox (45%) and E. brunetti (27%). These appear to be the first definite records of E. mitis and E. praecox for France. Although E. necatrix was not found in this survey, it had recently been detected by other workers in France, so that all seven chicken Eimeria species were known to be contemporaneous.

Counting coccidial oocysts in chicken faeces: A comparative study of a standard McMaster technique and a new rapid method

For the assessment of coccidial oocyst production by chickens, some modified form of the McMaster counting method is commonly used. The objective of this study was to evaluate a standard method and to compare it to a new, faster method, in which all the preparative stages before counting are carried out in the same container into which the original faecal sample was collected. A stock suspension containing purified oocysts of all seven valid Eimeria species that parasitize chickens was prepared, from which seven concentrations of oocyst suspensions were made. Since the faecal material in a sample influences the ability of oocysts to float up in a McMaster chamber, the new method was tested to establish the optimal amount of faeces in the original sample. Control oocyst suspensions containing no faeces were also tested, and three series of counts using the new method were compared with the standard McMaster method. The results were statistically analysed by agreement analysis. Repeatability and between-operator variation of both methods were also tested by agreement analysis. Counting by the standard McMaster method underestimated the true number of oocysts. The new method gave counts in agreement with the true number of oocysts if using 1 g of faeces per sample. With 2 g of faeces, counts were obtained that agreed with counts by the standard McMaster method. Both methods showed agreement between repeated measurements. The new method used on a sample containing 2 g of faeces provides a convenient alternative to the standard modified McMaster method. A 1-g faecal sample increases agreement with the true numbers of oocysts. Processing of a sample with the new method is about nine times faster than with the standard method.

Tracing the emergence of drug-resistance in coccidia (Eimeria spp.) of commercial broiler flocks medicated with decoquinate for the first time in the United Kingdom

Decoquinate is a quinolone coccidiostat introduced during 1967 as an in-feed prophylactic for broiler chickens. Despite early drug-resistance problems and its age, the drug is still used commercially worldwide. Decoquinate here serves as a valuable model in a field study that addresses the dynamics and economic impact of the development of coccidial resistance to potent synthetic anticoccidial drugs. The results of this unique, hitherto unpublished, study on the initial emergence of resistance of avian coccidia (Eimeria spp.) to a new drug in the field may be of strategic value in the continued use of decoquinate or the introduction of new drugs. The commercial performance of the first 3-5 crops of broilers to be medicated with decoquinate on each of six farms was monitored during 14 months in 1968-1969, supplemented by assessments of the species, population dynamics and decoquinate-resistance of coccidia isolated from each farm. During the rearing of each flock in a single shed on each farm, oocysts were counted in fresh faecal samples collected on three occasions, and the species were identified by their morphology if possible, supported if necessary by the biological characteristics of infections in chickens. E. acervulina was the most common species, followed by E. mitis, E. maxima, E. tenella and E. praecox. E. brunetti occurred rarely, and E. necatrix was not found. Decoquinate-resistance was evident in several species during the rearing of the first decoquinate-medicated crop on each farm, although clinical coccidiosis did not occur. It was concluded that inherently resistant mutants of E. acervulina, E. brunetti, E. maxima, E. tenella, and probably also E. mitis and E. praecox, were selected from field populations by 6 weeks during their first exposure to decoquinate. During up to four more subsequent crops, cycling of resistant parasites stimulated host immunity, which had no obvious adverse impact on commercial performance. There was no apparent seasonal effect. A hypothesis is proposed to explain the sudden and rapid emergence of quinolone-resistance in the coccidia, and why bird health was not thereby compromised in these circumstances.

Relative virulences of a drug-resistant and a drug-sensitive strain of Eimeria acervulina, a coccidium of chickens

The virulence of a field strain of the chicken coccidian parasite Eimeria acervulina (Boreham I), dually resistant to the chemically unrelated anticoccidial agents decoquinate and clopidol, was compared with that of a drug-sensitive laboratory strain (Ongar) of the same species. Following a single heavy infection (prevented from recycling), both strains exhibited pathogenic effects typical of their species, viz., pathognomonic lesions, adverse effects on body weight gain and feed conversion ratio (FCR), but no mortality. One week after infection, chicks infected with either strain had a statistically significantly worse weight gain than the uninfected control; the Boreham I strain produced more oocysts, and caused slightly more severe duodenal lesions and poorer FCRs than the Ongar strain (all those effects being non-significant). After 3 weeks, there were no significant differences between any cumulative effects of either strain, nor any differences from the uninfected control. However, from 2 to 3 weeks after infection, chicks infected with either strain had a greater feed consumption and growth rate than uninfected chicks. When chicks reared on solid floors were given lighter infections of either strain, which were allowed subsequently to recycle naturally, there were no consistent reductions in weight gains, but feed consumption was higher than that of uninfected chicks. Whatever, the mode of infection, there were no significant differences between the weights of infected and uninfected chicks after 3 weeks, but the FCR of infected chicks was usually poorer than that of uninfected chicks. The difference between the virulences of the Boreham I and Ongar strains was not greater than that between various drug-resistant strains or between various sensitive strains of several Eimeria species recorded in the literature. It is therefore concluded that there was no difference between the virulences of the two strains of E. acervulina that could be attributed to the drug-resistance of one of them.

High-power Yb-doped multicore ribbon fiber laser

A highly elongated double-clad ribbon fiber that comprises a pure-silica inner cladding with transverse dimensions of approximately 1.4 mm by 0.23 mm with a linear array of ten ytterbium-doped cores has been fabricated and operated in a simple laser configuration pumped by two diode stacks. The fiber laser yielded 320 W of output power at a center wavelength of 1045 nm in a combined beam with beam propagation factors of approximately 2 (perpendicular to the array) and approximately 150 (parallel to the array) for 576 W of launched pump power. The slope efficiency with respect to absorbed pump power was 62%. The prospects for further power scaling and improved beam quality and efficiency are discussed.

Guidelines for evaluating the efficacy and safety of live anticoccidial vaccines, and obtaining approval for their use in chickens and turkeys

These guidelines are intended to aid those engaged in poultry research in the design, implementation and interpretation of laboratory, floor-pen and field studies for the assessment of the efficacy and safety of live anticoccidial vaccines for immunization of chickens and turkeys against Eimeria species. In addition to efficacy and safety requirements, manufacture, quality control and licensing considerations are discussed. The guidelines do not address subunit vaccines comprising non-viable material, but many of the principles described will be relevant to such vaccines if they are developed in the future. Guidelines are available in some countries for avian vaccines of bacterial or viral origin but specific standards for anticoccidial vaccines in poultry have not, as far as we know, been produced. Information is provided on general requirements of registration authorities (based upon regulations applicable in the European Union and the USA) for obtaining marketing authorizations for vaccines. These guidelines may assist poultry specialists in providing specific information for administrators involved in the decision-making process leading to registration of new vaccines, and are intended to facilitate the worldwide adoption of consistent, standard procedures.

The efficacy of a mixture of trimethoprim and sulphaquinoxaline against Plasmodium gallinaceum malaria in the domesticated fowl Gallus gallus

The apicomplexan parasite Plasmodium gallinaceum has not been much studied from the veterinary standpoint. Although it causes malaria in domesticated chickens, no effective drugs appear to be commercially available. A mixture of trimethoprim and sulphaquinoxaline (TMP/SQX, ratio 1:3), with a wide spectrum of activity against bacteria and coccidia, is here shown to be also efficacious against blood-induced P. gallinaceum malaria when administered therapeutically in the feed of chickens for 5-day periods, beginning on the day before infection, or on the day of infection, or up to four days after infection. Chickens were protected against mortality and reduction of weight gain. Three other criteria of efficacy, which showed good correlation with each other and also with the two commercial performance criteria, were the production of green diarrhoea (due to biliverdin), parasitaemia and reduced haematocrit values. When TMP/SQX treatments were initiated sooner than five days after infection, parasites were almost entirely eliminated from the blood, whereas treatments initiated later than four days after infection failed to protect birds against clinical disease. Birds protected by TMP/SQX against primary infection with P. gallinaceum were immune to clinical malaria when exposed to a severe blood-induced challenge of P. gallinaceum 28 days later.

Intercurrent coccidiosis and necrotic enteritis of chickens: rational, integrated disease management by maintenance of gut integrity

Coccidiosis and necrotic enteritis (NE) are globally common, sometimes intercurrent, diseases of poultry. The risk of NE, due to the Gram-positive bacterium Clostridium perfringens, has increased in recent years because of the voluntary or legally required withdrawal of the use of certain in-feed antibiotic growth promoters with anticlostridial activity. In-feed ionophorous anticoccidial drugs incidentally also possess anticlostridial activity. Such ionophores, although not banned, are usually precluded when live anticoccidial vaccines are used, potentially increasing yet further the risk of NE. This review provides information for the design of rational, integrated management strategies for the prevention and control of coccidiosis and NE in chickens by maintaining gut integrity. Because of differences in local availability of feed ingredients and national legislations regarding antibiotic growth promoters and anticoccidial vaccine licensing, no universal strategy is applicable. The diseases and their interactions are described under the headings of forms of disease, diagnosis, sources of infection, pathophysiological effects, predisposing factors, and control methods. Elements of gut integrity, which influences host predisposition and clinical responses to disease, include physical development, immune competence, gut enzyme activity, mucin production, gut flora and epithelial damage. Experimental studies of coccidiosis and NE are compared, and where possible reconciled, with field observations. Gaps in knowledge and necessary further experiments are identified. Insights are provided regarding interactions between coccidiosis, NE, and the use of live anticoccidial vaccines. Recent changes in NE prevalence in commercial flocks, and their possible causes, are discussed. The necessarily wide range of topics reviewed emphasizes the enormous complexity of this disease combination, and indicates the importance of a multidisciplinary approach in order to reduce its harmful impact on the world's poultry industry.

Avian malaria: clinical and chemical pathology ofPlasmodium gallinaceumin the domesticated fowlGallus gallus

Data on the effects of Plasmodium gallinaceum on domesticated fowl are sparse, justifying a full investigation of its pathology. Clinical signs following blood-induced infections with the Wellcome line of strain 8A included depression, fever, anorexia, reduced weight gain, poor feed conversion, anaemia, green faeces and often death. After administration of 10(6) erythrocytic parasites, mortality 5 to 10 days after infection was 10% to 93% in chickens 7 to 84 days old. The older the birds, the lower the mortality and the longer the time to death. Onset of detectable parasitaemia occurred mostly during the second day after infection (59% of birds). Peak parasitaemia (approximately 70%) occurred on the sixth day in 85% of surviving birds. The patent period was usually 7 to 19 days. Abnormally low haematocrit values of < or =24% and high colonic temperatures of > or =42 degrees C were recorded. A febrile response is demonstrated conclusively here in P. gallinaceum malaria for the first time. Weight gain of malarious birds was reduced by approximately 18% to 51%, and feed conversion efficiency was often reduced by approximately 12% to 41%. Growth reduction was due entirely to anorexia. Liver weight relative to body weight (normally approximately 2% to 3%) increased to approximately 4.5% by 8 days, and relative spleen weight (normally approximately 0.2%) increased to 1.6% by 12 days. Specific gravities of livers and spleens in healthy and infected birds were approximately 1.09. Gall bladder volume in malarious birds 8 days after infection was approximately four times that of normal birds. Statistically significant changes occurred in the proportions of plasma proteins in malarious birds 8 days after infection; albumin and alpha2-globulin were reduced, while gamma1-globulin and gamma2-globulin were increased. Those changes coincided with significant increases in concentrations of plasma total protein and the enzymes aspartate aminotransferase, glutamate dehydrogenase and gamma-glutamyltransferase, and a decrease in creatinine. Green (biliverdin) colouration of the faeces was a consistent sign of malaria. Birds acquired non-sterile immunity after a single primary infection. The quantitative data presented facilitate selection of the most useful criteria for field diagnosis, estimation of potential economic losses, and assessment of potential avian antimalarial drugs.

Psychosoziale Faktoren bei koronarer Herzkrankheit - wissenschaftliche Evidenz und Empfehlungen für die klinische Praxis

Psychosocial risk factors like low socio-economic status, lack of social support and social isolation, chronic work or family stress, as well as negative emotions, e. g. depression and hostility, contribute significantly to the development and adverse outcome of coronary heart disease (CHD). Negative effects of psychosocial risk factors are conveyed via behavioural pathways including unhealthy lifestyle, e. g. food choice, smoking, sedentary life, inadequate utilisation of medical resources, and psychobiological mechanisms like disturbed autonomic and hormonal regulation: all these factors contribute to metabolic dysfunction and inflammatory and haemostatic processes, which are directly involved in the pathogenesis of CHD. Interventions to improve pychosocial factors are available and have demonstrated positive effects on risk factors and - at least in part - on CHD morbidity and mortality. The prevention of CHD should therefore include screening for psychosocial risk factors and adequate interventions. Recommedations for the screening of risk factors, behavioural change and further management of psychosocial risk factors in clinical practice are pointed out.

Efficient single-axial-mode operation of a Ho:YAG ring laser pumped by a Tm-doped silica fiber laser

Efficient single-frequency operation of a Ho:YAG ring laser at room temperature with a traveling-wave TeO2 acousto-optic modulator to enforce unidirectional operation is reported. By use of a 2-at. % Ho3+-doped 10-mm-long Ho:YAG rod, end pumped by a cladding-pumped tunable Tm-doped silica fiber operating at 1.9 microm, the Ho:YAG ring laser yielded 3.7 W of single-frequency output at 2.1 microm in a diffraction-limited TEM00 beam with M2 < 1.1 for an incident pump power of 8.8 W. The rf power required for unidirectional operation was 0.3 W and corresponded to an increase in cavity loss for the lasing direction (due to diffraction) of only 0.5%. The prospects for further improvement in efficiency are discussed.

Single-mode direct-ultraviolet-written channel waveguide laser in neodymium-doped silica on silicon

A waveguide laser with a neodymium-doped silica core is fabricated on a silicon substrate by a combination of flame hydrolysis deposition, solution doping, and direct UV writing. The neodymium-ion concentration is estimated to be approximately 8000 parts in 10(5). The propagation loss around 1.05 microns is < 0.8 dB/cm. Lasing in the range 1048-1056 nm and 1356 +/- 1 nm is observed. A slope efficiency of 33% for a high-reflectivity output coupler and a threshold of 4 mW of absorbed power for a 25% output coupler are measured for the 4F3/2-->4I11/2 transition.

World Association for the Advancement of Veterinary Parasitology (WAAVP) guidelines for evaluating the efficacy of anticoccidial drugs in chickens and turkeys

These guidelines have been written to aid in the design, implementation and interpretation of studies for the assessment of drug efficacy against Eimeria species in chickens and turkeys. The information provided deals with many aspects of how to conduct controlled studies in battery cages (dose determination), floor pens (dose confirmation), and commercial facilities (field effectiveness studies), the selection of birds, housing, feeding, preparation of medicated rations, record keeping, diagnostic techniques, and methods for the preparation, maintenance and use of parasites. These guidelines are also intended to assist investigators in conducting specific studies, provide specific information for registration authorities involved in the decision-making process, assist in the approval and registration of new anticoccidial drugs, and facilitate the world-wide adoption of standard procedures.

A new method for the experimental production of necrotic enteritis and its use for studies on the relationships between necrotic enteritis, coccidiosis and anticoccidial vaccination of chickens

A new method for the experimental production of necrotic enteritis in chickens is described. The main features are the use of a diet high in wheat and fish meal content; oral administration of a non-lethal inoculum of the coccidium Eimeria maxima followed 6 days later by the bacterium Clostridium perfringens type A per cloaca, so that the bacterial inoculum is deposited at the time and place when and where the intestinal coccidial lesions are maximal; grading of coccidial and clostridial lesions in individual birds sampled during the 14 days following the coccidial infection. The new method was used to examine the relationship between clostridial and coccidial infections. Frank coccidiosis, caused by virulent E. maxima, exacerbated the lesions of necrotic enteritis and other clinical effects due to a subsequent challenge with virulent C. perfringens type A. Immunization with a live, pentavalent, attenuated anticoccidial vaccine (Paracox-5) protected against a severe challenge with heterologous E. maxima. Furthermore, vaccination with Paracox-5, by virtue of its protection against clinical coccidiosis due to the E. maxima challenge, indirectly protected birds against a subsequent challenge with virulent C. perfringens. The results are reconciled with previous field observations on concomitant coccidiosis and necrotic enteritis in chicken flocks.

Biomechanics, diagnosis, and treatment outcome in inflammatory myopathy presenting as oropharyngeal dysphagia

AIMS

In patients with inflammatory myopathy and dysphagia, our aims were to determine: (1) the diagnostic utility of clinical and laboratory indicators; (2) the biomechanical properties of the pharyngo-oesophageal segment; (3) the usefulness of pharyngeal videomanometry in distinguishing neuropathic from myopathic dysphagia; and (4) clinical outcome.

METHODS

Clinical, laboratory, and videomanometric assessment was performed in 13 patients with myositis and dysphagia, in 17 disease controls with dysphagia (due to proven CNS disease), and in 22 healthy age matched controls. The diagnostic accuracy of creatine kinase (CPK), erythrocyte sedimentation rate, antinuclear antibody, and electromyography (EMG) were compared with the gold standard muscle biopsy. The biomechanical properties of the pharyngo-oesophageal segment were assessed by videomanometry.

RESULTS

Mean time from dysphagia onset to the diagnosis of myositis was 55 months (range 1-180). One third had no extrapharyngeal muscle weakness; 25% had normal CPK, and EMG was unhelpful in 28%. Compared with neurogenic controls, myositis patients had more prevalent cricopharyngeal restrictive disorders (69% v 14%; p=0.0003), reduced upper oesophageal sphincter (UOS) opening (p=0.01), and elevated hypopharyngeal intrabolus pressures (p=0.001). Videomanometric features favouring a myopathic over a neuropathic aetiology were: preserved pharyngeal swallow response, complete UOS relaxation, and normal swallow coordination. The 12 month mortality was 31%.

CONCLUSIONS

The notable lack of supportive clinical signs and significant false negative rates for laboratory tests contribute to the marked delay in diagnosis. The myopathic process is strongly associated with restricted sphincter opening suggesting that cricopharyngeal disruption is a useful adjunct to immunosuppressive therapy. The condition has a poor prognosis.

Fifty years of anticoccidial vaccines for poultry (1952-2002)

Although earlier investigators experimented with anticoccidial vaccines, the world's first commercially successful product was developed by Prof S. A. Edgar of Auburn University, Auburn, AL. This product contained live, nonattenuated Eimeria tenella oocysts and was first marketed by Dorn and Mitchell, Inc., in 1952. Under the trade names of DM Cecal Coccidiosis Vaccine, Coxine, NObiCOX, and CocciVac, it went through several formulations containing various Eimeria species that parasitize chickens, and a further product containing turkey Eimeria species was also developed. After many product and company changes, one turkey and two chicken formulations of CocciVac are still marketed worldwide by Schering-Plough Animal Health, Inc. Chicken and turkey formulations of Immucox, a similar type of vaccine, were developed by Dr. E.-H. Lee and first marketed in 1985 in Canada by Vetech Laboratories, Inc. In 1974, Dr. T. K. Jeffers of Hess and Clark, Inc., Ashland, OH, published his discovery of precocious lines of coccidia, which facilitated the development of the first attenuated anticoccidial vaccine. For commercial reasons, Jeffers was unable to do this himself, but this first attenuated vaccine was designed by Dr. M. W. Shirley and colleagues at the Houghton Poultry Research Station (HPRS) in the United Kingdom. The vaccine was commercially developed under license in the United Kingdom by Glaxo Animal Health Ltd. and then Pitman-Moore, Inc., and launched in The Netherlands during 1989 under the trade name Paracox. After further changes in company ownership, two formulations for chickens are now marketed worldwide by Schering-Plough Animal Health, Inc. Attenuation of coccidia by embryo adaptation was reported in 1972 in the United Kingdom by Dr. P. L. Long, who originally worked at the HPRS and later became a professor at the University of Georgia, Athens, GA. An embryo-adapted line of E. tenella was included with precocious lines of other species in a series of three attenuated vaccines for chickens under the trade name Livacox, developed by Dr. P. Bedrník and launched in the Czech Republic in 1992 by Biopharm. The formulations of all other commercially available live anticoccidial vaccines for poultry are currently based upon the scientific principles established for the CocciVac, Paracox or Livacox vaccines.

Anticoccidial vaccines for broiler chickens: pathways to success

The use of live vaccines, either attenuated or non-attenuated, for the control of coccidiosis due to Eimeria infections in broiler breeder or layer chickens is well established. Use in broilers, however, has been slow to gain acceptance. This has been partly for economic reasons, but also because of perceived adverse effects on early chick growth, particularly with non-attenuated vaccines, and concerns about timely onset of protective immunity in such short-lived birds. This review describes advances in understanding of epidemiological factors and recent improvements of administration methods that have helped to allay these fears and to make the use of anticoccidial vaccines in broilers technically achievable. Topics discussed include: (1) types of commercially available vaccine, (2) vaccines in development, (3) vaccination methods and equipment, (4) basis of vaccine efficacy and immunogenic variation of parasites, (5) key factors in the survival, sporulation and dissemination of vaccinal oocysts, (6) descriptions and significance of patterns of litter oocyst accumulation and occurrence of intestinal lesions in vaccinated flocks, (7) rotation of anticoccidial vaccination and chemotherapy to restore drug sensitivity to resistant wild-type coccidia, (8) combinations of anticoccidial vaccination and chemotherapy, (9) interactions between coccidiosis and clostridiosis in broilers and compatibilities of potential control methods, (10) published performance data for live anticoccidial vaccines in broilers, (11) possible further developments of live vaccines.

Comparison of an attenuated anticoccidial vaccine and an anticoccidial drug programme in commercial broiler chickens in Italy

A live attenuated anticoccidial vaccine (Paracox) was compared with a nicarbazin-monensin anticoccidial drug shuttle programme in three crops of Italian broilers, comprising a total of 290,405 chickens. All birds received the antibiotic growth promoter avilamycin. No coccidiosis was evident during the trials, but the occurrence of oocysts in the litter demonstrated that a natural challenge was present. Vaccinated birds consistently performed at least as well as those treated with the anticoccidial drug shuttle. The final mean weights of vaccinated birds were significantly greater (P < 0.001) than those of birds treated with anticoccidial drugs, both for females at 36/37 days and males at 56 days. Feed conversion ratios, total mortality including culls, the proportion of rejects at the processing plant, and the moisture content of the litter were not significantly different between the two control methods. Growth curves showed that there was no post-vaccinal growth check in the vaccinated birds and no intolerance of the anticoccidial drug treatment. There was no overall seasonal effect, regardless of treatment, on the performance of the three crops reared from November 1997 to July 1998. These findings suggest that the use of this vaccine is likely to enable the replacement of anticoccidial drug shuttle programmes in broilers reared under conditions similar to those used in these Italian flocks.

Sustainable coccidiosis control in poultry production: the role of live vaccines

The development of new methods of administering coccidiosis vaccines has facilitated their use in the hatchery and thereby improved prospects for the economic vaccination of broilers. The acquisition of protective immunity to Eimeria species is boosted by further exposure to infection after vaccination. Factors that affect the reproductive efficiency of non-attenuated and attenuated vaccines are considered and the key role that oocyst production plays in establishing and maintaining uniform immunity in a flock of chickens is discussed. In addition to immunisation, a possible advantage to the application of certain vaccines is that their use could repopulate poultry houses with drug-sensitive organisms. Theoretical rotation programmes in which the use of drugs is alternated with that of vaccines are described. Variability of the cross-protective immune response between strains of the same species should be considered during vaccine development and subsequent use. The significance of less common species of Eimeria, not included in all vaccines, also needs to be assessed. An important consideration is the occurrence of pathogens other than Eimeria (such as the bacterium Clostridium) in flocks given coccidiosis vaccines and the methods by which they might be controlled. More research is required into the relationship between bacterial and viral infections of poultry and coccidiosis vaccination. Vaccines need to be developed that are simple to apply and cost effective for use in areas of the world where small-scale poultry production is commonplace. In the near future it is likely that more live vaccines based upon oocysts derived from attenuated strains of Eimeria will be developed but in the longer term vaccines will be based on the selective presentation to the host of specific molecules that can induce protective immunity. This achievement will require significant investment from the private and public sectors, and, if successful, will facilitate the sustainable control of coccidiosis in poultry production.

Space-time pressure structure of pharyngo-esophageal segment during swallowing

We applied high-resolution manometry with spatiotemporal data interpolation and simultaneous videofluoroscopy to normal pharyngeal swallows to correlate specific features in the space-time intraluminal pressure structure with physiological events and normal deglutitive transsphincteric bolus flow to define normal biomechanical properties of the pharyngo-esophageal (PE) segment. Pressures were recorded by microperfused catheter, and the two-dimensional space-time data sets were plotted as isocontours. On these were superimposed bolus trajectories, anatomic segment movements, and hyo-laryngeal trajectories from concurrent videofluoroscopy. Correlation of the highly reproducible space-time-pressure structure with radiographic images confirmed that primary deglutitive PE segment functions (pressure profile, laryngeal elevation, axial sphincter motion, timing of relaxation, contraction) are accurately discernible from single isocontour pressure visualization. Pressure during bolus flow was highly dependent on axial location within PE segment and time instant. The intrabolus pressure domain, corresponding to the space-time region between bolus head and tail trajectories, demonstrated significant bolus volume dependence. High-resolution manometry accurately, comprehensively, and highly reproducibly depicts the PE segment space-time-pressure structure and specific physiological events related to upper esophageal sphincter opening and transsphincteric flow during normal swallowing. Intrabolus pressure variations are highly dependent on position within the PE segment and time.

Improved functional ability in patients with rheumatoid arthritis--longterm treatment with leflunomide versus sulfasalazine. European Leflunomide Study Group

OBJECTIVE

We previously reported that the new disease modifying antirheumatic drug leflunomide resulted in significant improvement in functional ability compared with placebo and sulfasalazine in a 6 month double blind, randomized, Phase III trial in rheumatoid arthritis (RA). The current study compared functional disability in cohorts of patients with RA from the initial study who volunteered to continue treatment with leflunomide or sulfasalazine.

METHODS

The Health Assessment Questionnaire (HAQ) was used to assess functional ability in patients completing 6 months of therapy who chose to continue in double blinded 12 and 24 month extensions. Patients on active regimens continued taking leflunomide 20 mg/day or sulfasalazine 2 g/day; those taking placebo were switched at Month 6 to sulfasalazine.

RESULTS

Leflunomide significantly improved patients' functional ability compared to placebo (p < or = 0.0001) and sulfasalazine (p < or = 0.01) at 6 months. These changes were seen as early as Month 1, and continued improvements were seen in 12 and 24 month cohorts. Mean HAQ scores were significantly improved with leflunomide compared with sulfasalazine at 24 months (-0.65 vs -0.36; p = 0.0149); corresponding changes in HAQ Disability Index (DI) were -0.73 vs -0.56 and were not statistically different. Leflunomide is safe and well tolerated and no unexpected adverse events were noted during the 2 year period; diarrhea, nausea, and alopecia were less frequent with continued treatment.

CONCLUSION

These longterm data confirm leflunomide improves functional ability as shown by reductions in HAQ scores. The benefit of leflunomide is reflected in other efficacy criteria, such as global assessments and the American College of Rheumatology response rates, all of which showed significantly more improvement with leflunomide than sulfasalazine at 24 months.

Racehorse injuries, clinical problems and fatalities recorded on British racecourses from flat racing and National Hunt racing during 1996, 1997 and 1998

For improvements to the safety and welfare of racehorses to be possible, it is essential to have access to basic descriptive information about the veterinary incidents encountered during horseracing. A 3 year surveillance study (1996-1998) was conducted by The Jockey Club into racing injuries, other postrace clinical problems and fatalities from all 59 British racecourses (mainland Britain only) to identify risk factors. During the survey there were 222,993 racing starts: 106,897 starts in flat races on turf (47.9%), 26,519 starts in flat races on all-weather surfaces (11.9%), 30,932 starts in chases on turf (13.9%), 51,786 starts in hurdle races on turf (23.2%) and 6,859 starts in National Hunt flat races (3.1%). Information was recorded about age of horses, racing surfaces and clinical events observed or attended by a veterinary team of 2 clinicians and one veterinary surgeon employed by the racing authority. Of the 2358 clinical events reported (1.05% of all starts), 1937 involved the musculoskeletal system and 421 involved other body systems. Six hundred and fifty-seven incidents (0.29% of starts) resulted in death or euthanasia. Eighty-one percent of limb injury reports involved forelimbs and 46% involved flexor tendons/suspensory ligaments. Nonlimb problems included epistaxis (0.83/1000 starts), 'exhausted horse syndrome' (0.47/1000 starts) and paroxysmal atrial fibrillation (0.20/1000 starts). Incidents including fatalities per 1000 starts were 24.7 from chases, 19.45 from hurdle races, 8.46 from National Hunt flat races and 3.97 from flat races. The overall tendon injury was higher in chases than in hurdle races, even though age-specific rates of tendon injury were higher in hurdle races than in chases. The risk of injuries per start increased significantly with age, while softer racing surfaces were associated with fewer fatalities and injuries than firmer surfaces. The survey described in this paper has provided an up-to-date description of the fatal and non-fatal horseracing incidents under conditions on mainland Britain, enabling progress to be made towards improving the safety and welfare of racehorses.

A novel method for counting eimerian oocysts at very low concentrations in aqueous suspensions

A novel method for counting eimerian oocysts in samples of drinking water has been developed to fulfil the need for monitoring the delivery of very low concentrations of live anticoccidial vaccines to poultry via pipeline nipple-drinker systems. Advantages of the method are the ease of sample collection and processing, high degrees of accuracy and precision, and a sensitivity of one oocyst ml(-1). Results of a validation test are presented, with a protocol for the method and notes on its use. The coefficient of variation (CoV) of 10 sets of oocyst counts with nominal means of 10 to 160 oocysts ml(-1)ranged from about 16 per cent down to 6 per cent. The recovery efficiency for all 100 validation counts averaged 100.2 per cent with a range of 70-130 per cent. A practical example of field use of the method is given, including a modification to decrease the time taken for counting. In this case, when oocysts were pumped around a pipeline circuit of 129 m for 2.5 hours, the CoV of a mean of 112 oocysts ml(-1)(n = 10) was 12.4 per cent.