Improved accuracy and robustness of electron density profiles from JET's X-mode frequency-modulated continuous-wave reflectometers.

JET's frequency-modulated continuous wave (FMCW) reflectometers have been operating well with the current design since 2005, and density profiles have been automatically calculated intershot since then. However, the calculated profiles had long suffered from several shortcomings: poor agreement with other diagnostics, sometimes inappropriately moving radially by several centimeters, elevated levels of radial jitter, and persistent wriggles (strong unphysical oscillations). In this research, several techniques are applied to the reflectometry data analysis, and the shortcomings are significantly improved. Starting with improving the equilibrium reconstruction that estimates the background magnetic field, adding a ripple correction in the reconstructed magnetic field profile, and adding new inner-wall reflection positions estimated through ray-tracing, these changes not only improve the agreement of reconstructed profiles to other diagnostics but also solve density profile wriggles that were present during band transitions. Other smaller but also persistent wriggles were also suppressed by applying a localized correction to the measured beat frequency where persistent oscillations are present. Finally, the burst analysis method, as introduced by Varela et al. [Nucl. Fusion 46 S693 (2006)], has been implemented to extract the beat frequency from stacked spectrograms. Due to the strong suppression of spurious reflections, the radial jitter that sometimes would span several centimeters has been strongly reduced. The stacking of spectrograms has also been shown to be very useful for stacking recurring events, like small gas puff modulations, and extracting transport coefficients that would otherwise be below the noise level.

Attenuation of a virulent type 2 bovine viral diarrhea virus.

The purpose of this study was to produce an attenuated bovine viral diarrhea virus (BVDV) type 2 strain as a tool for identifying potential virulence markers in the BVDV2 genome. The attenuation of the virulent strain, BVDV2-24515, was accomplished by in vivo and in vitro passage. The strain was initially used to infect an elk (Cervus elaphus) [J. Wildl. Dis. 35 (1999) 671], re-isolated at 7 days post-inoculation from serum, and then subsequently passaged 56 times in cell culture. Two groups of calves were inoculated intranasally with either BVDV2-24515 or the putative attenuated virus, designated BVDV2-LATT. Calves inoculated with BVDV2-24515 had cumulative clinical scores which ranged from 6 to 53. Clinical signs in these calves consisted of anorexia, depression, dehydration, diarrhea (+/-bloody), and pneumonia. Several calves developed leukocytopenia, primarily a neutrocytopenia, and presented lesions of enteritis or pneumonia at necropsy. In contrast, cattle inoculated with BVDV2-LATT had cumulative clinical scores which ranged from 0 to 2. This was not significantly different from that of controls which received no virus (range: 0-1). Calves inoculated with BVDV2-LATT produced high neutralizing antibody titers against BVDV2. Thus, in addition to its potential use as a tool for identifying virulence markers, the attenuated virus is also worthy of further study as a candidate virus for inclusion in a modified-live vaccine.

Effect on hematopoietic tissue of experimental infection of calves with noncytopathic type 2 bovine viral diarrhea virus.

To investigate the hematologic abnormalities observed with noncytopathic type 2 bovine viral diarrhea virus (ncpBVDV-2), calves 6 to 8 mo old were inoculated with an isolate of either high virulence (HV24515) or low virulence (LV11Q); control animals received the same volume of uninfected cell-culture supernatant. Peripheral blood neutrophil, lymphocyte, and platelet counts decreased in all the virus-inoculated calves but were significantly lower and remained decreased longer in the calves given HV24515. For each isolate, a decrease in the number of mature myeloid cells in the bone marrow coincided with the development of neutropenia, but the depletion persisted significantly longer (4 to 6 d) in the calves given HV24515. In the bone marrow of calves given LV11Q, the number of proliferating myeloid cells increased in proportion to the decrease in the number of mature myeloid cells. In the calves inoculated with HV24515, BVDV antigen was observed in bone marrow cells when the peripheral blood counts were lowest. Megakaryocytes were the predominant cell type exhibiting positive BVDV staining; myeloid cells rarely stained positively. Viral antigen was not observed in the bone marrow of calves given LV11Q. These experiments demonstrated that ncpBVDV-2 isolates of both high and low virulence caused decreased leukocyte and platelet counts, but only the high-virulence HV24515 isolate caused a delay in the production of myeloid proliferating cells. The delay may contribute to the ability of certain ncpBVDV-2 isolates to induce severe disease.

A comparison of polymerase chain reaction with and without RNA extraction and virus isolation for detection of bovine viral diarrhea virus in young calves.

Previously, the authors described a multiplex reverse transcriptase-polymerase chain reaction (PCR) assay for detection and typing of bovine viral diarrhea virus (BVDV) from blood of persistently infected (PI) cattle that could be used with or without RNA extraction. In the present study, the PCR assay was evaluated for its ability to detect BVDV in young calves as a screening tool for detection of persistent infections. Both methods, PCR after RNA extraction (rPCR) and the direct method without RNA extraction (dPCR) were applied and compared with virus isolation (VI) with diagnostic specimens. From 450 whole blood samples from Ontario calves, 47 and 39 samples were positive by rPCR and VI, respectively. From the 47 samples positive by rPCR, 45 (96%) also were positive by dPCR when samples were tested both undiluted and diluted 1:10. In comparison to VI, the relative sensitivities of both PCR assays were 100%. Examination of the results indicates that both PCR assays can be used for screening calves for persistent infection with BVDV.

Early diagnosis of Murray Valley encephalitis by reverse transcriptase-polymerase chain reaction.

A 4-year-old aboriginal boy developed encephalitis due to Murray Valley encephalitis virus (MVE) following an earlier infection with Kunjin virus (KUN). The illness was severe, resulting in cerebral atrophy and profound physical and intellectual disability. The earlier KUN infection complicated his serological profile and delayed antibody responses to MVE. By contrast, the reverse transcriptase-polymerase chain reaction (RT-PCR) assay detected MVE in serum 3 days after the onset of illness and 4 days before the appearance of MVE-specific IgM. We suggest that MVE-specific RT-PCR provides rapid and specific diagnosis of MVE and should be used more widely for the diagnosis of acute viral encephalitis in cases originating from flavivirus endemic areas.

A descriptive study of the frequency and characteristics of proliferative enteropathy in swine in Ontario by analyzing routine animal health surveillance data.

Routine surveillance data, collected on pathology submissions at the Animal Health Laboratory in Guelph between 1992 and 1997, were analyzed to determine demographic, clinical, and pathologic characteristics of cases of proliferative enteropathy and the frequency of this condition relative to other infectious enteric diseases in swine in Ontario. The most commonly reported disease was Escherichia coli enteritis (average cases/year = 70.0). Among infectious enteropathies that occur typically in neonatal pigs, coccidiosis (28.4 cases/year) and rotaviral enteritis (5.6 cases/year) were reported. Among infectious enteropathies generally associated with diarrhea in weaner and grower/finisher pigs, the most frequently reported was proliferative enteropathy (27.6 cases/year), followed by swine dysentery (23.3 cases/year), transmissible gastroenteritis (19.6 cases/year), and salmonellosis (8.4 cases/year). Diarrhea and bloody diarrhea were reported in 29% and 31%, respectively, of herds diagnosed with proliferative enteropathy. Important gross intestinal lesions included mucosal hypertrophy (62% of cases), hemorrhage (47%), and mucosal necrosis (34%). Histologic intestinal lesions included epithelial hyperplasia (90% of cases), mucosal necrosis (59%), and inflammation (49%). Our results suggest that proliferative enteropathy is a major infectious enteric disease in grower/finisher pigs in Ontario.

Viremia and virus shedding in elk infected with type 1 and virulent type 2 bovine viral diarrhea virus.

In order to determine whether elk (Cervus elaphus) could be infected with and shed bovine viral diarrhea virus (BVDV) and to determine whether BVDV could cause disease in elk, two groups of five yearling elk each and two control cattle were experimentally inoculated intranasally with type 1 Singer strain or a virulent type 2 isolate of BVDV, strain 24515. Virulence of the type 2 isolate was confirmed by inoculation of a control bovine cow which developed diarrhea, dehydration, severe thrombocytopenia, hemorrhages, and enteritis with intestinal necrosis. None of the elk inoculated with type 1 or type 2 BVDV developed clinical signs of illness. However, all elk became infected as demonstrated by viremia, nasal shedding, and/or seroconversion. One uninoculated, in-contact elk contracted type 1 BVDV and seroconverted. Thus, although BVDV does not appear capable of producing disease in nonpregnant elk, the species is susceptible to infection and can shed and transmit BVDV.

Humoral response and protection from experimental challenge following vaccination of raccoon pups with a modified-live canine distemper virus vaccine.

Eight 8-wk-old raccoon pups (Procyon lotor) with maternal canine distemper virus (CDV) neutralizing antibodies (NAb) and 24 8-wk-old seronegative pups were administered a commercial modified-live CDV vaccine (Galaxy, D, Solvay Animal Health, Inc., Kitchener, Ontario, Canada). All 24 seronegative raccoons had detectable serum CDV NAb titers 14 days after the initial dose. Titers rose to maximum levels 4 wk post-vaccination. Mean titers for groups of vaccinated seronegative pups were maintained between 1:256 and 1:2,048 for the remainder of the 3 mo observation period. Geometric means of the serum CDV NAb titer of eight seronegative pups given a single vaccine dose at 8 wk of age did not differ significantly from those of eight pups that were given serial doses at 8, 12, and 16 wk of age, or from those of eight pups vaccinated once at 16 wk of age. Seven unvaccinated 8-wk-old raccoon pups used as controls remained seronegative throughout the trial. Seven out of eight 8-wk-old pups with maternal antibodies, vaccinated at 8, 12, and 16 wk of age, failed to develop a rise in their CDV NAb titers until at least 18 wk of age, 2 wk after the third vaccination. Titers in eight unvaccinated raccoons with maternal antibodies declined steadily to undetectable levels at 20 wk of age. A half-life of 10.55 days was calculated for maternally-derived CDV NAb in raccoon pups. Sixteen vaccinated raccoons were protected from clinical disease following experimental oronasal challenge with a virulent raccoon strain of CDV, 13 to 23 wk after vaccination. Serum CDV NAb titers at the time of challenge ranged from 1:12 to 1:384 and increased during the period of observation. Three of four unvaccinated seronegative raccoons used as controls failed to mount any detectable CDV NAb and were euthanatized after developing clinical signs of canine distemper 26, 29, and 30 days post-challenge (PC). Necropsies confirmed the diagnosis. The fourth control raccoon exhibited transient equivocal clinical signs, mounted a sluggish humoral response, but was clinically normal when euthanatized 42 days PC. In this raccoon, there was focal non-suppurative encephalitis with intranuclear inclusion bodies typical of CDV infection.

Pathogenesis and clinical signs of equine herpesvirus-1 in experimentally infected ponies in vivo.

Equine herpesvirus-1 (EHV-1) causes respiratory disease, neonatal death, abortion and neurologic disease. The main purpose of this study was to identify viral antigen in respiratory tract samples by immunoperoxidase staining. Six pony foals were selected on the basis of demonstrating seronegativity to EHV-1 by virus neutralization and housed in isolation. They were infected experimentally by administering EHV-1 nebulized ultrasonically through a face mask. Successful infection was clinically apparent as each of the foals had febrile responses, nasal discharge, and enlarged submandibular lymph nodes. Sporadic coughing was also heard. EHV-1 was isolated from nasopharyngeal swabs of 4/6 ponies and seroconversion was demonstrated in all foals. Bronchoscopic examination of the large airways revealed hyperemia. The incidence of recovery of Actinobacillus suis from nasopharyngeal swabs increased initially, with recovery of Streptococcus zooepidemicus isolates predominating at 3 wk post-infection. Cytology brushes were used to sequentially sample the respiratory tract of the infected ponies at the nasopharynx, mid-trachea and the mainstem bronchus. Bronchoalveolar lavage provided lung cells. Immunocytochemistry techniques were applied to both types of samples to locate EHV-1 antigen. Indirect immunoperoxidase staining of samples utilizing monoclonal antibodies specific for EHV-1 demonstrated viral antigen associated with cellular debris, primarily in the nasopharyngeal samples on days 3-9 post-infection.

Study of the duration and distribution of equine influenza virus subtype 2 (H3N8) antigens in experimentally infected ponies in vivo.

The purpose of this experiment was to study the duration and distribution of equine influenza virus in actively infected ponies over a 3 wk period. Pony foals (6-8 mo old) were infected experimentally by nebulizing equine influenza subtype-2 virus ultrasonically through a face mask. Successful infection was clinically apparent as each of the foals (n = 6) had a febrile response, a deep hacking cough and mucopurulent nasal discharge for 7 to 10 d. The virus was isolated from nasopharyngeal swabs of all the ponies 3 and 5 d after infection and all the ponies seroconverted to the virus. Samples were taken from the nasopharynx, mid-trachea and the mainstem bronchus with cytology brushes through an endoscope as well as from bronchoalveolar lavage fluid. On days 3 to 7 post-infection, ciliacytophtorea (the presence of cilia and ciliated plates separated from columnar epithelial cells) was recognized on routine cytological stain. Indirect immunoperoxidase staining utilizing polyclonal antibodies demonstrated viral antigen in intact and fragmented ciliated epithelial cells and in fragments of ciliated plates. The infected cells and cell fragments were particularly evident on days 3 and 5 post-infection in the nasopharynx, mid-trachea and mainstem bronchus and on days 3 to 7 post-infection in the bronchoalveolar lavage samples. On days 7 and 21 post-infection, viral antigen was identified in vacuoles of alveolar macrophage-like cells collected by bronchoalveolar lavage. It can be concluded from this study that equine influenza virus can infect not only the upper airways but also the bronchial epithelium and that viral antigen can persist up to 21 d post-infection.

Primary staphylococcal pneumonia in childhood: a review of 69 cases.

Primary staphylococcal pneumonia is a rapidly progressive illness with well-described clinical and radiological features and a significant mortality rate. This retrospective study of cases diagnosed over a 20 year period at a tertiary paediatric hospital was undertaken to document the epidemiology and assess the management and mortality of the disease. The survey demonstrated that far fewer patients are being seen than formerly and confirmed that this is a disease primarily affecting infants and Aboriginal children. The initial radiological features were not diagnostic in the majority of cases but typical changes appeared in most at some time during the illness. The use of surgical drainage was not associated with a decrease in the duration of fever or length of hospital stay. The mortality rate has improved but remains significant.

Cataracts, aberrant oral frenula, and growth retardation: a new autosomal dominant syndrome.

We report on a mother and her two children with an autosomal dominant cataract syndrome with associated aberrant oral frenula, growth retardation, and specific facial appearance. Their phenotype differs from that of other reported cataract syndromes, and we conclude that this is a previously undescribed entity.

Sporadic, severe bronchointerstitial pneumonia of foals.

Bronchointerstitial pneumonia was diagnosed postmortem in 19 foals in a 10 year retrospective study of submissions to a diagnostic center in Ontario. Mean age at death was 2.0 +/- 0.05 (SEM) mo (range five days to four months). Fourteen of 19 were aged from 1.5 to 2.5 mo. Clinically, the disease was generally characterized by sudden onset of fever and increasingly severe dyspnea which developed into respiratory distress before death. Mean length of illness was 7.0 +/- 0.33 days (range 1-21 days). The disease appeared to affect only individual foals on 19 different farms.At postmortem, lungs were typically diffusely red, wet, firm, and failed to collapse. The major lesion recognized histologically was epithelial necrosis of alveoli and terminal bronchioles. Alveolar lumens contained large epithelioid cells, which were probably macrophages, and multinucleated syncytial cells were present in 16 of the 19 lungs. Inflammatory cells were sparse. Intraalveolar fibrin was prominent in all lungs. Bacteriological examination revealed no significant pathogen in 12 animals, but Rhodococcus equi was isolated from seven foals, associated in two animals with extensive abscesses. Viruses were not recovered from eight foals examined.On the basis of the similarity and severity of lesions, the sporadic nature of the disease, and the similar age at onset which appears to coincide with declining maternally-derived immunoglobulins, we speculate that this disease may be the result of a viral infection.

Unique dwarfing, spondylometaphyseal skeletal dysplasia, with joint laxity and dentinogenesis imperfecta.

We report a 3 1/2-year-old boy with a unique spondylometaphyseal dysplasia with predominantly mesomelic involvement. In addition, he had gross generalised joint laxity and dentinogenesis imperfecta.

Increased paediatric admissions with asthma in Western Australia--a problem of diagnosis?

A study of hospital admissions of paediatric cases with asthma over a 17-year period (1971-1987) in Western Australia was performed retrospectively. Hospital admission rates for asthma increased in all paediatric age-groups with the most dramatic increase occurring in the youngest (zero- to four-years') age-group. This increase in hospital admissions for asthma has been accompanied by a rapid decline in admissions for other paediatric respiratory conditions that share a potential diagnostic overlap with asthma. Hospital admission rates for asthma have reached a plateau at the major paediatric teaching hospital in the State from 1977 and Statewide from 1983. Diagnostic transfer has contributed significantly to the reported increase in hospital admissions for asthma over the past two decades.

What are the mechanisms producing increased ventilation in dead space studies in neonates?

In 21 studies on 15 infants an additional dead space tube produced a significant rise in end-tidal PCO2 and fall in end-tidal PO2, associated with a rise in minute ventilation (228 +/- 77 mL/kg/min at zero, 348 +/- 85 mL/kg/min at one, and 437 +/- 128 mL/kg/min at two anatomical dead spaces). The differences between end-inspiratory and end-expiratory PCO2 and PO2 did not change significantly, suggesting an increase in dead space, but not in alveolar ventilation. In a further 9 babies the rise in ventilation was unchanged when measurements were repeated in 30% oxygen (361 +/- 65 vs. 340 +/- 54 mL/kg/min at one anatomical dead space). Studies on 8 babies, with the added tube ventilated by a fan, showed that a mean 28% of the rise in minute ventilation was due to increased resistance. Although the response to tube breathing in neonates is complex, carbon dioxide appears to be the major factor producing increased ventilation.