Randomized single blind trial of two low-volume bowel preparations for screening computed tomographic colonography.

BACKGROUND: Bowel preparation is an important part of computed tomographic colonography (CTC); we evaluated two small-volume preparations for screening CTC with regard to quality of preparation and patient acceptability. METHODS: Asymptomatic subjects at average risk for colorectal cancer from a community-based CTC screening program were randomized to bowel preparation comprising magnesium/bisacodyl/picolax or polyethylene glycol (PEG)/picolax. CTC images were evaluated by a blinded investigator for residual feces and fluid; subjects completed a questionnaire regarding acceptability of the preparation. RESULTS: In 176 subjects randomized to magnesium/bisacodyl/picolax (n = 82) or PEG/picolax (n = 94), the former preparation was discontinued because of syncope or presyncope in four (5%) subjects. Another 137 subjects received PEG/picolax without a significant adverse event. There were no other major differences in acceptability of the preparations as reported by subjects. The quality of bowel preparations for reporting CTC was similar. CONCLUSION: For subjects having screening CTC, both small-volume bowel preparations are generally well tolerated and result in minimal fluid and fecal residue; however, the magnesium/bisacodyl/picolax preparation was accompanied by an unacceptable incidence of syncope and is no longer used by us.

Detection of Helicobacter pylori antigen in faeces by enzyme immunoassay.

The detection of Helicobacter pylori antigen directly in faecal specimens may offer an alternative non-invasive method for determining the presence of H. pylori infection. This study compared the performance of the Premier Platinum HpSA enzyme immunoassay (HpSA) with histology and CLOtest, a rapid urease test. Of 134 patients undergoing upper gastrointestinal endoscopy, 37 (28%) were H. pylori-positive by histology and CLOtest. Using the HpSA test, H. pylori was detected in 35 H. pylori-positive patients (95% sensitivity) and one H. pylori-negative patient (99% specificity). The positive and negative predictive values for HpSA were 97 and 98%, respectively. HpSA is a rapid, easily performed, non-invasive method for detecting H. pylori.

Virtual colonoscopy compared with conventional colonoscopy: a developing technology.

AIM: To determine the accuracy of computed tomography colography (virtual colonoscopy) in detecting colorectal polyps and colorectal cancer. DESIGN: Blinded comparison of virtual colonoscopy (initially supine-only scans and later supine plus prone scans) with the criterion standard of conventional colonoscopy. SUBJECTS AND SETTING: 100 patients aged 55 years or over referred to a public teaching hospital for colonoscopy, July 1997 to January 2000, because of colonic symptoms or a family history of bowel cancer. MAIN OUTCOME MEASURES: Presence and size of polyps and other lesions; certainty of polyp identification on virtual colonoscopy (on 100-point visual analogue scale); sensitivity and predictive values of virtual colonoscopy. RESULTS: Conventional colonoscopy identifed 121 polyps in 47 patients; 28 of these polyps, in 19 patients, were identified by virtual colonoscopy. Sensitivity of virtual colonoscopy for detecting polyps (using supine plus prone scans) was 73% for polyps with diameter > or = 10 mm (95% CI, 39%-94%) and 19% for smaller polyps (95% CI, 10%-31%) (P < 0.001); corresponding figures for supine-only scans were 57% (95% CI, 18%-90%) and 11% (95% CI, 4%-24%), respectively. Ten polyps identified at virtual colonoscopy were considered false-positive findings (8%). The value of finding a polyp on virtual colonoscopy (with thresholds of 5 mm for diameter and 30 points for certainty score) was assessed as a predictor of finding a polyp (diameter > 5 mm) on conventional colonoscopy. Positive and negative predictive values were 88% and 89%, respectively, for supine plus prone scans. CONCLUSION: Although virtual colonoscopy shows potential as a diagnostic tool for colorectal neoplasia, it is currently not sufficiently sensitive for widespread use.

Temporal relationships of viremia, interferon activity, and antibody responses of sheep infected with several bluetongue virus strains.

Sheep had viremias that were first detected on day 3 (+/- 1) after infection with several strains of bluetongue virus (BTV) representing United States serotypes 10, 11, 13, and 17. Diphasic peaks of infectivity were attained on days 6 and 10 (+/- 2). Interferon (IFN) was first detected in serum samples on day 5 (+/- 1), and reached greatest concentrations on day 6 (+/- 2), which coincided with the first viremic peak; IFN concentrations then decreased toward zero by day 10 (+/- 2). Interferon peak concentrations induced approximately a 90% decrease in virus titer. The decrease in IFN concentrations by day 9 (+/- 2) corresponded with the second viremic peak on day 10 (+/- 2). Onset of the decrease in detectable concentrations of virus after the second peak of viremia corresponded to the initial detection of serum antibody to BTV by day 10 (+/- 2). Virus titer decreased and antibody production increased until approximately days 21 to 28, when the titers plateaued and virus was not detected. Febrile responses peaked on day 7 (+/- 1) during the peak viremic period. The WBC count was depressed at the time the virus titer increased, but returned to normal values while the sheep were still viremic. Diphasic viremias in BTV-infected sheep were attributed to induction of high concentrations of IFN concurrent with the first virus titer peak, followed by production of antibody to specific BTV strains and a subsequent reduction in viremia at the second virus titer peak.

Venezuelan equine encephalomyelitis virus: concentration, partial purification, inactivation and immunogenicity.

Venezuelan equine encephalomyelitis (VEE) TC-84 vaccinal virus, from 10-1. quantities of infected duck embryo fibroblast cell culture fluids, was isolated by combined continuous-flow centrifugation with isopycnic banding in sucrose. Most of the recovered infectivity and hemagglutinating activity were in a single band at a buoyant density (rho) of 1.2. About 90% of the total input protein (450-520 mg) was removed with the effluent, whereas most of the remaining 10% also banded at a rho of 1.2. Infectivity was inactivated with formalin at a final concentration of 0.05% at 37 degrees C for 24 hr. Formalin-inactivated virus retained its immunogenicity and induced VEE virus-specific antibody in horses and guinea pigs. The horses and those guinea pigs that received equivalent doses of vaccine survived after a challenge of their immunity with virulent VEE virus.

Abnormalities and virus-like particles in spermatozoa from bulls latently infected with bluetongue virus.

Abnormalities were commonly observed in spermatozoa, and bluetongue virus (BTV) was isolated from semen of 2 known BTV carrier bulls and 2 of 4 BTV seropositive field bulls. The spermatozoal abnormalities ranged from a small cavity between the acrosome and nucleus with some involvement of the nucleus, to an enlargement of the cavity accompanied by vesiculation that could affect the entire acrosome. Virus-like particles were occasionally observed in the affected spermatozoa, but were present in all samples. A positive relationship was found between infectivity of semen samples from BTV latently infected bulls and the observation of abnormalities and virus-like particles in the heads of affected spermatozoa.

Bluetongue and epizootic hemorrhagic disease virus isolation from vertebrate and invertebrate hosts at a common geographic site.

One serotype of bluetongue virus (BTV) and two serotypes of epizootic hemorrhagic disease virus (EHDV) were isolated from vertebrate and invertebrate hosts on a farm in Colorado. The isolations were from blood samples collected a week apart from a dairy heifer with stomatitis and laminitis; EHDV serotypes 1 and 2 were isolated from the first blood sample, and BTV serotype 13 and EHDV serotype 1 were isolated from the second. Antibodies to EHDV and BTV were detected in the serum from this heifer. Both EHDV serotypes and BTV serotype 13 were isolated from pools of female biting gnats (Culicoides variipennis) that had not had a recent blood meal. The BTV insect isolate was biologically transmitted by female gnats from an infected donor sheep to a recipient host sheep. Culicoides variipennis was the predominant insect collected during three nights of light trap captures at the farm.

Relevance of laboratory colonies of the vector in arbovirus research--Culicoides variipennis and bluetongue.

Relevance for laboratory colonies of Culicoides variipennis (Coquillett) in arbovirus research was determined during colonization by comparing a vector-competence characteristic for the parent (P) field and subsequent colonized generations. Three colonies established in 1972-1973 were used to determine whether each was representative of the field population from which it was derived for oral infection to 2 to 4 serotypes of bluetongue virus (BTV). Two colonies that were based on small numbers of females ovipositing did not represent the field population. Both appeared homogeneous to oral infection with different serotypes, and one was resistant to infection whereas the other was susceptible. The third colony, which was based on about 150 P females that had oviposited, was more representative of the field population: 1) oral susceptibility to BTV for the F6 was not greatly different from that of the P generation, and 2) the colony retained some heterogeneity for response to oral infection with different serotypes of BTV. The number and percentage of P females ovipositing and the numerical growth factor from the P to F1 were used to estimate whether a laboratory colony was apt to represent the field population from which it was derived.

Heterogeneity of Culicoides variipennis field populations to oral infection with bluetongue virus.

A standard colonized population (000 line) of Culicoides variipennis (Coquillett) was used as the control for comparing the infection rate (IR) responses of different field populations of the vector to oral infection with several strains of bluetongue virus (BTV) that belonged to four serotypes. Three field populations from Colorado and Oregon tested concurrently in 1969 were differently susceptible to three BTV strains representing three serotypes. The IR's of each of the three populations varied greatly for the three serotypes, and the lowest IR for each of two Colorado populations was for a different serotype. The IR's of different populations to the same BTV strain varied greatly, and the lowest and highest IR's for two serotypes with adequate virus concentration occurred in different populations. Two Kentucky field populations in 1971 were completely resistent to oral infection with a BTV strain; in 1972, one population remained resistant and the other became moderately susceptible. The IR's of different field populations in 1971 to a single BTV strain ranged from 0 to 68%. The IR's of an Idaho population to three BTV strains representing three serotypes showed that a susceptibility rate (SR) could be calculated if the IR's were similar for one and for two infective blood meals. The average SR of this population was 42%; the SR's to each serotype were 32%, 40%, and 54%, with the highest response for the serotype that included the BTV strain collected during the BT outbreak from which the vector population was also collected.

Continuity of the dsRNA genome of bluetongue virus.

The duplex RNA genome of bluetongue virus, extracted under acidic conditions with sodium dodecyl sulfate and phenol, is an unfragmented continuous structure. Most genomes appeared as a rosette with 10 loops (genes) emanating from a central crescent- or doughnutshaped area. The genome has a mean length of ca. 10 µm which corresponds to a molecular weight of ca. 23 million.

Culicoides, the vector of epizootic hemorrhagic disease in white-tailed deer in Kentucky in 1971.

The biting gnat, Culicoides variipennis (Coquillett), was shown to be a vector of epizootic hemorrhagic disease (EHD) in white-tailed deer, Odocoileus virginianus, in Kentucky because of virus isolations from parous females. Epidemiological evidence showed a close relationship of this vector to the animal host during an outbreak of EHD in penned deer. Larval breeding sites of C. variipennis were found and C. variipennis was the most abundant biting fly present during the outbreak. Females of C. variipennis were commonly observed biting deer, swine, cattle and, occasionally, man.

Transmission of two strains of epizootic hemorrhagic disease virus in deer by Culicoides variipennis.

Two strains of epizootic hemorrhagic disease virus (EHDV), New Jersey (NJ) and Kentucky (KY), of deer were biologically transmitted between white-tailed deer, Odocoileus virginianus, by Culicoides variipennis. The KY strain, isolated from C. variipennis collected during an epizootic in deer, was identified as EHDV by serological tests. Deer exposed to the KY or the NJ strains of EHDV developed an acute hemorrhagic disease; most deer died 6 to 13 days after infection. Sheep inoculated with EHDV developed no clinical signs of disease.