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B J Allan

Publications and source records attributed to B J Allan.

At least 19 recordsLinked to original sources
PubMed2006

An experimental and theoretical study of the reactions OIO+NO and OIO+OH.

The kinetics of the reaction OIO+NO were studied by pulsed laser photolysis/time-resolved cavity ring-down spectroscopy, yielding k(235-320 K)=7.6(+4.0)(-3.1) x 10(-13) exp[(607+/-128)/T] cm3 molecule-1 s-1. Quantum calculations on the OIO+NO potential-energy surface show that the reactants form a weakly bound OIONO intermediate, which then dissociates to the products IO+NO2. Rice-Ramsberger-Kassel-Markus (RRKM) calculations on this surface are in good accord with the experimental result. The most stable potential product, IONO2, cannot form because of the significant rearrangement of OIONO that would be required. The reaction OIO+OH was then investigated by quantum calculations of the relevant stationary points on its potential-energy surface. The very stable HOIO2 molecule can form by direct recombination, but the bimolecular reaction channels to HO2+IO and HOI+O2 are closed because of significant energy barriers. RRKM calculations of the HOIO2 recombination rate coefficient yield krec,0=1.5x10(-27) (T/300 K)(-3.93) cm6 molecule-2 s-1, krec,infinity=5.5x10(-10) exp(46/T) cm3 molecule-1 s-1, and Fc=0.30. The rate coefficients of both reactions are fast enough around 290 K and 1 atm pressure for these reactions to play a potentially important role in the gas phase and aerosol chemistry in the marine boundary layer of the atmosphere.

Journal Article↗
PubMed2001

Phenotypic and genotypic characterization of virulence factors of Escherichia coli isolated from broiler chickens with simultaneous occurrence of cellulitis and other colibacillosis lesions.

The objective of this study was to characterize virulence factors of Escherichia coli isolates from broilers with simultaneous occurrence of cellulitis and other colibacillosis lesions. Thirty flocks were sampled and 237 birds with cellulitis were examined. Eighty-two (34.6%) of 237 birds condemned for cellulitis had gross lesions in the heart, air sacs, joints, or liver. In 58 chickens, E. coli was isolated from both the cellulitis and other lesions of colibacillosis, and 18.9% of the E. coli isolates from the 2 types of lesions belonged to the same O group. Escherichia coli of serogroups O78, O1, and O2 predominated. Isolates of the same serogroup that were derived from different lesions in the same birds had similar patterns of biotype, aerobactin production, serum sensitivity profile, antibiotic sensitivity, and K1 capsule production. Escherichia coli derived from cellulitis lesions produced virulence factors similar to those found in E. coli isolated from other colibacillosis lesions in poultry.

Animals↗
PubMed2000

Studies on cellulitis and other disease syndromes caused by Escherichia coli in broilers in Sri Lanka.

Cellulitis caused by Escherichia coli in broilers results in substantial losses to the broiler industry in North America and Europe due to condemnations at slaughter. The objective of this study was to identify cellulitis in broilers in Sri Lanka and to characterize the E. coli from cellulitis and other colibacillosis lesions. Twenty-four farms from the low- and mid-country were selected and bacterial isolations were obtained from 241 birds. Two hundred and ninety-one gross lesions were observed in these 241 birds and 162 E. coli isolates were obtained. Cellulitis was observed in 21% of the birds. Twenty-one per cent of the birds had multiple lesions due to E. coli. The frequency of detection of other disease syndromes was 162 (67%) birds with pericarditis, 26 (11%) airsacculitis, 24 (10%) hepatitis, 12 (5%) perihepatitis, and 16 (7%) polyserositis (a combination of pericarditis, perihepatitis and airsacculitis). Serogroups O78, O2, O85 and O88 were distributed among the 32% of typable E. coli and 81% of isolates were assigned to three biotypes. Forty-four per cent of the E. coli isolates produced aerobactin and 88% demonstrated resistance to the bactericidal effect of normal chicken serum. The majority of the E. coli isolates were resistant to the antibiotics commonly used in poultry. All the E. coli isolates were non-haemolytic and 25% of the isolates produced K1 capsule. This study demonstrated the presence of cellulitis in Sri Lanka and this report describes some of the phenotypic characteristics of the E. coli isolates.

Animals↗
PubMed1997

Isolation of Escherichia coli from cellulitis and other lesions of the same bird in broilers at slaughter.

Cellulitis results in substantial losses to the broiler industry due to condemnations at slaughter. This study was conducted to clarify the association between Escherichia coli isolated from cellulitis and other lesions caused by E. coli in individual birds. Fourteen flocks were sampled and 118 birds with cellulitis were examined. Escherichia coli was isolated from all but 2 of the cellulitis lesions, and serogroups O78, O1, and O2 predominated. Thirty-six birds had at least 1 other lesion in addition to the cellulitis lesion. Isolation of E. coli from cellulitis and other lesions occurred in 7 of the 14 flocks. Escherichia coli of the same serogroup were isolated from cellulitis and other lesions in some birds, suggesting that a single E. coli may sometimes be responsible for both types of lesions.

Animals↗
PubMed1994

A carAB mutant of avian pathogenic Escherichia coli serogroup O2 is attenuated and effective as a live oral vaccine against colibacillosis in turkeys.

Colibacillosis is a serious and economically important disease of the respiratory tract of chickens and turkeys. The serogroups of Escherichia coli commonly associated with colibacillosis in poultry are O1, O2, and O78. Although previous attempts to develop a vaccine have not been very successful, vaccination is still considered the most effective way of controlling the disease. Therefore, our laboratory has been involved in the development of an attenuated live vaccine that will be effective in the prevention of colibacillosis. The carAB operon coding for carbamoyl-phosphate synthetase, an essential enzyme in arginine and pyrimidine metabolism, was selected for study. Generalized transduction was used to transfer a Tn10-generated mutation from a laboratory strain to virulent avian field isolates of E. coli. Molecular techniques were used to determine the point of Tn10 insertion within the carAB operon. The insertion mutants were then cured of the tetracycline resistance gene of the transposon to select for antibiotic-sensitive and stable carAB mutants. The degree of attenuation obtained by the mutation was determined in day-old chickens. Typically, when 100-fold the 50% lethal dose (for the wild type) was given, no more than 50% mortality in the day-old chickens was observed. The deletion mutant of serotype O2 was also found to be avirulent in turkeys rendered susceptible to infection with hemorrhagic enteritis virus A. Turkey poults vaccinated orally at 4 weeks old with either the wild-type E. coli EC317 strain or its carAB mutant EC751 were completely protected from infection following challenge with the homologous wild-type strain. Our data indicate that carAB mutants of virulent avian strains of E. coli will be effective and safe as live oral vaccines for prevention of colibacillosis in poultry.

Administration, Oral↗
PubMed1994

Cloning of the early promoters of Pseudomonas aeruginosa bacteriophage D3: sequence of the immunity region of D3.

The early promoters of bacteriophage D3 of Pseudomonas aeruginosa were cloned and physically mapped to the right 25% of the phage genome. The promoters were cloned into promoter selection vector pQF26, and their relative strengths, the direction of transcription, and whether they were directly regulated by repressor were determined. A 3.3-kb fragment of the genome containing the immunity region was sequenced and analyzed (GenBank accession number: L22692). The promoter activity associated with this region was determined to be bidirectional and repressible, indicating that this region contains operator-promoter complexes. Sequence and functional analyses suggest that this region is analogous to the immunity region of coliphage lambda. Two strong promoters, one of which was repressible, were found to be located adjacent to the immunity region. Clear-plaque mutant phage D3c contains insertion element IS222, which causes it to behave as a repressor-negative (c1) variant. The site of insertion of IS222 was sequenced and determined to lie within the c1 gene open reading frame. This phage shows remarkable similarity in genomic organization to coliphage lambda and its relatives.

Amino Acid Sequence↗
PubMed1993

Characterization of Escherichia coli isolated from cases of avian colibacillosis.

Forty-four western Canadian isolates of Escherichia coli associated with colibacillosis of turkeys and chickens were examined for serotype, antibiotic resistance, and production of aerobactin. The isolates belonged to fourteen O serogroups, with 39% of the strains being non-typeable. A high frequency of resistance to tetracycline, kanamycin, neomycin, cephalothin, streptomycin and erythromycin was observed. Most isolates produced aerobactin. Ten E. coli belonging to serogroups O1, O2 and O78 were also examined for pili production, hemagglutination, serum sensitivity, production of iron-regulated outer membrane proteins (IROMPS), and virulence. All isolates examined produced pili, exhibited mannose-sensitive hemagglutination of avian red blood cells and produced IROMPS under iron-restricted growth conditions. The five isolates of serogroup O1 and O2 were resistant to killing by turkey serum and were highly virulent. Only two of the five isolates of serogroup O78 were serum resistant. No correlation between serum resistance and virulence was observed in serogroup O78.

Animals↗
PubMed1990

Cyclic nucleotide responses in control and cystic fibrosis labial glands.

Adenosine 3',5'-cyclic monophosphate (cAMP) and guanosine 3',5'-cyclic monophosphate (cGMP) levels were measured in labial gland slices from controls and patients with cystic fibrosis (CF). Incubation in vitro with 10 microM epinephrine, 50 microM isoproterenol, or 10 microM carbachol increased cAMP levels by 2.3-fold, 3.1-fold, and 1.8-fold, respectively, in control glands and by similar amounts in CF glands. The only statistically significant CF-related difference was a decreased response to isoproterenol. Addition of MIX (3-isobutyl-1-methylxanthine) increased cAMP levels in control and CF glands by an order of magnitude under all conditions but did not eliminate the CF-related decrease in cAMP level obtained with isoproterenol. cGMP levels were measured only in the presence of MIX. Incubation with carbachol nearly doubled cGMP levels in control and CF glands but only the control gland response approached statistical significance (P = 0.06). cGMP levels in CF glands were nearly threefold greater than those in control glands, and disease-related differences obtained in the presence of carbachol and isoproterenol were statistically significant.

1-Methyl-3-isobutylxanthine↗
PubMed1989

Characterization of the genome of Pseudomonas aeruginosa bacteriophage phi PLS27 with particular reference to the ends of the DNA.

The DNA of Pseudomonas aeruginosa rough-specific bacteriophage phi PLS27 was studied. The genome size as determined by summing the sizes of restriction fragments was 42.7 kilobase pairs. Of particular interest was the fact that the DNA was insensitive to certain common restriction endonucleases including EcoRI, BamHI, and HindIII. The ends of the phage DNA were cloned and sequenced, revealing direct repeats of 318 nucleotides. The left end of the genome when cloned into the promoter selection vector pKK232-8 exhibited promoter activity in Escherichia coli. Two promoters bearing greater than 70% sequence homology to the plasmid pNM74 TOL operon and PAK pilin promoters were identified.

Bacteriophages↗
PubMed1989

Potassium release in labial glands from controls and patients with cystic fibrosis.

Labial glands from patients with cystic fibrosis (CF) were tested for a disease-related decrease in cholinergically-induced K release. Labial gland slices from normal controls and patients with cystic fibrosis were incubated in vitro in the presence or absence of cholinergic and adrenergic agonists and with or without a phosphodiesterase inhibitor. Both control and CF glands released K in response to cholinergic stimulation only; no K release response was detected to alpha- or beta- adrenergic stimulation. In contrast to previous results reported for parotid glands, no CF-related decrease in cholinergically-induced K release was detected. Both normal and CF glands released significantly less K with carbachol stimulation in the presence of the phosphodiesterase inhibitor. Overall, the results suggest considerable interglandular differences in disease sensitivity and functional regulation of K release.

1-Methyl-3-isobutylxanthine↗
PubMed1985

Human pancreatic secretory protein profiles in pancreas cancer and chronic pancreatitis.

Pancreatic secretory protein profiles differed significantly between patients with chronic pancreatitis (CP) and pancreatic carcinoma (CA). Specific regions of the patterns were altered when CP versus CA and when CP versus normals were compared. Bands isoelectric in the region of pH 9-11 were elevated in CP. The possible identification of this band as lactoferrin is discussed.

Chronic Disease↗
PubMed1983

Human pancreatic secretory protein profiles in the search for tumor markers.

Pancreatic cancer secretory protein profiles were shown to be different from normals by a microcomputer-assisted analysis of isoelectric focusing patterns. Two acidic protein band regions (pI 3.0 and 4.5) of the pancreatic carcinoma profiles were significantly increased, and eight protein bands (pI 3.7, 5.0, 5.5, 6.5, 6.9, 7.3, 8.0, greater than 10.0) were significantly decreased. Highly significant decreases occurred at pH 7.3 (chymotrypsinogen) and at pH 5.0 (procarboxypeptidase Al, DNase I) in nonactivated specimens. The ratio between the absorbance points at 2.08 and 2.63 cm from the anode in each protein pattern differentiated the pancreas cancer specimens from the control group. Profiles found for the control group gave pI values similar to those found in the literature. The potential value of these findings in the search for tumor markers warrants further investigation as to whether these specimens can be differentiated from those from chronic pancreatitis patients.

Carcinoma↗
PubMed1983

TIBIAS--a microcomputer-based analysis system for isoelectric focusing and electrophoretic patterns.

A program is described for a computer-aided analysis system for isoelectric focusing (IEF) patterns. This system is primarily aimed at comparing and statistically analyzing large numbers of one-dimensional electrofocusing patterns in the search for specific tumor markers in pancreatic ductal secretions. It is designed to collect raw densitometric data, allow interactive processing, matching and statistical tests, and prepare high-quality plots of data at various stages.

Computers↗
PubMed1983

Characterization of tetracycline resistance plasmids from Campylobacter jejuni and Campylobacter coli.

Tetracycline resistance in strains of Campylobacter jejuni and Campylobacter coli was mediated by plasmids. Intra- and interspecies transfer was demonstrated within the genus Campylobacter. Buoyant densities of plasmid DNAs ranged from 1.691 to 1.694 g/cm3 (31 to 33% guanine plus cytosine). Restriction enzymes AccI, BclI, BglII, and PstI were found to be most useful for comparing the plasmids. The molecular weight of C. jejuni plasmid pMAK175 was 44.7 kilobases (29 X 10(6), and the other plasmids had similar sizes. Two plasmids from Belgian isolates of C. coli of human origin had very similar restriction enzyme profiles and are probably identical. Plasmids from human isolates of C. jejuni originating in Canada and the animal isolate of C. coli showed greater diversity. DNA homology among the campylobacter plasmids was assessed by probing the digests with a nick-translated campylobacter plasmid, pMAK175. All restriction fragments showed significant homology with pMAK175 probe DNA. No homology was noted between campylobacter plasmid DNA and plasmids specifying the four classes of tetracycline resistance determinants found in Enterobacteriaceae.

Campylobacter↗
PubMed1982

Protein secretions in hamsters with pancreatic carcinoma.

Pancreatic secretions from the hamster model for pancreatic ductal adenocarcinoma were analyzed to determine whether alterations had occurred in the protein composition. CCK-and secretin-stimulated secretions were collected from 13 animals with cancer and 16 normal controls. Subsequent separation of the proteins by isoelectric focusing showed the following: (1) Significant changes occurred in the protein composition from animals with carcinoma. An unusually dark band was present at pH 7.5 just below amylase (pH 7.65); two unidentified bands, present in the normals at pH 6.9 and 7.0, were missing; and marked decreases occurred in the cathodic proteins with isoelectric points above pH 9, (2) CCK provided the optimal stimulus for differentiating specimens from animals with carcinoma from the normal controls. (3) The protein concentrations of CCK-stimulated secretions of animals with carcinoma were significantly lower than the controls. We have concluded that the protein alterations which have occurred in the hamster model for pancreatic ductal adenocarcinoma warrant further investigation.

Animals↗
PubMed1982

Mutational enzymatic resistance of Enterobacter species to beta-lactam antibiotics.

Mutants with enhanced beta-lactam resistance were selected from strains of Enterobacter cloacae and E. aerogenes by using three antibiotics. High-level beta-lactamase-producing mutants had similar degrees of increased resistance, enzyme substrate profiles, and isoelectric (pI) values irrespective of the selective agent. Reverse mutants from a resistant E. cloacae mutant regained the susceptibility pattern originally exhibited by the wild type, or were of enhanced susceptibility, and no longer expressed increased beta-lactamase production. beta-Lactamases of the mutants were similar in pI values to the wild-type enzyme. The increased resistance of the mutants therefore appeared to be accounted for by increased beta-lactamase production.

Anti-Bacterial Agents↗