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S Dawson

Publications and source records attributed to S Dawson.

At least 37 records · Page 2Linked to original sources
PubMed2001

Molecular analysis of isolates of feline calicivirus from a population of cats in a rescue shelter.

Two visits, six weeks apart, were made to a cat rescue shelter and single oropharyngeal swabs were taken from all the compliant cats. Feline calicivirus was isolated from 14 of 45 swabs (31 per cent) taken on the first visit and 12 of 46 swabs (26 per cent) taken on the second visit. Nucleotide sequences were obtained for nine isolates from the first visit, six isolates from the second visit, and for the vaccine virus used in the cattery. Distance analysis showed that the majority of the isolates could be assigned to one of two groups. All the isolates obtained from cats sharing the same pen or isolates obtained from the same cat on successive visits, were less than 5 per cent distant, whereas most of the isolates from cats in different pens were more than 20 per cent distant. Phylogenetic analysis showed that at least seven distinct field isolates were present in the cattery. The only good evidence for virus transmission within the cattery was a case in which two viruses isolated from cats in different pens had sequences that were less than 5 per cent distant.

Animals↗
PubMed2001

Endemic infection of a cat colony with a feline calicivirus closely related to an isolate used in live attenuated vaccines.

We have typed three feline calicivirus (FCV) isolates obtained over a 5-month-period from an endemically infected cat colony. Sequence analysis from variable region E of the capsid gene from these isolates strongly suggests they are minor variants of a single FCV strain, and that this strain is closely related to the one used in many live-attenuated FCV vaccines. Such a vaccine was last used approximately 2 months before the first of the isolates in this study was obtained. Sequence differences between the 'colony isolate' and the vaccine virus suggest that the colony virus has evolved from the vaccine virus and was persisting in the colony. The extent to which vaccine virus may contribute to the continued high prevalence of FCV needs to be determined.

Animals↗
PubMed2001

Purification of poly-ubiquitinated proteins by S5a-affinity chromatography.

Poly-ubiquitination, the post-translational covalent conjugation of isopeptide-linked chains of ubiquitin to other target proteins, is the central signal for proteolytic degradation by the 26S proteasome complex. The S5a subunit of the 26S proteasome binds poly-ubiquitin chains containing four or more ubiquitins. We have used an immobilised glutathione-S-transferase (GST)-S5a fusion protein to purify poly-ubiquitinated proteins from mammalian tissues, with the intention of expanding the repertoire of known substrates of the ubiquitin pathway. A complex mixture of poly-ubiquitinated proteins was successfully purified from normal pig brain extract following induction of in vitro ubiquitination. Western blots of two-dimensional gels of this mixture showed at least two diagonal series of ubiquitin-positive spots. Individual spots in each series were separated by approximately 9 kDa suggesting that they represent poly-ubiquitinated proteins with increasing numbers of ubiquitins in the chains. S5a-binding proteins purified from ubiquitination-induced human placental extracts, resolved by sodium dodecyl sulfate polyacrylamide gel electrophoresis and visualised by Coomassie staining, contained a single major species with an apparent denatured molecular mass of approximately 60 kDa. Edman degradation identified this protein as hHR23B, a human homologue of the Saccharomyces cerevisiae DNA repair protein Rad23p. In this case hHR23B is not ubiquitinated but instead contains an intrinsic ubiquitin-like domain at its N-terminus, through which it interacts with S5a (Hiyama, H., et al., J Biol. Chem. 1999, 274, 28,019-28,025).

Animals↗
PubMed2001

Use of temporal temperature gradient gel electrophoresis to identify flaA and fim3 sequence types in Bordetella bronchiseptica.

AIMS: The aim of this study was to develop an approach to detect variation in the flaA and fim3 genes amongst animal isolates of Bordetella bronchiseptica using temporal temperature gradient gel electrophoresis (TTGE). METHODS AND RESULTS: Amplicons representing three flaA and two fim3 sequence types were subjected to TTGE analysis. It was possible to distinguish clearly between each of the sequence types using TTGE. CONCLUSION: This suggests that TTGE could be a useful tool for studying the epidemiology of B. bronchiseptica. SIGNIFICANCE AND IMPACT OF THE STUDY: PCR amplification coupled to TTGE offers a general method for the rapid screening of large numbers of microbial strains for variations in gene sequences.

Animal Population Groups↗
PubMed2001

A field trial to assess the effect of vaccination against feline herpesvirus, feline calicivirus and feline panleucopenia virus in 6-week-old kittens.

A trivalent (feline panleucopenia, feline herpesvirus, feline calicivirus), modified live, commercially available cat vaccine was used at either 6, 9 and 12 weeks of age (early schedule) or 9 and 12 weeks of age (conventional schedule), and the serological response to vaccination was assessed. The level of maternally derived antibody present at 6 weeks of age was also established. The use of early vaccination at 6 weeks of age induced an antibody response to each virus by 9 weeks of age in a significant proportion of kittens compared with unvaccinated littermates. There was no difference between the conventionally and early-vaccinated groups in terms of antibody response to any antigen by 12 and 15 weeks of age.

Age Factors↗
PubMed2001

Epidural catheter infections.

Epidural analgesia is used as a method of pain relief throughout the UK. It is used short-term in obstetric practice, following surgery and after trauma, and also longer-term for malignancy and chronic pain. Infection may occur as a complication of the technique. Both deep infection, e.g., meningitis, paraspinal and epidural abscesses, and superficial skin infections can occur. To minimize infection risk, epidural catheters should be inserted using an aseptic technique and subsequently checked at least daily, looking for evidence of superficial and deep infection. There should be a dedicated pain team to ensure that education of staff occurs and to carry out regular audits of the service.

Analgesia, Epidural↗
PubMed2001

Technical challenges of hepatic venous outflow reconstruction in right lobe adult living donor liver transplantation.

A right lobe graft that is drained by the right hepatic vein (RHV) is obtained by transecting the liver on the right side of the middle hepatic vein (MHV). On occasion, a small RHV that only drains a portion of the right lobe, with the predominant outflow achieved by the MHV, is encountered. If such variation is not recognized while performing right lobe liver transplantation and the RHV only is used for reconstruction, venous outflow obstruction with subsequent graft congestion and eventual graft failure will occur. Additionally, preservation of the main MHV and its branch drainage of the left lobe is crucial to avoid outflow blockage to the remaining segment 4 in the donor. We report 4 cases showing a variant type of small RHV and large MHV branch that drain not only segments 5 and 8, but also segments 6 and 7. These variations were simultaneously associated with a large-caliber inferior RHV that also required reconstruction. The methods used to diagnose such anatomic variations and the techniques for reconstruction in the donor and recipient are described.

Adult↗
PubMed2001

Variation in Bordetella bronchiseptica flaA does not correlate with typing by macro-restriction analysis by pulsed-field gel electrophoresis.

A genotyping method based on PCR-RFLP analysis of the flagellin gene (flaA) was applied to 30 mainly feline isolates of Bordetella bronchiseptica. These isolates were separated into three PCR-RFLP groups with the restriction endonucleases HaeIII, MspI, MboI and RsaI. flaA nucleotide sequences representing each of the three groups differed from each other by 11-13%. One of the groups exhibited far greater flaA sequence identity with the cryptic flagellin gene sequence of B. pertussis (>97%) than with flaA sequences from representatives of the other B. bronchiseptica PCR-RFLP groups. Amongst the 30 isolates were at least 10 representing each of the two major genotypes (A and B) identified in a previous study by macro-restriction analysis and pulsed-field gel electrophoresis (PFGE), as well as representatives of other less common genotypes. Each of the major PFGE genotypes contained strains representing more than one flagellin genotype. Indeed, there was no correlation between the two molecular typing methods. PFGE analysis may identify differences due to genomic re-arrangements rather than genuine variations in gene content. If so, relationships inferred on the basis of PFGE or other molecular methods for whole genome comparison should be treated with caution.

Bacterial Typing Techniques↗
PubMed2001

Vocal behavior of male sperm whales: why do they click?

Off Kaikoura, New Zealand, we recorded individually identified male sperm whales (Physeter macrocephalus) for entire dive cycles in order to investigate vocal behavior of individual whales and to examine possible functions of sperm whale clicks. In our study, sperm whales were almost always silent at the surface. They consistently started clicking within 25 s after fluking-up and diving. During the first 10 s of clicking, interclick intervals were significantly correlated with water depths at the location of fluke-up. The first "creak" was produced on average 7.5 min into a dive. Interclick intervals usually decreased substantially before clicks turned into "creaks." The highest click rate recorded in this study was 90.9 click/s, and clicks-within-creaks were much shorter than "usual clicks" (mean of 3.6 ms versus 17 to 30 ms). The number of creaks per minute of dive and the length of a dive were significantly correlated. On average, sperm whales were silent for the last 3.6 min before surfacing. Short sequences of "surface clicks" (3 to 8 metallic clicks with mean interclick interval of 5.5 s) were often produced at the end of a dive (in 57% of the dives), but their function remains puzzling. The results of this study suggest that usual clicks and creaks are both used for echolocation purposes, the former to gather information about acoustically reflective features and the latter to detect prey.

Animals↗
PubMed2000

Evidence against a redshift z > 6 for the galaxy STIS123627+621755.

The identification of galaxies at extreme distances provides the most direct information about the earliest phases of galaxy formation. But at redshifts z > 5 even the most luminous galaxies appear faint; the interpretation of low signal-to-noise ratio data is difficult and misidentifications do occur. Here we report optical and near-infrared observations of the source STIS123627+621755, which was previously suggested to be at a redshift of 6.68 (ref. 1). At that redshift, and with the reported spectral energy distribution, the galaxy should be essentially invisible at wavelengths less than 9,300 A, because the intervening intergalactic medium absorbs almost all light energetic enough to ionize neutral hydrogen--that is, with wavelengths less than the redshifted Lyman limit of lambda = (1 + z) x 912A. At near-infrared wavelengths, however, the galaxy should be relatively bright. Here we report a detection of the galaxy at 6,700 A and a non-detection at a wavelength of 1.2 microm, contrary to expectations for z approximately 6.68. The data conservatively require that STIS123627+621755 has a redshift z < 6.

Journal Article↗
PubMed2000

Discovery of a Color-selected Quasar at z = 5.50.

We present observations of RD J030117+002025, a quasar at z=5.50 discovered from deep, multicolor, ground-based observations covering 74 arcmin2. This is the most distant quasar or active galaxy currently known. The object was targeted as an R-band dropout, with RAB>26.3 (3 sigma limit in a 3&arcsec; diameter region), IAB=23.8, and zAB=23.4. The Keck/Low-Resolution Imaging Spectrometer spectrum shows broad Lyalpha/N v lambda1240 emission and sharp absorption decrements from the highly redshifted hydrogen forests. The fractional continuum depression due to the Lyalpha forest is DA=0.90. RD J030117+002025 is the least luminous high-redshift quasar known (MB approximately -22.7).

Journal Article↗
PubMed2000

Detection of type III secretion system genes in animal isolates of Bordetella bronchiseptica.

A cosmid clone bank of Bordetella bronchiseptica genomic DNA was screened for the presence of type III secretion (TTS) genes using a probe derived from the TTS system genes of Ralstonia solanacearum. A 3.35kb PstI fragment, sub-cloned from a hybridising cosmid clone, was sequenced and found to contain a 97bp overlap with the previously reported B. bronchiseptica bscIJKLNO TTS gene cluster. DNA and predicted protein homology analysis suggests that a bscPQRST cluster lies immediately downstream of bscIJKLNO. A PCR amplification assay indicated that the bscT locus was present in 27 B. bronchiseptica animal isolates tested (100%). Dot-blot DNA hybridisation using probes for bscT and bscP confirmed the presence of these loci in six canine isolates associated with a variety of clinical signs. Although TTS has been implicated in the pathogenicity of B. bronchiseptica, it is likely that different clinical manifestations may be due to variations in gene expression or host factors, rather than the absence or presence of TTS genes.

Amino Acid Sequence↗
PubMed2000

Comparison of serological and sequence-based methods for typing feline calcivirus isolates from vaccine failures.

Feline calicivirus (FCV) can be typed by exploiting antigenic differences between isolates or, more recently, by the sequence analysis of a hypervariable region of the virus's capsid gene. These two methods were used to characterise FCV isolates from 20 vaccine failures which occurred after the use of a commercial, live-attenuated vaccine. Using virus neutralisation, the isolates showed a spectrum of relatedness to the vaccine; depending on the criterion adopted for identity, 10 to 40 per cent of them appeared to be similar to the vaccine virus. Using sequence analysis, the isolates fell into one of two categories; 20 per cent had a similar sequence to the vaccine (0-67 to 2-67 per cent distant), and the remainder had a dissimilar sequence (21-3 to 36-0 per cent distant). Sequence analysis identified one cat that appeared to be infected with two distinct FCVs. The serological and sequence-based typing methods gave the same result in 80 to 95 per cent of individual cases, depending on the criterion adopted for serological identity. It is suggested that molecular typing is a more definitive method for characterising the relatedness of FCV isolates.

Animals↗
PubMed2000

Relation between circadian patterns in levels of circulating lipoprotein(a), fibrinogen, platelets, and related lipid variables in men.

BACKGROUND: A correlation has been reported between lipoprotein(a) [Lp(a)] concentration and risk for coronary artery disease. High concentrations of Lp(a) might be markers for vascular or tissue injury or might be associated with other genetic or environmental factors that can cause acute myocardial infarction. METHODS: We measured the circadian characteristics of circulating Lp(a), fibrinogen, platelets, cholesterol, triglycerides, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol for a group of adult male volunteers who had no clinical symptoms. We obtained samples every 3 hours around the clock to assess the normal degree of variation within a 24-hour period and to test for similarities in circadian patterns and correlations with level of Lp(a). RESULTS: Each variable displayed a highly significant circadian rhythm. Lp(a), fibrinogen, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol peaked in the morning. Cholesterol and platelets peaked in the late afternoon, and triglycerides peaked in the evening. CONCLUSIONS: Although peak levels of Lp(a) and fibrinogen coincide with reported morning peak frequencies of myocardial infarction and stroke, the platelet peak appears to coincide with late afternoon peak frequencies of sudden cardiac death and fatal stroke. The data suggest that proper timing of single samples may improve the usefulness and accuracy of diagnosis, risk assessment, and therapy.

Aged↗