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Biomedical subjects

A Elliot

Publications and source records attributed to A Elliot.

16 recordsLinked to original sources
PubMed2006

Scientific lessons from the first influenza pandemic of the 20th century.

Re-analysis of the influenza pandemic of 1918 has given reassurance about a rather low reproductive number (R(o)), a prolonged herald wave of virus and that the skewed mortality towards the young adult could be a singularly unique event dependent upon previous infection history, perhaps not to be repeated in a future pandemic. Over 99% of those who contracted the virus survived, in spite of the absence of antivirals, vaccine and antibiotics for the secondary bacteria infections which probably accounted for one-third of the 50 million deaths. Therefore, in spite of a three-fold population increase since 1918 and 100 thousand plane journeys daily, judicious and careful planning together with a stockpile of antiviral drugs, oseltamivir, zanamivir and M2 blockers and a generic H5N1 vaccine, and application of hygiene would be expected to reduce mortality in a new pandemic, to figures significantly less than 1918.

Disease Outbreaks↗
PubMed2005

A hypothesis: the conjunction of soldiers, gas, pigs, ducks, geese and horses in northern France during the Great War provided the conditions for the emergence of the "Spanish" influenza pandemic of 1918-1919.

The Great Influenza Pandemic of 1918-1919 was a cataclysmic outbreak of infection wherein over 50 million people died worldwide within 18 months. The question of the origin is important because most influenza surveillance at present is focussed on S.E. Asia. Two later pandemic viruses in 1957 and 1968 arose in this region. However we present evidence that early outbreaks of a new disease with rapid onset and spreadability, high mortality in young soldiers in the British base camp at Etaples in Northern France in the winter of 1917 is, at least to date, the most likely focus of origin of the pandemic. Pathologists working at Etaples and Aldershot barracks later agreed that these early outbreaks in army camps were the same disease as the infection wave of influenza in 1918. The Etaples camp had the necessary mixture of factors for emergence of pandemic influenza including overcrowding (with 100,000 soldiers daily changing), live pigs, and nearby live geese, duck and chicken markets, horses and an additional factor 24 gases (some of them mutagenic) used in large 100 ton quantities to contaminate soldiers and the landscape. The final trigger for the ensuing pandemic was the return of millions of soldiers to their homelands around the entire world in the autumn of 1918.

Animals↗
PubMed2004

The structure and receptor binding properties of the 1918 influenza hemagglutinin.

The 1918 influenza pandemic resulted in about 20 million deaths. This enormous impact, coupled with renewed interest in emerging infections, makes characterization of the virus involved a priority. Receptor binding, the initial event in virus infection, is a major determinant of virus transmissibility that, for influenza viruses, is mediated by the hemagglutinin (HA) membrane glycoprotein. We have determined the crystal structures of the HA from the 1918 virus and two closely related HAs in complex with receptor analogs. They explain how the 1918 HA, while retaining receptor binding site amino acids characteristic of an avian precursor HA, is able to bind human receptors and how, as a consequence, the virus was able to spread in the human population.

Amino Acid Sequence↗
PubMed2003

Cryptosporidium muris infection in bilbies (Macrotis lagotis).

Cryptosporidiosis is an enteric disease of animals and humans that can be fatal in immunocompromised individuals. There is no known effective treatment for cryptosporidiosis. Bilbies are threatened marsupials and are bred in captivity as part of a recovery program to re-introduce this species to the southwest of Western Australia. Cryptosporidium muris infection was detected in the faeces of bilbies at a captive breeding colony. Stress associated with a high density of bilbies in enclosures may have predisposed some of the bilbies to infection with C. muris. C. muris has been described in mice and was found in the faeces of one mouse trapped in the breeding enclosures. It is likely the bilbies acquired the infection from mice by faecal contamination of food and water. The infection cleared within 2 months from some bilbies, however others remained infected for 6 months and treatment was attempted with dimetridazole. Subsequently the parasite was no longer be detectable in the faeces.

Animals↗
PubMed2001

Prevalence of obstructive lung diseases and respiratory symptoms in relation to living environment and socio-economic group.

We wanted to test whether living environment, occupation and social position are risk factors for asthma and chronic bronchitis/emphysema (CBE). The prevalence of bronchial asthma, CBE, respiratory symptoms and smoking habits in a random sample of 12,071 adults aged 20-59 years was assessed in a postal survey with a slightly modified questionnaire previously used in central and northern Sweden (The OLIN studies). Occupation was coded according to a socio-economic classification system. Six different living environment areas were defined; city-countryside, seaside-not seaside and living close to heavy traffic-not living close to heavy traffic. Multiple logistic regression analysis (forward conditional) was applied to estimate the association between the proposed set of risk factors and self-reported obstructive lung diseases and lower respiratory symptoms controlling for age, gender and smoking. After two reminders, the response rate was 70.1% (n=8469); 33.8% of the responders were smokers. In all, 469 subjects (5.5%) stated that they had asthma and 4.6% reported CBE. Besides smoking, which was a risk for both asthma and CBE, there were different risk patterns for self-reported asthma and CBE. In the economically active population there was a tendency that CBE was more common among 'unskilled and semi-skilled workers'. This fact was further emphasized when the population was merged into the two groups 'low social position' and 'middle/high social position', with 'low social position' as a risk for CBE (OR=1.35, 95% CI=1.06-1.72). No social risk factors were identified for asthma. Living close to heavy traffic was a risk factor for asthma (OR=1.29, 95% CI=1.02-1.62) but not for CBE. Apart from this no living environmental risk factors for obstructive pulmonary diseases were identified. Asthma symptoms and long-standing cough were more common among those subjects living close to heavy traffic compared to those not living close to heavy traffic. To conclude, low social position was a risk factor for CBE and living close to heavy traffic was a risk factor for asthma.

Adult↗
PubMed2000

Molecular and phylogenetic analysis of Cryptosporidium muris from various hosts.

Isolates of Cryptosporidium muris and C. serpentis were characterized from different hosts using nucleotide sequence analysis of the rDNA 18S and ITS1 regions, and the heat-shock (HSP-70) gene. Phylogenetic analysis confirmed preliminary evidence that C. muris is not a uniform species. Two distinct genotypes were identified within C. muris; (1) C. muris genotype A; comprising bovine and camel isolates of C. muris from different geographical locations, and (2) C. muris genotype B comprising C. muris isolates from mice, a hamster, a rock hyrax and a camel from the same enclosure. These 2 genotypes may represent separate species but further biological and molecular studies are required for confirmation.

Animals↗
PubMed2000

Cryptosporidium meleagridis in an Indian ring-necked parrot (Psittacula krameri).

OBJECTIVE: To perform a morphological and genetic characterisation of a Cryptosporidium infection in an Indian ring-necked parrot (Psittacula krameri) and to compare this with C meleagridis from a turkey. DESIGN: Tissue and intestinal sections from an Indian ring-necked parrot were examined microscopically for Cryptosporidium. The organism was also purified from the crop and intestine, the DNA extracted and a portion of the 18S rDNA gene amplified, sequenced and compared with sequence and biological information obtained for C meleagridis from a turkey as well as sequence information for other species of Cryptosporidium. RESULTS: Morphological examination of tissue sections from an Indian ring-necked parrot revealed large numbers of Cryptosporidium oocysts attached to the apical border of enterocytes lining the intestinal tract. Purified Cryptosporidium oocysts measured about 5.1 x 4.5 microns, which conformed morphologically to C meleagridis. The sequence obtained from this isolate was identical to sequence information obtained from a C meleagridis isolate from a turkey. CONCLUSION: Cryptosporidium meleagridis was detected in an Indian ring-necked parrot using morphological and molecular methods. This is the first time that this species of Cryptosporidium has been reported in a non-galliform host and extends the known host range of C meleagridis.

Animals↗
PubMed1999

Sequence and PCR-RFLP analysis of the internal transcribed spacers of the rDNA repeat unit in isolates of Cryptosporidium from different hosts.

The Cryptosporidium ITS1, 5.8S and ITS2 rDNA regions from a number of Cryptosporidium isolates from different hosts and geographical areas were cloned and sequenced in order to investigate the extent of sequence heterogeneity between human and cattle-derived isolates from different geographical locations and also between isolates of Cryptosporidium from different hosts such as cats, pigs, mice and a koala. Calf-derived isolates from different continents were virtually identical as were human-derived isolates from the UK and Australia. Genetic differences between Cryptosporidium isolates were extensive and were in fact greater than the level of nucleotide divergence between Toxoplasma gondii and Neospora caninum rDNA sequences. Based on the sequence information derived from this study, PCR-RFLP of the ITS1 region was undertaken in order to directly amplify and genotype Cryptosporidium isolates from different hosts. This PCR-RFLP approach can now be used for molecular epidemiology studies, circumventing the need for costly sequencing and allowing a wider range of genetically different isolates to be examined.

Animals↗
PubMed1999

Molecular and biological characterisation of Cryptosporidium in pigs.

OBJECTIVE: Genetic and biological characterisation of 12 isolates of Cryptosporidium from pigs and comparing them with Cryptosporidium isolates from humans and cattle. DESIGN: Cryptosporidium isolates from pigs were compared with those obtained from human and cattle using rDNA sequence analysis. The infectivity of two of the porcine isolates was determined in neonatal mice and the clinical history of the infected pigs recorded. RESULTS: Pig-derived isolates of Cryptosporidium exhibited two distinct genotypes; a porcine genotype and a bovine genotype, which is common to cattle and other livestock. The porcine genotype did not produce any infection in neonatal mice whereas the bovine genotype did. CONCLUSION: Two distinct genetically and biologically differing strains of Cryptosporidium appeared to be associated with acute diarrhoea in pigs. Whether Cryptosporidium was a primary or secondary pathogen is unclear but warrants further investigation. As the bovine genotype is known to infect humans, the results suggest that pigs can act as reservoirs of cryptosporidial infections for humans and other live-stock. The zoonotic potential of the pig-adapted genotype is uncertain and requires further study.

Animals↗
PubMed1998

Morphological and genetic characterisation of Cryptosporidium oocysts from domestic cats.

Faecal samples were collected from domestic cats in the metropolitan area of the city of Perth, Western Australia, and screened for the presence of Cryptosporidium by both microscopy and PCR. Of 162 samples screened, two were positive for Cryptosporidium (a prevalence of 1.2%). Sample Ct33 was from an 18-month-old female and sample Ct131 from a 12-month-old female. Morphological studies revealed oocysts with an average size of 4.6 x 4.0 microm, smaller in size than isolates typically seen in humans (5.0 x 4.5 microm). Sequence analysis of PCR products showed sequences from cat isolates to be different to previously sequenced human and calf isolates, with cat isolates exhibiting 8.1% sequence divergence from these isolates. Phylogenetic analysis grouped the cat isolates into a distinct group, separate from other C. parvum isolates and Cryptosporidium species. These results lend support to the existence of a cat-adapted Cryptosporidium strain or species.

Animals↗
PubMed1998

Molecular characterization of Cryptosporidium from various hosts.

A 298 bp region of the Cryptosporidium parvum 18S rDNA and a 390 bp region of the acetyl-CoA synthetase gene were sequenced for a range of human and animal isolates of Cryptosporidium from different geographical areas. A distinct genotype is common to isolates from cattle, sheep and goats and also an alpaca from Peru and is referred to here as the 'calf'-derived Cryptosporidium genotype. Another genotype of 'human'-derived isolates also appears to be conserved amongst human isolates although humans are also susceptible to infection with the 'calf' Cryptosporidium genotype. Mice and pigs carry genetically distinct genotypes of Cryptosporidium. Three snake isolates were also analysed, 2 of which exhibited C. muris genotypes and the third snake isolate carried a distinct 'mouse' genotype.

Acetate-CoA Ligase↗
PubMed1989

The prognosis of tunnel preparations in treatment of class III furcations. A follow-up study.

The present study evaluated the long-term prognosis of tunnel preparations performed in a large number of teeth with advanced periodontal furcation defects. One hundred seven (107) patients, in which 156 teeth had been treated by tunnel preparations, were recalled for an evaluation, which was based on a questionnaire, a clinical examination, and radiographs; 102 patients attended (149 teeth = 95%). The mean observation time per tooth was 37.5 months (range 10 to 107 months). The results showed that 10 teeth (6.7%) had been extracted and 7 teeth (4.7%) hemisected. The indication for 12 of these extractions or hemisections was root caries. Among the remaining 132 teeth, 23 (15.4%) showed initial or established caries. There was no relationship between caries development and length of the observation time. Thus, approximately 75% of the teeth were still caries-free and in function. The findings demonstrated that tunnel preparations have a considerably better prognosis than previously reported and should be considered a valid treatment alternative.

Adult↗
PubMedDate not supplied

Aneurysm of the inferior vena cava: case report.

Venous aneurysms are uncommon. Despite their infrequency, venous aneurysms can present with significant clinical complications such as thrombosis, pulmonary embolism, and death. In this report, we present the case of a thrombosed inferior vena cava aneurysm discovered in a 16-year-old male who had deep vein thrombosis of the right lower extremity. Thrombosis of the inferior vena cava is uncommon in the pediatric population. Therefore, congenital abnormalities such as an inferior vena cava aneurysm should be considered when evaluating pediatric patients who present with deep vein thrombosis.

Adolescent↗
PubMedDate not supplied

X-ray surface dose measurements using TLD extrapolation.

Surface dose measurements in therapeutic x-ray beams are of importance in determining the dose to the skin of patients undergoing radiotherapy. Measurements were performed in the 6-MV beam of a medical linear accelerator with LiF thermoluminescence dosimeters (TLD) using a solid water phantom. TLD chips (surface area 3.17 x 3.17 cm2) of three different thicknesses (0.230, 0.099, and 0.038 g/cm2) were used to extrapolate dose readings to an infinitesimally thin layer of LiF. This surface dose was measured for field sizes ranging from 1 x 1 cm2 to 40 x 40 cm2. The surface dose relative to maximum dose was found to be 10.0% for a field size of 5 x 5 cm2, 16.3% for 10 x 10 cm2, and 26.9% for 20 x 20 cm2. Using a 6-mm Perspex block tray in the beam increased the surface dose in these fields to 10.7%, 17.7%, and 34.2% respectively. Due to the small size of the TLD chips, TLD extrapolation is applicable also for intracavity and exit dose determinations. The technique used for in vivo dosimetry could provide clinicians information about the build up of dose up to 1-mm depth in addition to an extrapolated surface dose measurement.

Electrons↗