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Biomedical subjects

S J O'Brien

Publications and source records attributed to S J O'Brien.

At least 127 records · Page 7Linked to original sources
PubMed1996

A canine distemper virus epidemic in Serengeti lions (Panthera leo).

Canine distemper virus (CDV) is thought to have caused several fatal epidemics in canids within the Serengeti-Mara ecosystem of East Africa, affecting silver-backed jackals (Canis mesomelas) and bat-eared foxes (Otocyon megalotis) in 1978 (ref. 1), and African wild dogs (Lycaon pictus) in 1991 (refs 2, 3). The large, closely monitored Serengeti lion population was not affected in these epidemics. However, an epidemic caused by a morbillivirus closely related to CDV emerged abruptly in the lion population of the Serengeti National Park, Tanzania, in early 1994, resulting in fatal neurological disease characterized by grand mal seizures and myoclonus; the lions that died had encephalitis and pneumonia. Here we report the identification of CDV from these lions, and the close phylogenetic relationship between CDV isolates from lions and domestic dogs. By August 1994, 85% of the Serengeti lion population had anti-CDV antibodies, and the epidemic spread north to lions in the Maasai Mara National reserve, Kenya, and uncounted hyaenas, bat-eared foxes, and leopards were also affected.

Amino Acid Sequence↗
PubMed1996

Molecular phylogeny of mitochondrial cytochrome b and 12S rRNA sequences in the Felidae: ocelot and domestic cat lineages.

Molecular phylogeny of the cat family Felidae is derived using two mitochondrial genes, cytochrome b and 12S rRNA. Phylogenetic methods of weighted maximum parsimony and minimum evolution estimated by neighbor-joining are employed to reconstruct topologies among 20 extant felid species. Sequence analyses of 363 bp of cytochrome b and 376 bp of the 12S rRNA genes yielded average pair-wise similarity values between felids ranging from 94 to 99% and from 85 to 99%, respectively. Phylogenetic reconstruction supports more recent, intralineage associations but fails to completely resolve interlineage relationships. Both genes produce a monophyletic group of Felis species but vary in the placement of the pallas cat. The ocelot lineage represents an early divergence within the Felidae, with strong associations between ocelot and margay, Geoffroy's cat and kodkod, and pampas cat and tigrina. Implications of the relative recency of felid evolution, presence of ancestral polymorphisms, and influence of outgroups in placement of the topological root are discussed.

Amino Acid Sequence↗
PubMed1996

How long is too long? Determining the early management of meningococcal disease in Birmingham.

OBJECTIVE: To determine the length of time cases of meningococcal disease wait before receiving parenteral antibiotic therapy in hospital. METHOD: The hospital case notes of residents of Birmingham who were admitted to local hospitals in 1993 and discharged with a diagnosis of meningitis or meningococcal disease were reviewed. This information was combined with that held by the West Midlands Ambulance Service. RESULTS: Forty out of the 82 patients (49%) who met the case definition had meningococcal infection. Twenty one patients (26%) were admitted by ambulance, 11 of whom had meningococcal infection. The mean time from a request for an ambulance to the patient reaching hospital was 52 min for those with meningococcal infection compared to 55 min for those without. Nineteen patients (47.5%) with meningococcal infection waited more than one hour after admission for antibiotic treatment. Seven had an initial diagnosis of meningitis or meningococcal infection. Ten out of 27 patients with a meningococcal rash (37%), 13 out of 22 patients aged under five years (59%) and 13 out of 24 patients with microbiologically confirmed meningococcal infection (54%) waited more than one hour for treatment. Seven patients with meningococcal infection received benzyl penicillin before admission. Six received hospital antibiotic treatment within the hour. CONCLUSION: The assumption that patients suspected of having meningitis or meningococcal disease are treated promptly once in hospital is not always correct. The results of this study reinforce the need for all doctors to give benzyl penicillin promptly to patients they suspect have meningococcal disease.

Anti-Bacterial Agents↗
PubMed1996

Influence of combinations of human major histocompatibility complex genes on the course of HIV-1 infection.

Major histocompatibility complex (MHC) genes (HLA in humans) regulate the immune response to foreign antigens. Molecular and serologic techniques were used to identify products of HLA class I, class II and transporter (TAP) genes (also part of the MHC) in homosexual seroconverters to human immunodeficiency virus type 1 (HIV-1). Comprehensive statistical analysis produced an HLA profile that predicted time from HIV-1 infection to the onset of AIDS. The profile was developed in a cohort of 139 men and evaluated in a second unrelated cohort of 102 men. In the evaluation cohort, the profile discriminated a sixfold difference between groups with the shortest and longest times to AIDS (P = 0.001). These findings support current theory about control of antigen processing by HLA genes and have implications for immunopathogenesis of HIV-1 and other infections.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Chiari I malformation and spinal cord injury: cause for concern in contact athletes?

We present a case of transient quadriparesis in an 8-yr-old football player with a normal cervical spinal canal but Chiari I malformation of the hindbrain. Chiari I consists of herniation of the cerebellar tonsils through the foramen magnum, which reduces space available for the spinal cord. Magnetic resonance imaging (MRI) of the brain or cervical spine can identify asymptomatic Chiari I, whereas previously myelography was necessary. The incidence and natural history of Chiari I malformation is reviewed, with special reference to the question of return-to-play in young athletes.

Arnold-Chiari Malformation↗
PubMed1996

Prevalence of antibodies to feline parvovirus, calicivirus, herpesvirus, coronavirus, and immunodeficiency virus and of feline leukemia virus antigen and the interrelationship of these viral infections in free-ranging lions in east Africa.

While viral infections and their impact are well studied in domestic cats, only limited information is available on their occurrence in free-ranging lions. The goals of the present study were (i) to investigate the prevalence of antibodies to feline calicivirus (FCV), herpesvirus (FHV), coronavirus (FCoV), parvovirus (FPV), and immunodeficiency virus (FIV) and of feline leukemia virus (FeLV) antigen in 311 serum samples collected between 1984 and 1991 from lions inhabiting Tanzania's national parks and (ii) to evaluate the possible biological importance and the interrelationship of these viral infections. Antibodies to FCV, never reported previously in free-ranging lions, were detected in 70% of the sera. In addition, a much higher prevalence of antibodies to FCoV (57%) was found than was previously reported in Etosha National Park and Kruger National Park. Titers ranged from 25 to 400. FeLV antigen was not detectable in any of the serum samples. FCoV, FCV, FHV, and FIV were endemic in the Serengeti, while a transient elevation of FPV titers pointed to an outbreak of FPV infection between 1985 and 1987. Antibody titers to FPV and FCV were highly prevalent in the Serengeti (FPV, 75%; FCV, 67%) but not in Ngorongoro Crater (FPV, 27%; FCV, 2%). These differences could be explained by the different habitats and biological histories of the two populations and by the well-documented absence of immigration of lions from the Serengeti plains into Ngorongoro Crater after 1965. These observations indicate that, although the pathological potential of these viral infections seemed not to be very high in free-ranging lions, relocation of seropositive animals by humans to seronegative lion populations must be considered very carefully.

Africa, Eastern↗
PubMed1996

Genetic and phylogenetic divergence of feline immunodeficiency virus in the puma (Puma concolor).

Feline immunodeficiency virus (FIV) is a lentivirus which causes an AIDS-like disease in domestic cats (Felis catus). A number of other felid species, including the puma (Puma concolor), carry a virus closely related to domestic cat FIV. Serological testing revealed the presence of antibodies to FIV in 22% of 434 samples from throughout the geographic range of the puma. FIV-Pco pol gene sequences isolated from pumas revealed extensive sequence diversity, greater than has been documented in the domestic cat. The puma sequences formed two highly divergent groups, analogous to the clades which have been defined for domestic cat and lion (Panthera leo) FIV. The puma clade A was made up of samples from Florida and California, whereas clade B consisted of samples from other parts of North America, Central America, and Brazil. The difference between these two groups was as great as that reported among three lion FIV clades. Within puma clades, sequence variation is large, comparable to between-clade differences seen for domestic cat clades, allowing recognition of 15 phylogenetic lineages (subclades) among puma FIV-Pco. Large sequence divergence among isolates, nearly complete species monophyly, and widespread geographic distribution suggest that FIV-Pco has evolved within the puma species for a long period. The sequence data provided evidence for vertical transmission of FIV-Pco from mothers to their kittens, for coinfection of individuals by two different viral strains, and for cross-species transmission of FIV from a domestic cat to a puma. These factors may all be important for understanding the epidemiology and natural history of FIV in the puma.

Amino Acid Sequence↗
PubMed1996

Labral injuries: accuracy of detection with unenhanced MR imaging of the shoulder.

PURPOSE: To prospectively assess the accuracy of unenhanced magnetic resonance (MR) imaging in the detection and localization of labral injuries. MATERIALS AND METHODS: One hundred three patients with clinically suspected shoulder injuries were prospectively examined with unenhanced MR imaging. A combination of gradient-echo and high-resolution fast-spin-echo axial pulse sequences were used. Surgical correlation was obtained in all patients. RESULTS: At surgery, 37 torn anterior, 36 torn superior, and 19 torn posterior labral were identified. The sensitivity for detection of these tears with MR imaging was 100%, 86%, and 74%, respectively; the specificity was 95%, 100%, and 95%, respectively. Overall, unenhanced MR imaging was 95% accurate in the detection of labral injuries. CONCLUSION: With appropriate pulse sequences, unenhanced MR imaging of the shoulder is an accurate technique for the detection and localization of labral injuries.

Adult↗
PubMed1995

Hypervariable genomic variation to reconstruct the natural history of populations: lessons from the big cats.

The extent and nature of variation in hypervariable regions DNA have been used in the past as a means to infer the natural histories of populations. We review the interpretation of the extent of genetic diversity for minisatellite DNA in the cheetah to estimate the timing of a population bottleneck in the species and the potential application of a second class of hypervariable DNA, microsatellite DNA, as a molecular tool to examine the natural histories of felid populations. A calibration curve relating the degree of allele fragment sharing in individuals to relatedness in a captive pedigree of cheetahs is presented. This measurement has important applications for management of potential matings in captive management situations.

Acinonyx↗
PubMed1995

African horse sickness and African carnivores.

African horse sickness (AHS) is a disease that affects equids, and is principally transmitted by Culicoides spp. that are biological vectors of AHS viruses (AHSV). The repeated spread of AHSV from sub-Saharan Africa to the Middle East, northern Africa and the Iberian peninsula indicate that a better understanding of AHS epizootiology is needed. African horse sickness has long been known to infect and cause mortality among domestic dogs that ingest virus contaminated meat, but it is uncertain what role carnivores play in transmission of the virus. We present evidence of widespread natural AHS infection among a diversity of African carnivore species. We hypothesize that such infection resulted from ingestion of meat and organs from AHS-infected prey species. The effect of AHS on the carnivores is unknown, as is their role in the maintenance cycle of the disease.

Africa↗
PubMed1995

Coadaptation and immunodeficiency virus: lessons from the Felidae.

The emergence of pathogenic viruses in new species offers an unusual opportunity to monitor the coadaptation of viruses and their hosts in a dynamic ongoing process of intense biological selection. Tracking lentivirus epidemics in man, monkeys and cats reveals genomic struggles at three levels: quasispecies divergence within an individual; coadaptation of virus and host genomes subsequent to disease outbreaks; and transmission, spread and pathogenesis in related host species. Aspects of each level are revealed by examining the genetic diversity of feline immunodeficiency virus in domestic and wild cat species. This approach has been facilitated by the recent genetic characterization of a novel lentivirus in lions.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Sporadic isolates of Escherichia coli O157.H7 investigated by pyrolysis mass spectrometry.

Thirty-six encoded isolates of Escherichia coli. 32 of which were of serotype O157, were examined by pyrolysis mass spectrometry (PyMS). Thirty-one of the serotype O157 isolates possessed the flagellar antigen H7 and produced Verocytotoxin (VT), the other isolate serotyped as H45 and was non-toxigenic. Eighteen of the VT-producing E. coli (VTEC) isolates were from sporadic disease in residents of the Northern Region. Standard principal component (PC) and canonical variate (CV) analysis of the data distinguished only the four non-O157 isolates from the remainder which were indistinguishable by this approach. A similarity matrix based on differences between individual CV means distinguished a further ten isolates. The matrix correctly clustered 2 pairs of isolates from siblings and 4 isolates from an affected family. A further 5 clusters of 3 or more isolates and 6 pairs of isolates were defined. These groupings proved to be homogenous for toxin phenotype but occasionally entrained isolates of dissimilar phage type. However, in general, PyMS-derived clustering of apparently sporadic isolates accorded with geographical locations as determined by postcode. PyMS, which is a quick and high volume capacity phenotypic technique, may be a useful addition to existing methods in the investigation of the epidemiology of sporadic VTEC disease.

Escherichia coli↗
PubMed1995

Molecular evolution of mitochondrial 12S RNA and cytochrome b sequences in the pantherine lineage of Felidae.

DNA sequence comparisons of two mitochondrial DNA genes were used to infer phylogenetic relationships among 17 Felidae species, notably 15 in the previously described pantherine lineage. The polymerase chain reaction (PCR) was used to generate sequences of 358 base pairs of the mitochondrial 12S RNA gene and 289 base pairs of the cytochrome b protein coding gene. DNA sequences were compared within and between 17 felid and five nonfelid carnivore species. Evolutionary trees were constructed using phenetic, cladistic, and maximum likelihood algorithms. The combined results suggested several phylogenetic relationships including (1) the recognition of a recently evolved monophyletic genus Panthera consisting of Panthera leo, P. pardus, P. onca, P. uncia, P. tigris, and Neofelis nebulosa; (2) the recent common ancestry of Acinonyx jubatus, the African cheetah, and Puma concolor, the American puma; and (3) two golden cat species, Profelis temmincki and Profelis aurata, are not sister species, and the latter is strongly associated with Caracal caracal. These data add to the growing database of vertebrate mtDNA sequences and, given the relatively recent divergence among the felids represented here (1-10 Myr), allow 12S and cytochrome b sequence evolution to be addressed over a time scale different from those addressed in most work on vertebrate mtDNA.

Acinonyx↗
PubMed1995

Lateral epicondylitis: correlation of MR imaging, surgical, and histopathologic findings.

PURPOSE: To determine the value of magnetic resonance (MR) imaging in the clinical management of chronic refractory lateral epicondylitis. MATERIALS AND METHODS: Coronal three-dimensional Fourier transform, multiplanar gradient-recalled-echo, and fat-suppressed sagittal images were obtained in 33 patients. Twenty of these patients underwent surgical débridement and/or primary tendon repair and were included in the correlative study. Surgical and pathologic reports were reviewed to determine the location and gross characteristics of the tissue. RESULTS: Findings at MR imaging correlated with the surgical findings of primary degeneration of the extensor carpi radialis brevis (n = 20). Histopathologic examination demonstrated neovascularization, disruption of collagen, and mucoid degeneration without inflammation. CONCLUSION: The use of MR imaging in patients with recalcitrant lateral epicondylitis assists in surgical planning. The definition of tendon degeneration and degree of tear, as depicted on MR images, correlate well with surgical and histologic findings.

Adult↗