Biomedical subjects

H O'Shea

Publications and source records attributed to H O'Shea.

11 recordsLinked to original sources

PubMed2006

Molecular characterisation and analysis of bovine rotavirus strains circulating in Ireland 2002-2004.

One hundred and two faecal samples were collected from calves diagnosed with rotavirus infection, in the southern region of Ireland, from 2002 to 2004. Ninety one percent (n=93) were confirmed positive for rotavirus, using latex agglutination and enzyme linked immunosorbent assay (ELISA) methods. Determination of the G- and P-types was carried out using nested reverse transcriptase polymerase chain reaction (nRT-PCR). G6 was the most prevalent genotype, accounting for 80.6% (75/93), G10 accounted for 6.5% (6/93) and G6G10 mixed types accounted for 9.7% (9/93) of the collection. Rotavirus in three of the samples (3.2%) could not be characterised with any of the five G-specific primers used in this study. A subset of the positive samples (n=54) was examined for their P-type specificities, P[5] and P[11] accounted for 77.8% (42/54), and 9.3% (5/54), respectively. One P[1] genotype (1.9%) was found in the collection. P[5] and P[11] mixed genotypes accounted for 11% (6/54) of the study. The genotypes corresponded to the UK-like strain (G6P[5]) 57.4%, KN4-like strain (G6[P11]) 7.4%, B223-like strain (G10P[11]) and NCDV-like strain (G6P[1]) 1.9% each. The unusual combination of G10P[5] accounted for 7.4%, with mixed infections G6+G10P[5] and G6P[5]+P[11] representing 13% and 11%, respectively. This is the first time that the G- and P-types of bovine rotaviruses (BRVs) have been determined in Ireland, and this study contributes to a better understanding of the epidemiology of such viruses circulating in Ireland.

Animals↗

PubMed2006

Effect of X- and Y-box deletions on the development of diabetes in H-2Ealpha-chain transgenic nonobese diabetic mice.

The development of type 1 diabetes in nonobese diabetic (NOD) mice is influenced by major histocompatibility complex (MHC) class II genes. The NOD-E transgenic mouse, which expresses H2-E as a result of the introduction of an Ead gene, is protected from development of type 1 diabetes. While the mechanism of protection remains unclear, the effect has been regarded as a model system for MHC protection from autoimmunity. We have investigated the effect of deletions of the Ea promoter region, which, in turn, affect H2-E expression patterns in transgenic NOD mice. We have constructed transgenic NOD mice where the X (DeltaX) and Y (DeltaY) boxes of the Ead gene have, respectively, been functionally deleted. Previous reports, using X- or Y-box-deleted H2-E transgenic mice, made by crossing the appropriate transgenes onto the NOD background from C57BL/6 transgenic mice, indicated that promoter mutation abrogated the H2-E-mediated protection seen in NOD-E. The NOD DeltaX and NOD DeltaY transgenic mice generated in the present study differ in susceptibility to diabetes from wild-type NOD mice. NOD DeltaY1 animals are protected from diabetes development, while DeltaX mice remain susceptible, albeit to a lesser extent than the parental NOD strain.

Animals↗

PubMed2004

Atomic force microscopy of BHK-21 cells: an investigation of cell fixation techniques.

The atomic force microscope (AFM) has been used to image a wide variety of biological samples, including cultured cells, in air. Whilst cultured cells have been prepared for AFM analysis using a variety of matrices and fixatives, a definitive study of sample preparation and its effects on cell morphology has not, as far as the authors are aware, previously been reported. Although a considerable number of cell fixatives exist, no single fixative is ideal for all investigations. Prior to the performance of specialised techniques, such as atomic force microscopy of cultured cells in air, the cell fixation method must be investigated and optimised. The fixative abilities of 2% paraformaldehyde-lysine-periodate, 0.25% glutaraldehyde, paraformaldehyde-glutaraldehyde, 4% phosphate-buffered formal saline, 1% formaldehyde, methanol:acetone, formal saline, 4% paraformaldehyde and ethanol:acetic acid were assessed in this study. A qualitative assessment system was used to evaluate the efficacy of the above fixatives using conventional fixation criteria (i.e. the presence of fibroblastic morphology consistent with optical microscopy and the absence of fixation artifacts). The optimal fixative was identified as 4% paraformaldehyde, which was capable of providing optically consistent images of BHK-21 (fibroblastic) cells, whose heights remained within the measurement capability of the AFM instrument used in this study.

Animals↗

PubMed2004

Atomic force microscopy analysis of enveloped and non-enveloped viral entry into, and egress from, cultured cells.

Since its invention, the atomic force microscope has been used to image a wide variety of biological samples, including viruses. Viral entry into, and egress from, cultured cells has been extensively studied using numerous scientific techniques and to a limited extent using atomic force microscopy. One of the main structural differences that can exist between viruses is the absence, or presence, of an envelope and this factor has consequences for the mode of viral entry and egress. In this study, the entry into, and egress from, cultured cells of enveloped and non-enveloped viruses were investigated using atomic force microscopy. No significant cell surface changes were observed following infection with enveloped or non-enveloped viruses. Although roughness analysis of viral entry revealed cell smoothing post-infection, no differences between the roughness values of enveloped and non-enveloped viral entry were observed. Line analysis of viral entry revealed minor differences between cells infected with an enveloped rather than a non-enveloped virus. These differences may represent a distinction between the uptake processes of enveloped and non-enveloped viruses. Studies of viral egress revealed that infected cells were undergoing cytopathic changes. Whilst topographic, height and roughness differences clearly occurred between virally- and mock-infected cells, no significant differences were elucidated between enveloped and non-enveloped viral egress.

Animals↗

PubMed2002

Immobilisation of Semliki forest virus for atomic force microscopy.

Semliki Forest virus (SFV), an alphavirus, is a single-stranded positive-sense RNA virus. The RNA genome is surrounded by a protein shell known as the capsid which itself is surrounded by a lipid envelope of host cell origin. In this study, SFV strain L10 enveloped virus and its capsid were immobilised onto silicon wafer supports which had been pre-coated with a monolayer of the relevant anti-viral antibody. After drying, the samples were imaged in air, using non-contact mode atomic force microscopy (AFM). Quantification of the AFM images has revealed that both the strain L10 enveloped virus and capsid collapse when immobilised in this manner. The capsid undergoes more significant collapse compared to the enveloped virus. The dimensions of the immobilised enveloped virus and capsid have been compared to a model where the free spherical particles collapse into ellipsoids during immobilisation. For the immobilised capsid the dimensions are consistent with this model whereas for the enveloped virus the model is less effective. The dimensions of the enveloped virus appear to be affected by the antibody used for immobilisation.

Animals↗

PubMed2001

Influence of nitrous oxide on induction of anaesthesia with sevoflurane.

Nitrous oxide is often used during inhalation induction of anaesthesia with sevoflurane. Although the value of using nitrous oxide during inhalation induction with other volatile anaesthetics has been studied, the popularity of sevoflurane induction and the different characteristics of this agent make a study of the combination of nitrous oxide with this agent of interest. We compared induction times, oxygenation, and excitatory events during inhalation induction of anaesthesia using sevoflurane, with and without nitrous oxide. We studied 64 female patients, randomly allocated to receive inhalation induction of anaesthesia using sevoflurane with or without 50% nitrous oxide in the fresh gas, using a co-axial breathing system (Mapleson D) and a fresh gas flow rate of 3-6 litre min(-1). Mean time to induction of anaesthesia (fall of an outstretched arm) was 102 s in both groups, but excitation (limb or head movement) was more frequent in those receiving nitrous oxide (10 patients) than in those receiving oxygen only (five patients) (P<0.05). Oxygenation was similar in both groups. We conclude that nitrous oxide confers no advantage when anaesthesia is induced with sevoflurane in this way.

Adolescent↗

PubMed2000

Bilateral optic atrophy following diabetic ketoacidosis.

Diabetic ketoacidosis (DKA) can result in neuropathic abnormalities of the somatic and the autonomous nervous systems. We report the case of a 50-year-old man with Type 1 diabetes of 20-year duration who after severe DKA lost vision in his right eye and only retain partial vision in his left. This case demonstrates that optic neural tissue is vulnerable to haemodynamic and metabolic complications of DKA.

Dehydration↗

PubMed2000

Molecular characterization of rotavirus in Ireland: detection of novel strains circulating in the population.

A collection of three hundred thirty rotavirus-positive stool samples from children with diarrhea in the southern and eastern regions of Ireland between 1997 and 1999 were submitted to the Molecular Diagnostics Unit of the Cork Institute of Technology, Cork, Ireland, for investigation. These strains were characterized by several methods, including polyacrylamide gel electropherotyping and G and P genotyping. A subset of the G types was confirmed by nucleic acid sequencing. The most prevalent types found in this collection included G1P[8] (n = 106; 32.1%), G2P[4] (n = 94; 28.5%), and G4P[8] (n = 37; 11.2%). Novel strains were also detected, including G1P[4] (n = 19; 5.8%), and G4P[4] (n = 2; 0.6%). Interestingly, mixed infections accounted for 18.8% (n = 62) of the total collection, with only 3% (n = 10) which were not G and/or P typeable. Significantly, six G8 and five G9 strains were identified as part of mixed infections. These strains have not previously been identified in Irish children, suggesting a greater diversity in rotavirus strains currently circulating in Ireland.

Child, Preschool↗

PubMed1999

Infection with Schistosoma mansoni prevents insulin dependent diabetes mellitus in non-obese diabetic mice.

The spontaneous development of insulin dependent diabetes mellitus in non-obese diabetic (NOD) mice has been shown to be mediated by a Th1 response against beta cell antigens. It is known that in murine models of Schistosoma mansoni infection, egg production is associated with a switch from a Th1 to Th2 response. This subsequent dominance of a Th2 response in S.mansoni infected mice has been shown to influence the response to other infectious agents or antigens. We therefore determined whether infection with S.mansoni could influence the spontaneous incidence of insulin dependent diabetes mellitus (IDDM) in NOD mice. Infection with this helminth significantly reduced the spontaneous incidence of IDDM. IDDM was also prevented by injecting parasite eggs alone. Because until relatively recently humans might expect to succumb to a variety of infectious agents, the current freedom from infection might permit the expression of a genetic predisposition to autoimmune pathology and be responsible for the increased incidence of IDDM.

Animals↗

PubMed1998

An efficient selection system for packaging herpes simplex virus amplicons.

Due to their simplicity and flexibility of genomic construction, herpes simplex virus (HSV) amplicon-based vectors are attractive vehicles for gene delivery. However, a significant problem faced in the generation of amplicon stocks is the low amplicon to helper virus (A/H) ratio. In order to improve the proportion of amplicons generated, a selection system for amplicon production was developed in which the HSV thymidine kinase (TK) gene is inserted into an amplicon plasmid and an HSV mutant with both TK and glycoprotein H (gH) genes deleted is used as a helper virus. Using a protocol in which amplicon stocks are passaged 2-3 times in BHK cells of TK- and gH+ genotype in the presence of selection medium containing methotrexate, stock preparations with high A/H ratio (up to 5:1) and high amplicon titre (>1 x 10(9) infectious units/ml) were generated. In vitro characterization demonstrated that a high level of biologically functional products can be efficiently produced from these amplicon constructs.

Animals↗

PubMed1997

The PI capsid region of Theiler's virus controls replication in mouse glial cell cultures.

The GDVII strain of Theiler's virus is virulent. The DA strain is avirulent and can persist and initiate lesions of inflammatory demyelination in the CNS of susceptible strains of mice. Other, resistant strains of mice clear the infection. Replication of the GDVII and DA strains of Theiler's virus and their genetic recombinants R2, R3 and R4 were compared in mixed glial cell cultures derived from the mouse CNS. Differences were observed in the early rate of viral production. These mapped to the P1 capsid region of the viral genome. Viruses with GDVII P1 sequences produced virus and spread more rapidly than viruses with DA P1 sequences. GDVII virus infected greater numbers of cells than DA virus. Both strains of virus rapidly replicated at least to the level of translation in astrocytes (GFAP+), macrophage/microglial cells (F4/80+), oligodendrocytes (O4+) and bipotential precursor (A2B5+) cells. Early in infection many A2B5+ and GFAP+ cells were infected and destroyed. In contrast, O4+ cells were relatively resistant to cell-death. The cultures survived and produced virus over 14 days of study, at which time all 4 cell-type were present in the culture but < 1% of all the cells, the majority of which were O4+, expressed viral protein. Most of these infected O4+ cells retained a healthy morphology with extensive sheets of cytoplasm, suggesting that Theiler's virus infection of mature oligodendrocytes was non-destructive.

Animals↗