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Biomedical subjects

G O'Neill

Publications and source records attributed to G O'Neill.

At least 55 records · Page 3Linked to original sources
PubMed1994

Nasal airflow after septorhinoplasty.

The changes in nasal function which occur after septorhinoplasty for obstruction were investigated by anterior rhinomanometry in 15 subjects. Objective and subjective measures of outcome were compared. Anterior rhinomanometry was performed after nasal decongestion. These data were mathematically transformed to determine the amount of airflow asymmetry through the nostrils and the stiffness of the nasal valve. The results suggested that the presence of gross airflow asymmetry (> +/- 80%) in patients prior to surgery was a bad prognostic indicator for post-operative satisfaction with the airway. Patient satisfaction with function and cosmetic appearance post-operatively was correlated with the presence of symmetrical nasal airflow. Nasal valve stiffness did not seem to be affected by septorhinoplasty.

Adult↗
PubMed1994

Chronic occult intra-alveolar hemorrhage: a rare cause of failure to respond to erythropoietin.

Recombinant human erythropoietin (EPO) is an effective and safe therapy for correction of anemia in end-stage renal disease (ESRD). Clinical trials reported to date suggest that EPO improves anemia in over 90% of hemodialysis patients with anemia (Eschbach 1989). Factors which have been identified that appear to inhibit the effectiveness of EPO are infection [Muirhead N et al. 1990], iron deficiency, hyperparathyroidism, aluminium excess [Casati 1991] and persistent GIT bleeding. The development of reticulocytosis in response to EPO in the absence of a rise in hematocrit should alert the clinician to the possibility of either hemolysis or occult blood loss. We present a case in which, despite the development of a reticulocytosis of 5% in response to EPO and the absence of hemolysis, we had difficulty in identifying the presumed source of blood loss.

Anemia↗
PubMed1993

A molecular characterization of Clostridium difficile isolates from humans, animals and their environments.

It is generally accepted that most patients with Clostridium difficile-associated diarrhoea acquire the organism from the environment. Recently we demonstrated that household pets may constitute a significant reservoir of C. difficile through gastrointestinal carriage in up to 39% of cats and dogs. These findings suggested that direct transmission from household pets, or contamination of the environment by them, may be a factor in the pathogenesis of C. difficile-associated diarrhoea. To investigate this possibility, we examined isolates of C. difficile from humans, pets and the environment by restriction enzyme analysis (REA) and restriction fragment length polymorphism (RFLP) typing using enhanced chemiluminescence. Both REA and RFLP typing methods used Hind III digests of chromosomal DNA. A total of 116 isolates of C. difficile from pets (26), veterinary clinic environmental sites (33), humans (37) and hospital environmental sites (20) was examined. REA was far more discriminatory than RFLP typing and for all isolates there were 34 REA types versus 6 RFLP types. There was good correlation between the REA types found in isolates from pets and from the veterinary clinic environment, and between isolates from humans and from those found in the hospital environment. There was, however, no correlation between REA type of C. difficile found in pets and isolates of human origin. We conclude that there may still be a risk of humans acquiring C. difficile from domestic pets as these findings may be the result of geographical variation.

Animals↗
PubMed1988

A comparison between area and volume measurements of the mastoid air spaces in normal temporal bones.

In a study of 26 normal cadaveric temporal bones, a significant correlation was found between the area of the mastoid air spaces assessed from a conventional lateral radiograph and the mastoid volume as determined using high resolution computed tomography. The relationship, which was found to be linear, is of the form V = 0.82 A + 0.13. The correlation coefficient is 0.95 with a residual standard deviation about the regression of 1.14 cm3. It is apparent, therefore, that an accurate assessment of the mastoid air space volume can be obtained by means of a simple and routinely requested investigation, i.e. the 35 degree lateral oblique radiograph.

Humans↗
PubMed1988

Theoretical considerations of nasal airflow mechanics and surgical implications.

A mathematical model relating nasal airflow and pressure, using Bernoulli's equation applied to flow through the nasal valve region, has been shown to give values of resistance which correlate well with those measured experimentally. It is concluded that the nasal valve is the primary location for nasal resistance and that the nasal vault contributes a negligible amount to the total transnasal pressure drop. Flow limitation is predicted in the model by incorporation of a term describing nasal valve stiffness. The interrelationship of the alar wing and nasal valve are demonstrated and the model is discussed in terms of aiding the understanding of normal airflow physiology and what implications this may have for septal spur surgery.

Airway Resistance↗
PubMed1987

The influence of temporal bone anatomical variation upon the caloric stimulus.

This study involved a comparison of temperature changes occurring in isolated cadaveric temporal bones as a result of caloric stimulation, with information gained from radiological examination of the bones by means of high resolution computed tomographic scanning. This was performed in order to investigate the complex nature of heat transfer within the temporal bone and the influence which anatomical variations may have upon the accuracy of evaluation of vestibular function by means of the caloric test. No significant correlation could be found between the maximum temperature change occurring across the lateral semicircular canal and any of the parameters obtained from radiological assessment except for the diameter of the internal auditory meatus. It was deduced that an intra-subject difference in the diameters of the internal auditory meatus of 0.5 mm would introduce an absolute error in the evaluation of percentage canal paresis of 10%. Since normal intra-subject differences in internal meatus diameter can exceed 0.5 mm, this finding was considered to be highly significant.

Caloric Tests↗
PubMed1986

Structure of the gene encoding the exoglucanase of Cellulomonas fimi.

In Cellulomonas fimi the cex gene encodes an exoglucanase (Exg) involved in the degradation of cellulose. The gene now has been sequenced as part of a 2.58-kb fragment of C. fimi DNA. The cex coding region of 1452 bp (484 codons) was identified by comparison of the DNA sequence to the N-terminal amino acid (aa) sequence of the Exg purified from C. fimi. The Exg sequence is preceded by a putative signal peptide of 41 aa, a translational initiation codon, and a sequence resembling a ribosome-binding site five nucleotides (nt) before the initiation codon. The nt sequence immediately following the translational stop codon contains four inverted repeats, two of which overlap, and which can be arranged in stable secondary structures. The codon usage in C. fimi appears to be quite different from that of Escherichia coli. A dramatic (98.5%) bias occurs for G or C in the third position for the 35 codons utilized in the cex gene.

Amino Acid Sequence↗
PubMed1985

Ultrasound examination in the diagnosis of popliteal artery aneurysms.

Popliteal artery aneurysm is a potentially limb-threating lesion which is frequently difficult to diagnose by clinical examination or angiography. The risk of limb loss can best be reduced by early diagnosis. Over the past 5 years we have prospectively evaluated ultrasound examination of the popliteal space in screening patients with clinically suspected popliteal artery aneurysms. One hundred patients who were suspected clinically of having a popliteal artery aneurysm underwent bilateral ultrasound examination of their popliteal fossae. There were 21 patients who had abnormal scans. The problems identified were popliteal artery aneurysm in thirteen patients, popliteal artery ectasia in four patients, Baker's cyst in two patients, thrombosis in one patient and popliteal stenosis in one patient. Eight patients with eleven popliteal artery aneurysms by ultrasound also underwent angiography. Seven of the aneurysms were confirmed, four were missed. All eleven aneurysms were confirmed at operation. In addition, angiography did not demonstrate an aneurysm in any patient with a normal ultrasound. This study confirms that ultrasound examination is a quick, accurate, and non-invasive method of screening for popliteal artery aneurysms.

Adult↗
PubMed1985

Complement and HLA. Further definition of high-risk haplotypes in insulin-dependent diabetes.

The families of 41 probands with type I (insulin-dependent) diabetes mellitus (IDDM) were typed for HLA-A, HLA-B, and HLA-DR antigens in addition to the complement polymorphisms C2, C4A, C4B, and Bf. All of these loci are encoded on the short arm of human chromosome 6 in a narrow region. Alleles at HLA-B (8, 15, 18, and 40), HLA-DR (3 and 4), and Bf (F1) have been associated with increased relative risk (RR) for IDDM, while HLA-B7 and HLA-DR2 have been associated with decreased RR for IDDM. This study confirms those significant risks in addition to confirming increased risk for the null (silent) allele for C4A (C4AQ0) and a rare C4B variant (C4B2.9). The significantly associated antigens (alleles) and risks were: HLA-B8 (RR = 3.1), HLA-DR3 (RR = 5.2), HLA-DR4 (RR = 4.3), and BfF1 (RR = 7.1), in addition to C4AQ0 (RR = 2.8) and C4B2.9 (RR = 12.6). Significantly low risk was associated only with HLA-DR2 (RR = 0.1). In a recent study, we defined five high-risk haplotypes that were determined solely by HLA-B, Bf, and HLA-DR (B8-BfS-DR3, B8-BfS-DR4, B15-BfS-DR4, B18-BfF1-DR3, and B40-BfS-DR4). By inclusion of information from the complement polymorphism, we have defined in greater detail three of these five high-risk haplotypes. One previously identified haplotype (B40-BfS-DR4) showed no complement clustering, while the rare high-risk haplotype (B8-BfS-DR4) was seen only once in this smaller sample.(ABSTRACT TRUNCATED AT 250 WORDS)

Alleles↗
PubMed1985

Asymptomatic cavitary pneumonitis due to amiodarone pulmonary toxicity.

A 52-year-old woman presented with ventricular tachycardia after receiving amiodarone for the previous 18 months. The chest roentgenogram revealed evidence of multiple pleural-based cavitary nodules despite the absence of respiratory disease on clinical examination. The nodules were attributed to amiodarone because of histologic changes noted at open-lung biopsy. The cavitating nodules cleared with the discontinuation of amiodarone.

Journal Article↗
PubMed1982

Regulation of human lymphocyte activation by alpha-fetoprotein. Evidence for selective suppression of Ia-associated T-cell proliferation in vitro.

The immunoregulatory effects of purified human fetal- and hepatoma-derived AFP have been evaluated on allogeneic and autologous mixed lymphocyte reactions (AMLR). In striking contrast to the weak or negligible inhibitory effect on allogeneic reactions, the relatively vigorous proliferative activity of normal human T lymphocytes responding to irradiated autologous non-T stimulator cells was found to be highly sensitive to AFP-mediated suppression. Thus, the addition of purified AFP to AMLRs in concentrations that can be considered physiological with respect to the levels normally detected in fetal and newborn sera reduced the proliferative response by as much as 80 to 90 per cent of control responses occurring in the presence of equivalent amounts of albumin. Consistent immunosuppressive effects were observed in tests with six individually isolated preparations of AFP and no significant differences were evident in the inhibitory potency of fetal versus hepatoma AFP. AMLRs were also shown here to be more susceptible than allogeneic reactions to the blocking effect of anti-Ia antibodies. Therefore, on the basis of our present findings we suggest that an important, and perhaps primary function of AFP may be to control Ia-associated autoreactive T cell proliferation during early ontogeny. Consistent with this reasoning is our finding that most of the strong immunosuppressive action of cord serum on AMLR is abrogated by the selective removal of AFP.

Histocompatibility Antigens Class II↗
PubMed1981

Comparison between iodamide and iothalamate in intravenous urography.

A number of iodinated contrast media such as Iothalamate, whose excretion depends on glomerular filtration are well established for use in intravenous urography. Iodamide, a relatively new iodinated contrast medium, is thought to be actively secreted by the tubules in addition to glomerular filtration. We set out to compare the nephrogram and pyelogram using these two types of contrast medium, injecting each either slowly or rapidly. Only patients with normal plasma urea and creatinine concentrations were included in the assessment. The results, although inconclusive, suggest that the quality of the nephrogram and pyelogram is better with Iodamide than with Iothalamate.

Humans↗