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Biomedical subjects

J O'Riordan

Publications and source records attributed to J O'Riordan.

At least 19 recordsLinked to original sources
PubMed2005

Cross-calibration of dual-energy X-ray densitometers for a large, multi-center genetic study of osteoporosis.

Osteoporosis is a common disease with a strong genetic component characterized by reduced bone mass and an increased risk of fragility fractures. Bone mineral density (BMD) is the most important determinant of osteoporotic fracture risk, but the genes responsible for BMD regulation and fracture are incompletely defined. To enable multi-center studies to examine the genetic influences on BMD there is a requirement to standardize measurements across different manufacturers of bone densitometers, different versions of machines and different normative ranges. This paper describes a method developed to allow near-identical subjects with low age-adjusted BMD (based on Z-scores) to be recruited in 17 centers using 27 different densitometers. Cross-calibration was based on measurements using a European spine phantom circulated to all centers and measured ten times on each individual machine. From theses values an individual exponential curve, based on nominal versus observed BMD, was derived for each machine. As expected, there were large and significant variations in nominal BMD values, not only between scanners from different manufacturers but also between different versions of scanners from the same manufacturer. Hologic scanners tended to underestimate the nominal BMD, while Lunar scanners overestimated the value. Norland scanners gave mixed values over estimating BMD at the lower nominal value (0.5 g/cm2) while underestimating the value at the higher value (1.5 g/cm2). The validity of the exponential equations was tested using hip and spine measurements on 991 non-proband women from a familial osteoporosis study (FAMOS). After cross-calibration there was a considerable reduction in variation between machines. This observation, coupled with the absence of a similar reduction in variation attributable to a linear regression on age, demonstrated the validity of the cross-calibration approach. Use of the cross-calibration curves along with a standard normative range (in the case of this study, the Hologic normative range) allowed age-specific Z-scores to be used as an inclusion criterion in this genetic study, a method that will be useful for other trials where age-specific BMD inclusion criteria are required.

Absorptiometry, Photon↗
PubMed2005

A randomized comparison of the MCRI On-X and CarboMedics Top Hat bileaflet mechanical replacement aortic valves: early postoperative hemodynamic function and clinical events.

OBJECTIVE: This study compared hemodynamic function and clinical events in consecutive patients randomly assigned to receive a wholly supra-annular replacement valve or a valve with an intra-annular component. METHODS: Fifty-two patients with an average age of 62 years (range 40-74 years) were sized for both a CarboMedics Top Hat valve (CarboMedics Inc, Austin, Tex) and an MCRI On-X valve (Medical Carbon Research Institute, LLC, Austin, Tex) before random assignment to receive either valve type. Echocardiographic and clinical assessments were performed in the immediate postoperative period and at 1 year. RESULTS: The mean effective orifice areas were 1.41 +/- 0.42 cm2 for the Top Hat and 2.17 +/- 0.78 cm2 for the On-X (P < .0001). The mean pressure differences were 12.2 +/- 4.4 mm Hg and 6.9 +/- 3.6 mm Hg, respectively (P < .0001). New York Heart Association functional class was better with the On-X than the Top Hat valves, but there were no differences in clinical events, regression of left ventricular mass, or measures of hemolysis. CONCLUSION: The partially intra-annular MCRI On-X valve was hemodynamically superior to the wholly supra-annular CarboMedics Top Hat valve. However, there were no differences in early clinical outcomes between the two valve types.

Adult↗
PubMed2004

A single-centre assessment of long-term quality-of-life status after sibling allogeneic stem cell transplantation for chronic myeloid leukaemia in first chronic phase.

A total of 75 patients underwent sibling allogeneic stem cell transplantation (SCT) for chronic myeloid leukaemia in first chronic phase from 1984 to 2000. Of these patients, 51 (68%) were alive at a median follow-up of 98 months (range 34-217 months). Nine (18%) patients relapsed and seven (14%) received donor lymphocyte transfusions. Quality of life (QoL) was assessed cross-sectionally using the EORTC QLQ-C30, a Leukaemia-BMT-specific module and questionnaires on sexual functioning, fertility and late effects. A total of 46 (90%) replied. Scores for Role (P=0.018) and Cognitive (P<0.001) function were significantly lower when compared to an age-adjusted general population. Dyspnoea (P=0.022) and Financial Difficulties (P<0.001) were significantly more common in the SCT group. No difference was found for scores in the Physical, Emotional and Social domains or the overall Global Health Status/QoL. Decreased sexual functioning was found in one-third of respondents. Although most BMT recipients reported a good QoL, a minority have difficulty with reintegration into professional roles and consequent monetary problems. Identified cognitive and sexual impairments highlight the need for long-term access to psychosocial support.

ABO Blood-Group System↗
PubMed2003

Impaired visceral sensitivity to acid reflux in patients with Barrett's esophagus. The role of esophageal motility*.

Patients with Barrett's esophagus have been reported to have impaired visceral sensitivity to acid perfusion and distension compared with non-Barrett's refluxers, but the mechanism is poorly understood. Esophageal motility and clearance mechanisms may be important, and this study explored the relationship of motility with symptoms. Seventy-four patients with Barrett's esophagus were compared with 216 patients with gastro-esophageal reflux disease (GERD) with abnormal acid reflux scores, and 50 symptomatic patients who had normal acid exposure. All patients had esophageal manometry and 24-h pH monitoring. Thirty-six Barrett's patients also had 24-h bile reflux monitoring. Symptoms were assessed by Symptom Index (SI) during 24-h pH monitoring. Barrett's patients with normal motility had a significantly lower SI than GERD patients for similar acid exposure (P < 0.001). Barrett's patients with abnormal motility had higher acid exposure than those with normal motility (P < 0.05), but the SI values for this group was not significantly different from the GERD patients. SI and Bile reflux in Barrett's esophagus was not significantly different in patients with normal or abnormal motility. Barrett's patients had less sensitivity than GERD patients for similar acid exposure. Normal motility in Barrett's esophagus is associated with the poorest sensitivity and the presence of increased acid exposure is required in order to achieve sensitivity levels comparable with GERD patients.

Adolescent↗
PubMed2002

Haemodynamic changes caused by oxytocin during caesarean section under spinal anaesthesia.

The haemodynamic effects of oxytocin receive scant attention in pharmacology texts, but may be clinically significant in vulnerable patients. Despite prescriber information recommending a dose of 5 international units by slow i.v. injection, it is the authors' experience that it is very common practice in the UK to give 10 units as a rapid injection. We therefore conducted a randomised, double-blind study of the haemodynamic changes induced by rapid bolus of 5 or 10 units of oxytocin in 34 healthy term parturients at caesarean section under spinal anaesthesia. There was a small but statistically significant (P < 0.05) reduction in mean arterial pressure from baseline 30 s after a 10-unit bolus. However, large, statistically significant increases in heart rate and cardiac output occurred 1 min after 5 units and 2 min after 10 units. These changes peaked 1 min after oxytocin administration and were greater in the 10-unit group (P < 0.05). The importance of these findings is that some women with hypovolaemia or cardiac disease may be unable to mount these compensatory responses and are therefore at risk of haemodynamic collapse after oxytocin boluses. This has been illustrated by a maternal death reported to the Confidential Enquiries into Maternal Deaths in the United Kingdom. The need to adhere to a dose regimen of 5 units by slow injection needs re-emphasis, but no evidence exists to claim that even this will be haemodynamically inert. We therefore recommend that oxytocin boluses be avoided in women with hypovolaemia or cardiac disease.

Clinical Trial↗
PubMed1999

High rate of human T lymphotropic virus type IIa infection in HIV type 1-infected intravenous drug abusers in Ireland.

Serological and molecular analyses of a cohort of HIV-1-infected intravenous drug abusers (IVDAs) (n = 103) in Dublin, Ireland have demonstrated that 15 of 103 (14.6%) were infected with HTLV-II, which is the highest infection rate yet recorded for any European country. Restriction fragment length polymorphism (RFLP) analysis of the env region of the provirus demonstrated that the infection involved only the HTLV-IIa subtype; the HTLV-IIb subtype was not detected. Phylogenetic analysis of the nucleotide sequences of the long terminal repeat (LTR) confirmed infection with the HTLV-IIa subtype, and demonstrated that the viruses clustered closely with HTLV-IIa isolates from North American IVDAs. Previous observations that IVDAs in southern Europe, specifically Spain and Italy, appear to be infected predominantly with the HTLV-IIb subtype, along with the present report and evidence that IVDAs in Sweden are infected with the HTLV-IIa subtype, suggest different origins of HTLV-II infection in Europe.

Adult↗
PubMed1999

Transmission rates of hepatitis C virus by different batches of a contaminated anti-D immunoglobulin preparation.

BACKGROUND AND OBJECTIVES: The aim of this study was to determine the hepatitis C virus (HCV) infection rate of recipients of different batches of anti-D immunoglobulin associated with an outbreak of HCV infection which occurred in 1977 and its relationship to the polymerase chain reaction (PCR) status of the implicated batches. This study was undertaken to determine the predictive value of HCV genome detection and quantification for subsequent infection in recipients of an HCV-contaminated anti-D immunoglobulin product for intravenous use. MATERIALS AND METHODS: Sera from recipients of anti-D were tested by HCV enzyme immunoassay and if found positive were subsequently tested by recombinant immunoblot assay and HCV PCR in a national HCV anti-D screening programme set up in 1994. The HCV status of 1,342 known recipients of infectious or potentially infectious batches has been compared to the amount of HCV RNA in the anti-D batch they received so as to determine the value of PCR in the prediction of infectivity in immunoglobulin preparations. RESULTS: It has been demonstrated that HCV-infected plasma derived from batches of anti-D showing levels of viral genome in excess of 10(4) genomes per millilitre led to infection of up to 60% of recipients. In contrast, batches with undetectable levels of HCV genome very rarely transmitted infection. CONCLUSIONS: The presence of HCV RNA in intravenous immunoglobulin preparations which have not undergone a specific viral inactivation step is a predictor of HCV infection in recipients.

Disease Outbreaks↗
PubMed1999

A second outbreak of hepatitis C virus infection from anti-D immunoglobulin in Ireland.

OBJECTIVE: To investigate the infectivity for hepatitis C virus (HCV) of intravenous anti-D immunoglobulin batches manufactured in Ireland between 1991 and 1994. METHODS: Women who had received anti-D manufactured between 1991 and 1994 were screened for serological markers of HCV infection and for the presence of HCV RNA by RT-PCR amplification and virus genotyping. RESULTS: 44 women exposed to anti-D manufactured between 1991 and 1994 were polymerase chain reaction positive for HCV RNA, 19 of whom were infected with genotype 3a virus shown by phylogenetic analysis of the NS5B gene to be closely related to that from the single implicated donor. CONCLUSIONS: Anti-D manufactured in 1991-1994 transmitted infection of HCV genotype 3a. The prevalence of HCV-specific antibody in anti-D recipients was relatively low (0.59%), consistent with the low level of virus RNA in these anti-D batches.

Disease Outbreaks↗
PubMed1999

Increased urinary nitric oxide metabolites in patients with multiple sclerosis correlates with early and relapsing disease.

Nitric oxide (NO) has been implicated in the immunopathogenesis of MS as a potential mediator of neuronal loss. To investigate the role of.NO in the development of progressive disease we measured the NO metabolites (nitrate and nitrite) and neopterin, in the urine of 129 patients with demyelinating disease (DD): 23 with clinically isolated syndromes compatible with demyelination and in 46 relapsing remitting (RR) and 60 patients with progressive MS. Eighty-nine of these 129 patients underwent Gd-enhanced MRI. In addition 58 normal control subjects (NC), 19 AIDS and 35 rheumatoid arthritis (RA) patients were studied. Patients with DD, AIDS and RA had significantly elevated urinary nitrate plus nitrite (nit : creat. urine) and neopterin (neopt : creat.urine) to creatinine ratios compared to NC subjects. (Median[25th - 75th%] nit : creat.urine: NC=1183[962 - 1365] vs DD=1245[875 - 2403], AIDS=1686[1231 - 2531], and RA=1950[1214 - 2726] mumol/mol, P<0.001 and median[25th - 75th%] neopt : creat.urine: NC=99[76 - 151] vs DD=163[119 - 266], AIDS=972[653 - 1456], and RA=389[257 - 623] mu mol/mol, P<0.001). Patients with early DD and RR MS had significantly elevated nit : creat.urine compared to patients with progressive MS (nit : creat. urine: 1612[1020 - 2733] vs 1159[790 - 1641] mu mol/mol, P=0.006). The nit : creat.urine and neopt : creat.urine did not correlate with clinical relapse or MRI activity. Excretion of.NO metabolites is increased in patients with early or relapsing-remitting disease.NO appears to be a double-edged sword, mediating tissue damage and modulating complex immunological functions which may be protective in MS.

Acquired Immunodeficiency Syndrome↗
PubMed1999

The use of interpleural analgesia using bupivacaine for pain relief in advanced cancer.

The use of interpleural analgesia is described in six patients with a variety of advanced malignancies suffering from pain uncontrolled by opioids. The benefits and complications of the technique are discussed including management of the catheters at home and the measurement of plasma bupivacaine concentrations. Interpleural analgesia can provide good analgesia in a small, selected population of patients with otherwise uncontrolled pain of malignant origin.

Adult↗
PubMed1998

Psychosocial adaptation of patients and families following bone marrow transplantation: a prospective, longitudinal study.

Using a prospective, repeated measures design, this study investigated the psychosocial functioning of patients and a close relative pre- and post-allogeneic and autologous bone marrow transplantation (BMT). All patients (n = 28) undergoing BMT in a 1 year period, and their relatives, were interviewed 1 week pre-transplant and at 3, 6 and 12 months post-BMT, using quantitative and qualitative measures. Pre-transplant data revealed a high level of anxiety (61% with moderate to severe anxiety), and a low level of depression (14% with moderate to severe depression). Twelve patients died in the study period. For the surviving patients there was a statistically significant improvement in physical, psychological and social functioning. Most relatives (88%) reported considerable psychological distress pre-transplant and at 3 months post-transplant, but this was largely resolved by 12 months post-transplant. Significant correlations between the relative's distress and patient's physical and psychological wellbeing were observed at 3 months post-transplant, but not at the other assessment points. The findings from this study will help in counselling patients and their relatives as to what to expect in the year following BMT.

Adaptation, Psychological↗