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Biomedical subjects

F O'Connor

Publications and source records attributed to F O'Connor.

At least 19 recordsLinked to original sources
PubMed2000

An automated heteroduplex assay for the Pi(A) polymorphism of glycoprotein IIb/IIIa, multiplexed with two prothrombotic genetic markers.

Screening for the PIA polymorphism has been made faster and simpler with the advent of heteroduplex technology. Simultaneous screening for three common prothrombotic polymorphisms pl(A), factor V Leiden, and MTHFR(C677T) has been achieved with multiplex heteroduplex analysis. We describe a quick and simple method for PlA heteroduplex probe production. The probe was multiplexed with heteroduplex probes for MTHFR(C677T) and factor V Leiden polymorphisms in a one tube assay, allowing rapid automated genotyping of all three. This automated multiplex assay was applied to a cohort of 165 patients and showed excellent correlation with gel-based assays, both PAGE and RFLP. This approach will facilitate the analysis of multiple polymorphisms in complex disease in large populations.

Cohort Studies↗
PubMed2000

Injuries during Marine Corps officer basic training.

On average, about 25% of male and 50% of female enlisted recruits sustain one or more injuries during basic training. Because data on military officer populations are sparse, this study investigated injury incidence, injury rates, and modified duty days that occurred during Marine Corps officer basic training (6 weeks in length). Subjects were 480 officer candidates (including 30 females) undergoing training at Quantico, Virginia. The cumulative injury incidence (one or more injuries) was 60.8%, and the injury rate was 3.9 per 1,000 candidate hours of training. There were 378 primary injury encounters (first visit for a specific injury). The highest injury rates occurred during weeks 2, 3, and 6. Male injury categories with the highest rates (injuries per 100 trainees per 1,000 training hours) were blisters (0.68), sprains (0.58), and bone stress reactions (0.40). The highest injury rates in females were for bone stress reactions (1.35). On average, a total of 3.1% of training days constituted modified duty for each candidate. This study provides basic descriptive injury data for this unique military population that can assist in future planning for injury management and preventive interventional strategies.

Absenteeism↗
PubMed1999

Immune responses of cattle to experimental anti-Fasciola hepatica vaccines.

Fasciola hepatica infection of cattle and sheep is an important cause of clinical disease and production losses, and is controlled at present by a combination of chemotherapy and management measures. However, the prospects for the control of F. hepatica infection by vaccination are good, and we have previously shown substantial protection of cattle against experimental challenge infection following immunisation with a combination of the purified fluke-derived enzymes cathepsin L1 (CATL 1), cathepsin L2 (CATL 2) and fluke-derived Hb fraction (FHB). This and other recent studies have also demonstrated fundamental differences between protective and non-protective immune responses to liver fluke infection. In this present study we have further analysed the response of animals to liver fluke challenge following experimental vaccination. Calves were vaccinated with either CATL 2 plus FHB, or CATL 1 plus CATL 2. Partial protection against challenge infection was achieved in both vaccinated groups, with the greatest level of protection (55 per cent reduction in fluke burdens) recorded in the group vaccinated with CATL 1 plus CATL 2. This latter group also showed the greater level of lymphocyte proliferation and the greater production of gamma-INF in response to stimulation with fluke antigen in vitro following challenge. These results are significant in our attempts to characterise the elements within the immune response to vaccination which are protective.

Animals↗
PubMed1998

Which arterial and cardiac parameters best predict left ventricular mass?

BACKGROUND: Many cardiovascular and noncardiovascular parameters are thought to be determinants of left ventricular mass (LVM). Complicated interactions necessitate the simultaneous measurement and consideration of each to determine their individual and collective impact on LVM. We undertook such a comprehensive study. METHODS AND RESULTS: The influence of anthropometry, cardiac size and contractility, arterial structure and function, as well as indices of lifestyle, physical activity, and dietary salt intake on LVM (by two-dimensionally guided M-mode echocardiography) was analyzed in 1315 Chinese subjects who were either normotensive or had untreated hypertension. Effects of many cardiac and arterial factors were assessed. In univariate analysis, almost all measured noncardiovascular, cardiac, and arterial variables were significantly correlated with LVM. In multivariate linear regression analyses, when age, sex, body habitus, fasting serum C-peptide level, dietary salt, physical activity, and lifestyle were accounted for, the optimum multivariate linear regression main effects model had an adjusted model r2 of 0.740, with 98% of the model variance accounted for by the 5 independent determinants of LVM: stroke volume (49.6%), systolic blood pressure (30.7%), contractility (14.7%), body mass index (1.8%), and aortic root diameter (1.6%). Other proposed arterial indices were significant independent determinants of LVM only when blood pressure was removed from the model and, even then, these indices not only resulted in less powerful prediction but also accounted for only a very small percentage of the total variance of LVM. CONCLUSIONS: In a large population, we (1) confirmed that age, body habitus, and some indexes of arterial structure and function are independent determinants of LVM; (2) found aortic diameter to be an independent structural determinant of LVM; (3) demonstrated that the effects of the derived measures of arterial function were small and provided no better predictive power than blood pressure alone; and (4) showed that when the best measures of cardiac and vascular load were included, the single most potent predictor was an index of left ventricular size.

Adult↗
PubMed1996

[Infectious endocarditis caused by Q fever].

A case of aortic valve endocarditis caused by Coxiella burnetii and operated on with success is reported. The patient is doing well at 18 months follow up. Diagnosis of Q-fever endocarditis was made by high antibodies against phase I Coxiella burnetii antigens titration and by demonstration of aortic valvular vegetations by bidimensional echocardiography. Our patient suffered emergency aortic valve substitution due to acute hemodynamic failure and started a long-term treatment with doxycycline and rifampicin. Some interesting aspects about the diagnosis and treatment of this patient are reviewed because long-term follow-up and serological controls are still rare in the literature.

Anti-Bacterial Agents↗
PubMed1996

Osteogenesis imperfecta and coronary artery surgery. A case report.

A new case of Osteogenesis Imperfecta (OI) suffering ischemic heart disease is reported. The patient was successfully operated on in our Institution and the bibliographic search showed only another case of such an association of diseases successfully treated by surgery. This patient proves that coronary artery surgery procedures are possible when OI complicates the cardiac ischemic syndrome.

Coronary Artery Bypass↗
PubMed1995

Left ventricular diastolic filling performance in older male athletes.

OBJECTIVE: To determine whether older men who have undergone intensive endurance training over many years demonstrate less age-associated impairment of early diastolic left ventricular (LV) filling performance than their sedentary peers. DESIGN: Cross-sectional prospective study. SETTING: Community-dwelling research volunteers. PARTICIPANTS: Sixteen older competitive male endurance athletes aged 52 through 76 years and 17 young (< 40 years) and 23 older (52 through 76 years) sedentary control subjects from the Baltimore Longitudinal Study of Aging. INTERVENTION: All subjects underwent resting Doppler echocardiography and determination of maximal aerobic capacity (VO2max) during graded treadmill exercise. Doppler echocardiographic studies were interpreted without knowledge of the subject's age or exercise habits. MAIN OUTCOME MEASURES: Doppler-derived measures of LV diastolic filling performance: peak early (E) filling velocity, peak late (A) filling velocity, ratio of peak E to peak A velocities (E/A), and atrial filling fraction. RESULTS: Older athletes demonstrated higher VO2max (47 +/- 6 mL/kg per minute [mean +/- SD]) than either the young controls (41 +/- 7 mL/kg per minute) or older controls (30 +/- 7 mL/kg per minute) (P < .05) as evidence of their superior conditioning status. However, peak E diastolic LV filling velocity was higher in young controls (79 +/- 17 cm/s) than in older athletes (56 +/- 15 cm/s) or older controls (68 +/- 18 cm/s) (P < .001). This age difference persisted after normalizing peak E velocity for mitral stroke volume. Peak E/A ratio and atrial filling fraction were also similar in older athletes (1.2 +/- 0.5 and 0.41 +/- 0.1, respectively) and older controls (1.1 +/- 0.4 and 0.41 +/- 0.1, respectively), and differed significantly from corresponding values of 1.7 +/- 0.4 and 0.33 +/- 0.1 in young controls (P < .001 and P < .05, respectively). By multiple regression analysis, age but not treadmill VO2max was a significant predictor of peak E velocity, peak A velocity, peak E/A ratio, and atrial filling fraction. CONCLUSION: Older men with a long history of intensive endurance training demonstrate impaired early diastolic LV filling similar to that of their sedentary peers. Thus, impairment of early diastolic filling appears to be intrinsic to normative aging and not secondary to the reduction in aerobic capacity that accompanies the aging process.

Adult↗
PubMed1995

Impact of age on the cardiovascular response to dynamic upright exercise in healthy men and women.

To examine whether age differentially modifies the physiological response to exercise in men and women, we performed gated radionuclide ventriculography with measurement of left ventricular volumes at rest and during peak upright cycle exercise in 200 rigorously screened healthy sedentary volunteers (121 men and 79 women) aged 22-86 yr from the Baltimore Longitudinal Study of Aging. At rest in the sitting position, age-associated declines in heart rate (HR) and increases in systolic blood pressure occurred in both sexes. Whereas resting cardiac index (CI) and total systemic vascular resistance (TSVR) in men did not vary with age, in women resting CI decreased 16% and TSVR increased 46% over the six-decade age span. Men, but not women, demonstrated an age-associated increase of approximately 20% in sitting end-diastolic volume index (EDVI), end-systolic volume index (ESVI), and stroke volume index over this age span. Peak cycle work rate declined with age approximately 40% in both sexes, but at any age it was greater in men than in women even after normalization for body weight. At peak effort, ejection fraction (EF), HR, and CI were reduced similarly with age while ESVI and TSVR were increased in both sexes; EDVI increased 35% with age and stroke work index (SWI) rose 19% in men, but neither was related to age in women; and stroke volume index did not vary with age in either sex. When hemodynamics were expressed as the change from rest to peak effort as an index of cardiovascular reserve function, both sexes demonstrated age-associated increases in EDVI and ESVI and reductions in EF, HR, and CI. However, the exercise-induced reduction in ESVI and the increases in EF, CI, and SWI from rest were greater in men than in women. Thus, age and gender each have a significant impact on the cardiac response to exhaustive upright cycle exercise.

Adult↗
PubMed1994

Effect of body fat on exercise hemodynamics in sedentary older men.

Morbid obesity is often associated with cardiac dilatation and left ventricular dysfunction. The present study investigated whether a similar relationship exists between mild and moderate obesity and left ventricular reserve function in 28 middle aged and older men (58.6 +/- 6.1 years, mean +/- SD). Subjects had a body mass index of 26.4 +/- 2.9 kg/m2, a percent body fat determined by hydrodensitometry ranging from 9.5% to 33.8%, and were carefully screened to exclude cardiovascular disease. Left ventricular function was assessed by gated blood pool scans at rest and during exhaustive upright cycle exercise. There were no significant relationships between resting or exercise cardiac volumes or ejection fraction with percent body fat; however, peak work rate/kg correlated inversely with percent body fat (r = -0.68, p < 0.0001). Heart rate reserve, defined as heart rate at peak work rate minus resting heart rate, declined significantly with increasing percent body fat (r = -0.47, p = 0.01). End diastolic volume index reserve also tended to decline with increasing percent body fat, but stroke volume index and cardiac index reserve were maintained because the decrease in end systolic volume index from rest to maximal exercise was greatest in those subjects with highest percent body fat (r = -0.41, p = 0.03). Therefore, rest and exercise left ventricular function are not related to percent body fat in healthy older men. However, older more obese men have a smaller increase in heart rate and end diastolic volume and a greater decrease in end systolic volume from rest to peak effort as a mechanism to augment exercise cardiac output.

Body Mass Index↗
PubMed1994

Effects of acute beta-adrenergic receptor blockade on age-associated changes in cardiovascular performance during dynamic exercise.

The cardiovascular response to beta-adrenergic stimulation is markedly blunted with advancing age, and this blunting may underlie some of the prominent age-associated changes in the hemodynamic profile during dynamic exercise. To examine this hypothesis, we administered the nonselective beta-adrenergic receptor blocker propranolol (0.15 mg/kg IV) to 25 healthy normotensive men ages 28 to 72 years from the Baltimore Longitudinal Study of Aging (BLSA) immediately before maximal upright cycle ergometry with 99mTc gated cardiac blood pool scintigraphy. Their hemodynamic responses to exercise were compared with those of 70 age-matched healthy unmedicated male BLSA control subjects. The maximal cycle work rate achieved was similar in propranolol-treated men (158 +/- 32 W) and control subjects (148 +/- 32 W) and declined similarly with age in both groups. Hemodynamics at seated rest were not age-related in either group; however, propranolol-treated men had lower heart rates (HR), systolic blood pressure (SBP), ejection fraction, and cardiac index than control subjects but higher end-diastolic volume index (EDVI) and end-systolic volume index (ESVI) by covariance analysis. At maximal effort, several striking age-drug interactions were evident: Propranolol caused a greater reduction in HR and greater increases in EDVI and stroke volume index (SVI) in younger than in older men. Hence, at maximal work rate, HR declined less with age in the propranolol group (0.46 versus 1.09 beats per minute per year, P < .05 by covariance analysis); EDVI and SVI decreased with age (0.27 and 0.48 mL/m2 per year, respectively) after propranolol compared with increases of 0.47 and 0.16 mL/m2 per year in control subjects, respectively, each P < or = .05 by covariance analysis. The left ventricular contractility index, SBP/ESVI, at exhaustion was reduced by propranolol to a greater extent in younger than older men. Thus, acute beta-adrenergic blockade reverses the age-associated ventricular dilation at end diastole and end systole observed during upright cycle exercise and blunts the decline in maximal HR and myocardial contractility. These data suggest that the age-associated declines in maximal HR and left ventricular contractility during vigorous exercise are manifestations of reduced beta-adrenergic responsivity with advancing age which is partially offset by exercise-induced ventricular dilation.

Adrenergic beta-Antagonists↗
PubMed1994

Age-associated changes in beta-adrenergic modulation on rat cardiac excitation-contraction coupling.

Previous studies have demonstrated that the ability of beta-adrenergic receptor (beta AR) stimulation to increase cardiac contractility declines with aging. In the present study, the control mechanisms of excitation-contraction (EC) coupling, including calcium current (ICa), cytosolic Ca2+ (Cai2+) transient and contraction in response to beta AR stimulation were investigated in ventricular myocytes isolated from rat hearts of a broad age range (2, 6-8, and 24 mo). While the baseline contractile performance and the Cai2+ transient did not differ markedly among cells from hearts of all age groups, the responses of the Cai2+ transient and contraction to beta-adrenergic stimulation by norepinephrine (NE) diminished with aging: the threshold concentration and the ED50 increased in rank order with aging; the maximum responses of contraction and Cai2+ transient decreased with aging. Furthermore, the efficacy of beta AR stimulation to increase ICa was significantly reduced with aging, and the diminished responses of the contraction and Cai2+ transient amplitudes to NE were proportional to the reductions in the ICa response. These findings suggest that the observed age-associated reduction in beta AR modulation of the cardiac contraction is, in part at least, due to a deficit in modulation of Cai2+, particularly the activity of L-type calcium channels.

Aging↗
PubMed1993

Paroxetine binding in the blood platelets of post-traumatic stress disorder patients.

Platelet serotonin (5-HT) uptake, as determined by 3H-paroxetine (PA) binding, was studied in 20 Post-traumatic Stress Disorder (PTSD) patients and 20 normal controls. Kd (an inverse measure of affinity of 3H-PA binding to uptake sites) and Bmax (maximum number of 3H-PA binding sites) of 3H-PA binding were significantly decreased in PTSD patients as compared to normal controls. However, there was no difference in Kd or Bmax between PTSD patients with and without a diagnosis of major depression. The Bmax of 3H-PA binding was negatively correlated with state dependent anxiety score whereas Kd was positively correlated with the Mississippi Scale for Combat-Related PTSD score. The role of serotonergic processes in the psychobiology of PTSD is discussed.

Adult↗