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Biomedical subjects

J Duggan

Publications and source records attributed to J Duggan.

At least 37 records · Page 2Linked to original sources
PubMed1994

Ambulatory blood pressure monitoring.

Non-invasive measurement of blood pressure in ambulatory humans began in the 1960s. Ambulatory devices have been modified over the years and are now pocket-sized, with almost noiseless pumps. Their accuracy must be validated by independent laboratories using a standardised protocol. Twenty-four-hour ambulatory monitoring offers considerable advantages over conventional measurement, including avoidance of error associated with conventional measurement, elimination of white-coat effect and the provision of a series of blood pressure readings over the time period rather than a one-off measurement. In clinical practice, 24-hr monitoring provides valuable assistance in both the diagnosis and treatment of hypertension, in particular, in the selection of drug and dosage regimen. In the research setting, 24-hr monitoring plays an important role in establishing dose-response relationships and the duration of action of new drugs. It also has a role in the design of antihypertensive trials by ensuring that those with white-coat hypertension are excluded and by reducing the number of subjects necessary for recruitment. Although 24-hr ambulatory blood pressure is a better predictor of target organ damage, definitive evidence as to whether it is a better predictor of prognosis in hypertension awaits the results of longitudinal studies, which are now underway.

Blood Pressure Determination↗
PubMed1994

Determination of the hemodynamics and histamine release of rocuronium (Org 9426) when administered in increased doses under N2O/O2-sufentanil anesthesia.

The cardiovascular effects, histamine release potential, and pharmacodynamics of rocuronium were determined in adult patients randomized to receive rapid (5 s) intravenous (i.v.) bolus doses of 600, 900, or 1200 micrograms/kg (2.0, 3.0, and 4.0 times the ED95) with maintenance doses of 150 micrograms/kg. There were no statistically significant hemodynamic effects (heart rate, blood pressure, mean arterial pressure [MAP] or electrocardiogram [ECG]) after administration of rocuronium. There were no increases in plasma histamine levels at 1, 3, and 5 min after the rapid i.v. bolus of rocuronium as determined by a new radioimmunoassay (RIA) with a sensitivity for histamine quantification of 0.05 ng/mL. Endotracheal intubation was successfully performed 6 min after rocuronium administration (and after plasma samples were obtained). The mean +/- SD clinical durations of 600-, 900-, and 1200-micrograms/kg intubating doses of rocuronium under N2O/O2-sufentanil anesthesia were 45 +/- 20 min, 66 +/- 16 min, and 85 +/- 22 min, respectively. We conclude that rocuronium can be administered safely over a wide range of doses (2-4 x ED95), with minimum hemodynamic effects or histamine release.

Adult↗
PubMed1993

The association of age with plasma arginine vasopressin and plasma osmolality.

We investigated the association of age with supine and ambulant plasma osmolality (pOSM) and arginine vasopressin (AVP). Twenty-eight healthy-status-defined subjects were studied. Following an overnight fast, blood samples were withdrawn after one hour supine rest and two hours' ambulation. Neither supine nor ambulant pOSM nor AVP varied significantly with age. The results suggest that in healthy subjects age does not influence plasma osmolality or AVP.

Adult↗
PubMed1993

Aging and human hormonal and pressor responsiveness to angiotensin II infusion with simultaneous measurement of exogenous and endogenous angiotensin II.

A decline in the function of the renin angiotensin aldosterone system may induce adaptive changes in response to angiotensin II (ANG II) with age. We have examined platelet ANG II receptor density, blood pressure and aldosterone responses to ANG II [Asn1, Val5-ANG II] (Hypertensin, Ciba Geigy, Horsham, Sussex, England) infusion in 8 young, 24 to 30 years, and 8 older, 54 to 65 years, healthy volunteers. To measure circulating ANG II, we established a new method for specific and simultaneous measurement of exogenous [Asn1, Val5] (Hypertensin) and endogenous [Asp1,Ile5] ANG II in plasma by using isocratic HPLC and radioimmunoassays with cross-reacting antibodies and compared results with immunoreactive ANG II which was measured conventionally using monoclonal antibodies. Baseline endogenous ANG II (Asp1,Ile5-ANG II) levels in venous plasma were marginally, but not significantly, lower in the old [mean (95% confidence limits): 3.4 (< 0.1 to 7.7) v 3.7 (1.2 to 6.2), fmol/mL] and during suppression by the Hypertensin infusion appeared consistently, but not significantly, lower in the old [0.9 (0 to 3.1) v 2.1 (0.6 to 3.7), after 3 ng/kg/min], while the same infusion rate in young and old resulted in similar plasma Hypertensin levels. Baseline systolic blood pressure (SBP) was similar in both groups but the percentage increases in SBP at infusion rates of 1, 3.0, and 10 ng/kg/min were greater in the old than in the young (9.1 v 2.8, P < .05; 16.3 v 8.0, P < .01; 30.4 v 14.0%, P < .001, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Causes of hospital-acquired septicaemia--a case control study.

Hospital-acquired septicaemia is common and an important cause of morbidity and expense. Few studies have explored its cause by comparing features of people who do and do not develop septicaemia--the aim of this study. All blood cultures were monitored over one year in a 400-bed tertiary care hospital where special care is taken with intravenous cannulae to prevent septicaemia. Cases had at least one positive blood culture taken at least 48 h after admission. The nearest two patients in the same ward were controls, and information was abstracted on all three from the hospital records by a research nurse. There were 84 cases during the 12 months (3.8 per 1000 admissions) and 167 controls. Univariate odds ratios (95% CI) were 5.57 (2.06-15.95) with the presence of a central venous line, 3.40 (1.16-16.40) with total parenteral nutrition, 2.41 (1.30-4.32) with blood transfusion, 2.10 (1.16-4.56) with immunosuppressive disease, 2.06 (1.02-4.44) with the presence of a urinary catheter and 0.32 (0.17-0.69) with recent surgery. Conditional logistic regression identified a central venous line and blood transfusion to be independent risk factors for septicaemia, odds ratios (and 95% CI) being 5.14 (1.74-15.23) and 2.74 (1.28-5.88), respectively, while recent surgery and antibiotic prophylaxis were independently 'protective' at 0.31 (0.12-0.79) and 0.38 (0.16-0.90), respectively. Thus, in a hospital where great care has been taken to avoid septicaemia, especially by attention to intravenous cannulae, there were only two independent risk factors for the development of hospital-acquired septicaemia--a central venous line and blood transfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Case-Control Studies↗
PubMed1992

Effects of aging and hypertension on plasma angiotensin II and platelet angiotensin II receptor density.

Plasma renin activity (PRA) declines with age in normal individuals, but the effect of age on plasma angiotensin II (ANG II) is less clear. A decline in plasma ANG II with age could result in altered platelet ANG II receptor density since plasma hormone levels influence their target organ receptors. To investigate this possibility, PRA, plasma ANG II, and platelet ANG II receptor density were examined in 17 young, 12 middle-aged, and 14 elderly healthy normotensive volunteers. To assess whether hypertension altered receptor density, these variables were also examined in 23 hypertensive patients. In normotensives, there was a negative correlation between age and PRA (r = -0.43, P < .05), no significant change in basal plasma ANG II with age, and a weak positive correlation between age and ANG II receptor density (r = 0.34, P < .05). Multiple regression analysis revealed that the relationship between age and ANG II receptor density was independent of the associated rise in mean arterial pressure with age (P < .05). Platelet ANG II receptor density was not significantly related to PRA or plasma ANG II. ANG II receptor affinity did not change with age. Neither PRA nor ANG II receptor density or affinity differed between hypertensives and normotensives of similar mean age, but plasma ANG II was significantly lower in hypertensives compared with normotensives. We concluded that aging is associated with a decline in supine PRA. The small decrease in plasma ANG II was not significant. Platelet ANG II receptor density increased with age primarily due to a small group of elderly subjects with elevated receptor density. There was no change in ANG II receptor density or affinity in hypertensives despite apparently lower plasma ANG II in these patients.

Adult↗
PubMed1991

Plasma atrial natriuretic peptide concentration and platelet atrial natriuretic peptide binding site density in ageing and hypertension.

1. Ageing and hypertension are associated with changes in the way in which the body handles sodium. This may involve changes in plasma atrial natriuretic peptide concentration, since atrial natriuretic peptide is a regulator of sodium handling by the kidney and the plasma atrial natriuretic peptide concentration is increased in both ageing and hypertension. An increase in the plasma atrial natriuretic peptide concentration could also be associated with a change in atrial natriuretic peptide receptor density, possibly involving down-regulation. 2. To investigate these possibilities plasma atrial natriuretic peptide concentration and platelet atrial natriuretic peptide binding site density were measured in 18 young, 11 middle-aged and 12 elderly healthy subjects and in 23 patients with mild to moderate essential hypertension. 3. In normotensive subjects, the plasma atrial natriuretic peptide concentration increased with age (r = 0.49, P less than 0.01) and was significantly higher in elderly than young subjects (mean +/- SEM, 31.9 +/- 4.5 versus 18.3 +/- 2.0 pmol/l, P less than 0.05). The plasma atrial natriuretic peptide concentration increased with the mean arterial pressure in normotensive subjects (r = 0.47, P less than 0.01). Multiple regression analysis did not show independent relationships between the plasma atrial natriuretic peptide concentration and either age or mean arterial pressure in normotensive subjects alone. However, when normotensive subjects and hypertensive patients were considered together, multiple regression revealed both age and mean arterial pressure as independent predictors of the plasma atrial natriuretic peptide concentration (P less than 0.05, P less than 0.01, respectively). In normotensive subjects, the platelet atrial natriuretic peptide binding site density did not change with age (r = 0.19, P = 0.27).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

The effects of age on platelet intracellular free calcium concentrations in normotensives and hypertensives.

We have investigated relationships between age, blood pressure and intracellular calcium concentration in platelets from normotensives and hypertensives. In normotensives, there were positive correlations between age and platelet intracellular calcium concentration (r = 0.76, P less than 0.001), age and mean arterial pressure (MAP; r = 0.55, P less than 0.01) and MAP and platelet intracellular calcium concentration (r = 0.45, P less than 0.01). Multiple regression analysis revealed that age was the primary determinant of platelet intracellular calcium concentration in normotensives. The effect of MAP on platelet intracellular calcium concentration when adjusted for age was not significant (P = 0.73). In hypertensives, there was no significant relationship between age and platelet intracellular calcium concentration (r = 0.15, P = 0.43), age and MAP (r = 0.17, P = 0.37) or MAP and platelet intracellular calcium concentration (r = -0.27, P = 0.15). Overall, platelet intracellular calcium concentration was significantly higher in hypertensives than in age-matched normotensives (P less than 0.05). Within the age groups examined, platelet intracellular calcium concentration was significantly higher only in younger hypertensives when compared with controls of a similar mean age (P less than 0.001). Thus, age, in addition to hypertension, is an important determinant of platelet intracellular calcium concentration.

Adult↗
PubMed1989

Diagnosis, complications and treatment of Takayasu's arteritis.

Takayasu's arteritis is a large vessel vasculitis involving the aorta and it's major branches. Clinical diagnosis in the early stage is important as the disease may then be treatable. We present the first two cases ever reported in the Irish literature.

Adrenal Cortex Hormones↗
PubMed1989

A double-blind evaluation of captopril in elderly hypertensives.

To establish the role of angiotensin converting enzyme inhibitors in the management of hypertension in the elderly, 16 patients were treated with captopril in a randomized double-blind placebo-controlled cross-over study. Clinic blood pressure, ambulatory blood pressure, renal function and mental performance, with emphasis on mood and psychological well-being, were assessed. Twelve patients, aged 73 (+/- 4.4) years, completed the study. The doses of captopril used were 50 mg (11 patients) and 25 mg (one patient) twice daily for 4 weeks. Mean (+/- s.e.m.) clinic sitting blood pressure during captopril therapy was significantly lower than during administration of placebo (172 +/- 4.5/83 +/- 25 versus 188 +/- 4.4/89 +/- 3.4 mmHg; P less than 0.001/P less than 0.05). Mean ambulatory blood pressure was also significantly lower on captopril treatment than during administration of placebo (166 +/- 5.3/87 +/- 1.6 versus 179 +/- 5.1/94 +/- 2.4 mmHg; P less than 0.02/P less than 0.02) and this effect was sustained over the dosing interval. Renal blood flow and mental performance were unaltered by treatment. Gastrointestinal discomfort occurred in two patients, one of whom was withdrawn and cough developed in one patient. We conclude that captopril is effective as monotherapy in lowering blood pressure in the elderly.

Aged↗
PubMed1989

Radiculopathies of structural origin.

In dealing with foot pain of a radicular nature, it is important to interpret the clinical signs and symptoms of the pathology carefully and arrive at an adequate diagnosis. All appropriate ancillary aids should be used to help confirm the diagnosis. Appropriate treatment plans will follow; most often they will include referrals to qualified orthopedic specialists. In this sense, the treatment of lower-extremity radiculopathy is seen as a multidisciplinary problem. The podiatrist has the opportunity to make the diagnosis, explain the problem to the patient, and perhaps deal with the resolution of the pathology. This article attempted to present a differential diagnosis of a structural radiculopathy presenting in the lower extremity. It is hoped that the discussion of symptomatology, diagnostic aids, and numerous illustrations help to add to the knowledge of this disease process.

Foot↗
PubMed1988

Morphometry of nerve fiber bundle pores in the optic nerve head of the human.

The axons of retinal ganglion cells form fascicles that leave the globe through pores in the optic nerve head formed by beams of glia and collagen. In eyes obtained at time of autopsy of 17 normal subjects of various ages, these pores were counted and measured in the lamina choroidalis and lamina scleralis of the nerve heads. The number of pores at the scleral level was 1.48 times (0.18, 95% confidence interval) greater than at the choroidal level, and the pores were proportionately smaller at the scleral level. No significant change in the numbers of pores or the area of the nerve head at either level was found with age. The proportion of the nerve head devoted to pores decreased significantly with age. Since the pores contain primarily nerve fibers, the slope of this decrease suggests the loss to be about 5% of fibers per decade after age 30.

Adult↗
PubMed1988

Extradural block with bupivacaine: influence of dose, volume, concentration and patient characteristics.

In a randomized, double-blind study the influences of the characteristics of both solution (dose, volume, concentration) and patient (age, weight, height, body mass index) on the development of extradural blockade produced by a low lumbar injection of bupivacaine were investigated. Thirty patients aged between 20 and 50 yr received one of three solutions (groups I-III, respectively): 0.75% 10 ml (75 mg); 0.5% 15 ml (75 mg); 0.75% 15 ml (112.5 mg). A further 20 patients older than 50 yr received 0.75% bupivacaine 10 ml (group IV, n = 10) or 15 ml (group V, n = 10). The number of segments blocked at maximal extent of block was virtually the same in each group: group I (0.75% 10 ml) 13.3 (SD 1.4); group II (0.5% 15 ml) 14.1 (2.9); group III (0.75% 15 ml) 13.8 (2.2); group IV (0.75% 10 ml) 14.2 (2.1); group V (0.75% 15 ml) 16.7 (3.1). The larger dose of bupivacaine (112.5 mg) produced the fastest onset and longest duration of block. Onset and recovery intervals were similar with 0.75% and 0.5% solutions when administered at the same dose (75 mg in 10 ml or 15 ml). There was no correlation between the level of block and the age, weight and height of the patient. In patients who received 15-ml injections, there was a positive association between the upper level of block and body mass index.

Adult↗