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Biomedical subjects

A Ward

Publications and source records attributed to A Ward.

At least 19 recordsLinked to original sources
PubMed1992

Arylamine N-acetyltransferase in human red blood cells.

N-Acetyltransferase activities associated with erythrocytes from 20 individuals have been determined with p-aminobenzoic acid as substrate. A three-fold variation in Vmax is found. The N-acetyltransferase genotype of the individuals has been determined and there is no correlation between the extent of acetylation measured in the individuals' erythrocytes and the inheritance of alleles at the polymorphic NAT locus. Folate is confirmed to be an inhibitor of arylamine N-acetyltransferase activity measured in erythrocytes. The content of folate in erythrocytes of individuals also varies. The individual with the maximum folate content has the minimum N-acetyltransferase activity. The monomorphic N-acetyltransferase gene from individuals spanning the range of N-acetyltransferase activity have been amplified, using the polymerase chain reaction. The pattern of restriction enzyme digestion of the monomorphic N-acetyltransferase gene with a series of eight restriction enzymes is the same for individuals spanning the activity range of arylamine N-acetyltransferase in their erythrocytes.

4-Aminobenzoic Acid↗
PubMed1992

Treadmill validation of an over-ground walking test to predict peak oxygen consumption.

The purpose of this study was to determine whether a test developed to predict maximal oxygen consumption (VO2max) during over-ground walking, was similarly valid as a predictor of peak oxygen consumption (VO2) when administered during a 1-mile (1.61 km) treadmill walk. Treadmill walk time, mean heart rate over the last 2 full min of the walk test, age, and body mass were entered into both generalized (GEN Eq.) and gender-specific (GSP Eq.) prediction equations. Overall results indicated a highly significant linear relationship between observed peak VO2 and GEN Eq. predicted values (r = 0.91), a total error (TE) of 5.26 ml.kg-1.min-1 and no significant difference between observed and predicted peak VO2 mean values. The peak VO2 for women (n = 75) was predicted accurately by GSP Eq. (r = 0.85; TE = 4.5 ml.kg-1.min-1), but was slightly overpredicted by GEN Eq. (overall mean difference = 1.4 ml.kg-1.min-1; r = 0.86; TE = 4.56 ml.kg-1.min-1). No significant differences between observed peak VO2 and either GEN Eq. (r = 0.85; TE = 4.3 ml.kg-1.min-1) or GSP Eq. (r = 0.85; TE = 4.8 ml.kg-1.min-1) predicted values were noted for men (n = 48) with peak VO2 values less than or equal to 55 ml.kg-1.min-1. However, both equations significantly underpredicted peak VO2 for the remaining high peak VO2 men (n = 22). In conclusion, the over-ground walking test, when administered on a treadmill, is a valid method of predicting peak VO2 but underpredicts peak VO2 of subjects with observed high peak VO2 values.

Adult↗
PubMed1992

Short term effect of oxygen on renal haemodynamics in patients with hypoxaemic chronic obstructive airways disease.

BACKGROUND: Oxygen therapy is effective in the prevention and treatment of oedematous exacerbations of cor pulmonale. As renal blood flow is reduced in cor pulmonale a study was designed to investigate whether one of the beneficial effects of oxygen was to increase renal blood flow. The effect of oxygen therapy on renal haemodynamics measured noninvasively was examined in patients with chronic obstructive airways disease and previous episodes of oedema. METHODS: Renal blood flow waveforms were recorded in a single vessel by colour flow Doppler ultrasound in nine hypoxaemic patients (PaO2) (arterial oxygen tension < 8 kPa while they were breathing air) with chronic obstructive airways disease and previous oedema and eight age matched normoxaemic volunteers (arterial oxygen saturation (SaO2) 97% or more when breathing air) while they were breathing air and oxygen. SaO2 and transcutaneous PaO2 (TcPO2) and PaCO2 (TcPCO2) were monitored. Five renal velocity profile recordings were made from the same segmental vessel with the patient breathing room air for one hour followed by oxygen titrated to achieve an oxygen saturation of 95% or more without a rise in TcPCO2 for 15 minutes. Control subjects breathed 35% oxygen. RESULTS: No significant change in the pulsatility index (a measure of distal vascular resistance) or mean height of the waveform (Tamx, a measure of renal blood flow) occurred in the control subjects while they were breathing air or oxygen. The pulsatility index of the patients with chronic obstructive airways disease was significantly greater than that in the control subjects breathing air (1.44 (SD 0.28) v 1.03 (0.14). Breathing oxygen was associated with an increase in TcPO2 in the patients (from 6.9 (1.9) to 11.5 (0.7) kPa), a fall in pulsatility index (from 1.44 (0.28) to 1.26 (0.14) and an increase in Tamx (from 0.187 (0.055) to 0.234 (0.087) m/s). CONCLUSIONS: The results suggest that renal vascular resistance is increased in patients with chronic obstructive airways disease and hypoxaemia and that short term oxygen therapy reduces renal vascular resistance and increases blood flow. Some of the benefits of oxygen therapy in cor pulmonale may be due to improvements in renal haemodynamics.

Aged↗
PubMed1992

Athletic heart syndrome.

AHS is a benign condition consisting of physiologic adaptations to the increased cardiac work load of exercise. Its primary features are biventricular hypertrophy and bradycardia associated with normal systolic and diastolic function. In addition, the alterations in cardiac structure are related to the type of training with dynamic training causing proportionally greater dilation and static training primarily increased wall thickness. AHS is associated with abnormalities in ECG, radiograph, and echocardiographic findings. It is important to be aware of these changes so that they are not misinterpreted to represent pathologic states. In particular, the distinction between AHS and HCM can be difficult, although certain historic and echocardiographic features can help differentiate the two.

Animals↗
PubMed1979

Mean steady-state plasma concentrations of labetalol in patients undergoing antihypertensive therapy.

1 Mean steady-state plasma concentrations of labetalol (labetalol Css) in 17 hypertensive patients undergoing chronic treatment with this drug, have been examined in relation to dose, fall in BP, and beta-blockade. 2 A significant relationship (rs = 0.81, P less than 0.001) was observed between labetalol Css and daily dose. 3 No correlation was found between labetalol Css and antihypertensive response. 4 In thirteen patients, there seemed to be significant relationship between labetalol Css and beta-blockade (rs = 0.72, P less than 0.005). In three patients, the degree of beta-blockade was disproportionate to the drug concentration.

Adult↗
PubMed1978

A comparison of body fat determined by underwater weighing and volume displacement.

Two hydrostatic techniques, underwater weighing and water displacement, were used to determine body fat for 67 volunteer men between 25 and 61 yr of age (-/x=41 yr). All tests were administered in random order in the morning on the same day while subjects were in the postabsorptive state. Test-retest reliabilities for the underwater weighing and water displacement techniques were 0.995 and 0.96, respectively. The correlation between the two hydrostatic techniques was r=0.96. The mean percent fat determined by underwater weighing (-/x=20.1 +/- 6.4) and water displacement (-/x=19.4 +/- 6.1) were significantly different (t=28.16; df=65; P less than 0.001). These analyses showed that both techniques were reliable in measuring percent body fat, but produced slight systematic differences. Regression equations were provided to adjust for the difference.

Adipose Tissue↗
PubMed1978

Endometrial factors under treatment with oestrogen and oestrogen/progestogen combinations.

In a continuing prospective study, uterine curettage was undertaken on sixty-four patients attending a Menopause Clinic prior to consideration of gonadal hormone therapy. Two of these patients (3.1%) were found to have endometrial hyperplasia, and subsequently they were not given gonadal hormone therapy. Sixty-two patients with normal endometrium at pre-treatment curettage received cyclical oestrogen regimens or sequential oestrogen/progestogen treatments. Four (30.8%) of the thirteen patients in receipt of cyclical 'high-dose' oestrogens developed cystic glandular hyperplasia, whereas none of the patients taking either cyclical 'low-dose' oestrogens (thirty patients) or cyclical-sequential oestrogen/progestogen regimens (nineteen patients) developed endometrial hyperplasia. Among the patients with a normal endometrium, both before and during cyclical gonadal hormone therapy, regular withdrawal bleeding was experienced by thirty-two patients (51.6%). Breakthrough bleeding occurred in nine (14.5%), while twenty-one patients (33.9%) had no vaginal bleeding. Of the four patients with normal endometrium at pre-treatment curettage who subsequently developed endometrial hyperplasia during cyclical 'high-dose' oestrogen therapy, regular withdrawal bleeding was experienced by two patients, and in one of these breakthrough bleeding also occurred. Furthermore, in the four patients who developed endometrial hyperplasia, this condition occurred within six months in two patients and within 9 and 10 months respectively in the remaining two. In the nineteen patients receiving cyclical sequential oestrogen/progestogen regimens, all had regular withdrawal bleeding, while one patient had breakthrough bleeding during sequential therapy. It is concluded that in those climacteric patients who present with severe menopausal symptoms which necessitate the administration of high-dose oestrogen regimes it is necessary either to undertake both pretreatment uterine curettage or to add a progestogen to the oestrogen in a sequential regimen.

Climacteric↗