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Biomedical subjects

R G Gosling

Publications and source records attributed to R G Gosling.

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

Aortic compliance measured by non-invasive Doppler ultrasound: application of a personal computer based MkII system and its repeatability.

A non-invasive pulse-wave-velocity Doppler ultrasound technique for the assessment of aortic compliance is described. A computational approach for correcting for the effect of non-chronic changes in blood pressure is considered and applied to compliance measurements performed on an age-select cohort of 70 normotensive, normal healthy volunteers. In order to permit the wider availability of the pulse-wave-velocity Doppler ultrasound technique, the authors have developed a MkII system based on a standard 80486/33 MHz IBM compatible WINDOWS based personal computer; real-time spectral analysis being achieved using a relatively inexpensive but fast analogue to digital signal processing card. An overview of the new apparatus is provided and verification work to compare the repeatability of the MkI and MkII systems is described. Medical disorders such as atherosclerosis, diabetes mellitus, familial hypercholesterolaemia, growth hormone deficiency, and Ehlers-Danlos and Marfan's syndromes have all been shown to affect arterial wall compliance. We suggest that the in vivo clinical measurement of blood pressure corrected aortic distensibility using the MkII system may be a useful, reproducible, non-invasive tool for assessing such patients' susceptibility to atheromatous arterial disease as well as for monitoring their response to therapeutic interventions. Measurements in the aorta may be especially pertinent since the natural history of fatty streaks there tends to parallel that in the coronary vasculature thereby potentially affording a convenient surrogate estimate of coronary heart disease.

Aorta↗
PubMed1994

Aortic distensibility in post-menopausal women receiving Tibolone.

Both oestrogen and androgens have been shown to affect the structural composition and biophysical properties of the arterial wall in vitro. A non-invasive Doppler ultrasound technique, based on the measurement of pulse wave velocity along the thoraco-abdominal aortic pathway, was used to assess aortic compliance C in vivo in 49 normotensive, normal, healthy post-menopausal female subjects. 23 of the women had been receiving Tibolone, a synthetic steroid structurally related to norethisterone, for at least 3 years. Since C varies with non-chronic changes in blood pressure, an index of intrinsic aortic distensibility, Cp, normally independent of blood pressure, was also calculated. No significant difference was found between the control group and those subjects receiving Tibolone for age, body mass index, systolic blood pressure, diastolic blood pressure, C or Cp. As one would expect the control group Cp values did not show a significant relationship with blood pressure (r = -0.1, not significant). However, in the Tibolone group some dependence of Cp values on pressure still remained (r = -0.58, p < 0.004), suggesting that oral administration of Tibolone had altered the dynamic relationship between structural and functional biophysical properties of the aortic wall in vivo.

Anabolic Agents↗
PubMed1994

Insulin-like growth factor-binding protein-1 is correlated with low density lipoprotein cholesterol in normal subjects.

Insulin-like growth factor-I (IGF-I) has been inversely associated with low-density lipoprotein (LDL) cholesterol in normal women with slightly elevated cholesterol levels and hypothyroid women. More than 95% of IGF-I circulates bound to binding proteins (IGFBPs); of these IGFBP-1 is of particular interest as it is inversely regulated by insulin and is thought to inhibit the action of IGF-I and IGF-II. We examined the relationship between IGFBP-1 and LDL cholesterol in 41 healthy adult subjects. LDL cholesterol correlated with the body mass index (r = 0.40, P < 0.01), sex (r = 0.51, P < 0.001) and IGFBP-1 levels (r = 0.36, P < 0.02). LDL cholesterol did not correlate with age (r = 0.25, P = not significant) or IGF-I (r = 0.06, P = not significant). Upon multivariate regression analysis, sex, body mass index and IGFBP-1 were all independent predictors of LDL cholesterol (all P < 0.05). Elevated IGFBP-1 levels have been associated with an inhibition of serum IGF-I bioactivity in children with insulin-dependent diabetes. IGFBP-1 also appears to inhibit IGF-I hexose-stimulated uptake. IGFBP-1 may also be inhibiting the effect of IGFs on the cellular metabolism of LDL cholesterol.

Adult↗
PubMed1993

Validation and reproducibility of pressure-corrected aortic distensibility measurements using pulse-wave-velocity Doppler ultrasound.

A non-invasive Doppler ultrasound technique is described for the assessment of aortic compliance based on the in vivo measurement of pulse wave velocity along the thoraco-abdominal aortic pathway. A structured protocol, which has been developed to improve the reproducibility of the technique, is validated. A method of correcting for the effect of non-chronic changes in blood pressure on arterial elasticity is considered and applied to compliance measurements performed on 66 normal, healthy volunteers. The results of a study to ascertain the overall reproducibility of the method are provided and problems associated with the technique are discussed. Medical disorders such as atherosclerosis, diabetes mellitus, familial hypercholesterolaemia and growth hormone deficiency have all been shown to affect arterial wall compliance. It is suggested that the in vivo measurement of pressure-corrected aortic distensibility may be a useful, non-invasive tool for assessing such patients' susceptibility to atheromatous arterial disease and for monitoring their response to therapy. Measurements in the aorta may be especially pertinent since the natural history of fatty streaks there tends to parallel that in coronary arteries thereby potentially affording a convenient surrogate estimate of coronary heart disease.

Adolescent↗
PubMed1993

Aortic compliance measurements using Doppler ultrasound: in vivo biochemical correlates.

A noninvasive Doppler ultrasound technique for the assessment of aortic compliance based on the in vivo measurement of pulse wave velocity along the thoraco-abdominal aortic pathway is described. An approach for correcting for the effect of blood pressure on aortic distensibility is considered. The derivation of an index of intrinsic distensibility, Cp, which is independent of blood pressure, is provided and applied to data collected from normal, healthy volunteers. Overviews are provided of studies utilising the technique to determine aortic compliance in medical disorders, which are known to predispose to premature cardiovascular disease, such as diabetes mellitus, familial hypercholesterolaemia and growth hormone deficiency. The significance of correlations between in vivo aortic compliance measurements and plasma concentrations of total cholesterol, low-density-lipoprotein cholesterol, high-density-lipoprotein cholesterol and insulin-like growth factor-I are discussed. It is proposed that the measurement of aortic compliance in normal, healthy individuals may potentially be a useful in vivo research tool for investigating the effects of biochemical factors on the biophysical properties of the aortic wall. Furthermore, we believe that the routine measurement of blood pressure-corrected aortic distensibility may prove a useful, noninvasive clinical tool for assessing patients' susceptibility to atherosclerosis, as well as for monitoring their response to therapeutic interventions.

Adolescent↗
PubMed1993

Biochemical correlates of aortic distensibility in vivo in normal subjects.

1. Non-invasive aortic compliance measurements have been used previously to assess the distensibility of the aorta in several pathological conditions associated with increased cardiovascular risk. In adult patients with familial hypercholesterolaemia and those with growth hormone deficiency, aortic compliance has been found to correlate inversely with plasma cholesterol levels and age. We set out to establish if a relationship existed between the biophysical measurement of aortic compliance and biochemical variables in normal healthy adult subjects. 2. Blood pressure-corrected aortic distensibility, fasting insulin, insulin-like growth factor-I, total cholesterol, low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol and triacylglycerol were measured in 38 (18 males, 20 females) normotensive healthy adults. 3. Blood pressure-corrected aortic distensibility was found to correlate inversely with age (r = -0.67, P < 0.001), low-density lipoprotein-cholesterol (r = -0.37, P < 0.02) and the low-density lipoprotein-/high density lipoprotein-cholesterol ratio (r = -0.33, P < 0.05) and positively with insulin-like growth factor-I (r = 0.47, P < 0.01). On separate analysis by sex, significant inverse correlations were observed in females between aortic distensibility and total cholesterol (r = -0.50, P < 0.02), low-density lipoprotein-cholesterol (r = -0.55, P < 0.01) and age (r = -0.74, P < 0.001). A positive correlation was found between aortic distensibility and insulin-like growth factor-I (r = 0.48, P < 0.05). On forced stepwise regression analysis, however, only age (P < 0.02) was found to be significant. In males, an inverse correlation was found between aortic distensibility and age (r = -0.57, P < 0.01), low-density lipoprotein-cholesterol (r = -0.51, P < 0.05), and the low-density lipoprotein-/high-density lipoprotein-cholesterol ratio (r = -0.63, P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

A blood pressure independent index of aortic distensibility.

A non-invasive Doppler ultrasound technique for the assessment of aortic compliance based on the in vivo measurement of pulse wave velocity along the thoraco-abdominal aortic pathway is described. An approach for correcting for the effect of blood pressure on aortic compliance is considered. The derivation of an index of distensibility, Cp, which is independent of blood pressure is provided and applied to data collected from 58 normal, healthy volunteers. Medical disorders such as atherosclerosis, diabetes mellitus and familial hypercholesterolaemia have all been shown to affect arterial distensibility. We suggest that the clinical measurement of Cp may be a useful, non-invasive tool for assessing such patients' susceptibility to atheromatous arterial disease as well as for monitoring their response to therapy.

Adolescent↗
PubMed1993

An alternative approach to the semi-quantitative assessment of the transplanted renal artery velocity sonogram.

There are theoretical problems with the use of resistance based indices, i.e. pulsatility index (PI) or resistive index (RI) as stand alone measures in the renal allograft. PI and RI are heart rate dependent and input pressure dependent for autoregulating organs. A new non-invasive index, termed Pz, has been proposed. Pz may be thought of as the arterial back pressure generated by the kidney representing the pressure which needs to be overcome in perfusing the glomeruli. On a theoretical basis Pz can be shown to be independent of heart rate and resistance and to allow for variations in mean systemic blood pressure. In an initial study, a group of 53 well functioning renal allografts demonstrated a significant reduction in the coefficient of variance for Pz (12.8%) when compared to PI (25.4%). A second study on recently transplanted allografts indicated that acute tubular necrosis could not be separated from rejection on the basis of Pz. Pz did however consistently perform better than PI in terms of reduced variability within pathological groups. We conclude that Pz is more useful than PI in this application.

Blood Flow Velocity↗
PubMed1992

Non-invasive Doppler ultrasound technique for the in vivo assessment of aortic compliance.

A non-invasive Doppler ultrasound technique for the assessment of aortic compliance is described. This is based on the in vivo measurement of pulse wave velocity along the thoraco-abdominal aortic pathway. A structured protocol has been developed to improve the reproducibility of the technique as well as for the purposes of operator training. Preliminary results of a study of both the intra- and inter-observer variability of the method are provided and problems associated with the technique are discussed. Medical disorders such as atherosclerosis, diabetes mellitus and familial hypercholesterolaemia have all been shown to affect arterial wall compliance. We suggest that the measurement of aortic compliance in vivo may be a useful, non-invasive tool for assessing these patients' susceptibility to atheromatous arterial disease and for monitoring their response to therapy.

Adolescent↗
PubMed1992

Non-invasive assessment of the Circle of Willis using transcranial pulsed Doppler ultrasound with angiographic correlation.

The ability of transcranial pulsed Doppler ultrasound (TCD) to provide a dynamic assessment of the functional capability of the Circle of Willis was assessed using conventional cerebral angiography for anatomic correlation. Eleven patients had normal four-vessel cerebral angiography prior to being investigated with ultrasound. Angiography and ultrasound both demonstrated a functional anterior communicating artery in nine of the eleven patients, giving complete agreement between the two techniques. Posterior communicating arteries were visualized angiographically in all eleven patients. Ultrasound identified bilateral functional vessels in nine, the other two patients having non-functional vessels. In these latter two patients, angiography demonstrated three of the four posterior communicating arteries to be hypoplastic and it was uncertain whether these vessels carried significant blood flow. The fourth posterior communicating artery was shown to have an absent proximal segment of the ipsilateral posterior cerebral artery, with a persistent fetal posterior communicating artery. This anatomical variation is a potential limitation of ultrasound for assessing functional posterior communicating arteries. These preliminary results indicate that a combination of the anatomical (angiographic) and dynamic (ultrasonic) data may prove to be complementary for assessing the Circle of Willis.

Adult↗
PubMed1992

Aortic compliance in young patients with heterozygous familial hypercholesterolaemia.

1. Aortic compliance and plasma lipid and lipoprotein levels were measured in 20 young patients with heterozygous familial hypercholesterolaemia and in 20 age- and sex-matched control subjects. 2. Patients with familial hypercholesterolaemia had significantly higher plasma cholesterol, low-density lipoprotein-cholesterol and triacylglycerol levels than control subjects (P < 0.001, P < 0.001 and P < 0.005, respectively). The patients with familial hypercholesterolemia also had significantly more compliant (distensible) aortas than the control subjects (P < 0.001), a significant inverse correlation being observed between compliance and age (r = 0.73, P < 0.001) and between compliance and mean blood pressure (r = -0.60, P < 0.005). 3. When the effects of age and sex on aortic compliance were corrected for, the blood pressure effect disappeared, significant correlations being observed between normalized compliance and cholesterol (r = 0.50, P < 0.03), low-density lipoprotein-cholesterol (r = 0.54, P < 0.01), high-density lipoprotein-cholesterol (r = -0.44, P < 0.05), low-density lipoprotein-/high-density lipoprotein-cholesterol ratio (r = 0.60, P < 0.0006) and duration of disease (r = 0.67, P < 0.002). Multivariate regression analysis showed that the low-density lipoprotein-/high-density lipoprotein-cholesterol ratio (P < 0.03) and duration of disease (P < 0.04) were the best predictors of normalized compliance. 4. We suggest that the measurement of aortic compliance in young patients with familial hypercholesterolaemia may potentially be a useful, non-invasive, research tool for assessing their susceptibility to atheroma.

Adolescent↗