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Biomedical subjects

S A Steel

Publications and source records attributed to S A Steel.

34 records · Page 2Linked to original sources
PubMed1994

Dipyridamole is superior to dobutamine for thallium stress imaging: a randomised crossover study.

OBJECTIVE: To assess the value of dobutamine over dipyridamole as a pharmacological stressing agent in myocardial perfusion imaging with thallium-201. DESIGN: Stress and redistribution tomographic images were taken in a group of patients in a randomised crossover study of both agents. The scans were scored to give a value for the stress and redistribution images and a reversibility score (redistribution--stress). All patients had coronary angiography that was also scored. Differences between the two agents were compared by a paired t test. PATIENTS: 30 patients aged 51-70 years with chest pain thought to be caused by myocardial ischaemia. 11 had had previously myocardial infarction. RESULTS: Dipyridamole caused adverse symptoms in six patients whereas dobutamine caused symptoms in 21 patients (chi 2 = 15.15, p < 0.0001). Dobutamine stress took considerably longer than dipyridamole (31 v 6 minutes) and cost more (17 pounds v 1.50 pounds). There were no significant differences between the agents in terms of total stress or redistribution scores, but regional analysis showed that dipyridamole showed significantly more defects during stress at the apex and lateral wall (p < 0.05), with no significant difference at redistribution. Dipyridamole stress also caused significantly more reversible defects at the apex (p < 0.05) and gave a better correlation than dobutamine with coronary score (dipyridamole r = 0.80, p < 0.001 v dobutamine r = 0.64, p < 0.001). In six patients who had continued to take beta blockers the results of dobutamine stress did not correlate with coronary score, r = 0.34 (NS), whereas dipyridamole studies were not affected. CONCLUSION: Compared with dobutamine, dipyridamole was as effective in producing overall perfusion defects and more effective in provoking defects at the apex and lateral segment. The dipyridamole study correlated better with coronary score and was not affected by concurrent beta blocker treatment. It was also better tolerated by the patients, was less time consuming, and was much cheaper.

Aged↗
PubMed1994

The effects of daily wear contact lenses on goblet cell density.

BACKGROUND: Some patients can wear contact lenses with a low tear breakup time while others with an identical tear breakup time cannot wear lenses. This suggests the current method of tear film assessment is inadequate at differentiating between these two types of patients. The study attempts to expand our knowledge of the tear film with special attention directed to a critical yet little studied component: mucin. Mucin is vital to maintenance of the tear film and functions as a tear film stabilizer. The condition of the precorneal tear film is a major determinant in the success of contact lens wear. METHODS: Eighteen subjects free of ocular surface disease who had never worn contact lenses had the goblet cell density of their inferior bulbar conjunctiva determined by impression cytology. The subjects were then fit in a 38 percent water polymacon lens and their goblet cell density determined on a monthly basis for 6 months. RESULTS: Nearly a 2-fold increase in goblet cell density was observed in 88 percent of the subjects over the 6-month period. The first statistically significant increase occurred 5 months after the initiation of lens wear when the goblet cell density rose from 4.19-7.84 percent. CONCLUSIONS: We speculate the increase in goblet cells is an adaptive response of the ocular surface to a coated daily wear contact lens.

Adolescent↗
PubMed1993

Influence of birth weight on adult bone mineral density.

Bone mineral density (BMD) increases during growth until a peak is reached at maturity. The risk of development of postmenopausal osteoporosis depends on the peak bone density and the rate of its subsequent loss. To identify whether low weight at birth could affect the peak bone density, we measured BMD at both the lumbar spine and femoral neck using dual energy X-ray absorptiometry (DXA) in a group of women who had low weight at birth and in a control group of normal birth weight. There was no significant correlation between the weight at birth and the adult BMD. It appears, therefore, that low weight at birth does not influence the peak bone density and that prematurity is not a risk factor for osteoporosis.

Adult↗
PubMed1992

The relation between bone mineral density and early pregnancy loss.

OBJECTIVE: To determine if women who suffer from early pregnancy loss are at increased risk of osteoporosis later in life. DESIGN: Part of a community screening project for bone mineral density (BMD). SUBJECTS: 392 women aged 50-54 who had had from 0 to 6 miscarriages out of 0 to 8 term pregnancies. TECHNIQUE: BMD measured using dual energy X-ray absorptiometry at both the lumbar spine and the proximal femur. RESULTS: The mean BMD in nulligravid women was not significantly different from those whose only pregnancies ended in early loss. There was no significant correlation between the BMD at either the lumbar spine or the proximal femur and the number of miscarriages (r = 0.03 and 0.01, respectively). The BMD of the lumbar spine and femoral neck were not affected by parity (P = 0.08 and P = 0.87, respectively). CONCLUSION: The risk of osteoporosis was not influenced by parity or the number of previous miscarriages.

Abortion, Spontaneous↗
PubMed1991

[Correlation between the results of Doppler velocimetry with spectral analysis and the viscosity of cord blood].

The contribution of rheological factors to be impedance of blood flow in the umbilical artery as determined by continuous wave Doppler ultrasound was investigated. Of the 51 pregnancies recruited, six were complicated by pre-eclampsia, 10 by intrauterine growth retardation, 15 by both pre-eclampsia and fetal growth retardation, and there were 20 controls. A significant correlation was demonstrated between both plasma viscosity and gestational age and the resistance index used to characterize the Doppler waveform. Multiple regression analysis demonstrated that changes in plasma viscosity explained 55 p. cent of the variance seen in the resistance index and that this was statistically significant. This finding is, however, unlikely to be of clinical significance as whole blood viscosity had an insignificant effect on the impedance in the umbilical artery. We postulate that vascular factors such as the number and calibre of the placenta arterioles are a more important determinant of umbilical artery impedance.

Blood Flow Velocity↗
PubMed1991

Modification of impression cytology for in-office use.

An in-office procedure for assessment of the conjunctival epithelium, goblet cells, mucin and immune cells is described. The collection of three samples from each eye greatly improves cell harvest and increases reproducibility of the technique called impression cytology. The protocol and its pitfalls are discussed as well as the numerous applications of impression cytology.

Biopsy↗
PubMed1990

Early Doppler ultrasound screening in prediction of hypertensive disorders of pregnancy.

1198 nulliparous women were screened in early pregnancy (median 18 weeks' gestation) by the recording of doppler ultrasound waveforms from the uteroplacental circulation. After exclusions, the results of 1014 women were available for analysis; 118 (12%) of them had persistently abnormal waveforms on repeat ultrasound scans at 24 weeks and were taken to have a positive test result. Hypertension was significantly more frequent among those women than among women with normal doppler waveforms (29/118 [25%] vs 45/896 [5%]). In addition, hypertension in women with abnormal waveforms was more likely to be severe; 12 (10%) had proteinuria and 15 (13%) intrauterine growth retardation compared with 7 (0.8%) and 0, respectively, of those with normal waveforms. Overall, the test did poorly when assessed by standard statistical means. However, the sensitivity was high for hypertension associated with either proteinuria (63%) or intrauterine growth retardation (100%). The test is cheap, easy to carry out, and non-invasive, and it can be done in early pregnancy; it is therefore a useful means of identifying a high-risk group of pregnant women suitable for therapeutic intervention to reduce the incidence of hypertensive disorders and their complications.

Adult↗
PubMed1989

Correlation between Doppler flow velocity waveforms and cord blood viscosity.

The contribution of rheological factors to the impedance of blood flow in the umbilical artery as determined by continuous-wave Doppler ultrasound was investigated. Of the 51 pregnancies recruited, six were complicated by pre-eclampsia, 10 by intrauterine growth retardation, 15 by both pre-eclampsia and fetal growth retardation, and there were 20 controls. A significant correlation was demonstrated between both plasma viscosity and gestational age and the resistance index used to characterize the Doppler waveform. Multiple regression analysis demonstrated that changes in plasma viscosity explained 55% of the variance seen in the resistance index and that this was statistically significant. This finding is, however, unlikely to be of clinical significance as whole blood viscosity had an insignificant effect on the impedance in the umbilical artery. We postulate that vascular factors such as the number and calibre of the placental arterioles are a more important determinant of umbilical artery impedance.

Blood Flow Velocity↗
PubMed1988

Doppler ultrasound of the uteroplacental circulation as a screening test for severe pre-eclampsia with intra-uterine growth retardation.

Two hundred primiparae underwent continuous-wave Doppler investigation of the uteroplacental circulation at 18-20 weeks gestation as a possible screening test for hypertension in pregnancy. Seventy-five women with abnormal waveforms suggestive of high uteroplacental resistance were tested again at 24 weeks when 21 demonstrated a persistent abnormality. Only nine (43%) of these went on to have an uncomplicated pregnancy, as compared with 150 (84%) of the remainder. Seventeen (8.5%) of the women in the study developed a hypertensive disorder of pregnancy, five of whom had abnormal waveforms at 18-20 weeks and at 24 weeks. These five women had a more severe degree of hypertension with proteinuria or intra-uterine growth retardation, and two required clinical intervention before term. The remaining 12 women were delivered at term of average, or heavier than average babies. Doppler investigation of the uteroplacental circulation at 24 weeks may prove to be a sensitive screening test for later severe pre-eclampsia with intra-uterine growth retardation.

Adult↗
PubMed1988

Maternal blood viscosity and uteroplacental blood flow velocity waveforms in normal and complicated pregnancies.

According to the Poiseuille-Hagen law, viscosity influences flow resistance. A possible effect of blood viscosity upon the resistance index of the uteroplacental circulation as measured by continuous wave Doppler ultrasound was investigated in 50 pregnant women. It was found that blood viscosity variables explained only about 10% of the variation in the resistance index in all patients, which was not statistically significant. It is suggested, therefore, that the vascular contribution to flow resistance may be more important.

Blood Flow Velocity↗
PubMed1988

Specific therapy in severe fetal intrauterine growth retardation: failure of prostacyclin.

Two case histories of severe, early onset intrauterine growth retardation are presented. Intravenous prostacyclin was administered in an attempt to promote fetal growth and thus prolong the pregnancy, but was unsuccessful and resulted in intrauterine death in each case. The possible reasons for the failure of this treatment and alternative therapeutic options are discussed.

Adult↗
PubMed1986

Long-term follow-up of detrusor instability following the colposuspension operation.

Pre- and post-operative clinical and urodynamic data have been reviewed in 24 women with detrusor instability following colposuspension. Follow-up ranged from 3 to 5 years. Ten women remained asymptomatic throughout; of the remainder, four (28.6%) were improved by drug therapy. With one exception, patients who were symptomatic at the outset remained so at late follow-up.

Adult↗
PubMed1986

Delivery of the very low birthweight baby.

The outlook for the baby weighing less than 1500 g at birth has dramatically improved over the last decade largely due to advances in neonatal intensive care. This, however, has created new clinical dilemmas in obstetric management and delivery. This article provides a critical review of published work, highlights the questions that remain unanswered and suggests guidelines for clinical management in the light of current knowledge.

Anesthesia, Obstetrical↗