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Biomedical subjects

J D Stephens

Publications and source records attributed to J D Stephens.

46 records · Page 3Linked to original sources
PubMed1979

Prenatal genetic diagnosis in 3000 amniocenteses.

We analyzed 3000 consecutive amniocenteses for prenatal diagnosis to assess the frequency of abnormalities, safety of the procedure, technical and interpretive difficulties and overall diagnostic accuracy. Chromosomal abnormalities were detected in 2.4 per cent of the 2404 pregnancies tested because of advanced maternal age (greater than or equal to 35 years), in 1.2 per cent of 240 monitored because of prior trisomy 21 and in 9.1 per cent of 55 examined for other cytogenetic indications. Mosaicism was detected in 0.4 per cent, and unexpected translocations in 0.4 per cent. Amniotic fluid was obtained on the first attempt in 99.3 per cent of the last 1000 cases, and cultures established from 99.7 per cent of patients attending our clinic. The fluid was discolored in 1.2 per cent of patients, a quarter of whom had missed abortions. The rate of spontaneous abortion after amniocentesis was 1.5 per cent. There were 14 diagnostic errors, six serious enough to affect the outcome of pregnancy. The karyotyping error rate was 0.07 per cent. We conclude that prenatal diagnosis is safe, highly reliable and extremely accurate.

Abortion, Spontaneous↗
PubMed1979

Prenatal diagnosis of chromosomal abnormalities and neural tube defects.

We have reviewed the current status of prenatal diagnosis for chromosomal indications and for neural tube defects. The number of pregnancies monitored will increase as greater resources become available and as public education about genetics increases. The methodology has proved to be a powerful means of preventing the birth of individuals with significant genetic defects, thereby sparing both parents and society from the burdens produced by such disorders. In the future, it is likely to be even more effective.

Amniocentesis↗
PubMed1978

Verification of human fetal breathing with phased array ultrasound imaging.

Continuous observation of fetal movement patterns is a novel and useful capability of new high-speed ultrasound imaging systems. Confirmatory documentation of human fetal breathing as a component of these movement patterns has been achieved using a phased-array real time ultrasound sector scanning system. This system permits direct visualization of fetal breathing movements. Permanent recordings can be made on videotape. Recordings can also be made as a time-motion echocardiograms during continuous observation of the full sector. Fetal breathing movements were seen in five patients. The earliest period of gestation at which fetal breathing was seen was 20 weeks.

Animals↗
PubMed1978

Comparative peripheral and coronary haemodynamic effects of rimiterol and isoprenaline.

1. Rimiterol and isoprenaline produced significant dose-related increases in cardiac output. 2. These changes in cardiac output were accompanied by increases in heart rate and myocardial oxygen consumption which were similar for each drug and dose-related. 3. Isoprenaline in contrast with rimiterol produced direct coronary vasodilation, i.e. coronary vasodilation in excess of that required to meet increases in myocardial oxygen demands. 4. It is suggested that the beta-adrenergic receptors in the human coronary vasculature are mainly of the beta1 type. 5. Rimiterol, because it does not produce direct coronary vasodilation may be preferable to isoprenaline in the treatment of low-cardiac output syndrome where there is regional myocardial ischaemia, since it would be less likely to produce a "coronary steal" effect.

Adult↗
PubMed1978

Haemodynamic effects of isosorbide dinitrate in patients with congestive cardiac failure at rest and during submaximal supine exercise.

Eight patients with chronic congestive cardiac failure secondary to ischaemic heart disease performed submaximal supine exercise before and after 5 mg sublingual isosorbide dinitrate (ISDN) at the time of cardiac catheterisation. Exercise before ISDN produced a poor response in left ventricular performance. After ISDN this response was significantly improved. Compared with the control exercise period cardiac index (CI) increased from mean 2.9 to 3.5 l/mn/m2 (p = less than 0.0025), stroke volume index (SVI) from mean 24 to 29 ml/m2 (p = less than 0.0005) and left ventricular stroke work index (LVSWI) from mean 22 to 28 g-m/m2 (p = less than 0.0025). Although ISDN reduced LVEDP significantly at rest, there were associated small but significant falls in CI, SVI and LVSWI. The improvement in exercise cardiac index was related to the ejection fraction, or the ejection fraction of the contractile section where a left ventricular aneurysm was present. ISDN may be effective in improving exercise tolerance in ambulant patients with chronic congestive cardiac failure.

Administration, Oral↗