AE Aquarii: A Short Review

The nova-like variable AE Aquarii has been continuously studied since its discovery on photographic plates in 1934. In this short review the peculiar multi-wavelength properties of AE Aquarii will be reviewed and explained in context of its evolution from a high mass transfer phase, during which period it could have been a supersoft X-ray source (SSS)

Insights into the pathogenesis of viral haemorrhagic fever based on virus tropism and tissue lesions of natural Rift Valley fever

Rift Valley fever phlebovirus (RVFV) infects humans and a wide range of ungulates and historically has caused devastating epidemics in Africa and the Arabian Peninsula. Lesions of naturally infected cases of Rift Valley fever (RVF) have only been described in detail in sheep with a few reports concerning cattle and humans. The most frequently observed lesion in both ruminants and humans is randomly distributed necrosis, particularly in the liver. Lesions supportive of vascular endothelial injury are also present and include mild hydropericardium, hydrothorax and ascites; marked pulmonary congestion and oedema; lymph node congestion and oedema; and haemorrhages in many tissues. Although a complete understanding of RVF pathogenesis is still lacking, antigen-presenting cells in the skin are likely the early targets of the virus. Following suppression of type I IFN production and necrosis of dermal cells, RVFV spreads systemically, resulting in infection and necrosis of other cells in a variety of organs. Failure of both the innate and adaptive immune responses to control infection is exacerbated by apoptosis of lymphocytes. An excessive proinflammatory cytokine and chemokine response leads to microcirculatory dysfunction. Additionally, impairment of the coagulation system results in widespread haemorrhages. Fatal outcomes result from multiorgan failure, oedema in many organs (including the lungs and brain), hypotension, and circulatory shock. Here, we summarize current understanding of RVF cellular tropism as informed by lesions caused by natural infections. We specifically examine how extant knowledge informs current understanding regarding pathogenesis of the haemorrhagic fever form of RVF, identifying opportunities for future research

The use of Doppler velocitnetry of the utnbilical artery before 24 weeks' gestation to screen for high-risk pregnancies

Objective. To describe the prevalence and natural history of absent end-diastolic velocities (AEDV) in the mnbilical artery of the fetus between 16 and 24 weeks' gestation, and to evaluate its role as a screening test.Design. Population-based descriptive study.Setting. Tygerberg Hospital, Tygerberg, South Africa. The hospital serves a population from the lower socio-economic bracket.Subjects. Doppler velocimetry was performed at routine ultrasound examinations for confirmation of gestational age in 496 women.Main outcome measures. The occurrence of perinatal death, small-for-gestational-age (SGA) babies and proteinuric hypertension.Results. Forty-four (8,9%) patients had AEDVs at the first examination, but AEDV persisted in only 1. In this case, severe proteinuric hypertension developed unexpectedly at 29 weeks' gestation and the fetus needed delivery because ofpersistent late decelerations of the fetal heart rate pattern. There was a significant association between the group with AEDV at first examination and the development of proteinuric hypertension (P <0,05), but no association with SGA babies. The association with proteinuric hypertension was too weak to be of clinical use.Conclusion. Doppler velocimetry of the mnbilical artery, performed along with routine ultrasound examination to confirm gestational age, is not of use as a screening test for identifYing highrisk pregnancies

Spontaneous prolonged contractions during antenatal fetal heart rate monitoring

CITATION: Reinhardt, G., Odendaal, H.J. & Kotze, T.J.v.W. 1987. Spontaneous prolonged contractions during antenatal fetal heart rate monitoring . S Afr Med J, 71(1):17-19.The original publication is available at http://www.samj.org.zaENGLISH ABSTRACT: Uterine contractions of more than 2 minutes' duration occurred spontaneously in 1.4% of 6399 antenatal fetal heart rate (FHR) recordings. All recordings were made in the Department of Obstetrics and Gynecology at Tygerberg Hospital. The patients with spontaneous prolonged contractions (SPC) were compared with a randomly selected control group. Patients who had an SPC during antenatal FHR recording were not at a higher risk of abruptio placentae, preterm labour or unexpected intra-uterine death. Of the infants born to the mothers in the study group, 65.5% were male. There were more primigravidas in the study group, which may have been responsible for the longer duration of the second stage of labour in this group. When primigravidas only were examined no difference between the two groups could be found except for a larger placental mass in the study group. It is uncertain why primigravidas were more likely to develop SPCs as observed during antenatal FHR monitoring.Publisher’s versio

Umbilical artery Doppler velocimetry in the prediction of intrapartum fetal compromise

CITATION: Howarth, G. R. et al. 1992. Umbilical artery Doppler velocimetry in the prediction of intrapartum fetal compromise. South African Medical Journal, 81:248-250.The original publication is available at http://www.samj.org.zaThe value of early intrapartum umbilical artery Doppler velocimetry in the prediction of fetal compromise was studied. One hundred patients were recruited into the study and fetal compromise was diagnosed by abnormal first- or second-stage fetal heart rate traces, a 5-minute Apgar score less than 7, or the development of hypoxic ischaemic encephalopathy. Fetal compromise developed in 30 patients. An umbilical artery resistance index (RI) of 0,66 or less did not predict fetal compromise (sensitivity 13%, specificity 89%, positive predictive value 25%, negative predictive value 70%). Since the mean umbilical artery RI was identical in the compromised and the noncompromised groups, we conclude that early intrapartum Doppler velocimetry is of very little clinical value in predicting fetal compromise at term.Publisher’s versio

Increased placental resistance and late decelerations associated with severe proteinuric hypertension predicts poor fetal outcome

CITATION: Pattinson, R. C. et al. 1989. Increased placental resistance and late decelerations associated with severe proteinuric hypertension predicts poor fetal outcome. South African Medical Journal, 75:211-214.The original publication is available at http://www.samj.org.zaThe flow velocity wave forms generated by Doppler ultrasound examination of the umbilical artery were correlated with feto-placental blood flow and numerically expressed as a ratio between the systolic (A) and the end-diastolic point (B). The technique is non-invasive and simple to perform. A cohort analytical study was done to see whether useful information could be obtained from the A/B ratio that could help in the management of patients with severe proteinuric hypertension. Fifty patients with severe proteinuric hypertension at less than 34 weeks' gestation were studied and serial Doppler ultrasound examinations of the umbilical artery were performed. No ultrasound results were made available to the clinician. An A/B ratio of 6 or greater was regarded as increased. Twenty-eight of the patients had an increased A/B ratio; in this group these 14 infants were small for gestational age, 14 developed late decelerations and there were 12 perinatal deaths. The remaining 22 patients had an A/B ratio of less than 6 and only 3 produced infants which were small for gestational age; 2 fetuses developed late decelerations and there was 1 perinatal death. A significant difference was found between the two groups in respect of these results. The group with an abnormal A/B ratio also experienced more neonatal morbidity. The A/B ratio of the umbilical artery wave form may assist in planning delivery of patients with severe proteinuric hypertension more accurately.Publisher’s versio