PubMed Health⌕ Search

Biomedical subjects

R F Lamont

Publications and source records attributed to R F Lamont.

49 records · Page 3Linked to original sources
PubMed1990

Production of prostaglandin E2 by human amnion in vitro in response to addition of media conditioned by microorganisms associated with chorioamnionitis and preterm labor.

To examine the potential role of bacterial infection in the cause of spontaneous preterm labor, human amnion cells in tissue culture were exposed to medium conditioned by culturing each of 21 microorganisms previously found in association with chorioamnionitis and preterm labor. At a final concentration of 0.1% bacterial conditioned medium, a significant stimulation of prostaglandin E2 production from amnion cells was observed for this range of microorganisms. Conditioned medium obtained from culturing Bacteroides fragilis caused a dose-related increase in prostaglandin production, final concentrations of 0.02% to 0.1% being stimulatory but greater concentrations (0.1% to 10%) causing a progressive inhibition of prostaglandin synthesis. A similar concentration-related response in which stimulation was followed by inhibition occurred on addition of increasing concentrations of phospholipase A2 to amnion cells. These data suggest that bacterial phospholipase may release arachidonic acid from amnion leading to prostaglandin E2 synthesis, but excessive addition of phospholipase and consequent increased arachidonic acid availability may give rise to substrate inhibition of cyclooxygenase enzyme and inhibit prostaglandin E2 synthesis. Overall it appears that a wide variety of microorganisms associated with preterm labor may secrete phospholipase, which liberates amnion arachidonic acid for conversion to the oxytocic agent prostaglandin E2.

Amnion↗
PubMed1989

Continuous versus intermittent epidural analgesia. A randomised trial to observe obstetric outcome.

A randomised study of 381 women was carried out to compare the obstetric outcome after epidural analgesia maintained by an intermittent top-up regimen or with a continuous infusion. The two groups were well matched with respect to age, parity, mode of onset of labour and indication for epidural. Maintenance of epidural analgesia by continuous infusion resulted in a significantly decreased need for top-up doses. A reduction in the incidence of hypotension, cardiotocographic evidence of intrapartum fetal hypoxia and Caesarean section was associated with this. It is concluded that the maintenance of epidural analgesia by continuous infusion is a safe and reliable method and may be more advantageous and less labour intensive than the traditional intermittent regimen.

Analgesia, Epidural↗
PubMed1987

The role of mycoplasmas, ureaplasmas and chlamydiae in the genital tract of women presenting in spontaneous early preterm labour.

The genital carriage of Ureaplasma urealyticum, Mycoplasma hominis and Chlamydia trachomatis was assessed in 72 women admitted to hospital in spontaneous preterm labour and in 26 women requiring preterm delivery for other reasons who formed a control group. Women in preterm labour significantly more often carried ureaplasmas, had large numbers of M. hominis and subsequently developed chorioamnionitis than women in the control group. M. hominis, in particular, occurred more frequently and in large numbers in women who had chorioamnionitis associated with ruptured membranes. Genital carriage of the various micro-organisms appeared not to be associated with fetal growth retardation, although subsequent isolation of ureaplasmas from infants was common. It is suggested that mid-second-trimester vaginal specimens should be cultured on a research basis to establish whether these various micro-organisms identify women at risk of labouring preterm.

Birth Weight↗
PubMed1986

Spontaneous early preterm labour associated with abnormal genital bacterial colonization.

The association between infection and preterm labour was studied in 72 women in spontaneous preterm labour between 26 and 34 weeks gestation and in 26 control subjects having an elective caesarean section at the same gestational age. The genital microbial flora of each group was studied comprehensively and included mycoplasmas, chlamydiae, ureaplasmas and anaerobes. Subsequent neonatal infection and chorioamnionitis was also studied. Abnormal bacterial colonization, the presence of ureaplasmas, heavy growth of mycoplasmas and chorioamnionitis were all found significantly more often in the study group. This supports the premise that a significant proportion of idiopathic preterm labour is associated with infection and this may permit better prediction and prevention of preterm birth. The continued use of tocolytics should depend upon the identification of the presence or absence of infection. Infection appeared to be the result rather than the cause of ruptured membranes. A recommendation with respect to the classification of abnormal or normal bacterial colonization between 26 and 34 weeks is suggested on the basis of strict criteria.

Bacteria↗
PubMed1986

The management of preterm labour.

Preterm labour is a major cause of perinatal mortality and morbidity. The aetiology is multifactorial and attempts to predict preterm labour are unsuccessful. At the present time prophylaxis is unhelpful and the obstetrician must manage preterm labour as it arises. The management of preterm labour remains controversial because of the difficulty in conducting good clinical trials. Antepartum glucocorticoids are effective in reducing the incidence and severity of respiratory distress syndrome. The effect is dependent upon a number of factors such as race, fetal sex, gestational age, state of the membranes, fetal asphyxia and timing of delivery in relation to therapy. Tocolytics are effective in stopping contractions but this does not produce a significant prolongation of pregnancy or reduce perinatal mortality or morbidity. It is because they can suppress contractions and delay delivery for a short time that great care should be taken that this short delay is used beneficially, e.g. in-utero transfer, or steroid therapy. It is also important that this suppression does not result in an inappropriate delay where early delivery is indicated because of infection or fetal distress. Steroids, tocolytics and antibiotics are potentially hazardous although all may benefit the fetus. The particular risks versus benefits of each form of therapy should be carefully considered for the particular presentation of each individual patient. While all these agents given antenatally are of potential benefit to the fetus and neonate, prolongation of pregnancy for its own sake or for the sake of allowing time to administer such agents is no substitute for delivery of an infant in optimum condition.

Adrenergic beta-Agonists↗
PubMed1985

Effect of bacterial products on prostaglandin E production by amnion cells.

An in-vitro model was set up to study a possible causal relation between bacterial colonisation of extraplacental membranes and spontaneous preterm labour. When amnion cells in tissue culture were exposed to bacterial products, their prostaglandin E output rose considerably. The degree of response varied with the organism. These findings support the theory that bacterial products may be responsible for the premature onset of labour.

Amnion↗
PubMed1983

Spontaneous preterm labour and delivery at under 34 weeks' gestation.

The management and outcome of 242 infants delivered between 26 and 34 weeks' gestation in an obstetrical and neonatal regional referral centre as a result of spontaneous preterm labour were recorded prospectively. Results of the survey show that the decision to intervene and delay delivery will depend on the availability of neonatal intensive care facilities. Infants likely to require intensive neonatal care should be transferred in utero to a centre with these facilities. The use of steroids reduces the mortality of preterm infants. The maximum effect occurs between 30 and 32 weeks' gestation, and there is no benefit after 34 weeks. If the weight is over 1500 g the mode of delivery of the preterm infant presenting by the breech does not influence outcome; if under 1500 g a caesarean section improves survival over those infants born by vaginal breech delivery.

Birth Weight↗
PubMed1983

Use of glucocorticoids in pregnancies complicated by severe hypertension and proteinuria.

During a 2-year period, 56 infants of less than 34 weeks gestation were delivered from 53 pregnancies complicated by severe hypertension and proteinuria. In the first part of the study 32 infants were delivered whose mothers did not receive antepartum glucocorticoids; subsequently 24 infants were born whose mothers did receive antepartum glucocorticoids. The severity of maternal disease, gestational age at delivery, birthweight and obstetric management was similar in both groups. In the group receiving glucocorticoids 88% of the infants were discharged live from the neonatal unit compared with 72% in the group who did not receive corticosteroids. It is concluded that in pregnancies complicated by severe hypertension and proteinuria requiring delivery before 34 completed weeks of pregnancy, the administration of antepartum glucocorticoids to the mother does not carry an increased risk to the fetus, and may be of benefit by reducing the risk of idiopathic respiratory distress syndrome and subsequent intraventricular haemorrhage.

Adult↗
PubMed1983

Comparative mortality and morbidity of infants transferred in utero or postnatally.

The outcome of two hundred and twelve infants transferred in utero and delivered in the regional neonatal intensive care center is compared with one hundred and sixty-six infants born elsewhere and transferred neonatally to the same unit, during the same period of time. The mean birthweight (+/- 1 S.D.) was 1391 g (+/- 415 g) for the infants transferred in utero, and 1398 g (+/- 415 g) for the infants transferred neonatally. The mean gestational age of the two groups was 29.9 completed weeks for both groups. Survival was defined as discharge from the neonatal unit and intraventricular hemorrhage was diagnosed ultrasonically. The survival rate was 83% for the group transferred in utero and 70% for the group transferred postnatally (p = less than 0.01). The incidence of intraventricular hemorrhage was 30% and 45% respectively (p = less than 0.01). Using birthweight specific perinatal mortality rates and intraventricular hemorrhage rates of the neonatally transferred group for standardisation, it can be calculated that 27 infants survived and 31 were protected from intraventricular hemorrhage because of in utero transfer. It is concluded that infants likely to require neonatal intensive care have decreased mortality and morbidity if transferred in utero to a center with these facilities rather than being transferred neonatally.

Cerebral Hemorrhage↗
PubMed1982

Risk factors in the development of intraventricular haemorrhage in the preterm neonate.

One hundred and forty-six infants of 34 weeks' gestation or less were repeatedly scanned by means of real-time ultrasound to diagnose the presence of intraventricular haemorrhage (IVH), its severity, and the timing of onset of the condition. We describe a new method for grading the extent of the IVH which does not depend on ventricular size. IVH was clearly present in 52 (36%) of the 146 infants and in 32 (50%) of the 64 infants of 30 weeks' gestation or less. Repeated scans accurately timed the onset of IVH in 41 infants, and 32 (78%) had the first sign of IVH before 72 hours of age. Thirty-two clinical factors were analysed for possible correlation with the development of IVH: outborn compared with inborn, administration of sodium bicarbonate, hypothermia, intermittent positive pressure ventilation, continuous positive airways pressure, hypercapnia, severe acidosis, and respiratory distress syndrome all reached statistical significance. Analysis of variance showed that respiratory distress syndrome was the most important factor, but severe acidosis had some independent action on the development of IVH. Seventeen (81%) of 21 infants with hypercapnia (PCO2 greater than 6 kPa) together with severe acidosis (pH less than 7.1) developed IVH, of which more than half was moderate or severe in degree.

Acidosis↗