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Biomedical subjects

Ronald F Lamont

Publications and source records attributed to Ronald F Lamont.

13 recordsLinked to original sources
PubMed2005

The measurement of dendritic cells in umbilical cord blood: a novel technique using small volumes of whole blood.

OBJECTIVE: To develop a technique that would permit the identification of dendritic cells (DC) in small volumes of preterm neonatal cord blood in order to investigate neonatal immune response in relation to infection and preterm labor. METHODS: We used three-color flow cytometry and a fixed quantity of fluorospheres to determine absolute cell numbers. Four red cell lysis techniques, sample dilution, time delay experiments, and a comparison with traditional Ficoll cell separation techniques were performed. Absolute numbers of DC recovered using each technique were calculated and compared. RESULTS: With increasing time delay, there was a statistically significant reduction in the numbers of leukocytes in adult blood. In contrast, there was a significant increase in leukocytes in umbilical cord blood. Sample dilution did not significantly affect the total number of leukocytes or DC. The use of the reagent Optilyse B (Immunotech, Oxford, UK) combined with an additional washing step produced the best discrimination of all populations based on light scatter properties. For the same blood sample, antibody labeling of whole blood resulted in a greater recovery of DC when compared to prior cell purification using a Ficoll density gradient. CONCLUSION: Using traditional Ficoll cell separation, cell manipulation requires large volumes of blood and leads to cell loss and alteration in phenotype. We have validated a novel method using small volumes of whole blood, diluted if necessary, and using red cell lysis to enable analysis of small volumes of preterm neonatal cord blood. This may permit further analysis of the contribution of the fetal immune response in the development of spontaneous preterm labor and preterm birth due to infection.

Adult↗
PubMed2004

Are reported preterm birth rates reliable? An analysis of interhospital differences in the calculation of the weeks of gestation at delivery and preterm birth rate.

We investigated the possibility of preterm birth misclassification as a determinant of variation in its reported rates. Using a database of 497,105 deliveries from 17 hospitals, the best estimate of gestational age made at delivery and entered into the database at that time was recalculated from the menstrual dates and mid-trimester ultrasound scan. The recalculated completed weeks of gestation at delivery was compared with that made at birth. Calculation of estimated gestational age varied between hospitals due to inconsistencies in 'rounding' and 'truncating' the weeks of gestation at delivery. This resulted in preterm birth misclassification rates of up to 10.1%.

Birth Rate↗
PubMed2003

Intravaginal clindamycin to reduce preterm birth in women with abnormal genital tract flora.

OBJECTIVE: To assess the ability of clindamycin vaginal cream to reduce the incidence of preterm birth in women with abnormal genital tract flora in the second trimester of pregnancy. METHODS: This was a randomized, double-blind, placebo-controlled, tricenter study. A total of 409 women with abnormal genital tract flora on Gram stain of vaginal secretions at 13-20 weeks' gestation were randomized to receive a 3-day course of clindamycin vaginal cream or placebo. Those women who still had abnormal vaginal flora 3 weeks later received a 7-day course of the original study drug (ie, either clindamycin vaginal cream or placebo as per original randomization). The primary outcome measure was the incidence of preterm birth. RESULTS: There was a statistically significant reduction in the incidence of preterm birth in the clindamycin vaginal cream group (4%) compared with placebo (10%) (P <.03). Significantly more babies born preterm (63%) required admission to the neonatal intensive care unit compared with term infants (4%) (P <.001). CONCLUSION: A 2% clindamycin vaginal cream, when compared with placebo administered to women with abnormal genital tract flora before 20 weeks' gestation, can reduce the incidence of preterm birth by 60% and hence the need for neonatal intensive care.

Administration, Intravaginal↗
PubMed2003

Infection in the prediction and antibiotics in the prevention of spontaneous preterm labour and preterm birth.

The association between infection and spontaneous preterm labour is now well established and thought to be responsible for preterm birth in up to 40% of cases. Preterm labour that is due to infection is refractory to the use of tocolytic agents. So the knowledge that infection may be the cause is unhelpful once a woman is admitted in spontaneous preterm labour, since by that time there may be irreversible changes in the uterine cervix, which renders futile those attempts to inhibit the process. It would be much more logical to use the association between infection and spontaneous preterm labour to identify a group of women at risk and to intervene using antibiotic prophylaxis. It is important to record, that the earlier in gestation at which abnormal genital tract colonisation is detected, the greater is the risk of an adverse outcome. For example, abnormal genital tract flora at 26-32 weeks gestation is associated with preterm birth with an odds ratio (OR) of 1.4 to 2, whereas abnormal genital tract flora at 7-16 weeks gestation carries an OR of 5 to 7.5. Intervention studies have used different antibiotics in different dosage regimes by different routes of administration to patients of differing risks at different gestational ages. Not surprisingly this has led to differing results. If intervention is to be successful, the antibiotics chosen should be active against bacterial vaginosis or bacterial vaginosis-related organisms and should be used early in pregnancy in those women with the greatest degree of abnormal genital tract flora. While there is logic in using intravaginal antibiotics to deliver a heavy antibiotic load to the vagina where heavy abnormal colonisation exists, there is also logic in considering systemic antibiotics to eradicate those organisms, which have already gained access to the decidua. It may be that the greatest chance of benefit would exist if both routes of administration were combined. Yet no study has evaluated the combination of both intravaginal and systemic antibiotics to eradicate abnormal genital tract flora for the prevention of preterm birth.

Antibiotic Prophylaxis↗
PubMed2003

An update on the controversies of tocolytic therapy for the prevention of preterm birth.

Preterm birth is the major cause of perinatal mortality and morbidity in the developed world. Where there are no contraindications to their use, tocolytics can improve neonatal survival rates by approximately 3% per day between 23 and 27 weeks gestation with a concomitant reduction in morbidity. The ultimate aim of tocolytic therapy is to prolong pregnancy until growth and maturation is complete, but even short-term delay may enable the administration of antepartum glucocorticoids to reduce hyaline membrane disease or to arrange transfer to a center with neonatal intensive care facilities. Both of these have been shown to reduce neonatal mortality and morbidity. Until recently, none of the currently used tocolytics, whether licensed or unlicensed, were developed specifically for the inhibition of preterm labor and consequently, they exhibit various potentially serious side-effects. As a result of the recent licensing of the oxytocin antagonist, atosiban, developed for the treatment of preterm labor and due to its high utero-specificity, obstetricians have experienced an advance in their options for the management of spontaneous preterm labor.

Adrenergic beta-Agonists↗
PubMed2003

The efficacy of vaginal clindamycin for the treatment of abnormal genital tract flora in pregnancy.

OBJECTIVE: To assess the efficacy of 2% clindamycin vaginal cream (CVC) to treat bacterial vaginosis (BV) in pregnancy. METHODS: A prospective, randomized, double-blind, placebo-controlled, tricenter study. Four hundred and four women with BV on Gram stain at their first antenatal clinic visit were randomized to receive a 3-day course of 2% CVC or placebo. The outcome was assessed using an intention to treat analysis at 3 weeks and 6 weeks post-treatment according to three different diagnostic methods based on five criteria (Gram stain and all four elements of clinical composite criteria: vaginal discharge, abnormal vaginal pH, clue cells, amine odor), three criteria (vaginal pH, clue cells, amine odor) or two criteria (clue cells and amine odor) to reflect stringency of diagnosis, historical precedence and government agency recommendations respectively. RESULTS: Using five diagnostic criteria, 18% of CVC patients were cured and 70.8% either cured and/or improved compared to 1.6% and 12% of placebo patients respectively (p < 0.0001). Using three diagnostic criteria, 44.8% of CVC patients were cured and 77.3% were either cured and/or improved compared to 9.3% and 28.8% of placebo patients respectively (p < 0.000 1). Using two diagnostic criteria, 75.0% of CVC patients were cured compared to 18.0% of placebo patients (p < 0.0001 ). Recurrence rates in those CVC patients successfully treated were approximately 6% at 6 weeks post baseline and 10% at 28 to 34 weeks gestation. CONCLUSIONS: A 3-day course of CVC appears to be well tolerated by the mother and statistically significantly more efficacious than placebo in the treatment of BV during the second trimester of pregnancy.

Administration, Intravaginal↗
PubMed2003

The role of infection in preterm labour and birth.

Preterm birth is the major cause of neonatal mortality and morbidity. Infection is a major cause of preterm labour. Abnormal genital tract flora in early pregnancy is predictive of preterm labour. Antibiotics may be of help in preventing preterm birth.

Anti-Bacterial Agents↗
PubMed2003

The development and introduction of anti-oxytocic tocolytics.

The perfect tocolytic agent, which is completely safe for both the mother and fetus and, which will inhibit uterine contractions and stop preterm labour in every case does not exist and the search continues. Recently, research into a new group of tocolytic agents (the oxytocic antagonists) has led to the introduction of a new licensed drug, atosiban. Since the early 1950s, modifications of the oxytocin molecule have resulted in many analogues and antagonists, though initially none emerged as potentially useful drugs. Further modifications resulted in full uterotonic antagonism in animal models before an analogue was found that inhibited vasopressin-stimulated uterine contractions in non-pregnant healthy women. In vitro and animal models suggested the molecule was fully antagonistic, although it was found to be only partially agonistic in women. Further developments led to two modified oxytocin molecules with higher receptor affinity for human myometrium, both of which lacked agonism in humans. The analogue, atosiban, was found to be more potent and so was chosen for clinical evaluation in dysmenorrhoea and preterm labour. The first clinical reports were open label, observational pilot studies. Randomised, double-blind, phase II placebo-controlled studies followed showing that atosiban was significantly more effective than placebo with very few side effects. Dose-response studies and phase III studies in which study or placebo groups could use alternative tocolytic agents also suggested that atosiban was an effective tocolytic agent with very few adverse events. The recent worldwide comparative study of atosiban versus different beta-agonists represents the largest and most strictly controlled study of tocolytics ever published. Atosiban was found to be at least as effective as the beta-agonists as a tocolytic agent, but significantly less likely to result in maternal cardiovascular side effects or the need to discontinue therapy as a result of unacceptable side effects.

Clinical Trials, Phase II as Topic↗
PubMed2003

Looking to the future.

Since the 7th and 13th Study Groups of the Royal College of Obstetricians and Gynaecologists met in 1977 and 1985, respectively, no meeting of this magnitude has convened to discuss the problems of spontaneous preterm labour and delivery and the associated fetomaternal mortality and morbidity. In the 17 years or so since that time, advances have been made in our understanding of the mechanisms of labour, the role of infection, the benefit of antepartum corticosteroids and the development of safer more specific tocolytics. In the future, an understanding of the genetic risk of spontaneous preterm labour and preterm birth is essential, particularly with respect to the predisposition to produce potentially damaging pro-inflammatory cytokines. The examination of the tissue damage will require pathologists specifically trained in perinatal pathology if the aetiology is to be ascertained and future management tailored to the risks. A greater understanding of fetomaternal immunology and response to antigen exposure in pregnancy may help us to understand which fetomaternal pairs are at greatest risk of responding by delivering preterm, with greater or lesser tissue damage than others with similar risk. Specifically, the relation between spontaneous preterm labour and proteinuric pre-eclampsia with their common immunology, inflammatory response and tissue damage leading to either spontaneous preterm labour or iatrogenic preterm birth will need to be addressed. This meeting has been very clinically and obstetrically orientated, in future we will need to involve epidemiologists, neonatologists, microbiologists, genito-urinary medicine physicians, immunologists, geneticists, biochemists, physiologists and endocrinologists. Although spontaneous preterm labour and preterm birth are the major causes of perinatal mortality and morbidity in the developed world, the definition and management protocols for spontaneous preterm labour varies from unit to unit and country to country. A process has already begun, hopefully fuelled by this meeting and those attending, to develop an international consensus on definitions and evidence-based practical guidelines on the management of spontaneous preterm labour. Perhaps in the longer term it may be possible to influence standards of care, outcome measures and training across international boundaries.

Adrenal Cortex Hormones↗