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Biomedical subjects

J T Queenan

Publications and source records attributed to J T Queenan.

At least 19 recordsLinked to original sources
PubMed1992

Clinical study of the lactational amenorrhoea method for family planning.

The effect of breastfeeding on fertility is well known; however, its use as a method of family planning was, until recently, untested. In 1988, the Bellagio Consensus Conference proposed guidelines that became the basis for a method of family planning called the lactational amenorrhoea method (LAM). The principle of LAM is that a woman who continues to fully or nearly fully breastfeed her infant and who remains amenorrhoeic during the first 6 months postpartum is protected from pregnancy during that time. We have assessed this method in the context of a breastfeeding support intervention study of 422 middle-class women in urban Santiago, Chile. The cumulative 6-month life-table pregnancy rate was 0.45% among women who relied on LAM as their only family planning method (1 woman pregnant in month 6). The findings indicate that LAM, with its high acceptance and efficacy, is a viable method of family planning and can safely serve as an introductory method for breastfeeding women.

Adolescent↗
PubMed1992

Acute prolactin and oxytocin responses and milk yield to infant suckling and artificial methods of expression in lactating women.

Breast-feeding is today the major form of infant nutrition in the immediate postpartum period. Despite this, recent trends in modern life-styles have raised obstacles to successful lactation. These include infant illness and maternal responsibilities outside the home, both requiring separation from the mother. While the hormonal dynamics of infant suckling are understood, little is known about the effects of artificial methods of milk expression. A variety of breast pumps exist in the current US market which vary considerably in price and effectiveness. To understand better the ability of these pumps to assist women in the maintenance of lactation, the current study was undertaken to evaluate their effects on milk yield and prolactin and oxytocin release when compared to natural infant suckling. Twenty-three women who were exclusively breast-feeding their infants were randomly assigned to serially use several pumping methods, as well as infant suckling, with blood being taken at 10-minute intervals to determine the hormonal responses. The results reveal variability in the prolactin responses to the artificial pumping methods, with the greatest responses found with an electric pulsatile pump; these responses compare favorably with those of natural infant suckling. Other methods were less successful in causing prolactin elevations. No differences were seen among the methods in the oxytocin response. The results of this study demonstrate striking differences in the ability of breast-pumping methods to produce an acute and sustained prolactin rise in breast-feeding mothers. The large discrepancies found suggest the need for further studies in to enable women and health care providers to choose the most appropriate method for milk expression.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Stillbirth rate and associated risk factors among 869 750 Latin American hospital births 1982-1986.

Fetal death is essential to evaluate perinatal outcome. Accurate stillbirth rate however is difficult to obtain; this is especially so in developing countries. Current information was obtained through a clinical-epidemiological study, ECLAMC, during the 1982-1986 period for a total sample of 869 750 births in 102 hospitals belonging to 11 Latin American countries. The overall stillbirth rate was 2.0%, the highest being in Bolivian (4.4%) and the lowest in Chilean hospitals (0.9%). In all countries there was a high mortality rate among male fetuses. The incidence of stillbirth in multiple pregnancies almost doubled that for singletons. A steady increase with increasing maternal age was observed. The proportion of all births in mothers 35 years of age or older was 10.1%, while the stillbirth proportion among all stillbirths in the same maternal age group was 18.8%. As expected, a higher fetal mortality rate (10.7%) was found in the low birthweight group (less than or equal to 2500 g) than in the group with birthweight greater than 2500 g (0.6%). One out of ten births occurred in the former group. A striking difference was observed in the stillbirth rate between hospitals with free obstetrical care (2.5%) and those in which any type of payment was required (1.4%). Although socioeconomical factors are probably the main factors responsible for fetal death, increased maternal age and a high incidence of low birthweight also contributed greatly to fetal mortality. These risk factors for fetal mortality should be the target of public health actions in these countries.

Adolescent↗
PubMed1991

Natural family planning: looking ahead.

Natural family planning is used by a relatively small number of people worldwide. The Institute's goal is to increase the knowledge, availability, effectiveness, and acceptability of natural family planning. To do so, the Institute is conducting biomedical research in several areas including: (1) the development of a home test kit for ovulation prediction, (2) sperm-mucus interaction, (3) the mechanisms and fertility impact of lactational amenorrhea, and (4) outcome of pregnancies in natural family planning users.

Amenorrhea↗
PubMed1991

Fetal outcome among pregnancies in natural family planning acceptors: an international cohort study.

This international, multicenter, prospective cohort study examines the outcome of pregnancies associated with aging gametes. Comparing pregnancies conceived at or near the peak mucus phase with those occurring before or after the peak provides a means of evaluating the effect of aging gametes. The outcome criteria are (1) rates of spontaneous abortion, (2) low birth weight, and (3) congenital malformations. Preliminary analysis shows a trend toward increased spontaneous abortion with aging gametes in certain subsets (women with prior pregnancy losses) but no effect on birth weight. Too few method failures have yet been studied to make a definitive statement on congenital malformations.

Family Planning Services↗
PubMed1989

Does midtrimester delta OD450 of amniotic fluid reflect severity of Rh disease?

Thirty-two patients with Rh-immunized pregnancies had amniocenteses between 16 and 20 weeks' gestation. Serial amniotic fluid values of delta optical density at 450 nm were studied to predict the severity of Rh disease. A value greater than 0.15 indicated severe Rh immunization. Values less than 0.09 indicated mild or no Rh disease; delta optical density at 450 nm between 0.09 and 0.15 require further evaluation to determine the trend. Midtrimester amniocentesis is a simple technique that helps to determine which patients may or may not require fetal blood sampling.

Amniotic Fluid↗
PubMed1989

The inhibition of human adrenal steroidogenic enzyme activities by suramin.

Suramin has recently been used to treat patients with acquired immune deficiency syndrome because of the action of this drug on reverse transcriptase. Patients so treated developed the symptoms and hormonal profiles of adrenal insufficiency. To evaluate the mechanism of action of suramin on adrenalcortical function, adrenal mitochondrial and microsomal preparations from five subjects were assayed for steroidogenic enzyme activity in the presence and absence of suramin. Specifically, 3 beta-hydroxysteroid dehydrogenase/isomerase, 17 alpha-hydroxylase, 21-hydroxylase, 11 beta-hydroxylase, and 17,20-desmolase activities were measured in the presence of 0-5000 mumol/L suramin concentrations. In all assays, enzyme activities decreased in a dose-dependent fashion as suramin concentrations increased. The drug doses (calculated) that caused 50% inhibition of enzyme activity were: 21-hydroxylase activity, 50 mumol/L; 17 alpha-hydroxylase activity, 25 mumol/L; 17,20-desmolase activity, 50 mumol/L; 11 beta-hydroxylase, 2 mumol/L, and 3 beta-hydroxysteroid dehydrogenase/isomerase, 1200 mumol/L. These results suggest that suramin has a concentration-dependent inhibitory effect on the key P-450-regulated enzymatic steps in adrenal glucocorticoid steroidogenesis, which may explain the development of adrenal insufficiency in acquired immune deficiency syndrome patients treated with suramin.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Plasminogen activator inhibitor types 1 and 2 in human trophoblasts. PAI-1 is an immunocytochemical marker of invading trophoblasts.

Trophoblast implantation, vascular remodeling, and maintenance of intervillous blood flow may depend on the regulated production of proteolytic enzymes such as plasminogen activator (PA). Since the functional activity of plasminogen activators is determined not only by the quantity of protease but also by levels of specific plasminogen activator inhibitors (PAI), we examined trophoblasts both in vitro and in vivo for the presence of two PAIs, PAI-1 and PAI-2. Cytotrophoblasts were isolated from first trimester or term placentae, cultured, and immunocytochemically stained using specific anti-PAI antibodies. The antiserum against PAI-1 demonstrated prominent cell-surface staining and some cytoplasmic staining. The antiserum generated against PAI-2 revealed a cytoplasmic localization, with some trophoblasts staining intensely, whereas others had no apparent reactivity. We also found that cultured cytotrophoblasts contain the mRNAs for PAI-1 and PAI-2. Immunohistochemical analysis of tissue sections from 8-, 16-, and 40-week implantation sites using antisera against PAI-1 demonstrated weak staining of villous syncytiotrophoblasts but prominent cytoplasmic staining of trophoblasts invading the decidua and myometrium. Antisera against PAI-2 stained the cytoplasm of villous syncytiotrophoblasts, but no staining was evident in villous cytotrophoblasts or in invading trophoblasts. We conclude that 1) human trophoblasts can express both PAI-1 and PAI-2 in vitro and in vivo and 2) prominent PAI-1 immunostaining defines invading trophoblasts, whereas PAI-2 is the predominant PAI accumulated in villous syncytiotrophoblasts. Thus, the various trophoblast forms have distinctive patterns of PAI expression.

Cells, Cultured↗
PubMed1988

Pregnancy outcome associated with natural family planning (NFP): scientific basis and experimental design for an international cohort study.

Although natural family planning (NFP) is a form of contraception without ostensible maternal risks (other than pregnancy), potential fetal risks could exist if aging gametes are involved in inadvertent fertilization. In the following report, we first review animal studies firmly establishing that aging sperm and aging oocytes (delayed fertilization) cause chromosomal abnormalities in mammals and other species. We next review human studies associating decreased coital frequency with trisomy and studies of NFP populations that generally show no increased frequency of anomalous offspring or spontaneous abortions. Our rationale for initiating an international cohort study is presented, along with the experimental design selected. Preliminary findings indicate that the experimental design chosen will indeed provide information allowing NFP safety to be assessed definitively.

Aging↗
PubMed1987

Regulation of urokinase-type plasminogen activator production by cultured human cytotrophoblasts.

Cultured human cytotrophoblasts synthesize and secrete urokinase-type plasminogen activator (uPA) during the first 24 h of culture, but secretion declines during the subsequent day. In contrast, synthesis and secretion of fibronectin increases during the 2 days of culture. The levels of uPA mRNA parallel the changes in synthesis and secretion of uPA. Treatment of cytotrophoblasts with 8-bromo-cAMP (1.5 mM) transiently raises uPA mRNA levels and uPA secretion. This treatment reduces fibronectin mRNA levels and causes a sustained increase in beta chorionic gonadotropin mRNA content and chorionic gonadotropin secretion. We conclude that a cAMP-mediated process up-regulates uPA expression in cytotrophoblasts. However, the stimulatory effect of the cyclic nucleotide analog on uPA is transient.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1986

Midtrimester amniotic fluid delta optical density at 450 nm in normal pregnancies.

Spectrophotometric analysis of amniotic fluid has become the standard for assessing the fetal condition in Rh-immunized pregnancies. Serial amniocentesis is usually started at 28 to 29 weeks of gestation unless the antibody titer or history indicates it should be done earlier. This study presents the values from 14 to 20 weeks in normal pregnancies, which will also assist in evaluating pathologically elevated values.

Adult↗
PubMed1986

Effect of induced oligohydramnios on fetal lung development.

To investigate the impact of oligohydramnios on fetal growth, development, and lung function, amniotic fluid was shunted from alternate gestational sacs into the maternal peritoneal cavity at 23 days' gestation in the fetal rabbit. Uninstrumented fetuses served as controls. Oligohydramnios was confirmed at the time of planned cesarean delivery on either day 26 or 28. Fetuses subjected to prolonged oligohydramnios had significantly decreased body weight at 26 (p = 0.002) and 28 days (p = 0.007). Similarly, lung weight was decreased at 26 (p = 0.02) and 28 days (p = 0.005). There was a trend toward decreased maximum lung volume for instrumented fetuses at 28 days (p = 0.07). Deflation limbs of the pressure-volume curves revealed significantly increased air trapping for instrumented fetuses at 28 days. These studies suggest not only a detrimental effect of oligohydramnios on fetal body and lung weight but also a beneficial effect of premature rupture of membranes on fetal lung function. Analysis of phospholipid and histologic changes is currently under way.

Amniotic Fluid↗
PubMed1986

Present status of intrauterine treatment of hydrocephalus and its future.

At a time when the intrauterine diagnosis of hydrocephalus is common and pioneering efforts of antenatal therapy are evolving, an assessment of intrauterine treatment of this disorder becomes pertinent. Consequently, the current status of the intrauterine treatment of fetal hydrocephalus is presented. The new data from the International Fetal Surgery Registry at the University of Manitoba in Winnipeg are discussed. The technical problems of antenatal shunting, the clinical trials, and experimental treatment are assessed. The prognostication and possible new approaches in intrauterine treatment of hydrocephalus are presented as well as the new diagnostic and surgical techniques. The outcome of the antenatal diagnosis and treatment of fetal hydrocephalus is evaluated.

Animals↗