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Biomedical subjects

P W Howie

Publications and source records attributed to P W Howie.

At least 19 recordsLinked to original sources
PubMed1995

Neonatal cerebral arterial flow velocity waveforms in term infants with and without metabolic acidosis at delivery.

To define the effects of acid base status at delivery on neonatal cerebral artery flow velocity waveform patterns obtained using Doppler ultrasound during the first week of life, a longitudinal comparative study of neonates born at term with and without evidence of metabolic acidosis in the umbilical artery was undertaken. Eighty-two appropriate for gestational age infants delivered after uncomplicated pregnancies with non-acidotic umbilical artery blood gases and in whom no neonatal complications were noted were studied to establish reference values of neonatal cerebral arterial vascular resistance index (RI) in normal term infants during the first week of life. A further 189 infants were grouped according to the presence and severity of metabolic acidosis at delivery, and also the presence of high risk features in the antenatal period. In the normal non-acidotic infants, over the first 24 h of life, there was a significant fall in the cerebral arterial resistance index (RI) in all the vessels examined, after which a steady state value was attained with no significant changes in vascular resistance index being noted during the remainder of the study period. The fall in RI between 12 and 24 h of age was consistent in all study groups. Infants with metabolic acidosis at delivery had blood flow patterns compatible with decreased resistance to flow in both anterior and middle cerebral arteries which persisted throughout the first week of life. This reduction in cerebral vascular resistance was most marked in those infants with severe metabolic acidosis. The majority of severely acidotic infants had a benign clinical outcome in the first week of life and all infants had normal cerebral ultrasound scans during the neonatal period. These findings suggest that metabolic acidosis at birth is associated with changes in neonatal cerebral arterial vascular resistance during the first week of life, and in the presence of benign clinical course the significance of this observation with regard to neurodevelopmental outcome requires evaluation.

Acidosis↗
PubMed1991

Screening for Down's syndrome based on individual risk.

OBJECTIVE: To evaluate the effectiveness of biochemical screening of individual pregnancies for Down's syndrome risk. DESIGN: Retrospective determination of risk. SETTING: Obstetric and cytogenetic services in Tayside, Scotland. SUBJECTS: 3436 pregnant women who had screening for neural tube defects in the second trimester during November 1988 to March 1990 and whose pregnancies were dated by ultrasonography. Three women with pregnancies associated with Down's syndrome reported later in 1990. MAIN OUTCOME MEASURES: Individual risk calculated from age at estimated date of delivery; chorionic gonadotrophin and alpha fetoprotein concentrations in serum samples obtained at precisely determined gestational ages in second trimester. Results of karyotype determination and outcome of pregnancy. RESULTS: During November 1988 to March 1990 karyotypes were determined for 5% of pregnancies for reasons of maternal age and genetic history and one of the eight affected fetuses was detected. Individual risk could not be calculated for 347 pregnancies, but screening on this basis would have detected five of the cases and required screening in 194 out of 3089 (6.3%) pregnancies; all three affected pregnancies reported later in 1990 would also have been detected, giving a success rate of 73% (95% confidence interval 39% to 94%). The age distribution of women according to individual risk suggests that women over 35 would be screened effectively. CONCLUSION: Screening based on individual risk would use resources more effectively than screening based on maternal age and genetic history without affecting detection rates in older women.

Adult↗
PubMed1991

Breastfeeding: a natural method for child spacing.

Lactational amenorrhea plays an important role in child spacing. Recent research has led to a consensus regarding the status of lactational amenorrhea as a method of family planning. This is currently referred to as the lactational amenorrhea method. Research priorities were to field test the lactational amenorrhea method and define the factors that influence lactational amenorrhea and the interface between the lactational amenorrhea method and other family planning methods.

Amenorrhea↗
PubMed1990

Prevalence of HIV antibody and pregnancy in Tayside, 1984-9: background to screening.

OBJECTIVE: To determine age specific prevalence of HIV antibody, incidence of pregnancy, and likelihood of detection and correct assignment to risk category by antenatal screening of women known to be positive for HIV antibody, from 1984 to 1989. DESIGN: Retrospective analysis of reproductive history and risk behaviour of women positive for HIV antibody and prediction of detection by screening on the basis of blood group samples, Guthrie tests, and rubella tests. SETTING: City of Dundee, where the prevalence of HIV is high, since the appearance of HIV in 1984, predominantly among heterosexual intravenous drug users. PATIENTS: All (61) women known to be positive for HIV antibody who had had clinically indicated tests, for whom case notes were available for 60. MAIN OUTCOME MEASURES: Risk assessment according to case notes and reported to the laboratory, incidence of infection, geographical location, age, date of positive test result, and reproductive history. RESULTS: With 61 infected women the overall minimum prevalence among women within the city of Dundee was 0.67/1000 and 2.9/1000 among women in their third decade. Of the 60 women whose reproductive history was available, 35 had 57 pregnancies, 36 of which occurred after seroconversion was known to have taken place, representing 8.7% of the total number of affected pregnancies reported for the United Kingdom. If antenatal screening for HIV had been performed between 1984 and 1989 it could not have detected positivity for HIV antibody in 25 (42%) women who had no pregnancies during this time. Among the remaining 35 women, screening samples taken for blood grouping could have identified a maximum of 34 (57%), samples taken to check rubella susceptibility a maximum of 22 (37%), and blood spots on Guthrie cards a maximum of 19 (32%). Retesting would have occurred in 14 women 33 times with samples taken for blood grouping, but three and four women would have been tested twice using samples taken for rubella testing and Guthrie cards respectively. Anonymous screening would have been unable to determine risk category as a history of intravenous drug use was known in 47 (79%) women before testing but this was increased by a further 5 (8%) who admitted to it after the test result was known. CONCLUSION: Interpreting the results of antenatal screening programmes will be complex and will underestimate overall prevalence of HIV antibody among women; this will be exaggerated by strategies based on anonymous testing with Guthrie cards or on samples taken for rubella testing, which do not include women who have had an earlier loss of pregnancy. Only open testing with consent will permit satisfactory attribution to

Acquired Immunodeficiency Syndrome↗
PubMed1990

Protective effect of breast feeding against infection.

OBJECTIVE: To assess the relations between breast feeding and infant illness in the first two years of life with particular reference to gastrointestinal disease. DESIGN: Prospective observational study of mothers and babies followed up for 24 months after birth. SETTING: Community setting in Dundee. PATIENTS: 750 pairs of mothers and infants, 76 of whom were excluded because the babies were preterm (less than 38 weeks), low birth weight (less than 2500 g), or treated in special care for more than 48 hours. Of the remaining cohort of 674, 618 were followed up for two years. INTERVENTIONS: Detailed observations of infant feeding and illness were made at two weeks, and one, two, three, four, five, six, nine, 12, 15, 18, 21, and 24 months by health visitors. MAIN OUTCOME MEASURE: The prevalence of gastrointestinal disease in infants during follow up. RESULTS: After confounding variables were corrected for babies who were breast fed for 13 weeks or more (227) had significantly less gastrointestinal illness than those who were bottle fed from birth (267) at ages 0-13 weeks (p less than 0.01; 95% confidence interval for reduction in incidence 6.6% to 16.8%), 14-26 weeks (p less than 0.01), 27-39 weeks (p less than 0.05), and 40-52 weeks (p less than 0.05). This reduction in illness was found whether or not supplements were introduced before 13 weeks, was maintained beyond the period of breast feeding itself, and was accompanied by a reduction in the rate of hospital admission. By contrast, babies who were breast fed for less than 13 weeks (180) had rates of gastrointestinal illness similar to those observed in bottle fed babies. Smaller reductions in the rates of respiratory illness were observed at ages 0-13 and 40-52 weeks (p less than 0.05) in babies who were breast fed for more than 13 weeks. There was no consistent protective effect of breast feeding against ear, eye, mouth, or skin infections, infantile colic, eczema, or nappy rash. CONCLUSION: Breast feeding during the first 13 weeks of life confers protection against gastrointestinal illness that persists beyond the period of breast feeding itself.

Bottle Feeding↗
PubMed1990

Return of ovarian function following spontaneous abortion.

Assays of first morning urine samples for oestrone-3-glucuronide, LH and pregnanediol-3-glucuronide, were used to study endocrine function and return to ovulation in 18 subjects following spontaneous miscarriage. On the basis of the endocrine data, ovulation occurred in all 18 women in the cycle prior to first menses at a mean of 29 days post-partum (range 13-103 days) with one subject conceiving in that cycle. Compared with the second cycle, the first cycle after spontaneous abortion had similar levels of follicular phase peak ovulatory oestrone excretion but lower levels during the late luteal phase (P less than 0.02), lower levels of peak LH (50.5 IU/g creatinine (C) cf. 68.8 IU/g C; P less than 0.04) and lower late secretory peak pregnanediol (4.6 mg/g C cf. 6.1 mg/g C; P less than 0.02). The mean luteal phase length of 12.9 days in the first cycle was shorter than the mean of 14.4 days in the second cycle (P less than 0.02). These data show that, although there is some disturbance of endocrine function in the first cycle after spontaneous abortion, the majority of women have a rapid return to ovulation, making the early use of contraception necessary for those wishing to avoid conception.

Abortion, Spontaneous↗
PubMed1989

Fetal growth achievement and neurodevelopmental disability.

To investigate the role played by chronic intrauterine insult in the genesis of neurodevelopmental disability (NDD), three analyses have been applied to a case-controlled study which compared a population of children with NDD with a control group of normally developed children. In the first analysis, average birthweight in children with NDD was 3138 g (SD 592) which was significantly less than in normally developed children, 3280 g (SD 491) (P less than 0.0005). After correction for confounding factors, birthweight-for-gestation (Z score) remained lower in children with NDD (-0.42) than normal children (-0.21) (P less than 0.0025). In the second analysis the fetal growth achievement of children, who had NDD after the prenatal complications, severe hypertension, unclassified antepartum haemorrhage and preterm uterine activity, was significantly less (Z score, -0.76) than children who were normally developed after the same maternal prenatal complications (Z score, -0.37) (P less than 0.03). In the third analysis, a risk analysis to assess the relative importance of fetal growth achievement and prenatal complications in the genesis of NDD suggested that the latter was the dominant factor. These data are consistent with the hypothesis that prenatal complications, severe enough to retard fetal growth, can compromise fetal brain development and make an important contribution to NDD.

Adult↗
PubMed1988

Occult biochemical pregnancy: fact or fiction?

Daily urine samples were obtained from 38 women of proven fertility, who were attempting to conceive, to assess the frequency of clinically unsuspected "biochemical pregnancies' on the basis of late luteal phase rises of hCG. In 25 clinically confirmed conception cycles, the earliest pregnancy-induced hCG rises from baseline occurred 8 days after the endocrinologically defined date of ovulation (mean 11.1 days, SD 1.3). Urine samples obtained throughout 50 non-conception ovulatory cycles provided no evidence of any 'biochemical pregnancies' on the basis of late luteal phase rises of hCG occurring 8 or more days after the endocrinologically defined date of ovulation. If, as in previous studies, the date of ovulation had been estimated on the basis of menstrual cycle length and only the relatively non-specific NIH antiserum had been used in RIAs, 7 of the 50 (14%) cycles would have been classified as resulting in biochemical pregnancies on the basis of hCG greater than 50 m-i.u./ml on one occasion or greater than 20 m-i.u./ml on two or more occasions after day 20 of the cycle. These levels of 'hCG' occurred at or soon after ovulation and could be explained by LH cross-reacting in the RIA. The rises of 'hCG' were not confirmed when the urine samples were retested with an antiserum (Wellcome 895) of very high specificity for hCG. These results raise the possibility that the frequency of clinically unsuspected 'biochemical pregnancy' may have been substantially overestimated.

Adult↗
PubMed1987

Reduction in postprandial energy expenditure during pregnancy.

Energy expenditure was measured during pregnancy in seven primigravid women at 12-15, 25-28, and 34-36 weeks and after the cessation of lactation. On each occasion the resting metabolic rate and the increase in metabolic rate after ingestion of a liquid test meal were measured by indirect calorimetry. In absolute terms the resting metabolic rate increased steadily during pregnancy but when expressed per unit of body weight no change was found. The energetic response to a mixed constituent meal was significantly reduced by 28% in the middle trimester of pregnancy. These findings suggest a possible maternal adaptation to increase energetic efficiency at a time when the energy demands of the fetus are high.

Adaptation, Physiological↗
PubMed1987

Prolactin response to low dose sulpiride.

1 Prolactin levels in response to sulpiride were studied in healthy volunteers. 2 Oral doses of 1 mg-50 mg sulpiride or placebo were given. 3 A 3 mg sulpiride dose produced similar levels to those achieved with both 10 mg and 50 mg. 4 Circadian effects were studied showing no significant differences in the prolactin response to sulpiride. 5 Acute or chronic responses showed an attenuation with chronic sulpiride treatment to 50% of the peak levels attained with acute treatment. 6 These results indicate that sulpiride retains its potent ability to produce prolactin release even at the low doses studied here.

Adolescent↗
PubMed1987

Induction of transient hyperprolactinaemia in neonatal rats by direct or maternal treatment with the dopamine receptor blocker, sulpiride.

Prolactin was measured in the plasma of neonatal rats after iv and ip injection of the dopamine receptor blocking drug sulpiride, and after its ip injection to neonatal rats' nursing mothers. The sulpiride dose PRL response relationship in 10-25 day old neonatal rats was similar to that found in lactating rats, with a threshold sensitivity around 29 nmol sulpiride/kg body weight and a maximal response at about 2.9 mumol/kg. Absolute levels of PRL in the neonate (both peak and increment-over-basal) were, however, 90% lower than in adults. Treatment of lactating mothers with a maximally stimulatory dose of sulpiride (2.9 mumol/kg) twice daily for 4 days resulted in small but highly significant increases in neonatal PRL on days 1 and 2 but complete loss of response by day 4. These data demonstrate that there is a close similarity between the responses of maternal and neonatal rats to sulpiride and that transfer of the drug to the neonate via milk can induce neonatal hyperprolactinaemia. The subsequent loss of the neonatal PRL response on chronic exposure to sulpiride may indicate a degree of disturbance of hypothalamic dopaminergic mechanisms. In the clinical situation this would suggest that doses of dopamine receptor-blocking drugs used to enhance maternal milk production should be carefully chosen.

Animals↗