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Biomedical subjects

C M Cook

Publications and source records attributed to C M Cook.

At least 37 records · Page 2Linked to original sources
PubMed1997

Hypertension in pregnancy: a study of the Asia-Oceania region.

A review of the management practices and problems surrounding hypertension in pregnancy in the Asia-Oceania region was made. This review was achieved by surveying institutions in the region. Sixteen countries responded to this survey and the results were analysed. Both rural and city hospitals were involved in the survey. The centres were selected by members of the Maternal Perinatal Committee of the Asia-Oceania Federation of Obstetrics and Gynaecology (AOFOG) under whose patronage the survey was performed. Analysis of the survey revealed a number of problems which could be addressed by appropriate educational interventions, these included drug therapies and protocols, deficiencies in governmental support especially in transport and centralised intensive care facilities. Public awareness was also a priority to be addressed. The role of the traditional birth attendant has been increasingly recognised as a resource which could be utilised. This is highlighted in this survey where there are countries who will be dependent on these carers for the next 10 years at least. Their place in the management of hypertension is discussed.

Asia↗
PubMed1997

Why we choose caesarean section: a prospective study.

We wished to inquire into the reasons why obstetricians choose Caesarean section as the preferred delivery mode and how they make that decision in individual settings. We therefore surveyed obstetricians to ascertain the obstetrical events at the time of decision and the reasons for the decision. Two hospitals with the same consultant medical staff were chosen for the study, The Jamison Private Hospital and the Nepean Hospital. The study group was analyzed using hospital, classification, parity, whether the procedure was elective or in labour, the stage of labour at which the Caesarean section was performed, and the primary and secondary reasons for the decision. Six hundred and twenty-four women were studied. When comparing the 2 institutions, there were 2 statistically significant findings. Firstly, the women at The Nepean Hospital were younger (27.9 +/- 5.6) than at Jamison Private Hospital (30.5 +/- 4.4; p < 0.001). Secondly, in the numbers of women undergoing Caesarean section in the 'failure to progress' category, there was a higher incidence (p < 0.001) at the private hospital. Apart from these differences, the 2 groups were remarkably similar.

Adult↗
PubMed1997

Experimental induction of the "sensed presence" in normal subjects and an exceptional subject.

9 of the 15 volunteers who were exposed to successive 3-min. durations of bursts of different types of weak (1 microT) complex magnetic fields or sham-fields reported the sense of a presence as indicated by a button press at the time of the experience. Reports of subjective experiences indicated that attempts to "focus" cognitively upon the location of the presence altered its location or induced its "movement." An exceptional subject who had a history of experiencing within his upper left peripheral visual field "flashing images" concerning the health and history of people [when handling their photographs] was also exposed to the burst sequences. Numbers of button presses associated with the experiences of a mystical presence, to whom the subject attributed his capacity, increased when the complex magnetic fields were applied without the subject's knowledge. The results support the hypothesis that the sense of a presence, which may be the common phenomenological base from which experiences of gods, spirits, angels, and other entities are derived, is a right hemispheric homologue of the left hemispheric sense of self.

Adult↗
PubMed1997

[3H]RY 80: A high-affinity, selective ligand for gamma-aminobutyric acidA receptors containing alpha-5 subunits.

The radiochemical synthesis and pharmacological properties are described of [3H]RY 80 (ethyl-8-acetylene-5, 6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5a][1, 4]benzodiazepine-3-carboxylate, [ethyl-3H]). This compound is one of a series of 8-substituted imidazobenzodiazepines that exhibits both high affinity and selectivity for gamma-aminobutyric acid (GABA)A receptors containing alpha-5 subunits. Saturable, high-affinity (Kd approximately 0.7 nM) binding of [3H]RY 80 was observed in hippocampal membranes. The maximum number (Bmax) of [3H]RY 80 binding sites was approximately 18% of that obtained with [3H]flunitrazepam, a radioligand that labels all "diazepam-sensitive" GABAA receptors. This value is consistent with previous estimates (10-20%) of the proportion of rat hippocampal GABAA receptors containing alpha-5 subunits determined by immunoprecipitation with selective antibodies and competition experiments using an alpha-5-selective ligand. In recombinant GABAA receptors composed of alpha-5 beta-3 gamma-2 subunits, the Kd of [3H]RY 80 (approximately 0.5 nM) was consistent with the value obtained in hippocampus, whereas the Bmax value was not significantly different from that obtained with [3H]flunitrazepam. The potencies of several benzodiazepine site ligands to inhibit [3H]RY 80 binding to hippocampal membranes were in agreement with the values obtained in recombinant (alpha-5 beta-3 gamma-2) GABAA receptors. [3H]RY 80 was used both in a "GABA shift" assay to correctly predict the in vivo actions of a novel, alpha-5-selective ligand and to characterize a population of GABAA receptors containing alpha-5 subunits in neonatal rat cortex. These findings demonstrate that [3H]RY 80 can be used as a radioligand to examine the properties of GABAA receptors containing alpha-5 subunits.

Alkynes↗
PubMed1996

A randomized controlled trial of aspirin in patients with abnormal uterine artery blood flow.

OBJECTIVE: To evaluate color Doppler imaging of the uterine arteries as a screening test in nulliparous women, and to examine the role of low-dose aspirin therapy in pregnancies with abnormal uteroplacental resistance. METHODS: At the routine 18-week fetal morphology ultrasound scan, 955 nulliparous women underwent color Doppler imaging of the uterine arteries. Abnormal uteroplacental vascular resistance was defined with respect to both the systolic-diastolic ratio of the flow velocity waveform and the presence of an ipsilateral early diastolic notch. Those with abnormal uterine artery waveforms were asked to participate in a randomized controlled trial of aspirin therapy. Pregnancy outcomes were compared in women with normal or abnormal flow velocity waveforms, as well as in the two arms of the intervention study. RESULTS: Of 186 women with abnormal uteroplacental resistance according to criteria defined previously, 102 agreed to randomization to either low-dose aspirin (100 mg/day) or placebo for the remainder of the pregnancy. Abnormal uterine artery flow velocity waveforms were associated with statistically significant increases in preeclampsia (11 versus 4%), birth weight below the tenth percentile (28 versus 11%), and adverse pregnancy outcome (45 versus 28%). Prophylactic aspirin therapy did not result in a significant reduction in pregnancy complications. CONCLUSION: Abnormal uteroplacental resistance at 18 weeks' gestation was associated with a significant increase in adverse pregnancy outcome. Low-dose aspirin did not reduce pregnancy complications in women with uteroplacental insufficiency.

Adult↗
PubMed1996

A longitudinal study of the cervix in pregnancy using transvaginal ultrasound.

OBJECTIVE: To study longitudinal changes in the cervix during pregnancy using transvaginal ultrasound and secondly, to determine whether the measures used change with gestational age, and whether there are differences between nulliparous and primiparous women. DESIGN: A longitudinal study involving five transvaginal ultrasound examinations of each woman at specified gestational ages from 18 to 30 weeks. PARTICIPANTS: Twenty-one nulliparous and 20 primiparous women completed the study and were delivered at term. Cervical length, diameter and dilation were assessed at each examination. RESULTS: In both nulliparous and primiparous women there is no significant change in either cervical length or diameter over the time period studied. In primiparous women the cervix is significantly longer than in nulliparous women (44.4 (5.1) mm versus 40.6 (4.7) mm [mean (SD)]; P< 0.001). The cervical diameter in primiparous women is also significantly greater (31.8 (4.0) mm versus 29.0 (3.7) mm; P<0.001). CONCLUSIONS: Cervical length and diameter are constant in both nulliparous and primiparous women throughout this gestational period. The cervix in primiparous women is both longer and thicker than in nulliparous women.

Adolescent↗
PubMed1994

Toxin extraction from an Anabaenopsis milleri--dominated bloom.

This paper reports the presence of microcystin type toxins in extracts of a natural bloom of cyanobacteria composed predominantly of Anabaenopsis milleri Woronichin. The toxins have been extracted, purified and compared to microcystin-LR. The LD50 of A. milleri bloom material was 600-1500 mg lyophilized cells/kg body weight. Symptoms and pathological signs of poisoning in mice were characteristic of cyanobacterial hepatotoxins, with enlarged darkened livers with weights of 8-10% of the total body weight. Thin-layer chromatography of the extract resulted in one toxic band, which was separated from pigments and 280-nm absorbing compounds. The toxic fraction was further separated using reversed phase high performance liquid chromatography and one toxic band was recovered. This fraction yielded a single, toxic peak with a retention time of 11.3 min after high performance liquid chromatography. The absorption spectrum of the purified toxin had a maximum at 238-240 nm and was characteristic of cyanobacterial hepatotoxic peptides. Comparison of the chromatographic behaviour of the purified toxin with microcystin-LR on reversed phase and on internal surface reversed phase, high performance liquid chromatography indicated that an A. milleri bloom material toxin was a microcystin type toxin and it is highly likely that the purified toxin is microcystin-LR.

Animals↗
PubMed1993

Angiotensin sensitivity predicts aspirin benefit in placental insufficiency.

OBJECTIVE: To determine whether the beneficial effects of aspirin in the treatment of Doppler umbilical placental insufficiency correlate with the maternal pressor response to angiotensin infusion. DESIGN: An open trial. SETTING: A tertiary referral obstetric service. PATIENTS: Women identified at between 25 and 36 weeks of pregnancy with an elevated umbilical artery Doppler systolic/diastolic (S/D) ratio and a positive pressor response to angiotensin infusion. INTERVENTION: Low dose aspirin (100mg/day) treatment of mothers. MAIN OUTCOME MEASURE: Fetal and placental size at delivery in relation to subsequent maternal angiotensin responsiveness. RESULTS: Women who converted from a positive angiotensin pressor response to angiotensin refractoriness after aspirin administration had larger infants and placentas compared with those whose response remained positive. CONCLUSION: Angiotensin sensitivity predicts women with umbilical Doppler detected placental insufficiency responding to aspirin therapy. Loss of the normal refractory response in pregnancy may be a consequence of vascular pathology in the placenta.

Angiotensins↗
PubMed1991

Computer modelling of the 3-dimensional structures of the cyanobacterial hepatotoxins microcystin-LR and nodularin.

The 3-dimensional structures of two cyanobacterial hepatotoxins microcystin-LR, a cyclic heptapeptide and nodularin, a cyclic pentapeptide, and the novel amino acid ADDA (3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl-4,6-decadienoic acid) were constructed, and optimized using the CHEM-X molecular mechanics program. The peptide rings were planar and of rectangular shape. Optimized ADDA formed a U-shape and a difference in the orientation of ADDA with respect to the peptide ring of the two hepatotoxins was observed.

Computer Simulation↗
PubMed1991

Fetal umbilical artery velocity waveforms and subsequent neonatal outcome.

Flow velocity waveforms (FVWs) from the fetal umbilical artery were recorded from 2178 pregnant women over a 6-year period. All of them had an obstetric factor indicating increased risk of fetal compromise. A total of 6749 studies was recorded. The systolic diastolic (AB) ratio was measured and classified as normal (less than 95th centile), elevated (95-99th centile), high (greater than 99th centile) or extreme (absent diastolic flow). The results of these studies have been related to subsequent fetal and neonatal outcome. An abnormal umbilical artery FVW was associated with shorter gestation and infants with lower birthweight, shorter length and lower ponderal index. There was a highly significant association between an abnormal FVW and the birth of an infant small for gestational age. The significance of the association increased with the increased abnormality of the umbilical artery FVW and this was independent of gestational age. Preterm infants associated with high or extreme AB ratios spent twice as long in the neonatal nursery than those with normal AB ratios. Analysis of 794 pregnancies studies serially indicated that an abnormal FVW in which the AB ratio was increasing, in contrast to a decreasing AB ratio, predicted a poor outcome for both size at birth and duration of neonatal intensive care. We conclude that in high risk pregnancy Doppler umbilical artery FVW studies predict the most compromised fetuses in terms of growth retardation and requirements for neonatal intensive care.

Adult↗
PubMed1991

Maternal angiotensin sensitivity and fetal Doppler umbilical artery flow waveforms.

The angiotensin pressor response was investigated in normotensive pregnancies which had umbilical Doppler flow velocity waveforms suggestive of placental vascular disease. Of the 36 pregnancies studied at between 24 and 38 weeks gestation, 18 had a positive response to the angiotensin pressor test, these women were delivered earlier (35.3 vs 38.5 weeks, P = 0.015), had a lower mean birthweight centile (14 vs 36, P less than 0.001) and higher frequency of fetal distress in labour (40% vs 7%, P = 0.06) when compared with the 18 women who had a negative response. The Doppler umbilical systolic-diastolic (S-D) ratio decreased with gestation in the negative group, suggesting continuing placental growth and vascular expansion, whereas the S-D ratio increased in the positive group (P less than 0.001), indicative of vascular obliteration. We suggest that the positive angiotensin pressor response is primarily associated with the placental vascular pathology. Angiotensin infusion had no acute effect on maternal uteroplacental or fetal umbilical artery flow velocity waveforms.

Angiotensin II↗
PubMed1990

The fetal breath cycle.

Fetal breathing movements may be timed precisely from the umbilical vein flow velocity profile recorded using Doppler ultrasound. Serial studies were performed on eight normal fetuses from 28 weeks pregnancy until delivery. Measurements were made of the inspiratory time, total breath time and breath amplitude. There was a clear change in the pattern of fetal breathing with advancing gestation. The inspiratory time lengthened and the amplitude of each breath increased. The variability of these measures decreased. The timing equation ti/ttotal lengthened. The area of change in the umbilical vein sonogram was calculated as a measure of respiratory work and this increased with gestation. It is suggested that the changing pattern of fetal breathing movements reflects changes in central control of breathing in the fetus and parallels observations in the newborn.

Embryonic and Fetal Development↗
PubMed1990

Doppler umbilical and uterine flow waveforms in severe pregnancy hypertension.

Doppler studies of the umbilical and uteroplacental bed arterial flow velocity waveforms were performed in a series of women suffering from severe proteinuric pregnancy hypertension. Ninety-five women were studied and the mean interval between the last study and delivery was 1.4 days. An abnormally elevated umbilical artery systolic:diastolic (AB) ratio was present in 61 (64%) of the women. All 10 perinatal deaths were associated with pregnancies with an abnormal umbilical artery AB ratio. An elevated umbilical artery AB ratio was significantly associated with small-for-gestation and neonatal morbidity. Infants associated with extremely high umbilical artery AB ratios (greater than or equal to 99th centile) spent twice as long in the neonatal nursery as those with a lower value. There was no relation between the duration of hypertension and the umbilical study result. The uteroplacental bed artery flow velocity waveform did not correlate with fetal or neonatal mortality or morbidity. Patients with abnormal uteroplacental AB ratios also had abnormal umbilical artery AB ratios. We conclude that an abnormal fetal umbilical artery Doppler flow velocity waveform correlates with adverse fetal outcome in severe proteinuric pregnancy hypertension and suggest that the associated placental lesion may precede the maternal hypertension.

Adolescent↗