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Biomedical subjects

P O'Leary

Publications and source records attributed to P O'Leary.

At least 19 recordsLinked to original sources
PubMed1998

Decreased epinephrine responses to hypoglycemia during sleep.

BACKGROUND: In patients with type I diabetes mellitus, hypoglycemia occurs commonly during sleep and is frequently asymptomatic. This raises the question of whether sleep is associated with reduced counterregulatory-hormone responses to hypoglycemia. METHODS: We studied the counterregulatory-hormone responses to insulin-induced hypoglycemia in eight adolescent patients with type I diabetes and six age-matched normal subjects when they were awake during the day, asleep at night, and awake at night. In each study, the plasma glucose concentration was stabilized for 60 minutes at approximately 100 mg per deciliter (5.6 mmol per liter) and then reduced to 50 mg per deciliter (2.8 mmol per liter) and maintained at that concentration for 40 minutes. Plasma free insulin, epinephrine, norepinephrine, cortisol, and growth hormone were measured frequently during each study. Sleep was monitored by polysomnography. RESULTS: The plasma glucose and free insulin concentrations were similar in both groups during all studies. During the studies when the subjects were asleep, no one was awakened during the hypoglycemic phase, but during the final 30 minutes of the studies when the subjects were awake both the patients with diabetes and the normal subjects had symptoms of hypoglycemia. In the patients with diabetes, plasma epinephrine responses to hypoglycemia were blunted when they were asleep (mean [+/-SE] peak plasma epinephrine concentration, 70+/-14 pg per milliliter [382+/-76 pmol per liter]; P=0.3 for the comparison with base line), as compared with when they were awake during the day or night (238+/-39 pg per milliliter [1299+/-213 pmol per liter] P=0.004 for the comparison with base line, and 296+/-60 pg per milliliter [1616+/-327 pmol per liter], P=0.004, respectively). The patients' plasma norepinephrine responses were also reduced during sleep, whereas their plasma cortisol concentrations did not increase and their plasma growth hormone concentrations increased slightly. The patterns of counterregulatory-hormone responses in the normal subjects were similar. CONCLUSIONS: Sleep impairs counterregulatory-hormone responses to hypoglycemia in patients with diabetes and normal subjects.

Adolescent↗
PubMed1998

Sleep, respiratory rate, and growth hormone in chronic neonatal lung disease.

This study assessed whether respiratory rates (RRs) correlate with urinary growth hormone (U-GH) excretion and sleep architecture in infants with chronic neonatal lung disease (CNLD) in early (1 month), middle (6 months), and late (10 months) infancy. Twenty-three preterm infants (CNLD=16, controls=7) were studied on 51 occasions. CNLD infants were stratified according to mean non-REM sleep respiratory rate (NREM RR) in early infancy into "High RR CNLD" infants (mean NREM RR >2 SD higher than controls) and "Normal RR CNLD" infants (mean NREM RR within 2 SD of controls' mean). "High RR CNLD" infants (RR >45) had a lower mean birthweight (P=0.015), current weight (P=0.042), current length (P=0.02), and growth velocity in early infancy (grams/week gained: P=0.042) than "Normal RR CNLD" and control infants. Mean (95% CI) U-GH excretion (ng U-GH/g urinary creatinine) was higher in "High RR CNLD" infants in air or their usual O2 (1,932 [459, 3,406]) than "Normal RR CNLD" (394 [147, 642]) and controls (320 [147, 492]) (P=0.024). With resolution of tachypnea by mid-infancy, hemoglobin oxygen saturation (SaO2) >93%, mean growth parameters and U-GH excretion for the "High RR CNLD" group were not significantly different from "Normal RR CNLD" and control groups. CNLD infants demonstrated increased sleep efficiency (P=0.016), whereas controls had similar sleep efficiency between early and middle infancy (P=0.452). Mean percent time in REM sleep (REM%) and slow wave sleep (SWS%) were not significantly different between early and middle infancy and did not vary in relation to respiratory rate. We conclude that tachypneic infants with CNLD have slower growth and elevated U-GH excretion in early infancy. With resolution of tachypnea, growth improved, U-GH excretion decreased, and sleep consolidation occurred. An elevated U-GH in tachypneic CNLD infants may reflect stress, compromised nutrition (GH resistance), or a feedback loop involving a direct effect of GH on lung growth and repair.

Bronchopulmonary Dysplasia↗
PubMed1998

What makes a coronary myocardial bridge symptomatic?

The clinical significance of coronary myocardial bridging has been debated and different interventional strategies proposed. We discuss the case of a patient who presented with the recent onset of symptoms of exertional chest pain, diaphoresis, and electrocardiographic signs of acute anterior myocardial wall ischemia. Cardiac catheterization demonstrated a segmental high-grade narrowing of the mid left anterior descending coronary artery during systole consistent with bridging. Intravenous fluid resuscitation and calcium channel blockade resulted in normalization of his electrocardiogram and complete resolution of his anginal symptoms and coronary angiographic systolic narrowing.

Administration, Oral↗
PubMed1997

Thyroid function in a population of children with attention deficit hyperactivity disorder.

OBJECTIVE: To determine the prevalence of thyroid hormone abnormalities and generalized resistance to thyroid hormone in a population of children with attention deficit hyperactivity disorder (ADHD) as compared to reference ranges determined from a control population and hence to determine if routine thyroid hormone screening in children with non-familial ADHD is indicated. METHOD: Children attending the State Child Development Centre in Perth, Western Australia with ADHD, as defined by the Diagnostic and Statistical Manual of Mental Disorders (fourth edition) provided the study population. The control population consisted of 353 normal children with a history of allergy in whom radioallergosorbent (RAST) testing was being performed. RESULTS: The prevalence of thyroid hormone abnormalities in the study population was 2.3% (95% CI 0.6%, 5.7%). There were no cases of generalized resistance to thyroid hormone. The prevalence of thyroid hormone abnormalities in the general population of children and adolescents has been reported to vary between 1 and 3.7%. CONCLUSION: Routine thyroid hormone screening is not indicated in children with non-familial ADHD.

Adolescent↗
PubMed1996

The impact of antenatal screening for Down syndrome in Western Australia: 1980-1994.

Since the early 1970s, women in Western Australia have been screened for fetal Down syndrome risk on the basis of maternal age. Women 35 years of age or more at delivery, were offered fetal karyotyping with genetic diagnostic testing via amniocentesis or chorionic villus sampling. An increase in the prevalence of Down syndrome of 3.9% per year (95% confidence interval: 1.8-6.0%) was observed between 1980 and 1994, almost all of which was accounted for by increased maternal age. In 1991, a maternal serum screening (MSS) programme for Down syndrome was first implemented in Western Australia and has since evolved in 6 separate laboratories providing Down risk assessment in 1994. The gradual introduction of MSS programmes had little discernible impact until 1994, when 38% of Down syndrome fetuses were ascertained as a result of increased-risk MSS tests and the birth prevalence of Down syndrome decreased significantly. In this report, we review antenatal screening programmes and their impact on the birth prevalence of Down syndrome in Western Australia.

Adult↗
PubMed1996

Serum progesterone and human chorionic gonadotrophin measurements in the evaluation of ectopic pregnancy.

We evaluated the clinical usefulness of measuring the serum concentrations of human chorionic gonadotrophin (HCG) and progesterone to distinguish between early viable and nonviable pregnancies. We investigated 110 women with clinical symptoms of abnormal pregnancy. A single HCG measurement did not clearly distinguish between ectopic and failing intrauterine pregnancies; an HCG value below 3,000 IU/L, together with a serum progesterone below 40 nmol/L, predicted abnormal pregnancy outcome in 97% of women (positive predictive value: 91%; negative predictive value: 95%). Serum HCG value above 3,000 IU/L or progesterones above 40 nmol/L, discriminated between an ongoing pregnancy and an abnormal pregnancy in 87% women (positive predictive value: 95%; negative predictive value: 91%) and provided reassurance of an ongoing pregnancy. Our results suggest that a combination of serum progesterone and HCG measurements provide clinically useful biochemical information which enhances the prediction of pregnancy outcome.

Chorionic Gonadotropin↗
PubMed1994

Optical triple sensor for measuring pH, oxygen and carbon dioxide.

A triple sensor unit consisting of opto-chemical sensors for measurement of pH, oxygen and carbon dioxide in bioreactors is presented. The pH and the CO2 sensor are based on the color change of a pH-sensitive dye immobilized on a polymeric support. The resulting changes in absorption are monitored through optical fibers. The oxygen sensor is based on the quenching of the fluorescence of a metal-organic dye. All three sensors are fully LED compatible. The sensitive membranes consist of plastic films and can be stored and replaced conveniently. The sensors are sterilizable with hydrogen peroxide and ethanol. In addition, the pH sensor is steam sterilizable. Accuracy, resolution and reproducibility fulfill the requirements for use in biotechnological applications. Calibration procedures for each sensor are presented. The working principle and the performance of all three sensors are described, with particular emphasis given to their application in bioreactors.

Carbon Dioxide↗
PubMed1994

Ambulatory paediatric surgery. The development of a day-care surgical centre.

Ambulatory surgery has become an important component in the provision of surgical care. In 1987 a day-case surgical unit was established at Red Cross War Memorial Children's Hospital, Cape Town. Experience over a 6-year period (1987-1992) is reviewed in relation to the nature and total number of surgical procedures, pre-operative preparation, daily utilisation of the facility, postoperative care and complications. During this period 16,538 patients (mean age 3 years) were operated on in the unit. Nine surgical disciplines participated. Pre-operative assessment and preparation reduced the rate of cancellations on the day of surgery to less than 6%, with a 90% effective use of schedules operating time. Scarce nursing resources were also maximally utilised. Most procedures took less than 30 minutes and only 0.8% exceeded 1 hour. The average ward stay was 6 hours. No major complications were encountered and acceptance by patients and parents was excellent. Only 16 children who were not scheduled to do so needed to stay in hospital overnight. Recommendations to establish and improve day-stay surgical services are presented. It is concluded that a practical, efficient service can be established and that the authorities should be encouraged to expand appropriate facilities.

Ambulatory Surgical Procedures↗
PubMed1993

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Ambulatory Surgical Procedures↗
PubMed1991

Longitudinal assessment of changes in reproductive hormones during normal pregnancy.

The concentrations of hormones measured in serum from maternal blood change dramatically during pregnancy. While the relative contributions of sex steroids shift from maternal ovaries and adrenals to the fetoplacental unit, other maternal tissues such as pituitary and liver respond to increasing concentrations of estrogen and secrete increasing amounts of prolactin and sex-hormone-binding globulin. To determine longitudinal changes in circulating maternal hormones, we collected blood from 60 women on three occasions during their pregnancies. We observed a 1.7-fold increase in testosterone concentration in serum; concentrations of sex-hormone-binding globulin in serum rose 5.6-fold. The major increase (6.8-fold) in estradiol in serum occurred within the first 16 weeks, followed by a further 4.8-fold increase by term. Mean concentrations of progesterone, 17-hydroxyprogesterone, and androstenedione in serum increased 11.9-, 3-, and 1.3-fold, respectively, whereas concentrations of dehydroepiandrosterone sulfate (DHEAS) fell by 50%. Mean serum prolactin concentrations increased 3.8-fold during the first trimester and by a similar amount during the final 24 weeks of pregnancy. We used these data, obtained from a cohort of women with uncomplicated pregnancies, to construct reference intervals for hormones in maternal serum.

Androgens↗
PubMed1990

Severe oxprenolol poisoning: the importance of glucagon infusion.

We describe a case of severe oxprenolol poisoning (8 g overdose) where restoration of normal blood pressure depended critically on high-dose glucagon infusion after several bolus injections of glucagon had failed. We stress the importance of infusion delivery of glucagon in severe beta-blocker poisoning.

Adult↗
PubMed1988

Experimentally induced ileal ulcers in rats. A model to study non-specific inflammatory bowel disease.

A surgical technique was used to establish chronic intestinal ulcers in Sprague-Dawley rats. A 2-cm-long segment of the distal ileum was excised and left attached on the mesentery. The ileum was reanastomosed. The excluded ileal segment formed a 'cyst' of various sizes. Initially, the anastomoses healed well, but after 6-8 weeks para-anastomotic ulcers developed in more than 50% of the rats. Histopathology showed a chronic inflammatory reaction with a predominance of mononuclear cells and increased numbers of eosinophilic granulocytes. The surface of the ulcers was covered with bacteria. Penetrating ulcers with fistula formation occurred. It is concluded that this experimental model may be useful for time sequential studies of the development of chronic and ulcerative ileitis. It may also be used to study the effect of medical and surgical regimens for the treatment of non-specific chronic inflammatory bowel disease.

Animals↗
PubMed1987

Delayed neck infection following anterior spine surgery.

Pharyngoesophageal perforation and neck abscess formation is a rare complication of anterior cervical spine surgery. This complication usually manifests itself within the early postoperative period and is associated with soft tissue trauma at the time of surgery. We describe two cases of retropharyngeal abscesses and persistent pharyngocutaneous fistulae which occurred in a delayed fashion several months after cervical spine surgery. The etiology, diagnosis, and treatment of this problem is discussed with a review of the current literature.

Abscess↗
PubMed1986

The effects of ethane dimethane sulphonate (EDS) on bilaterally cryptorchid rat testes.

A single dose of ethane dimethane sulphonate (EDS) given to adult male rats has a specific destructive effects on Leydig cells, which are removed from the intertubular area by macrophages. This is associated with a decrease in testosterone (T) and a rise in serum FSH and LH for 21-28 days after EDS. Recovery of Leydig cells occurs from connective tissue precursors. This study uses the bilaterally cryptorchid rat to investigate the influence of local factors from the seminiferous tubules on the restoration of Leydig cell morphology and function. Morphometric data of intertubular tissue, hCG binding, serum T, FSH and LH levels all indicate that the Leydig cell population in cryptorchid testes is more rapidly restored from connective tissue cells when compared to the normal situation. The precise mechanism for this faster recovery will require further study.

Animals↗