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Biomedical subjects

P Doyle

Publications and source records attributed to P Doyle.

At least 55 records · Page 3Linked to original sources
PubMed1998

Cardiac tamponade from central venous catheters.

BACKGROUND: This retrospective study was undertaken to determine the mechanism by which cardiac tamponade (CT) occurs after placement of central venous catheters (CVC), and to determine if physicians are aware of this potentially lethal complication. MATERIALS AND METHODS: Twenty-five previously unreported cases of CT from CVC were reviewed. The chest radiographs and postmortem records were reviewed when available. Two hundred physicians were interviewed about their knowledge of CT from CVC. They were specifically asked if they had reviewed the three-volume video, "CVC Complications," that was sent by the Food and Drug Administration to all hospitals where CVC are inserted. RESULTS: All postinsertion chest radiographs showed the tip of the catheter to be within the pericardial silhouette. All patients developed unexplained hypotension from hours to 1 week after CVC placement. Eight patients complained of chest tightness, 12 of shortness of breath, and 15 were noted to have air hunger. The electrocardiogram showed inferior wall injury in 7 patients. None of the physicians surveyed had seen the FDA video. CONCLUSIONS: Cardiac tamponade from central venous catheters is preventable if the tip of the catheter is outside the cardiac silhouette on chest radiograph. Any patient with a CVC in place who develops unexplained hypotension, chest tightness, or shortness of breath should have an emergency echocardiogram to rule out cardiac tamponade.

Adolescent↗
PubMed1997

Spontaneous abortion in dry cleaning workers potentially exposed to perchloroethylene.

OBJECTIVES: To investigate the association between spontaneous abortion and work within dry cleaning units in the United Kingdom where the solvent perchloroethylene is used. METHODS: A retrospective occupational study of reproductive outcome in 7305 women aged 16 and 45 years, who were currently or previously employed in dry cleaning or laundry units in the United Kingdom. Data on workplace exposures and reproductive outcome were obtained by postal survey. A sample of reported spontaneous abortions was validated from medical records. Machine operator versus non-operator was used as a surrogate for exposure to perchloroethylene in dry cleaning units as no data on individual doses were available for women in this study. RESULTS: The response rate was higher for current workers of dry cleaning units (78%), than for past workers of dry cleaning units (46%). Similarly, the response for current laundry workers (65%) was higher than that for past laundry workers (40%). Overall, the reproductive characteristics of the respondents were similar to expectation. Examination of exposure at the time of pregnancy, however, showed that the rate of spontaneous abortion varied according to the type of work the women did during the pregnancy or in the three months before conception: being lowest for pregnancies not exposed to either dry cleaning or laundry work (10.9%), higher for those exposed to laundry work (13.4%), and higher still for those exposed to dry cleaning work (14.8%). Within the group of pregnancies exposed to dry cleaning, the proportion was higher if the woman reported that she worked as an operator at the time of the pregnancy (17.1%) rather than as a non-operator (11.6%). Adjusted odds ratios for the period 1980-95 showed that the risk was over 50% higher in operators than non-operators (p = 0.04). The physical demands of the two jobs are likely to be similar. A higher risk was found when work as a dry cleaning operator was compared with no work in either dry cleaning or laundry units during pregnancy. Exposure to dry cleaning as a non-operator was not associated with any excess risk. CONCLUSIONS: Women who worked in dry cleaning shops at the time of their pregnancy or in the three months before who described themselves as operators were about half as likely again to report that their pregnancy ended in a spontaneous abortion than women who described themselves as non-operators.

Abortion, Spontaneous↗
PubMed1997

Intra-articular hip arthrodesis without subtrochanteric osteotomy in adolescents: technique and short-term follow-up.

Twenty-five patients, 11 to 19 years in age, were treated with hip arthrodesis for an incapacitating painful and stiff hip. Clinical diagnoses included avascular necrosis (AVN) associated with slipped capital femoral epiphysis (SCFE) (7 patients), posttraumatic AVN (6), septic arthritis (4), complication of treatment of developmental dysplasia of the hip (DDH) (4), pathologic fracture of femoral neck through bone cyst with resulting AVN (2), Perthes disease (1), and idiopathic chondrolysis (1). Preoperative motion was minimal or absent in 13 patients, limited in 12, and very painful in 23 patients. A two-incision surgical approach was utilized, providing for an intra-articular fusion technique and internal fixation with precise positioning. The surgical technique described avoids any dissection of the hip abductor musculature or a deforming osteotomy of the proximal femur. Twelve complications occurred in 10 patients, 9 of which required additional operative treatment. At an average postoperative follow-up of 6 years, 10 months, the overall activity level was greatly increased over the preoperative activity level secondary to the relief of pain. Hip arthrodesis is the acceptable salvage procedure for the otherwise healthy, active adolescent or young adult with unilateral hip disease characterized by incapacitating pain and/or an unacceptable fixed position.

Adolescent↗
PubMed1996

Intracerebroventricular administration of neuropeptide Y to normal rats increases obese gene expression in white adipose tissue.

The aim of this work was to determine the possible inter-relationship between neuropeptide Y (NPY, a hypothalamic stimulator of feeding) and adipose tissue expression of the ob protein (a novel potent inhibitor of feeding). Such a relationship could be of importance in the maintenance of normal body weight. To this end, normal rats were intracerebroventricularly (i.c.v.) infused for 6 days with NPY. NPY infusion resulted in hyperphagia and a marked increase in adipose tissue ob mRNA levels. The effect of NPY on ob expression persisted when hyperphagia was prevented by pair-feeding, and was reversed following cessation of NPY infusion. Basal and glucose-stimulated insulinaemia were increased by i.c.v. NPY infusion compared to control values, regardless of whether animals were ad libitum-fed or pair-fed. Cessation of NPY infusion was accompanied by normalisation of insulinaemia. These changes in insulinaemia produced by i.c.v. NPY infusion paralleled the observed changes in ob expression. When normal rats were made hyperinsulinaemic-euglycaemic for 24 h, such hyperinsulinaemia also resulted in increased ob mRNA levels in white adipose tissue. This suggested that NPY-induced hyperinsulinaemia could be responsible for the upregulation of ob mRNA levels of NPY-infused rats. It is concluded that central (i.c.v.) NPY infusion increases adipose tissue ob expression, a functional relationship that is linked, at least in part, via NPY-induced hyperinsulinaemia.

Adipose Tissue↗
PubMed1996

Blood flow changes in the ovarian and uterine arteries during the normal menstrual cycle.

OBJECTIVE: Our purpose was to study the hemodynamic changes in the uterine and intraovarian vessels during the normal menstrual cycle and to relate the vascular changes to hormonal index values. STUDY DESIGN: Seven women who had bilateral tubal patency, a normal pelvis on laparoscopy, and regular ovulatory cycles underwent serial transvaginal ultrasonography on menstrual cycle day 2, daily from estimated day of ovulation-6, hourly from estimated day of ovulation-2, or when the mean follicular diameter was > 16 mm (whichever was earlier) until 6 hours after follicular rupture and once 7 days after follicular rupture. At each scan uterine and intraovarian blood flow was assessed with transvaginal color Doppler ultrasonography and serum concentrations of follicle-stimulating hormone, luteinizing hormone, estradiol, and progesterone assessed by fluoroimmunoassay. RESULTS: In one case there was evidence of a luteinized unruptured follicle and the patient was therefore excluded from analysis. In the other six women there was spontaneous ovulation at a mean of 39 hours after the onset of the luteinizing hormone surge. On the side with the dominant follicle, follicular and ovarian stromal peak systolic blood flow velocity rose significantly during the menstrual cycle with no significant change in pulsatility index. The changes in blood flow velocity correlated significantly with changes in serum follicle-stimulating hormone, luteinizing hormone and progesterone concentrations. There were no significant changes in either blood flow velocity or pulsatility index in the contralateral ovary. Uterine artery time-averaged maximum velocity on the side of the developing ovarian follicle increased during the menstrual cycle with no significant change in the contralateral vessel. Uterine artery pulsatility index on the side of the developing follicle declined during the midluteal phase and was significantly lower than on the contralateral side. The changes in time-averaged maximum velocity correlated with the changes in serum estradiol and progesterone concentrations. CONCLUSION: The vascular changes in the wall of the dominant ovarian follicle and ovarian stroma during the menstrual cycle are consistent with activity of angiogenic-like factors. The decline in uterine artery resistance during the midluteal phase may reflect optimal vascularity for implantation of the blastocyst.

Adult↗
PubMed1996

The outcome of multiple pregnancy.

The incidence of multiple pregnancy and delivery has increased dramatically over the past 10-15 years in many developed countries of the world. Data for England and Wales show that between 1980 and 1993 the twin maternity rate increased by approximately 25% and the triplet and higher order maternity rate more than doubled. Similar trends have been reported elsewhere. The majority of these increases have been linked to the use of ovarian stimulants and assisted reproduction techniques, and multiple pregnancy must be considered to be one of the most important adverse outcomes in current methods of infertility treatment. Obstetric complications associated with multiple pregnancy include prenatal screening problems and increased incidence of pregnancy-induced hypertension, antepartum haemorrhage, preterm labour and assisted or surgical delivery. Neonatal problems include low birthweight and increased prevalence of congenital malformations. Compared with singletons, neonatal mortality was seven times higher in twins and > 20 times higher in triplets and higher order births in England and Wales in 1991. Survivors also suffer higher rates of cerebral palsy and other neurological impairments. Most studies of pregnancies and babies resulting from assisted reproduction have demonstrated similar, if not higher, risks of adverse obstetric and neonatal outcomes for multiple births compared with national expectations. A poorer outcome in multiple pregnancy, especially in triplet and higher order pregnancy, supports the replacement of two good quality embryos in assisted reproduction treatment cycles.

Female↗
PubMed1996

Associations between ultrasound indices of follicular blood flow, oocyte recovery and preimplantation embryo quality.

The aim of this study was to elucidate possible relationships between ultrasound indices of follicular blood flow, oocyte recovery and the subsequent production and morphological quality of preimplantation embryos. A total of 27 women with bilateral tubal occlusion, undergoing treatment for infertility by in-vitro fertilization and embryo transfer, contributed data from 29 cycles. Transvaginal ultrasonography with colour Doppler imaging and pulsed Doppler spectral analysis was used to obtain indices of blood flow for each follicle immediately before it was aspirated. The main outcome measures for each follicle were the pulsatility index, peak systolic velocity, recovery or non-recovery of an oocyte and the subsequent production or non-production of an embryo. A total of 126 follicles were studied, 102 oocytes were recovered and 58 embryos (49 at grades I or II) were produced. There were six clinical pregnancies (pregnancy rate 27.3% per embryo transfer, 22.2% per patient). There was a significant correlation (P < 0.0001, chi2 test) between whether or not follicular blood flow was detected and whether or not an oocyte was recovered. The sensitivity of a test based on the presence of detectable blood flow and the subsequent recovery of an oocyte was 74% and the positive predictive value was 93%. The peak systolic velocity (PSV, measured in cm/s, mean +/- SD) in follicles with detectable blood flow was significantly higher in follicles that were associated with the production of a preimplantation embryo (19.7 +/- 10.8) compared with those that were not (9.9 +/- 5.3, P < 0.0001, Student's t-test). There was a 70% chance of producing a grade I or II embryo if the follicular blood velocity was >/=10 cm/s, compared with 14% if the PSV was <10 cm/s, or 18% if no blood flow was detected. We conclude that there is a physiological relationship between follicular blood velocity, oocyte recovery and the production of a high-grade preimplantation embryo, which may form the basis of a useful clinical test.

Adult↗
PubMed1996

Health of children born to medical radiographers.

OBJECTIVES: To develop a reliable method for collecting information on reproductive outcome in an occupational setting; and to investigate the health of children born to medical radiographers. METHODS: The study population comprised 6730 members of the College of Radiographers who were, at the time of survey; aged between 30 and 64 years, on the current membership file of the College, and were resident in Britain. RESULTS: The postal method developed proved to be reliable, with around 87% of questionnaires being returned. The observed frequencies of reproductive events were broadly in line with findings from other studies: of the 9208 pregnancies reported, 83% were livebirths, 12% were miscarriages (gestational age < 20 weeks), 1% were stillbirths (gestational age > or = 20 weeks), and 1% were other rarer spontaneous adverse events (ectopic pregnancy, blighted ovum, and hydatidiform mole). There was little difference between men and women in the frequency of adverse reproductive events reported, with the exception that male radiographers reported fewer medical terminations, the proportions being 3.1% and 1.4% for women and men respectively. Among children, the overall risks of major congenital malformation (RR 1.0, 95%CI 0.9-1.2), chromosomal anomaly (RR 1.4, 95%CI 0.8-2.3), and cancer (RR 1.2 95%CI 0.7-2.0) were as expected based on general population rates. Borderline excesses of chromosomal anomalies other than Down's syndrome in the children of female radiographers (RR 3.9, 95%CI 1.3-9.0, based on five observations), and cancer in the children of male radiographers (RR 2.7, 95%CI 0.9-6.5, based on five observations) were noted. The numbers on which these risks are based are small and the findings should be interpreted cautiously. CONCLUSIONS: The postal methods developed for obtaining information about reproductive events and child health proved to be reliable in men, as well as in women. Overall, the findings for medical radiographers are reassuring. Dose-response relations could not, however, be examined as long term dose records of radiographers are not routinely kept in an accessible form.

Abnormalities, Radiation-Induced↗
PubMed1996

Uretric obstruction in Gardener's syndrome.

Desmoid tumours in Gardener's syndrome are a rare cause of ureteric obstruction. We report two cases of ureteric obstruction caused by desmoids, in a mother and daughter.

Adult↗
PubMed1996

Bronchopulmonary dysplasia and corticosteroid therapy: a case review.

The use of corticosteroids as a treatment for chronic lung disease is increasing in newborn intensive care units. The anti-inflammatory mechanism of steroids suppresses the pulmonary inflammatory response, leading to improved pulmonary compliance and often a successful extubation. However, side effects, including sepsis, hypertension, glucosuria, and heme positive stools, have been reported. Caregivers must appreciate the multisystem biochemical effects of corticosteroids and anticipate the potential side effects when administering this medication. The article reviews the biochemical processes of dexamethasone, a synthetic corticosteroid, and presents a case study of an infant receiving dexamethasone. A question-and-answer format is interpolated throughout the case study and is intended to challenge the reader's knowledge of the pathophysiology of chronic lung disease and the biochemical actions of corticosteroids. Implications for nursing assessment and management of infants receiving this medication are reviewed.

Anti-Inflammatory Agents↗
PubMed1995

Four-day hyperinsulinemia in euglycemic conditions alters local cerebral glucose utilization in specific brain nuclei of freely moving rats.

Although insulin is a well known regulator of peripheral tissue glucose metabolism, there is little agreement over its effects on brain glucose metabolism. Several investigators report that peripheral insulin may enter the brain via several routes. The presence of insulin receptors specific to brain, coupled to diverse reports of the effect of acute insulin administration on brain glucose use, led us to carry out a 4-day hyperinsulinemic euglycemic clamp in freely moving rats with subsequent labelled 2-deoxyglucose metabolic mapping studies. It was found that after 4 days of peripheral insulin infusion, several brain regions (Anterior Hypothalamic area, Suprachiasmatic nucleus, Basolateral Amygdaloid nucleus, Supramammillary bodies, Medial Geniculate nucleus and Locus Coeruleus) had an altered local cerebral glucose utilization. Upon subsequent analysis of their anatomical and functional connections it is proposed that insulin may regulate an integrated circuit of pathways within the central nervous system.

Animals↗
PubMed1995

Assessment of fetal compromise by Doppler ultrasound investigation of the fetal circulation. Arterial, intracardiac, and venous blood flow velocity studies.

BACKGROUND: Doppler studies of the fetal circulation in intrauterine growth retardation and hypoxia have demonstrated a compensatory redistribution of arterial blood flow with increased flow to the cerebrum and myocardium and decreased flow to the periphery. The aim of this study was to evaluate the significance of changes in fetal venous blood flow waveforms in high-risk pregnancies and to investigate the time relation between alterations in venous and arterial Doppler waveform indices in compromised fetuses. METHODS AND RESULTS: The cross-sectional study consisted of 108 high-risk singleton pregnancies between 23 and 42 weeks' gestation without fetal chromosomal abnormalities or major malformations. Blood flow velocity waveforms were recorded from the umbilical arteries, descending thoracic aorta, middle cerebral artery, tricuspid and mitral ventricular inflow, ductus venosus, inferior vena cava, and the right hepatic vein. The mean velocity and pulsatility index were calculated for arterial vessels, the E/A ratio for atrioventricular blood flow, and peak forward velocities during ventricular systole and early diastole, the lowest forward velocity or peak reverse velocity during arterial contraction, and time-averaged maximum velocity for venous vessels. Two ratios for venous waveforms, one of which is the equivalent of the pulsatility index, were calculated. Fetal biophysical assessment was based on a computerized cardiotocogram and the biophysical profile score. The compromised group consisted of 37 fetuses delivered by cesarean section for an abnormal heart rate trace (n = 21) or severe preeclampsia (n = 9) or which died in utero (n = 7) within 10 days of their last Doppler investigation. This group showed significant alterations in arterial and venous flow velocity waveforms but not in atrioventricular inflow. Additionally, to find out whether venous Doppler investigation may help to detect a worsening of the situation in fetuses already showing arterial blood flow redistribution, we analyzed the data of these fetuses separately. The 41 fetuses that had an aorta/middle cerebral artery pulsatility index ratio > 95th percentile were divided into compromised and non-compromised groups according to their biophysical assessment and whether or not they developed fetal distress (cesarean section for abnormal heart rate trace or intrauterine death). The mean values for Doppler parameters of the compromised groups differed significantly from the noncompromised groups in all venous vessels, whereas differences on the arterial side were much less pronounced. Velocity ratios of venous waveforms were significantly higher, and absent or reverse flow in the ductus venosus with atrial contraction indicated a poor prognosis, with a perinatal mortality of 5 out of 8. CONCLUSIONS: Fetal compromise is associated with significant alterations in the fetal arterial and venous circulation. Significant changes in venous Doppler waveforms develop due to increased afterload and perhaps myocardial failure in late deterioration after fetal arterial redistribution is established and seem to be closely related to abnormal biophysical assessment findings. Therefore, Doppler investigation of the fetal venous circulation may play an important role in monitoring the redistributing growth retarded fetus and thereby may help to determine the optimal time for delivery.

Arteries↗
PubMed1995

In vitro and in vivo evaluation of the subtype-selective muscarinic agonist PD 151832.

PD 151832 is a potent partial muscarinic agonist that displays a high level of functional selectivity for the muscarinic m1 receptor subtype, as evidenced by its selective stimulation of PI turnover and cellular metabolic activity in transfected Hm1-CHO cells at concentrations that produce minimal stimulation of other cloned human muscarinic receptors. PD 151832 enhanced the amplification of Hm1-transfected NIH-3T3 cells at concentrations lower than those required to produce similar effects in Hm2 or Hm3-transfected cells. The functional m1 selectivity of PD 151832 is consistent with its improvement of mouse water maze performance at doses far lower than those required to produce peripheral parasympathetic side effects.

3T3 Cells↗
PubMed1995

The ob gene and insulin. A relationship leading to clues to the understanding of obesity.

Obesity and non-insulin-dependent diabetes are estimated to affect millions of people in the world. This pathology is multifactorial, comprising complex interactions of genetic and environmental factors and lacking a specific therapy. Great interest arose from the recent discovery of the ob gene expressed only in adipose tissue and coding for a protein that appears to regulate adiposity, potentially by acting as a satiety factor. We report here that in normal rats, ob mRNA is respectively up- or downregulated by a rise in insulinemia (induced by 2-day insulin infusion while maintaining euglycemia) or a decrease in insulinemia (induced by a 3-day fast). Our results also show that in genetically obese fa/fa rats studied longitudinally, white adipose tissue ob mRNA levels increase in parallel with early occurring and steadily increasing hyperinsulinemia. This results in adult obese animals having markedly higher ob mRNA levels than age-matched normoinsulinemic lean rats. Furthermore, in adult obese rats, ob mRNA escapes down-regulation as normalization of hyperinsulinemia due to fasting fails to reduce the high ob mRNA levels.

Adipose Tissue↗