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Biomedical subjects

C Dezateux

Publications and source records attributed to C Dezateux.

51 records · Page 3Linked to original sources
PubMed1997

Determination of antimony in urine, blood and serum and in liver and lung tissues of infants by inductively coupled plasma mass spectrometry.

Methods are presented for the determination by ICP-MS of antimony in body fluids and tissues of infants. Urine, serum and whole blood specimens are prepared for analysis by simply diluting 200 microliters sample volumes (1 + 14) with water and adding indium as internal standard. Liver and lung tissues are digested using 16 M HNO3 either in open quartz vessels at 150 degrees C or in sealed vessels with microwave heating. The acid digests are diluted with water and indium is added as internal standard for ICP-MS measurements. All analyses were subjected to stringent internal quality control protocols. Accuracy was assessed by recoveries, repeated analyses and by analysis of NIST SRMs 1577a Bovine Liver and 1566a Oyster Tissue. Precisions of analyses were better than 5-10% in the ranges 0.1-0.3 microgram l-1 for urine, serum and blood; and at 7-25 ng g-1 in tissues. Detection limits were 0.7 ng g-1 in liver, 0.8 ng g-1 in lung, and 0.01 microgram l-1 in urine, serum and blood. The need to employ validated procedures for specimen collection and to give considerable attention to pre-analytical factors in order to avoid adventitious contamination with antimony is demonstrated.

Antimony↗
PubMed1997

Lung development and early origins of childhood respiratory illness.

In the last two decades, 5 cohort studies have been initiated to examine the association of infant respiratory function with genetic and environmental risk factors, as well as with subsequent lower respiratory illness in early childhood. While the current complexity of respiratory function tests in this age group precludes study samples with sufficient power to examine more complex issues, information from these studies has provided an exciting adjunct to that available from the longer cohort studies. Premorbid alterations in airway function or lung development increase the risk of wheezing lower respiratory illnesses during the preschool years and the risk of impaired airway function at 5-6 years of age. In addition, gender differences in airway function and the response to maternal smoking have been observed. Larger collaborative population-based studies are needed to explore the environmental, genetic and immunological mechanisms responsible, but will depend on the development of less invasive tests of airway function appropriate for use in healthy infants.

Adolescent↗
PubMed1997

Urinary antimony in infancy.

OBJECTIVE: To determine whether antimony may be detected in the urine during infancy and early childhood and its association with passive exposure to tobacco smoke, as assessed by urinary cotinine. DESIGN: Analysis of spare aliquots of urine collected from infants participating in studies of respiratory function and passive smoking. Urinary antimony was assayed using inductively coupled plasma mass spectroscopy in 201 urine specimens collected at different ages throughout the first two years of life from 122 term and 26 preterm infants. Urinary cotinine was measured using gas liquid chromatography. MAIN OUTCOME MEASURE: Urinary antimony concentrations. RESULTS: Absolute antimony concentrations varied widely between infants, being below the laboratory detection limit of 0.02 microgram/l in 7% of samples, below 0.5 microgram/l in 90.5%, and above the reference value of 1 microgram/l reported for non-occupationally exposed UK populations in 4%. Creatinine standardised antimony values were unrelated to postnatal age or urinary cotinine concentrations and were highest in urine collected from preterm infants within 24 hours of birth (geometric mean (95% confidence interval): 2.3 ng/mg (1.5 to 3.4)). CONCLUSIONS: Although antimony is present at very low concentrations in urine during infancy and early childhood, the relevance to health is uncertain. The higher levels found in preterm infants may reflect prematurity or fetal assimilation of antimony. Tobacco is unlikely to be an important source of environmental exposure to antimony during infancy and early childhood.

Aging↗
PubMed1997

Infant respiratory function after RSV-proven bronchiolitis.

The mechanisms underlying the increased risk of wheezing in early childhood following acute bronchiolitis in infancy remain unclear. Previous studies have reported significant abnormalities in infant respiratory function after clinical recovery from bronchiolitis, but are difficult to interpret because of the frequent omission of a concurrent comparison group. Respiratory function was compared within pairs of previously healthy full-term caucasian infants admitted with a first episode of acute bronchiolitis to an inner London hospital, and age- and sex-matched control infants without prior wheezing, asthma, or lower respiratory illness who were recruited from local general practices. Respiratory function was measured in 29 control and 29 asymptomatic index infants, with measurements in the latter done at a median interval of 36 wk (range: 16 to 49 wk) after admission, when 16 (55%) had experienced subsequent wheezing. Index infants tended to be autumn-born and of shorter gestation than control infants, to have younger mothers, and to have been exposed to tobacco smoke. There were no statistically significant differences in plethysmographic FRC, initial inspiratory airway resistance (Raw), or respiratory system compliance (mean [index minus control] within-pair difference [95% confidence interval]: -11 ml [-29, 7 ml]; -0.2 kPa/L/s [-0.7, 0.4 kPa/L/s]; -8 ml/kPa [-21, 4 ml/kPa], respectively), but respiratory rate and time to peak tidal flow as a proportion of total expiratory time (tPTEF:tE) were significantly diminished in index as compared with control infants (-4.0 breaths/min [-7.6, -0.4 breaths/min], versus -0.035 [-0.066, -0.005], respectively). These findings suggest a better prognosis for infant lung function after acute bronchiolitis than reported previously. Longitudinal studies are needed to clarify whether subclinical alterations in airway function precede acute bronchiolitis.

Acute Disease↗
PubMed1997

Influence of ethnicity and gender on airway function in preterm infants.

While maximal expiratory flow at functional residual capacity, calculated from partial expiratory flow volume curves (V'maxFRC), is a valuable measure of peripheral airway function in infants, limited data are available in preterm infants despite their high prevalence of respiratory problems. To investigate the influence of gender and ethnic group, V'maxFRC and other indices of respiratory function were measured in 28 black and 28 white preterm infants (50% female in each group) at time of discharge from the neonatal unit (mean [SD] weight 2.36 [0.3] kg, postnatal age 19 [9] d). No infant had any history of cardiorespiratory disease and all were born to non-smoking mothers. V'maxFRC tended to be higher in girls than boys (115 versus 94 ml.s-1 [95% CI: -5; 47]) but there was no significant difference in this parameter between black and white infants (111 versus 98 ml.s-1 [95% CI of difference: -12; 40]). Respiratory resistance (Rrs) was significantly lower in black than white infants (95% CI: -2.9; -0.4 kPa.L-1.s) and tended to be lower in female than male infants (95% CI: -2.3; 0.2 kPa.L-1.s). Similarly, time to peak tidal expiratory flow as a proportion of total expiratory time (tPTEF:tE) was significantly longer in black than white (95% CI: 0.06, 0.20) and in female than male (95% CI: 0.02, 0.15) infants. These findings suggest that certain parameters of airway function may be influenced by both ethnic group and gender in preterm infants, both of which should therefore be taken mw account when investigating the effects of disease and/or therapeutic interventions in this group.

Airway Resistance↗
PubMed1996

A national survey of screening for congenital dislocation of the hip.

OBJECTIVE: To identify current screening and management practices for congenital dislocation of the hip (CDH), and determine the extent to which ultrasound imaging of the hips is practised throughout the United Kingdom and the Irish Republic. METHODS: Postal questionnaire to paediatricians responsible for the routine neonatal care of infants in all maternity units in the UK and the Irish Republic. RESULTS: Questionnaires were returned for 254 maternity units (92% response rate). By 1994, 69% of maternity units had access to ultrasound imaging of the hips, compared to 14% in 1984. Ultrasound imaging of the hip was not used for universal primary screening, but in 93% of units was undertaken for further assessment of infants with clinically detected hip instability or those identified as being at high risk of CDH, or both. Clinical screening of newborn infants was performed by junior paediatricians, but training with a 'Baby Hippy' hip simulator model was provided in only 37% of units. Treatment of clinically detected hip instability, initiated by an orthopaedic surgeon in 93% of units, varied widely in type and duration. CONCLUSIONS: Ultrasound imaging of the hip is increasingly used in the UK for secondary, rather than primary, screening. Current recommendations are implemented to a variable extent nationally, and the existing wide variation in screening and management for CDH reflects a lack of research evidence to support current screening practices. The effectiveness of screening for CDH needs to be established.

Hip Dislocation, Congenital↗
PubMed1996

Validation of the reporting bases of the orthopaedic and paediatric surveillance schemes.

BACKGROUND: Nationally representative estimates of treatment rates for congenital dislocation of the hip were required to inform a review of the current United Kingdom screening policy. Cases were ascertained through an active reporting scheme involving orthopaedic surgeons and the existing British Paediatric Association Surveillance Unit (BPASU) scheme. OBJECTIVE: To report the methods used to establish, maintain, and validate the orthopaedic and BPASU schemes. METHODS: Multiple sources were used to develop the orthopaedic reporting base. Surgeons treating children were identified by postal questionnaire. The orthopaedic and paediatric reporting bases were compared to the 1992 manpower census surveys of surgeons and paediatricians. RESULTS: A single source of respondent ascertainment would have missed 12% of the 517 surgeons who treated children. Comparison with the manpower census data suggests the orthopaedic and paediatric reporting bases were 97% and 92% complete. CONCLUSIONS: Multiple sources should be used to establish and maintain a reporting base. Targeting respondents avoids unnecessary contact, saves resources, and may improve compliance. Manpower census data can be used for regular validation of the reporting base.

Child, Preschool↗
PubMed1996

Delayed maturation of Hering-Breuer inflation reflex activity in preterm infants.

We have previously shown that the strength of the Hering-Breuer inflation reflex (HBIR) diminishes between 2 and 12 mo of age in full-term babies. The purpose of this study was to determine whether the onset of this decline had commenced by 3 to 4 mo of age in healthy full-term infants and whether preterm delivery influences the pattern of maturation. Serial measurements of HBIR activity using the end-inspiratory occlusion technique were made in 25 preterm and 27 full-term infants at matched postnatal and postconceptional ages during the first 6 mo of life. Although similar levels of reflex activity were observed at birth (mean +/- SD of 101.2% +/- 42.4% in preterm, and 101.0% +/- 33.9% in full-term infants), by 40 wk postconceptional age (PCA) (i.e., term equivalent) HBIR activity (mean +/- SD) had increased to 121.7% +/- 51.2% in preterm infants, which was significantly greater than that in full-term infants of similar PCA (95% CI of difference: 0.2; 41.2%). By 15 wk postnatal age (PNA), HBIR activity had decreased to 68.8% +/- 26.6% in full-term infants, but remained significantly higher in those delivered prematurely (87.8% +/- 32.7%). However, when measurements were repeated at approximately 4 mo after the expected rather than actual date of delivery, these differences were no longer evident (95% CI difference preterm-full-term: -21.2; 3.8%). This study suggests that important transitions in respiratory control mechanisms occur between 8 and 15 wk PNA in full-term infants and that these changes are delayed in preterm infants.

Aging↗
PubMed1995

A critical assessment of uncalibrated respiratory inductance plethysmography (Respitrace) for the measurement of tidal breathing parameters in newborns and infants.

We have compared results obtained with an uncalibrated respiratory inductance plethysmograph (RIP) with those of a face mask and pneumotachograph (PNT) for the computerized measurement of the time to reach peak tidal expiratory flow as a ratio of total expiratory time (tPTEF:tE). Simultaneous measurements were made in 32 healthy neonates aged 0-3 weeks, 35 healthy infants aged 5-82 weeks, and 28 infants aged 15-94 weeks with physician diagnosed recurrent wheeze. The group mean (+/- SD) values of tPTEF:TE determined using a PNT were 0.455 (+/- 0.129), 0.263 (+/- 0.077), and 0.232 (+/- 0.089) for the neonates, healthy infants and infants with recurrent wheeze respectively. RIP gave mean (+/- SD) values that were 0.055 (+/- 0.044) and 0.025 (+/- 0.104) lower than the PNT in healthy neonates and infants with recurrent wheeze respectively; RIP values were 0.002 (+/- 0.073) higher in the healthy infants over 4 weeks of age than measurements by PNT. Although the difference between the two measurements was not related to the thoracoabdominal phase angle, as measured from Lissajous figures, examination of the RIP ribcage and abdominal signals revealed that many healthy subjects, while appearing clinically in phase, had ribcage and abdominal signals that differed markedly from each other in terms of convexity/concavity during early expiration. This may explain the lack of agreement between the two methods. We conclude that uncalibrated RIP should be used with caution for the determination of tPTEF:tE, even in subjects whose ribcage and abdomen appear to move synchronously. The measurement of tPTEF:tE did not differentiate between the healthy infants and infants with recurrent wheezing.

Data Interpretation, Statistical↗
PubMed1995

Evaluating the national screening programme for congenital dislocation of the hip.

In 1969 universal clinical screening for neonatal hip instability was formally adopted in the United Kingdom with the aim of detecting and treating children considered to be at high risk of congenital dislocation of the hip (CDH). However, clinical screening is associated with both false positive and false negative diagnoses and has never been evaluated in a randomised trial. The emergence of hip ultrasound provides renewed impetus to reconsider and formally evaluate screening for CDH. Ultrasound imaging of the newborn hip may be used as a screening test and to assess and manage infants with clinically detected hip instability. Universal primary ultrasound screening has been adopted in some European countries, but enthusiasm for this new technology has been tempered by the subsequent large increases in treatment and follow up. This paper reviews the existing evidence to support the different approaches to screening and describes the research agenda of the MRC working party on congenital dislocation of the hip. A randomised trial of screening is required to evaluate the policy options before ultrasound screening becomes widely adopted within the United Kingdom. The feasibility and acceptability of a trial need to be explored and key issues relating to trial design addressed.

Evaluation Studies as Topic↗
PubMed1991

The effect of triclofos sodium sedation on respiratory rate, oxygen saturation, and heart rate in infants and young children.

Chloral hydrate is frequently used to sedate infants for lung function testing. While no effect on respiratory function has been demonstrated, a recent study has reported a fall in oxygen saturation (SaO2) following sedation in wheezy infants. This study was designed to assess the effects of the closely related but less gastrically irritant drug triclofos sodium on respiratory rate (RR), heart rate (HR), and SaO2 in infants without cardiopulmonary disease. Paired measurements using respiratory inductance plethysmography and pulse oximetry were obtained in 10 infants (4-19 months of age) during natural and sedated sleep. Following sedation with triclofos, mean RR rose by 1.9 breaths min-1 (95% confidence intervals [Cl] of the mean difference: 0.13-3.7 min-1). Mean heart rate rose by 5.5 beats min-1 (95% Cl: -0.9-11.9 min-1). Mean SaO2 fell by 0.68% (95% Cl -1.8-0.45%). None of these changes are considered to be of clinical importance, and only the change in RR reached statistical significance at the 5% level.

Procedural Sedation↗
PubMed1984

Orofaciodigital syndrome with mesomelic limb shortening.

Two sisters, the children of first cousin Pakistani Moslem parents, have unusual facies, tongue hamartomata, pre- and postaxial polydactyly, severe talipes, and mesomelic limb shortening associated with tibial dysplasia. Homozygosity for a recessive gene defect is probable. The phenotype resembles, but is distinct from, the orofaciodigital syndromes delineated to date. We suggest that this condition be labelled OFD IV.

Abnormalities, Multiple↗