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Biomedical subjects

P Lancaster

Publications and source records attributed to P Lancaster.

17 recordsLinked to original sources
PubMed2000

Incidence of cancer in children born after in-vitro fertilization.

Evaluation of the long-term health of children born using in-vitro fertilization (IVF) provides important information to clinicians and consumers. Until very recently, there have been no published data on the incidence of cancer in children conceived as a result of IVF, despite a number of case reports of neuroblastoma in children conceived using fertility drugs. This study used a record-linkage cohort design to investigate the incidence of cancer in children born after IVF. The study included all conceptions using assisted reproductive technologies between 1979 and 1995 at two clinics in Victoria, Australia that resulted in a live birth. Data on births were linked with a population-based cancer registry to determine the number of cases of cancer that occurred. The standardized incidence ratio (SIR) was calculated by comparing the observed number of cases to the expected number of cases. The final cohort included 5249 births. The median length of follow-up was 3 years, 9 months (range 0-15 years). In all, 4.33 cases of cancer were expected and six were observed, giving a SIR of 1.39 (95% CI 0.62-3.09). This study found that children conceived using IVF and related procedures did not have a significantly increased incidence of cancer in comparison to the general population.

Birth Weight↗
PubMed1999

Obstetric profiles and perinatal mortality among Pacific Island immigrants in New South Wales, 1990-93.

OBJECTIVES: To describe the obstetric profile and perinatal mortality of Pacific Island-born women giving birth in New South Wales (NSW) and assess risk factors associated with the high perinatal death rate previously noted in this immigrant group. METHOD: Retrospective cohort study based on the Midwives Data Collection in NSW from 1990 to 1993. Births to 5,034 Pacific Island-born women were compared with births to 256,843 Australian-born women. RESULTS: Pacific Island-born women had fewer teenage pregnancies and were of an older age and higher parity. They were more likely to be married or in a de facto relationship and to present for antenatal care later in the pregnancy. The proportion of low birthweight and preterm birth was similar in the two groups but Pacific Islanders had a higher perinatal mortality rate (14.6/1,000 vs. 10.3/1,000, RR = 1.42, 95% CI = 1.13-1.54). Even at normal and high birthweights, infants of Pacific Island-born women were at greater risk of perinatal death. After adjusting for maternal factors (marital status, insurance status, parity and maternal age) Pacific Islanders were 30% more likely to have a perinatal death (OR = 1.30, 95% CI 1.07-1.54). CONCLUSIONS: Further analyses of the causes of perinatal death in Pacific Island-born women are needed so appropriate interventions can be implemented. IMPLICATIONS: The need for the design and evaluation of culturally specific services aimed at improving antenatal care attendance in Pacific Islanders is emphasised. Conventional risk assessment may not adequately predict adverse perinatal outcomes in all populations.

Adolescent↗
PubMed1994

An optimized method for routine HLA-B27 screening using flow cytometry.

Flow cytometry and monoclonal antibodies are promising tools for HLA-antigen detection. Previous approaches have been hampered by the lack of a carefully standardized system for calibration and sample analysis. A new system for HLA-B27 screening was developed using a FACScan flow cytometer, software for automated calibration and analysis, calibration beads, and the anti-HLA-B27-FITC/anti-Leu4-PE (CD3) monoclonal antibodies. The median fluorescence channel result for the HLA-B27-FITC signal of CD3+ T lymphocytes is compared to a decision marker. Values lower than this threshold are read as HLA-B27 negative and those above are recommended for retesting with the classic microcytotoxicity assay on the presumption of HLA-B27 positivity. The anti-HLA-B27 antibody reacts with all six HLA-B27 subtypes and shows a weaker binding to HLA-B7. The screening test results were compared with those from the microcytotoxicity assay for HLA-typing in studies involving several European centers. The observed sensitivity was 100% (95% Cl:98.6-100) and the specificity was 97.4% (95% Cl: 96.4-98.3). Other performance studies verified the reproducibility and reliability of results obtained with the screening system.

Anticoagulants↗
PubMed1993

Monitoring dominant germ cell mutations using skeletal dysplasias registered in malformation registries: an international feasibility study.

Using data from seven malformation monitoring systems around the world, the feasibility of monitoring fresh dominant mutations using skeletal dysplasias was explored. Based on a total of over 9.5 million births, 1500 infants with skeletal dysplasias were identified (16 per 100,000). In spite of efforts to get exact diagnoses, an average of 21% were unspecified. Comparisons of rates of specific diagnoses in different programmes suggested that classification differed. By analysing maternal age distribution, estimates were made of the proportion of fresh mutations in different subgroups: conditions regarded as dominant (achondroplasia, thanatophoric dysplasia, spondyloepiphyseal dysplasia) were estimated to consist of 58% fresh mutations--some of the remaining cases were inherited, others were probably misclassified. Among conditions regarded as recessive, only 5% were estimated to be truly dominant mutations. In the total group of skeletal dysplasias, 21% were estimated to be fresh dominant mutations and if osteogenesis imperfecta were excluded, the figure was 31%. By power analyses it was shown that equal monitoring power may be obtained by a programme covering about 45,000 births per year with intensive diagnosis of each individual case of skeletal dysplasia and a programme some three times greater where no specific diagnoses are obtained. An increasing trend in the occurrence of skeletal dysplasias was seen but probably explained by changing ascertainment. An impact of antenatal diagnosis resulting in a decrease in occurrence was also apparent in some programmes.

Adult↗
PubMed1993

A technique for the laboratory determination of recirculation in single needle dialysis.

Recirculation is an important factor in single needle dialysis and, if high, can compromise treatment efficiency. To provide information regarding recirculation characteristics of access devices used in single needle dialysis, we have developed a new technique to characterise recirculation and have used this to measure the recirculation of a Terumo 15G fistula needle and a VasCath SC2300 single lumen catheter. The experimentally obtained results agreed well with those established clinically (8.5 +/- 2.4% and 18.4 +/- 3.4%). The experimental results have also demonstrated a dependence on access type, pump speeds and fistula flow rate. A comparison of experimental data with theoretical predictions showed that the latter exceeded those measured with the largest contribution being due to the experimental fistula.

Arteriovenous Shunt, Surgical↗
PubMed1991

Cough intensity in patients with a vocal cord palsy.

This study assesses the effect a paralysed cord has on the intensity of coughing. The air flow pattern during coughing of 10 patients with a vocal cord palsy was compared with a control group, using a computerized pneumotachograph system. There was no significant difference in the value of the peak air flow but the time taken to reach the maximum value was prolonged in the vocal cord palsy group. This non-invasive test may aid diagnosis of vocal cord palsies but the laterality of the lesion cannot be predicted from the airflow pattern alone.

Adult↗
PubMed1991

The effect of frequency on combined glottography.

This study investigates the relationship between frequency and the open quotient (OQ) and speed quotient (SQ) values of combined glottography. Simultaneous electroglottography and photoglottography were performed on 20 healthy male subjects. Regression analysis showed that neither OQ nor SQ was dependent upon frequency. The technique is therefore still valid despite the inability to control this variable.

Adult↗
PubMed1991

The effect of intensity on combined glottography.

This study investigates the relationship between intensity and the open quotient (OQ) and speed quotient (SQ) values of combined glottography. Simultaneous electroglottography and photoglottography were performed on 20 healthy male subjects at intensities of 55 and 65 dB. Paired t-test statistical analysis showed that the open quotient varies inversely and the speed quotient directly with the intensity. When reporting findings it is therefore necessary to state the intensity at which the results were obtained.

Adult↗
PubMed1991

Cough intensity in the laryngectomee.

The exact role or even the necessity for a functioning larynx in the production of an efficient cough is unknown. This study compares the cough intensity of 10 laryngectomees with a control group of 10 individuals with a larynx. There is no significant difference in the peak flow but the time taken to reach the peak flow is prolonged in the laryngectomees. The supramaximal expiratory flow is thus absent. The larynx is not essential for coughing although the different pattern may be less efficient. This simple test may have diagnostic value in assessing the larynx.

Aged↗
PubMed1991

An outpatient clinic system for glottographic measurement of vocal fold vibration.

It has recently been suggested that combined electroglottography and photoglottography may aid diagnosis and assessment of treatment of laryngeal pathology. The ability to record and analyse such traces was previously restricted to voice research laboratories. A simple, less expensive, system for use in the outpatient clinic is described. A preliminary study on 10 normal subjects produced results comparable to that of voice research laboratories. The clinical potential is discussed. This may represent a valued addition to the armamentarium of the clinician.

Electrophysiology↗
PubMed1989

The wider perinatal significance of the Australian in vitro fertilization data collection program.

The most recent report (1986) from the Australian Register of In Vitro Fertilization pregnancies comprises 2242 in vitro fertilization (IVF) pregnancies and 261 gamete intrafallopian transfer (GIFT) pregnancies. A review of this data base indicated that this population had a relatively high incidence of both obstetric and perinatal morbidity and perinatal mortality. About 58% of the IVF pregnancies resulted in live births and 36.4% of the infants weighted less than 2500 gm at birth. These high rates could be partially accounted for by maternal prepregnancy risk factors, such as age, and by risk factors associated with the infertility management, such as multiple pregnancy (22% of all pregnancies more than 20 weeks), which accounted for approximately 50% of the preterm births (less than 37 weeks). Singleton pregnancies also had a higher incidence of preterm birth (17.8% at gestational age 24 to 36 weeks), low-birthweight babies (15.9% less than 2500 g) and perinatal mortality rates (35.4% per 1000 live births) than the Australian population at large. This warrants these patients being regarded as high risk. It is reassuring that the incidence of major malformations in IVF births (2.2%) is similar to that in the general population (1.4%).

Australia↗
PubMed1975

Smoking and pregnancy.

Smoking is associated with decreased fertility in both males and females, an increased abortion rate, lowered birth weight, an increased still birth rate and probably an increased neonatal death rate. There is also a reduced incidence of maternal hypertension (although the babies are at even greater risk), an increased incidence of ante-partum haemorrhage, impaired brain development and possible teratogenic effects. These effects can be reversed if the mother gives up smoking in pregnancy.

Animals↗
PubMedDate not supplied

An international collaborative study of the epidemiology of esophageal atresia or stenosis.

Epidemiologic data were analyzed for a total of 2,693 infants with esophageal atresia registered in nine congenital malformation registries around the world. The average recorded prevalence at birth was 2.6 per 10,000 births, with a significant variability among programs--and sometimes within a program--and a maximum prevalence of above 3 per 10,000 births. Clusters of infants with esophageal atresia were observed but may be random. An increasing rate was seen during the period 1965 to 1975 (Norway, South America, Sweden). The type of esophageal atresia was specified in only 439 cases, but no major differences were seen in the epidemiologic characteristics of infants with the most common type (distal fistula) and infants with other types. There was an excess of low birth weight and preterm birth, and infants with esophageal atresia had a birth weight 500 to 1,000 g less than normal infants in each gestational week. There was an excess of twins, apparently mainly or exclusively due to monozygotic twinning, but in only two pairs did both twins have esophageal atresia. There was no effect seen of maternal age, but low parity, irrespective of maternal age, was associated with an increased risk for esophageal atresia. Infant survival varied among programs and depended heavily on associated malformations. Among 1,107 sibs born before the proband and 385 born after the proband, only 25 (1.7%) had a serious malformation; three had esophageal atresia. In 57.3% of the infants with esophageal atresia, no other malformations were present, in 36.4% other major malformations were recorded, and in 6.3% there were chromosomal anomalies. The malformations present associated with esophageal atresia were analyzed: a large proportion entered the constellation sometimes called "caudal mesoderm spectrum of malformations": VATER, Potter, and caudal regression sequences.

Birth Weight↗