Search PubMed⌕ Search

Biomedical subjects

J Halliday

Publications and source records attributed to J Halliday.

67 records · Page 4Linked to original sources
PubMed1974

The effects of certain anaesthetic and anti-convulsant drugs on the CSF potassium fluxes of the dog.

1 A technique has been developed for open-ended perfusion of the cerebroventricular system of the unanaesthetized dog.2 Perfusion with an artificial CSF solution containing inulin and (42)K allowed the potassium fluxes out of and into the CSF to be monitored over a period of 2 to 3 hours.3 Sodium thiopentone and sodium pentobarbitone, in doses producing light anaesthesia, caused varying degrees of depression (up to 50%) in the CSF potassium fluxes, influx being consistently more affected than efflux. These effects are attributed to a decrease in the potassium exchange between extracellular and intracellular compartments in the brain.4 Diazepam depressed both potassium fluxes by up to 10% while there was some evidence that diphenylhydantoin depressed only potassium influx.5 Paraldehyde, in contrast to the other drugs, when given at a dose level sufficient to produce light anaesthesia, stimulated CSF potassium fluxes, particularly efflux.

Anesthetics↗
PubMedDate not supplied

Collaborative prospective study of the fragile X syndrome: one-year progress report.

A prospective study of the fragile X syndrome [fra(X)] was initiated one year ago to refine the estimates of recurrence risks based on the phenotype of the mother and the family history of the syndrome. The basic unit of data consists of the description of the conceptus of women known to carry the fra(X) gene or of mothers of an isolated case. To date, information on 261 women and their conceptuses was ascertained primarily through prenatal diagnosis; these data are summarized here. Although tests of significance were limited due to small sample sizes in subgroups, the following trends were observed: 1) the penetrance of fra(X) site expression was 80% in both male and female conceptuses suggesting that fra(X) site expression is equally penetrant early in development; 2) the sex ratio at the time of prenatal diagnosis did not differ from one, indicating that selection against fra(X) fetuses, if any, does not differ among sexes; 3) the recurrence risk among offspring of borderline/mildly retarded mothers was higher than that among offspring of intellectually normal mothers; 4) the recurrence risk in offspring did not differ based on the mother's fra(X) site expression; and 5) the recurrence risk in offspring of mothers with isolated cases was slightly less (34%) than that of obligate carrier mothers (41%) although this was not significant. The potential use of these prospective data on the fra(X) syndrome is emphasized.

Female↗
PubMedDate not supplied

Utilization of prenatal cytogenetic diagnosis in women of advanced maternal age in Australia, 1979-1982.

This paper reports the results of a complete national survey to measure utilization rates of prenatal cytogenetic diagnosis (P.C.D.) in women of advanced maternal age in Australia. P.C.D. has been available throughout Australia for the last decade. Every laboratory in Australia providing a P.C.D. service for the years 1979-1982 took part in this study. Utilization rates (both National and State rates) by ages of mothers, are presented. Big interstate differences exist. The 1982 National P.C.D. utilization rate for pregnant women who were 40 years of age and over was 38.8 per cent, and this rate has shown an average annual increase of 9 per cent. In those four States which offered P.C.D. to pregnant women of 35 years or over the median utilization rate was 20 per cent. These Australian rates indicate an under-utilization of P.C.D. services with (in 1982) 50-80 per cent of 'at risk' women not being tested. Factors which influence this are discussed.

Adult↗
PubMedDate not supplied

Use of community genetic screening to prevent HFE-associated hereditary haemochromatosis.

HFE-associated hereditary haemochromatosis is a recessive, iron-overload disorder that affects about one in 200 north Europeans and that can be easily prevented. However, genetic screening for this disease is controversial, and so we assessed whether such screening was suitable for communities. Cheek-brush screening for the Cys282Tyr HFE mutation was offered to individuals in the workplace. Outcomes were assessed by questionnaires before and after testing. 11,307 individuals were screened. We recorded no increase in anxiety in individuals who were homozygous for the Cys282Tyr mutation or non-homozygous. Self-reported tiredness before testing was significantly higher in homozygous participants than in non-homozygous participants (chi2 test, p=0.029). Of the 47 homozygous individuals identified, 46 have taken steps to treat or prevent iron accumulation. Population genetic screening for HFE-associated hereditary haemochromatosis can be practicable and acceptable.

Adult↗
PubMedDate not supplied

Validation study of the Victorian Birth Defects Register.

OBJECTIVE: To determine whether there has been an improvement in ascertainment of birth defects cases ('case validity') by the Victorian Birth Defects Register (BDR) since an earlier study (conducted in 1993), to ascertain the accuracy of registered data ('item validity') and to investigate another possible source of notification. METHODS: The medical records were reviewed of 500 children born after 1 January 1993 who were consecutively admitted after 1 January 1999 to two paediatric teaching hospitals in Victoria. In addition, records of 200 children referred to a clinical genetics service were reviewed for children born after 1 January 1993 and who were seen in two periods: 2 months after 1 January 2001 and 2 months after 1 January 2002. The records from the hospitals and clinical genetics service were reviewed separately to determine whether children recorded as having a birth defect had previously been notified to the BDR. RESULTS: Twenty percent of the hospital records related to a child with a birth defect, as did 70% of the clinical genetics service records. Overall case validity for birth defect cases from the hospitals was 88%. There was 100% ascertainment for three of five categories. Sixty per cent of birth defects cases from the clinical genetics service had been notified to the BDR. When all diagnoses in matched cases were considered, item validity was 54%, however, if only primary diagnoses were included then 92% of cases had the same diagnosis. CONCLUSIONS: Overall case validity from the two paediatric teaching hospitals has significantly improved since our previous study. The addition of an extra data source from a clinical genetics service would identify new cases, particularly genetic disorders and developmental delay, as well as adding new diagnoses to existing ones. This study has highlighted the need to improve item validity, perhaps through routine education for all coders and notifiers on the inclusion and exclusion of specific associated conditions when notifying major birth defects.

Age Factors↗
PubMedDate not supplied

Validation of the Victorian Perinatal Morbidity Statistics form: new items, pre-coded text and free text.

This study assessed the quality of information on the form used by the Victorian Perinatal Data Collection Unit. Information relating to four new and one modified data items, and to pre-coded and free text regions relating to maternal morbidity, was compared with that in the medical record. The new data items were documented correctly on 95.5% of forms, as were 67% of pre-coded conditions. Between 53% and 75% of free text items were correctly recorded. The results highlight the need for information and education sessions for midwives and other staff in order to collect and maintain high quality data.

Congenital Abnormalities↗
PubMedDate not supplied

The accuracy of eclampsia cases reported to the Victorian Inpatient Minimum Database and the Perinatal Data Collection Unit.

The aim of this study was to compare the quality of the reporting and coding of eclampsia in two routine data collections: the Victorian Inpatient Minimum Database (VIMD) and the Perinatal Data Collection Unit (PDCU). The validity of cases in the two data sets was confirmed by reference to the original medical record data. Only 12 cases were the same in both data sets (i.e., 35.3% agreement). There were an additional 51 cases that were reported to either one or the other of the data sets and, of these, only 15 (i.e., 29%) were confirmed as eclampsia. The overall number of cases confirmed for both systems in 1995 was 27, or 0.4 per 1000 confinements. Reasons for these discrepancies were investigated and three basic problems identified: quality of documentation in the medical record, coding errors, and use of data from computer-generated forms. Neither the VIMD nor the PDCU was regarded as having sufficiently accurate data for adequate reporting of maternal morbidity. By combining the information from both databases a better estimate of incidence can be obtained, but improved reporting and coding is essential for accurate assessment of this condition.

Adult↗