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Biomedical subjects

R W Smithells

Publications and source records attributed to R W Smithells.

At least 19 recordsLinked to original sources
PubMed1990

Delayed detection of congenital hearing loss in high risk infants.

OBJECTIVE: To examine the methods used to investigate children at high risk of congenital hearing impairment, and to see whether the introduction of evoked response audiometry has reduced the mean age at which hearing loss is identified. DESIGN: Clinicians who notified children to the national congenital rubella surveillance programme were asked retrospectively to complete a questionnaire examining the methods used to identify hearing impairment and the age at testing in two consecutive five year cohorts. The presence or absence of hearing loss was confirmed by obtaining the results of audiometric evaluations and, whenever possible, a recent pure tone audiogram. SETTING: The United Kingdom. PATIENTS: Children notified to the national congenital rubella surveillance programme and born in 1978-87 in whom IgM specific for rubella was detected shortly after birth. MAIN OUTCOME MEASURES: The age at which hearing loss was identified and the degree of loss in decibels at 250, 500, 1000, 2000, and 4000 Hz measured by pure tone audiometry. RESULTS: 61 (52%) Of 117 children born in 1978-82 had a hearing impairment of 40 dB or greater in both ears. The mean loss was 93 dB. In the following five years 75 (47%) of 159 children had impaired hearing, their mean loss being 96 dB. The age at which the hearing loss was confirmed decreased from 11.6 to 9.8 months as a result of earlier auditory evoked response testing. Nevertheless, only eight (13%) of the children with hearing impairment born in 1978-82 and 16 (21%) of those born in 1983-7 had these tests performed in the first six months of life. CONCLUSIONS: Unacceptable delays in identifying hearing loss occurred in this high risk group because of failure to arrange auditory evoked response testing in early infancy. Evoked response audiometry is sensitive and specific and should be undertaken within the first few months of life for all infants known to be at risk of sensorineural hearing loss.

Age Factors↗
PubMed1990

Multiple abnormalities in a child with partial duplications of 10p and 13q from a 3:1 segregation of a maternal t(10;13) translocation.

Partial duplications of 10p and 13q in association with partial deletions of other chromosome segments have been variously reported. We describe here a female child with multiple congenital abnormalities and combined partial duplications of 10p and 13q resulting from a 3:1 segregation of a maternal t(10;13)(p13;q22). In comparing the phenotypic features of the two chromosome imbalances, the expression of features typical of partial duplication 10p appeared more pronounced.

Abnormalities, Multiple↗
PubMed1989

A rapid and specific HPLC-electrochemical method for the determination of endogenous 5-methyltetrahydrofolic acid in plasma using solid phase sample preparation with internal standardization.

A rapid and specific HPLC-electrochemical method for determining endogenous 5-methyltetrahydrofolic acid (5MeTHF) in plasma is described. Quantitative solid phase extraction of 5MeTHF and internal standard, beta-hydroxyethyltheophylline, was carried out using proprietary phenyl bonded-silica columns (Bond Elut Phenyl cartridges, 1.0 mL capacity). Chromatographic separation was achieved using a mobile phase consisting of 15% (v/v) methanol in 0.05 M KH2PO4, pH 3.5 at a flow rate of 2.0 mL/min in conjunction with a Waters Assoc. radially compressed Nova-Pak phenyl column (10 cm x 8 mm, 4 microns bonded silica). The internal standard was measured by UV detection at 254 nm. A Bioanalytical Systems Inc. LC-17 glassy carbon oxidative flow cell with a potential held at +0.35 V vs Ag/AgCl using the LC-4A amperometric controller allowed levels of 1-2 ng/mL 5MeTHF to be measured in 500 microL of plasma. Daily appraisal of the ratio produced by authentic materials clearly demonstrated that quantitation using dual detection was not subject to problems of differential response. Inter-day variation of the differential detector response is cited. Comparison of the Lactobacillus casei bioassay with HPLC demonstrates good agreement between methods but at the same time highlights the drawback of using such non-specific methods to measure samples where more than one folylmonoglutamate may be present. Antoxidant free storage for three months at -70 degrees C in darkness resulted in no deterioration of 5MeTHF. A comparison of the means and range of values for plasma folate obtained using HPLC, L. casei bioassay and the radiometric binding assay is reported.

Chromatography, High Pressure Liquid↗
PubMed1989

In vivo characterization of the absorption and biotransformation of pteroylmonoglutamic acid in man: a model for future studies.

HPLC-EC has been used to measure the appearance of 5-CH3-H4 folic acid in human plasma following oral administration of folic acid. The process was found to be saturable in accordance with Michaelis-Menten kinetics. The apparent Km for this enzyme system indicates that low doses of oral folic acid are rapidly converted into 5-CH3-H4 folic acid, an observation consistent with the needs of intestinal absorption of essential trace nutrients. The appearance of L. casei active folate in plasma was not rate-limited and showed a biphasic relationship to dose. Preparative HPLC combined with L. casei bioassay demonstrated that most of the L. casei active folate appearing in plasma following a 20,000-micrograms dose of folic acid was due to the unmodified vitamin, only 5.6% being due to 5-CH3-H4 folic acid and with no detectable contribution from 5-CHO-H4 folic acid. The absorption characteristics of the system seem consistent between and within subject(s). No relationship could be demonstrated between predose levels of plasma 5-CH3-H4 folic acid and total folate in erythrocytes, which reflect the status of transport and storage forms of the vitamin, respectively.

Absorption↗
PubMed1989

Prevalence of neural tube defects in the Yorkshire Region.

The birth prevalence of neural tube defects (NTD) in the Yorkshire Region was determined for 1985 and 1986 by ascertainment of cases in live-and stillborn babies and of pregnancies terminated for NTD. Sixty-seven cases of anencephaly, 82 of spina bifida and 11 others were identified, a prevalence of 1.54 per 1000 total births. Eighty-eight per cent of pregnancies associated with anencephaly and 48 per cent of those with spina bifida were terminated.

Cross-Sectional Studies↗
PubMed1989

Onset and severity of hearing loss due to congenital rubella infection.

Of 111 children born in 1978-82 with congenital rubella infection, confirmed by the detection of rubella specific IgM shortly after birth, 68 were reported to be hearing impaired when notified to the National Congenital Rubella Surveillance Programme (NCRSP). The average age at which the diagnosis of hearing impairment was confirmed was 11.6 months. Recent audiograms showed a hearing loss that was usually uniform across all frequencies, equal in both ears and severe, averaging 93 dB across the range 250-4000 Hz. Despite the early diagnosis of congenital rubella and the known risk of deafness, only eight of 57 infants had been tested for auditory evoked responses in the first 6 months of life; all eight had severe hearing loss. Evidence of progressive hearing loss was found in only one of the 57 children. Definitive hearing tests (as distinct from screening tests) were frequently delayed until after the first birthday. Newborn babies identified as being at high risk of congenital deafness should have a full audiological assessment in early infancy.

Age Factors↗
PubMed1989

Neural tube defect recurrence after 'partial' vitamin supplementation.

A total of 227 mothers enrolled for periconceptional multivitamin supplementation because of previous neural tube defect (NTD) births took vitamins for less than the recommended minimum period (at least 28 days before conception until two menstrual periods have been missed). Of 213 examined infants/fetuses born to these partially supplemented mothers, two had NTD, one of whom followed four previous NTDs. The observed NTD recurrence rate is similar to that observed in fully supplemented mothers. A further 14 mothers started supplements before the second missed period but after the normal time of neural tube closure. Three of their offspring had NTD. The significance of this apparently high recurrence rate is discussed.

Ascorbic Acid↗
PubMed1987

Temporal relations between maternal rubella and congenital defects.

The Time relations between maternal rubella infection in pregnancy and the presence and type of defects in the children were determined from the records of 422 children with confirmed congenital rubella, registered in the National Congenital Rubella Surveillance Programme. In the 106 children born after laboratory-proven maternal infection, no defects were recorded following infection after the 17th week of pregnancy, but in the remaining 316 children defects followed infection reported to be as late as 33 weeks. The striking difference underlines the importance of serological investigation of pregnant women who present with a rash or a history of contact with rubella. With proven infection later than the 16th week the risk of fetal damage seems to be very small. Of 148 children followed up to school age, 40 (27%) attended normal schools.

Abnormalities, Multiple↗
PubMed1987

Congenital rubella in babies of south Asian women in England and Wales: an excess and its causes.

The incidence of congenital rubella was found to be 2.3 times higher in Asian than non-Asian births in England and Wales. This was attributed in part to higher susceptibility to rubella in Asian than non-Asian women, as shown by antenatal serological data from public health laboratories in Leeds, Luton, and Manchester. Examination of the ethnic origin of pregnant women requesting laboratory testing after contact with rubella or rash and of women with laboratory confirmed rubella in pregnancy also suggested that the disease was being underdiagnosed in pregnant Asian women. Failure to prevent congenital rubella by termination of infected pregnancies may therefore contribute to the increased incidence of the syndrome in Asians. Health education programmes about the dangers of rubella in pregnancy and of the need for vaccination can readily be promoted in the Asian community through existing ethnic organisations. Protection of other ethnic minorities likely to be at similar increased risk may require a vaccination programme aimed at national elimination of rubella.

Asia↗
PubMed1987

Weber-Christian panniculitis.

Two cases of Weber-Christian panniculitis with onset at 7 months and 3 years 6 months are described. Both show evidence of disturbances in immune mechanisms. The family of the first case has a high prevalence of coeliac disease, and the mother of the first patient also suffers from alopecia areata and dermatitis herpetiformis.

Child, Preschool↗