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Biomedical subjects

J Law

Publications and source records attributed to J Law.

At least 37 records · Page 2Linked to original sources
PubMed2001

Cancers detected and induced, and associated risk and benefit, in a breast screening programme.

Current cancer detection rates and dose levels in the UK Breast Screening Programme are used to compare numbers of cancers detected with numbers predicted to be induced by the screening process itself. Numbers of those detected are shown to exceed those induced by a large margin for women aged over 50 years. The associated benefit/risk ratio is also considered. For younger women this margin is progressively reduced but remains positive at least down to age 40 years, and possibly beyond. Women both with and without a family history of breast cancer are considered. Some implications for familial breast screening programmes are discussed. Some caution may be required before annual screening of women below the age of 35 years.

Adult↗
PubMed2001

Evaluating a programme to enhance vocabulary development in pre-schoolers.

This study was set up to investigate vocabulary development in a population of urban Indian socio-economically impoverished pre-schoolers. Since research has shown that a correlation exists with vocabulary and reading skills, hence better vocabulary would be indicative of fewer reading related problems. The introduction of an oracy programme in a nursery was evaluated and the results compared with those from a similar nursery not exposed to the programme. There was a significant difference in the growth of receptive vocabulary for the experimental group relative to the comparison group but no improvement in the expressive lexicon of either group. Results shed light on vocabulary development and its implications on later literacy progress, as well as changes to nursery practice in India.

Analysis of Variance↗
PubMed2001

Screening for speech and language impairment: a follow-up of true negatives and false positives.

It is important to ascertain the validity of screening and case-finding procedures in terms of long-term outcome, particularly if they constitute the primary mode of accessing services. This study is a follow-up of a group of True Negatives and False Positives from the 'original' study (Laing et al. 2000), which investigated the concurrent validity of a parent-led method and a formal screening method. Nine (29.03%) of the 31 children who were re-assessed fell below the cut-off point for referral and were identified as cases. In particular, as many as eight (57.14%) of the 14 false positives were referred.

False Positive Reactions↗
PubMed2000

The feasibility of universal screening for primary speech and language delay: findings from a systematic review of the literature.

This paper reports on a systematic review of the literature commissioned to examine the feasibility of universal screening for speech and language delay. The results, based on an examination of productivity figures, including positive predictive ability and likelihood ratio, indicate that a number of screening tests are adequate. Sensitivity was generally lower than specificity, and study quality was inversely related to both sensitivity and likelihood ratio, suggesting that it is easier to identify accurately children who do not have language and speech problems than those who do. The review concluded that there is insufficient evidence to warrant the introduction of universal screening at this stage. This paper discusses the type of data that would be needed to address this issue further and recommendations are made for alternative approaches to early identification.

Child, Preschool↗
PubMed2000

Factors affecting language development in West African children: a pilot study using a qualitative methodology.

Data on referral patterns to pre-school facilities for speech- and language-delayed children suggest that West African children are over represented relative to other ethnic/language groups. This study was set up as a pilot to explore some of the issues which distinguish this group of children and their families. A qualitative methodology was adopted to access the views of a small group of parents (nine) and professionals with direct experience of these services (three). Between them the parents had a total of 11 children who had received speech and language therapy services. Extensive in-depth interviews were transcribed and coded. The families are predominantly well educated with high expectations for their children. Their beliefs about child development in general and language development often differed from those of the professionals interviewed. For example, parents saw little direct link between very early language stimulation and subsequent school performance. West African parents also perceived that they had different (higher) expectations of behaviour than other families. It was generally accepted by all parties that the West African community experiences a high degree of stress resulting from a combination of interacting factors, namely pressures relating to employment, to immigration status, to matters financial and to expectations from family back in their own country. It is unclear exactly how these impact on the development of the child but there is an awareness that there may be a negative effect of such stress and that children's speech and language development may be one aspect of development that is affected. As a result of this pilot study a number of mechanisms relating to the relationship between environment factors and language development are proposed and suggestions are made regarding service provision for this community.

Africa↗
PubMed1999

Characterization and distribution of an oncofetal antigen (M2A antigen) expressed on testicular germ cell tumours.

M2A antigen is an oncofetal antigen associated with germ cell neoplasia, present in testis on fetal gonocytes and re-expressed on carcinoma in situ (CIS) and germ cell tumours. We developed a panel of monoclonal antibodies (mAb), M2A (IgG2a), D1-26 (IgG2b) and D2-40 (IgG1), to this antigen in order to characterize its structure and study its distribution among germ cell tumours. M2A antigen was purified by sequential lectin and antibody affinity chromatography and characterized as a monomeric M, 40 000 surface sialoglycoprotein, extensively glycosylated with O-linked carbohydrate structures, but devoid of N-linked sugars. Terminal sialic acid residues were required for reactivity with mAb M2A and D1-26, but not D2-40. Sections of 69 testicular germ cell tumours, fixed in formalin and embedded in paraffin, were stained with mAb D2-40 to examine the distribution of M2A antigen. Uniform membrane staining was observed in seminomas, and focal staining in 69% of embryonal carcinomas, 29% of teratomas and 25% of yolk sac tumours. CIS in the vicinity of all germ cell tumours also displayed uniform membrane staining. The characterization of M2A antigen, and the development of mAb which react with it in conventionally preserved archival specimens, provide important initiatives to study the origin and progression of germ cell neoplasia.

Animals↗
PubMed1998

Digital radiology using active matrix readout of amorphous selenium: detectors with high voltage protection.

A flat-panel x-ray imaging detector is being investigated for digital radiography and fluoroscopy. The detector uses a layer of amorphous selenium (a-Se) to convert x rays to a charge image, which is then electronically read out with a two-dimensional array of thin film transistors (TFTs). In order to sensitize the a-Se layer to x rays, a high voltage (of the order of several thousand volts) is applied to its top surface. The TFTs, which are at the bottom surface of the a-Se layer, are not subjected to any high voltage under normal radiological operational conditions since the pixel potential is < 10 V. However under a fault condition where these two events occur simultaneously: (1) suspended detector scan; and (2) an x-ray exposure more than ten times higher than normal, the voltage on the TFTs could rise to a damaging value. This paper describes a method for protecting the TFTs from high voltage damage under this fault condition. It employs a dual-gate TFT structure, one gate is for scanning control and the other is connected to the pixel electrode for high voltage protection. Before the pixel potential reaches a damaging value, the protection gate turns on the TFT automatically and drains excess charge away from the pixel thus providing a safe pixel saturation potential. In this paper, the characteristic curves of dual-gate TFTs are studied both theoretically and experimentally. The pixel x-ray response for imaging detectors with high voltage protection are predicted, and it is shown that with practical TFT designs the detector can provide a safe pixel saturation potential as well as satisfy the dynamic range required for diagnostic x-ray imaging applications.

Equipment Design↗
PubMed1998

Screening for primary speech and language delay: a systematic review of the literature.

Screening young children for developmental conditions such as speech and language delay is considered to be a part of the Child Health Surveillance programme in the UK. It is currently practised in many different ways throughout the country and like screening for other conditions conventionally identified in infancy, has been the subject of some concern for those responsible for providing such services. This systematic review (Law et al. 1998) was hypothesis driven and aimed to: i) establish whether, given the available evidence, there was sufficient evidence to warrant the introduction of universal screening for speech and language delays in children up to seven years of age; ii) identify gaps in the available literature; iii) identify priority areas in need of further investigation and iv); provide evidence-based recommendations for the future provision of services.

Child↗
PubMed1997

Evaluating intervention for language impaired children: a review of the literature.

Intervention studies are divided into those which have examined the effectiveness of specific techniques and those that have attempted to examine efficacy within the clinical context. Of the specific techniques, imitation and recasting or expansion have been the most commonly examined. Results suggest that they may be equally useful in reaching targets but that input in context has more chance of generalising. Combinations of techniques such as 'milieu teaching' seem especially promising. Evaluation of general language training strategies has tended to show good results relative to controls, although care has to be taken to discriminate between changes brought about to interaction skills and those to specific linguistic structures. The paper also covers issues associated with evaluation including clinical outcomes and methodological considerations. A number of research directions are suggested.

Child, Preschool↗
PubMed1997

Cancers detected and induced in mammographic screening: new screening schedules and younger women with family history.

The numbers of cancers detected and induced in breast screening programmes are examined for two-view screening, and for a 2 year screening interval, in contrast to the single view screening at a 3 year interval of the UK Breast Screening Programme up until early 1995. Two-view screening is also considered for the 1 year interval and age range of the current UK age trial (40-47 years). The corresponding figures for screening of groups having a family history of breast cancer are calculated and discussed. Breast cancer induction data are taken from National Radiological Protection Board publications. Cancer detection rates are based on observed rates where available, and calculated rates otherwise. The results of calculations indicate cause for concern if screening is to be extended below the age of 30 years (or below 35 years in certain categories), or below 40 years of age if family history groups are shown in the future to have a generally increased susceptibility to ionizing radiation. The importance of restricting dose to 2 mGy per film (mean glandular dose for a standard breast thickness of 4.5 cm) is stressed, together with the need ot maintain maximum image quality. This is especially true for the family history groups, who should only be screened in centres within established screening programmes, or in centres with equally strict quality control procedures.

Adult↗
PubMed1997

Reproducibility of Leeds TOR(MAM) mammographic test object plates.

Image quality test objects are essential tools for quality assurance in any branch of radiology. A major problem in test object construction is to make all examples of the test object closely comparable so that results from different examples can be compared. In mammography, the TOR(MAM) test object is considered to be the most sensitive of those generally available in the UK. This paper reports a comparison of 19 examples of this test object design, using five film scorers. Small differences in mean score were found to be statistically significant in about half of the test object plates tested. However, none of the plates differed from the overall mean at the 95% confidence level. Mean differences of score between single plates did not exceed 8%.

Humans↗