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Biomedical subjects

G Barrett

Publications and source records attributed to G Barrett.

At least 37 records · Page 2Linked to original sources
PubMed1998

Are women who have abortions different from those who do not? A secondary analysis of the 1990 national survey of sexual attitudes and lifestyles.

Studies of women undergoing termination of a pregnancy are often used to make recommendations about family planning and health education policy. However, it is not clear how similar the women in these studies are to the general population of women of childbearing age. Our secondary analysis of the National Sexual Attitudes and Lifestyles Survey allowed us to test the hypothesis that women who have undergone an abortion are the same as those who have not (in terms of socio-demographic characteristics, lifestyles, and attitudes). Our findings show significant differences between these two groups of women, particularly regarding ethnicity, marital status, number of natural children, lifetime number of sexual partners, and attitudes to abortion. We conclude that family planning/reproductive health services and health education policies need to take these differences into account and that further research is required to explain why these differences arise.

Abortion, Legal↗
PubMed1997

Key problems in using health status measures.

This article describes the development of health status measures and the benefits to be gained from their use. The difficulties in conceptualising and quantifying health are described. The authors conclude that a critical approach to the use of health status measures is needed if these instruments are to be of benefit to health care and health research.

Attitude to Health↗
PubMed1997

Event-related potentials associated with judgment: comparison of S1- and S2-choice conditions in a contingent negative variation (CNV) paradigm.

To elucidate the functional role of association cortex in judgment and decision-making about external stimuli, the scalp topography of contingent negative variation (CNV) recorded in 9 normal volunteers was compared in two settings; dichotomous S1- and S2-choice paradigms using right wrist extension or flexion movement upon S2 as the choice reaction task with an S1-S2 interstimulus interval of 2 s. Two main findings were obtained. First, early CNV in the S1-choice paradigm consisted of a frontal to frontopolar midline negative potential, most likely representing judgment more than orienting response, and a left-sided parietal positive potential, at least partially representing P3b, whereas in the S2-choice paradigm it consisted only of a smaller frontal negative potential shift, most likely representing merely an orienting response. This suggests that the prefrontal and left parietal association cortexes might be active in the judgment and decision-making process. Second, after S2, two positive peaks (334 and 545 ms after S2) were observed at the midline central to left parietal areas only in the S2-choice paradigm. In the S1-choice paradigm, one large negative peak (275 ms after S2) was observed. We postulate that the first peak of the S2-choice paradigm is related to decision making or judgment and that the second peak is related to the following cognitive process. We conclude that at least the prefrontal and parietal association cortexes generate transient potentials accompanying judgment, and possibly decision making.

Adult↗
PubMed1997

Use of contraception in women who present for termination of pregnancy in inner London.

OBJECTIVES: To describe the contraceptive usage of women undergoing termination of pregnancy in order to identify problems with contraception, and therefore suggest ways in which contraceptive services can be improved. DESIGN: Prospective study of attenders for NHS termination of pregnancy over a three month period. SETTING: Community based assessment clinics for NHS termination of pregnancy in inner London. SUBJECTS: Two hundred and sixty-nine women asking for assessment for NHS termination of pregnancy. MAIN OUTCOME MEASURES: Source of contraception, method used around time of conception, and problems experienced. RESULTS: Respondents tell into three groups: those using contraception around the time they became pregnant; those who had ceased to use contraception; and those that had never used contraception. The method of contraception used by the majority of the first group was the condom and the main source of the method was the chemist shop. The second group had most commonly used oral contraceptives in the past and had ceased use in many cases as a result of side effects. The majority of the third group did not speak English and had limited knowledge of methods of contraception. CONCLUSIONS: High usage of chemists means women avoid service providers who could offer help and advice. Women were prepared to put themselves at risk of unwanted pregnancy rather than return for further help and the lack of knowledge about emergency birth control was of some concern. The needs of black and ethnic minority women requires detailed work to improve access and acceptability of contraceptive services.

Adolescent↗
PubMed1996

Event-related potentials during paired associate memory paradigm.

We have studied event-related potentials (ERPs) during a visual paired association task with delayed discrimination in 10 normal right-handed subjects. After subjects completely memorized 4 pairs of figures during a learning period, they were presented with each cue (S1) and asked to judge whether the following figure (S2) formed one of the memorized pairs or not. A choice reaction task with delay was used for control in an attempt to identify brain activity specifically related to memory function. ERPs were recorded from 21 scalp electrodes and those occurring between the S1 and S2 presentation were analyzed. Two ERP components associated with memory function were identified in the difference waveform between the responses in the paired association task and those in the choice reaction task. One was a posterior positive component which appeared between 390 ms and 1100 ms after the S1 presentation and the other was a sustained frontal negative component which began at about 1100 ms after S1 and ended just before the S2 presentation. Both potentials were distributed predominantly on the scalp overlying the left hemisphere. It is postulated that the early posterior positive component may reflect retrieval of information from association memory, whereas the late frontal negativity may reflect retention of information in working memory.

Adult↗
PubMed1995

Pain-related somatosensory evoked potentials following CO2 laser stimulation of foot in man.

Since our previous study of pain somatosensory evoked potentials (SEPs) following CO2 laser stimulation of the hand dorsum could not clarify whether the early cortical component N1 was generated from the primary somatosensory cortex (SI) or the secondary somatosensory cortex (SII) or both, the scalp topography of SEPs following CO2 laser stimulation of the foot dorsum was studied in 10 normal subjects and was compared with that of the hand pain SEPs and the conventional SEPs following electrical stimulation of the posterior tibial nerve recorded in 8 and 6 of the 10 subjects, respectively. Three components (N1, N2 and P2) were recorded for both foot and hand pain SEPs. N1 of the foot pain SEPs was maximal at the midline electrodes (Cz or CPz) in all data where that potential was recognized, but the potential field distribution was variable among subjects and even between two sides within the same subject. N1 of the hand pain SEPs was maximal at the contralateral central or midtemporal electrode. The scalp distribution of N2 and P2, however, was not different between the foot and hand pain SEPs. The mean peak latency of N1 following stimulation of foot and hand was found to be 191 msec and 150 msec, respectively, but there was no significant difference in the interpeak latency of N1-N2 between foot and hand stimulation. It is therefore concluded that N1 of the foot pain SEPs is generated mainly from the foot area of SI. The variable scalp distribution of the N1 component of the foot pain SEPs is likely due to an anatomical variability among subjects and even between sides.

Adult↗
PubMed1995

Evoked potentials in a subject with a large-fibre sensory neuropathy below the neck.

The results from experiments in various modalities of evoked potentials are described in a subject with a complete large peripheral neuropathy below the neck. He has no tactile or position sensitivity below that level, but has retained fatigue, pain, and temperature sensation. Percutaneous electrical stimulation of peripheral nerves led to scalp recorded evoked potentials with thresholds and propagation velocities compatible with conduction along A-delta peripheral pathways. CO2 laser evoked potentials were similar to those seen in controls, further support for intact A-delta peripheral fibres. Movement-related cortical potentials (MRCPs) were recorded associated with active and passive movement of the middle finger. The former were normal, evidence that the termination of the MRCP is not dependent on peripheral feedback. By comparing passive MRCPs between controls and the subject it was possible to establish which parts of the potentials are visual and which are proprioceptive and to gain evidence of central reorganisation in the subject. Magnetic brain stimulation was used to show that the subject did not perceive induced movement, had a normal centrally originating silent period, and could focus his attention during real and imagined movement of the finger more successfully than could normal controls.

Attention↗
PubMed1995

Services for children with HIV/AIDS: the views of parents.

In this qualitative study, the parents of ten children who attended an inner-London teaching hospital for HIV/AIDS were interviewed to find out their views on the services. Speaking from their own experiences, parents expressed a high level of satisfaction with the specialist paediatric care at the teaching hospital but had little confidence in the expertise of other hospitals or of GPs and health visitors. Few cases had been identified antenatally; the diagnosis of HIV/AIDS was often made only after the child had become ill and been investigated for a variety of diseases before being tested for HIV. The families felt considerable anxiety about the future, especially about what would happen if both child and parent were to become ill at the same time. The increasing number of HIV-infected mothers and children means that in future the caseload and expertise of the specialist centres will need to be shared with the primary health care team.

Attitude to Health↗
PubMed1994

'We just want to be a normal family...'. Paediatric HIV/AIDS services at an inner-London teaching hospital.

The nature of the HIV epidemic in the UK is changing with the increasing number of infected women and children. This recent onset means that there are few data about the specific problems of HIV in families. This study examines current issues in service provision to HIV infected children and their families at an inner-London teaching hospital. A sample of ten families were interviewed, from a caseload of approximately 100 HIV-positive children. Of the ten children, seven were under the age of 5 years. All the children were vertical transmissions and six of the mothers were from Sub-Saharan Africa. Only three of the ten children were identified antenatally. In terms of service provision, families were very satisfied with the care provided by the study hospital's paediatric HIV team but felt that the hospital's paediatric and adult HIV services were poorly co-ordinated and impractically located over different sites. Families did not have confidence in GP and community services, preferring to use hospital services which they felt to have more expertise in paediatric HIV. Future policy developments will have to confront the hospital-centred nature of paediatric HIV services and develop primary and community care services.

Acquired Immunodeficiency Syndrome↗