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Biomedical subjects

A Fielder

Publications and source records attributed to A Fielder.

18 recordsLinked to original sources
PubMed1997

Visual search, perception, and visual-motor skill in "healthy" children born at 27-32 weeks' gestation.

Visual-perceptual, attentional, and visual-motor skills were examined in a group of 16 school-age children, born at 27-32 gestational weeks, who had performed normally on pediatric screening tests. Compared with 16 matched full-term controls, the preterms performed poorly on only two measures: they took longer to point to the missing arc of an annulus displayed on a computer screen and failed to find targets more often in a complex visual search task. They showed no deficits on tests of visual form extraction and closure. These data suggest that in the absence of any disability that is clinically detectable, prematurity results in a cluster of small but significant visual-motor impairments that persist into middle childhood. These relate to the maintenance of attention and visual-motor coordination, though visual form perception is not measurably affected. The results are discussed in the context of current neurobiological models of visual system organization.

Analysis of Variance↗
PubMed1996

Midwives' knowledge of haemoglobinopathies.

A good working knowledge of haemoglobinopathies is essential if midwives are to provide an equitable service. Almost half of the respondents had received no training in this area. Where training had been received, it was usually during basic midwifery education. Few had received haemoglobinopathies training since qualification as a midwife. Training was linked with higher knowledge levels, especially concerning patterns of inheritance of haemoglobinopathies. Further training sessions were linked with a further rise in knowledge levels. Respondents taught by haemoglobinopathies counsellors had higher knowledge levels than those taught by midwife teachers or doctors.

Anemia, Sickle Cell↗
PubMed1993

A mutation in the Norrie disease gene (NDP) associated with X-linked familial exudative vitreoretinopathy.

Familial exudative vitreoretinopathy (FEVR) is a hereditary disorder characterized by an abnormality of the peripheral retina. Both autosomal dominant (adFEVR) and X-linked (XLFEVR) forms have been described, but the biochemical defect(s) underlying the symptoms are unknown. Molecular analysis of the Norrie gene locus (NDP) in a four generation FEVR family (shown previously to exhibit linkage to the X-chromosome markers DXS228 and MAOA (Xp11.4-p11.3)) reveals a missense mutation in the highly conserved region of the NDP gene, which caused a neutral amino acid substitution (Leu124Phe), was detected in all of the affected males, but not in the unaffected family members, nor in normal controls. The observations suggest that phenotypes of both XLFEVR and Norrie disease can result from mutations in the same gene.

Adolescent↗
PubMed1993

Genetic mapping of a cone and rod dysfunction (Aland Island eye disease) to the proximal short arm of the human X chromosome.

A five generation family with an X linked ocular disorder has been investigated. The major clinical features were reduced visual acuity, nystagmus, and myopia. Although impaired night vision was not a symptom, using psychophysical and electrophysiological testing both rod and cone function were found to be abnormal in all affected males. No abnormality was detected in carrier females. Gene location studies showed X linked transmission of a gene that maps to proximal Xp11. The findings observed in this cohort are similar to those previously reported in both congenital stationary night blindness type 2 (CSNB2) and Aland Island eye disease (AIED). This study addresses whether CSNB2 and AIED are a single entity or whether the latter is a subset of the former.

Adult↗
PubMed1991

Tonic and phasic orientation in full-term and preterm infants.

Thirty-three full-term infants and thirty-eight preterm infants (on average born at 30 weeks gestation) were tested for their latency to turn toward checkered stimulus patterns (phasic orienting or "attention-getting") and for the duration of their initial fixation (tonic orienting or "attention-holding"). Plotted against the logarithm of the subjects' postconceptional age, turning latency fell linearly between 36 and 120 weeks, while fixation time fell abruptly at 53 weeks. Preterm and full-term infants showed the same developmental trends, implying that both of these attentional behaviors are biologically timetabled and that neither is greatly affected by premature extrauterine experience. Unexpectedly, phasic orientation in the first 30 postnatal days was significantly faster in preterm than in full-term infants, and fixation times failed to differ. Despite the necessary functional integration of phasic and tonic orienting in mature visual scanning and attention, the present results suggest an independence in their early postnatal development and that neither is mature at birth.

Arousal↗
PubMed1989

HLA-DR4 associated Dw types in rheumatoid arthritis.

Frequencies of HLA-DR4 and its related Dw types were compared between randomly selected normal controls and the index cases of multiplex rheumatoid arthritis (RA) families. A DR4 frequency of 68.3% was observed in index cases (n = 57) compared to 31.2% in normal controls (n = 96). Cellular typing with homozygous typing cells (HTCs) revealed significant increases of Dw4 (49.1% vs 22.9% RR = 3.2 p less than 0.001) and Dw14 (22.8% vs 2.1% RR = 13.9 p less than 0.001) in the index cases. A non-significant increase was seen for Dw13 (8.8% vs 4.1%). When DR4 positive patients and controls were compared, a significant increase was seen only for Dw14 (34.2% vs 6.6% RR = 7.3 p less than 0.01). Data from HLA genotyped RA and normal families allowed an examination of haplotype combinations of HLA-B antigens and DR4/Dw types to be made. HLA-Dw4 was predominantly found with B44 and Bw62 with nearly all DR4/Bw62 haplotypes being Dw4 positive. HLA-Dw13 was associated with B44 and Dw14 with Bw60, B44 and B27. Based on HTC and normal family data. Dw10 was found to be strongly associated with B38 containing haplotypes. Analysis of 69 C4A, C4B complement typed DR4 haplotypes failed to show any statistically significant association between Dw type and "complotype". However, there was a suggestion of C4A3. BQO being associated with Dw4 (34.2% vs 16.1% X2 = 2.9 p = ns) and C4A3, B1 with Dw14 (45.5% vs 27.6% X2 = 2.1 p = ns).(ABSTRACT TRUNCATED AT 250 WORDS)

Arthritis, Rheumatoid↗
PubMed1989

Intermodal enhancement of stimulus localisation in infants born prematurely.

The interaction of auditory and visual modalities in the enhancement of orientation was examined in premature and near-term infants by presenting them auditory or visual stimuli or auditory-visual stimulus combinations at various positions in sensory space. In 4.5--15-mo-olds, brisk orienting responses could be elicited to very peripheral stimulus positions but only when the stimulus consisted of a spatially coherent auditory-visual combination (i.e., where a sound and a light occurred at the same point in space). This occurred for all infants, irrespective of age or gestational age at birth. First, the result shows that infants can respond to visual stimuli at eccentric positions, beyond the supposed limits of their effective visual fields as measured by standard perimetry. Second, the result extends earlier studies showing that intersensory integration and stimulus localisation develop relatively normally in prematurely born infants. The auditory-visual enhancement test as used here may have a number of further uses and applications in the clinic and laboratory.

Arousal↗
PubMed1986

HLA frequency and haplotype analysis in a family study of adult onset rheumatoid arthritis.

Twenty-five families with probands who have rheumatoid arthritis (RA) were studied for clinical evidence of disease and for HLA status. This confirmed an association between RA and DR4 in 19/25 probands (76 per cent, p = 0.008). These 19 probands carried 24 haplotypes which contained DR4. There was no significant increase of DR4 haplotypes bearing B15(Bw62) or B44 when compared with published control haplotype data. The rare complement allele C4 B3 was detected as part of the extended haplotype A2 Cw3 B15(Bw62) DR4 C4 A*3B*3 in three probands with severe RA. Further studies to examine disease severity and autoantibody expression are in progress.

Arthritis, Rheumatoid↗
PubMed1982

HLA antigens and Bf allotypes in SLE: evidence for the association being with specific haplotypes.

The clinical features and HLA types of 67 unrelated patients with Systemic Lupus Erythematosus (SLE) were analyzed. The results showed: 1. An increase in frequencies of A1, B8, and DR3. These antigens are in close linkage disequilibrium and our data show that susceptibility to SLE is associated with the presence of all three antigens, implicating the specific haplotype which bears these antigens. 2. An increase in frequency of DR2, but not A3 or B7, these latter two antigens being in linkage disequilibrium with DR2. 3. 73.3% of the 54 Caucasoid SLE group were either B8 and/or DR2. This is in comparison with 37.5% in the controls and the difference is significant (p less than 0.001). 4. There was no association apparent between extent of disease, particular organ involvement and level of circulating antibodies to double stranded DNA with any HLA region product.

Adolescent↗
PubMed1977

Immunoglobulins and antinuclear antibodies in aqueous humour from patients with juvenile "rheumatoid" arthritis (Still's disease).

Aqueous humour and blood from twenty cataractous patients with chronic anterior uveitis and the monopauciarticular form of juvenile rheumatoid arthritis were tested for immunoglobulins G, A, and M and for autoantibodies, particularly those against nuclear antigens. The aqueous immunoglobulins were raised in the majority of patients even when the eyes were normal biomicroscopically. Raised IgG antinuclear antibodies were found in 85% of the aqueous samples. Information obtained from the study of aqueous humour from fourteen patients with senile cataract was used for statistical analysis of these data. The presence of high molecular weight immunoglobulins in the aqueous humour from patients with Still's disease suggests an abnormal blood-ocular barrier which may be responsible for the recurrence which follows an ostensibly treated primary attack of uveitis. The presence of antinuclear antibody in a few aqueous samples without a concomitant rise in the blood levels is suggestive of local antibody synthesis.

Antibodies, Antinuclear↗