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Biomedical subjects

L Butler

Publications and source records attributed to L Butler.

At least 19 recordsLinked to original sources
PubMed1992

NMDA-receptor mediated electrical epileptogenesis in the organotypic culture of rat hippocampus.

Extracellular field recordings were made in CA1 in the hippocampal explant cultures in oxygenated artificial cerebrospinal fluid. Schaffer collaterals were stimulated with 1-s trains of 60 Hz pulses every 10 min. Seizures were reliably elicited with progressive lengthening over 1-2 h. D-APV, an N-methyl-D-aspartate (NMDA) antagonist, stereoselectively blocked the development of seizures. Thus we have demonstrated that in vitro epileptogenesis occurs in hippocampal explant cultures through NMDA receptor mediated mechanisms.

2-Amino-5-phosphonovalerate↗
PubMed1992

Antenatal maternal serum screening for Down's syndrome: results of a demonstration project.

OBJECTIVES: To assess the implementation of antenatal screening for Down's syndrome in practice, using individual risk estimates based on maternal age and the three serum markers: alpha fetoprotein, unconjugated oestriol, and human chorionic gonadotrophin. DESIGN: Demonstration project of Down's syndrome screening; women with a risk estimate at term of 1 in 250 or greater were classified as "screen positive" and offered diagnostic amniocentesis. SETTING: Hospital and community antenatal clinics in four health districts in London. SUBJECTS: 12,603 women of all ages with singleton pregnancies seen between February 1989 and the end of May 1991, with follow up of the outcome of pregnancy completed to the end of 1991. MAIN OUTCOME MEASURES: Uptake of screening, detection rate for Down's syndrome, false positive rate, odds of being affected given a positive result, and uptake of amniocentesis in women with positive screening results, together with the costs of the screening programme. RESULTS: The uptake of screening was 74%. The detection rate was 48% (12/25), and the false positive rate was 4.1%, consistent with results expected from previous work based on observational studies. There was a loss of detection due to the selective use of ultrasound scans among women with positive screening results. One affected pregnancy occurred among 205 reclassified as negative; this illustrated the danger of false negatives occurring in this group and lends weight to the view that if an ultrasound estimate of gestational age is used it should be carried out routinely on all women rather than selectively among those with positive results. The estimated cost of avoiding the birth of a baby with Down's syndrome was about 38,000 pounds, substantially less than the lifetime costs of care. CONCLUSION: Antenatal maternal serum screening for Down's syndrome is effective in practice and can be readily integrated into routine antenatal care. It is cost effective and performs better than selection for amniocentesis on the basis of maternal age alone.

Amniocentesis↗
PubMed1991

Miller-Dieker syndrome with ring chromosome 17.

A girl presented at 6 weeks of age with failure to thrive and arching of the back. She had various dysmorphic features, hepatosplenomegaly, and developmental delay. The electroencephalogram and cranial ultrasound were abnormal, and a computed tomogram showed lissencephaly and apparent agenesis of the corpus callosum. Because of frequent aspiration she became oxygen dependent. She later developed intractable convulsions and died at the age of 9 months.

Abnormalities, Multiple↗
PubMed1991

Influence of environmental viral agents on frequency and tempo of diabetes mellitus in BB/Wor rats.

Elimination of environmental viruses by cesarean derivation of the University of Massachusetts colony of BB/Wor rats increased the frequency and accelerated the tempo of spontaneous diabetes among diabetes-prone (DP) rats. In contrast, the viral-antibody-free (VAF) environment did not alter the resistance of pre-VAF diabetes-resistant (DR) rats to spontaneous and RT6+ T-lymphocyte-depletion-induced diabetes. Pre-VAF and VAF rats have essentially the same lymphocyte subsets, and VAF-DP rats are susceptible to the adoptive transfer of diabetes and to the diabetes-accelerating effects of polyinosinic-polycytidylic acid injections. These results suggest that the presence of environmental viral pathogens may act to inhibit effector cell function in lymphopenic DP rats while enhancing effector cell activity in nonlymphopenic DR rats.

ADP Ribose Transferases↗
PubMed1990

De novo deletion of Xp22.2-pter in a female with linear skin lesions of the face and neck, microphthalmia, and anterior chamber eye anomalies.

A female infant is described with an unusual combination of eye and skin findings. Raw linear skin lesions on the face and neck were present at birth, healing to leave pigmented streaks. In addition she had left sided microphthalmia and bilateral sclerocornea. Chromosome analysis showed a terminal deletion of the short arm of the X chromosome (Xp22.2--pter). Clinical findings were similar to three previously described children with translocations involving Xp22.3. The condition probably represents a new syndrome distinct from incontinentia pigmenti and Goltz syndrome.

Chromosome Deletion↗
PubMed1989

Effect of kindling on potassium-induced electrographic seizures in vitro.

The properties of high [K+]o-induced spontaneous bursting and electrographic seizures in hippocampal slices prepared from rats subjected to kindling from either the lateral entorhinal cortex or the angular bundle were compared to those in control slices. Kindling enhanced the frequency of K+-induced burst-firing in the CA3 region and the duration of triggered bursts in the dentate gyrus, as previously reported. However, kindling had no influence on the characteristics or occurrence of electrographic seizures in the CA1 region of slices bathed in elevated [K+]o. In addition, the development of electrographic seizures in slices from control animals did not require a preconditioning period of burst input from the CA3 region.

Alkaloids↗
PubMed1989

Ocular and facial maldevelopment: the role of neural crest.

Three children are described who show a spectrum of clinical abnormalities affecting their eyes and non ocular tissues. These entities are best explained as disorders of neural crest migration and once recognised should lead to a search for other systemic developmental disorders. The mechanism of combined facial skeleton and eye malformation is discussed in the light of our current understanding of ocular embryology, and the justification for considering these and other entities as examples of Neurocristopathies is explored.

Abnormalities, Multiple↗
PubMed1989

Ultrasound fetal femur length measurement in the screening for Down's syndrome.

The fetal femur length determined by an ultrasound examination at between 13 and 39 weeks gestation in 83 pregnancies associated with Down's syndrome was statistically significantly less than the expected value for pregnancies with the same biparietal diameter examined in the same ultrasound department (P less than 0.0001). Expected values were based on linear regressions of femur length on biparietal diameter in 1340 control pregnancies from 27 ultrasound departments. The median value for the affected pregnancies was 0.94 times the expected value (95% CI 0.92 to 0.97). Eleven per cent of affected and 1.4% of control pregnancies had values less than or equal to 0.85 times the expected. The reduction in femur length in affected pregnancies was not related to biparietal diameter or to maternal age. Fetal femur length may be useful as an ancillary screening variable in the antenatal screening for Down's syndrome.

Down Syndrome↗
PubMed1989

Delayed microhyphaema with intraocular lenses: a retrospective study of eight patients.

Eight patients with delayed microhyphaema were identified from a computer data base of 1209 patients who had had cataract extraction with Binkhorst 4-loop intraocular lens insertion. Five cases were recurrent. The cases were examined to try and identify an underlying cause. No single cause was identified, but trauma, hypertension, and oral anticoagulants were found to be associated. Some episodes were asymptomatic. The wide variety of surgical technique and style of lens with which this complication has been reported implies multiple causative factors. The source of the bleeding and its management are discussed.

Adult↗
PubMed1989

The association of Angelman's syndrome with deletions within 15q11-13.

The inheritance of Angelman's syndrome, a disorder characterised by mental retardation, epilepsy, ataxia, and a happy disposition, is debated because affected sibs occur less frequently than expected with autosomal recessive inheritance. After discovering two unrelated patients with a small deletion of the proximal long arm of chromosome 15, 10 further patients with Angelman's syndrome were reassessed. Five had apparently normal karyotypes, four had a deletion within 15q11-13, and one had a pericentric inversion, inv(15)(p11q13) involving the same chromosomal region. In the latter case, the healthy mother had the same pericentric inversion, indicating that the patient also had a submicroscopic mutation on his other chromosome 15. These data map the Angelman locus to 15q11-13 and suggest that de novo visible deletions (associated with a low recurrence risk) and autosomal recessively inherited cases combine to give an overall sib recurrence risk of less than 25%.

Ataxia↗
PubMed1989

Genetic studies in inbred BB/Wor rats. Analysis of progeny produced by crossing lymphopenic diabetes-prone rats with nonlymphopenic diabetic rats.

BB/Wor diabetes-prone (DP) rats are lymphopenic and frequently develop insulin-dependent diabetes. Diabetes-resistant (DR) BB/Wor rats are not lymphopenic and become diabetic rarely and at a significantly younger age. To examine the genetic basis for diabetes, lymphopenia, and age at onset of diabetes among inbred BB/Wor rats, we crossed nonlymphopenic diabetic rats with lymphopenic DP animals and studied F1, F2, and backcross progeny. F1 rats were neither diabetic nor lymphopenic. Diabetes (both types) and lymphopenia reappeared among F2 rats, confirming the permissive association of diabetes and lymphopenia and the recessive nature of both. The absence of diabetes in F1 rats also suggested that the combination of genes responsible for diabetes among lymphopenic and nonlymphopenic rats may be distinct. Nonlymphopenic parental, F1, and F2 rats revealed normal lymphocyte subsets, including CD8+ and RT6+ T-lymphocytes. Lymphopenic parental and F2 rats revealed the absence of CD8+ and RT6+ cells, indicating that these T-lymphocyte abnormalities of lymphopenic DP rats segregate with the lymphopenia gene. The distribution of the ages at onset of diabetes among F2 lymphopenic and F2 intercross rats was significantly earlier than among lymphopenic parental and backcross animals, suggesting that the age of diabetes onset is a heritable trait and that the gene(s) or genetic modifier(s) responsible for the earlier onset of F2 diabetes was acquired from the nonlymphopenic parents. Our genetic studies also confirmed the observations that the 2- and 7-kilobase Bam HI fragments of the MHC class I region do not correlate with diabetes or lymphopenia.

Age Factors↗
PubMed1988

The feeding habits of the tsetse, Glossina pallidipes Austen on the south Kenya coast, in the context of its host range and trypanosome infection rates in other parts of east Africa.

The results of blood-meal identifications for 651 Glossina pallidipes from 5 subpopulations near the Kenya coast south of Mombasa, and one, 70 km inland, are presented. Bushpigs and/or warthogs were important hosts for G. pallidipes at all sites. Other major hosts included elephant, buffalo and bushbuck where they were present, and on a dairy ranch nearly 30% of feeds were taken from cattle. There was a general relationship between the numbers and diversity of wild herbivores and the abundance of G. pallidipes. These results are discussed in relation to published data on feeding patterns and trypanosome infection rates for G. pallidipes from other parts of East Africa. Overall, there are significant correlations between the proportions of bovid feeds and T. vivax infections. Bovid-feeding G. pallidipes populations with high T. vivax infection rates in south-east Uganda and western Kenya contrast with the coastal, suid-feeding populations with low T. vivax rates. These characteristics are presented as clines extending across East Africa.

Africa, Eastern↗