An alternative to bougies for difficult intubation.
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Humans↗
Biomedical subjects
R Williamson
Publications and source records attributed to R Williamson.
DNA amplification for detection of the XV-2c polymorphism linked to cystic fibrosis.
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Chromosomes, Human, Pair 7↗
Polymerase chain reaction for detection of the pMP6d-9/MspI RFLP, a marker closely linked to the cystic fibrosis mutation.
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Chromosomes, Human, Pair 7↗
Genetic analysis of DNA from single human oocytes: a model for preimplantation diagnosis of cystic fibrosis.
Gene sequences in human oocytes were studied to investigate the possibility of diagnosing inherited or sporadic genetic disease before implantation after in vitro fertilisation. By specific amplification the possibility of analysing the DNA from single human oocytes for a specific gene was shown, and genotypes for markers closely linked to cystic fibrosis and Duchenne muscular dystrophy were determined. Single oocytes were used to approximate the total amount of DNA present in a single cell taken for biopsy from a 4-16 cell blastocyst. With a new technique for specific DNA amplification, the polymerase chain reaction, these data can be obtained within several hours of cell isolation. Extreme care must be taken to avoid any contamination of the sample with DNA from other sources. With this technique genotyping for single gene disorders is feasible with an accuracy and on a time scale that would allow implantation of the zygote after in vitro fertilisation without freezing.
Base Sequence↗
Substitution of serine for arginine in position 162 of TEM-type beta-lactamases extends the substrate profile of mutant enzymes, TEM-7 and TEM-101, to ceftazidime and aztreonam.
TEM-7 is a novel broad-spectrum beta-lactamase (Bla), selected in vivo, with a resistance profile similar to that of TEM-1 and TEM-2, but extended to ceftazidime (Caz) and aztreonam. Nucleotide sequencing revealed that the TEM-7 gene is almost identical with that of TEM-2. There was 1 bp change which would result in the substitution of Ser (TEM-7) for Arg (TEM-2) in amino acid (aa) position 162 (i.e., aa position 139 of the mature enzyme). This substitution, also found in TEM-101, a spontaneous in vitro derivative of TEM-1 selected on Caz, was assumed to be responsible for the extension of the substrate profile. The assumption was verified by exchange of a DNA fragment, carrying the mutation of the TEM-7-coding gene, with the homologous fragment of the TEM-1-coding gene in pBR322. In the three-dimensional model of class-A Bla [Joris et al., Biochem. J. 250 (1988) 313-324], aa 139 is located at the rim of the groove which contains the active center and adjacent to the evolutionarily conserved BoxV. It is speculated that extra free hydroxyl groups in this area may participate in the stabilization of otherwise non-substrate compounds.
Amino Acid Sequence↗
Electrical coupling between secondary hair cells in the statocyst of the squid Alloteuthis subulata.
The cephalopod angular acceleration receptor system has sensory response characteristics similar to those of the vertebrate semicircular canal system and, unusual for an invertebrate, contains secondary receptor hair cells. The experiments reported use intracellular recordings from pairs of hair cells to show that at least one subset of the hair cells is electrically coupled along the entire length of the crista section. The coupling can be reduced by application of heptanol or octanol. Intracellular injection of H+ ions into a hair cell reduces the coupling of cells on the opposite site of the injected hair cell but does not abolish it completely. It is proposed that the coupling is likely to result in an improvement in the signal-to-noise ratio of the receptor system, a reduction in overall frequency response, but an increase in the low frequency sensitivity.
Animals↗
Probe pJ1 [D7S402] detects a MspI RFLP on chromosome 7q31-32.
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Chromosome Mapping↗
Predisposing locus for Alzheimer's disease on chromosome 21.
Linkage between Alzheimer's disease and markers on the long arm of chromosome 21 was investigated in six families affected by disease of early onset. Linkage was confirmed and the disease locus shown to be centromeric to the locus D21S1/S11 on the long arm of the chromosome. It is argued that the data are consistent with the notion that all patients with Alzheimer's disease of genetic aetiology have a predisposing locus on chromosome 21.
Adult↗
Prenatal diagnosis of cystic fibrosis by using linked DNA markers in 138 pregnancies at 1-in-4 risk.
Prenatal diagnosis was carried out in 138 pregnancies at 1-in-4 risk for cystic fibrosis (CF) by using closely linked DNA markers, including XV-2c and KM-19. In fully informative families, 25 of 123 (20%) fetuses were predicted to be affected; 16 of these 25 pregnancies were terminated and 9 were continued. Postnatal sweat tests are completed in 42 cases; the diagnoses were confirmed in 4 of 4 infants predicted to be affected and in 37 of 38 infants predicted to be unaffected. One infant predicted to be a carrier had an abnormal sweat test after birth, but the mother also had an abnormal sweat test, and there was no evidence of an error in linkage analysis. The data indicate that prenatal diagnosis using linkage analysis is fully informative in most families and is highly reliable with either chorionic villus sampling or amniocentesis. Although outcome data are available on only 42 pregnancies, based on our experience, on general principles of linkage analysis, and on the tight linkage of the known DNA markers with CF, we recommend that DNA analysis replace microvillar intestinal enzyme analysis for 1-in-4 risk pregnancies when DNA is available from the propositus.
Cystic Fibrosis↗
Prenatal diagnosis of Friedreich ataxia.
Friedreich ataxia is a progressive neurodegenerative disorder affecting the peripheral and central nervous systems. One in 50,000 of the population are affected by this recessively inherited disorder, with onset usually before puberty. The recent localization of the disease locus to chromosome 9 has made it possible to provide genetic counselling to families with at least one affected child. Tight linkage of the disease mutation to an anonymous DNA marker MCT112 (D9S15) has been shown with a pairwise lod score of 36.1 at 0 = 0. We report here the first prenatal diagnosis in Friedreich ataxia. Using MCT112 and the confidence interval approach, we have calculated risks for a fully informative family with one affected sib.
Amniocentesis↗
Community attitudes to cystic fibrosis carrier testing in England: a pilot study.
Inexpensive and accurate carrier testing for cystic fibrosis (CF) will be possible in the near future. There are no existing studies on the attitudes of English persons in the community to carrier testing for CF or any other recessive disorder. We have conducted a trial study of 166 persons at two schools, two doctors' surgeries, and a family planning clinic. Only a minority had clear pre-existing knowledge of cystic fibrosis and its genetic nature. However, over 80 per cent of those questioned expressed interest in knowing their carrier status. Although it is well known that uptake can only be assessed when a service is in place, and while further studies are required to confirm that testing will be of interest to couples of reproductive age with no previous knowledge of CF, the data strongly suggest that there will be interest in community-wide testing for CF carrier status when such a test becomes available in the United Kingdom.
Attitude to Health↗
Confirmation and refinement of the localisation of the c-MEL locus on chromosome 19 by physical and genetic mapping.
The human gene locus c-MEL was identified following transfection of genomic DNA from the human melanoma cell line NK14; it has previously been assigned to chromosome 19 (p13.2-q13.2) by analysis of somatic cell hybrids. We have further refined the position of this gene to the proximal region of 19p (cen-p13.2), using cell hybrids containing only fragments of human chromosome 19. We have confirmed this physical localisation by linkage analysis with a recently described restriction fragment length polymorphism for the c-MEL gene, and mapped the locus within the region of the low density lipoprotein receptor gene (LDLR) (Lod 4.43, theta = 0.10) and the anonymous marker D19S11 (13.1.25) (Lod 9.33, theta = 0). This gene thus maps to a region of chromosome 19 involved in karyotypic abnormalities in a variety of malignancies including melanomas and leukaemias.
Cell Line↗
Detection of a rare allele with the pMP6d-9/MspI RFLP near the cystic fibrosis locus.
We report a rare allele detected using pMP6d-9, a probe very closely linked to cystic fibrosis (CF), on digestion with MspI. This allele has been found in normal and CF chromosomes, and therefore cannot be related to the mutation causing the disease.
Alleles↗
Molecular cloning and localization to chromosome 6 of mouse INT1L1 gene.
The human INT1L1 gene, which exhibits homology to the protooncogene INT1 is very closely linked to the MET gene and cystic fibrosis locus on human chromosome 7. In the present study we have isolated overlapping genomic clones that correspond to the mouse homolog of the INT1L1 gene and have used the cloned DNA as probes to examine the distribution of the mouse INT1L1 gene within a series of 35 mouse-hamster somatic cell hybrids. These analyses have localized the INT1L1 gene to mouse chromosome 6. In addition, we demonstrate that the mouse INT1L1 and MET genes are coamplified in lines of spontaneously transformed mouse NIH3T3 cells, indicating that these genes may remain closely linked within the mouse genome.
Amino Acid Sequence↗
Effect of diagnostic and therapeutic cordocentesis on maternal serum alpha-fetoprotein concentration.
We investigated the affect of cordocentesis (n = 36) and intravascular transfusion (n = 14) performed with a fixed needle guide on maternal serum alpha-fetoprotein levels. In 50% of the procedures, the placenta was anterior and punctured. For all patients, maternal serum alpha-fetoprotein levels rose 70.8% +/- 28%. The magnitude of the rise was unrelated to the number of attempts necessary, gestational age, or the initial maternal serum alpha-fetoprotein levels concentration. The location of the placenta was the sole identified variable related to the rise. A total of 44% of the patients had a significant increase in maternal serum alpha-fetoprotein level when the placenta was anterior. In contrast, only 4% of the patients had a significant rise in maternal serum alpha-fetoprotein level when the placenta was other than anterior. There was no difference in the frequency of a significant rise in maternal serum alpha-fetoprotein level concentration between the patients who underwent cordocentesis and those who underwent intravascular transfusion. On the basis of these findings, we recommend that when maternal isoimmunization is a potential concern and the placenta is anterior, the umbilical cord should be approached either through a window or laterally from the placenta.
Amniocentesis↗
Enterococcus raffinosus sp. nov., Enterococcus solitarius sp. nov. and Enterococcus pseudoavium sp. nov.
Deoxyribonucleic acid base composition, deoxyribonucleic acid-deoxyribonucleic acid hybridization, and biochemical studies were performed on some enterococci from clinical sources of uncertain taxonomic position. Our results indicate that 6 human strains, a single clinical isolate and a strain from bovine mastitis are genetically distinct from each other and all other previously described Enterococcus species and constitute three new species, for which the names Enterococcus raffinosus, Enterococcus solitarius and Enterococcus pseudoavium are proposed.
Base Composition↗
Amplification of DNA for detection of cystic fibrosis-linked polymorphisms.
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Cystic Fibrosis↗