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Biomedical subjects

Y Edwards

Publications and source records attributed to Y Edwards.

At least 19 recordsLinked to original sources
PubMed2001

Canine TCOF1; cloning, chromosome assignment and genetic analysis in dogs with different head types.

We describe the construction of a dog embryonic head/neck cDNA library and the isolation of the dog homolog of the Treacher Collins Syndrome gene, TCOF1. The protein shows a similar three-domain structure to that described for human TCOF1, but the dog gene lacks exon 10 and contains two exons not present in the human sequence. In addition, exon 19 is differentially spliced in the dog. How these structural differences relate to TCOF1 phosphorylation is discussed. Isolation of a genomic clone allowed the exon/intron boundaries to be characterized and the dog TCOF1 gene to be mapped to CF Chr 4q31, a region syntenic to human Chr 5. Genetic analysis of DNA of dogs from 13 different breeds identified nine DNA sequence variants, three of which gave rise to amino acid substitutions. Grouping dogs according to head type showed that a C396T variant, leading to a Pro117Ser substitution, is associated with skull/face shape in our dog panel. The numbers are small, but the association between the T allele and brachycephaly, broad skull/short face, was highly significant (p = 0.000024). The short period of time during which the domestic dog breeds have been established suggests that this mutation has arisen only once in the history of dog domestication.

Amino Acid Sequence↗
PubMed2000

Mutation analysis and embryonic expression of the HLXB9 Currarino syndrome gene.

The HLXB9 homeobox gene was recently identified as a locus for autosomal dominant Currarino syndrome, also known as hereditary sacral agenesis (HSA). This gene specifies a 403-amino acid protein containing a homeodomain preceded by a very highly conserved 82-amino acid domain of unknown function; the remainder of the protein is not well conserved. Here we report an extensive mutation survey that has identified mutations in the HLXB9 gene in 20 of 21 patients tested with familial Currarino syndrome. Mutations were also detected in two of seven sporadic Currarino syndrome patients; the remainder could be explained by undetected mosaicism for an HLXB9 mutation or by genetic heterogeneity in the sporadic patients. Of the mutations identified in the 22 index patients, 19 were intragenic and included 11 mutations that could lead to the introduction of a premature termination codon. The other eight mutations were missense mutations that were significantly clustered in the homeodomain, resulting, in each patient, in nonconservative substitution of a highly conserved amino acid. All of the intragenic mutations were associated with comparable phenotypes. The only genotype-phenotype correlation appeared to be the occurrence of developmental delay in the case of three patients with microdeletions. HLXB9 expression was analyzed during early human development in a period spanning Carnegie stages 12-21. Signal was detected in the basal plate of the spinal cord and hindbrain and in the pharynx, esophagus, stomach, and pancreas. Significant spatial and temporal expression differences were evident when compared with expression of the mouse Hlxb9 gene, which may partly explain the significant human-mouse differences in mutant phenotype.

Abnormalities, Multiple↗
PubMed1999

Using standardized patients to assess presentation of a dental treatment plan.

In this new era of relationship-based care, involvement in treatment planning and goal setting is a high priority for patient satisfaction. This study reports on the use of standardized patients (SPs) in training third-year dental students to gather dental, medical, and psychosocial information from patients and to involve the patient in the decision-making process leading to the dental treatment plan. Among the skill areas measured, students were most successful in gathering dental information, with 94 percent of the students obtaining the complete set. Students were least successful in identifying the patient's goals for treatment (81 percent of the students identified the patients' goals). Students were most challenged by discussing sensitive topics with patients such as grief-related depression (25 percent of the students recognized and discussed such topics). It is important that dental schools familiarize students with patient issues and teach them how to talk effectively to patients about personal issues and to incorporate those issues into a discussion of the treatment plan for the patient. Standardized patients can be used effectively toward this end.

Adult↗
PubMed1998

Sequence comparisons and functional studies of the proximal promoter of the carbonic anhydrase 3 (CA3) gene.

Carbonic anhydrase 3 (CA3) is a member of a gene family encoding proteins which catalyse the hydration of CO2 to generate protons and bicarbonate ions for cellular ion transport and pH homeostasis. In mouse embryos CA3 is expressed at high levels in notochord and skeletal muscle and here we demonstrate that this pattern of expression is the same in the developing human embryo. To investigate mechanisms controlling CA3 transcription, we have isolated and compared 2.8kb of sequence flanking exon 1 from the mouse and human genes. Several segments of high sequence identity >80% have been identified, the longest segments of which represent a proximal promoter region and a putative enhancer element. We have shown previously that in cultured cells the human 2.8kb promoter region imposes high level myogenic specific transcription of a reporter gene. However, we now show that while this promoter region directed muscle-specific expression in transgenic mouse embryos this was subject to position effects.

Animals↗
PubMed1997

Prevalence of Q fever in a rural practice.

BACKGROUND: Q fever is a world-wide condition caused by the rickettsia Coxiella burnetii. It appears more prevalent in agrarian communities and may have serious sequelae. METHODS: A descriptive, cross-sectional, observational study using a randomly selected group of the adult working practice population in a rural practice in West Wales was devised. An immunofluorescence test, which identified past infection, was used to look for associations between C. burnetii seropositivity and farm-related or social activities, and to compare the findings with those of other studies. An attempt was made to establish a clinical profile for the illness Q fever. RESULTS: Twenty-one subjects were found to be seropositive to C. burnetii. No definite consistent clinical features were identified. Farming was undoubtedly a risk factor for the disease, maybe with other related factors also important. There was a possibility that alcohol had a protective effect. No sinister sequelae were described. CONCLUSIONS: Q fever occurs more frequently in farmers than in non-farmers, but was less common than previously thought. Is Q fever accurately described in medical textbooks? A case is made for a more co-operative approach between primary carers and epidemiologists in the study of illnesses in populations.

Agriculture↗
PubMed1995

A novel cDNA with homology to an RNA polymerase II elongation factor maps to human chromosome 5q31 (TCEB1L) and to mouse chromosome 11 (Tceb1l).

Few of the auxiliary factors that assist RNA polymerase II in the process of mRNA chain elongation have been identified. We have isolated a novel cDNA, Tceb1l, from mouse and human sources that encodes a 163-amino-acid protein and shows a significant level of identity with a recently identified RNA polymerase II transcription elongation factor, p15. Tceb1l is highly conserved throughout vertebrates and maps to mouse chromosome 11 and to the syntenic region of human chromosome 5q31. Tceb1l shows a restricted pattern of expression in the early mouse embryo, where it is absent from the neurectoderm; later Tceb1l is expressed in the caudal region of the neural tube, followed by widespread expression in many tissues, including the brain and spinal cord. These observations are consistent with Tceb1l being an RNA polymerase II elongation factor and suggest that Tceb1l/p15-like peptides may be a new family of proteins that influence RNA elongation.

Amino Acid Sequence↗
PubMed1995

The embryonic RNA helicase gene (ERH): a new member of the DEAD box family of RNA helicases.

DEAD box proteins share several highly conserved motifs including the characteristic Asp-Glu-Ala-Asp (D-E-A-D in the amino acid single-letter code) motif and have established or putative ATP-dependent RNA helicase activity. These proteins are implicated in a range of cellular processes that involve regulation of RNA function, including translation initiation, RNA splicing and ribosome assembly. Here we describe the isolation and characterization of an embryonic RNA helicase gene, ERH, which maps to mouse chromosome 1 and encodes a new member of the DEAD box family of proteins. The predicted ERH protein shows high sequence similarity to the testes-specific mouse PL10 and to the maternally acting Xenopus An3 helicase proteins. The ERH expression profile is similar, to that of An3, which localizes to the animal hemisphere of oocytes and is abundantly expressed in the embryo. ERH is expressed in oocytes and is a ubiquitous mRNA in the 9 days-post-conception embryo, and at later stages of development shows a more restricted pattern of expression in brain and kidney. The similarities in sequence and in expression profile suggest that ERH is the murine equivalent of the Xenopus An3 gene, and we propose that ERH plays a role in translational activation of mRNA in the oocyte and early embryo.

Amino Acid Sequence↗
PubMed1994

Evaluation of a transgenic mouse model for alpha-1-antitrypsin (AAT) related liver disease.

We have attempted to produce a transgenic mouse model of the neonatal liver disease associated with the human PIZ allele. Analysis of a number of transgenic mouse lines carrying either a normal human PIM gene construct or the mutant Z is reported. Using isoelectric focusing analysis of plasma from transgenic mice, we have shown that the human AAT proteins produced in mice are processed in a similar way to their counterparts in humans. By comparing the level of M and Z mRNA in liver with the levels of M and Z proteins in plasma we have inferred that, as in humans, the mutant protein tends to accumulate within the hepatocyte. Accumulation of Z protein has also been demonstrated by immunocytochemistry. Two of the M transgenic lines produce such high levels of the human protein that it, like the Z protein, accumulates as globules. Histological features of livers from 116 mice of different ages and genotypes were examined: 37 non-transgenic, 62 Z transgenic (23 low expressing and 39 high expressing) and 17 M transgenic mice, all high expressing. Cirrhosis or fibrosis was not seen in any animal and we were unable to find any evidence for neonatal liver disease. Some necrosis was seen in all genotypes and this increased significantly with age with one Z line showing significantly more frequent necrosis than any other group. This line, the highest expressing Z line, was back crossed onto 7 different genetic backgrounds but no major differences between the back crosses with respect to liver disease were observed. The mouse model we have developed is compared with other transgenic Z mouse models; none of these is representative of human neonatal liver disease. Our view is that the transgenic animals generated in these experiments may be most useful for investigating the liver manifestations that almost invariably occur in ZZ adults. Alteration of additional factors other than accumulation of Z protein, for example inactivation of the endogenous mouse genes or some environmental challenge, might produce a mouse model with more relevance to neonatal liver disease.

Animals↗
PubMed1993

Expression from the proximal promoter of the carbonic anhydrase 1 gene as a marker for differentiation in colon epithelia.

Carbonic anhydrase 1 (CA1) catalyses the reversible hydration of CO2 and is important for cellular diffusion of CO2, ion transport and pH regulation. The gene encoding CA1 (CA1) has two promoters. In adult colon epithelia the proximal promoter determines high levels of expression and the distal erythroid promoter is repressed. RNA in situ hybridisation shows that CA1 mRNA is abundant in differentiating cells of the colonic crypt as they migrate to the luminal surface, but is not present at the base of the crypts and levels are low on the luminal surface. It is likely that CA1 gene expression in these cells is regulated by differential transcription and/or mRNA stability. In contrast CA1 protein is localised predominantly on the luminal surface. Since CA1 mRNA and protein do not exactly co-localise it can be inferred that CA1 expression is also subject to post-transcriptional control. CA1 mRNA is significantly reduced in colon carcinoma and in adenomas from familial adenomatous polyposis patients. Loss of CA1 expression is associated with the disappearance of differentiated epithelial cells. Out of twelve colon carcinoma cell lines three, LIM1215, LIM1899 and HT115, expressed CA1 and nine did not. This variation in expression may also be associated with cell type differentiation.

Base Sequence↗
PubMed1992

Sequence of the complete cDNA and the 5' structure of the human sucrase-isomaltase gene. Possible homology with a yeast glucoamylase.

The complete sequence of the 6 kb cDNA and the 5' genomic structure are reported for the gene coding for the human intestinal brush border hydrolase sucrase-isomaltase. The human sucrase-isomaltase cDNA shows a high level of identity (83%) with that of the rabbit enzyme, indicating that the protein shares the same structural domains in both species. In addition to the previously reported homology with lysosomal alpha-glucosidase, the sucrase and isomaltase subunits also appear to be homologous to a yeast glucoamylase. A 14 kb human genomic clone has been isolated which includes the first three exons and the first two introns of the gene, as well as 9.5 kb 5' to the major start site of transcription. The first exon comprises 62 bp of untranslated sequence and the second starts exactly at the initiation ATG codon. Typical CAAT and TATA boxes are seen upstream of the first exon. A genetic polymorphism is described which involves a PstI site in the second intron. Southern blotting, sequencing and mRNA studies indicate that the structures of the sucrase-isomaltase gene and its mRNA are unaltered in the two human colon cancer cell lines Caco-2 and HT-29 in comparison with normal human small intestine.

Amino Acid Sequence↗
PubMed1992

Nucleotide sequence and chromosomal assignment of a cDNA encoding the large isoform of human glutamate decarboxylase.

Glutamic acid decarboxylase (GAD) catalyses the conversion of L-glutamic acid to the inhibitory neurotransmitter gamma-aminobutyric acid (GABA). Two forms of human GAD, GAD65 and GAD67, are encoded by two separate genes. A full length human GAD67 cDNA has been isolated from a human frontal cortex cDNA library and the nucleotide sequence determined. The GAD67 gene has been mapped to chromosome 2 using the polymerase chain reaction to amplify specifically the human sequence in rodent/human somatic cell hybrid DNA. This confirms that human GAD67 is not syntenic with the smaller GAD isoform GAD65 which has been assigned to chromosome 10. Production of polyclonal antiserum to a baculovirus-expressed GAD67 enabled immunocytological detection of GAD in the rat brain.

Amino Acid Sequence↗
PubMed1991

Usefulness of blood tests carried out during screening of the elderly population in one practice.

A screening programme for elderly patients in a six partner rural practice in west Wales had been found to be unhelpful. When screening became mandatory in April 1990 it was decided to make the programme more medical. The 773 patients aged 75 years or over in the practice were therefore offered a blood test as part of the mandatory screening programme. A total of 631 blood samples were taken. On checking haemoglobin concentrations, 39 patients (6.2%) were found to have levels below 11.5 g dl-1 (30 women, nine men). Forty two patients (7.1%) were found to have a blood urea concentration of more than 10.0 mmol l-1 and only three patients were found to be deficient in potassium, none of whom were receiving long term diuretic medication. Of the 16 patients (2.8%) discovered to have a lower than normal serum thyroxine concentration, 12 were not known to the practice. A raised mean corpuscular volume (greater than 100.0 fl) was found in 35 patients (5.9%) (24 women, 11 men), but only one of these was anaemic. However, among the patients with a low mean corpuscular volume (less than 80.0 fl), seven had a haemoglobin concentration of less than 11.5 g dl-1. Although this exercise has produced clinical benefit for a few patients, and has been interesting and academically stimulating, it cannot be concluded that the benefits obtained are worth the effort that has been involved.

Aged↗
PubMed1990

Mapping of mouse carbonic anhydrase-3, Car-3: another locus in the homologous region of mouse chromosome 3 and human chromosome 8.

At least six separate genes determining tissue- and organelle-specific isoforms of carbonic anhydrase are known. We have determined the chromosome location of one of these genes, carbonic anhydrase-3 (Car-3), in the mouse and carried out a linkage analysis of Car-1, Car-2, and Car-3. Car-3 has been assigned to band 3A2 by in situ hybridization. We identified a PstI restriction fragment length polymorphism between Mus spretus and Mus mus domesticus and, by using an interspecific backcross, showed that Car-3 is 2.4 +/- 1.7% SE from both Car-1 and Car-2, calculating genetic distance as percentage recombination. No recombinants were found between Car-1 and Car-2 in 100 backcross offspring, and when these data are combined with earlier results, these two loci are estimated to be 1.2 cM from each other at the 95% confidence interval. The three homologous carbonic anhydrase loci in man had earlier been assigned to 8q22, and the finding of linkage of Car-3 to Car-1 and Car-2 in the mouse adds another locus to the conserved segments on mouse chromosome 3 and human chromosome 8.

Animals↗
PubMed1990

The polymorphic human DNA sequence D8S8 assigned to 8q13-21.1, close to the carbonic anhydrase gene cluster, by isotopic and nonisotopic in situ hybridization and by linkage analysis.

Restriction fragment length polymorphism at the D8S8 locus is explained by the occurrence of at least two alternative alleles at two separate TaqI sites; TaqI-A allele frequencies 0.73 and 0.27 and TaqI-B allele frequencies 0.94 and 0.06. The D8S8 locus has been assigned to 8q13-21.1, near to the carbonic anhydrase (CA) gene cluster, by in situ hybridization to metaphase chromosomes using both tritium and immunofluorescently labelled probes. Linkage analysis using the CEPH family DNA panel indicates a close genetic linkage between D8S8 and CA3, with a lod score of +7.80 at theta = 0.05 in males.

Alleles↗
PubMed1989

Cloning and characterization of the major insulin-responsive glucose transporter expressed in human skeletal muscle and other insulin-responsive tissues.

Complementary DNA clones encoding a facilitative glucose transporter-like protein have been isolated from human small intestine and muscle cDNA libraries. This 509-amino acid protein has 65.3, 54.3, and 57.5% identity with the previously described human erythrocyte/HepG2, liver, and fetal muscle glucose transporter/transporter-like proteins, respectively. RNA blotting studies indicate that transcripts encoding this protein are very abundant in adult human skeletal muscle and subcutaneous fat. The adult skeletal muscle glucose transporter-like protein was expressed in vitro by cDNA-directed transcription and cell-free translation of the synthetic mRNA. The in vitro-synthesized protein reacted with a monoclonal antibody, 1F8, which recognizes the insulin-regulatable glucose transporter expressed in rat skeletal muscle, heart, and adipocytes. In contrast, in vitro-synthesized erythrocyte/HepG2 and fetal muscle glucose transporters did not react with 1F8. The high levels in adult skeletal muscle and subcutaneous fat of mRNA encoding the adult skeletal muscle glucose transporter and its specific reactivity with monoclonal antibody 1F8 suggest that this protein is the major insulin-regulatable glucose transporter expressed in skeletal muscle and other insulin-responsive tissues.

Adipose Tissue↗