Radionuclides and the investigation of peripheral vascular disease.
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Humans↗
Biomedical subjects
A Edwards
Publications and source records attributed to A Edwards.
Genetic marker technology.
Advances in our understanding of polymorphisms found in eukaryotic genomes and improved methods for studying genetic markers should facilitate genetic linkage mapping and other applications. Progress within the past year includes characterization of the types, frequencies, and properties of tandemly repeated sequences, methods for obtaining the DNA sequence flanking genetic markers for use in the polymerase chain reaction, and new detection systems featuring automation and multiplexing.
Animals↗
Expression and function of Qa-2 major histocompatibility complex class I molecules in transgenic mice.
Qa-2 molecules are weak transplantation antigens encoded by class I genes of the major histocompatibility complex. When expressed in transgenic CBA mice, Qa-2 molecules provoke rapid rejection of skin grafts and strong, Qa-2 specific, cytotoxic T-cell responses. Efficient rejection of skin grafts from Qa-2 transgenic mice takes place when Qa-2 molecules are attached to the cell membrane with a glycophosphatidyl anchor or by a transmembrane protein domain, except that rejection times are slightly longer in the former case. These results demonstrate that Qa-2 molecules can behave as major transplantation antigens, as do closely related H-2 molecules. Failure of Qa-2 molecules to provoke strong T-cell responses in non-transgenic mice is probably due to the very low level of expression of Qa-2 molecules in skin keratinocytes from such mice since these cells express increased levels of Qa-2 molecules in all Qa-2 transgenic mice.
Animals↗
Linkage of the gene for an X-linked mental retardation disorder to a hypervariable (AGAT)n repeat motif within the human hypoxanthine phosphoribosyltransferase (HPRT) locus (Xq26).
We recently reported a new X-linked mental retardation (XLMR) disorder in a four-generation family of Dutch descent. Features included Dandy-Walker malformation, basal ganglia disease, and seizures. Twenty-six family members, including two living affected males and two obligate carriers, were available for study. No evidence of linkage was observed between the disease locus and RFLPs from several X-chromosome regions, including Xp21-p22 (13 markers), proximal Xq (four markers), and Xq28 (three markers). However, a new hypervariable short tandem repeat (STR) within the HPRT gene at Xq26 showed positive linkage to the disease locus, with a maximum lod score of 2.19 at a recombination fraction of 0. A second hypervariable marker in Xq26, the dinucleotide repeat XL90A3 (DXS425), showed a lod score of .84 at a recombination fraction of .11. Both the HPRT and DXS425 markers were typed in 40 CEPH families, and subsequent multipoint linkage analysis showed the following order: Xcen-DXS425-(HPRT,XLMR)-F9-qter. HPRT and these flanking markers are therefore useful for carrier detection and prenatal diagnosis in this family. This study illustrates that hypervariable STRs will be powerful tools for linkage analysis and genetic diagnosis, particularly when relatively small families are involved.
Adenine Nucleotides↗
DNA typing and genetic mapping with trimeric and tetrameric tandem repeats.
Tandemly reiterated sequences represent a rich source of highly polymorphic markers for genetic linkage, mapping, and personal identification. Human trimeric and tetrameric short tandem repeats (STRs) were studied for informativeness, frequency, distribution, and suitability for DNA typing and genetic mapping. The STRs were highly polymorphic and inherited stably. A STR-based multiplex PCR for personal identification is described. It features fluorescent detection of amplified products on sequencing gels, specific allele identification, simultaneous detection of independent loci, and internal size standards. Variation in allele frequencies were explored for four U.S. populations. The three STR loci (chromosomes 4, 11, and X) used in the fluorescent multiplex PCR have a combined average individualization potential of 1/500 individuals. STR loci appear common, being found every 300-500 kb on the X chromosome. The combined frequency of polymorphic trimeric and tetrameric STRs could be as high as 1 locus/20 kb. The markers should be useful for genetic mapping, as they are sequence based, and can be multiplexed with the PCR. A method enabling rapid localization of STRs and determination of their flanking DNA sequences was developed, thus simplifying the identification of polymorphic STR loci. The ease by which STRs may be identified, as well as their genetic and physical mapping utility, give them the properties of useful sequence tagged sites (STSs) for the human genome initiative.
Asian People↗
Prevention of insulin-dependent diabetes mellitus in non-obese diabetic mice by transgenes encoding modified I-A beta-chain or normal I-E alpha-chain.
Insulin-dependent diabetes mellitus (IDDM) is a disease with an autoimmune aetiology. The inbred non-obese diabetic (NOD) mouse strain provides a good animal model of the human disease and genetic analysis suggests that, as in man, at least one of the several genes controlling the development of IDDM is linked to the major histocompatibility complex. The NOD mouse does not express I-E owing to a deletion in the promoter region of the I-E alpha-chain gene, and the sequence of NOD I-A beta-chain in the first external domain is unique with His 56 and Ser 57 replacing Pro and Asp, respectively, at these positions. There has been considerable interest in the role amino acid 57 might have in conferring susceptibility to autoimmune diseases, including IDDM. The presence of a charged residue (such as Asp) at this position might affect the conformation of the peptide binding groove. But it could be assumed that Pro 56 gives rise to a different conformation of I-A beta-chain than does His 56. We therefore constructed transgenic NOD mice in which the transgene encoded a modified A beta nod with Pro 56, and studied its effect on the development of IDDM in this mouse strain. Previous studies have suggested that NOD mice expressing I-E as a result of the introduction of an I-E alpha-chain (E alpha) transgene are protected from the development of insulitis and hence IDDM. To explore further the protective effect of this molecule we constructed a second class of transgenic NOD mouse carrying an E alpha d transgene. Both transgenes protected the mice from IDDM, but this was not associated with a complete deletion of any T cells expressing commonly used T-cell receptor V beta genes.
Animals↗
Clinical and laboratory findings in the Paul-Bunnell negative glandular fever-fatigue syndrome.
Forty-one patients with recurrent fatigue were studied for evidence of symptom clustering, abnormal laboratory findings and infection with novel viruses. Symptom enquiry and investigations were repeated 4 months later. Four patients were found to have diseases compatible with their symptoms. In those remaining, an initial acute onset of symptoms was associated with an intermittent course, tender glands and a raised number of T suppressor lymphocytes. Raised numbers of T suppressor lymphocytes at follow-up correlated with resolution of symptoms. Antibodies to human herpesvirus 6 (HHV-6) were found in 75% of the patients as compared to 53% of a control group and more patients than controls were strongly seropositive. Some patients with chronic fatigue have a pattern of illness which suggests glandular fever, although acute infection with Epstein-Barr virus (EBV) is not demonstrated. Primary or reactivation infection with HHV-6 may have a role in this syndrome.
Adolescent↗
Automated DNA sequencing of the human HPRT locus.
The complete sequence of 57 kb of the human HPRT locus has been determined using automated fluorescent DNA sequencing. The strategy employed increasingly directed sequencing methods: A randomly generated M13 library was sequenced to generate contiguous overlapping sets of sequences (contigs). M13 clones at the ends of these contigs were further sequenced using M13 (universal and reverse) and custom oligonucleotide primers to order the contigs and to complete the sequencing project. The human HPRT sequence includes 1676 bp 5' and 15,238 bp 3' to exons 1 and 9, respectively. The sequence contains 49 representatives of the Alu repeat, along with several other types of repetitive sequences. The Alu sequences exhibit a biased orientation, with those sequences in the first half of the locus oriented in the minus direction relative to transcription of the gene (3'----5' = 77%, P less than 0.005) and those sequences in the latter half of the locus oriented randomly (5'----3' = 67%, P less than 0.5). The development and performance of the sequencing strategy and the features of the human HPRT gene are presented.
Amino Acid Sequence↗
Multiplex DNA deletion detection and exon sequencing of the hypoxanthine phosphoribosyltransferase gene in Lesch-Nyhan families.
The Lesch-Nyhan (LN) syndrome is a genetically lethal human neurological disease that results from mutations that inactivate the hypoxanthine phosphoribosyltransferase (HPRT) gene. The elucidation of the complete DNA sequence of the human HPRT gene locus has enabled the construction of multiple oligonucleotide primer sets for the simultaneous in vitro amplification of all nine HPRT exons. The multiplex polymerase chain reaction provides a facile assay for the detection of HPRT exon deletions and the reaction products can be analyzed by direct automated fluorescent DNA sequencing to identify subtle alterations in the gene. Alterations have been identified in the HPRT genes from 15 independent LN cases, and 10 LN family studies were performed. The sequencing method uses solid supports and is sufficiently simple and sensitive to be a favored approach for LN diagnosis. LN heterozygotes can be diagnosed without reference to the affected male. In addition, these procedures will be useful for somatic mutagenesis studies.
Base Sequence↗
Sexually transmitted diseases in lesbians.
The limited published data support the assumption that lesbians are a low risk group for sexually transmitted diseases (STDs). However, there are virtually no contemporary data and the older papers do not take into account genital wart virus infection, now the third most prevalent STD in Britain. One of the dangers in assuming that lesbians are a 'safe group' for STD and allied disorders is that patients may not attend for regular cervical cytology and could be at risk of developing cervical cancer. In an unselected series of 27 lesbians attending a genitourinary medicine clinic, the most important findings were a relatively high prevalence of the viral STDs, herpes simplex and human papillomavirus. Additionally, 10 patients had abnormal cytology ranging from inflammation to dyskaryosis. There is a need for more information about the true prevalence of STDs in this group and evaluation of the risk factors for female-to-female transmission of infections. Lesbians should continue to have regular cervical smears, especially as many have had earlier heterosexual intercourse.
Adult↗
Attempt to show inhibition by oxygen in the modifying factor assay.
An Australian laboratory has demonstrated that antibodies to certain strains of enteric bacteria react with cells from HLA-B27-positive patients with a 'modifying factor' (MF) from these bacteria. These observations have proved difficult to reproduce. We investigated the possibility that oxygen inhibits the test by blocking B27, but we were unable to obtain consistent positive results.
Antibodies, Bacterial↗
Free and serum testosterone levels in 276 males: a comparative study of rheumatoid arthritis, ankylosing spondylitis and healthy controls.
A cross-sectional study of testosterone levels in 276 males was undertaken. Of these 87 were RA patients, 48 males with AS and 141 were healthy controls. Free and serum testosterone levels were significantly lower in the RA males than in either the AS group or the healthy controls (p less than 0.001). This difference was unaffected by age. No differences were seen in testosterone levels between DR1 or DR4 RA patients compared to those without these antigens. No evidence of hyperandrogenicity was seen in the AS group. The finding that males with RA have lower androgen levels than both normal controls and a disease group with inflammatory spondarthritis supports the hypothesis that male sex hormones may be a protective factor against the development of RA.
Adult↗
The place of lung 99mTc DTPA aerosol transfer in the investigation of lung infections in HIV positive patients.
Pneumocystis carinii pneumonia (PCP) is the most common cause of pneumonia in HIV antibody positive patients, but other pneumonias remain important, i.e. streptococcal and mycobacterial infections. A definitive diagnosis relies on obtaining samples from the lung either noninvasively (induced sputum), or invasively (bronchoalveolar lavage, transbronchial or open lung biopsy). We have used the noninvasive technique of nebulized 99mTc DTPA transfer, to assess patients with PCP (n = 30) and other lung infections (n = 20) to see whether this test will distinguish between the various infections. The presence of a biphasic, rapid transfer curve indicates severe extensive alveolar damage and is seen in PCP or legionella pneumonia. The mean transfer time (T50 +/- SEM) for patients with PCP (whether smokers or nonsmokers) was 2.1 +/- 0.2 min, and for two of the patients with legionella 3.2 min. In PCP effective treatment causes the transfer to slow (mean T50 22.7 +/- 3.3 min, n = 24) and become monoexponential. Other causes of these changes in transfer are discussed. The other pneumonias (streptococcal, mycobacterial, and staphylococcal) did not result in biphasic curves or very rapid times, their T50 values are indistinguishable from cigarette smokers. In this patient group the DTPA transfer is a useful noninvasive investigation with a very rapid, biphasic curve indicating a high probability of PCP.
Adult↗
Pseudomonas immune globulin therapy improves survival in experimental Pseudomonas aeruginosa bacteremic pneumonia.
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Animals↗
Characterization of muscarinic receptors: type M2 (subtype B) on neuro-2A neuroblastoma cells.
The binding of the nonselective muscarinic antagonist, [3H]N-methylscopolamine (NMS) to a mouse neuroblastoma cell line (Neuro-2A) and its coupling to the inhibition of adenylate cyclase were characterized. Specific [3H]NMS binding to membrane preparations was rapid, saturable, and of high affinity. Saturation experiments revealed a single class of binding sites for the radioligand. Competition experiments with the muscarinic drugs pirenzepine, AF DX 116, dicyclomine and atropine revealed that the muscarinic receptors present on these cells are predominantly of a single class, subtype B (M2). In addition, agonist binding demonstrated existence of a GTP-sensitive high affinity binding state of the receptors. Coupling of these muscarinic receptors to the adenylate cyclase system was investigated using the muscarinic agonist carbachol which was able to inhibit the prostaglandin (PGE1)-stimulated activation of adenylate cyclase. The agonist carbachol did not stimulate the formation of IP3 above basal levels, which indicated that the receptors are not coupled to phosphatidylinositol metabolism. In conclusion, we show that possessing predominantly one subtype of muscarinic receptor, the Neuro-2A cells provide a useful model for the investigation of the heterogeneity of muscarinic receptors and the relationship of subtype to the coupling of different effectors.
Animals↗
Effect of the MHC on the immunogenicity of vascular allografts in miniature swine.
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Animals↗
Accessory and T cell defects in acquired and inherited hypogammaglobulinaemia.
Cellular defects in patients with common variable hypogammaglobulinaemia (CVH) and X-linked agammaglobulinaemia (XLA) have been studied in vitro, using a mitogen-driven system of immunoglobulin production. We have confirmed our previous finding of impaired low-density (dendritic) accessory cell function in CVH and now show that accessory cell function is normal in XLA. We demonstrate that macrophage accessory function is normal in CVH. T cell help for IgM production is also deficient in CVH, and T cell help in XLA is also abnormal for both IgG and IgM. Some XLA patients have excessive T suppressor activity. The contribution of these defects to the clinical states is discussed.
Agammaglobulinemia↗
Automated DNA sequencing methods for detection and analysis of mutations: applications to the Lesch-Nyhan syndrome.
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Base Sequence↗