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Biomedical subjects

T Jordan

Publications and source records attributed to T Jordan.

At least 19 recordsLinked to original sources
PubMed2001

Noninvasive ventilation allows gastrostomy tube placement in patients with advanced ALS.

The use of noninvasive positive pressure ventilation for ventilatory support during percutaneous endoscopic gastrostomy (PEG) tube placement is described in five patients with advanced ALS, four having significant bulbar symptoms. No respiratory complications occurred in any of these patients, who were considered to be at high risk for PEG placement because of severe ventilatory impairment and might not otherwise have been considered for this procedure.

Adult↗
PubMed2001

HTLV antibody screening using mini-pools.

At the present time, the UK blood transfusion services do not screen blood donations for anti-HTLV. This presentation describes a pilot study to ascertain the feasibility of HTLV antibody screening using mini-pools and also provides an estimate of HTLV prevalence within our donor population in Scotland and Northern Ireland. The Abbott/Murex HTLV I/II GE80/81 ELISA was selected for the trial. Thirty confirmed HTLV positive library samples were tested at various dilutions and five were shown to be nonreactive at a dilution of 1:100. Residues of mini-pools (of up to 95 individual donations) prepared for HCV NAT testing were tested with the Abbott/Murex GE80/81 assay. Of 6666 mini-pools (equivalent to 570 609 donations) tested, six were repeatedly reactive. All six mini-pools were confirmed HTLV antibody positive by line immunoassay. Four were confirmed to be HTLV-I positive, one HTLV-II positive and one HTLV positive (unable to type). Dilutions (1:100) of the five HTLV "nonreactive" positive samples were included in each test plate and used to determine a grey-zone cut-off. Using this grey-zone system an additional six (0.09%) mini-pool samples gave repeatedly reactive grey-zone results, none of which were confirmed. The minimum Scottish/Irish HTLV donor prevalence was shown to be 1:95 000.

Blood Donors↗
PubMed2001

A novel keratocan mutation causing autosomal recessive cornea plana.

PURPOSE: Mutations in keratocan (KERA), a small leucine-rich proteoglycan, have recently been shown to be responsible for cases of autosomal recessive cornea plana (CNA2). A consanguineous pedigree in which cornea plana cosegregated with microphthalmia was investigated by linkage analysis and direct sequencing. METHODS: Linkage was sought to polymorphic microsatellite markers distributed around the CNA2 and microphthalmia loci (arCMIC, adCMIC, NNO1, and CHX10) using PCR and nondenaturing polyacrylamide gel electrophoresis before KERA was directly sequenced for mutations. RESULTS: Positive lod scores were obtained with markers encompassing the CNA2 locus, the maximum two-point lod scores of 2.18 at recombination fraction theta = 0 was obtained with markers D12S95 and D12S327. Mutation screening of KERA revealed a novel single-nucleotide substitution at codon 215, which results in the substitution of lysine for threonine at the start of a highly conserved leucine-rich repeat motif. Structural modeling predicts that the motifs are stacked into an arched beta-sheet array and that the effect of the mutation is to alter the length and position of one of these motifs. CONCLUSIONS: This report describes a novel mutation in KERA that alters a highly conserved motif and is predicted to affect the tertiary structure of the molecule. Normal corneal function is dependent on the regular spacing of collagen fibrils, and the predicted alteration of the tertiary structure of KERA is the probable mechanism of the cornea plana phenotype.

Child↗
PubMed2000

Chromosomal duplication involving the forkhead transcription factor gene FOXC1 causes iris hypoplasia and glaucoma.

The forkhead transcription factor gene FOXC1 (formerly FKHL7) is responsible for a number of glaucoma phenotypes in families in which the disease maps to 6p25, although mutations have not been found in all families in which the disease maps to this region. In a large pedigree with iris hypoplasia and glaucoma mapping to 6p25 (peak LOD score 6.20 [recombination fraction 0] at D6S967), no FOXC1 mutations were detected by direct sequencing. However, genotyping with microsatellite repeat markers suggested the presence of a chromosomal duplication that segregated with the disease phenotype. The duplication was confirmed in affected individuals by FISH with markers encompassing FOXC1. These results provide evidence of gene duplication causing developmental disease in humans, with increased gene dosage of either FOXC1 or other, as yet unknown genes within the duplicated segment being the probable mechanism responsible for the phenotype.

Chromosomes, Human, Pair 6↗
PubMed2000

A survey of basic life support training in various undergraduate health care professions.

Basic life support (BLS) is a core skill in which all healthcare professionals should be proficient. It is logical to provide BLS training during undergraduate years ensuring basic competence in all graduating healthcare students. Previous surveys of medical and dental schools have highlighted deficiencies in BLS training. This survey sought to assess the level of BLS training provided for students across a broad range of disciplines in the North West region of the UK. This included courses leading to an entry qualification into medicine, dentistry, nursing, midwifery or a profession allied to medicine (PAM). Information was collected by self-administered postal questionnaire with a response rate of 87%. The survey highlighted major variations in BLS training provided at undergraduate level across disciplines.

Adult↗
PubMed2000

A novel locus for Leber congenital amaurosis (LCA4) with anterior keratoconus mapping to chromosome 17p13.

PURPOSE: A two-generation consanguineous Pakistani family with autosomal recessive Leber congenital amaurosis (LCA, MIM 204,000) and keratoconus was identified. All affected individuals have bilateral keratoconus and congenital pigmentary retinopathy. The goal of this study was to link the disease phenotype in this family. METHODS: Genomic DNA was amplified across the polymorphic microsatellite poly-CA regions identified by markers. Polymerase chain reaction (PCR) products were separated by nondenaturing polyacrylamide gel electrophoresis. Alleles were assigned to individuals, which allowed calculation of LOD scores using the Cyrillic and MLINK software program. The retinal guanylate cyclase (RETGC-1, GDB symbol GUC2D) and pigment epithelium-derived factor (PEDF) genes were analyzed by heteroduplex analysis and direct sequencing for mutations in diseased individuals. RESULTS: Based on a whole genome linkage analysis the first locus for this combined phenotype has been mapped to chromosome 17p13. Linkage analysis gave a two point LOD score of 3.21 for marker D17S829. Surrounding this marker is a region of homozygosity of 15.77 cM, between the markers D17S1866 and D17S960; however, the crossover for the marker D17S1529 refines the region to 10.77 cM within which the disease gene is predicted to lie. Mutation screening of the nearby RETGC-1 gene, which has been shown to be associated with LCA1, revealed no mutations in the affected individuals of this family. Similarly, another prime candidate in the region PEDF was also screened for mutations. The factor has been shown to be involved in the photoreceptor differentiation and neuronal survival. No mutations were found in this gene either. Furthermore, RETGC-1 was physically excluded from the critical disease region based on the existing physical map. CONCLUSIONS: It is therefore suggested that this combined phenotype maps to a new locus and is due to an as yet uncharacterized gene within the 17p13 chromosomal region.

Blindness↗
PubMed1998

Mutations of the forkhead/winged-helix gene, FKHL7, in patients with Axenfeld-Rieger anomaly.

Genetic linkage, genome mismatch scanning, and analysis of patients with alterations of chromosome 6 have indicated that a major locus for development of the anterior segment of the eye, IRID1, is located at 6p25. Abnormalities of this locus lead to glaucoma. FKHL7 (also called "FREAC3"), a member of the forkhead/winged-helix transcription-factor family, has also been mapped to 6p25. DNA sequencing of FKHL7 in five IRID1 families and 16 sporadic patients with anterior-segment defects revealed three mutations: a 10-bp deletion predicted to cause a frameshift and premature protein truncation prior to the FKHL7 forkhead DNA-binding domain, as well as two missense mutations of conserved amino acids within the FKHL7 forkhead domain. Mf1, the murine homologue of FKHL7, is expressed in the developing brain, skeletal system, and eye, consistent with FKHL7 having a role in ocular development. However, mutational screening and genetic-linkage analyses excluded FKHL7 from underlying the anterior-segment disorders in two IRID1 families with linkage to 6p25. Our findings demonstrate that, although mutations of FKHL7 result in anterior-segment defects and glaucoma in some patients, it is probable that at least one more locus involved in the regulation of eye development is also located at 6p25.

Amino Acid Sequence↗
PubMed1997

Familial glaucoma iridogoniodysplasia maps to a 6p25 region implicated in primary congenital glaucoma and iridogoniodysgenesis anomaly.

Familial glaucoma iridogoniodysplasia (FGI) is a form of open-angle glaucoma in which developmental anomalies of the iris and irido-corneal angle are associated with a juvenile-onset glaucoma transmitted as an autosomal dominant trait. A single large family with this disorder was examined for genetic linkage to microsatellite markers. A peak LOD score of 11.63 at a recombination fraction of 0 was obtained with marker D6S967 mapping to chromosome 6p25. Haplotype analysis places the disease gene in a 6.4-cM interval between the markers D6S1713 and D6S1600. Two novel clinical appearances extend the phenotypic range and provide evidence of variable expressivity. The chromosome 6p25 region is now implicated in FGI, primary congenital glaucoma, and iridogoniodysgenesis anomaly. This may indicate the presence of a common causative gene or, alternatively, a cluster of genes involved in eye development/function.

Chromosome Mapping↗
PubMed1996

A competitive chemiluminescent enzyme-linked immunosorbent assay for the determination of RMP-7 in human blood.

RMP-7, a bradykinin agonist, is a synthetic nonapeptide designed to enhance the delivery of therapeutics to the central nervous system. A sensitive, competitive chemiluminescent enzyme-linked immunosorbent assay (ELISA) for quantifying RMP-7 in human blood samples has been developed. Rabbit antibodies against RMP-7 were produced using the conjugate of RMP-7 to keyhole limpet hemocyanin through glutaraldehyde. Biotinylated RMP-7, conjugated via N-hydroxysuccinimide ester, was used as the tracer. A premixed solution of biotinylated alkaline phosphatase and avidin was used to quantify the tracer, with a dioxetane-based compound as the chemiluminescent substrate. The method involves treating blood samples with organic solvents to precipitate proteins, evaporating the supernatants to dryness, reconstituting residues in PBS and assaying the buffer solutions with the ELISA. The assay, using 1.0 ml of whole blood, has precision and accuracy within +/- 20% over the concentration range 25-800 pg ml-1. There are no significant endogenous interferences. The assay has been successfully used to support clinical trials of RMP-7.

Alkaline Phosphatase↗
PubMed1996

Clinical features of experimentally induced rabies in cattle and sheep.

A total of 20 cattle and five sheep out of a larger group of animals that were experimentally challenged with virus as part of the required protocol for a vaccine trial developed clinical signs of rabies. All five sheep and 18 of the cattle tested positive for rabies in a direct fluorescent antibody (FA) test. The remaining two cattle had suspicious FA results. Prospective observations are reported in this study. In the diseased cattle, the average incubation period was 15.1 days and the average morbidity period was 3.7 days. Of those, the naive cattle had significantly shorter incubation and morbidity periods than the test-vaccinated cattle. Major clinical signs included excessive salivation (100%), behavioural change (100%), muzzle tremors (80%), vocalization (bellowing; 70%), aggression, hyperaesthesia and/or hyperexcitability (70%), and pharyngeal paresis/paralysis (60%). The furious form of rabies was seen in 70% of the cattle. In the diseased sheep, the average incubation period was 10.0 days and the average morbidity period was 3.25 days. Major clinical signs included muzzle and/or head tremors (80%), aggressiveness, hyperexcitability, and/or hyperaesthesia (80%), trismus (60%), salivation (60%), vocalization (60%) and recumbency (40%). The furious form of rabies manifested in 80% of the sheep. Current rabies vaccines on the market contain higher effective doses than that utilized for the test vaccine and the results of this study do not reflect in any way on commercially available ruminant rabies vaccines.

Animals↗
PubMed1996

Clinical presentation of experimentally induced rabies in horses.

Twelve naive and nine test-vaccinated horses which developed clinical signs of rabies as a result of the required protocol of a vaccine trial were prospectively observed. Nineteen of the 21 cases were confirmed positive for rabies infection of the brain by fluorescent antibody test. The two horses with negative results had ganglioneuritis of the trigeminal ganglion or lymphocytic perivascular cuffing in the brain stem in addition to clinical signs. Average incubation period was 12.3 days and average morbidity was 5.5 days. Naive animals had significantly shorter incubation and morbidity periods (P < 0.05). Muzzle tremors were the most frequently observed (81%) and most common initial sign. Other common signs were pharyngeal spasm or pharyngeal paresis (71%), ataxia or paresis (71%), lethargy or somnolence (71%). The furious form was manifested in 43% of rabid horses and some of these furious animals initially manifested the dumb form. The paralytic form was not observed. Histopathology was characteristics for rabies. The results of this trial do not reflect on the efficacy of commercially licensed equine rabies vaccines.

Animals↗
PubMed1996

Peters' anomaly.

Explore the source record for details and available documents.

Animals↗
PubMed1996

Preparation and measurement of artificial enamel lesions, a four-laboratory ring test.

Transversal microradiography is the most widely accepted method used to study changes in mineral content profiles. In spite of its widespread use, relatively little information is available on its validity and reproducibility. Following the recommendation of the Consensus Conference on Intraoral Model Systems, this study was designed to explore reproducibility of lesion analysis within a laboratory and comparability of analysis among various laboratories. Incipient enamel lesions were produced by four research groups using both a common ('standard') and a local ('preferred') protocol. Sections were produced by each group and allocated to 'mixed' bags of specimens, which were analysed by the groups. With the chosen scheme some sections were analysed six times by the same group (as an internal reference standard) while others were analysed by all four groups. The data for the mineral content profiles were expressed as the integrated mineral loss (IML) value and lesion depth. The results showed the lesions produced with the standard protocol to be in the range 2,000-3,000 vol% mineral x microns for IML. The IML of the lesions produced with the preferred protocol varied between 1,800 and 6,300 vol% mineral x microns. Variation in IML values could be attributed to the biological variation between lesions, but also to time (of microradiograph production) and measurement effects, calibration of the magnification of the specimens, and the parameters used in the algorithm to calculate IML. Some of these parameters also affected the lesion depth. It is advised to standardise (or at least report) the method of calculation of IML, and to include a reference lesion between analyses in a longitudinal study as an internal standard. With the data produced, it was calculated that the number of lesions required to differentiate between preventive treatments varied substantially among laboratories. The recommendations given will improve the power of the screening methods for caries-preventive agents for which microradiography is an essential analytical method.

Analysis of Variance↗
PubMed1995

Ultraviolet resonance Raman spectroscopy of delta 5-3-ketosteroid isomerase revisited: substrate polarization by active-site residues.

The delta 5-3-ketosteroid isomerase (EC 5.3.3.1) of Pseudomonas testosteroni promotes extremely rapid conversion of delta 5- to delta 4-3-ketosteroids by a conservative intramolecular proton transfer via an enolic intermediate. The competitive inhibitor 19-nortestosterone displays marked spectroscopic changes upon binding to the enzyme, but the mechanisms responsible for these changes have not been unequivocally established. Ultraviolet resonance Raman (UVRR) spectra are reported for 19-nortestosterone in acid solutions and for this ligand when bound to delta 5-3-ketosteroid isomerase, as well as to its D38N and Y14F/D38N mutants. The frequencies of UVRR bands associated with C = O and C = C stretching can be used to monitor the state of polarization of the enone fragment of the steroid and the effects of the catalytic side chains, Tyr-14 and Asp-38, on these polarizations. Strong polarization is indicated by marked frequency downshifts of the C = O and C = C bands in the native protein; the downshifts are diminished by the mutations of these catalytic residues. The lower polarizing effects of the Y14F and D38N single mutants and the Y14F/D38N double mutant indicate that most of the polarization of the conjugated ketone is attributable to hydrogen-bond donation by the hydroxyl group of Tyr-14. A smaller contribution of Asp-38 is detected which is, in part, cooperative with that of Tyr-14. Reference spectra of hydrogen-bonded and protonated forms of 19-nortestosterone are reassigned, on the basis of the species identification of D. C. Hawkinson and R. M. Pollack [(1993) Biochemistry 32, 694-698].(ABSTRACT TRUNCATED AT 250 WORDS)

Binding Sites↗
PubMed1995

Secondary and tertiary structure of the A-state of cytochrome c from resonance Raman spectroscopy.

Ferricytochrome c can be converted to the partially folded A-state at pH 2.2 in the presence of 1.5 M NaCl. The structure of the A-state has been studied in comparison with the native and unfolded states, using resonance Raman spectroscopy with visible and ultraviolet excitation wavelengths. Spectra obtained with 200 nm excitation show a decrease in amide II intensity consistent with loss of structure for the 50s and 70s helices. The 230-nm spectra contain information on vibrational modes of the single Trp 59 side chain and the four tyrosine side chains (Tyr 48, 67, 74, and 97). The Trp 59 modes indicate that the side chain remains in a hydrophobic environment but loses its tertiary hydrogen bond and is rotationally disordered. The tyrosine modes Y8b and Y9a show disruption of tertiary hydrogen bonding for the Tyr 48, 67, and 74 side chains. The high-wavenumber region of the 406.7-nm resonance Raman spectrum reveals a mixed spin heme iron atom, which arises from axial coordination to His 18 and a water molecule. The low-frequency spectral region reports on heme distortions and indicates a reduced degree of interaction between the heme and the polypeptide chain. A structural model for the A-state is proposed in which a folded protein subdomain, consisting of the heme and the N-terminal, C-terminal, and 60s helices, is stabilized through nonbonding interactions between helices and with the heme.

Animals↗