Search PubMed⌕ Search

Biomedical subjects

S Dale

Publications and source records attributed to S Dale.

At least 19 recordsLinked to original sources
PubMed2001

Mosaic inv dup(8p) marker chromosome with stable neocentromere suggests neocentromerization is a post-zygotic event.

Marker chromosomes containing active human neocentromeres have been described in individuals where the chromosomes are non-mosaic, suggesting that they are mitotically stable, but also in individuals where there is mosaicism, raising the possibility of neocentromere instability. We report two independently ascertained individuals who are mosaic for a supernumerary marker chromosome, shown by reverse chromosome painting to have an 8p origin, resulting in mosaicism for tetrasomy 8p23.1-->pter in the patient. The markers have a primary constriction but show no detectable centromeric alpha-satellite DNA. The marker in Patient 1 demonstrated no centromere protein CENP-B binding, but associated with nine different functionally critical centromere proteins. Investigation of peripheral blood lymphocytes from this patient on five separate occasions over a 13-year period showed 23-46% mosaicism for the marker chromosome with no decrease in incidence. In vitro investigation of primary and secondary sub-clones of a lymphoblast cell line derived from the patient demonstrated 100% stability of the marker chromosome indicating that neocentromere instability is unlikely to be responsible for the mosaicism in the patient. This and other available data support a general model of neocentromerization as a post-zygotic event, irrespective of whether the supernumerary chromosome fragment has arisen during meiosis or post-fertilization at mitosis.

Adolescent↗
PubMed2001

Severe toxic osteoblastoma of the humerus associated with diffuse periostitis of multiple bones.

Toxic osteoblastoma is a rare variant of an uncommon primary bone tumour that has been described only once before in the world medical literature. It is characterised by systemic features including fever, weight loss and a striking diffuse periostitis in association with an osteoblastoma, resulting in delayed diagnosis. Early recognition of this condition could prevent inappropriate therapies and reduce morbidity.

Biopsy↗
PubMed2000

Improved assay for fecal calprotectin.

Fecal calprotectin is a marker of inflammatory and neoplastic disease in the lower gastrointestinal tract. A new fecal sample preparation procedure for the measurement of calprotectin has been developed, with higher calprotectin yield and lower contamination risk. Changes in the new method compared to the original [Roseth AG, Fagerhol MK, Aadland E, Schonsby H. Assessment of the neutrophil dominating protein calprotectin in feces. A methodologic study. Scand J Gastroenterol 1992;27(9):793-798] are smaller sample size, higher dilution of the sample, presence of dissociating agents in the extraction solution and procedure performed in closed disposable tubes. The extraction yield was 78% (41-100%) of total calprotectin, giving an overall five-fold increase compared to the original method. Samples with high calprotectin values were increased to a slightly higher degree, than low calprotectin samples, thus improving the separation between high and low calprotectin levels. Median calprotectin level in healthy subjects was 26 microg/g. Pathological samples with pancolitis showed levels up to 30000 microg/g. The mean C.V. (coefficient of variation) in blended feces was lower than that of unblended, suggesting uneven distribution of calprotectin. However, no significant difference between spot measurements was found when five samples from each of 47 stools were measured. Thus measurements of calprotectin in fecal samples were accurate and reproducible. No interference with foods or relevant oral pharmaceuticals or nutraceuticals was found.

Biomarkers↗
PubMed1998

The metallo-disintegrin ADAM10 (MADM) from bovine kidney has type IV collagenase activity in vitro.

The metallo-disintegrins (ADAMs) are a family of mammalian proteins with significant amino acid sequence identity and a domain organisation similar to the snake venom metalloproteinases (reprolysins). They have been implicated in a wide variety of processes such as cell-cell and cell matrix adhesion and proteolysis of the extracellular matrix in a wide variety of cell types. They may also be involved in events such as the processing of plasma membrane proteins, proteolysis in the secretory pathway and pro-cytokine conversion processes. Due to the close relationship of the ADAM proteins with snake venom enzymes which have been demonstrated to be type IV collagenases, we investigated whether purified bovine ADAM10 could cleave basement membrane type IV collagen. We show here that ADAM10 purified from bovine kidney can cleave a basement membrane collagen type IV preparation as assessed by SDS-PAGE analysis and novel epitope recognition with a specific antibody to type IV collagen. The demonstration that a metallo-disintegrin displays a type IV collagenase activity may be relevant to tumour metastasis and may have general relevance to extracellular re-modeling in renal pathology and a variety of other pathological states where compromise of the basement membrane is involved.

ADAM Proteins↗
PubMed1995

Bacterial expression of the catalytic domain of 3-hydroxy-3-methylglutaryl-CoA reductase (isoform HMGR1) from Arabidopsis thaliana, and its inactivation by phosphorylation at Ser577 by Brassica oleracea 3-hydroxy-3-methylglutaryl-CoA reductase kinase.

The catalytic domain of 3-hydroxy-3-methylglutaryl-CoA reductase isoform 1 (HMGR1cd) from Arabidopsis thaliana has been expressed in Escherichia coli in a catalytically active form and purified. The high efficiency of the bacterial expression system together with the simplicity of the purification procedure used in this study resulted in the attainment of large quantities of pure enzyme (about 5 mg/l culture) with a final specific activity of up to 17 U/mg. This specific activity is higher than that reported to date for any 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) purified from a plant source. HMGR1cd activity was completely blocked by the HMGR inhibitor mevinolin (IC50 = 12.5 nM). No significant differences were observed between the Km values of HMGR1cd for NADPH (71 +/- 7 microM) and (S)-3-hydroxy-3-methylglutaryl-CoA (8.3 +/- 1.5 microM) and those of pure HMGR preparations obtained from different plant sources. The purified HMGR1cd was reversibly inactivated by phosphorylation at a single site by Brassica oleracea HMGR kinase A, which is functionally related to the mammalian AMP-activated protein kinase. The site of phosphorylation is Ser577 in the complete sequence of A. thaliana HMGR1. The results in this paper represent the first evidence that a higher plant HMGR is regulated by direct phosphorylation, at least in a cell-free system. Our results also reinforce the view that the AMP-activated protein kinase/SNF1 family is an ancient and highly conserved protein kinase system.

AMP-Activated Protein Kinases↗
PubMed1995

Similar substrate recognition motifs for mammalian AMP-activated protein kinase, higher plant HMG-CoA reductase kinase-A, yeast SNF1, and mammalian calmodulin-dependent protein kinase I.

We have analysed phosphorylation of the synthetic peptide AMARAASAAALARRR, and 23 variants by mammalian, higher plant and yeast members of the SNF1 protein kinase subfamily (AMP-activated protein kinase (AMPK), HMG-CoA reductase kinase (HRK-A), and SNF1 itself), and by mammalian calmodulin-dependent protein kinase I (CaMKI). These four kinases recognize motifs which are very similar, although distinguishable. Our studies define the following recognition motifs: AMPK: phi (X beta)XXS/TXXX phi; HRK-A: phi (X,beta)XXSXXX phi; Snf1: phi XRXXSXXX phi; CaMKI: phi XRXXS/TXXX phi; where phi is a hydrophobic residue (M, V, L, I or F) and beta is a basic residue (R, K or H).

AMP-Activated Protein Kinases↗
PubMed1994

Biochemical characterization of two forms of 3-hydroxy-3-methylglutaryl-CoA reductase kinase from cauliflower (Brassica oleracia).

We recently reported the existence of a protein kinase cascade in higher plants, of which the central component is a 3-hydroxy-3-methylglutaryl(HMG-)-CoA reductase kinase functionally related to mammalian AMP-activated protein kinase [MacKintosh, R. W., Davies, S. P., Clarke P. R., Weekes, J., Gillespie, S. G., Gibb, B. J. & Hardie, D. G. (1992) Eur. J. Biochem. 209, 923-931]. We have now purified this protein kinase 9000-fold from cauliflower inflorescences. During the course of this work we noticed a second minor form (form B) which separated from the major form (A) on ion exchange and gel filtration. Both forms phosphorylate the catalytic fragment of mammalian HMG-CoA reductase. Both forms are markedly inactivated by incubation with the reactive ATP analogue p-fluorosulphonylbenzoyl adenosine (FSO2PhCOAdo), and also by mammalian protein phosphatase 2C, indicating that form B, like form A, is activated by phosphorylation. Form A has an apparent native molecular mass of 200 kDa by gel filtration and, after labelling with [14C]FSO2PhCOAdo, of 150 kDa by electrophoresis in non-denaturing gels. The catalytic subunit was identified as a polypeptide of 58 kDa after labelling with [14C]FSO2PhCOAdo. Form B has an apparent native molecular mass of 45 kDa by gel filtration, and was identified as a polypeptide of 45 kDa after labelling with [14C]FSO2PhCOAdo and [gamma-32P]ATP. Using a series of variants of the synthetic peptide substrate, the substrate specificities of the two forms are similar but not identical. Form B does not appear to be a proteolytic fragment of form A, and we therefore propose that it represents a closely related member of the same protein kinase sub-family.

AMP-Activated Protein Kinases↗
PubMed1994

Comparison of three D-dimer assays for the diagnosis of DVT:ELISA, latex and an immunofiltration assay (NycoCard D-Dimer).

Ninety-two consecutive patients referred for suspicion of deep venous thrombosis (DVT) were analyzed for D-dimer using ELISA, latex test, and a new immunofiltration method (NycoCard D-Dimer). Contrast venography verified the diagnosis in 40, and excluded the diagnosis in 52 patients. The sensitivity, negative predictive values, specificity and positive predictive values were, for ELISA 98%, 95%, 38% and 54, for NycoCard D-Dimer 100%, 100%, 42% and 57% and for the latex test 73%, 78%, 75%, and 69%, respectively. Sensitivity and specificity were inversely related with increasing pathological cut-off value. Comparison of test results by concentration category revealed a good agreement between ELISA and NycoCard D-Dimer, but to less extent between latex and the two other tests. It is concluded that NycoCard D-Dimer and D-dimer ELISA are well-suited as exclusion tests for DVT. A plasma sample is tested with NycoCard D-Dimer in less than 2 min. Thus, this test combines advantageous analytical properties comparable to the ELISA-test, with rapidity and simplicity comparable to the latex test.

Adult↗
PubMed1993

Assay of D-dimer based on immunofiltration and staining with gold colloids.

In this immunofiltration assay of D-dimer in plasma samples, the antigens are captured by a monoclonal antibody on a porous membrane, and labeled with the same antibody conjugated to gold colloids. The assay time is < 2 min, and a color of intensity proportional to the concentration of D-dimer is left on the membrane. The reference range (mean +/- 2 SD) was 0.336 +/- 0.133 mg/L (n = 69). Linearity was found up to 10 mg/L. Comparison with ELISA results (x) for 198 patients' samples demonstrated a linear regression equation of y = 0.99(+/- 0.05)x + 0.68(+/- 0.07) and a mean square error of 0.503. Comparison of visual reading of the color signal (y) vs reflectometric measurements (x) for 220 patients' samples demonstrated a linear regression equation of y = 2.5(+/- 0.06)x -0.22(+/- 0.04) and a mean square error of 0.095. Bilirubin, hemoglobin, fibrinogen, soluble fibrin, and fibrinogen degradation products and freezing/thawing of samples did not interfere. Some interference from rheumatoid factor, heparin, and the presence of cells or large lipid particles was seen. The variance (CV) was 8-12% within run, 10-18% between runs, and 13-20% between persons. The new assay constitutes a rapid and reliable analytical tool combining simplicity equivalent to that of latex tests with analytical information approaching that of ELISA.

Drug Stability↗
PubMed1992

Pronuclear, cleavage and blastocyst histories in the attempted preimplantation diagnosis of the human hydatidiform mole.

We report a study of fertilization, syngamy and embryonic development in 14 oocytes from a woman with four previous pregnancies involving complete hydatidiform moles. Serial observations of pronuclear movements and syngamy were compared to those in a group of 10 multipronucleate embryos from other patients. One embryo and possibly two others developed normally or near-normally. The others displayed immediate cleavage or had one or three pronuclei. The tripronucleate eggs displayed various anomalous forms of growth. The unipronucleate eggs passed through a double form of syngamy, which might have involved chromosome doubling, and could have developed as androgenetic diploids. We suggest a hypothesis to explain these unusual observations.

Adult↗
PubMed1992

Identification of DNA sequences flanking the breakpoint of human t(14q21q) Robertsonian translocations.

We have employed molecular probes and in situ hybridization to investigate the DNA sequences flanking the breakpoint of a group of t(14q21q) Robertsonian translocations. In all the families studied, the probands were patients with Down syndrome who carried a de novo t(14q21q) translocation. The DNA probes used were two alphoid sequences, alphaRI and alphaXT, which are specific for the centromeres of chromosomes 13 and 21 and of chromosomes 14 and 22, respectively; a satellite III sequence, pTRS-47, which is specific for the proximal p11 region of chromosomes 14 and 22; and a newly defined satellite III DNA, pTRS-63, which is specific for the distal p11 region of chromosome 14. The two alphoid probes detected approximately the same amount of autoradiographic signal on the translocated chromosomes as was expected for chromosomes 14 and 21 of the originating parent, suggesting that there has been no loss of these centromeric sequences during the translocation events. Results with the two satellite III probes indicated that the domain corresponding to pTRS-47 was retained in the translocated chromosomes, whereas the domain for pTRS-63 was lost. These results have allowed us to place the translocation breakpoint between the pTRS-47 and pTRS-63 domains within the p11 region of chromosome 14.

Autoradiography↗
PubMed1991

Duplications of the X chromosome in males: evidence that most parts of the X chromosome can be active in two copies.

We have analysed two duplications of the X chromosome in male patients using chromosome replication and DNA methylation patterns as determinants of the functional status of the duplicated segments. In both cases, the large duplicated regions, Xq12-q22 and Xq26.3-qter, were not inactivated. A review of previously reported male cases revealed that these duplications were also not subject to inactivation. Taken together, the examined duplications cover almost the entire X chromosome except the pericentromeric region and Xq25-26. Thus, most regions of the X chromosome can be present in two functional copies without lethal consequences.

Blotting, Southern↗
PubMed1991

Autoantibodies in primary biliary cirrhosis: analysis of reactivity against eukaryotic and prokaryotic 2-oxo acid dehydrogenase complexes.

Six components of the mammalian 2-oxo acid dehydrogenase complexes have previously been identified as M2 autoantigens in primary biliary cirrhosis. In this report, we present data showing that both polypeptide-specific and cross-reacting antibodies are present in patients' sera. Antibodies reacting with E2 of the pyruvate dehydrogenase complex cross-react with protein X but not with any other mammalian antigen. The main immunogenic region on protein X has been localized to within its single lipoyl domain. Polypeptide-specific antibodies bind to E1 alpha and E1 beta of the pyruvate dehydrogenase complex. Antibodies reacting with the E2 polypeptides of the 2-oxoglutarate dehydrogenase complex and branched-chain 2-oxo acid dehydrogenase complex show some cross-reactivity but do not recognize any of the antigens of the pyruvate dehydrogenase complex. Antibodies against the E2 component of the mammalian pyruvate dehydrogenase complex cross-react effectively with the corresponding protein from yeast but not with E2 from Escherichia coli. Antibody titer against mammalian antigens is significantly higher than against the bacterial antigens, arguing against a bacterial origin for primary biliary cirrhosis.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
PubMed1991

Nurse, is it ME? Understanding myalgic encephalomyelitis.

Ignored or dismissed for years, myalgic encephalomyelitis (ME) is now recognised as a genuine illness, and sufferers are recommended strict rest until the symptoms of the virus subside. Public understanding of ME is still uncertain, and nurses are ideally placed to provide practical information and support.

Counseling↗