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Biomedical subjects

E Skriver

Publications and source records attributed to E Skriver.

At least 19 recordsLinked to original sources
PubMed2004

The role of the RAS in programming of adult hypertension.

The aetiology of cardiovascular disease originally included two components: a genetic component and an environmental or lifestyle component. Increasing epidemiologic evidence has been accumulating during the last decades indicating the importance of a third component: the influence of the environment during foetal development. Poor living conditions resulted in a high infant mortality and influenced the incidence of cardiovascular diseases in adulthood despite better living conditions (A. Forsdahl. Br J Prev Soc Med 1977; 31, 91-95). An association between pre-natal growth pattern and the rate of death from cardiovascular disease in adulthood was reported (D.J. Barker, P.D. Winter, C. Osmond, B. Margetts & S.J. Simmonds. Lancet 1989; 2, 577-580). Men from Hartfordshire (UK), born between 1911 and 1930 were investigated. The investigations showed that men with the lowest weight at birth and at 1 year of age had the highest risks of death from cardiovascular disease (D.J. Barker, P.D. Winter, C. Osmond, B. Margetts & S.J. Simmonds. Lancet 1989; 2, 577-580). These findings suggested that factors in the perinatal environment could programme an individual for later risk of development of cardiovascular disease compared with someone born with a normal weight. Numerous studies have since confirmed these initial findings of an inverse relationship between early growth pattern and cardiovascular disease in adulthood.

Animals↗
PubMed2000

Chlamydia pneumoniae-associated ADEM.

Inflammatory demyelinating diseases are a common cause of neurologic disability in young adults, and usually the cause is unknown. We describe a case of acute disseminated encephalomyelitis (ADEM) associated with Chlamydia pneumoniae infection. An 18-year-old previously healthy women, with a one-week history of coryzal illness, was admitted because of progressive headache, dizziness, and a left-sided hemiparesis. MR imaging of the brain and brainstem showed typical signs of ADEM. The diagnosis was established by PCR Chlamydia pneumoniae DNA positivity in a tracheal swab and by increasing titres of Chlamydia IgM antibody. The patient was treated with doxycycline and steroids and recovered completely. Apart from therapeutic implications, this case may contribute to our understanding of demyelinating diseases of the central nervous system.

Adolescent↗
PubMed1997

Gliomatosis cerebri--an appropriate diagnosis? Case reports.

PURPOSE: To evaluate the premises for the diagnosis gliomatosis cerebri in relation to diffuse astrocytomas. MATERIAL AND METHODS: CT, MR images and pathological analyses were used to assess the cases of 4 patients with diffusely infiltrating astrocytic tumours that radiologically, clinically and pathologically resembled gliomatosis cerebri. RESULTS AND CONCLUSION: Some astrocytomas have an immense potential for diffuse infiltration and they would seem to be more frequent than recognized hitherto. The definition of gliomatosis cerebri as a separate entity is questionable, and a diagnosis of diffusely infiltrating astrocytoma is recommended in such cases.

Adult↗
PubMed1996

Isolation and characterization of porcine mannan-binding proteins of different size and ultrastructure.

The authors report on the purification and characterization of mannan- binding proteins (MBP) isolated from porcine serum. The MBPs were purified by use of PEG precipitation, affinity chromatography on mannan-Sepharose, protein A- and anti-porcine IgM-Sepharose followed by gel filtration. The MBP proteins were collagenase sensitive and showed gamma 1-gamma 2-electrophoretic mobility. The MBP designated pMBP-28 had a molecular mass of 28 kDa when analysed on SDS-PAGE under reducing conditions and eluted corresponding to a molecular mass of approximately 700 kDa on gel filtration chromatography. Electron micrographs of pMBP-28 revealed an oligomeric protein similar to rodent MBP-A and human MBP but with a predominance of penta- and hexameric molecules. Another protein designated pMBP-27 was composed of peptides of 27 kDa and had an Mr of 300-350 kDa on gel filtration chromatography. Electron microscopy of pMBP-27 showed dimer and trimer molecules; the trimers without distinct stalk regions. The N-terminal 26(pMBP-27) and 24(MBP-28) amino acid residues showed 54% and 58% identity with human MBP.pMBP-28 showed a higher degree of sequence similarity to rat and mouse MBP-A (60% identity) than to mouse and rat MBP-C (41-45% identity). Both pMBPs exhibited Ca2+-dependent binding to D-mannose immobilized on agarose but no significant binding to N-acetyl-D-glucosamine- or fucose-agarose. The results further suggested the presence of a third pMBP which copurified with pMBP-27 but this protein was not sequenced.

Amino Acid Sequence↗
PubMed1995

Collectin in a non-mammalian species: isolation and characterization of mannan-binding protein (MBP) from chicken serum.

A chicken serum lectin was isolated by affinity chromatography on TSK-75 beads derivatized with the monosaccharide N-acetyl-D-mannosamine (ManNAc). Serum was applied to the column in a Ca(2+)-containing buffer and proteins were eluted with EDTA. After recalcification, the eluate was passed through a new ManNAc-derivatized column. Bound proteins were eluted with 50 mM ManNAc. Anti-carbohydrate antibodies present in the eluate were removed by passage through a rabbit anti-chicken immunoglobulin derivatized column, and the lectin was further purified by ion-exchange chromatography and gel-permeation chromatography. The purified chicken lectin shows an overall structure similar to mammalian mannan-binding protein (MBP). SDS-PAGE revealed two polypeptides of M(r) 33 and 34 kDa (reduced) with identical sequence for the first 30 NH2-terminal residues. The NH2-terminal sequence shows 43% identity with the human MBP. Like mammalian MBP, the polypeptides of the chicken lectin are degraded by treatment with collagenase. Residues 26-30 (G-L-P(OH)-G-D) are likely to represent the beginning of the collagenous region. Mobilities on SDS-PAGE of the COOH-terminal collagenase-resistant fragment under reduced and non-reduced conditions indicate the presence of intrachain disulphide bonds, as are also found in mammalian MBP. Gel chromatography showed an intact mol. wt of 750 kDa. Binding of the chicken MBP to mannan was inhibited by monosaccharides in the following order of potency: ManNAc > L-fucose > mannose > N-acetylglucosamine. Other monosaccharides inhibited poorly or not at all. Chicken MBP, bound to mannan, activated the classical complement pathway in human serum. Electron micrographs show structures and dimensions resembling human MBP. Overall, the results show that the purified lectin is the chicken homologue to mammalian MBP and indicate the presence of a MBP-like clearance system outside mammals.

Amino Acid Sequence↗
PubMed1995

Mannan-binding protein forms complexes with alpha-2-macroglobulin. A protein model for the interaction.

We report that alpha-2-macroglobulin (alpha 2M) can form complexes with a high molecular weight porcine mannan-binding protein (pMBP-28). The alpha 2M/pMBP-28 complexes was isolated by PEG-precipitation and affinity chromatography on mannan-Sepharose, protein A-Sepharose and anti-IgM Sepharose. The occurrence of alpha 2M/pMBP-28 complexes was further indicated by crossed immunoelectrophoresis and by use of an anti-alpha 2M affinity column and chelating Sepharose loaded with Zn2+. The eluates from these affinity columns showed alpha 2M subunits (94 and 180 kDa) and pMBP subunits (28kDa) in SDS-PAGE, which reacted with antibodies against alpha 2M and pMBP-28, respectively, in Western blotting. Furthermore, alpha 2M/pMBP-28 complexes were demonstrated by electron microscopy. Fractionation of pMBP-containing D-mannose eluate from mannan-Sepharose on Superose 6 showed two protein peaks which reacted with anti-C1 s antibodies in ELISA, one of about 650-800 kDa, which in addition contained pMBP-28 and anti-alpha 2M reactive material, the other with an M(r) of 100-150 kDa. The latter peak revealed rhomboid molecules (7 x 15 nm) in the electron microscope and a 67 kDa band in SDS-PAGE under reducing conditions. This band was also seen in eluates from the anti-alpha 2M and chelating Sepharose columns. Based on these observations and previous findings by other investigators of a serine protease with about 67 kDa subunits which copurifies with human MBP we propose a model for the interaction of pMBP-28 with alpha 2M.

Animals↗
PubMed1992

Oligomer formation of staphylococcal alpha-toxin analyzed by electron microscopy and image processing.

The 12S oligomeric form of Staphylococcus aureus alpha-toxin has been studied with electron microscopy after incubation of the toxin with membrane preparations or liposomes. The target material originated from human platelets. Different electron microscopic preparation techniques were used including negative staining, freeze-fracture and vitrification in liquid ethane. Analysis of micrographs with image processing methods revealed two groups of ring-like structures corresponding to alpha-toxin oligomers. One form measured 75 A in diameter and had a high stain density in the central protein deficient part while the other was larger with a diameter of 100 A and less stain accumulation in the center. The conditions under which the latter were formed suggest that this corresponds to an inactive loosely-bound form of the toxin. The high stain density in the smaller particle is consistent with the presence of a penetrating pore in this structure.

Bacterial Toxins↗
PubMed1991

Characterisation of Ca2+ or Mg(2+)-dependent nucleoside triphosphatase from rat mesenteric small arteries.

When isolated rat mesenteric small arteries were submitted to 2 s of sonication, a nucleoside triphosphatase activity was released to the medium, mainly from the plasma membrane of the vascular smooth muscle cells. The activity was kinetically characterized: It hydrolysed ATP, UTP and GTP with the same substrate affinity and the same specific activity. CaATP, as well as MgATP were substrates for the enzyme with an apparent Km in the micromolar range. ATPase inhibitors: ouabain, vanadate, AlF4-, oligomycin and N-ethylmaleimide were without effect on the hydrolytic activity. Among other modifiers tested only N,N'-dicyclohexylcarbodiimide caused significant (greater than 30%) inhibition. In the presence of micromolecular concentrations of Ca2+ and Mg2+, small (less than 20 mM) concentrations of Na+, K+, Rb+, Cs+ and choline+, irrespective of the nature of the anion, activated the hydrolysis with an equilibrium ordered pattern, but concentrations of monovalent cation salts above 20 mM decreased the hydrolysis rate. No activation by monovalent cation salts was seen at millimolar concentrations of divalent cations and substrate. On the basis of the results a standard mixture is proposed, which allows a sensitive assay of the specific enzyme activity.

Adenosine Triphosphatases↗
PubMed1991

Surface areas of basolateral membranes in renal distal tubules estimated by vertical sections.

The surface area of the Na,K-ATPase-rich basolateral membranes in the medullary thick ascending limb of the distal tubule in the rabbit kidney was determined stereologically using the method of 'vertical sections', whereby unbiased surface estimates are obtained by imposing a cycloid test-lattice on micrographs of ultrathin sections cut roughly longitudinal to the tubular axis. The unbiased estimate of the surface area of basolateral membranes per tubule length in the thick ascending limb was 1.45 x 10(6) microns 2/mm. The results are compared with previous surface area measurements in this segment of the tubule and discussed with respect to the contributions from all sampling levels to the real biological variation. An optimized sampling scheme with a roughly fourfold reduction in workload is suggested.

Animals↗
PubMed1990

Coexistence of different forms of Na,K-ATPase in two-dimensional membrane crystals.

Two-dimensional membrane crystals of renal Na,K-ATPase were analyzed by electron microscopy and image processing. The particular property of the crystals in this work was that they showed unit cell parameters similar to the previously studied p21 crystals but lacked the dyad axis as observed in nominal 0 degrees-projections. A three-dimensional reconstruction revealed that structural differences between alpha beta-units of the enzyme gave rise to the asymmetry. A high degree of two-fold rotational symmetry was observed in the middle of the structure while the protein units had different three-dimensional shapes at levels above and below the central sections. The simultaneous coexistence of different forms of Na,K-ATPase suggests that the conformational flexibility of the enzyme plays an important role in the pumping process.

Animals↗
PubMed1990

[Migraine with aura (classical migraine) in patients examined for cerebrovascular disease].

Four patients were investigated for cerebrovascular origin of focal neurologic deficits. Three of the patients had persistent deficits. However, during cerebral angiography and subsequent regional cerebral blood flow (rCBF) investigation all patients developed attacks of migraine with aura. During the rCBF study focal reduction of the blood flow, typical for migraine with aura, developed in the posterior brain regions. It is concluded that vasospasm of migrainous origin might be the cause of the neurological deficits in the four patients.

Adult↗
PubMed1989

Serum albumin binding of palmitate and stearate. Multiple binding theory for insoluble ligands.

In usual studies of ligand binding to a carrier, free and bound ligand concentrations are measured in equilibrium mixtures with varying carrier and ligand concentrations. The observed data are then analyzed by a binding equation such as Scatchard's or the general binding equation. With palmitic, stearic and oleic acids as ligands we found that the aqueous solubility is too low to allow this procedure. We have consequently transformed the general binding equation so that it does not contain parameters related to aqueous solutions of the ligand. While the classical binding equations describe affinities of transfer of a ligand from an aqueous solution to the carrier, the new equation is valid for transfer of a ligand from one bound state to another, i.e. for relative binding description. The relative binding constants, L1, L2, L3 ... Li, in the new equation thus define the transfer affinity for the ligand from a 1:1 complex with a standard carrier to an i:1 complex of the ligand with the carrier investigated. Binding of palmitate and stearate to human serum albumin was studied by determination of dialytic exchange rates between identical fatty acid/albumin solutions. The results were analyzed by the new equation without reference to ligands in aqueous solution.

Chlorides↗
PubMed1989

Two-dimensional crystalline arrays of Na,K-ATPase with new subunit interactions induced by cobalt-tetrammine-ATP.

Purified membrane-bound Na,K-ATPase incubated with cobalt-tetrammine-ATP [Co(NH3)4ATP], which is a stable MgATP complex analog, shows two new types of membrane crystals, a new p21 form and a p4 form. The building blocks of the crystalline arrays correspond to (alpha beta)2 dimers of the enzyme protein suggesting that alpha-alpha interaction may be important in the pumping process.

Adenosine Triphosphate↗
PubMed1988

Three-dimensional structure of renal Na,K-ATPase determined from two-dimensional membrane crystals of the p1 form.

Electron microscopy and image processing were used to reconstruct a three-dimensional model of membrane-bound monomeric renal Na,K-ATPase from negatively stained two-dimensional crystals of the p1 type. Correlation methods were applied to obtain projection averages which were aligned by a phase difference minimization procedure. The self-consistency of the reconstruction process was high as determined by correlation between experimental projections and projections of the calculated model. The three-dimensional model of the Na,K-ATPase promoter in the p1 crystal form contains three characteristic domains, a protein dense ellipsoid, a small globular stain deficient domain, and a connecting low-contrast region. The latter is thought to correspond to the lipid-penetrating part of the Na,K-ATPase promoter. The location of this domain gives the protein an asymmetric distribution in the bilayer so that it is exposed primarily on one side proposed to correspond to the intracellular face.

Animals↗