Search PubMed⌕ Search

Biomedical subjects

T Andersson

Publications and source records attributed to T Andersson.

At least 289 records · Page 16Linked to original sources
PubMed1983

Molecular weight distribution of hyaluronic acid of human synovial fluid in rheumatic diseases.

New methods to isolate and characterize the molecular weight distribution of hyaluronic acid have been applied to human synovial fluids from arthritic patients. Considerable variations in molecular weight distribution were found between the individual fluids. These methods facilitate a detailed characterization of hyaluronic acid--a prerequisite for understanding the role of hyaluronic acid for normal joint function and to evaluate the therapeutic use of local application in joint diseases.

Adult↗
PubMed1983

Clonidine promotes the accumulation of 45Ca in pancreatic beta-cell organelles.

Glucose-stimulated insulin release from pancreatic islets of ob/ob-mice was inhibited by 10(-9) M of the alpha 2-adrenergic agonist clonidine. This inhibitory effect was abolished by 10(-7) M of the antagonist yohimbine. Loading the islets with 45Ca during the clonidine exposure followed by isolation of subcellular fractions under conditions known to minimize the 45Ca redistribution resulted in increased accumulation of the isotope in the mitochondrial and microsomal fractions. It is suggested that clonidine inhibits glucose-stimulated insulin release by increasing the organelle sequestration of Ca2+.

Animals↗
PubMed1982

Characterization of the Ca2+ binding sites of calmodulin from bovine testis using 43Ca and 113Cd NMR.

The exchange rates of Ca2+ ions to the two classes of sites on calmodulin have been determined from the temperature dependence of the 43Ca NMR line width. The exchange rates were found to differ by a factor of about 40 at room temperature. The apparent pK value for one of these classes was estimated from the pH dependence of the 43Ca line width. The pK values of the two-high-affinity sites were found to differ about 0.1-1. Zn2+ ions were shown to bind to calmodulin and affect the exchange rates of Ca2+ and Cd2+ for all four sites.

Animals↗
PubMed1982

Characterization of cation-binding sites on Panulirus interruptus hemocyanin by 43Ca and 23Na NMR.

The binding of Na+ and Ca2+ ions to Panulirus interruptus hemocyanin has been studied by nuclear magnetic resonance. The combined use of 43Ca and 23Na NMR has allowed two different classes of sites to be distinguished. The sites are characterized by a relatively fast chemical exchange, local mobility and binding constants of the order of 10(3)-10(4) M-1 for Ca2+ and Mg2+ and approximately equal to 10(2) M-1 for Na+. These features and the observed pH dependence of the Ca2+ binding are consistent with the protein ligands being carboxylate groups, some of which may occur in clusters.

Binding Sites↗
PubMed1982

beta 1-and beta 2-adrenoceptor stimulatory effects of prenalterol.

Prenalterol, previously characterized as a functionally cardioselective partial beta-adrenoceptor agonist, was shown to relax K+ -elicited contractures in the uterine muscle from progesterone pretreated rats (pD2 7.7) and to increase beating rate in the rat right atrium (pD2 8.0) at about the same concentrations with maximal effects corresponding to 94 and 82% respectively of those of isoproterenol. Terbutaline, with equal maximal effects as isoproterenol, was 50 times more potent in the uterus (pD2 7.8) than in the right atrium (pD2 6.1). Both tissues displayed a high sensitivity to isoproterenol (pD2 9.1 in both tissues) indicating large receptor reserves for the full agonist. The maximal relaxing effect of prenalterol in the uterus was obtained at about a three-fold increase of the cyclic AMP content, which is similar to that obtained with isoproterenol at a corresponding relaxation. The effects in the uterine muscle of all three agonists were mediated through beta 2-adrenoceptors since beta 2-adrenoceptor blockers (ICI 118, 551 and IPS 339) antagonized the effects in concentrations which had only marginal effects on the atrial responses of the agonists. The beta 1-antagonists pafenolol and pamatolol in concentrations higher than those, which blocked the effects of the agonists on beating rate, were devoid of inhibitory effects in the uterus. These results indicate that prenalterol possesses the ability to elicit a functional response by stimulation of either beta 1-or beta 2-adrenoceptors provided that the tissue has a large spare receptor reserve for full agonists.

Adrenergic beta-Agonists↗
PubMed1982

A clinical study of the Guillain-Barré Syndrome.

60 consecutive patients (age 15-77 years) with the Guillain-Barré syndrome were studied. 37 subjects had an antecedent infection. Onset occurred with motor and/or sensory limb symptoms in 56 cases; 4 subjects experienced onsets with pain, diplopia or bladder disturbances. The motor symptoms reached a maximum within 42 days in all cases, 87% within less than 20 days. All patients had limb-muscle weakness at the symptomatic maximum: 50% exhibited cranial-nerve affections and 10 subjects has respiratory insufficiency. Signs of a remission appeared within 60 days after onset in all cases surviving the maximal phase, 81% within less than 40 days. The CSF protein concentration was elevated (0.6-7.8 g/l) in 95% of the patients; an increased mononuclear cells count 6-60 X 10(6)/l) occurred in 27% of cases. Electrophysiological abnormalities were detected in 42 out of 43 examined cases. Totally there were 4 deaths, all caused by cardiac or thrombo-embolic events. Surviving patients had restitutions without functionally significant sequelae within less than 6 months after onset in 73% of cases; all but 2 of the remaining patients recovered within 18 months. The degree of muscle weakness at maximum was the predominant prognostic factor.

Adolescent↗
PubMed1982

Amounts and distribution of intracellular magnesium and calcium in pancreatic beta-cells.

beta-Cell-rich pancreatic islets were incubated for 60-120 min in the presence of 1 mM or 20 mM glucose and analysed with regard to their contents of magnesium and calcium and how these elements were distributed among subcellular fractions. The islets contained 42 mmol magnesium per kg protein with as much as 70 mmol per kg protein in the microsomal fraction. Both the total amount and intracellular distribution of magnesium remained unaffected after raising the glucose concentration of the incubation medium. The islet content of calcium was twice as high as that of magnesium, the mitochondria and secretory granules accounting for most of the calcium in the sedimentable fractions. In both organelles a substantial fraction of calcium was exchangeable as indicated from the incorporation of 45Ca during 90 min of incubation of the islets. When raising the glucose concentration to 20 mM the percentage exchange of calcium increased from 10 to 27 in the mitochondria and from 13 to 28 in the secretory granules. The glucose stimulation of 45Ca uptake was not associated with a statistically significant increase in the total amounts of calcium. However, in addition to stimulating calcium/calcium exchange, it cannot be excluded that glucose also induces a net accumulation of intracellular calcium in the beta-cells.

Animals↗
PubMed1982

Observation of the 43Ca NMR signals from Ca2+ ions bound to calmodulin, parvalbumin, and troponin C.

Through the combined use of isotopically enriched 43Ca2+, high magnetic field, Fourier transform techniques, and a high-performance probe, the 43Ca NMR signals from ions bound to three proteins have been observed. These proteins are calmodulin, parvalbumin, and troponin C. Both longitudinal (1/T1) and transverse (1/T2) relaxation rates were measured for protein-bound 43Ca2+, and the quadrupole coupling constant and correlation time were obtained from these data. The calculated correlation times are in good agreement with the rotational correlation time for the entire protein molecules, which indicates that the Ca2+-binding sites are relatively rigid.

Animals↗
PubMed1981

Calcium and pancreatic beta-cell function. 12. Modification of 45Ca fluxes by excess of K+.

Glucose stimulation of insulin release is supposed to result from depolarization of the pancreatic beta-cells with subsequent influx of Ca2+. Isolated islets from non-inbred ob/ob-mice were employed for elucidating whether the glucose effects on the beta-cell handling of Ca2+ could be simulated by the depolarization evoked by excess of K+. Addition of 25 mM K+ was as effective as 20 mM glucose in stimulating the intracellular uptake of 45Ca. In both instances the additional amounts of incorporated 45Ca appeared in the mitochondria and the secretory granules. When analysing the washout pattern for 45Ca it was evident that the effects of raising K+ differed from those evoked by glucose. Whereas glucose inhibited 45Ca efflux during perifusion with Ca2+-deficient medium the addition of K+ resulted in a slight stimulation. Furthermore, the 45Ca incorporated in response to K+ was more readily mobilised.

Animals↗