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Biomedical subjects

M Joelsson

Publications and source records attributed to M Joelsson.

11 recordsLinked to original sources
PubMed2001

Allopurinol as prophylaxis against pouchitis following ileal pouch-anal anastomosis for ulcerative colitis. A randomized placebo-controlled double-blind study.

BACKGROUND: Pouchitis is the major long-term complication of restorative proctocolectomy for ulcerative colitis (UC). Allopurinol is a scavenger of oxygen-derived free radicals, which it is suggested play a role in the development of UC and pouchitis. The first aim was to test the hypothesis that the incidence of pouchitis can be reduced by prophylactic Allopurinol, and secondly to evaluate if Allopurinol influences the overall pouch function. METHODS: 273 patients with UC who were planned for proctocolectomy and ileal pouch-anal anastomosis at 12 centres in Sweden between October 1994 and June 1997 were offered the opportunity to participate. 184 patients (67%) were randomized to receive postoperative prophylactic Allopurinol 100 mg twice daily or placebo. All 273 patients had clinical and endoscopic follow-up at 1, 3, 6, 12, 18, 24 months after surgery. RESULTS: Of the 184 randomized patients, 94 were randomized to Allopurinol and 90 to placebo; 116 patients (63%) completed follow-up and the crude incidence of pouchitis among those patients fullfilling the protocol was 31% in the Allopurinol group and 28% in the placebo group (ns). The cumulative risk for a first attack of pouchitis was 30% and 26% after 24 months (ns). The overall pouch function improved over time and did not differ significantly between the two groups. CONCLUSIONS: Prophylactic Allopurinol did not reduce the risk of a first attack of pouchitis.

Adolescent↗
PubMed1999

Fertility after ileal pouch-anal anastomosis in women with ulcerative colitis.

BACKGROUND: Women with ulcerative colitis are believed to have normal fertility but colectomy and ileal pouch-anal anastomosis (IPAA) may impair fertility. The aim was to compare fertility in patients with ulcerative colitis before and after IPAA with that in the national population. METHODS: Some 258 consecutive women who had undergone IPAA for ulcerative colitis were identified. Data were collected by questionnaire and from medical records. The observed number of births was compared with the number expected by indirect standardization by age and calendar year. Fertility from the age of 15 years to colectomy, from the onset of ulcerative colitis to colectomy, and from the 12 months after stoma closure to the time of data collection was investigated. RESULTS: A total of 237 women (92 per cent) responded. From the age of 15 years to colectomy there were 251 deliveries compared with an expected number of 286 (P < 0. 05). The number of births from the onset of ulcerative colitis to colectomy was 120, compared with an expected 131 (P > 0.3). From the 12 months after ileostomy closure until data collection there were 34 deliveries, compared with an expected 69 (P < 0.001). CONCLUSION: There is a considerable reduction in postoperative fertility after restorative surgery for ulcerative colitis.

Adult↗
PubMed1994

Effect of some poly(ethylene glycol)-bound and dextran-bound affinity ligands on the partition of synaptic membranes in aqueous two-phase systems.

Ligands with an apparent affinity for various structural elements on the surface of synaptic membrane fragments have been bound to the polymers poly(ethylene glycol) and dextran. The ligand-polymer derivatives have been included in aqueous two-phase systems composed of water, poly(ethylene glycol) and dextran. The uneven distribution of the polymers resulted in the concentration of the polymer-bound ligand in one of the two phases. The effect of the ligand-polymer on the partition of membranes was studied by using synaptic membranes from calf brain, obtained by standard centrifugation methods. By using ligand-containing two-phase systems for nine-step counter-current distribution of membranes, it was shown that the distribution behaviour of various parts of the membrane preparation could be affected. The distribution was followed by determination of opiate binding, acetylcholinesterase, and total membrane (using protein and light-scattering measurements).

Acetylcholinesterase↗
PubMed1994

Structural organization of reconstituted human arterial smooth muscle tissue.

We used human arterial smooth muscle cells (SMCs) that had been reorganized three-dimensionally into aggregates, so-called spheroids, as a model system that might more closely correspond to arterial smooth muscle in vivo than do conventional monolayer cultures. After reaggregation the presence of serum in the culture medium strongly promoted the maintenance of spheroidal SMCs. With access to fresh serum, the spheroids developed into highly organized structures with an outer laminated shell of spindle-shaped SMCs and a more porous core of rounded or polygonal SMCs. After several weeks in culture, extracellular matrix components appeared and the tissue assumed features characteristic of maturing intimal repair tissue. Many cells had features of programmed cell death (apoptosis). This feature may be important because it may indicate that regression of arterial smooth muscle tissue may be a much more strongly controlled process than hitherto realized. Without access to fresh serum, the spheroidal tissue showed degenerative features, much like those in atherosclerotic lesions, ie, the presence of foam cells, cellular debris, and some cell death. It is possible that this situation in vitro resembles that of atherosclerotic tissue in vivo, in which retention of plasma constituents is a conspicuous feature. In some respects, therefore, the small sample of human arterial tissue represented by the spheroid may represent an in vitro analogue of the arterial wall, which may undergo maturation or degenerative atherosclerosis-like changes depending on exogenous factors. The spheroidal SMC system may therefore also be a suitable model for in vitro studies of atherogenesis.

Aorta, Abdominal↗
PubMed1990

Partition of synaptic membranes in aqueous two-phase systems at subzero temperatures by using anti-freeze solvent.

The freezing point of aqueous two-phase (liquid-liquid) systems containing water, dextran and poly(ethylene glycol) has been lowered by including glycerol. Biological membranes, obtained by fragmentation of a crude synaptosomal preparation from calf brain cortex, have been included in the two-phase systems. The effects of temperature and the concentration of glycerol on the partition of the membranes within the systems have been investigated. Considerable stabilisation of the membranes was noticed when they were partitioned at -10 degrees C compared with 0 degrees C. The influences of glycerol, ethylene glycol, N,N-dimethylformamide and tetrahydrofuran on the phase-forming properties of the systems and on enzyme activities are also presented. Possible use of the above systems for studies and separation of biological membranes are discussed.

Animals↗
PubMed1987

Effect of polymer structure on affinity partitioning of lactate dehydrogenase in polymer-water two-phase systems.

Lactate dehydrogenase from rabbit muscle (EC 1.1.1.27) was partitioned between the liquid phases of aqueous two-phase systems containing two kinds of polymers. The partition was influenced by the use of a dye ligand, Procion Yellow HE-3G, bound to a polymer. The ligand-carrying polymers were poly(ethyleneglycol), poly(vinyl alcohol), ethylhydroxyethylcellulose, hydroxypropyl-starch, Ficoll and dextran. Their influence on the partition of lactate dehydrogenase was studied in systems composed of the following pairs of polymers: dextran-poly(ethylene glycol), dextran-poly(vinyl alcohol), dextran-Ficoll and hydroxypropyl-starch-poly (ethylene glycol). The ratio between the change in the logarithmic partition coefficient of the enzyme, delta log K, caused by the ligand and the logarithm of the partition coefficient of the ligand-polymer, log KL-polymer, was used as a measure of the number of ligand polymers bound per enzyme molecule under saturation conditions. Possible explanations for the observed effects are discussed.

Animals↗
PubMed1987

Affinity partitioning of enzymes using dextran-bound procion yellow HE-3G. Influence of dye-ligand density.

The dye Procion Yellow HE-3G was bound to dextran of molecular weight 70,000 and the partitioning of this dye-polymer within an aqueous two-phase system containing dextran and poly(ethylene glycol) was studied as function of ligand density, polymer concentration, type of salt, concentration of salt and concentration of dye-dextran. Even moderate dye:dextran molar ratios (5-8) make the partitioning strongly salt-dependent. The dye-dextran can be directed to either the upper or the lower phase with partition coefficients from 0.02 to 28 by using salts. The dye-dextran in the two-phase system affects the partitioning of dye-binding enzymes (lactate dehydrogenase, glucose-6-phosphate dehydrogenase, 3-phosphoglycerate kinase) towards the dye-containing phase. Measurements of competition with nucleotide binding show an increased affinity of the dye for the enzyme with increasing ligand:dextran ratio. Theoretical considerations indicate that 1-2 dextran molecules are attached per enzyme molecule when affinity partitioning is fully developed.

Chromatography, Affinity↗
PubMed1986

Liquid-liquid extraction of lactate dehydrogenase from muscle using polymer-bound triazine dyes.

An extract from porcine muscle containing soluble enzymes has been partitioned between the two liquid phases of an aqueous, biphasic system consisting of dextran, polyethylene glycol, and water. The influence of polymer-bound triazine dyes (Cibacron blue F3G-A and Procion yellow HE-3G) on the partition of lactate dehydrogenase and total protein was studied. The effects of pH and concentrations of polymers and buffer on this so-called affinity partitioning were also determined. The two-phase systems were used in extraction procedures for purification of lactate dehydrogenase to a specific activity of 456-494 U (7.6-8.4 mukat) per mg protein. The use of these systems for extraction of enzymes in technical scale is discussed.

Animals↗
PubMed1986

Specifically increased solubility of enzymes in polyethyleneglycol solutions using polymer-bound triazine dyes.

The enzymes glucose-6-phosphate dehydrogenase (EC 1.1.1.49) and 3-phosphoglycerate kinase (EC 2.7.2.3), present in an extract of Bakers' yeast, are largely kept in solution by minor amounts of polyethylene glycol-bound triazine dyes (Procion yellow HE-3G and Procion olive MX-3G) even when the solution contains such concentrations of polyethylene glycol (12.5% w/w) which normally precipitate the enzymes. The specific prevention from precipitation can be used for purification of enzyme, preferentially in dealing with crude extracts, which has been demonstrated in this work. A 3.4-fold purification of glucose-6-phosphate dehydrogenase has been achieved with good recovery (93%). Further purification has been possible by combining the recovered (enzyme-containing) supernatant liquid with a solution of dextran which generates an aqueous two-phase system. The lower, dextran-containing phase extracts part of the remaining bulk proteins leaving the target enzyme in the upper phase. The advantages of this method for enzyme purification in large scale are discussed.

Coloring Agents↗