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| 2. |
- Herlitz, Johan, et al.
(författare)
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Physical activity, symptoms of chest pain and dyspnea in patients with ischemic heart disease in relation to age before and two years after coronary artery bypass grafting
- 2001
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Ingår i: Journal of Cardiovascular Surgery. - : Edizioni Minerva Medica. - 0021-9509 .- 1827-191X. ; 42:2, s. 165-173
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: To describe limitation of physical activity, cause of limitation of physical activity and symptoms of dyspnea and chest pain in relation to age before and 2 years after coronary artery bypass grafting (CABG). METHODS: All patients from Western Sweden who underwent CABG without concomitant procedures during 3 years in 1989-1991 answered questionnaires before, and 2 years after the operation. Patients were divided into 3 age groups of equal size i.e. 32-59 years, 60-67 years and > or = 68 years. RESULTS: In total, 2121 patients participated in the evaluation. The overall 2 year mortality in the 3 age groups was 3.8%, 6.8% and 12.2% (p<0.001). Limitation of physical activity was significantly associated with age prior to surgery but not thereafter. Improvement in physical activity, following CABG, was significant in all age groups. The proportion of patients being free of dyspnea increased markedly regardless of age. The number of chest pain attacks was associated with age after CABG, i.e. fewer attacks in the elderly, but such an association was not found prior to surgery. Improvement in number of chest pain attacks was more marked in the elderly. CONCLUSIONS: Physical activity improved similarly in all age groups after CABG. Attacks of chest pain, although significantly reduced in all age groups, seemed more effectively reduced in the elderly.
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| 3. |
- Ranucci, E., et al.
(författare)
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New ester and lactone end-functionalized N-vinyl-2-pyrrolidinone oligomers
- 2000
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Ingår i: Macromolecular Chemistry and Physics. - 1022-1352 .- 1521-3935. ; 201:12, s. 1219-1225
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Tidskriftsartikel (refereegranskat)abstract
- New oligomers of N-vinyl-2-pyrrolidinone functionalized at one end with either ester or lactone functions were obtained by radical polymerization in the presence of different ester (methyl isobutyrate and methyl phenylacetate) and lactone (epsilon-caprolactone, delta-valerolactone and gamma-btyrolactone) compounds as chain transfer agents. The oligomeric samples obtained were characterized in terms of molecular weight and molecular weight distribution by means of analytical size exclusion chromatography (SEC), using purposely synthesized poly(N-vinyl-2-pyrrolidinone) standards. The chain transfer constant C-tau of either methyl isobutyrate, delta-valerolactone, or gamma-butyrolactone towards N-vinyl-2-pyrrolidinone were determined with the help of the known cumulative number-average degree of polymerization (X) over bar(n) and monomer conversion Y-t of the samples during the reaction.
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| 4. |
- Ryner, M., et al.
(författare)
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Mechanism of ring-opening polymerization of 1,5-dioxepan-2-one and L-lactide with stannous 2-ethylhexanoate. A theoretical study
- 2001
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Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 34:12, s. 3877-3881
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Tidskriftsartikel (refereegranskat)abstract
- A theoretical study of the ring-opening polymerization (ROP) mechanism of 1,5-dioxepana-2-one (DXO) and (L)-lactide (LLA) with stannous(IE) a-ethylhexanoate (Sn(Oct)(2)) is presented. The B3LYP density functional method has been used for the quantum chemical calculations. Our results support a coordination-insertion mechanism initiated by a tin-alkoxide species formed prior to the ROP. The rate-determining step in the ROP was the nucleophilic attack of the alkoxide on the carbonyl carbon of the monomer. The activation energy for the ROP of DXO with Sn(Oct ')(2) has been determined to be 19.8 kcal/mol and for L-lactide 20.6 kcal/mol. At normal reaction temperatures, a ligand may dissociate as Oct 'H during propagation. An excess of carboxylic acid hinders the coordination of monomer to the initiating/propagating complex.
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| 5. |
- von Schenck, H., et al.
(författare)
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Ring-opening polymerization of lactones and lactides with Sn(IV) and Al(III) initiators
- 2002
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Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 35:5, s. 1556-1562
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Tidskriftsartikel (refereegranskat)abstract
- A theoretical study is presented of the ring-opening polymerization (ROP) mechanism of 1,5-dioxepan-2-one (DXO) and glycolide with Sn(II) and Al(III) alkoxide initiators (SnMe3MeO, SnMe2-(MeO)(2), and AlMe2MeO). The B3LYP density functional method has been used to perform the quantum chemical calculations. A coordination-insertion mechanism is presented with two principal reaction steps. First, the alkoxide of the initiator performs a nucleophilic attack on the carbonyl carbon, and the carbonyl bond is broken. An intermediate is formed at this point, where the former carbonyl oxygen of the monomer is coordinated to tin via an alkoxide bond, while the carbonyl carbon assumes a sp(3) bonding geometry. The second step involves the acyl-oxygen cleavage of the monomer. For all three initiators it was found that the transition state involving the breaking of the carbonyl double bond (TS1) represented the highest point on the potential energy surface for DXO. For glycolide, however, the transition state of the acyl-oxygen cleavage (TS2) was the least stable structure. The reaction barriers were calculated to 17.1 kcal/mol for DXO/SnMe3MeO, 18.7 kcal/mol for glycolide/SnMe3MeO, 14.3 kcal/mol for DXO/SnMe2(MeO)(2), 14.5 kcal/mol for glycolide/SnMe2(MeO)(2), 13.6 kcal/mol for DXO/AlMe2MeO, and 9.3 kcal/mol for glycolide/AlMe2MeO. Both electronic and steric properties of the monomer affect the reaction barriers. It was found that the more electrophilic initiators polymerized cyclic esters faster.
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| 6. |
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| 7. |
- Bjarnason, Ragnar, 1959, et al.
(författare)
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Cartilage oligomeric matrix protein increases in serum after the start of growth hormone treatment in prepubertal children
- 2004
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 89:10, s. 5156-60
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Tidskriftsartikel (refereegranskat)abstract
- Both GH and IGF-I stimulate bone growth, but the molecular mechanisms mediating their effects on the growth plate are not fully understood. We measured gene expression by microarray analysis in primary cultured human chondrocytes treated with either GH or IGF-I. One of the genes found to be up-regulated by both GH and IGF-I was that encoding cartilage oligomeric matrix protein (COMP). This protein is predominantly found in the extracellular matrix of cartilage. Mutations in the COMP gene have been associated with syndromes of short stature. To verify that COMP is regulated by GH in vivo, we measured COMP levels in serum in short children treated with GH. The study included 113 short prepubertal children (14 girls and 99 boys) with a mean (+/- sd) age of 8.84 +/- 2.76 yr, height sd score of -2.74 +/- 0.67, and IGF-I sd score of -1.21 +/- 1.07 at the start of GH administration. Serum levels of COMP were 1.58 +/- 0.28, 1.83 +/- 0.28 (P < 0.0001), 1.91 +/- 0.28 (P < 0.0001), 1.78 +/- 0.28 (P < 0.001), and 1.70 +/- 0.24 (P < 0.05) microg/ml at baseline and after 1 wk and 1, 3, and 12 months, respectively.In conclusion, we have demonstrated that COMP expression is up-regulated by both GH and IGF-I in primary cultured human chondrocytes. Furthermore, serum levels of COMP increase after the start of GH treatment in short children.
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| 8. |
- Blair, J. C., et al.
(författare)
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Standard and low-dose IGF-I generation tests and spontaneous growth hormone secretion in children with idiopathic short stature
- 2004
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Ingår i: Clin Endocrinol (Oxf). ; 60:2, s. 163-8
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Abnormalities in the GH-IGF-I axis, consistent with GH insensitivity (GHI), have been reported in some patients with idiopathic short stature (ISS). The standard IGF-I generation test (IGFGT) has not demonstrated mild GHI in subjects with ISS. The aim of this study was to investigate the GH-IGF-I axis in ISS by performing standard and novel low-dose IGFGTs together with determination of spontaneous GH secretion. PATIENTS AND METHODS: Twenty-one (17 male) prepubertal children with ISS, mean age 8.3 years (4.5-12.2), mean height -3.48 SD (-5.40 to -1.79), mean peak GH to provocation with glucagon/clonidine 32.3 mU/l (14.1-66.0) were studied. Serum IGF-I and IGFBP-3 levels were measured during standard (GH 0.033 mg/kg/day x 4) and low (GH 0.011 mg/kg/day x 4) dose IGFGTs at 0, 12, 36 and 84 h. The low-dose IGFGT was performed in seven naive GH-deficient patients (4 male), mean age 8.5 years (range 4.1-11.1). Determination of spontaneous 24-h GH secretion was performed in the 21 ISS patients. RESULTS: Basal IGF-I and IGFBP-3 standard deviation scores (SDS) in ISS patients were -1.39 (-2.4-1.16) and -0.45 (-1.13-0.38), respectively, IGF-I being lower than IGFBP-3 (P < 0.0001). IGF-I increased in the standard IGFGT at 12 h (P < 0.005), 36 h (P < 0.001) and 84 h (P < 0.001); maximal increment 1.54 (-0.32-3.48), and in the low-dose test at 12 h (P < 0.005), 36 h (P < 0.001) and 84 h (P < 0.005); maximal increment 0.53 (0.08 to -1.23). IGFBP-3 SDS increased in the standard IGFGT at 36 h (P < 0.01) and 84 h (P < 0.001); maximal increment 0.72 (-0.44-1.96), and in the low-dose test at 84 h (P < 0.005); maximal increment 0.33 (-0.08-0.87). Five/19 patients with an IGF-I response > 2 x coefficient of variation (CV) of assay in the standard test failed to respond in the low-dose test, suggestive of mild GHI. In GH-deficient patients, IGF-I increased at each time point (P < 0.05) and IGFBP-3 at 36 h (P < 0.05). Mean GH secretion, expressed in SDS, compared with 66 normal stature controls was: basal GH -0.48 (-0.84-0.93), height of GH peaks compared with zero -0.36 (-1.26-1.51) (both P < 0.05), total GH secretion -0.76 (-1.22-0.42), total GH secretion above baseline -0.67 (-1.21-0.94) (both P < 0.01). CONCLUSIONS: In children with ISS, basal IGF-I and IGFBP-3 SDS values were below the mean, IGF-I showing a greater response in both IGFGTs. In the standard IGFGT, the IGF-I increase at 36 h was equal to that at 84 h. The low-dose IGFGT, in combination with the standard test, may identify patients with mild GHI.
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| 9. |
- Finne Wistrand, Anna, et al.
(författare)
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Degradable polymers : Design, synthesis and testing
- 2003
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Ingår i: Macromolecular Symposia. - : Wiley. - 1022-1360 .- 1521-3900. ; 195, s. 241-246
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Tidskriftsartikel (refereegranskat)abstract
- The object for our research is to mimic Nature's perfectly designed resorbable materials to obtain important materials, which are biocompatible and degradable. We have therefore synthesized different architectures and copolymers of aliphatic polyesters with ring-opening polymerization. The first studies of these materials properties show that properties like hydrophilicity and tensile properties can be controlled.
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| 10. |
- Hakkarainen, Minna, et al.
(författare)
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Solid-phase microextraction (SPME) in polymer characterization - Long-term properties and quality control of polymeric materials
- 2003
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Ingår i: Journal of Applied Polymer Science. - : Wiley. - 0021-8995 .- 1097-4628. ; 89:3, s. 867-873
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Tidskriftsartikel (refereegranskat)abstract
- Solid-phase microextraction (SPME) in combination with GG-MS was applied to quality control polyamide 6.6 collected for recycling and to study the long-term properties and degadation of nitrile rubber, polyethylene, and polyamide 6.6. The migration of plasticizer and other additives reduces the service-life and changes the properties of the material. It is also a possible health hazard, for example, legislation against the use of brominated flame retardants in plastic materials, is under discussion, and fast and reliable methods are required to detect such compounds in plastic materials collected for recycling. SPME rapidly and effectively extracted several brominated compounds from in-plant collected polyamide 6.6. Migration of tris(2-butoxy-ethyl)phosphate plasticizer and its degradation products from nitrile rubber during long-term thermal ageing at 60 and 80degreesC was shown by SPME-GC-MS, while the plasticizer was not volatile enough to be detected by traditional HS-GC-MS. In accordance the number of degradation products extracted from thermo-oxidized PE by HS-SPME was three times larger than the number detected after HS-GC-MS analysis. SPME-GC-MS could also detect early signs of degradation in thermo-oxidized virgin and in-plant recycled polyamide 6.6 before any signs of degradation were observed by, for example, tensile testing or FTIR.
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