| 1. |
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Hammarstrom, L, et al.
(författare)
-
Mimicking photosystem II reactions in artificial photosynthesis
- 1999
-
Ingår i: ZEITSCHRIFT FUR PHYSIKALISCHE CHEMIE-INTERNATIONAL JOURNAL OF RESEARCH IN PHYSICAL CHEMISTRY & CHEMICAL PHYSICS. - : R OLDENBOURG VERLAG. - 0942-9352. ; 213, s. 157-163
-
Tidskriftsartikel (refereegranskat)abstract
- The paper describes a project aiming at the construction of functional mimics of the oxygen evolving complex of Photosystem II, coupled to photoinduced charge separation. Biomimetic electron donors - manganese complexes and tyrosine - have been linked to
|
|
| 5. |
- Hammarström, Leif, et al.
(författare)
-
Mimicking Photosystem II Reactions in Artificial Photosynthesis
- 1999
-
Ingår i: Zeitschrift für Physikalische Chemie. - 0942-9352. ; 213:2, s. 157-163
-
Tidskriftsartikel (refereegranskat)abstract
- The paper describes a project aiming at the construction of functional mimics of the oxygen evolving complex of Photosystem II, coupled to photoinduced charge separation. Biomimetic electron donors - manganese complexes and tyrosine - have been linked to a Ru(II)-polypyridine photosensitizer. Oxidation of the donors by intramolecular electron transfer from the photo-oxidized Ru(III) complex was demonstrated using optical flash photolysis and EPR experiments. A step-wise electron transfer Mn → tyrosine → Ru(III) was demonstrated, in a sequence analogous to reactions of the PSII donor side.
|
|
| 6. |
- Hou, Mingyan, et al.
(författare)
-
Increase in cardiac P2X1-and P2Y2-receptor mRNA levels in congestive heart failure
- 1999
-
Ingår i: Life Sciences. - 1879-0631. ; 65:11, s. 1195-1206
-
Tidskriftsartikel (refereegranskat)abstract
- We wanted to study the expression of P2-receptors at the mRNA-level in the heart and if it is affected by congestive heart failure (CHF). To quantify the P2 receptor mRNA-expression we used a competitive RT-PCR protocol which is based on an internal RNA standard. The P2 receptor mRNA-expression was quantified in hearts from CHF rats and compared to sham-operated rats. Furthermore, the presence of receptor mRNA was studied in the myocardium from patients with heart failure. In the sham operated rats the G-protein coupled P2Y-receptors were expressed at a higher level than the ligand gated ion-channel receptor (P2X1). Among the P2Y-receptors the P2Y6-receptor was most abundantly expressed (P2Y6 > P2Y1 > P2Y2 = P2Y4 > P2X1). A prominent change was seen for the P2X1- and P2Y2-receptor mRNA levels which were increased 2.7-fold and 4.7-fold respectively in the myocardium from the left ventricle of CHF-rats. In contrast, the P2Y1-, P2Y4- and P2Y6-receptor mRNA levels were not significantly altered in CHF rats. In human myocard the P2X1-, P2Y1-, P2Y2-, P2Y6- and P2Y11-receptors were detected by RT-PCR in both right and left atria and ventricles, while the P2Y4-receptor band was weak or absent. In conclusion, most of the studied P2-receptors were expressed in both rat and human hearts. Furthermore, the P2X1- and P2Y2-receptor mRNA were upregulated in CHF, suggesting a pathophysiological role for these receptors in the development of heart failure.
|
|
| 7. |
- Huang, QW, et al.
(författare)
-
Effects of inhaled nitric oxide and high-frequency ventilation in rabbits with meconium aspiration
- 1999
-
Ingår i: Biology of the neonate. - : S. Karger AG. - 0006-3126. ; 76:6, s. 374-382
-
Tidskriftsartikel (refereegranskat)abstract
- Aim: To evaluate effects of inhaled nitric oxide (iNO) in experimental meconium aspiration treated with high-frequency (HFV) or conventional mechanical ventilation (CMV). Ventilated adult rabbits had meconium instilled intratracheally resulting in respiratory failure as evidenced by more than 50% reduction of dynamic lung compliance (Cdyn) and increase in mean oxygenation index (OI) from 1 to 16. The animals were then allocated to 2 groups treated without (control) or with iNO at 20 ppm (NO). In each group the animals were initially ventilated with CMV or HFV mode for 3 h and then in a crossover fashion with HFV or CMV for another 3 h (CMV→HFV, HFV→CMV), respectively. In the first 3 h of treatment, the animals subjected to HFV-CMV in the control, and those with both HFV-CMV and CMV-HFV in the NO group had significantly reduced OI. In the subsequent 3 h, the animals in the control group with CMV-HFV did not improve in OI and those with HFV-CMV had deteriorated. In the NO group with both CMV-HFV and HFV-CMV moderate improvement of OI was observed. Platelet aggregation capability and counts were significantly decreased and bleeding time prolonged in animals receiving iNO treatment. These results suggest that both HFV alone and a combined treatment of iNO with either CMV or HFV are more effective in improving blood oxygenation than that of CMV in this animal model. The influence of iNO on platelet aggregation should be considered.
|
|
| 8. |
- Malmsjö, Malin, et al.
(författare)
-
Congestive heart failure induces downregulation of P2X1-receptors in resistance arteries
- 1999
-
Ingår i: Cardiovascular Research. - 1755-3245. ; 43:1, s. 219-227
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Congestive heart failure (CHF) is accompanied by enhanced peripheral sympathetic nerve activity, increased vascular resistance and impaired peripheral blood flow. Besides noradrenaline and neuropeptide Y, the sympathetic nervous system also releases ATP, which has contractile effects mediated by different subtypes of P2-receptors on the vascular smooth muscle cells. The present study was designed to examine postsynaptic changes of the contractile responses to ATP and other extracellular nucleotides in CHF. METHODS: CHF was induced by left coronary artery ligation resulting in a reproducible myocardial infarction in Sprague-Dawley rats. Contractile responses were examined in cylindrical segments of aorta and the mesenteric artery after endothelium removal. To determine if an altered response was regulated on the transcriptional level, competitive reverse transcription polymerase chain reaction (RT-PCR) was used to estimate the amount of P2X1-receptor mRNA. RESULTS: ATP, which is both a P2X1- and a P2Y-receptor agonist, induced a weaker contraction in the mesenteric artery from CHF as compared to sham operated rats. A decrease in both potency and maximum contraction was shown for the selective P2X1-receptor agonist, alpha beta-MeATP, in the mesenteric artery (pEC50 = 6.04 vs. 5.76, Cmax = 57% vs. 33%, sham vs. CHF operated rats), but not in the aorta. Competitive RT-PCR also revealed decreased P2X1-receptor mRNA levels in CHF operated rats in the mesenteric artery (9106 x 10(3) vs. 714 x 10(3) molecules/microgram, sham vs. CHF operated rats), while it remained unaltered in the aorta. To study the P2Y-receptor induced contractile effects, the P2X1-receptors were first desensitised with alpha beta-MeATP (10(-5) M for 8 min). After P2X1-receptors desensitisation, UTP and UDP induced strong contractions in both the mesenteric artery and in the aorta, while ATP and ADP were much less effective. These contractions were not altered by CHF, indicating that vascular contraction mediated by P2Y-receptors are unaffected by CHF. CONCLUSION: CHF induces downregulation of P2X1-receptor stimulated contraction in the mesenteric artery depending on decreased mRNA synthesis for the receptor, while the P2Y-receptor activity remains unchanged. Downregulation of P2X1-receptors appears to be specific for peripheral resistance arteries. This may represent a compensatory response to enhanced peripheral sympathetic nerve activity and increased vascular resistance in CHF.
|
|
| 9. |
- Malmsjö, Malin, et al.
(författare)
-
Enhanced acetylcholine and P2Y-receptor stimulated vascular EDHF-dilatation in congestive heart failure
- 1999
-
Ingår i: Cardiovascular Research. - 1755-3245. ; 43:1, s. 200-209
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Congestive heart failure (CHF) is accompanied by impaired peripheral blood flow and endothelial dysfunction with decreased release of nitric oxide (NO). Strong evidence supports the existence of another vasodilatory substance, endothelium derived hyperpolarising factor (EDHF), which has not previously been studied in CHF. METHOD: CHF was induced by left coronary artery ligation resulting in a reproducible myocardial infarction in Sprague Dawley rats. Vasodilatory responses to acetylcholine and extracellular nucleotides (ATP, ADP beta S, ADP and UTP) were examined in cylindrical segments of the mesenteric artery, precontracted with noradrenaline. The combined NO- and EDHF-dilatation (after inhibition of cyclo-oxygenase pathways) was called "total dilatation", as indomethacin had only minor effects in this system. NO-dilatation was studied in segments pretreated with indomethacin and the potassium channel inhibitors charybdotoxin (10(-7.5) M) and apamin (10(-6) M), while EDHF-dilatations were studied in the presence of indomethacin (10(-5) M) and L-NOARG (10(-3.5) M). RESULTS: EDHF-dilatations in CHF were strongly up-regulated for ACh (36% vs. 73%; sham vs. CHF operated rats), ADP beta S (10% vs. 42%), ADP (0% vs. 21%) and UTP (3% vs. 35%). These dilatations were abolished by a combination of charybdotoxin and apamin, confirming that they were mediated by EDHF. The NO-dilatations on the other hand were down-regulated in CHF as compared to sham operated rats for ACh (93% vs. 76%; sham vs. CHF operated rats), ADP beta S (61% vs. 37%). ADP (60% vs. 30%), ATP (49% vs. 34%) and UTP (65% vs. 47%), while a minor decrease was seen in the total dilatation for ACh (87% vs. 75%; sham vs. CHF operated rats), ADP beta S (47% vs. 42%), ADP (59% vs. 39%), ATP (52% vs. 39%) and UTP (59% vs. 44%). CONCLUSION: In this model of non-atherosclerotic CHF there was a minor decrease in the total dilatation and a marked down-regulation of the NO-mediated dilatation, while the EDHF-dilatation was up-regulated. Increased EDHF-activity in CHF may represent a compensatory response to decreased NO-activity to preserve endothelial function and tissue perfusion.
|
|
| 10. |
- Rao, Q.H., et al.
(författare)
-
Mode II fracture toughness testing of rock
- 1999
-
Ingår i: Comptes-rendus / 9 Congrès international de mécanique de roches, Paris, France 1999. - Rotterdam : Balkema Publishers, A.A. / Taylor & Francis The Netherlands. - 905809071X ; , s. 731-734
-
Konferensbidrag (refereegranskat)
|
|
