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- Albinsson, Bo, 1963, et al.
(författare)
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The origin of lignin fluorescence
- 1999
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Ingår i: Journal of Molecular Structure. - 0022-2860. ; 508:1-3, s. 19-27
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Tidskriftsartikel (refereegranskat)abstract
- Spruce lignin exhibits fluorescence emission spectra that peaks at approximate to 360 nm on excitation at wavelengths ranging from 240 to 320 nm. This can be explained by non-radiative energy transfer from lignin chromophores, that are excited in the wavelength range 240-320 nm, to an acceptor that emits fluorescent Light at approximate to 360 nm. Examinations of lignin samples and model compounds suggest that small amounts of phenylcoumarone structures in the lignin is a conceivable acceptor. Such structures and stilbene structures are formed from structural elements in lignin of the phenylcoumaran type on various treatments. The photophysical properties of models for phenylcoumarone structures [2-(3,4-dimethoxyphenyl)-7-methoxy-3-methyo[b]-furan, 2-(3,4-dimethoxyphenyl)-3-hydroxymethyl-7-methoxybenzo[b]furan] and stilbene structures (the E and Z forms of 2-hydroxy-3,3',4'-trimethoxystilbene) have been examined and are discussed on the basis of crystal structure determinations. (C) 1999 Elsevier Science B.V. All rights reserved.
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| 3. |
- Fan, Bo-Guang, et al.
(författare)
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Total parenteral nutrition influences both endocrine and exocrine function of rat pancreas
- 1997
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Ingår i: Pancreas. - 0885-3177. ; 15:2, s. 147-153
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to examine the effect of total parenteral nutrition (TPN) on the endocrine and exocine function of the pancreas. Endocrine function was investigated using an intravenous glucose tolerance test (IGTT) in rats with TPN for 7 or 14 days. Exocrine function was evaluated by measuring amylase secretion from isolated acini as well as pancreatic weight, water content, protein, and enzymes after 7 days of TPN. When the TPN rats were compared with the controls, the glucose tolerance curve after an IGTT was unchanged, the basal plasma insulin levels were slightly lower and the insulin secretory response to intravenous glucose was markedly impaired. No differences could be seen between the insulin response after 7 days and that after 14 days of TPN. The weight of pancreas, the total content and concentration of pancreatic protein, and the total amylase content of the pancreas were lower, whereas the total content of both chymotrypsin and trypsin was higher. The concentration of DNA remained intact, whereas the total DNA content decreased. The levels of lipolytic enzymes, except for carboxylesterlipase, were unaffected. After TPN treatment, the insulin secretory response to glucose is impaired, the exocrine pancreas is hypoplastic and the storage pattern of pancreatic exocrine enzymes is altered.
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| 5. |
- Hårsta, Anders, et al.
(författare)
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In situ halide chemical vapor deposition of Bi2Sr2CaCu2O8+x on silver substrates
- 1996
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Ingår i: Chemical Vapor Deposition. - VCH Publishers Inc. ; 2, s. 3109-112
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The superconducting Bi2Sr2CaCu2O8+x phase is deposited on polycrystalline silver substrates by halide CVD in the temperature interval 760-820 degrees C. Metal iodides and oxygen are used as precursor materials. The films grow with a pronounced [001] orie
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| 8. |
- Lundquist, Ingmar, et al.
(författare)
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Islet acid glucan-1,4-alpha-glucosidase: a putative key enzyme in nutrient-stimulated insulin secretion
- 1996
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Ingår i: Endocrinology. - 0013-7227. ; 137:4, s. 1219-1225
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Tidskriftsartikel (refereegranskat)abstract
- Little attention has been paid to a possible relationship between lysosomal function and stimulation of secretory processes in endocrine cells. The last few years it has become increasingly evident that the secretion of insulin from the pancreatic beta-cell is the result of a very complex cascade of events, the details of which are far from elucidated and indeed may include the participation of the lysosomal system. We report here, with a combined in vitro and in vivo approach, that selective inhibition of islet lysosomal glycogenolytic acid glucan-1,4-alpha-glucosidase activity by the long-acting 1-deoxynojirimycin derivative emiglitate induces a profound suppression of nutrient-induced insulin release. In islet homogenate emiglitate strongly and dose-dependently inhibited the activity of acid glucan-1,4-alpha-glucosidase (EC50 approximately 10(-6) M) without affecting other classical lysosomal enzyme activities. The emiglitate-induced inhibition curve for glucose-stimulated insulin secretion from isolated islets was remarkably similar to the inhibition curve for acid glucan-1,4-alpha-glucosidase. Moreover, insulin release stimulated by the nonglucose nutrient secretagogues, leucine, and alpha-ketoisocaproic acid (KIC) was totally suppressed by emiglitate. In contrast, receptor activated insulin secretion induced by the insulinotropic hormone cholecystokinin (CCK-8) was unaffected by the drug. Further, parenteral pretreatment of mice with emiglitate markedly suppressed the insulin secretory response to an iv injection of glucose or KIC, whereas the response to an iv injection of CCK-8 was unaffected. In accordance with this, islets isolated from emiglitate-treated mice showed a reduced activity of acid glucan-1,4-alpha-glucosidase and, moreover, such islets incubated in vitro, secreted less insulin in response to glucose than did control islets. Finally, pretreatment of mice with purified fungal acid glucan-1,4-alpha-glucosidase, enzyme replacement, brought about a markedly increased insulin secretory response after an iv injection of KIC, whereas the insulin response after CCK-8 injection was unaffected. Taken together with previous observations, the present data strongly suggest that islet lysosomal acid alpha-glucosidehydrolases are involved in the multifactorial process of nutrient-induced insulin secretion. The existence of hitherto unresolved and complex interactions between different beta-cell organelles in the insulin secretory processes should be thoroughly reevaluated.
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| 9. |
- Moberg, K, et al.
(författare)
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Two models for radiological reviewing of interval cancers
- 1999
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Ingår i: Journal of medical screening. - : SAGE Publications. - 0969-1413 .- 1475-5793. ; 6:1, s. 35-39
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Tidskriftsartikel (refereegranskat)abstract
- Objectives To compare two different review methods of examining how many of our interval cancers could be regarded as missed cases (overlooked and misinterpreted owing to observer's error). Setting A mass screening programme in Stockholm 1989–91, performed at five independent screening units. 107 846 women attended for screening (70.6% of those invited), and 207 women with interval breast cancers were identified. Interval cancers from two of the units, 104 cases, are reviewed in this study. Methods Screening examinations preceding the interval cancer diagnoses were reviewed both mixed with other screening images in a ratio 1:8 and non-mixed. Both internal reviewers (from the two units responsible for the screening mammograms) and external reviewers (from the other units) took part in the study. Results The proportion regarded as missed cases varied between 7% and 34%, depending on what review method was used, and on the number of reviewers included to identify a case as missed. Mixed reviewing reduced the number identified as missed cases by 50% compared with non-mixed reviewing. Whether the reviewer was internal or external made no difference to the results. Conclusions Comparing the rate of missed cases from different studies may be misleading unless the same review method is used. No difference in detection rate could be shown whether the radiologist reviewed images from his/her own screening unit or not. Most of our interval cancers were not regarded as missed cases by either of the two methods.
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| 10. |
- Monstein, H J, et al.
(författare)
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Cholecystokinin-A and cholecystokinin-B/gastrin receptor mRNA expression in the gastrointestinal tract and pancreas of the rat and man. A polymerase chain reaction study
- 1996
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Ingår i: Scandinavian Journal of Gastroenterology. - : Informa UK Limited. - 1502-7708 .- 0036-5521. ; 31:4, s. 383-390
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Gastrin and cholecystokinin (CCK) are thought to exert trophic effects on the gastrointestinal tract and pancreas. Two types of receptors have been cloned, CCK-A and CCK-B/ gastrin. We have examined the occurrence of CCK-A and CCK-B receptor mRNA in the brain, digestive tract, pancreas, and kidney of the rat and man by Northern blot and reverse transcribed polymerase chain reaction (RT-PCR). METHODS: Total RNA was isolated from rat tissues and reverse transcribed into cDNA. cDNA from brain, kidney, and pancreas of the rat and man and from human whole stomach were commercially available. Northern blot and a PCR technique based on Taq polymerase-antibody interaction and using CCK-A and CCK-B receptor-specific primers, followed by Southern blot analysis, were the methods used. RESULTS: By means of Northern blots, CCK-A receptor mRNA was detected in rat fundus mucosa and pancreas but not in the remaining GI tract or brain. By means of RT-PCR, CCK-A receptor mRNA was demonstrated in the brain and the mucosa of the fundus, antrum, duodenum, and colon, kidney, pancreas and pancreatic islets. CCK-B receptor mRNA was detected by Northern blot analysis in the brain and the fundus mucosa but not in the rest of the digestive tract and not in the pancreas, pancreatic islets, or kidney. By RT-PCR, expression of CCK-B receptor mRNA could also be detected in antrum mucosa. In man, CCK-A receptor mRNA was detected in the brain, stomach, pancreas, and kidney, whereas CCK-B receptor mRNA was found in the brain, stomach, and pancreas but not in the kidney. Cloning and DNA-sequence analysis of the PCR-amplified rat and human CCK-A and CCK-B receptor DNA fragments, which cover the protein-encoding regions of the intracellular loop C3, showed complete sequence homology as compared with published rat and human sequences. CONCLUSIONS: It appears unlikely that CCK will have effects in the ileum, at least not effects mediated by CCK-A receptors. It also appears unlikely that physiologic concentrations of gastrin in the circulation will promote growth (or exert other effects) in the pancreas, duodenum, ileum, and colon, since CCK-B receptor mRNA is not expressed or is poorly expressed in these tissues.
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