| 1. |
- Clarke, Robert, et al.
(författare)
-
Lowering blood homocysteine with folic acid based supplements : Meta-analysis of randomised trials
- 1998
-
Ingår i: British Medical Journal. - : BMJ. - 0959-8146. ; 316:7135, s. 894-898
-
Forskningsöversikt (refereegranskat)abstract
- Objective: To determine the size of reduction in homocysteine concentrations produced by dietary supplementation with folic acid and with vitamins B-12 or B-6. Design: Meta-analysis of randomised controlled trials that assessed the effects of folic acid based supplements on blood homocysteine concentration. Multivariate regression analysis was used to determine the effects on homocysteine concentrations of different doses of folic acid and of the addition of vitamin B-12 or B-6. Subjects: Individual data on 1114 people included in 12 trials. Findings: The proportional and absolute reductions in blood homocysteine produced by folic acid supplements were greater at higher pretreatment blood homocysteine concentrations (P < 0.001) and at lower pretreatment blood folate concentrations (P < 0.001). After standardisation to pretreatment blood concentrations of homocysteine of 12 μmol/l and of folate of 12 nmol/l (approximate average concentrations for Western populations), dietary folic acid reduced blood homocysteine concentrations by 25% (95% confidence interval 23% to 28%; P < 0.001), with similar effects in the range of 0.5-5 mg folic acid daily. Vitamin B-12 (mean 0.5 mg daily) produced an additional 7% (3% to 10%) reduction in blood homocysteine. Vitamin B-6 (mean 16.5 mg daily) did not have a significant additional effect. Conclusions: Typically in Western populations, daily supplementation with both 0.5-5 mg folic acid and about 0.5 mg vitamin B-12 would be expected to reduce blood homocysteine concentrations by about a quarter to a third (for example, from about 12 μmol/l to 8-9 μmol/l). Large scale randomised trials of such regimens in high risk populations are now needed to determine whether lowering blood homocysteine concentrations reduces the risk of vascular disease.
|
|
| 2. |
- Trondman, Anna-Kari, et al.
(författare)
-
Pollen-based quantitative reconstructions of Holocene regional vegetation cover (plant-functional types and land-cover types) in Europe suitable for climate modelling
- 2015
-
Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 21:2, s. 676-697
-
Tidskriftsartikel (refereegranskat)abstract
- We present quantitative reconstructions of regional vegetation cover in north-western Europe, western Europe north of the Alps, and eastern Europe for five time windows in the Holocene [around 6k, 3k, 0.5k, 0.2k, and 0.05k calendar years before present (bp)] at a 1 degrees x1 degrees spatial scale with the objective of producing vegetation descriptions suitable for climate modelling. The REVEALS model was applied on 636 pollen records from lakes and bogs to reconstruct the past cover of 25 plant taxa grouped into 10 plant-functional types and three land-cover types [evergreen trees, summer-green (deciduous) trees, and open land]. The model corrects for some of the biases in pollen percentages by using pollen productivity estimates and fall speeds of pollen, and by applying simple but robust models of pollen dispersal and deposition. The emerging patterns of tree migration and deforestation between 6k bp and modern time in the REVEALS estimates agree with our general understanding of the vegetation history of Europe based on pollen percentages. However, the degree of anthropogenic deforestation (i.e. cover of cultivated and grazing land) at 3k, 0.5k, and 0.2k bp is significantly higher than deduced from pollen percentages. This is also the case at 6k in some parts of Europe, in particular Britain and Ireland. Furthermore, the relationship between summer-green and evergreen trees, and between individual tree taxa, differs significantly when expressed as pollen percentages or as REVEALS estimates of tree cover. For instance, when Pinus is dominant over Picea as pollen percentages, Picea is dominant over Pinus as REVEALS estimates. These differences play a major role in the reconstruction of European landscapes and for the study of land cover-climate interactions, biodiversity and human resources.
|
|
| 3. |
|
|
| 4. |
- Hugander, A., et al.
(författare)
-
Total body hyperthermia induced by a computerized microwave technique : studies in normal rats and in rats with liver tumors.
- 1983
-
Ingår i: Anticancer research. - 0250-7005. ; 3:3, s. 161-165
-
Tidskriftsartikel (refereegranskat)abstract
- A computerized system for inducing total body hyperthermia by microwave irradiation was tested in rats. The tolerance to hyperthermia at different temperatures and fractions was studied as well as its effect on the growth of transplanted adenocarcinomas in the liver. Survival results indicated that 41.5 degrees C was maximum tolerated temperature both after single and repeated one hour exposures. Besides the high mortality with a greater temperature (42 degrees C) there was a significant rise in S-aspartate-amino-transferase (S-ASAT) and S-beta-hexosaminidase (beta-nagas) indicating damage of normal cells. No significant reduction of tumor volume could be registered after treatment with total body hyperthermia (41.5 degrees C) for one hour three times during a 24 hour period.
|
|
| 5. |
- Agardh, Carl-David, et al.
(författare)
-
Urinary N-acetyl-beta-D-glucosaminidase activity does not predict development of diabetic nephropathy
- 1987
-
Ingår i: Diabetes Care. - : American Diabetes Association. - 1935-5548 .- 0149-5992. ; 10:5, s. 604-606
-
Tidskriftsartikel (refereegranskat)abstract
- Urinary activity of N-acetyl-beta-D-glucosaminidase (NAG) has been suggested as a marker for diabetic nephropathy. In this study, urinary activity of NAG was measured with an interval of 5 yr in 36 insulin-dependent diabetic subjects to evaluate its predictive value for development of diabetic nephropathy. During the observation period, 9 patients developed detectable signs of diabetic nephropathy. In these patients, urinary albumin concentration had increased to 503 +/- 185 mg/L, compared to 16 +/- 1 mg/L in patients without nephropathy (P less than .01; means +/- SE), and the fractional albumin excretion rate was 0.21 +/- 0.07 X 10(-3), compared to 0.01 +/- 0.00 X 10(-3) (P less than .01). However, the activity of urinary NAG was not different in these patients compared with the patients without nephropathy (0.69 +/- 0.15 and 0.61 +/- 0.09 U/mmol creatinine, respectively). Furthermore, no increase in the activity of urinary NAG was seen during the observation period in either group. We concluded that the urinary activity of NAG is not related to the development of microalbuminuria and therefore cannot be used as a predictor for the development of diabetic nephropathy.
|
|
| 6. |
- Agardh, Elisabet, et al.
(författare)
-
Effects of inhibition of glycation and oxidative stress on the development of cataract and retinal vessel abnormalities in diabetic rats
- 2000
-
Ingår i: Current Eye Research. - 0271-3683. ; 21:1, s. 543-549
-
Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To study effects of inhibition of glycation, and oxidative stress on the development of cataract and retinal vessel abnormalities in diabetic rats. METHODS: Diabetes was induced in male Wistar rats with streptozocin (STZ; 60 mg/kg BW, i.p.). Diabetic as well as strain matched control rats were fed 1) a normal diet, 2) addition of aminoguanidine in the drinking water (0.5 g/l for diabetic rats and 1.0 g/l for control rats) or 3) probucol in the pellets (1% w/w). After 6 months, the number of acellular vessels, endothelial cells and pericytes were counted in trypsin digested retinal vessel preparations, and the total retinal tissue amount of glutathione (GSH) and cysteine was measured with HPLC. RESULTS: Cataract formation occurred after 13 weeks in diabetic animals compared with 17 weeks for those treated with aminoguanidine, and 16 weeks for those treated with probucol (p < 0.001 in both cases). Aminoguanidine inhibited the formation of acellular collapsed capillary strands, 9 (3-14) vs. 18 (12-262) (median, range) per quadrant in untreated diabetic rats (p = 0.004), while probucol did not have any effect. Neither aminoguanidine, nor probucol influenced the endothelial/pericyte ratio. Diabetes caused a reduction in the GSH/cysteine ratio (10.7 +/- 0.6 vs. 15.3 +/- 1. 5) (mean +/- SD; p < 0.001). Probucol partly restored this imbalance (p < 0.05) whereas aminoguanidine did not. CONCLUSIONS: The results indicate that cataract formation in diabetes involves both glycation and oxidative stress processes. The reduced formation of acellular collapsed capillary strands by aminoguanidine suggests a potential role for glycation in vascular damage. The positive effect of probucol on cysteine/GSH metabolism imbalance indicates that derangements of one of the retinal defense systems against oxidative stress can be normalized by antioxidants.
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
- Andersson, Ingvar B., et al.
(författare)
-
Återförsurning av sjöar : Observerade och förväntade biologiska och kemiska effekter
- 2002
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Denna rapport är en översiktlig genomgång av de idag tillgängliga, delvis publicerade, experimentella erfarenheterna av kemiska och biologiska effekter vid återförsurning i ytvatten där kalkning avbrutits. Sammanställningen har genomförts i avsikt att bredda kunskapsunderlaget för diskussioner om tänkbara effekter i samband med att kalkningen upphör i vissa ytvatten. Som bakgrundsdokument är dessutom en litteraturöversikt bifogad, vilken även inkluderar övrig litteratur rörande försurning - kalkning som kan anses ha en viss allmän relevans för kunskapsläget avseende återförsurning av kalkade vatten (se Appendix). Resultatet från hittills genomförda fältstudier av återförsurning, endast tre stycken av någon större omfattning i Sverige, visade att stora förändringar inträdde snabbt. Utvecklingen gick mot förhållanden liknande de i det sura tillståndet, med både negativ utveckling av ekosystemet och en påtaglig haltökning av aluminium m.fl. metaller i vattnet. Experimentell försurning av vattnet över sedimentproppar visade att tidigare deponerade metaller kan lösas ut från sedimenten. De hittills genomförda återförsurningsstudierna utfördes mestadels i gravt försurningsskadade sjöar, i ett fall också efter relativt kortvarig kalkning, och kan därför vara ett otillräckligt underlag för att kunna generalisera de effekter som kan uppstå vid återförsurning av kalkade sjöar. Många av de observerade biologiska förändringarna sammanfaller med vad som generellt observerats i samband med försurning av sjöar men vissa biologiska förändringar var dock avvikande och i några fall av delvis oväntad natur. Omfattningen och hastigheten i de senare fallen indikerade att de aktuella organismsamhällena saknade vissa reglerande mekanismer (interaktioner) och därför genomgick en utveckling präglad av instabilitet under återförsurningen. Det sura svavelnedfallet har minskat med ca. 60 % sedan 70-talet vilket medfört en proportionell återhämtning av vattenkemi och även biota i vissa ytvatten inom regioner som haft kortvarigt eller litet överskridande av den kritiska försurningsbelastningen (ringa markförsurning). Däremot har den minskade belastningen på ytvattnen hittills resulterat i små positiva förändringar inom de mest försurade områdena i södra Sverige. Trots en halvering av sulfathalt och surhet i många sjöar och vattendrag, har få biologiska förändringar observerats, då pH värden <5 och toxiska aluminiumhalter fortfarande medför negativa effekter på de flesta känsliga organismer. Modellsimuleringar har visat att återhämtningen inom sådana områden kommer att ta mycket lång tid (10- tals till kanske 100 år) eftersom försurningen av marken varit omfattande. Inom dessa områden, med en låg kritisk belastningsgräns, krävs ytterligare reduktion av belastningen samt i vissa fall t.o.m. kompletterande åtgärder som markkalkning. Även depositionen av flera tungmetaller har minskat kraftigt under de senaste decennierna, särskilt den långdistanstransporterade andelen, men hur stora förändringar detta medfört på ytvattnens innehåll av tungmetaller är i dagsläget osäkert, eftersom längre tidsserier från skogssjöar saknas inom miljöövervakningen.Av de kalkade sjöarna i Sverige, ca. 7500 st, beräknas mer än 1700 sjöar kunna få pHvärden under 5,4 och förlora alkaliniteten om kalkningar upphör i nuläget. De flesta sjöarna som kan komma att återförsuras till pH-värden under 5,4 är belägna inom de områden i sydvästra Sverige som är mest försurningsskadade. Stoppad kalkning i dessa sjöar skulle medföra långtgående återförsurning inom en tidsrymd av ca. 2 - 3 gånger den teoretiska omsättningstiden, för många sjöar motsvarande 3 till 9 år. Sannolikt skulle många av de effekter som observerats i de här genomgångna återförsurningsstudierna uppstå. Även sjöar som skulle återförsuras till pH-värden mellan 5,4 och 6,0 kan riskera att få skador på populationer av känsligare arter. Drygt 4000 sjöar skulle få pH-värden under 6,0 vid en stoppad kalkning. I sjöar med från början måttlig försurning kan en återförsurning förväntas resultera i tämligen marginella eller inga effekter med hänsyn till minskad försurningsbelastning och ringa markförsurning. Denna grupp omfattar en del av de ca. 3500 sjöar som åtminstone på längre sikt inte skulle riskera att få pH-värden <6,0 vid en stoppad kalkning. I de flesta sådana fall skulle endast de allra känsligaste arternas populationer riskera att påverkas. Surstötar, d.v.s. episodisk tillförsel av markant surare vatten i samband med kraftiga regn, snösmältning eller efter längre torrperioder, utgjorde i försurningens inledningsskede en viktig faktor för uppkomsten av biologiska skador eftersom särskilt höga halter av toxiskt oorganiskt aluminium förekom i samband med sådana situationer. Sannolikt kan surstötarna utgöra ett betydande problem även under återhämtningsfasen, då risk föreligger för fortsatta utflödena av höga aluminiumhalter i många sjöar och framförallt vattendrag inom de områden där markförsurningen kvarstår länge varvid en positiv biologisk utveckling kommer att motverkas. Problem kan även fortsättningsvis uppträda inom vissa nordligare lågbelastade regioner där främst hydrologiska faktorer samt kraftiga utflöden av organiska syror bidrar till uppkomsten av surstötar med inflöden av förhöjda halter av aluminium. Högre halter av komplexbildande organiska anjoner kan dock i sådana fall bidra till en lägre toxisk effekt. I denna rapport föreslås en översyn av kalkningsverksamheten, liksom rekommendationer av urvalskriterier för olika ytvatten om det blir aktuellt med åtgärder som medför en minskad kalkning. Slutligen föreslås forskningsinsatser för att belysa en del av de oklarheter som för närvarande råder om effekterna i samband med återförsurning.
|
|
| 10. |
|
|
| 11. |
- Chester, Alan, et al.
(författare)
-
A comparison of the alpha-L-fucosidase activities of human liver and serum
- 1977
-
Ingår i: Biochimica et Biophysica Acta. - 0006-3002. ; 485:1, s. 147-155
-
Tidskriftsartikel (refereegranskat)abstract
- Human liver alpha-L-fucosidase (alpha-L-fucoside fucohydrolase, EC 3.2.1.51) has been separated into four components by chromatography on Sephadex G-150 or DEAE-cellulose. These components differ in their relative stability to heat and acid treatment, and their response to neuraminidase. The serum enzyme was devoid of high molecular weight activity and probably contained more sialic acid residues than the corresponding enzyme from liver. All the liver components tested were able to liberate fucose from 2'-fucosyllactose but not fucose from other oligosaccharides.
|
|
| 12. |
- Chester, Alan, et al.
(författare)
-
A new N-acetyl-beta-D-hexosaminidase disease with late onset of progressive neurological symptoms
- 1979
-
Ingår i: Human Heredity. - 1423-0062. ; 29:2, s. 124-128
-
Tidskriftsartikel (refereegranskat)abstract
- Clinical data are presented on a 30-year-old male with normal early development (4-5 years) but subsequent progressive impairment of psychomotor functions. He has marked kyphoscoliosis and talipes calcaneo-valgus. The organs appear normal and the patient can walk unaided and feed himself although he does not recognize his parents. He has normal fundi oculi. Biochemical data show an absence of mucopolysacchariduria and very low but detectable levels of N-acetyl-beta-D-hexosaminidase in serum and leucocytes. The clinical symptoms are much milder than would normally be expected from such a profound enzyme deficiency (Sandhoff disease).
|
|
| 13. |
- Chester, Alan, et al.
(författare)
-
The common identity of five glycosidases in human liver
- 1976
-
Ingår i: Biochimica et Biophysica Acta. - 0006-3002. ; 429:2, s. 517-526
-
Tidskriftsartikel (refereegranskat)abstract
- An enzyme has been isolated from human liver by DEAE-cellulose chromatography and has been shown by competitive substrate inhibition to be capable of hydrolysing synthetic beta-D-galactosides, beta-D-glucosides, beta-D-fucosides, beta-D-xylosides, and alpha-L-arabinosides. Another form of alpha-L-arabinosidase activity elutes with the major beta-D-galactosidase component on DEAE-chromatography, but has a different identity on the basis of its stability at 4 degrees C. Liver samples from patients with Gaucher's disease are deficient in beta-D-fucosidase as well as beta-D-glucosidase activity.
|
|
| 14. |
|
|
| 15. |
|
|
| 16. |
|
|
| 17. |
- Holmin, T, et al.
(författare)
-
The influence of total hepatectomy on cerebral energy state, ammonia-related amino acids of the brain and plasma amino acids in the rat
- 1983
-
Ingår i: European Journal of Clinical Investigation. - : Wiley. - 0014-2972 .- 1365-2362. ; 13:3, s. 215-220
-
Tidskriftsartikel (refereegranskat)abstract
- The influence of total hepatectomy on cerebral energy state, ammonia-related amino acids of the brain tissue and plasma amino acids was studied in anaesthetized rats after total hepatectomy. The hepatectomy was performed with the aid of a microsurgical three-stage procedure. In the first stage, division of the inferior vena cava was performed. In the second stage 4 weeks later a porta-caval anastomosis was constructed, followed after 1 week by a total hepatectomy. The brain energy state, defined as the concentrations of phosphocreatine, ATP, ADP and AMP, was unchanged 4 h after the hepatectomy. Plasma amino acids did not differ significantly between hepatectomized and shunted control rats. On the other hand, clear-cut increases in the concentrations of glutamine, and decreases in the concentrations of glutamate and aspartate, were observed in the fronto-parietal part of the cerebral cortex and the brain stem. These changes might explain the minor manifestations of cerebral dysfunction in the early phase of the hepatectomized state.
|
|
| 18. |
- Larsson, J, et al.
(författare)
-
Hyperhomocysteinemia and the MTHFR C677T mutation in central retinal vein occlusion
- 2000
-
Ingår i: Acta Ophthalmologica Scandinavica. - : Wiley. - 1395-3907. ; 78:3, s. 3-340
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Hyperhomocysteinemia is a factor that predisposes to thrombosis, and the C677T mutation in methylene-tetrahydrofolate reductase (MTHFR) is known to give increased plasma homocysteine. We wanted to investigate if these factors were overrepresented in a group of patients with central retinal vein occlusion.METHODS: 116 patients with a history of central retinal vein occlusion were examined for the presence of hyperhomocysteinemia and the MTHFR C677T mutation.RESULTS: Compared to the control groups, there was no significant increase, neither in plasma homocysteine nor in the frequency of the MTHFR C677T mutation in the patients. Even when we looked selectively at the young patients, age less than 50 years, no difference could be detected.CONCLUSION: It seems that neither hyperhomocysteinemia nor the MTHFR C677T mutation is an important risk factor for the aetiology of central retinal vein occlusion.
|
|
| 19. |
|
|
| 20. |
- Nilsson, Karin, et al.
(författare)
-
Role of impaired renal function as a cause of elevated plasma homocysteine concentration in psychogeriatric patients.
- 2002
-
Ingår i: Scandinavian Journal of Clinical & Laboratory Investigation. - : Informa UK Limited. - 1502-7686 .- 0036-5513. ; 62:5, s. 9-385
-
Tidskriftsartikel (refereegranskat)abstract
- In previous studies a high frequency of elevated plasma tHcy concentrations has been observed in psychogeriatric patients (40-50%), but the main cause of these increased concentrations could not be established with certainty. Impaired renal function could partly contribute to elevated plasma tHcy concentrations in psychogeriatric patients. Therefore, in the present study, cystatin C was used as a sensitive marker for glomerular filtration. A linear regression analysis including age, blood folate, serum cobalamin, serum cystatin C and serum creatinine showed that only serum creatinine (p<0.001) and blood folate (p<0.001) independently predicted plasma tHcy concentration. However, about 44% of the patients with elevated plasma tHcy concentrations had signs of reduced glomerular filtration rate, as judged by increased serum cystatin C, whereas only about 13% of the patients with normal concentrations of plasma tHcy had signs of reduced glomerular filtration rate. This finding indicates that renal impairment may to some extent contribute to the elevated plasma tHcy concentration, even though serum cystatin C did not independently predict plasma tHcy concentration.
|
|
| 21. |
- Nilsson, Karin, et al.
(författare)
-
Treatment of cobalamin deficiency in dementia, evaluated clinically and with cerebral blood flow measurements
- 2000
-
Ingår i: Aging. - 0394-9532. ; 12:3, s. 199-207
-
Tidskriftsartikel (refereegranskat)abstract
- We investigated the relation between cobalamin deficiency, clinical changes and brain function in dementia patients. On admittance to the clinic, 24 patients had cobalamin deficiency, and dementia with additional symptoms of delirium. During cobalamin supplementation, the patients underwent repeated regional cerebral blood flow (rCBF) studies, psychiatric evaluations, and in some cases assessment with MMSE and the Organic Brain Syndrome scale. Fifteen patients who showed mild to moderate dementia improved clinically, and also showed a concomitant increase in their general CBF after treatment. In contrast, 9 patients who were severely demented showed no obvious clinical improvement, and no general blood flow change, although some regional flow increases were seen in sensory motor areas. We conclude that symptoms which probably indicated superimposed delirium such as clouding of consciousness, disorientation and clinical fluctuation, responded to the vitamin B12 supplementation, while the underlying dementia condition remained basically unchanged. The clinical improvement was also mirrored in general and focal rCBF changes.
|
|
| 22. |
|
|
| 23. |
- Selden, A., et al.
(författare)
-
Trichloroethylene exposure in vapour degreasing and the urinary excretion of N-acetyl-beta-D-glucosaminidase
- 1993
-
Ingår i: Archives of Toxicology. - 0340-5761. ; 67:3, s. 224-6
-
Tidskriftsartikel (refereegranskat)abstract
- In order to elucidate the potential nephrotoxicity of low level occupational exposure to trichloroethylene (TRI), urine analysis of the tubular enzyme N-acetyl-beta-D-glucosaminidase (U-NAG) was included in a cross-sectional study of metal degreasers in central Sweden. Eighty-six percent of 8-h TRI in air measurements were well below 50 mg/m3. Normal levels of NAG were found in morning urine samples from 29 workers compared to a historical reference group. A weak positive correlation (r = 0.48; P < 0.01) was observed between U-NAG activity and the concentration of the TRI metabolite trichloroacetic acid in urine but not with other estimates of recent or long-term exposure. In conclusion, TRI does not seem to be nephrotoxic at low exposure levels.
|
|
