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Biomedical subjects

B Akesson

Publications and source records attributed to B Akesson.

At least 73 records · Page 4Linked to original sources
PubMed1985

Selenium status in vegans and lactovegetarians.

Plasma and urinary selenium were determined among vegans, lactovegetarians and several groups of omnivorous subjects, using gas-liquid chromatography. Plasma Se was lower among lactovegetarians (0.80 (SD 0.18) mumol/l) than in the other groups (0.98 (SD 0.15) mumol/l). This was not related to Se intake, since the vegans had a lower and the lactovegetarians a higher intake of Se than omnivorous subjects in Sweden. Urinary Se was 0.36 (SD 0.10) mumol/d for controls, 0.17 (SD 0.10) mumol/d for vegans and 0.16 (SD 0.07) mumol/d for lactovegetarians. No relation between dietary Se and urinary Se was observed. Among vegetarians, plasma Se and urinary Se were correlated (r 0.51; P less than 0.05).

Adult↗
PubMed1985

Phthalate ester exposure--air levels and health of workers processing polyvinylchloride.

Exposure to phthalic acid esters (PAE; mainly di-(2-ethylhexyl), diisodecyl and butylbenzyl phthalates) of workers in a polyvinyl chloride processing industry ranged from 0.02 to 2 mg/m3 in different job categories. The workers excreted slightly but significantly higher levels of PAE metabolites in urine than controls. In 54 workers studied clinically, there were no indications of peripheral nerve or respiratory system effects. Some biochemical tests were abnormal; these should be studied further.

Adult↗
PubMed1985

Interaction between ascorbic acid and acetylsalicylic acid and their effects on nutritional status in man.

Healthy adults were given four diets, each one for one week: Low ascorbic acid diet, low ascorbic acid diet plus acetylsalicylic acid (3 g/d), high ascorbic acid diet (1 g/d) and high ascorbic acid diet plus acetylsalicylic acid. At low ascorbic acid intake, acetylsalicylic acid increased urinary ascorbic acid, but at high ascorbic acid intake, acetylsalicylic acid instead decreased urinary ascorbic acid. The latter effect was probably due to an inhibited intestinal absorbtion of ascorbic acid, and the former effect may reflect decreased protein binding and tissue uptake of ascorbic acid caused by acetylsalicylic acid. In no instance, acetylsalicylic acid affected plasma ascorbic acid. The effect of ascorbic acid on substances related to lipid peroxidation was investigated. The high ascorbic acid diets decreased plasma lipoperoxide and retinol binding protein. No change was observed in serum tocopherol, iron status, erythrocyte lipid fluorescence, plasma ceruloplasmin, urinary and plasma selenium and glutathione peroxidase activity. Thus, one-week supplementation of ascorbic acid seems to have only marginal effects on lipid peroxidation and antioxidant status.

Adult↗
PubMed1984

Hepatotoxic effects of anti-rheumatic drugs in cultured rat hepatocytes.

Drug-induced liver injury has been suggested as a possible mechanism for the liver damage in rheumatic diseases. To evaluate the role of direct toxic action of drugs on hepatocytes, the effects of salicylate, chloroquine, prednisolone and indomethacin on LDH leakage from cultured rat hepatocytes were studied. Exposure for 24 h to the first two drugs induced liver damage, as reflected by LDH release, at concentrations 2-10 times as high as the therapeutic plasma levels in humans. Indomethacin and prednisolone at concentrations approx 50-100-fold higher than the therapeutic plasma levels, were not toxic to cultured hepatocytes. The data suggest that direct a toxic effect on hepatocytes is one possible mechanism of hepatotoxicity for salicylate and chloroquine, especially since the exposure time is much longer in humans than in the experimental model used here.

Animals↗
PubMed1984

Effects of pectin and wheat bran on intraluminal pancreatic enzyme activities and on fat absorption as examined with the triolein breath test in patients with pancreatic insufficiency.

In totally pancreatectomized patients breath 14CO2 excretion after ingestion of 14C-labeled triolein was significantly increased by a granulated pancreatic enzyme preparation and was reduced when pectin was added to the enzyme supplement. In the same patients pectin reduced trypsin, lipase, and amylase activities of jejunal aspirates after a test meal supplemented with pancreatic enzyme substitution, which was shown to give good enzyme activities in the intestine. In patients with chronic pancreatitis, breath 14CO2 excretion was reduced by wheat bran, which also caused a reduction in lipase and amylase activities of duodenal aspirates after a test meal. The findings demonstrate the efficiency of treatment with a granulated pancreatic enzyme preparation in restoring intraluminal enzyme activities and fat absorption in patients with pancreatic insufficiency. They also show that pectin and wheat bran may induce fat malabsorption and inhibit digestive enzyme activities in vivo.

Adult↗
PubMed1983

Uptake of beta-hexosaminidase by nonparenchymal liver cells and peritoneal macrophages.

The uptake of beta-hexosaminidase (EC 3.2.1.30) in nonparenchymal liver cells (i.e. endothelial and Kupffer's cells) and peritoneal macrophages has been determined by an enzymatic assay. A considerable uptake was noted in nonparenchymal liver cells, whereas no measurable uptake was seen in peritoneal macrophages. The endothelial cells were more active in the uptake of beta-hexosaminidase than were the Kupffer's cells. The uptake of beta-hexosaminidase by nonparenchymal liver cells showed saturation kinetics and was competitively inhibited by mannan. These findings support the concept that a cell surface receptor on nonparenchymal liver cells mediates uptake of beta-hexosaminidase and suggests a difference in the receptor mechanisms on liver and peritoneal macrophages.

Animals↗
PubMed1983

Increased frequency of lymphocyte micronuclei in workers producing reinforced polyester resin with low exposure to styrene.

A new micronucleus method based on the analysis of lymphocytes with preserved cytoplasm revealed an increased frequency of micronuclei in 38 workers employed in a plant producing styrene-modified polyester resin as compared to the frequency in 20 referents (5.9 vs 3.6%). The time-weighted average of the styrene concentration in the workroom air varied between 1 and 36 ppm (mean 13 ppm) during the last year and correlated well to low urinary levels of mandelic acid, which ranged from 9 to 316 mg/g of creatinine (mean 65 mg/g of creatinine).

Adult↗
PubMed1981

Nutrient intake and health status of vegans. Chemical analyses of diets using the duplicate portion sampling technique.

A strict vegetarian diet [vegan diet (VD)] was investigated. Six middle-aged vegans (three men and three women) collected copies of 24-h diets using the duplicate portion sampling technique. By chemical analyses, the nutrient composition was determined in detail and compared with corresponding figures of a normal mixed Swedish diet. In the VD 30% of the energy originated from fat compared with 40% in normal Swedish mixed diet (MD). Linoleic acid was the dominant fatty acid (60% of total fat in VD versus 8% in MD). The VD contained 24 g protein/1000 kcal compared to 30 g/1000 kcal in MD, but the intake of essential amino acids by the vegans exceeded the recommendations. Dietary fiber was about 5 times higher in the vegan diet (29 versus 6 g/1000 kcal) and sucrose similar to MD (18 versus 21 g/1000 kcal). Among the inorganic nutrients the concentration of calcium (351 versus 391 mg/1000 kcal) and sodium (53 versus 49 mmol/1000 kcal) were similar in both types of diets but the amount of potassium (56 versus 30 mmol/1000 kcal, magnesium (300 versus 110 mg/1000 kcal), iron (9 versus 6.5 mg/1000 kcal), zinc (6.5 versus 4.7 mg/1000 kcal), and copper (2 versus 0.7 mg/1000 kcal) were nearly doubled. Iodine (39 versus 156 micrograms/1000 kcal and selenium (5 versus 17 micrograms/1000 kcal) were much lower in the VD, selenium even being undetectable in several 24-h diets. The VD was rich in folic acid (301 versus 90 micrograms/1000 kcal in MD) but the intake of vitamin B12 was only 0.3 to 0.4 microgram/day (MD: 3 to 4 micrograms/day). No clinical signs of nutritional deficiency were observed in the vegans. Serum protein levels of the vegans as well as their serum lipoproteins were near the lower range of the reference group. In addition, none of the vegans was overweight and their blood pressures were low for their age.

Blood Pressure↗
PubMed1979

Relative efficiency of anticodons in reading the valine codons during protein synthesis in vitro.

Using a protein synthesizing in vitro system programmed with MS 2-RNA, the relative efficiency (in the presence of each other) of valine tRNAs with the anticodons U*AC (U* represents 5-oxyacetic acid uridine monophosphate), GAC, and IAC to read the valine codons was investigated. An anticodon which can read all three positions of the codon according to the rules of Watson-Crick base-pairing and the wobble hypothesis is an order of magnitude more efficient than an anticodon which misreads the codon by reading only the first two positions and presumably disregards the third nucleotide of the codon. There are two seeming exceptions to this behavior: the anticodon U*AC reads the codon GUU quite efficiently and IAC is as effective as U*AC in reading the codon GUG. The significance of these exceptions is evaluated with respect to the organization and evolution of the genetic code.

Anticodon↗
PubMed1979

Effect of sphingosine and other amphiphilic amines on the biosynthesis of phosphatidylethanolamine and other glycerolipids in isolated rat hepatocytes.

The importance of ethanolamine and sphingosine as precursors of phosphoethanolamine was investigated by incubating them with [3H]glycerol and isolated rat hepatocytes. Sphingosine (0.1--0.5 mM) stimulated the synthesis of phosphatidylethanolamine from [3H]glycerol, but the stimulation by ethanolamine was more pronounced. Furthermore, more phosphoethanolamine accumulated in the heptatocytes after incubation with ethanolamine than after incubation with sphingosine. It is concluded that ethanolamine is the most important phosphoethanolamine precursor in rat liver. Higher concentrations of sphingosine caused accumulation of [3H]phosphatidate and inhibition of total glycerolipid synthesis in isolated hepatocytes, when incubated in the presence of [3H]glycerol. These effects were very similar to those of fenfluramine and norfenfluramine described previously. Simpler cationic amphiphilic amines, like oleoylamine and octadecyltrimethylammonium bromide, also caused these effects. Variation of alkyl chain length and amphiphile charge showed that both a positive charge and a certain alkyl chain length were necessary for interference with phosphatidate metabolism. A much wider range of compounds inhibited total glycerolipid synthesis from [3H]glycerol.

Amines↗
PubMed1979

Lipid composition and metabolism in liver and brain of vitamin B12-deficient rat sucklings.

1. Rat sucklings (18-d-old) bred from vitamin B12-deprived dams were compared with vitamin B12-supplemented dams' offspring, which were considered normal rat sucklings. 2. The vitamin B12-deficient rat sucklings had lower body-weight, liver weight and brain weight. 3. Vitamin B12 deficiency was also evident from the tenfold lower concentrations of vitamin B12 in liver and cerebellum. 4. The concentration of liver lipid was markedly increased in vitamin B12-deficient rats; triacylglycerol accounted for most of the increase. In brain the lipid concentration was slightly decreased (less than 0.05). 5. The methylation of ethanolamine phosphoglyceride to choline phosphoglyceride was reduced in both liver and brain in vitamin B12-deficient rats, as measured after the administration of [14C]ethanolamine. A slight decrease in choline phosphoglyceride concentration could be a consequence of this finding. The composition of phospholipids was otherwise normal. 6. Odd-chain fatty acids (pentadecanoate and heptadecanoate) accumulated in both liver and brain of the vitamin B12-deficient rat sucklings and constituted approximately 1% of total fatty acid. 7. The biosynthesis of fatty acid and cholesterol from intraperitoneally-injected 3H2O and [14C]propionate was unchanged in vitamin B12 deficiency.

Animals↗
PubMed1979

Micromethods for analysis of lipids in endomyocardial biopsy specimens.

Triglycerides and phospholipids extracted from endomyocardial biopsy specimens were quantitated with sensitive photometric methods and the fatty acid composition of phospholipids was determined after separation of the methyl esters by gas chromatography. The degree of triglyceride accumulation was expressed as the molar ratio triglyceride/phospholipid since in most cases the phospholipid concentration is relatively constant. The representativity of the analysis of endomyocardial biopsy was investigated by comparing lipid analyses of large and small myocardial specimens obtained at necropsy. The methods described may be valuable tools in studies on metabolic disturbances in different cardiomyophaties.

Biopsy↗
PubMed1978

Simultaneous purification and some properties of aspartate: tRNA ligase and seven other amino-acid:tRNA ligases from Escherichia coli.

A procedure is described for the purification of the aspartate:tRNA ligase from Escherichia coli to a stage where it was homogeneous by polyacrylamide gel electrophoresis. From the same batch of E. coli the lysine, phenylalanine and serine ligases were obtained in an apparently homogeneous form while the alanine, glutamine, leucine and valine enzymes had a purity varying from 20% to 80%. Aspartate: tRNA ligase, which has not been obtained in a highly purified form before, has been characterized in terms of its molecular parameters.

Aspartic Acid↗