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Biomedical subjects

U Eriksson

Publications and source records attributed to U Eriksson.

At least 145 records · Page 8Linked to original sources
PubMed1981

Failure of successful intrasplenic transplantation of islets from lean mice to cure obese-hyperglycaemic mice, despite islet growth.

Implantation of allogeneic pancreatic islets encapsulated in Millipore diffusion chambers has been reported to normalize the obese-hyperglycaemic syndrome in mice. In the present study, both young and adult ob/ob mice remained hyperglycaemic and gained weight after intrasplenic implantation of 500 isogeneic islets isolated from lean mice. Such islets normalized the elevated blood-glucose of alloxan-diabetic lean mice. Morphometric analysis of the intrasplenically implanted islets showed that the mean islet volume in the ob/ob mice was five times larger than that of the lean, non-diabetic mice. Immunocytochemical staining of the spleens showed an increased proportion of B-cells in the enlarged, intrasplenic islets in the ob/ob mice. Moreover, autoradiographical examination of these islets demonstrated the presence of several labelled cells. These results suggest that the growth of the implanted "lean" islets is due to extrapancreatic factors which stimulate islet cell replication in the obese-hyperglycaemic mouse.

Animals↗
PubMed1981

Glucagon production by cultured pancreatic islets: effects of different culture conditions and media.

Various conditions for tissue culture of collagenase-isolated mouse pancreatic islets were studied for their effects on the glucagon production of the cultured specimens. Culture media containing heat-treated bovine calf serum degraded [125I]glucagon to a much less extent than those supplemented with untreated serum. Addition of aprotinin to the heat-treated serum gave a further reduction of the [125I]glucagon degradation in the culture medium. A similar supplementation of Medium 199, used for culture of isolated islets, resulted in the most extensive glucagon accumulation in the culture medium. Islets cultured free-floating or attached to the bottom of the culture dishes contained similar amounts of glucagon. However, the free-floating islets released less glucagon when tested in short-term experiments performed at the end of the 1 wk culture period. A comparison between different culture media showed that islets cultured in RPMI-1640 had the highest glucagon content and released most glucagon to the culture medium. Moreover, these islets responded most actively to an acute arginine challenge at the end of the culture period. The present data suggest that the optimal conditions for culture of isolated islets aimed at studies of glucagon production may be obtained by using a culture medium consisting of RPMI-1640 supplemented with both a proteinase inhibitor and heat-inactivated serum.

Animals↗
PubMed1981

Salmonella bacteriophage glycanases: endorhamnosidase activity of bacteriophages P27, 9NA, and KB1.

Four bacteriophages, P22, P27, 9NA, and KB1, active on smooth Salmonella strains belonging to serogroups A, B, and D1 were investigated for endoglycosidase activity and specificity in enzyme hydrolysis assays. Purified phage was incubated with phenol-water-extracted lipopolysaccharide preparations which had been partially delipidated. Dialyzable oligosaccharides, released by phage glycosidase activity, were analyzed by sugar and methylation analyses. Phages P27, 9NA, and KB1, as well as P22 assayed earlier (U. Eriksson et al., J. Gen. Virol. 43: 503-511, 1979; S. Iwashita and S. Kanegasaki, Biochem. Biophys. Res. Commun. 55:403-409, 1973), were all found to have phage-associated endorhamnosidase activity hydrolyzing the O-polysaccharide chain common to bacteria of serogroups A, B, and D1 [Formula: see text] between the l-rhamnose and d-galactose residues. The nature of the R monosaccharide, abequose, tyvelose, or paratose, had no effect on the activity or specificity of the endorhamnosidase, whereas a change of the d-galactose --> d-mannose linkage from alpha1,2 to alpha1,6 made the O-polysaccharide chain resistant to the endorhamnosidases. Modification of the O chain by glucosylation of the d-galactose residue at O-4 or O-6 revealed two glycosidase specificities: the phage P22 and P27 enzymes hydrolyzed O chains glucosylated at O-4 but not O-6, whereas the phage 9NA and KB1 enzymes hydrolyzed chains glucosylated at O-6 but not O-4. Phage KB1, like P22 and P27, had a short, noncontractile tail containing a base plate with tail spikes (morphologically Bradley group C), whereas 9NA had a long, flexible tail ending with a base plate-like appendage (Bradley group B), which suggests that the endorhamnosidase activity can be associated with different tail structures.

Glycoside Hydrolases↗
PubMed1981

Transcultural aspects of depressive symptomatology.

The following is a presentation of the first results of a cross-cultural study of depressive symptomatology, within the framework of a larger research project which is still in progress. Southern Italian and northern Swedish depressed patients completed a self-rating scale for depression and were rated by the doctors using a subscale of the Comprehensive Psychological Rating Scale. In the doctors' ratings Italian patients scored higher for variables referring to motor retardation and hypochondriasis, and Swedish patients for variables referring to inability to feel and agitation. These findings were in line with expectations. In contrast, in the self-ratings Swedish patients scored higher for the variables weight loss, tachycardia and agitation and Italian patients for hopelessness and loss of interest and dissatisfaction. This discrepancy between results in self-ratings and doctors' ratings might reflect cultural differences either in the way patients in the two countries are able to express verbally their symptoms or in the way doctors from the two countries give weight to different symptoms. Taking the results of the two ratings together as a general measure of the severity of the depressive disorder, patients in the two places appeared to be quite alike. Since the two centers are engaged in comprehensive investigations of depressed patients, the last-mentioned finding suggests that the populations in the two centers are comparable as concerns severity.

Adult↗
PubMed1980

Properties of purified papain-solubilized rat AgB antigens and reactivity of a xenoantiserum against the isolated antigens.

Rat AgB transplantation antigens were isolated after papain digestion of spleens from the inbred strain Hooded Lister. Both subunits of the AgB antigens were present in the purified material. Some physical characteristics of the antigens have been determined. An antiserum, raised in a rabbit, against the purified material reacted exclusively with AgB antigens on splenocytes but detected novel structures on both adult and embryonic fibroblasts. These structures, antigenically related to AgB antigens, were not detected on plasmacytoma or hepatoma cells, nor did they display any antigenic similarity with rat beta 2-microglobulin. Radioimmunoassays specific for the AgB antigen heavy chain and for beta 2-microglobulin, respectively, were used to estimate the contents of these antigens in several tissues. Spleen and thymus exhibit the largest density, while brain is almost devoid of these antigens.

Animals↗
PubMed1980

Lung maturation in fetuses of diabetic rats.

Pulmonary maturation in diabetic pregnancy has been studied in the 20-day-old fetuses of manifest diabetic rats. The animals were either untreated or treated with insulin. The diabetic state was induced by a single IV injection of streptozotocin given about 2 wk before the onset of pregnancy. The biosynthesis of lung surfactant was estimated by monitoring the rate of incorporation of [methyl-3H]choline into phosphatidylcholine and lysophosphatidylcholine in fetal lung slices. In the untreated group, the biosynthesis of both phosphatidylcholine and lysophosphatidylcholine were decreased in the fetal lung. Insulin treatment abolished the decrease in the phosphatidylcholine biosynthesis, whereas the lysophosphatidylcholine biosynthesis reamined depressed. Light and transmission electron microscopical studies indicated a delayed pulmonary maturation in the untreated offspring accompanied by a decreased cytoplasmic content of glycogen in the alveolar epithelial cells.

Animals↗
PubMed1980

Glucagon biosynthesis in isolated pancreatic islets of mice and guinea pigs.

To further investigate the regulation of glucagon biosynthesis in mammalian A2-cells, we have studied the incorporation of [3H]-tryptophan into acid alcohol extracts of isolated pancreatic islets of guinea pig and mouse. Gel chromatography on Sephadex G-50 indicated that labelled proteins, migrating either with the void volume (peak I) or in region (peak II) between the void volume and the insulin marker, were formed during a 6h incubation of the islets. However, a period of at least two days in tissue culture was required before the islets showed any significant accumulation of labelled protein eluting in a position corresponding to that of pancreatic glucagon (peak III). Addition of glucose (16.7 mM) enhanced the incorporation into all chromatograph fractions during the culture period. Binding of gel chromatographed proteins Sepharose coupled anti-glucagon antibodies indicated that both guinea pig and mouse islets contained only small amounts of labelled, immunoreactive proteins eluting with either peak I or peak II. However, proteins eluting with peak III contained 6-8 times more lbelled, immunoreactive material than any of the other peaks. Total glucagon immunoreactivity was abundant in peaks I and II but less evident in peak II. The results of pulse-chase experiments provided no convincing evidence for a precursor-product relationship between larger proteins and glucagon. However, the heterogeneity of the putative precursor pool, as evidenced both by SDS-polyacrylamide gel electrophoresis and by the low immune binding, might have masked a conversion process. The combined data show that glucagon is, indeed, synthesized in isolated islets of guinea-pig and mouse, but that this process occurs slowly.

Animals↗
PubMed1980

The retinol-binding protein.

Vitamin A is transported from its storage site in the liver to the epithelial tissues by a carrier protein, the Retinol-binding protein (RBP). In plasma RBP forms a complex with thyroxine-binding prealbumin. The present article reviews available data on the RBP system. The complete primary structure of RBP has been determined. The plasma concentration of RBP is regulated by the vitamin A status so that in vitamin A deficiency RBP molecules are not secreted from the liver. RBP molecules interact with a cell membrane receptor, probably a protein component present on epithelial cells. Vitamin A is thereby delivered to the cells. The uptake of vitamin A by the cells causes a reduction of the affinity of RBP for prealbumin. The RBP molecules which no longer are able to interact efficiently with prealbumin are excreted through the kidney glomerulus and degraded.

Amino Acid Sequence↗
PubMed1979

Nitrogenase from Rhodospirillum rubrum. Relation between 'switch-off' effect and the membrane component. Hydrogen production and acetylene reduction with different nitrogenase component ratios.

Nitrogenase activity of 'membrane-free' extracts, produced from nitrogen-starved Rhodospirillum rubrum to which 4 mM NH4+ had been added is only about 10% of the activity in the control. The activity could be restored to 80% by including the membrane component, earlier found to activate R. rubrum nitrogenase, in the reaction mixture. The relation between this 'switch-off/switch-on' effect and the function of the membrane component is discussed. Hydrogen production catalyzed by R. rubrum nitrogenase is also dependent on activation by the membrane component. Hydrogen production is inhibited by acetylene but the degree of inhibition is dependent on the nitrogenase component ratio. The strongest inhibition is achieved at low MoFe protein/Fe protein rations. The ATP/2E- values are 4-5 at the component ratios giving the highest activity and increase at high MoFe protein/Fe protein ratios. CO inhibits acetylene reduction but has no effect on the hydrogen production.

Acetylene↗
PubMed1979

Aspects of aggression in formerly depressed patients and in healthy controls.

Thirty former inpatients (14 male and 16 female) who had suffered from a nonpsychotic depressive syndrome were investigated by means of a new personality inventory--the KSP--when they had recovered from the depressive disorder, and their results were contrasted to those obtained from 53 healthy controls (19 male, 34 female). Attention was focused on the subscales of the KSP which refer to aspects of aggression. Former patients scored significantly higher than controls in the variables 'irritability,' 'suspicion,' 'guilt,' and 'inhibition of aggression.' The findings suggest a particular personality makeup for at least one subgroup of depression-prone subjects and closely resemble classical concepts of hostility and depression.

Aggression↗
PubMed1979

Salmonella phage glycanases: substrate specificity of the phage P22 endo-rhamnosidase.

Interaction between phage P22 and phenol-water extracted lipopolysaccharides from sensitive Salmonella bacteria belonging to serogroups A, B and Di results in hydrolysis of the alpha-L-rhamnosyl linkages within the tetrasaccharide repeating unit of the O-antigenic polysaccharide chain. These O-antigens have identical structures except for the nature of the 3,6-dideoxy-hexosyl group linked to O-3 of the D-mannosyl residue. Removal of the dideoxysugar, or periodate oxidation followed by borohydride reduction of the L-rhamnosyl residue made the O chain resistant to the endo-rhamnosidase. Substitution of the D-galactosyl residue at O-4, but not at O-6, with an alpha-D-glucosyl group was compatible with hydrolysis. A number of Klebsiella pneumoniae and Shigella flexneri lipo- or capsular polysaccharides containing chain L-rhamnosyl residues were tested but none was sensitive to the P22 endo-rhamnosidase. The substrate specificity of the endo-rhamnosidase parallels the lytic specificity of the phage which suggests that the initial step in phage P22 infection is a P22 tail enzyme O-antigen substrate interaction. The main product of the hydrolysate was octa-, dodeca- and hexadecasaccharides. Treatment of phage FO resistant smooth strains of S. typhimurium with P22 tails removed O polysaccharide chains and made previously 'hidden' FO receptors accessible to the phage.

Glycoside Hydrolases↗
PubMed1979

Variations in self-assessment of personality characteristics in depressed patients, with special reference to aspects of aggression.

30 in-patients, 14 male and 16 female, aged 24-69 years (mean age 47.1 +/- 2.7) suffering from a moderately severe or severe depressive syndrome completed a new personality inventory, the KSP, on two separate occasions. The first-when they were depressed and had just been admitted to the hospital, the second when they were at home and in their customary situation. On the same test occasions the severity of their psychopathology was rated by means of the CPRS. A significant improvement in CPRS rating was ascertained on the second test occasion. In contrast only small changes occurred in the subscales of the KSP. The score referring to 'psychic anxiety' and to 'somatic anxiety' decreased slightly but significantly (p less than 0.05). The scores referring to 'social desirability' also showed a significant (p less than 0.01) slight decrease. Of particular note is that no significant differences were found in the 6 KSP subscales concerned with aspects of aggression, or in the factors which can be obtained from these subscales. Our findings amongst this population of non-psychotic depressed patients do not support the assumption that changes in the direction of aggression occur during depression.

Adult↗
PubMed1978

Properties of the nitrogenase system from a photosynthetic bacterium, Rhodospirillum rubrum.

Soluble nitrogenase from Rhodospirillum rubrum has been isolated and separated into its two components, the MoFe protein and the Fe protein. The MoFe protein has been purified to near homogeneity and has a molecular weight or 215 000. It contains two Mo, 25--30 Fe and 19--22 acid-labile sulphide and consists of four subunits, Mw 56 000. The Fe protein has a molecular weight 65 000. It contains approximately four Fe and four acid-labile sulphide and consists of two subunits, Mw 31 500. The highest specific activities for the purified components are 920 and 1260 nmol ethylene produced per min per mg protein, respectively. The purified components require the membrane component for activity (Nordlund, S., Eriksson, U. and Baltscheffsky, H. (1977) Biochim. Biophys. Acta 462, 187--195). Titration of the MoFe protein with the Fe protein shows saturation and excess MoFe protein over Fe protein is inhibitory. Addition of Fe2+ or Mn2+ to the reaction mixture increases the activity apparently through interaction with the membrane component.

Iron↗
PubMed1977

Necessity of a membrane component for nitrogenase activity in Rhodospirillum rubrum.

Acetylene reduction catalyzed by nitrogenase from Rhodospirillum rubrum has low activity and exhibits a lag phase. The activity can be increased by the addition of a chromatophore membrane component and the lag eliminated by preincubation with this component, which can be solubilized from chromatophores by treatment with NaCl. It is both trypsin- and oxygen-sensitive. Titration of the membrane component with nitrogenase and vice versa shows a saturation point. The membrane component interacts specifically with the Fe protein of nitrogenase, the interaction being ATP- and Mg2+-dependent.

Adenosine Triphosphate↗
PubMed1977

Adsorption of phage P22 to Salmonella typhimurium.

Adsorption of phage P22 to its receptor in the lipopolysaccharide (LPS) of the envelope of Salmonella typhimurium is accompanied by a hydrolytic cleavage of the O polysaccharide chain. The enzyme, and endorhamnosidase, is found in the phage tail. Propagation of a mutant of phage P22, containing two amber mutations, under restrictive conditions permitted isolation of phage tail parts with endorhamnosidase activity. The tail parts, purified by ion exchange chromatography, were shown to be homogenous by polyacrylamide gradient gel electrophoresis, isoelectric focusing in polyacrylamide gel electrophoresis and crossed immunoelectrophoresis. The mol. wt. was estimated to 240000. The optimal pH range for glycosidase activity was 5 to 7 and optimal temperature 37 degrees C. Hydrolysis of the O polysaccharide chain, when estimated with whole bacteria as the substrate, did not seem to be influenced by the cation concentration. Eclipse of P22 phage particles to whole bacteria was likewise uninfluenced by the cation concentration in the reaction mixture, but eclipse by isolated receptor containing LPS required cations. The optimal concentration for divalent cations was 2 X 10(-3) M, for trivalent cations 1 X 10(-3) M.

Adsorption↗