Biomedical subjects

A Andersson

Publications and source records attributed to A Andersson.

At least 73 records · Page 4Linked to original sources

PubMed2000

Engraftment and growth of transplanted pancreatic islets.

Transplantation of pancreatic islets may provide a cure for type 1 diabetes. However, this treatment can currently be offered only to very few patients. To improve transplantation success we need to understand better the mechanisms of how the implanted islets survive, grow and/or maintain adequate function. We herein report on our studies to evaluate the factors responsible for the engraftment, i.e. revascularization, reinnervation etc., of transplanted islets and relate these factors to the metabolism and growth of the islets. Graft metabolism can be monitored by microdialysis probes that allow for the measurement of minute amounts of islet metabolites and hormonal products. Growth of the endocrine cells can be stimulated both in vitro before implantation and in vivo post-transplantation. Another problem is rejection of transplanted islets, which may be overcome by the microencapsulation of islets. The knowledge gained by the present studies will enable us to elucidate the optimal treatment of islets to ensure a maximal survival of the transplanted islets, and may be applied also to clinical islet transplantation.

Animals↗

PubMed2000

Diet, nutrition and diabetes mellitus.

Nutritional management of diabetes mellitus, and the importance of diet in the development of insulin resistance, have for many years been important areas of research and education at the Unit for Clinical Nutrition Research at the Department of Public Health and Caring Sciences (formerly Department of Geriatrics) at Uppsala University. The research has more recently focussed on effects of dietary fat quality in the development of insulin resistance and in treatment of diabetes, on interaction between dietary fat and physical activity in relation to insulin sensitivity and on the importance of carbohydrate rich foods with low glycaemic index in the diabetic diet. Much work has also been directed towards development of educational material about nutrition recommendations and dietary treatment in diabetes mellitus. The ultimate goals for all our efforts are to visualize, and promote, the possibilities and fundamental importance of lifestyle changes. This includes an improved diet and increased physical activity, in the prevention and treatment of diabetes mellitus.

Diabetes Mellitus↗

PubMed2000

Social effects and boar taint: significance for production of slaughter boars (Sus scrofa).

A study was conducted to elucidate the effects of social factors on the concentrations of boar taint substances, androstenone and skatole, in boars. The factors included dominance (social rank) and the effects of strongly tainted animals on other members of the group. Four successive replicates of 100 pigs (50 boars + 50 gilts) with an average live weight of 24 kg were randomly allocated to 10 pens of 10. Data for this study were collected during the period of 67 to 114 kg of live weight and included the repetitive recording of agonistic behavior during competitive feeding; blood sampling for determination of plasma androstenone, skatole and testosterone in boars; feces sampling for determination of skatole content; and collection of bulbourethral glands in boars, and uteri plus ovaries in gilts at slaughter, for the assessment of sexual maturity. Results show an influence of social rank on plasma concentrations of androstenone (P = .0001) and testosterone (P = .0001), the weight of the bulbourethral glands (P = .0001), and plasma skatole (P = .02). Pens were classified according to the pig with the highest concentration of androstenone in the pen into high, medium, and low maximum pens. In pens with high maximum concentrations of androstenone, the second-highest androstenone concentration (P = .0001), and the average concentration (P = .0003) in the pen were higher than those in pens with medium or low maximum concentrations of androstenone. Mean aggression level was also higher (P = .02), but pens with high maximum aggression level did not have higher mean androstenone concentration. Rank effect on androstenone was more important than aggression effect. Neither maximum androstenone concentration nor maximum aggression level in a pen was related to the pen mean stage of sexual maturity in either sex. No influences of rank, aggression, or aggression received were found on the feces skatole level, and no pheromonal communicative function was demonstrated for skatole. High androstenone concentrations did not have a suppressive effect on androstenone concentrations in other males of the group; on the contrary, the levels were increased. This may be due to a stimulating effect of androstenone and, possibly, mating activity. Consequently, in the production of boars for slaughter, strongly tainted animals should be avoided or removed and mating activity minimized. This could be facilitated by, for instance, slaughtering before sexual maturity or separate rearing of the sexes.

Abattoirs↗

PubMed2000

Human islets transplanted to nude mice: in vitro insulin release from retrieved grafts.

Limitations in success of clinical islet transplantation may be coupled to a long-term decline in the secretory capacity of the grafted human islet tissue. To address this issue human or mouse islets were transplanted to the subcapsular space of the kidney of nude mice. After 4 or 12 weeks, the grafts were removed and tested for insulin secretory dynamics in a perifusion system. Insulin secretion of non-transplanted human islets was examined as well. Insulin extracted from 12-week human islet grafts was significantly lower than that from 4-week grafts. Quite in contrast, 12-week mouse islet grafts contained as much insulin as the 4-week grafts. When stimulated with high glucose, insulin secretion was increased by about 6-fold in non-transplanted human islets and 3-fold in 4-week-grafts. The 12-week-grafts were just marginally stimulated by the high glucose stimulation. The mouse islets maintained a 2- to 3-fold insulin response at both time points when challenged high glucose. In non-transplanted human islets glucose-induced insulin secretion was inhibited by noradrenaline, while there was no such effect in the human islet grafts. Addition of acetylcholine potentiated glucose-induced insulin secretion 1-4 fold in both non-transplanted and grafted human islets. When human islet grafts were stimulated by both glucose and caffeine or arginine, insulin secretion was increased severalfold in comparison to glucose stimulation alone. The present results indicate that human islets, in contrast to mouse islets, progressively diminish their insulin content, as well as the capacity to secrete insulin in response to glucose after transplantation into nude mice. Moreover, grafted human islets also lose their responsiveness to the neurotransmittor noradrenaline. These findings may partly explain why clinical islet transplantation so far has met with limited success.

Acetylcholine↗

PubMed1999

[Place of residence determines access to interferon-beta therapy in MS. Less than 15 per cent of patients are treated--big differences between the counties].

Interferon-beta (IFNB) is the first agent to be registered in Sweden for modifying disease course in multiple sclerosis (MS). A nationwide survey uncovered a tenfold variation between counties in the prescribing of IFNB. About 10% of patients received treatment in a few counties, while in most the figure was even smaller. No correlation was found between sales of IFNB and numbers of neurologists in the respective counties. Patients should receive treatment according to national medical guidelines, regardless of place of residence.

Drug Costs↗

PubMed1999

Light-dependent regulation and postnatal development of the interferon-gamma receptor in the rat suprachiasmatic nuclei.

The interferon-gamma receptor gene was detected in the rat hypothalamic suprachiasmatic nuclei (SCN), the main pacemaker for circadian rhythms, and the molecular identity of the transcript was confirmed by sequencing. The expression of the receptor protein showed a daily rhythm that was dependent on light. It reached its adult pattern in the SCN between postnatal day 11 and 20, i.e., at a time when capacity for photic entrainment of the pacemaker is established.

Aging↗

PubMed1999

Transplantation of alginate microcapsules: generation of antibodies against alginates and encapsulated porcine islet-like cell clusters.

BACKGROUND: Microencapsulation of islets of Langherhans in alginate poly-L-lysine capsules provides an effective protection against cell-mediated immune destruction, and ideally should allow the transplantation of islets in the absence of immunosuppression. It has previously been suggested that alginate rich in mannuronic acid (high M) is more immunogenic than alginate rich in guluronic acid (high G). The ability of these alginates to induce an antibody response in the recipient or act as an adjuvant to antibody responses against antigens leaked from the capsule was investigated in the present study. METHODS: Empty capsules made from these different types of alginate were transplanted intraperitoneally to Wistar rats or Balb/c mice. In addition, some animals were also injected with bovine serum albumin to assess the ability of the alginates to act as an adjuvant to this antigen. Antibody responses to intraperitoneally transplanted free and microencapsulated fetal porcine islet like cell clusters (ICC) were also evaluated, in animals treated with or without cyclosporine. RESULTS: Antibodies against high M-alginate capsules were detected in the sera of mice transplanted with this capsule type. However, this response was not seen after the transplantation of high G capsules. When Wistar rats were used as recipients, no antibody responses were detected against any type of alginate capsules. Neither type of capsule acted as an adjuvant. Antibodies against ICC were present, in rats transplanted with both nonencapsulated and encapsulated ICCs. Administration of cyclosporine could abolish this production of antibodies against ICC. CONCLUSIONS: High G-alginate capsules are less immunogenic than high M capsules. Because encapsulation did not protect against the generation of antibodies against ICC, it can be assumed that antigen leakage from the capsules occurs, as no evidence was found for capsules breaking in vivo.

Adjuvants, Immunologic↗

PubMed1999

Comparison between automatic ribotyping and random amplified polymorphic DNA analysis of Bacillus cereus isolates from the dairy industry.

Discrimination by automatic ribotyping and random amplified polymorphic DNA PCR, RAPD, was compared for 40 different B. cereus dairy isolates, 4 different B. mycoides isolates and 6 culture collection strains. RAPD-PCR has previously shown to be useful for tracing contamination routes of B. cereus to milk. Automatic ribotyping using EcoRI and PvuII separated the B. cereus and B. mycoides isolates/strains into 36 different ribotypes. RAPD-typing with primers generated 40 different RAPD-profiles. However, 17 isolates clustered into eight groups, irrespective of the primer and restriction enzyme used, and in all but one case, the isolates with the same pattern were isolated from the same dairy. Automatic ribotyping proved to be a useful, standardized and quick method to discriminate between B. cereus strains, only slightly less discriminatory than RAPD-typing.

Animals↗

PubMed1999

Lack of influence of menstrual cycle and premenstrual syndrome diagnosis on pregnanolone pharmacokinetics.

OBJECTIVE: Pregnanolone is a 3alpha-hydroxylated-5beta-reduced metabolite of the female sex steroid hormone progesterone. The compound is currently being evaluated for anaesthetic purposes. Previous studies have indicated a differential physiological response across the menstrual cycle and a different response in patients with premenstrual syndrome (PMS). This study was undertaken to determine whether hormonal changes during the menstrual cycle influence pregnanolone pharmacokinetics and to compare PMS diagnosis-related differences in pregnanolone pharmacokinetics. METHODS: Seven patients with premenstrual syndrome and seven female controls were given three increasing doses of pregnanolone in the follicular and luteal phase of the menstrual cycle. RESULTS: Mean pregnanolone elimination half-life varied between 28.4 min and 31.8 min and clearance between 59.6 ml x min(-1) x kg(-1) and 64.0 ml x min(-1) x kg(-1), depending on diagnostic group and cycle phase. No significant differences in pregnanolone pharmacokinetic properties were found between PMS patients and controls in either phase of the menstrual cycle. Furthermore, no differences in pharmacokinetic variables were detected between cycle phases. CONCLUSION: Pregnanolone pharmacokinetics do not differ between follicular and luteal phase of the menstrual cycle, nor between PMS patients and control subjects.

Adult↗

PubMed1999

Thiol and redox reactive agents exert different effects on glutathione metabolism in HeLa cell cultures.

Glutathione protects cells against oxidative damage, free radical damage and other types of toxicity. The aim of the present study was to investigate the impact on glutathione metabolism exerted by different thiol or redox reactive agents. Intracellular concentrations of glutathione in HeLa cell cultures were lowered after addition of agents mainly exerting oxidative stress (homocysteine and hydrogen peroxide), whereas thiol reactive oxidative agents (mercury ions, copper ions and hydroquinone) in concentrations not affecting cell growth seemed to stimulate the production of glutathione. Possibly, the thiol reactive agents decrease the concentration of glutathione, thereby stimulating further synthesis of glutathione, since glutathione synthesis is subject to feedback regulation by glutathione on gamma-glutamylcysteine synthase. Redox changes after addition of thiol and redox reactive agents were also investigated. Copper ions lowered the concentrations of reduced forms of all extracellular thiols and of intracellular reduced cysteine in HeLa cell cultures. The addition of mercury ions, hydroquinone, homocysteine or hydrogen peroxide did not change the proportions between reduced and total thiol concentrations. After addition of buthionine sulfoxime, the total concentrations of intra- and extracellular glutathione were markedly decreased and the ratio between reduced and total glutathione concentrations was lowered. However, both cysteine and homocysteine exhibited normal ratios between the concentrations of reduced and total thiols in the presence of buthionine sulfoxime. This finding could be due to other cellular antioxidants, such as thioredoxin, ascorbic acid or tocopherols, maintaining redox status of these thiols.

Antioxidants↗

PubMed1999

Differences in amyloid deposition in islets of transgenic mice expressing human islet amyloid polypeptide versus human islets implanted into nude mice.

Islet amyloid polypeptide (IAPP)-derived amyloid is frequently deposited in the islets of Langerhans in patients with chronic non-insulin-dependent diabetes mellitus (NIDDM). When human islets were implanted under the renal capsule in nude mice, amyloid occurred in 73% of the grafts within 2 weeks. In this study, we compare the deposition of amyloid in islets from a transgenic mouse strain expressing human IAPP (hIAPP) and in normal human islets after implantation in nude mice. The implantations were performed as follows: (1) nondiabetic recipients were given islets from transgenic mice alone, (2) human islets were implanted in the upper pole of the kidney and islets from transgenic mice were implanted in the lower pole of the kidney, (3) grafts containing a mixture of human and transgenic islets were implanted, and (4) transgenic islets and islets from nontransgenic littermates were implanted in therapeutic numbers into recipients made diabetic by a single injection of alloxan prior to implantation. The implants were removed after various periods from 4 days to 8 weeks. The implants were either fixed in Formalin, stained for amyloid, and viewed in polarized light, or processed for immunoelectron microscopy and studied after immunolabeling with specific antibodies against IAPP. We found that the course of amyloid deposition differed significantly between human islets and hIAPP-expressing mouse islets. In human islets, amyloid was mainly deposited intracellularly and only small amounts of amyloid were found extracellularly. In contrast, in islets from transgenic mice, amyloid was exclusively deposited extracellularly and deposition in this site was preceded by an aggregation of immunoreactive material along the basement membrane. These findings point to separate mechanisms for amyloid formation in these two models.

Amyloid↗

PubMed1999

Purification of full-length enterovirus cDNA by solid phase hybridization capture facilitates amplification of complete genomes.

The aim of the study was to develop a method for the selective purification of full-length enterovirus single strand (ss) cDNA for subsequent amplification of complete enterovirus genomes by long distance PCR. As a model system we have used the prototype strain of echovirus 5 (EV5). Due to inefficient first strand cDNA synthesis using EV5 RNA as template, only a few molecules of EV5 sscDNA were completely reverse transcribed and no amplification products were observed when long distance polymerase chain reaction (LD-PCR) was used for amplification of complete EV5 genomes. To purify the complete EV5 cDNA present, an oligonucleotide, derived from the conserved 5' end of an enterovirus genome, was immobilized on paramagnetic beads and complete EV5 sscDNA was captured and purified from the less than full-length cDNAs. LD-PCR using the purified EV5 cDNA resulted in amplification of complete EV5 genomes. Transfection of the EV5 RNA transcribed from these uncloned amplicons resulted in production of replicating viruses. This demonstrates that solid phase hybridization capture of sscDNA is an efficient method that can be used for enrichment and purification of full-length enterovirus sscDNAs.

Cell Line↗

PubMed1999

Echovirus 5: infectious transcripts and complete nucleotide sequence from uncloned cDNA.

Echovirus 5 (EV5) may be isolated from various neurological and exanthematic diseases. To determine the relationship of EV5 to other enteroviruses and for studies of its interactions with the target cell, the complete nucleotide sequence of EV5 was determined. Three overlapping fragments, collectively representing the complete genome, were amplified with RT-PCR and sequenced. Analysis of the EV5 sequence revealed a typical enterovirus-like organization of the genome. To verify that the cDNA generated sequence was derived from infectious viruses, complete EV5 genomes were amplified in one amplicon by long distance PCR. Transfection of in vitro transcribed RNA from these amplicons into cell cultures resulted in replicating EV5. Comparison of the overall nucleotide and amino acid sequences demonstrates that EV5 can be regarded as a coxsackievirus B-like enterovirus. Variable sequences between EV5 and the well characterized coxsackievirus B3 (CVB3) are for the most part observed for amino acid residues that correspond to exposed sequences in the CVB3 capsid. This observation indicates that the reported EV5 strain recently diverged from group B coxsackieviruses.

Amino Acid Sequence↗

PubMed1999

Genomic and phylogenetic characterization of coxsackievirus B2 prototype strain Ohio-1.

The human picornavirus coxsackievirus B2 (CVB2) is often linked to several infections, from mild respiratory diseases to more severe illnesses such as myocarditis. In this study, we report the complete genome sequence of CVB2 prototype strain Ohio-1. The genome sequence was determined from reverse transcribed viral RNA, amplified with long distance PCR and used for non-radioactive sequencing. The full length PCR amplicons were used for in vitro transcription and the obtained cRNA was lipofected onto green monkey kidney cells, in order to confirm that the PCR generated sequence reflects a viable virus RNA. The CVB2 genome sequence shows a typical enterovirus genome organization with a total length of 7411 nucleotides. Phylogenetic analysis, using the CVB2 polyprotein in comparison with other enterovirus polyproteins, clearly shows that CVB2 clusters with the coxsackievirus B-like enteroviruses and is more related to coxsackievirus B4 (CVB4) than any other published CVB serotype. The grouping of CVB2 and CVB4 as one subgroup has earlier been reported in connection with receptor usage and ability to replicate in different cell lines. The exposed viral capsid proteins of CVB2 (VP1-VP3) show high similarity to other CVB proteins, except in regions that are likely to be surface epitopes.

Amino Acid Sequence↗

PubMed1999

Stimulation of adenosine A1 receptors attenuates dopamine D1 receptor-mediated increase of NGFI-A, c-fos and jun-B mRNA levels in the dopamine-denervated striatum and dopamine D1 receptor-mediated turning behaviour.

Adenosine A1 receptors antagonistically and specifically modulate the binding and functional characteristics of dopamine D1 receptors. In the striatum this interaction seems to take place in the GABAergic strionigro-strioentopeduncular neurons, where both receptors are colocalized. D1 receptors in the strionigro-strioentopeduncular neurons are involved in the increased striatal expression of immediate-early genes induced by the systemic administration of psychostimulants and D1 receptor agonists. Previous results suggest that a basal expression of the immediate-early gene c-fos tonically facilitates the functioning of strionigro-strioentopeduncular neurons and facilitates D1 receptor-mediated motor activation. The role of A1 receptors in the modulation of the expression of striatal D1 receptor-regulated immediate-early genes and the D1 receptor-mediated motor activation was investigated in rats with a unilateral lesion of the ascending dopaminergic pathways. The systemic administration of the A1 agonist N6-cyclopentyladenosine (CPA, 0.1 mg/kg) significantly decreased the number of contralateral turns induced by the D1 agonist SKF 38393 (3 mg/kg). Higher doses of CPA (0.5 mg/kg) were necessary to inhibit the turning behaviour induced by the D2 agonist quinpirole (0.1 mg/kg). By using in situ hybridization it was found that CPA (0.1 mg/kg) significantly inhibited the SKF 38393-induced increase in the expression of NGFI-A and c-fos mRNA levels in the dopamine-denervated striatum. The increase in jun-B mRNA expression could only be inhibited with the high dose of CPA (0.5 mg/kg). A stronger effect of the A1 agonist was found in the ventral striatum (nucleus accumbens) compared with the dorsal striatum (dorsolateral caudate-putamen). The results indicate the existence of antagonistic A1-D1 receptor-receptor interactions in the dopamine-denervated striatum controlling D1 receptor transduction at supersensitive D1 receptors.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗

PubMed1999

Lack of effect of acid suppression therapy on gastric atrophy. Nordic Gerd Study Group.

BACKGROUND & AIMS: A hypothesis suggesting that profound acid inhibition therapy facilitates and hastens the development of gastric glandular atrophy in patients infected with Helicobacter pylori was investigated in this randomized study comparing omeprazole therapy with antireflux surgery (ARS) for chronic gastroesophageal reflux disease (GERD). METHODS: Patients with esophagitis and/or chronic GERD were enrolled; 155 patients were randomized to ARS and 155 to long-term omeprazole therapy. Baseline data were obtained and repeated after 3 years in 131 ARS patients and in 139 omeprazole-treated patients. Histopathologic status of the oxyntic mucosa was assessed according to the Sydney system. RESULTS: Forty omeprazole-treated patients were infected with H. pylori compared with 53 in the ARS group. Basal gastrin levels were significantly higher in H. pylori-infected patients, particularly in the omeprazole group. No further increases in serum gastrin levels were observed during 3 years. Despite 3 years of therapy, only slight changes were found in the prevalence of inflammation in the corpus mucosa of H. pylori-infected subjects. A slow progression of gastric glandular atrophy was observed in these patients irrespective of therapy with no obvious difference between treatment regimens. Intestinal metaplasia (all of type I) was only exceptionally observed with no difference between the treatment arms. CONCLUSIONS: Acid-suppressive therapy in the form of omeprazole maintained for 3 years facilitates neither the development of gastric glandular atrophy of the corpus mucosa nor the occurrence of intestinal metaplasia in H. pylori-infected GERD patients.

Adolescent↗

PubMed1999

Beta-cells, oxidative stress, lysosomal stability, and apoptotic/necrotic cell death.

Reactive oxygen intermediates (ROI) may be involved in the destruction of pancreatic beta-cells during the development of insulin-dependent diabetes mellitus (IDDM). To investigate the possible role of lysosomes in this process, normal mouse beta-cells were cultured as monolayers at D-glucose concentrations of 1.6 (pronounced crinophagy), 11 or 28 mM (minimal crinophagy), subjected to a low level of oxidative stress and returned to standard culture conditions. Some cultures were exposed to desferrioxamine (Des) before the oxidative stress. As a result of such stress, many of the cells' lysosomes ruptured with consequent apoptosis or necrosis. Cells kept at 1.6 mM glucose were rich in secretory granules, showed crinophagy/autophagy, were very sensitive to oxidative stress, and had the least stable lysosomes. Cells kept at 28 mM glucose did not show crinophagy, contained fewer secretory granules, were less sensitive to oxidative stress, and had more stable lysosomes. Des-treated cells behaved almost as cells not exposed to oxidative stress at all. The findings suggest that iron may occur together with zinc within the secretory granules and that it sensitizes crinophagic lysosomes to oxidative stress. The stress that was applied in this study may be comparable to what occurs within the vicinity of activated macrophages during autoimmune insulitis.

Animals↗

PubMed1999

Human islets in mixed islet grafts protect mouse pancreatic beta-cells from alloxan toxicity.

We have previously shown that human beta-cells are resistant to the toxic effects of alloxan. In order to further clarify this characteristic of human islets, we investigated whether these cells might transfer their alloxan resistance to alloxan-sensitive rat or mouse islets. Islets from two species (human-mouse or rat-mouse) were mixed into one graft, which was implanted into the subcapsular kidney space of nude mice. Alloxan or saline was injected intravenously two weeks after implantation and one week thereafter the mice were killed. The number of grafted and endogenous beta-cells were evaluated by a semi-quantitative method after immunohistochemistry. Human islet production of the scavenging enzymes extracellular superoxide dismutase and plasma glutathione peroxidase were analyzed with ELISA-techniques, and mouse and human islet hydrogen peroxide breakdown activity were monitored with a horseradish peroxidase-dependent assay. Mouse beta-cells transplanted together with human islets were protected against alloxan cytotoxicity. Rat islets did not protect mouse beta-cells against alloxan, suggesting that the mixing procedure as such did not impose the protection. Production of extracellular superoxide dismutase and plasma glutathione peroxidase by human islets was very low. Moreover, H2O2 breakdown in vitro, did not differ between human and mouse islets. Alloxan-insensitive human islets protect mouse beta-cells against alloxan-induced lesions, suggesting that yet to be identified extracellular factors are involved in human islet resistance to alloxan toxicity.

Alloxan↗