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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Inflammation research 8 (1978), S. 380-381 
    ISSN: 1420-908X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Conclusion It appears that the rapid method elaborated byOkuyama andKobayashi |2| is not well suited as a measure of diamine oxidase activity in tissues.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0428
    Keywords: Tissue culture ; pancreatic islets ; degranulation ; endoplasmic reticulum ; insulin content ; insulin release ; insulin degradation ; insulin biosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Isolated mouse pancreatic islets were maintained in tissue culture for up to 12 days in glucose concentrations varying between 3.3 and 28 ml. A satisfactory ultrastructural preservation of the islet cells was found irrespective of the glucose concentration of the culture medium. While the B-cells of islets cultured in the lower glucose concentration showed slight degranulation, there was extensive degranulation and increased amounts of rough-surfaced endoplasmic reticulum after culture in the higher glucose concentration. The immunoreactive insulin content of islets cultured at 28 mM glucose was markedly decreased and the insulin secretion during the culture period was much higher than that of islets cultured at 3.3 mM glucose. The insulin biosynthesis, as reflected in the incorporation of3H-leucine into gel chromatographed extracts of acid-ethanol soluble islet proteins, was studied either during the culture period or at the end of a 6-day culture in short-term incubations lasting for 90 or 180 min. The results consistently showed that the biosynthesis of insulin proceeded at a high rate and remained regulated by glucose throughout the culture period. The continuous addition of newly synthesized and labelled insulin to the small intracellular insulin pool of the high-glucose cultured B-cells produced a very high specific radioactivity of the insulin.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0428
    Keywords: Pancreatic islets ; tissue culture ; calf serum ; culture media ; insulin secretion ; insulin content ; insulin biosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Various conditions for tissue culture of collagenase-isolated mouse pancreatic islets were studied in an attempt to optimize the maintenance of glucose stimulated insulin biosynthesis and release in the cultured specimens. Islets which had been cultured at a physiological glucose concentration (5.5 mmol/l) in the absence of serum had an impaired glucose-stimulated insulin biosynthesis and release as well as a reduced insulin content. Thus, insulin biosynthesis was three times higher after culture in a serum supplemented medium. Further, the insulin secretion of islets cultured in the presence of serum was markedly enhanced in acute incubations with high concentrations of glucose. This response was most pronounced in islets which had been cultured free-floating. A comparison between different culture media showed that islets cultured in RPMI 1640 had the highest insulin production. The present data suggest that the most favourable conditions for long-term storage of isolated islets in culture may be obtained when the islets are maintained as free-floating explants in a culture medium consisting of RPMI 1640 supplemented with serum.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0428
    Keywords: Obese-hyperglycaemic mice ; isolated pancreatic islets ; islet transplantation ; serum glucose ; islet volume ; autoradiography ; islet cell replication ; immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 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.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0428
    Keywords: Obese-hyperglycaemic mice kwalloxan diabetes ; intrasplenic islet transplantation ; islet volume ; serum glucose ; serum insulin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We reported recently that intrasplenic transplantation of syngeneic pancreatic islets failed to cure obese-hyperglycaemic mice, despite a considerable growth of the grafted islets. In the present study, the role of sustained hyperglycaemia and hyperinsulinaemia for regeneration of transplanted islet cells was evaluated in these animals. Islets implanted into alloxan-diabetic C57BL/6J mice in numbers insufficient to restore normoglycaemia did not grow. There was, however, a statistically significant correlation between the mean volume of implanted islets and the degree of normalization of hyperglycaemia. Insulin treatment of these suboptimally islet-implanted C57BL/6J mice resulted in a volume increase of the implanted islets. When corresponding experiments were undertaken with alloxan-diabetic C57BL/KsJ mice, no effect was noted on hyperglycaemia and there was a drastic decrease in the volume of implanted islets. Islets implanted into old obese-hyperglycaemic mice that had returned to normoglycaemia but still were hyperinsulinaemic, decreased markedly in size. The present data suggest that neither hyperglycaemia nor hyperinsulinaemia per se are primarily responsible for the growth of islets in obese-hyperglycaemic mice. Furthermore, it is obvious that the genetic background is very important for morphological and functional responses of the islets to a prolonged period of hyperglycaemic stress.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0428
    Keywords: Pancreatic islets ; tissue culture ; ultrastructure ; morphometry ; mitochondria ; L-leucine ; B-cell function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This study was performed to evaluate whether L-leucine is able to relieve the structural and functional alterations previously described in pancreatic islets exposed in vitro for a prolonged time to a subnormal glucose concentration (3.3 mM). It was found that both the impairment of secretion and the decreased rate of biosynthesis of insulin characteristic, of islets cultured for one week in 3.3 mM glucose were prevented by adding 15 mM L-leucine to the culture medium. Furthermore, the rates of tritiated water production and glucose or leucine oxidation were significantly enhanced after culture in the presence of L-leucine. The rate of DNA synthesis as estimated by the incorporation of tritiated thymidine was, however, unchanged by the presence of L-leucine in the culture medium. Leucine cultured islet cells displayed ultrastructural signs of high functional activity. A detailed morphometric examination revealed fewer but hypertrophic mitochondria. The present results suggest that L-leucine can replace glucose in several respects as a long-term stimulus of the pancreatic B-cells, possibly by acting as a metabolic substrate.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-0428
    Keywords: Human pancreatic islets ; tissue culture ; beta cell function ; islet storage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Islets of Langerhans were isolated from four human kidney donors, aged 16 to 21 years, by the collagenase method described for isolation of rodent islets. So far the human islets have been kept in tissue culture, without attachment, in medium RPMI 1640 supplemented with 10% calf serum for more than 9 months, with preservation of the ability to release insulin in response to glucose stimulation. Replacement of calf serum with serum from normal human subjects did not affect B-cell survival, but resulted in elevated insulin values partly due to lower insulin degrading activity. Thus the described technique presents a valuable tool for studying chronic effects of metabolites and hormones on islet function, as well as for islet storage prior to transplantation into humans.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-0428
    Keywords: Pancreatic islets ; tissue culture ; diabetic serum ; beta-cell function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Islets of Langerhans from NMRI-mice were kept for one week in tissue culture in medium supplemented with human serum obtained from either normal healthy subjects or newly diagnosed juvenile diabetic patients before insulin treatment. Islets cultured in diabetic serum released more insu lin than islets cultured in normal serum, whether tissue culture medium 199 with 5.5–8.3 mmol/l glucose and 10% serum, or culture medium RPMI 1640 with 11 mmol/l glucose and 0.5% serum were used. Islets kept for one week in culture with diabetic serum did not show any decrease in DNA content or glucose induced insulin secretion and biosynthesis. It is concluded that serum from newly diagnosed insulin-dependent diabetic patients stimulates insulin release from isolated mouse islets kept in tissue culture. The underlying mechanism is unknown.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Inflammation research 9 (1979), S. 44-45 
    ISSN: 1420-908X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-0428
    Keywords: Islet β cell ; cyclosporin A mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In the light of recent attempts to treat newly-diagnosed Type 1 (insulin-dependent) diabetic patients with cyclosporin A, and reports suggesting an impaired glucose tolerance following immunosuppresion therapy with cyclosporin A, we investigated the long-term effects of cyclosporin A on islet β-cell morphology and function in vitro. Collagenase-isolated mouse pancreatic islets were cultured free-floating for 7 days in medium RPMI 1640 + 10% calf serum in the presence of cyclosporin A (0.1 or 1.0 mg/l). Islets cultured in the presence of the higher cyclosporin A concentration had impaired islet proinsulin biosynthesis and insulin release when challenged with high glucose concentration. Moreover, the insulin content of the drug-exposed islets was decreased and so was the rate of DNA synthesis. The glucose oxidation and respiratory rates, however, remained unaffected, suggesting that the impaired insulin production was not a result of defective oxidative metabolism. There were no changes in the ultrastructure or phospholipid biosynthesis of the islets after the drug treatment. These data indicate that cyclosporin A affects islets in culture, the clinical implications of which are so far difficult to assess. The inhibitory effect of cyclosporin A on islet cell DNA synthesis must nevertheless be considered in attempts to ameliorate Type 1 (insulin-dependent) diabetes, and when grafting islet cells in numbers primarily insufficient to cure the recipient.
    Type of Medium: Electronic Resource
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