| 51. |
- Karlsson, Sven, et al.
(författare)
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Direct cytoplasmic CA(2+) responses to gastrin-releasing peptide in single beta cells
- 2001
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Ingår i: Biochemical and Biophysical Research Communications. - : Elsevier BV. - 1090-2104 .- 0006-291X. ; 280:3, s. 610-614
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Tidskriftsartikel (refereegranskat)abstract
- The neuropeptide gastrin releasing peptide (GRP) stimulates insulin secretion and induces oscillations of the cytoplasmic Ca(2+) concentration ([Ca(2+)](cyt)) in clonal insulinoma cells. It is not known whether GRP affects [Ca(2+)](cyt) in normal beta cells. We investigated, in single, normal, mouse islet beta cells, the effects of GRP on [Ca(2+)](cyt), by dual wavelength spectrophotofluorometry. Beta cells were identified by their typical response to glucose or tolbutamide. At 15 mM glucose, GRP (100 nM) evoked an immediate [Ca(2+)](cyt) transient to 423 +/- 48 nM compared to 126 +/- 18 nM before GRP (P < 0.001). After the initial transient, [Ca(2+)](cyt) exhibited either a sustained elevation or oscillations. At 3.3 mM glucose, in cells with a non-oscillating [Ca(2+)](cyt), GRP stimulated a prompt increase in [Ca(2+)](cyt) (from 60 +/- 6 to 285 +/- 30 nM, P = 0.024) followed by either a sustained increase in [Ca(2+)](cyt) or [Ca(2+)](cyt) oscillations. We conclude that GRP promptly elevates [Ca(2+)](cyt) by a direct action in normal mouse pancreatic beta cells.
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| 52. |
- Khan, A, et al.
(författare)
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Long-term leptin treatment of ob/ob mice improves glucose-induced insulin secretion
- 2001
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Ingår i: International Journal of Obesity. - : Springer Science and Business Media LLC. - 1476-5497 .- 0307-0565. ; 25:6, s. 816-821
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Previous studies have demonstrated that leptin inhibits glucose-stimulated insulin secretion from isolated islets, although a lack of leptin effect on insulin secretion has also been reported. The effect of long term in vivo leptin treatment of insulin secretion has, however, not been established. Therefore, in the present study, we have evaluated the effect of long term in vivo treatment of leptin on glucose-induced insulin secretion in ob/ob mice. METHODS: After 7 days' treatment of leptin (100 microg daily s.c.), insulin release was measured in isolated islets by batch incubation followed by radioimmunoassay. Glucose utilization and oxidation were measured by measuring the formation of (3)H(2)O and (14)CO(2) from [5-(3)H] and [U-(14)C] glucose, respectively. Glucose-6-phosphatase activity was measured by measuring the conversion of (14)C-glucose-6-P to (14)C-glucose. In addition, immunohistochemistry of pancreatic specimens was undertaken for study of expression of insulin, GLUT-2 and hormone-sensitive lipase (HSL). RESULTS: Leptin treatment significantly improved insulin secretion both at 5.5 mM (by 15%; P<0.05) and 16.7 mM (by 85%; P<0.001) glucose, compared to vehicle-treated controls. Furthermore, whereas leptin treatment did not affect islet insulin or DNA contents, a significant decrease in islet triglyceride content and glucose-6-phosphatase activity was observed. Moreover, the immunocytochemical data revealed an increased immunostaining for insulin, GLUT-2 and hormone-sensitive lipase (HSL) in islets from leptin-treated ob/ob mice. CONCLUSION: The results suggest that long-term leptin treatment of ob/ob mice improves glucose-stimulated insulin secretion in parallel with reduced glucose-6-phosphatase activity, increased HSL and decreased triglyceride levels in islets. These perturbations may explain the improvement of glucose-stimulated insulin secretion induced by leptin.
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| 53. |
- Korsgren, Magnus, et al.
(författare)
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Allergic eosinophil-rich inflammation develops in lungs and airways of B cell-deficient mice
- 1997
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Ingår i: Journal of Experimental Medicine. - 1540-9538. ; 185:5, s. 885-892
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Tidskriftsartikel (refereegranskat)abstract
- Immunoglobulins (Ig), particularly IgE, are believed to be crucially involved in the pathogenesis of asthma and, equally, in allergic models of the disease. To validate this paradigm we examined homozygous mutant C57BL/6 mice, which are B cell deficient, lacking all Ig. Mice were immunized intraperitoneally with 10 micrograms ovalbumin (OVA) plus alum, followed by daily (day 14-20) 30 min exposures to OVA aerosol (OVA/OVA group). Three control groups were run: OVA intraperitoneally plus saline (SAL) aerosol (OVA/SAL group); saline intraperitoneally plus saline aerosol; saline intraperitoneally plus OVA aerosol (n = 6-7). Lung and large airway tissues obtained 24 h after the last OVA or SAL exposure were examined by light microscopy and transmission electron microscopy (TEM). The Ig-deficient mice receiving OVA/ OVA treatment had swollen and discolored lungs and exhibited marked eosinophilia both in large airway subepithelial tissue (49.2 +/- 12.0 cells/mm basement membrane [BM] versus OVA/ SAL control 1.2 +/- 0.3 cells/mm BM; P < 0.001), and perivascularly and peribronchially in the lung (49.3 +/- 9.0 cells/unit area versus OVA/SAL control 2.6 +/- 0.6 cells/unit area; P < 0.001). The eosinophilia extended to the regional lymph nodes. TEM confirmed the subepithelial and perivascular localization of eosinophils. Mucus cells in large airway epithelium increased from 1.5 +/- 0.8 (OVA/SAL mice) to 39.5 +/- 5.7 cells/mm BM in OVA/OVA treated mice (P < 0.001). OVA/SAL mice never differed from the other control groups. Corresponding experiments in wild-type mice (n = 6-7 in each group) showed qualitatively similar but less pronounced eosinophil and mucus cell changes. Macrophages and CD4+ T cells increased in lungs of all OVA/OVA-treated mice. Mast cell number did not differ but degranulation was detected only in OVA/OVA-treated wild-type mice. Immunization to OVA followed by OVA challenges thus cause eosinophil-rich inflammation in airways and lungs of mice without involvement of B cells and Ig.
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| 54. |
- Korsgren, Magnus, et al.
(författare)
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Lack of systemic anaphylaxis and aeroallergen-induced airway plasma extravasation in allergic immunoglobulin-deficient mice
- 1999
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Ingår i: International Archives of Allergy and Immunology. - : S. Karger AG. - 1423-0097 .- 1018-2438. ; 118:1, s. 67-73
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: In Ig-deficient mice allergen challenge-induced pulmonary late phase inflammation is at least as pronounced as in wild-type animals. This study investigates immediate hypersensitivity responses in these mice. METHODS: To examine the acute plasma extravasation response in airway tissue, immunized Ig-deficient and wild-type mice and sham-immunized wild-type controls were subjected to 15 min ovalbumin aerosol challenge. 125I-albumin was injected (i.v.) 1 min prior to challenge. Immediately after challenge 131I-albumin was injected and the experiment was terminated. Plasma and trachea were analyzed for 125I and 131I, and the amount of extravasated plasma in the trachea was calculated. To study the development of systemic anaphylaxis immunized Ig-deficient and wild-type animals received intravenous allergen challenge followed by determination of mast cell responses and plasma histamine levels. RESULTS: Allergen aerosol-exposed immunized wild-type mice exhibited marked plasma extravasation in the trachea (pd0.01 vs. wild-type controls), but in the corresponding Ig-deficient mice there was no increased extravasation. Immunized Ig-deficient mice receiving intravenous allergen challenge were resistant to anaphylactic shock. By contrast, the wild-type animals developed systemic anaphylaxis, accompanied by plasma extravasation, mast cell degranulation, elevated plasma histamine and rapid death. CONCLUSION: The present data are evidence that immunoglobulins are crucial for the development of immediate (type 1) responses. These findings together with our previous observations on late-phase pulmonary responses suggest that immediate hypersensitivity processes are unimportant for development of the late phase inflammation in the respiratory tract of mice.
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| 55. |
- Korsgren, Magnus, et al.
(författare)
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Neural expression and increased lavage fluid levels of secretoneurin in seasonal allergic rhinitis.
- 2003
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Ingår i: American Journal of Respiratory and Critical Care Medicine. - 1535-4970. ; 167:11, s. 1504-1508
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Tidskriftsartikel (refereegranskat)abstract
- Secretoneurin is a neuropeptide potentially involved in migration of eosinophils, monocytes, and dendritic cells. Whether secretoneurin is present in the human airway mucosa and whether it is released at ongoing allergic airway inflammation is currently unknown. In patients with allergic rhinitis, we have explored the occurrence of secretoneurin in nasal mucosal biopsies and lavage fluids before and during natural allergen exposure. Immunohistochemical analysis revealed an abundance of nerves displaying secretoneurin immunoreactivity, which were distributed predominantly around blood vessels and submucosal glands. A majority of nerve fibers containing vesicular acetylcholine transporter, tyrosine hydroxylase, calcitonin gene–related peptide, and vasoactive intestinal peptide were also secretoneurin-immunoreactive, indicating a localization of secretoneurin in cholinergic, adrenergic, and sensory nerves. Lavage fluid levels of secretoneurin were increased at allergen exposure (p < 0.01–0.05). Levels of secretoneurin did not correlate with eosinophil cationic protein ({rho} = 0.1, p = 0.7). We conclude that secretoneurin has a widespread occurrence in nasal mucosal nerves of patients with seasonal allergic rhinitis and that increased nasal lavage fluid levels of secretoneurin may characterize ongoing allergen exposure. These data favor a role of secretoneurin in the local traffic of immune cells in human airway mucosa.
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| 56. |
- Korsgren, Magnus, et al.
(författare)
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Role of macrophage migration inhibitory factor (MIF) in allergic and endotoxin-induced airway inflammation in mice
- 2000
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Ingår i: Mediators of Inflammation. - : Hindawi Limited. - 0962-9351 .- 1466-1861. ; 9:1, s. 15-23
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Tidskriftsartikel (refereegranskat)abstract
- Macrophage migration inhibitory factor (MIF) has recently been forwarded as a critical regulator of inflammatory conditions, and it has been hypothesized that MIF may have a role in the pathogenesis of asthma and chronic obstructive pulmonary disease (COPD). Hence, we examined effects of MIF immunoneutralization on the development of allergen-induced eosinophilic inflammation as well as on lipopolysaccharide (LPS)-induced neutrophilic inflammation in lungs of mice. Anti-MIF serum validated with respect to MIF neutralizing capacity or normal rabbit serum (NRS) was administered i.p. repeatedly during allergen aerosol exposure of ovalbumin (OVA)-immunized mice in an established model of allergic asthma, or once before instillation of a minimal dose of LPS into the airways of mice, a tentative model of COPD. Anti-MIF treatment did not affect the induced lung tissue eosinophilia or the cellular composition of bronchoalveolar lavage fluid (BALF) in the asthma model. Likewise, anti-MIF treatment did not affect the LPS-induced neutrophilia in lung tissue, BALF, or blood, nor did it reduce BALF levels of tumor necrosis factor-alpha (TNF-alpha) and macrophage inflammatory protein-1alpha (MIP-1alpha). The present data suggest that MIF is not critically important for allergen-induced eosinophilic, and LPS-induced neutrophilic responses in lungs of mice. These findings do not support a role of MIF inhibition in the treatment of inflammatory respiratory diseases.
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| 57. |
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| 58. |
- Korsgren, Olle, et al.
(författare)
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Reinnervation of syngeneic pancreatico-duodenal grafts in rats
- 2001
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Ingår i: Transplantation. - 1534-6080. ; 71:1, s. 8-13
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Knowledge on the reinnervation of transplanted organs is scarce, and the aim of the study was therefore to evaluate to what degree syngeneic pancreas grafts were reinnervated in rats. METHODS: Syngeneic pancreatico-duodenal transplantations were performed in normoglycemic Wistar-Furth rats. Native and transplanted pancreas and duodenum were removed 4 or 40 weeks after implantation, and processed for indirect immunofluorescence using antibodies directed against vasoactive intestinal peptide, substance P (SP), calcitonin gene-related peptide (CGRP), neuropeptide Y (NPY), tyrosine hydroxylase (TH), or the general neuronal marker protein gene product 9.5. RESULTS: Four weeks after transplantation a moderate to rich number of protein gene product 9.5-positive nerve fibers were found homogeneously distributed through the pancreas, probably representing the intrapancreatic nervous system, because the grafted pancreas lacked both a sympathetic (TH/NPY) and sensory (SP/CGRP) innervation 4 weeks after implantation. In a few of the animals there was a marked increase in SP-immunoreactive nerves (lacking CGRP), most conspicuous in the duodenal portion, both 4 and 40 weeks after transplantation probably secondary to a chronic pancreatitis. The fibers seemed to emanate from intrapancreatic ganglia and possibly also from enteric neurons in adjacent parts of the duodenum. A few scattered vasoactive intestinal peptide-containing nerve fibers probably also emanating from local ganglia could be seen throughout the grafted pancreas both 4 and 40 weeks after transplantation. At 40 weeks after transplantation sympathetic (TH- and NPY-positive) nerve fibers were regularly seen, whereas CGRP-positive nerve fibers were still virtually lacking in the pancreas. To trace the origin of the ingrowing nerve fibers, the tracer True Blue was injected into the grafted pancreas of some rats 38 weeks after transplantation, i.e., 2 weeks before killing. True Blue-labeled nerve cell bodies were numerous in the celiac ganglion (presumably sympathetic nerves) and few in dorsal root ganglia (sensory nerves). CONCLUSIONS: The data suggest that the transplanted rat pancreas becomes reinnervated by mainly sympathetic nerve fibers.
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| 59. |
- Kvist Reimer, Martina, et al.
(författare)
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Effects of chemical sympathectomy by means of 6-hydroxydopamine on insulin secretion and islet morphology in alloxan-diabetic mice.
- 2002
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Ingår i: Cell and Tissue Research. - : Springer Science and Business Media LLC. - 1432-0878 .- 0302-766X. ; 307:2, s. 203-209
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Tidskriftsartikel (refereegranskat)abstract
- Abstract. Activation of sympathetic nerves increases circulating glucose and inhibits insulin release from the islet beta-cells, which might contribute to stress-related diabetes. Accordingly, we have shown previously that blockade of parasympathetic activity aggravates diabetes in alloxan-treated mice, suggesting that unopposed sympathetic activity impairs diabetes. In this study, we tested whether elimination of sympathetic nerve activity by chemical sympathectomy with 6-hydroxydopamine (6-OHDA; 60 mg/kg) ameliorates the diabetogenic effects of alloxan (50 mg/kg) in NMRI mice. Mice given alloxan alone developed manifest diabetes after 2 days, as indicated by hyperglycemia. The diabetes persisted throughout the 35-day study period. Pretreatment with 6-OHDA did not, however, affect the glucose levels or the low, 2-min in vivo insulin response to glucose (1 g/kg) after alloxan. In situ hybridization at day 35 revealed a significantly reduced grain area of insulin-mRNA in the alloxan-treated animals, which was not affected by 6-OHDA, and an altered islet architecture, with accumulation of glucagon cells in the central portion. Also 6-OHDA alone reduced the insulin mRNA area, but this was accompanied by an increase in the total islet area. We conclude that, in contrast to cholinergic inhibition, sympathectomy does not perturb the development of chemically induced diabetes in mice. Alone, however, sympathectomy reduces insulin gene expression and induces increased islet size, suggesting that sympathetic nerves are of importance for long-term islet function.
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| 60. |
- Kvist Reimer, Martina, et al.
(författare)
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Local growth factors are beneficial for the autonomic reinnervation of transplanted islets in rats
- 2003
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Ingår i: Pancreas. - 0885-3177. ; 26:4, s. 392-397
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Transplanted islets, being avascular and denervated, receive blood vessels and nerves from the recipient. Reinnervation may account in part for the normalization of islet function in islet transplants. Whether reinnervation is possible to augment is not known. Aims and Methodology: To explore whether reinnervation of transplanted islets is augmented by local addition of growth factors to the graft, syngeneic islets were transplanted to the pancreas of streptozotocin-diabetic Lewis rats with or without pellets locally releasing nerve growth factor (NGF) and vascular endothelial growth factor (VEGF), alone or in combination. The pellets released growth factors for 14 days at a rate of 20 ng/day. After 7 weeks, pancreatic tissue was processed for immunofluorescence of insulin and the neural markers neuropeptide Y (NPY) and tyrosine hydroxylase (TH). Results: Islets were larger and more numerous after treatment with NGF (p = 0.024) and with NGF in combination with VEGF (p = 0.044). Similarly, immunostaining for TH and the C-terminal flanking peptide of NPY (C-PON) was more pronounced after treatment with NGF in combination with VEGF than in controls (both p < 0.05). Conclusion: Local growth factor treatment has a beneficial effect on autonomic reinnervation as well as islet integrity and survival of the graft after islet transplantation in rats.
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