Combined pancreas and kidney transplantation normalizes protein metabolism in insulin-dependent diabetic-uremic patients.
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In order to assess the combined and separate effects of pancreas and kidney transplant on whole-body protein metabolism, 9 insulin-dependent diabetic-uremic patients (IDDUP), 14 patients after combined kidney-pancreas transplantation (KP-Tx), and 6 insulin-dependent diabetic patients with isolated kidney transplant (K-Tx), were studied in the basal postabsorptive state and during euglycemic hyperinsulinemia (study 1). [1-14C]Leucine infusion and indirect calorimetry were utilized to assess leucine metabolism. The subjects were studied again with a combined infusion of insulin and amino acids, given to mimic postprandial amino acid levels (study 2). In the basal state, IDDUP demonstrated with respect to normal subjects (CON): (a) higher free-insulin concentration (17.8 +/- 2.8 vs. 6.8 +/- 1.1 microU/ml, P < 0.01) (107 +/- 17 vs. 41 +/- 7 pM); (b) reduced plasma leucine (92 +/- 9 vs. 124 +/- 2 microM, P < 0.05), branched chain amino acids (BCAA) (297 +/- 34 vs. 416 +/- 10 microM, P < 0.05), endogenous leucine flux (ELF) (28.7 +/- 0.8 vs. 39.5 +/- 0.7 mumol.m-2.min-1, P < 0.01) and nonoxidative leucine disposal (NOLD) (20.7 +/- 0.2 vs. 32.0 +/- 0.7 mumol.m-2. min-1, P < 0.01); (c) similar leucine oxidation (LO) (8.0 +/- 0.1 vs. 7.5 +/- 0.1 mumol.m-2.min-1; P = NS). Both KP-Tx and K-Tx patients showed a complete normalization of plasma leucine (116 +/- 5 and 107 +/- 9 microM), ELF (38.1 +/- 0.1 and 38.5 +/- 0.9 mumol.m-2.min-1), and NOLD (28.3 +/- 0.6 and 31.0 +/- 1.3 mumol.m-2.min-1) (P = NS vs, CON). During hyperinsulinemia (study 1), IDDUP showed a defective decrease of leucine (42% vs. 53%; P < 0.05), BCAA (38% vs. 47%, P < 0.05), ELF (28% vs. 33%, P < 0.05), and LO (0% vs. 32%, P < 0.05) with respect to CON. Isolated kidney transplant reverted the defective inhibition of ELF (34%, P = NS vs. CON) of IDDUP, but not the inhibition of LO (18%, P < 0.05 vs. CON) by insulin. Combined kidney and pancreas transplanation normalized all kinetic parameters of insulin-mediated protein turnover. During combined hyperinsulinemia and hyperaminoacidemia (study 2), IDDUP showed a defective stimulation of NOLD (27.9 +/- 0.7 vs. 36.1 +/- 0.8 mumol.m-2.min-1, P < 0.01 compared to CON), which was normalized by transplantation (44.3 +/- 0.8 mumol.m-2.min-1). (+info)
Concanavalin A-induced posterior subcapsular cataract: a new model of cataractogenesis.
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PURPOSE: To evaluate the effect of Concanavalin A (Con A) on cataract formation in New Zealand Albino rabbits. Uveitis is a chronic inflammatory condition of the eye involving the anterior and/or posterior segments. It may be acute or chronic and is associated with the development of posterior subscapular cataract over time. Con A is a nonspecific inflammatory agent and mitogen for T cells and some B cells. Used extensively in immunogenic studies Con A has been shown to induce uveitis after intravitreal injection in New Zealand Albino rabbits. METHODS: In two separate studies, Con A was injected intracamerally or intravitreally into one eye of 12 New Zealand Albino rabbits and an equal volume of balanced salt solution was injected into the opposite eye as a control. In a third study, the effect of topical steroids after intravitreal injection of Con A was evaluated. In all studies, anterior and posterior inflammation and the development of cataract was monitored by slit lamp biomicroscopy and photography. Cataract formation was also studied histopathologically. RESULTS: Initially, all eyes treated with Con A demonstrated moderate anterior chamber inflammation while eyes treated with balanced salt solution showed no inflammation. Three months after treatment, posterior subcapsular cataracts were present in all rabbit eyes treated with intravitreal Con A. In the third study, topical steroid treatment of Con A-induced inflammation significantly reduced anterior chamber inflammation but had no effect on vitreous humor and posterior subcapsular cataract formation. CONCLUSION: This experimental model was the first to demonstrate the development of posterior subcapsular cataracts after Con-A induced inflammation. The cataract was clinically and histologically similar to human posterior subscapular cataracts. (+info)
Role of retinal pigment epithelium in the development of experimental autoimmune uveitis.
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PURPOSE: To determine the role of retinal pigment epithelium in the induction of S-antigen-induced uveitis by administration of sodium iodate (NaIO3) to selectively damage the retinal pigment epithelium. METHODS: Forty-four Lewis rats were injected with 60 micrograms of S antigen in complete Freund's adjuvant. On postimmunization day 9 the rats were separated into four groups: three groups received NaIO3 at doses of 50, 25, and 10 mg/kg body weight, respectively, and the fourth group (control) received diluent. In addition, separate groups of animals (three in each group) received various doses of NaIO3 or diluent. All of the animals were killed on day 6 after NaIO3 injection, and the eyes were enucleated and submitted for light and electron microscopic examination. In addition, two groups of Lewis rats (6 in each group) were immunized with 0.5 ml of guinea pig spinal cord homogenate in complete Freund's adjuvant to induce experimental allergic encephalomyelitis. On postimmunization day 7, one group received NaIO3 at a dose of 50 mg/kg body weight, whereas the other group received diluent. All animals were killed between days 12 and 14, and spinal cord sections were obtained for microscopic examination. RESULTS: In the control group immunized with S antigen, severe (2+ to 4+) uveoretinitis developed in 70% of the animals. In contrast, only 18% of the animals injected with NaIO3 at a dose of 50 mg/kg body weight exhibited disease, and this was a mild (1+) form. The groups injected with 25 mg/kg (1+ to 2+) and with 10 mg/kg (2+ to 3+) of NaIO3 showed a mild to moderate degree of uveoretinitis in 27% and 50% of the animals, respectively. In the remainder of the animals there was no evidence of uveoretinitis. All of the NaIO3-treated animals showed selective necrosis of the retinal pigment epithelium; this was extensive in the higher dose group and focal in the lower dose groups. In the experimental allergic encephalomyelitis model there was no significant difference in incidence or histologic appearance of demyelinating disease in NaIO3- vs diluent-treated groups. CONCLUSIONS: These results indicate that the retinal pigment epithelium may play a role in the initiation and perpetuation of uveitis after sensitization with S antigen. The effect of NaIO3 appears to be localized to the retinal pigment epithelium; it had no effect on immune reactive cells, as evidenced by the development of experimental allergic encephalomyelitis in animals treated with NaIO3. (+info)
Inhibition of crystallins-induced inflammation in rabbit eyes with five phytogenic compounds.
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Ocular inflammation was induced by injection of crystallins (lens protein) intracamerally and endotoxin intravitreously into rabbit and rat eyes, respectively, and was measured with fluorophotometry by quantitating the amount of fluorescein which entered into the globe. Five compounds isolated from anti-inflammatory Chinese herbs were studied for their effects on ocular inflammation. It was found that lens protein-induced inflammation was inhibited significantly by the topical instillation of pulegone (0.5%), friedelin (0.5%), and sabinene (1%), but not by dihydrojasmon or naringin at concentrations up to 1%. However, none of these compounds inhibited endotoxin-induced posterior uveitis. (+info)
Resident and infiltrating immune cells in the uveal tract in the early and late stages of experimental autoimmune uveoretinitis.
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PURPOSE: To investigate the dynamics of resident and infiltrating immune cells in the choroid and iris during the early and late stages of experimental autoimmune uveitis (EAU) in Lewis rats. METHODS: Uveoretinitis was induced by footpad injection of crude retinal extract and complete Freund's adjuvant with concurrent intraperitoneal injection of Bordetella pertussis. Five experimental (EAU) and five control animals (adjuvant alone) were studied at days 5, 7, 9, 11 (prodromal stage) and 42 (late stage) after immunization. Five normal animals and five animals injected with B. pertussis alone served as further controls. Immunohistochemical localization of resident macrophages, major histocompatibility complex class II (Ia)+ dendritic cells (DC), infiltrating mononuclear cells, and T cells was performed on wholemounts of isolated choroidal and iris tissue. RESULTS: Double immunolabeling confirmed the presence of distinct networks of macrophages (591 +/- 52 cells/mm2) and DC (746 +/- 38 cells/mm2) in the rat choroid. No marked qualitative and quantitative changes were observed in the density or morphologic appearance of ED2+ resident tissue macrophages in the choroid and iris before clinical onset of ocular disease. On day 11, infiltration of ED1+ monocytes had occurred in the iris but not in the choroid; however, marked infiltration of T cells was evident in both choroid (286 +/- 161 cells/mm2) and iris (196 +/- 72 cells/mm2). The total density of Ia+ cells was significantly elevated in the choroid (1152 +/- 192 cells/mm2) at day 11, and small, round Ia+ cells were two to three times more frequent than normal at both sites. The density of T cells and Ia+ cells remained significantly elevated in the choroid and iris in the late stages of EAU. CONCLUSIONS: These data suggest resident uveal tract macrophages undergo no significant alteration in density in the early stages of EAU and that the earliest site of mononuclear cellular infiltrate in EAU occurs in the iris. The increased total density of Ia+ cells in the choroid on day 11 and the presence of significantly increased numbers of small, round Ia+ cells in the iris and choroid may represent increased trafficking of DC in the eye during uveoretinitis. Furthermore, the raised numbers of Ia+ cells, concurrent with the influx of T cells, suggests Ia+ DC and macrophages may act as local antigen-presenting cells in the induction of uveoretinitis. (+info)
Anti-tumor necrosis factor alpha therapy suppresses the induction of experimental autoimmune uveoretinitis in mice by inhibiting antigen priming.
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PURPOSE: Experimental autoimmune uveoretinitis (EAU) serves as a model for several immune-mediated diseases that affect the eye in humans. Previous studies indicated that tumor necrosis factor alpha (TNF-alpha) has an important proinflammatory role in EAU and possibly in human uveitis. In this study, the authors investigated the effect of anti-TNF-alpha therapy on EAU in mice. METHODS: Experimental autoimmune uveoretinitis was induced in B10.A mice by immunization with interphotoreceptor retinoid-binding protein (IRBP). The mice were treated with 100 or 300 microliters rabbit antiserum or polyclonal antibodies to human TNF-alpha. The treatment spanned either the afferent or the efferent stage of EAU (days -1, 1, 3, 5, 7, or days 8, 10, 12, 14, 16, respectively). Control animals were injected with preimmune rabbit serum at the corresponding times or were not treated. Three weeks after immunization, EAU was assessed by clinical evaluation and by histopathology. Immunologic responses were assessed by delayed-type hypersensitivity (DTH), lymphocyte proliferation to IRBP, and relative abundance of IRBP-primed splenocytes. RESULTS: The treatment with rabbit anti-TNF-alpha serum significantly ameliorated disease when given during the afferent stage but had no effect when given during the efferent stage of EAU. The effect on DTH, lymphocyte proliferation, and abundance of antigen-reactive cells roughly paralleled the effect on disease. CONCLUSIONS: Neutralization of systemic TNF ameliorates EAU. The effectiveness of afferent treatment in comparison to the treatment during the efferent stage, together with the reduced proliferation and the reduced abundance of IRBP-responsive cells, suggest that interference with afferent-acting processes such as antigen priming is important to achieve protection from EAU by anti-TNF treatment. (+info)
In vivo quantification of leukocyte behavior in the retina during endotoxin-induced uveitis.
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PURPOSE: The interaction between leukocytes and vascular endothelial cells plays an important role in various inflammatory disorders. This study evaluated leukocyte behavior in the retina during endotoxin-induced uveitis (EIU) in vivo. METHODS: EIU was induced in female Lewis rats by footpad injection of lipopolysaccharide (LPS). The time-course changes of retinal leukocyte behavior were followed at 1.5, 3, 4.5, 6, 12, 24, 48, 72, and 120 hours after LPS treatment using acridine orange digital fluorography, consisting of high-resolution images from a scanning laser ophthalmoscope and a fluorescent nuclear dye of acridine orange. RESULTS: Major retinal vessels were significantly dilated (P < 0.05) at 4.5 hours after LPS injection. The vasodilation, marked in veins, became maximum at 24 hours and subsided at 72 hours. Leukocytes were observed rolling along the walls of major veins at 4.5 hours. The number of rolling leukocytes gradually increased and reached a peak level of 33.8 +/- 3.4 cells/minute per major vein at 12 hours. Leukocyte rolling was still observed at 72 hours. No rolling of leukocytes was observed along the arterial walls throughout any experiments. The velocities of rolling leukocytes were determined at 6, 12, 24, and 48 hours. The leukocyte rolling velocity at 6 hours was significantly slower (33.3 +/- 2.8 microns/second, P < 0.05) than at the other three times (average, 46.6 microns/second). Cellular infiltration into the vitreous cavity was detected at 24 hours and reached its maximum at 48 hours. CONCLUSIONS: This study demonstrates that it is possible to evaluate EIU by investigating retinal leukocyte behavior and that vasodilation of major retinal vessels and leukocyte-endothelial interactions precede inflammatory cell emigration into the vitreous. This method may be useful to quantify the severity of inflammation in EIU. (+info)
Interphotoreceptor retinoid binding protein is a potent tolerogen in Lewis rat: suppression of experimental autoimmune uveoretinitis is retinal antigen specific.
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AIMS: Administration of unfractionated retinal antigen(s) (retinal extract, RE) suppresses RE induced experimental autoimmune uveoretinitis (EAU) and offers a potential therapeutic alternative to non-specific immunosuppressive therapies for posterior uveitis and autoimmune diseases. S-Ag and interphotoreceptor retinoid binding protein (IRBP) are two major autoantigens within soluble RE. It was aimed to assess, firstly, as has previously been shown with S-Ag, if IRBP can induce intranasal tolerance and, secondly, the contribution of both these major autoantigens to tolerance induction by whole RE. METHODS: Animals were tolerised by intranasal administration with S-Ag or IRBP, either alone or in combination, or RE before immunisation with either IRBP or RE. Control animals were administered nasally either PBS or MBP. Daily clinical responses were recorded biomicroscopically and histological grades were obtained using a semiquantitative scoring system. Weekly serum antibody levels to retinal antigens were measured by ELISA and delayed hypersensitivity responses (DTH) were assessed by skin reactivity to intradermal inoculation with retinal or non-specific antigens. RESULTS: Microgram doses of IRBP successfully suppressed both clinically and histologically IRBP induced EAU. This suppression was accompanied by reduced antigen specific DTH reactivity but maintained T cell dependent (IgG2a) antibody responses. Furthermore, combined S-Ag and IRBP administration afforded equal suppression of RE induced EAU when compared with RE therapy alone. Suppression of RE induced EAU was not achieved with administration of a non-retinal specific autoantigen, MBP. Although individually, both S-Ag and IRBP suppressed RE induced EAU, whole RE was unable to protect against IRBP induced disease. CONCLUSIONS: Intranasal administration of IRBP suppressed IRBP induced EAU in the Lewis rat. S-Ag and IRBP are the major contributors to the tolerogenicity within RE, despite the known uveogenicity of other retinal antigens within RE and induction of tolerance was retinal antigen specific. Furthermore, suppression induced by single antigen administration is antigen specific although concomitant bystander suppression may also play a role. RE was unable to protect against IRBP induced disease despite tolerogenic levels of antigen within RE. Although this may be due in part to a dose effect of either tolerising or immunising antigen, further investigation into the possible antigen dominance of IRBP or mucosal processing of combinations of antigens is necessary so that the full efficacy of mucosal tolerance therapy can be assessed. (+info)