K. Federlin

Islet isolation assessment in man and large animals

SummaryRecent progress in islet isolation from the pancreas of large mammals including man, accentuated the need for the development of precise and reproducible techniques to assess islet yield. In this report both quantitative and qualitative criteria for islet isolation assessment were discussed, the main topics being the determination of number, volume, purity, morphologic integrity andin vitro andin vivo function tests of the final islet preparations. It has been recommended that dithizone should be used as a specific stain for immediate detection of islet tissue making it possible to estimate both the total number of islets (dividing them into classes of 50 µ diameter range increments) and the purity of the final preparation. Appropriate morphological assessment should include confirmation of islet identification, assessment of the morphological integrity and of the purity of the islet preparation. The use of fluorometric inclusion and exclusion dyes together have been suggested as a viability assay to simultaneously quantitate the proportion of cells that are intact or damaged. Perifusion of islets with glucose provides a dynamic profile of glucose-mediated insulin release and of the ability of the cells to down regulate insulin secretion after the glycemic challenge is interrupted. Although perifusion data provides a useful guide to islet viability the quantity and kinetics of insulin release do not necessarily predict islet performance after implantation. Therefore, the ultimate test of islet viability is their function after transplantation into a diabetic recipient. For this reason,in vivo models of transplantation of an aliquot of the final islet preparation into diabetic nude (athymic) rodents have been suggested. We hope that these general guidelines will be of assistance to standardize the assessment of islet isolations, making it possible to better interpret and compare procedures from different centers.

Impairment of Polymorphonuclear Leukocyte Function and Metabolic Control of Diabetes

Objective In this study, ingestion of Staphylococcus aureus and “bacteria killing” (BK) were measured to evaluate polymorphonuclear leukocyte (PMN) phagocytic functions and chemiluminescence response (CL) to phorbolmyristic acetate (PMA) as respiratory burst activity with regard to metabolic control parameters in diabetic patients. Research Design and Methods PMN phagocytic functions were assessed in 40 diabetic patients, all receiving insulin and in poor metabolic control, with 3H-thymidine-labeled Staphylococcus aureus in a modified radiometric assay. Bacteria killing was determined by pure-plate counting of surviving bacteria (colony-forming units [cm]) and luminol-enhanced CL in response to PMA as a measure of respiratory burst. PMN function data were correlated to HbA1 as parameter of recent metabolic control. Results PMN of diabetic patients showed a significant reduction in Staphylococcus aureus (50.7 ± 4.1%) and BK (29.4 ± 4.2%) compared with healthy nondiabetic control subjects (76.6 ± 4.6% and 16.3 ± 3.1%, respectively, P < 0.001), and PMN CL response was markedly reduced in diabetic patients also. Linear regression analysis showed a highly significant negative correlation of HbAi versus Staphylococcus aureus (r = -0.67, P = 0.001) and a positive correlation for BK (r = 0.73, P < 0.001). This was also true for CL, although this did not reach statistical significance (P = 0.06). Conclusions The data obtained demonstrate impaired PMN phagocytic functions and CL response in diabetic patients. These findings suggest inhibitory effects of elevated glucose concentrations on PMNs, a possible role of protein glycosylation for impairing PMN function, thus contributing in part to altered host defense.

Mexiletine in the Treatment of Diabetic Neuropathy

OBJECTIVE To prove the efficacy of mexiletine in painful diabetic neuropathy. RESEARCH DESIGN AND METHODS Treatment was provided in three dosages. For pain measurements, a VAS and McGills verbal rating scale were chosen. Ninety-five patients were included in the study. RESULTS A global assessment of the VAS among patients showed no differences between mexiletine treatment and placebo. The total evaluation (PRIT) of the McGill scale fell just below the level of significance. More specific exploratory evaluations of subclasses of the McGill scale, representing different degrees of pain, gave remarkable differences between mexiletine and placebo in sensory and miscellaneous items. In special subgroups, which were formed according to types and courses of complaints compiled at the beginning of this evaluation, the substantial advantages of the mexiletine treatment were shown with both the VAS and the McGill scale. CONCLUSIONS Evidence strongly indicates that, in particular, those patients with stabbing or burning pain, heat sensations, or formication will benefit most by mexiletine therapy. Concerning the dosage, a medium regimen of 450 mg/day seems to be appropriate. With an increase in the antiarryhthmic dosage level, the efficacy does not rise proportionally. Mexiletine proved to be a safe therapy with negligible side effects at the medium dose range, even < placebo; and remarkably, no cardiovascular side effects were noted. Further studies should avoid global assessments and pay more attention to the variety of complaints and quality of life.

Production of purified alginates suitable for use in immunoisolated transplantation.

Alginate is used as a matrix for immunoisolation of cells and tissues in vivo. We have demonstrated previously that commercial alginates contain various fractions of mitogenic impurities and that they can be removed by free flow electrophoresis. The use of purified material is a necessity in order to reveal the parameters that control biocompatibility of the implanted material (such as stability, size, surface charge and curvature, etc.). In this study, we present a protocol for the chemical purification of alginates on a large-scale. Beads made from alginates purified by this multi-step chemical extraction procedure did not induce a significant foreign body reaction when implanted for 3 weeks either intraperitoneally or beneath the kidney capsule of Lewis or non-diabetic BB/Gi rats.

Aminoguanidine inhibits the development of accelerated diabetic retinopathy in the spontaneous hypertensive rat

SummaryArterial hypertension has been identified as a major secondary risk factor for diabetic retinopathy. However, the mechanisms by which hypertension worsens retinopathy are unknown. Inhibition of advanced glycation product formation prevents the development of experimental diabetic retinopathy in normotensive diabetic rats. In this study the effect of hypertension on the rate of diabetic retinopathy development and the formation of arteriolar thrombosis was evaluated. We also evaluated the effect of aminoguanidine, an inhibitor of advanced glycation end product formation on retinal pathology of diabetic hypertensive rats. After 26 weeks of diabetes, hypertension accelerated the development of retinopathy despite a lower mean blood glucose level than in the non-hypertensive group (diabetic spontaneous hypertensive rats (SHR) 16.00±6.83 mmol/l; diabetic normotensive Wistar Kyoto rats (WKY) 34.9±3.64 mmol/l; p<0.0001). Diabetic SHR had nearly twice as many acellular capillaries as diabetic WKY (SHR diabetic: 91.9±7.5 acellular capillaries per mm2 of retinal area vs WKY diabetic: 53.7±8.5 acellular capillaries per mm2 of retinal area), and a 3.8-fold increase in the number of arteriolar microthromboses (SHR diabetic 23504±5523 μm2 vs SHR non-diabetic 6228±2707 μm2). Aminoguanidine treatment of SHR diabetic rats reduced the number of acellular capillaries by 50%, and completely prevented both arteriolar deposition of PAS-positive material and abnormal microthrombus formation. These data suggest that hypertension-induced deposition of glycated proteins in the retinal vasculature plays a central role in the acceleration of diabetic retinopathy by hypertension.

Nephroprotective Effects of Nitrendipine in Hypertensive Tune I and Type II Diabetic Patients

Hypertension is significantly involved in the progression of diabetic nephropathy and in the development of end stage renal disease in both type I and type II diabetes mellitus. We have investigated whether long-term monotherapy with a calcium antagonist, nitrendipine, prevents the development of overt diabetic nephropathy in type I and type II diabetic patients with mild to moderate hypertension and persistent microalbuminuria (ie, incipient nephropathy). After a 4-week run-in and washout period, respectively, 25 patients met the inclusion criteria. Twenty-two patients (six with type I and 16 with type II diabetes) completed the 12-month study. Twelve months of treatment with nitrendipine resulted in a significant reduction in systolic blood pressure in patients with type I (157.5 +/- 8.1 mm Hg v 135.8 +/- 4.2 mm Hg, P < 0.05) and type II (163.1 +/- 4.3 mm Hg v 135.9 +/- 3.6 mm Hg, P < 0.001) diabetes. A significant reduction also was seen in diastolic blood pressure (91.7 +/- 1.7 mm Hg v 79.2 +/- 3.5 mm Hg in type I diabetic patients, P < 0.01; 94.7 +/- 1.4 mm Hg v 78.1 +/- 1.5 mm Hg in type II diabetic patients, P < 0.001). A significant reduction in albuminuria was associated with the blood pressure reduction in both type I (57.8 +/- 11.9 mg/24 hr v 24.9 +/- 5.9 mg/24 hr, -57%) and type II (134.6 +/- 20.7 mg/24 hr v 70.3 +/- 16.8 mg/24 hr, -48%) diabetic patients. The mean glomerular filtration rate increased by 21% (112 +/- 12 mL/min v 135 +/- 14 mL/min) and by 23% (106 +/- 12 mL/min v 130 +/- 14 mL/min) in type I and type II diabetic patients, respectively. No significant changes were found in renal plasma flow rates or in serum concentrations of beta 2-microglobulin. With the exception of a significant (P < 0.05) reduction in hemoglobin A1 concentration in type II diabetic patients after 3 months of treatment with nitrendipine, fasting blood glucose, hemoglobin A1, residual beta-cell function (C-peptide levels), total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, and body mass index remained essentially unchanged during follow-up. These findings suggest that 12 months of monotherapy with the dihydropyridine-type calcium antagonist nitrendipine reduced albuminuria and increased the lowered glomerular filtration rate without adverse effects on glucose and lipid control.(ABSTRACT TRUNCATED AT 400 WORDS)

Clinical islet transplantation--registry report, accomplishments in the past and future research needs.

This review provides the results of a recent analysis of the Islet Transplant Registry on clinical adult islet transplants performed worldwide through June 30, 1992. Between December 12, 1893 and June 30, 1992, 167 adult islet transplants were performed at 25 institutions worldwide, including 104 at 9 institutions in North America, 62 at 15 institutions in Europe, and 1 elsewhere. The total number of diabetic patients reported to be insulin independent after adult islet allotransplantation through June 30,1992, was 19. In an analysis by era, the percentage of patients that showed positive basal C-peptide levels (i.e. ≥ 1 ng/mL at ≥ 1 mo) posttransplant, and that became insulin independent (>1 wk) in the 1985-1989 era (n = 35 cases) were 20% and 6%, and in the 1990-1992 era (n = 69 cases) were 64% and 20%, respectively, and thus have improved significantly (p < 0.001 and p < 0.05). For the 1990-1992 period, the percentage of patients who showed positive basal C-peptide levels post-transplant, and who became insulin independent in the single donor pancreas group (n = 31 cases) were 52% and 13%, and in the multiple donor pancreata group (n = 36 cases) were 75% and 28%, respectively. Islet graft function rates were nearly identical for grafts prepared from pancreata stored ≤6 h (n = 27) and >6 ≤ 12 h (n = 29), so that 67% and 72% showed positive basal C-peptide levels, and 30% and 21% of the recipients became insulin independent, respectively. No single patient showed islet graft function sufficient to allow withdrawal from insulin, if the pancreata have been stored for more than 12 h. In regard to recipient category for the six groups, namely IAK (islet after kidney), SIK (simultaneous islet kidney transplantation), SIL (simultaneous islet liver transplantation), SIL(C) (simultaneous islet liver transplantation after cluster operation), SIKL (simultaneous islet kidney liver transplantation), and SIH-L (simultaneous islet heart-lung transplantation), the number of patients who showed positive basal C-peptide levels post-transplant was 11 (58%), 17 (57%), 5 (83%), 8 (80%), 1 (50%), and 0 (0%), and the number of insulin independent patients was 4 (21%), 4 (13%), 0 (0%), 6 (60%), 0 (0%), and 0 (0%), respectively. Comparing the two largest recipient categories, namely IAK and SIK, no difference in the outcome of these transplants was apparent. The only sites of transplantation in the period between 1990-1992 were the liver, epiploic flap, and spleen, with the total number of recipients being 60 (90%), 4 (6%), and 3 (4%), respectively. For these three groups, the number of patients who showed positive basal C-peptide levels was 38 (63%), 2 (50%), and 1 (33%), and the number of insulin independent patients was 13 (22%), 0 (0%) and 0 (0%), respectively. In the overwhelming majority of cases, recipient selection was not based on prospective HLA donor/recipient matching. In different categories of HLA mismatching (i.e., AB-, DR-, BDR-, and ABDR-mismatch) no obvious tendency or difference in outcome could be demonstrated. In the 1990-1992 period, 16 patients (24%) received OKT3, 26 patients (39%) received ALS, ALG, or ATG, and 25 patients (37%) received neither monoclonal nor polyclonal T-cell antibodies for induction immunosuppression. For the three groups mentioned, the number of patients who showed positive basal C-peptide levels was 12 (86%), 16 (62%), and 15 (60%), and the number of insulin independent patients was 2 (14%), 6 (23%), and 6 (24%), respectively. A synopsis of all pretransplant C-peptide-negative Type I diabetic patients who succeeded in insulin independence revealed certain common characteristics, such as transplantations of ≥8000 islet equivalents per kilogram body weight, a purity of transplanted islets ≥ 50% (in all but one case), the liver as implantation site, and OKT3 or ALG/ ALS/ATG for induction immunosuppression (“state of the art” cases). Because it has been unequivocally proven that islet transplantation can be performed successfully in association with other organ transplants, more attention should be drawn to the nonuremic, nonkidney Type I diabetic patients, who have not been reported in a single case since 1990. This is the real target group, that could benefit most from islet replacement. However, islet transplantation in this recipient category will only have an undisputable indication, if low-risk, but effective methods other than life-long immunosuppression to protect the islet graft from rejection can be developed.

Secondary intervention with aminoguanidine retards the progression of diabetic retinopathy in the rat model

SummaryPrimary prevention with aminoguanidine — an inhibitor of advanced glycation end product (AGE) formation — has been successfully employed to prevent diabetic retinopathy in the rat. However, it is unknown whether inhibition of AGE formation is still effective in a secondary intervention strategy. The present study addresses this question by comparing secondary intervention with aminoguanidine with syngeneic islet transplantation in the rat model. After 6 months of diabetes, one group was treated with aminoguanidine (50 mg/100 ml drinking water; D-AG) while another group received syngeneic transplantation of collagenase-ficoll isolated islets by intraportal injection (Tx). After an additional 4 months, both groups were compared to a normal (NC 10) and diabetic (DC 10) control group. Retinal autofluorescence was increased 2.5-fold after 6 months and increased 3.7-fold after 10 months of diabetes (p<0.001). Aminoguanidine and islet Tx retarded the further accumulation of autofluorescence equally (p<0.001 vs DC 10), although the values were higher than those observed in DC at 6 months (p<0.001). Diabetes was associated with a 2.7-fold increase in acellular capillaries after 6 months and a 4.1-fold increase after 10 months. Treatment with aminoguanidine or islet Tx reduced but did not completely attenuate the progression of vascular occlusion (p<0.001 vs DC 10; D-AG vs DC 6, p<0.05; Tx vs DC 6, p<0.01). Both treatments reduced endothelial proliferation (22.4% after 10 months; p<0.001) and completely arrested pericyte dropout (40% after 10 months; p<0.001).These data demonstrate that aminoguanidine is as effective as islet transplantation in retarding the progression of diabetic retinopathy in a secondary prevention setting.

Bone metabolism and bone mineral density of systemic lupus erythematosus at the time of diagnosis

Abstract Recent studies have shown that systemic lupus erythematosus (SLE) is associated with a loss of trabecular bone. However, these changes have not been not described in patients with SLE at the time of diagnosis. To investigate the markers of bone metabolism 20 female patients with a recently manifested clinical picture of SLE were selected. All patients included in this study met the ARA criteria (for classification) of SLE. For comparison, 35 female patients with SLE, which had previously manifested itself and which had been treated with glucocorticoids, were included in a second group. A control group (III) consisting of 20 healthy individuals of the same age was formed to compare the results obtained. Test parameters comprised both serum levels of osteocalcin (OC) as the marker for bone formation and crosslinks excretion (CE) in urine as a specific marker for bone resorption. The bone density (BMD) was examined by dual energy X-ray absorption (DEXA) of the vertebral column (L2–L4), femoral neck, Wards triangle and trochanter. The patients under study received either no medication or nonsteroidal antirheumatic drugs. The BMD of the vertebral column was significantly lower than expected in SLE-afflicted subjects of group II when compared with the age-matched normal female controls. The reduction of BMD in female patients with SLE was related to the significantly increased excretion of urinary pyridinoline, to hypoparathyroidism, and to the decrease in serum OC. Bone loss in women with fresh manifestation of SLE (I) increases to a degree similar to that of patients in group II. Lowered BMD predicts an increased risk for bone fractures. Therefore, female premenopausal SLE patients should be monitored for osteoporosis.

International islet transplant registry report

Long-term studies strongly suggest that tight control of blood glucose levels achieved by conventional intensive insulin treatment, self-blood glucose monitoring and patient’s education can significantly prevent the development and retard the progression of chronic complications of type 1 diabetes mellitus [1, 2]. The expense for this benefit was a threefold increase of the number of severe hypoglycemic episodes, a significant increase of the body weight, and dietary and other life-style restrictions affecting the quality of life.