Reinhard G. Bretzel

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.

Once-daily basal insulin glargine versus thrice-daily prandial insulin lispro in people with type 2 diabetes on oral hypoglycaemic agents (APOLLO): an open randomised controlled trial.

BACKGROUND As type 2 diabetes mellitus progresses, oral hypoglycaemic agents often fail to maintain blood glucose control and insulin is needed. We investigated whether the addition of once-daily insulin glargine is non-inferior to three-times daily prandial insulin lispro in overall glycaemic control in adults with inadequately controlled type 2 diabetes mellitus taking oral hypoglycaemic agents. METHODS In the 44-week, parallel, open study that was undertaken in 69 study sites across Europe and Australia, 418 patients with type 2 diabetes mellitus that was inadequately controlled by oral hypoglycaemic agents were randomly assigned to either insulin glargine taken once daily at the same time every day or to insulin lispro administered three times per day. The primary objective was to compare the change in haemoglobin A(1c) from baseline to endpoint (week 44) between the two regimens. Randomisation was done with a central randomisation service. Analysis was per protocol. This study is registered with ClinicalTrials.gov, number NCT00311818. FINDINGS 205 patients were randomly assigned to insulin glargine and 210 to insulin lispro. Mean haemoglobin A(1c) decrease in the insulin glargine group was -1.7% (from 8.7% [SD 1.0] to 7.0% [0.7]) and -1.9% in the insulin lispro group (from 8.7% [1.0] to 6.8% [0.9]), which was within the predefined limit of 0.4% for non-inferiority (difference=0.157; 95% Cl -0.008 to 0.322). 106 (57%) patients reached haemoglobin A(1c) of 7% or less in the glargine group and 131 (69%) in the lispro group. In the glargine group, the fall in mean fasting blood glucose (-4.3 [SD 2.3] mmol/L vs -1.8 [2.3] mmol/L; p<0.0001) and nocturnal blood glucose (-3.3 [2.8] mmol/L vs -2.6 [2.9] mmol/L; p=0.0041) was better than it was in the insulin lispro group, whereas insulin lispro better controlled postprandial blood glucose throughout the day (p<0.0001). The incidence of hypoglycaemic events was less with insulin glargine than with lispro (5.2 [95% CI 1.9-8.9] vs 24.0 [21-28] events per patient per year; p<0.0001). Respective mean weight gains were 3.01 (SD 4.33) kg and 3.54 (4.48) kg. The improvement of treatment satisfaction was greater for insulin glargine than for insulin lispro (mean difference 3.13; 95% CI 2.04-4.22). INTERPRETATION A therapeutic regimen involving the addition of either basal or prandial insulin analogue is equally effective in lowering haemoglobin A(1c). We conclude that insulin glargine provides a simple and effective option that is more satisfactory to patients than is lispro for early initiation of insulin therapy, since it was associated with a lower risk of hypoglycaemia, fewer injections, less blood glucose self monitoring, and greater patient satisfaction than was insulin lispro. FUNDING Sanofi-Aventis.

Staphylococcus aureus extracellular adherence protein serves as anti-inflammatory factor by inhibiting the recruitment of host leukocytes

Staphylococcus aureus is a human pathogen that secretes proteins that contribute to bacterial colonization. Here we describe the extracellular adherence protein (Eap) as a novel anti-inflammatory factor that inhibits host leukocyte recruitment. Due to its direct interactions with the host adhesive proteins intercellular adhesion molecule 1 (ICAM-1), fibrinogen or vitronectin, Eap disrupted β2-integrin and urokinase receptor–mediated leukocyte adhesion in vitro. Whereas Eap-expressing S. aureus induced a 2–3-fold lower neutrophil recruitment in bacterial peritonitis in mice as compared with an Eap-negative strain, isolated Eap prevented β2-integrin-dependent neutrophil recruitment in a mouse model of acute thioglycollate-induced peritonitis. Thus, the specific interactions with ICAM-1 and extracellular matrix proteins render Eap a potent anti-inflammatory factor, which may serve as a new therapeutic substance to block leukocyte extravasation in patients with hyperinflammatory pathologies.

Differential accumulation of advanced glycation end products in the course of diabetic retinopathy

Aims/hypothesis. Glycated proteins, formed by reaction of glucose and protein, react further yielding numerous, mostly undefined advanced glycation end products (AGE). The recently characterized imidazolone-type AGE (AG-1) is non-oxidatively formed involving 3-deoxyglucosone whereas some AGEs, particularly Nɛ-(carboxymethyl)lysine (CML), are formed only in the presence of oxygen. Methods. To study the possible contribution of oxidative and non-oxidative AGE formation in the development of diabetic retinopathy antibodies directed against CML-type and imidazolone-type AGEs were characterized by dot blot analysis and used to localize these well-characterized epitops in the retinas from diabetic rats (early course) and from human Type I (insulin-dependent) diabetes mellitus with laser-treated proliferative diabetic retinopathy (late course). Results. In non-diabetic rats CML was moderately positive in neuroglial and vascular structures of non-diabetic rat retinas and increased strongly in diabetic retinas. Anti-imidiazolone antibody staining was strongly positive only in diabetic capillaries. Advanced human diabetic retinopathy showed strong CML-immunolabelling of the entire retina whereas control samples showed moderate staining of neuroglial structures only with the polyclonal CML-antibody. Anti-imidiazolone antibody staining was faint in the inner retina of control sections but were strong throughout the entire diabetic retina. Immunolabelling for the AGE-receptor was congruent with a marker of Müller cells. Conclusion/interpretation. Our data indicate that the oxidatively formed CML is present in non-diabetic retinas as a regular constituent but increases in diabetes both in neuroglial and vascular components. Imidazolone-type AGE are restricted to microvessels and spread during later stages over the entire retina, co-localizing with the expression of AGE-receptor. [Diabetologia (1999) 42: 728–736]

Comparative Analysis of Organ-Specific Autoantibodies and Celiac Disease—Associated Antibodies in Type 1 Diabetic Patients, Their First-Degree Relatives, and Healthy Control Subjects

OBJECTIVE In type 1 diabetes the coexistence with other endocrine diseases and organ-specific autoantibodies has been frequently reported leading to the concept of autoimmune polyendocrine syndrome (APS). In addition, an association of type 1 diabetes with celiac disease has been described. These disorders share a similar genetic background, and first-degree relatives of type 1 diabetic patients may also be affected significantly. Screening for specific antibodies allows early diagnosis of these disorders. RESEARCH DESIGN AND METHODS In the present cross-sectional study, we analyzed sera from 197 recent-onset type 1 diabetic patients at the time of diagnosis, 882 first-degree relatives, and sera of 150 healthy control subjects for prevalence and co-occurence of the following antibodies (method): insulin autoantibodies (radioimmunoassay); GAD and IA-2 antibodies (radioligand assay); islet cell antibody, anti-adrenal cortex antibodies, and anti-gastric parietal cell antibodies (indirect immunofluorescence); anti-thyroglobulin and anti-thyroid peroxidase antibodies; and gliadin IgG/A and tissue-transglutaminase IgA (enzyme-linked immunosorbent assay). RESULTS The overall frequency of gastric patietal cell antibodies and adrenal antibodies did not differ significantly among groups. In contrast, type 1 diabetes-associated antibodies and thyroid antibodies were significantly more frequent both in recent-onset type 1 diabetic patients and in the group of first-degree relatives (P < 0.05). The prevalence of gliadin IgG/IgA and transglutaminase IgA was significantly higher in the group of recent-onset type 1 diabetic patients (P < 0.05), but the difference between first-degree relatives and control subjects did not reach statistical significance. Focusing on the coexistence of antibodies, the group of recentonset type 1 diabetic patients presented with 27.4% of the subjects testing antibody-positive-specific for two or more of the envisaged disorders (i.e., type 1 diabetes, autoimmune thyroiditis, and celiac disease) compared with 3.1% in the group of first-degree relatives and 0 of 150 in the control population (P < 0.05). CONCLUSIONS We conclude that, in an active case-finding strategy, recent-onset type 1 diabetic patients should be routinely screened at least for concomitant autoimmune thyroid disease and additionally for celiac disease. Screening in their first-degree relatives should include at a minimum the search for thyroid autoimmunity in addition to screening for pre-type 1 diabetes.

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)

High prevalence of exocrine pancreatic insufficiency in diabetes mellitus: A multicenter study screening fecal elastase 1 concentrations in 1,021 diabetic patients

Background: There have been numerous reports on pancreatic exocrine dysfunction in diabetes mellitus using either direct or indirect function tests. The measurement of fecal elastase 1 concentrations (FEC) has been used as a screening tool for exocrine pancreatic disease in different patient groups indicating a high prevalence of exocrine dysfunction in diabetic populations. In this study we had the opportunity to study more than 1,000 diabetic patients to confirm recent observations in smaller populations. Methods: FEC were measured by ELISA in 323 patients with type 1 and 697 type 2 diabetes mellitus. Subjects with a history of alcohol abuse, gastrointestinal surgery, cancer or inflammatory diseases were not included. Diabetes history and clinical data were recorded using a standard case report form. Findings: 1,021 patients (334 female, 687 male; mean age 50 years; mean diabetes duration 11 years; mean age at onset of diabetes 39 years) were studied. FEC was normal (>200 µg/g) in 59.3% and severely reduced (<100 µg/g) in 22.9%. There were significant differences between type 1 and type 2 patients as well as between insulin-treated and non-insulin-treated patients. Furthermore, there were weak associations between FEC and diabetes duration, age at onset of diabetes and body mass index, respectively. Interpretation: We could confirm that both type 1 and type 2 diabetic patients show pathological exocrine function in high prevalence. Exocrine insufficiency seems to be correlated to early onset of endocrine failure, long-lasting diabetes mellitus and low body mass index levels.

Significant progress in porcine islet mass isolation utilizing Liberase HI for enzymatic low-temperature pancreas digestion

BACKGROUND Frequent success in human islet isolation is prevented by the large variability of scarce organ donors; this favors the future utilization of pigs as donors for clinical islet xenotransplantation. Porcine-specific difficulties of islet isolation are attributed to the intrinsic fragility of islets during pancreas digestion. METHODS To preserve islet integrity during efficient pancreas dissociation, porcine pancreata (n=48) were distended after cold storage with cold University of Wisconsin solution containing Liberase HI and digested at 24-28 degrees C using digestion-filtration. Pancreata distended with University of Wisconsin solution containing well-proven crude collagenase and digested at 32-34 degrees C served as controls (n=46). Monolayer Ficolldiatrizoate gradient purification was performed in a Cobe 2991. RESULTS Purified yield of islet equivalents per pancreas (mean+/-SEM) was almost doubled by Liberase HI compared with crude collagenase (526,480+/-46,560 vs. 270,270+/-19,420; P < 0.0001) and also significantly increased comparing islet equivalents per gram of pancreas (4,210+/-320 vs. 2,640+/-245; P=0.0004). Islet integrity was better preserved during Liberase HI digestion compared with crude collagenase digestion as indicated by isolation index (2.1+/-0.1 vs. 1.4+/-0.1; P<0.0001). Purity, viability, and in vitro function of islets did not differ between experimental groups. Preserved in vivo function of islets isolated by Liberase HI was demonstrated after subcapsular transplantation into 16 diabetic nude rats. CONCLUSIONS If the problems related to xenograft rejection and xenosis could be solved, low-temperature digestion of porcine pancreata using Liberase HI could serve as an essential prerequisite for successful 1:1 xenotransplantation of pig islets into type 1 diabetic human recipients.

Pancreatic exocrine function in patients with type 1 and type 2 diabetes mellitus.

Abstract Reduced exocrine pancreatic function has been observed in a high percentage of patients with type 1 diabetes in the past. There are only few data for type 2 diabetes available and they are contradictory. In this study we investigated exocrine pancreatic function in 105 controls and 114 with type 1 or type 2 diabetes mellitus by means of an indirect test (faecal elastase-1 concentration). This test has good sensitivity and specificity for moderate and severe pancreatic insufficiency as compared to the gold standard. Reduced faecal elastase-1 concentrations were found in 56.7% of type 1 patients, 35% of type 2 patients and 18.1% of the controls. Elastase-1 concentrations did not correlate with alcohol consumption, diabetes duration or diabetes therapy. The data found for type 1 patients correspond to those reported in earlier studies. The results for type 2 diabetics show that exocrine pancreatic function is also impaired in a high percentage in this group of patients. Pathogenic concepts to explain these findings as consequences of diabetes complications or insulin deficiency are still under debate. Observations from autopsies and the data of the controls in this study suggest that chronic pancreatitis might be a common problem. In consequence, diabetes secondary to exocrine disease could be much more frequent than believed so far.

Assessment of intracellular insulin content during all steps of human islet isolation procedure.

This study investigated the recovery of pancreatic insulin content during human islet isolation prior to and after digestion-filtration, continuous Hanks-Ficoll gradient purification (n = 20), and 3-4 day culture at 22 degrees C (n = 6). The native insulin content varied in a wide range from 28.4 U to 360.8 U/pancreas. After digestion the initially measured average insulin content of 115.8 +/- 20.8 U/pancreas (mean +/- SEM) increased to 264.6 +/- 22.8% (p < 0.001). This increase of insulin during pancreas digestion was attributed to the asymetrical distribution of insulin within the pancreas. Sampling of insulin within the pancreatic caput seemed not to be representative for the insulin content of the complete native organ, because the ratio of insulin per gram tissue within the pancreatic cauda compared to the caput (n = 5) was 2.4 +/- 0.4 (p < 0.05). After purification total insulin recovery was 55.3 +/- 4.8% (p < 0.001). Because recovery of islet equivalent number (IEQ) (83.7 +/- 4.4%) exceeded insulin recovery, insulin/IEQ ratio decreased from 656.8 +/- 70.6 microU/IEQ before purification to 436.4 +/- 58.1 microU/IEQ (p < 0.001) after purification. After 22 degrees C culture (n = 6) recovery of insulin and IEQ was 80.1 +/- 8.1% (p < 0.05) and 92.8 +/- 3.5% (p = NS), respectively. Insulin content per IEQ decreased to 85.8 +/- 6.5% (p < 0.05). This study clearly shows that most of islet insulin is lost during purification. This seems to be caused rather by an amplified insulin release than by the loss of islets itself. This release may facilitate the separation of endocrine and exocrine tissue by gradient centrifugation, but may also accelerate islet exhaustion detrimental for long-term insulin independence.