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R G Bretzel

Publications and source records attributed to R G Bretzel.

At least 55 records · Page 3Linked to original sources
PubMed2001

Islet transplantation as treatment of type 1 diabetes: from experimental beginnings to clinical application.

Experimental islet transplantation started more than 30 years ago when it was discovered that isolation of the islets of Langerhans from the exocrine tissue of the pancreas was possible with collagenase. In numerous studies over the following years in rodents it was shown that transplantation of a sufficient number of islets into the liver via the portal vein shortly after diabetes induction of the recipient resulted in normoglycemia, aglycosuria, normal body weight and the typical diabetic late complications were prevented. However, those results were limited for the syngeneic system, when allogeneic islets were transplanted rejection occurred within a few days. Immunosuppressive regimen showed only limited success in rodents while immunoalteration procedures (culture at low temperatures, UV light irradiation, cryopreservation etc.) were capable to prolong the survival of islets up to 200 days. In contrast to the rodent model in larger animals as pigs, dogs and monkeys immunosuppressive drugs (single and in combination) resulted in marked prolongation of allograft survival while immunoalteration of islets with those animals was less successful. Because a broader use of islet transplantation in man will lead to shortage of donor organs xenotransplantation may be possibly a solution which is briefly mentioned.--Finally, new strategies regarding the production of human insulin producing cells for transplantation purposes are discussed.--In summary, experimental islet transplantation has paved the way for using this treatment in human patients.

Animals↗
PubMed2001

Islet transplantation: present clinical situation and future aspects.

Beta-cell replacement either by pancreatic organ or islet cell transplantation is the only treatment to achieve an insulin-independent, normoglycemic state and to avoid hypoglycemic episodes in patients with type 1 diabetes mellitus. This article will review the state-of-the-art in clinical islet cell transplantation at the dawn of the new millennium and will provide an outlook on the basis of extended personal experience.

Graft Rejection↗
PubMed2001

Metabolic effects of restoring partial beta-cell function after islet allotransplantation in type 1 diabetic patients.

Successful intraportal islet transplantation normalizes glucose metabolism in diabetic humans. To date, full function is not routinely achieved after islet transplantation in humans, with most grafts being characterized by only partial function. Moreover, the duration of full function is variable and cannot be sufficiently predicted with available methods. In contrast, most grafts retain partial function for a long time. We hypothesized that partial function can restore normal protein and lipid metabolism in diabetic individuals. We studied 45 diabetic patients after islet transplantation. Labeled glucose and leucine were infused to assess whole-body glucose and protein turnover in 1) 6 type 1 diabetic patients with full function after intraportal islet transplantation (FF group; C-peptide > 0.6 nmol/l; daily insulin dosage 0.03 +/- 0.02 U x kg(-1) body wt x day(-1); fasting plasma glucose < 7.7 mmol/l; HbA1c < or = 6.5%), 2) 17 patients with partial function (PF group; C-peptide > 0.16 nmol/l; insulin dosage < 0.4 U x kg(-1) body wt x day(-1)), 3) 9 patients with no function (NF group; C-peptide < 0.16 nmol/l; insulin dosage > 0.4 U x kg(-1) body wt x day(-1)), and 4) 6 patients with chronic uveitis as control subjects (CU group). Hepatic albumin synthesis was assessed in an additional five PF and five healthy volunteers by means of a primed-continuous infusion of [3,3,3-2H3]leucine. The insulin requirement was 97% lower than pretransplant levels for the FF group and 57% lower than pretransplant levels for the PF group. In the basal state, the PF group had a plasma glucose concentration slightly higher than that of the FF (P = 0.249) and CU groups (P = 0.08), but was improved with respect to the NF group (P < 0.01). Plasma leucine (101.1 +/- 5.9 micromol/l) and branched-chain amino acids (337.6 +/- 16.6 micromol/l) were similar in the PF, FF, and CU groups, and significantly lower than in the NF group (P < 0.01). During insulin infusion, the metabolic clearance rate of glucose was defective in the NF group versus in the other groups (P < 0.01). Both the basal and insulin-stimulated proteolytic and proteosynthetic rates were comparable in the PF, FF, and CU groups, but significantly higher in the NF group (P = 0.05). In addition, the PF group had a normal hepatic albumin synthesis. Plasma free fatty acid concentrations in the PF and FF groups were similar to those of the CU group, but the NF group showed a reduced insulin-dependent suppression during the clamp. We concluded that the restoration of approximately 60% of endogenous insulin secretion is capable of normalizing the alterations of protein and lipid metabolism in type 1 diabetic kidney recipients, notwithstanding chronic immunosuppressive therapy. The results of the present study indicate that "success" of islet transplantation may be best defined by a number of metabolic criteria, not just glucose concentration/metabolism alone.

Adult↗
PubMed2001

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.

Adolescent↗
PubMed2000

Effect of long-term dietary protein intake on glucose metabolism in humans.

AIMS/HYPOTHESIS: A meal rich in protein stimulates insulin secretion. Long-term effects of dietary protein on insulin release and glucose metabolism are, however, still not known. Our study focussed on the effect of different protein intake on pancreatic insulin secretion capacity, glycogen turnover and gluconeogenesis. METHODS: Subjects with constant (6 months) dietary protein of 1.87 +/- 0.26 g kg(-1) day(-1) (1.25-2.41) named high protein group and with 0.74 +/- 0.08 (0.57-0.80), normal protein group, were identified by a food questionnaire and were matched (n = 9) according to sex, age and calorie intake. They underwent an intravenous glucose tolerance test and a euglycaemic hyperinsulinaemic clamp with infusion of [6,6-2H2]-glucose combined with indirect calorimetry. To estimate net gluconeogenesis the usual diet was enriched by deuterated water or U-[13C6]-glucose and breath and plasma were sampled. RESULTS: Glucose-stimulated insulin secretion was increased in the high protein group (516 +/- 45 pmol/l vs 305 +/- 32, p = 0.012) due to reduced glucose threshold of the endocrine beta cells (4.2 +/- 0.5 mmol/l vs 4.9 +/- 0.3, p = 0.031). Endogeneous glucose output was increased by 12% (p = 0.009) at 40 pmol/l plasma insulin in the high protein group, but not at higher insulin concentration whereas overall glucose disposal was reduced. Fasting plasma glucagon was 34% increased in the high protein group (p = 0.038). Fractional gluconeogenesis was increased by 40% in subjects receiving a high protein diet as determined by both methods. CONCLUSION/INTERPRETATION: High protein diet is accompanied by increased stimulation of glucagon and insulin within the endocrine pancreas, high glycogen turnover and stimulation of gluconeogenesis.

Adult↗
PubMed2000

Current status and perspectives in clinical islet transplantation.

Beta-cell replacement, by either pancreas or islet transplantation, is the only treatment to achieve an insulin-independent, constantly normoglycemic state avoiding hypoglycemic episodes in patients with type-1 diabetes mellitus. This article reviews the current state of the worldwide experience based on data provided by the International Islet Transplant Registry; it also illustrates the perspectives of clinical islet transplantation.

Diabetes Mellitus, Type 1↗
PubMed2000

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

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 patients 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. Pathogenetic 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.

Adult↗
PubMed2000

Changes in calciotropic hormones and biochemical markers of bone metabolism in patients with human immunodeficiency virus infection.

Data on the bone metabolism of human immunodeficiency virus (HIV)-infected patients are still extremely rare. To investigate the influence of HIV infection on the calciotropic hormones and markers of bone metabolism, we therefore performed a cross-sectional study on 100 patients (65 males and 35 females) with proven HIV infection. The following criteria were used for exclusion from the study: age less than 20/more than 50 years, confinement to bed, wasting symptoms, treatment with agents containing ketoconazole, renal or hepatic insufficiency, clinical or echographic signs of liver cirrhosis, endocrine diseases, or treatment with medications known to influence bone metabolism. Bone mineral content (BMC) was determined by single-photon absorptiometry on the left forearm. Reduced BMC was found among the male and female HIV-infected patients. Additional long-term use of heroin resulted in a severe loss of mineralization in the respective females. The markers of bone metabolism were determined in urine and serum samples. Significantly lower osteocalcin concentrations were found, indicating a reduced bone formation rate whose severity showed a significant correlation with the progressive loss of CD4 helper cells and was independent of low vitamin D3 levels (1,25-dihydroxycholecalciferol) and alterations of protein metabolism. Increased urinary excretion of cross-links as an expression of enhanced bone resorption was likewise significantly correlated with the loss of CD4 helper cells and independent of the vitamin D concentration and protein metabolism. It is therefore concluded that the changes in bone metabolism are mainly due to mechanisms of the impaired immune defense of HIV-infected patients.

Adult↗
PubMed2000

Islet autoantibodies as potential markers for disease recurrence in clinical islet transplantation.

At present, indications for clinical islet transplantation exist almost exclusively in type-1 diabetic patients with end-stage renal disease receiving the islets either simultaneously with or after an already established kidney graft. This implies, that islet transplantation is performed in type-1 diabetic patients with long disease duration. The fate of the islet allograft is determined by a combination of immunological effector mechanisms. Beside early non-specific inflammation and alloreactivity, chronic autoimmunity may contribute to islet graft failure. The immunologic characterization of the prediabetic state has considerably progressed, whereas, the nature of autoimmunity years and decades after the onset of diabetes is largely unknown. Islet autoantibodies as surrogate markers for islet autoimmunity are well established in prediabetic periods of type-1 diabetes. In contrast, only few data exists in the setting of long-term type-1 diabetic patients undergoing islet transplantation. This article reviews the original data from the Giessen islet transplantation project and the pertinent literature with respect to islet autoimmunity and disease recurrence. It is demonstrated, that autoimmunity may persist in an individual with type-1 diabetes for decades after diabetes onset and that autoimmune responses to transplanted islets are resistant to the immunosuppressive drugs currently used. It is suggested from pilot trials, that type-1 diabetic patients with persistent autoantibodies and individuals, in whom autoantibodies become detectable after the transplantation are at higher risk for early islet graft failure potentially due to recurrent autoreactivity directed to the islet graft.

Autoantibodies↗
PubMed1999

Thyroid disorders in female patients with ankylosing spondylitis.

The association between rheumatological and thyroid disorders has long been known, the most common being the association of rheumatoid arthritis and autoimmune thyroiditis. Little is known as to possible thyroid involvement in ankylosing spondylitis (AS). In 22 female patients with AS and 22 healthy age-matched control subjects parameters of thyroid gland function, rheumatic activity, as well as a subtle drug anamnesis of the rheumatic medication, and an ultrasonographic examination of the thyroid gland were determined. Thyroid function was tested by intravenous injection of 400 microg thyrotropin-releasing hormone (TRH). In parallel basal levels of reverse-T3 (rT3), calcium and anti-thyroid antibodies were estimated. In the AS-group an enlarged thyroid volume was seen in 10 cases, basal FT4, FT3 and TT3 were significantly lower, TSH and TT4 were found to be in the normal range and rT3 was significantly increased. The prevalence of anti-thyroid antibodies was significantly higher in the AS-group. The AS-patients responded as well as the controls with thyroid hormone secretion to TRH, within an observation period of 2 hours. No differences were observed in TSH response. Free serum calcium showed in both groups no significant difference. To summarize our results, female patients with AS showed a

Adult↗
PubMed1999

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.

Adenosine↗
PubMed1999

Long-term survival, morphology and in vitro function of isolated pig islets under different culture conditions.

BACKGROUND: Islet culture aims to optimize islet survival and to reduce islet immunogenicity. To achieve these objectives, culture periods at 37 degrees C and 22-24 degrees C are mainly used. METHODS: This study compares the influence of donor age (juvenile vs. adult), temperature (22 degrees C vs. 37 degrees C), and serum supplementation (10% newborn calf serum [NCS] with 10% pig serum) on morphological integrity and in vitro function of porcine islets during long-term culture (LTC). RESULTS: After 21 days at 22 degrees C, the survival rate of cultured islets isolated from juvenile donors was lower than of adult islets (23+/-0.9% vs. 88+/-2.8%, P<0.001). Compared with 37 degrees C, LTC at 22 degrees C increased survival of adult islets and DNA recovery (92+/-2.5% vs. 45+/-4.8%, P<0.001; 72+/-4.1% vs. 30+/-5.1%, P<0.001) and reduced viability (62+/-8% vs. 89+/-5%, P<0.05). LTC at 22 degrees C was associated with a reduction of insulin content (85+/-9 vs. 152+/-10 microU/islet equivalents [IEQ], P<0.01), 24 hr-insulin secretion (82+/-7 vs. 552+/-91 microU/ day/IEQ, P<0.001), and integrated dynamic insulin response to glucose (1093+/-124 vs. 3074+/-708 microU/60 min/100 IEQ, P<0.05), compared with 37 degrees C LTC. Histologic analysis revealed disintegration of islet periphery after 22 degrees C, whereas smoothly shaped islets were present after 37 degrees C LTC. Integrity after 14 days at 37 degrees C was significantly better preserved when medium CMRL 1066 was supplemented with 10% porcine serum, compared with 10% NCS (40+/-2.3% vs. 21+/-6.7%, P<0.05), contrasting with 22 degrees C (52+/-4.0% vs. 59+/-3.7%, not significant). CONCLUSIONS: This study demonstrates that survival of cultured porcine islets is increased at 22 degrees C, whereas in vitro function and viability are better preserved at 37 degrees C. Survival at 37 degrees C can be improved by adding homologous serum to the medium.

Animals↗
PubMed1999

Molecular cloning of a full-length cDNA for human type 3 adenylyl cyclase and its expression in human islets.

The GK (Goto-Kakizaki) rat is a lean model of type 2 diabetes in which the diabetic state was spontaneously induced. We recently demonstrated the presence in GK rats of two functional point mutations in the promoter region of the type 3 adenylyl cyclase (AC3) gene that resulted in overexpression of AC3 mRNA associated with increased cAMP generation. The AC3 gene promoter mutations are the first molecular changes to be described in any specific gene in the GK rat. Here we report cloning of a full-length cDNA encoding human AC3 from a human fetal brain cDNA library using a PCR-based screening method. This 4142-bp cDNA predicts an open reading frame encoding 1144 amino acids containing putative 12 transmembrane-spanning domains which are typically found in other mammalian AC isoforms. Comparison of the translated amino acid sequence of the AC3 gene between human and rat shows 95% homology. Using RT-PCR, clear AC3 expression was detected in isolated human islets as well as a cDNA panel containing templates from eight different tissues (brain, heart, kidney, liver, lung, pancreas, placenta, and skeletal muscle). This wide distribution of AC3 expression may involve a number of physiological and pathophysiological metabolic processes.

Adenylyl Cyclases↗
PubMed1999

Glutamic acid decarboxylase antibodies are more frequent than islet cell antibodies in islet transplanted IDDM patients and persist or occur despite immunosuppression.

Pancreatic islet grafts transplanted into patients with autoimmune diabetes are potentially threatened by two immune responses, allograft rejection and the recurrence of autoimmune insulitis. In the present study we investigated the humoral autoimmune response directed to islet autoantigens by studying islet cell antibodies and glutamic acid decarboxylase (GAD 65) antibodies in twenty-one insulin-dependent diabetes-mellitus (IDDM) patients undergoing intraportal islet allotransplantation. Islet transplantation was performed according to the following recipient categories: Islet after kidney transplantation (n=10), simultaneous islet and kidney transplantation (n=6) and islet transplant alone (n=5). GAD 65 antibodies were detected in a radioligand GAD 65 antibody assay using recombinant, in vitro translated, human 35S-methionin labelled GAD 65 as tracer. Islet cell antibodies were determined by indirect immunofluorescence technique on human pancreas. In six out of twenty-one patients we observed GAD 65 antibodies before islet transplantation and the GAD 65 antibodies persisted despite immunosuppression. In contrast only two subjects were concordantly islet cell antibody positive and the titre decreased post transplantation. In addition we observed occurrence of GAD 65 antibodies in five subjects that were shown to be antibody negative before islet transplantation with three of them subsequently becoming positive for islet cell antibodies. The remaining ten patients were GAD 65 antibody and islet cell antibody negative before islet transplantation and remained negative thereafter. Interestingly none of the patients was exclusively positive for islet cell antibodies without being positive for GAD 65 antibodies. In summary we have demonstrated in twenty-one islet grafted individuals that humoral autoimmunity to islet antigens can persist or occur despite immunosuppression. Islet cell antibodies appear to be less frequent (5 out of 21, 23%) compared to GAD 65 antibodies (11 out of 21, 52%) suggesting that they are more affected by immunosuppressive therapy. We conclude that GAD 65 antibodies are a useful tool to further evaluate a possible link between persistent autoimmunity and early or late graft failure after islet transplantation.

Autoantibodies↗
PubMed1999

Evidence for a significant correlation of donor pancreas morphology and the yield of isolated purified human islets.

In clinical islet transplantation to patients with type 1 diabetes mellitus, the number of isolated and purified islet has been identified as a key determinant for functional success of the islet graft. With improved isolation methods based on the original procedure published by Ricordi et al. yield and function of isolated islets were considerably enhanced. However, there is still a large variance in the number, purity, viability and secretory capacity of islets isolated from brain-dead human donor pancreata, significantly hampering utilization of human islet preparations derived from a single donor for one diabetic recipient. The reasons for the limited success in islet isolation and purification have not been clarified in detail yet. Recent studies have indicated, that donor preconditions, and a number of technical factors during organ procurement and the islet isolation process itself are critical to successful islet isolation. This study aimed at identifying distinct morphological and histopathological characteristics of the donor pancreas as determinants for the outcome of human islet isolation and purification.

Biopsy↗
PubMed1999

Glucose sensitivity of porcine and human islets in vitro.

Preliminary experiments about the suitability of different commonly used culture media in our laboratory indicated, that prolonged exposure to high glucose concentrations during low temperature culture (LTC) impairs the viability of long term cultured human islets. As a consequence of the heterogeneity of tested media the present study was aimed to evaluate the influence of different glucose concentrations on survival, viability and in-vitro function of cultured human islets in order to optimize islet survival until transplantation and to compare species dependent differences in glucose sensitivity. Quantified aliquots of freshly isolated (digestion-filtration, ficoll gradient purification) islets from consecutively processed human (n=6) and porcine (n=11) pancreata were subjected to different glucose concentrations (human islets: 500, 750, 1000 and 2000 mg/l; porcine islets: 1000 and 2000 mg/l) in CMRL (22 degrees C) for 8-10 days. After LTC survival, viability and glucose-stimulated insulin release of incubated tissue was assessed. A reduction of glucose concentration promotes survival and viability of human islets but impairs in vitro function at the same time, presumably due to a reduced glucose oxidation as expressed by the significantly reduced stimulation index. In contrast to these findings in the human, elevated glucose concentration in porcine islet culture increases survival but reduces the glucose-stimulated insulin release and the viability of cultured islets. The contradiction of the results in regard to islet survival related to islet viability are still unclear in the pig and needs further evaluation.

Animals↗
PubMed1999

Large variability of the intracellular ATP content of human islets isolated from different donors.

Observations in experimental heart, liver, kidney and pancreas transplantation indicated that graft function and survival correlates significantly with ATP content of transplanted tissue. The ATP content of cells can be reduced by several factors i.e. the nutritional donor status, storage technique, warm ischemia and cold ischemia time. This study investigates the intracellular ATP content of isolated human islets for the first time. Quantified samples of freshly isolated (digestion-filtration, continuous ficoll gradient purification) and cultured (22 degrees C, CMRL+10% FCS) islet equivalents (IEQ) of consecutively processed human pancreata from multiorgan donors (UW vascular flush) were shock frozen in liquid nitrogen and stored at -196 degrees C until rapid thawing, sonification and subsequent luminometric determination of ATP (Luciferin-Luciferase-reaction) and assessment of islet protein (IP). The ATP content was analysed for freshly isolated and subsequently 5+/-1 days cultured islets (n=10). The ATP content of freshly isolated human islets was 130.4+/-53.4 pg/microg IP (mean+/-SEM) corresponding to 20.7+/-6.3 pg/IEQ. After culture ATP content increased to 265.5+/-113.3 pg/microg IP (204.2+/-41.5%) corresponding to 43.7+/-15.3 pg/IEQ (216.1+/-34.9%; p<0.05). The coefficient of variation was 129.5%, 96.5% (fresh) and 135.0%, 111.0% (cultured) for ATP/microg IP and ATP/IEQ, respectively. The present data show that: (1) the ATP content of freshly isolated human islets varies enormously; (2) intraislet ATP levels increase significantly during 22 degrees C culture suggesting that the capacity to produce ATP is maintained despite hypothermic environment. More data are necessary to clarify the relevance of intraislet ATP content for graft function and survival after islet transplantation.

Adenosine Triphosphate↗