Impact of COVID-19 lockdown on glucose control of elderly people with type 2 diabetes in Italy

AIMS

to evaluate the effect of home confinement related to COVID-19 lockdown on metabolic control in subjects with T2DM in Italy.

METHODS

we evaluated the metabolic profile of 304 individuals with T2DM (65% males; age 69 ± 9 years; diabetes duration 16 ± 10 years) attending our Diabetes Unit early at the end of lockdown period (June 8 to July 7, 2020) and compared it with the latest one recorded before lockdown.

RESULTS

There was no significant difference in fasting plasma glucose (8.6 ± 2.1 vs 8.8 ± 2.5 mmol/L; P = 0.353) and HbA1c (7.1 ± 0.9 vs 7.1 ± 0.9%; P = 0.600) before and after lockdown. Worsening of glycaemic control (i.e., ΔHbA1c ≥ 0.5%) occurred more frequently in older patients (32.2% in > 80 years vs 21.3% in 61-80 years vs 9.3% in < 60 years; P = 0.05) and in insulin users (28.8 vs 16.5%; P = 0.012). On multivariable analysis, age > 80 years (OR 4.62; 95%CI: 1.22-16.07) and insulin therapy (OR 1.96; 95%CI: 1.10-3.50) remained independently associated to worsening in glycaemic control.

CONCLUSIONS

Home confinement related to COVID-19 lockdown did not exert a negative effect on glycaemic control in patients with T2DM. However, age and insulin therapy can identify patients at greatest risk of deterioration of glycaemic control.

Type 1 diabetes and COVID-19: The "lockdown effect"

AIMS

The aim of this study was to evaluate the effect the lockdown imposed during COVID-19 outbreak on the glycemic control of people with Type 1 diabetes (T1D) using Continuous (CGM) or Flash Glucose Monitoring (FGM).

MATERIALS AND METHODS

We retrospectively analyzed glucose reading obtained by FGM or CGM in T1D subjects. Sensor data from 2 weeks before the lockdown (Period 0, P₀), 2 weeks immediately after the lockdown (period 1, P₁), in mid-lockdown (Period 2, P₂) and immediately after end of lockdown (Period 3, P₃) were analyzed.

RESULTS

The study included 63 T1D patients, (FGM: 52, 82%; CGM:11, 18%). Sensor use (91%) were slightly reduced. Despite this reduction, Time in Range increased in P₁ (62%), P₂ (61%) and P₃ (62%) as compared to P₀ (58%, all p < 0.05 or less) with concomitant reduction in the Time Above Range (P₀: 38%; P₁: 34%, P₂: 34%, P₃: 32%, all p < 0.05 or less vs. P₀). Average glucose and GMI improved achieving statistical difference in P₃ (165 vs. 158 mg/dl, p = 0.040 and 7.2% (55 mmol/mol) vs. 7.0% (53 mmol/mol), p = 0.016) compared to P0. Time Below Range (TBR) and overall glucose variability remained unchanged. Bi-hourly analysis of glucose profile showed an improvement particularly in the early morning hours.

CONCLUSIONS

In T1D subjects with good glycemic control on CGM or FGM, the lockdown had no negative impact. Rather a modest but significant improvement in glycemic control has been recorded, most likely reflecting more regular daily life activities and reduces work-related distress.

Hyperglycemia at Hospital Admission Is Associated With Severity of the Prognosis in Patients Hospitalized for COVID-19: The Pisa COVID-19 Study

OBJECTIVE

To explore whether at-admission hyperglycemia is associated with worse outcomes in patients hospitalized for coronavirus disease 2019 (COVID-19).

RESEARCH DESIGN AND METHODS

Hospitalized COVID-19 patients (N = 271) were subdivided based on at-admission glycemic status: 1) glucose levels <7.78 mmol/L (NG) (N = 149 [55.0%]; median glucose 5.99 mmol/L [range 5.38-6.72]), 2) known diabetes mellitus (DM) (N = 56 [20.7%]; 9.18 mmol/L [7.67-12.71]), and 3) no diabetes and glucose levels ≥7.78 mmol/L (HG) (N = 66 [24.3%]; 8.57 mmol/L [8.18-10.47]).

RESULTS

Neutrophils were higher and lymphocytes and PaO₂/FiO₂ lower in HG than in DM and NG patients. DM and HG patients had higher D-dimer and worse inflammatory profile. Mortality was greater in HG (39.4% vs. 16.8%; unadjusted hazard ratio [HR] 2.20, 95% CI 1.27-3.81, P = 0.005) than in NG (16.8%) and marginally so in DM (28.6%; 1.73, 0.92-3.25, P = 0.086) patients. Upon multiple adjustments, only HG remained an independent predictor (HR 1.80, 95% CI 1.03-3.15, P = 0.04). After stratification by quintile of glucose levels, mortality was higher in quintile 4 (Q4) (3.57, 1.46-8.76, P = 0.005) and marginally in Q5 (29.6%) (2.32, 0.91-5.96, P = 0.079) vs. Q1.

CONCLUSIONS

Hyperglycemia is an independent factor associated with severe prognosis in people hospitalized for COVID-19.

Microvascular complications burden (nephropathy, retinopathy and peripheral polyneuropathy) affects risk of major vascular events and all-cause mortality in type 1 diabetes: a 10-year follow-up study

Background

Microvascular complications (MC) have been claimed to increase the risk for cardiovascular disease in diabetic subjects. However, the effect of MC burden on the risk of major vascular outcomes and all-cause mortality in type 1 diabetes is still poorly explored. We evaluated the relationship between microvascular complications burden and incidence of major cardiovascular events and all-cause mortality in subjects with type 1 diabetes.

Methods

We recruited 774 participants with type 1 diabetes in a single-center observational study over a follow-up of 10.8 ± 2.5 years. Hazard ratios (HR) for cardiovascular outcomes and all-cause death associated with microvascular complications were determined by unadjusted and adjusted Cox regression analysis.

Results

Out of 774 individuals, 54.9% had no-MC, 32.3% 1 MC, 9.7% 2 MC and 3.1% 3 MC. A total of 54 deaths (7.0%) occurred. Death rate increased from no-MC 2.1% (Ref) to 1 MC 7.2% (HR 3.54 [95% CI 1.59–7.87]), 2 MC 14.7% (HR 6.41 [95% CI 2.65–15.49]) and 3 MC 66.7% (HR 41.73 [95% CI 18.42–94.57], p < 0.0001). After adjustments, HRs were: 1 MC 2.05 (95% CI 0.88–4.76), 2 MC 1.98 (95% CI 0.75–5.21), 3 MC 7.02 (95% CI 2.44–20.20, p = 0.002). Forty-nine subjects (6.7%) had at least one cardiovascular event, and cumulative incidence went from no-MC 2.2% (Ref) to 1 MC 5.0%; (HR 2.27 [95% CI 0.96–5.38]), 2 MC 26.8% (HR 12.88 [95% CI 5.82–28.50]) and 3 MC 40.9% (HR 29.34 [95% CI 11.59–74.25], p < 0.0001). Upon adjustments, HRs were: 1 MC 1.59 (95% CI 0.65–3.88), 2 MC 4.33 (95% CI 1.75–10.74), 3 MC 9.31 (95% CI 3.18–27.25, p < 0.0001). Thirty-five individuals (4.8%) had at least one coronary event, which cumulative incidence increased with MC burden (p < 0.0001).

Conclusions

In type 1 diabetes, microvascular complications burden increases in an independent dose-dependent manner the risk of major cardiovascular outcomes and all-cause mortality. The presence and number of microvascular complications should be considered in stratifying overall cardiovascular risk in type 1 diabetes.

Results of pancreas transplantation alone with special attention to native kidney function and proteinuria in type 1 diabetes patients

We report on our single-center experience with pancreas transplantation alone (PTA) in 71 patients with type 1 diabetes, and a 4-year follow-up. Portal insulin delivery was used in 73.2% of cases and enteric drainage of exocrine secretion in 100%. Immunosuppression consisted of basiliximab (76%), or thymoglobulin (24%), followed by mycophenolate mofetil, tacrolimus, and low-dose steroids. Actuarial patient and pancreas survival at 4 years were 98.4% and 76.7%, respectively. Relaparatomy was needed in 18.3% of patients. Restored endogenous insulin secretion resulted in sustained normalization of fasting plasma glucose levels and HbA1c concentration in all technically successful transplantations. Protenuria (24-hour) improved significantly after PTA. Renal function declined only in recipients with pretransplant glomerular filtration rate (GFR) greater than 90 ml/min, possibly as a result of correction of hyperfiltration following normalization of glucose metabolism. Further improvements were recorded in several cardiovascular risk factors, retinopathy, and neuropathy. We conclude that PTA was an effective and reasonably safe procedure in this single-center experience.

Pancreas transplant alone has beneficial effects on retinopathy in type 1 diabetic patients

AIMS/HYPOTHESIS

The effects of successful pancreas transplant alone (PTA) on chronic complications of diabetes, in particular diabetic retinopathy, remain disputed. We prospectively studied the course of diabetic retinopathy in PTA recipients and in non-transplanted (non-PTA) type 1 diabetic patients.

METHODS

The PTA and non-PTA groups consisted respectively of 33 (follow-up: 30 +/- 11 months) and 35 patients (follow-up: 28 +/- 10 months). Best corrected visual acuity, slit lamp examination, intraocular pressure measurement, ophthalmoscopy, retinal photographs, and in selected cases angiography were performed. Diabetic retinopathy and its improvement/deterioration were assessed according to criteria proposed by the Eurodiab Study.

RESULTS

At baseline, 9% of PTA and 6% of non-PTA patients had no diabetic retinopathy, 24 and 29% had non-proliferative diabetic retinopathy (NPDR), whereas 67 and 66% had laser-treated and/or proliferative diabetic retinopathy (LT/PDR), respectively. No new case of diabetic retinopathy occurred in either group during follow-up. In the NPDR PTA group, 50% of patients improved by one grading, and 50% showed no change. In the LT/PDR PTA, stabilisation was observed in 86% of cases, whereas worsening of retinopathy occurred in 14% of patients. In the NPDR non-PTA group, diabetic retinopathy improved in 20% of patients, remained unchanged in 10%, and worsened in the remaining 70%. In the LT/PDR non-PTA group, retinopathy did not change in 43% and deteriorated in 57% of patients. Overall, the percentage of patients with improved or stabilised diabetic retinopathy was significantly higher in the PTA group. No differences were found between the two groups with regard to cataract lesions and intraocular pressure values.

CONCLUSIONS/INTERPRETATION

Despite a relatively short follow-up, our study shows that successful PTA can positively affect the course of diabetic retinopathy.

Neoral versus prograf in simultaneous pancreas-kidney transplantation with portal venous drainage: three-year results of a single-center, open-label, prospective, randomized pilot study

BACKGROUND

The preferential use of tacrolimus (Prograf) over cyclosporine microemulsion (Neoral) in simultaneous pancreas-kidney transplantation (SPKTx) is mainly based on historical, retrospective studies. We herein report the 3-year results of a single-center, prospective, randomized comparison of the two calcineurin inhibitors in the setting of mycophenolate mofetil (MMF)-based immunosuppression and portal drainage of pancreas allografts.

METHODS

Between May 2001 and August 2004, 47 SPKTx recipients who were stratified by recipient sex, were alternatively assigned to treatment with Neoral (n = 22) or Prograf (n = 25). Concurrent immunosuppression included induction treatment with basiliximab and maintenance with MMF and steroids.

RESULTS

After a median follow-up of 24.0 months, all patients remained in the study arm into which they were initially enrolled. No pancreas rejection episode was observed. One acute kidney rejection was recorded in the Neoral arm (4.5%) as compared with 7 (28.0%) including one steroid-resistant episode, in the Prograf arm (P = .03). The cumulative incidence of adverse events was 31.8% (n = 7) in the Neoral arm compared with 92.0% (n = 23) in the Prograf arm (P < .0001). One patient died in each study arm. Patient, pancreas, and kidney survivals overlapped at 1- and 3-years posttransplant, namely all 95.4% for the Neoral arm compared with 95.8%, 91.8%, and 95.8%, respectively, for the Prograf arm (P > .05).

CONCLUSIONS

We conclude that in MMF-based immunosuppression there is no convincing evidence that Prograf should be preferred to Neoral in SPKTx.

The beneficial effects of pancreas transplant alone on diabetic nephropathy

OBJECTIVE

Pancreas transplant alone can be effective in significantly improving the quality of life of type 1 diabetic patients, and it can also eliminate acute diabetes complications, such as hypoglycemic and/or hyperglycemic episodes. The effects of pancreas transplant alone on long-term complications of diabetes, including nephropathy, are still not settled. We evaluated whether restoration of long-lasting normoglycemia by pancreas transplant alone might have beneficial action on diabetic nephropathy.

RESEARCH DESIGN AND METHODS

A total of 32 type 1 diabetic patients were evaluated before and 1 year after successful pancreas transplant alone, together with 30 matched nontransplanted type 1 diabetic subjects. Several metabolic and kidney function parameters were measured, including plasma glucose, glycohemoglobin (A1C), C-peptide, plasma lipids, blood pressure, creatinine, creatinine clearance, and urinary protein excretion.

RESULTS

Pancreas transplant alone restored sustained normoglycemia, without exogenous insulin administration, and improved plasma lipid levels. Blood pressure decreased significantly. Creatinine concentrations and clearances did not differ before and after transplantation. Urinary protein excretion decreased significantly after pancreas transplant alone, with four microalbuminuric and three macroalbuminuric patients who became normoalbuminuric. None of these changes occurred in the nontransplanted group.

CONCLUSIONS

Successful pancreas transplant alone, through restoration of sustained normoglycemia, improves diabetic nephropathy in type 1 diabetic patients.

Effects of pancreas-kidney transplantation on diabetic retinopathy

The effects of pancreas transplantation (PTx) on diabetic retinopathy (DR) are still debated. We studied the course of DR in 48 patients (age: 40 +/- 7 years; males/females 26/22, body mass index (BMI): 23.0 +/- 2.4 kg/m2, duration of diabetes: 24 +/- 8 years) bearing a successful PTx (combined with a kidney). Follow-up ranged 6-60 months (median: 17 months). Before transplantation, according to the Eurodiab Study classification, 12 patients (25%) had nonproliferative retinopathy (NPDR; mild, moderate or severe), and 36 patients (75%) had laser-treated and/or proliferative retinopathy (LT/PDR). During the follow-up, in the NPDR group improvement/deterioration was defined as regression/progression to a lower/higher retinopathy grade; in the LT/PTD group, stabilization was defined as no new neo-vessel formation or development of new lesions requiring laser-treatment. In the NPDR group, five (41.7%) patients improved of one or more lesion grading, three (25%) patients showed no change, and four (33.3%) patients progressed of one grade. In the LT/PDR group, the post-transplant data were: stabilization in 35 (97%) patients, and worsening in one (3%) patient. The number of improved/stabilized patients was significantly higher in the transplanted than in a control group of nontransplanted type 1 diabetic patients. In conclusion, despite a relatively short follow-up period, successful PTx in our cohort of patients was associated with improvement and/or stabilization of DR in the majority of recipients.

Retroperitoneal pancreas transplantation with portal-enteric drainage

BACKGROUND

Portal-enteric drainage (PED) is the latest refinement in the surgical technique for pancreas transplantation (PTx). We herein describe the results of a modified technique for PED that places the pancreas in a totally retroperitoneal position.

METHODS

Between April 2001 and June 2003, 79 PTx were performed using a retroperitoneal PED technique.

RESULTS

No graft was lost due to surgical complications and the relaparotomy rate was 11.4%. Mean hospital stay averaged 25.9 days (+/-14.4 days) with a 30-day readmission rate of 12.7%. One graft was lost due to delayed (6 months) arterial thrombosis and three to acute rejection. The overall 1-year patient and graft survivals were 98.7% and 93.7%, respectively.

CONCLUSIONS

Our data confirm that PED of pancreas grafts is associated with low morbidity and mortality rates. Whether retroperitoneal graft placement has actual advantages over the "classical" intraperitoneal position remains to be ascertained.

Single-Center, open, prospective, randomized pilot study comparing cyclosporine versus tacrolimus in simultaneous Pancreas-Kidney transplantation

BACKGROUND

Although tacrolimus (Prograf) is the calcineurin inhibitor usually employed in simultaneous pancreas-kidney transplantation (SPKTx), no prospective randomized studies have compared its efficacy to cyclosporine (Neoral), when either drug is used in combination with mycophenolate mofetil (MMF) and the pancreas is drained into the portal vein.

METHODS

Between May 2001 and June 2003, 16 SPKTx recipients were randomized to be prescribed Neoral and 17 Prograf in addition to basiliximab, steroids, and MMF. All pancreata were drained into the portal vein.

RESULTS

After a median follow-up of 15.6 months, six kidney acute rejection episodes were observed with Prograf (36.5%; one steroid-resistant) and one Neoral (n = 1, 6.2%; P =.04). No pancreas rejection episode was recorded. Two infections occurred in two recipients from each group. No major adverse events were noted other than a severe hematological toxicity (Prograf). Metabolic parameters were equivalent in the two groups, save for higher total cholesterol (212 +/- 39 mg/dL vs 173 +/- 23 mg/dL; P =.008), LDL (129 +/- 33 mg/dL vs 101 +/- 21 mg/dL; P =.029), and triglyceride (191 +/- 86 mg/dL vs 126 +/- 40 mg/dL; P =.028), values with Neoral, although the same differences were already present at baseline. One recipient (Neoral) died with functioning grafts. Patient, pancreas, and kidney survival rates were all 94% for Neoral versus 100% for Prograf.

CONCLUSIONS

Although a larger series and a longer follow-up are needed, Neoral and Prograf used in combination with MMF seem to achieve equivalent success rates among primary SPKTx when the pancreas is drained into the portal vein.

Solitary pancreas transplantation: preliminary findings about early reduction of proteinuria in incipient or evident diabetic type I nephropathy

OBJECTIVE

Our work was aimed to evaluate the precocious reduction of proteinuria in patients suffering from diabetes mellitus type 1 with incipient and evident nephropathy after isolated pancreas transplantation (PTA).

MATERIALS AND METHODS

From December 2000 to March 2003, we followed 24 PTA grafts in 24 patients with diabetes mellitus type 1 (mean age 37.8 years; mean duration of diabetes 24.8 years). The pancreas was transplanted with portal-enteric drainage in 23 patients and systemic-enteric in 1 patient. The immunosuppressive therapy used basilixmab induction and tacrolimus, mycophenolate mophetil (MMF), and low dose steroid maintenance therapy. The renal function, proteinuria, and the glucose metabolic parameters were evaluated before and during the following months after transplant.

RESULTS

All patients are alive and twenty-one have a well-functioning pancreas with three grafts lost. All patients had persistence of normal renal function. Before transplantation 12 patients displayed proteinuria that was clearly reduced in 11 and gone in three patients, all of whom were insulin-independent.

CONCLUSIONS

TPA seems to reduce, and in some cases to regress, the proteinuria associated with early diabetic nephropathy.

Pancreas transplant alone

Pancreas transplant alone (PTA) represents a growing proportion of overall pancreas transplantations, with 1-year patient and graft survivals of almost 100% and higher than 80%, respectively. PTA can restore normoglycemia without exogenous insulin administration and eliminate acute diabetic complications. In our series of 28 PTA, performed with portal-enteric drainage, 2-year patient and pancreas survivals were 100% and 87%, respectively. In patients with successful transplantation, rapid normalization of blood glucose level and HbA1c concentration was observed, due to restored endogenous insulin secretion. Several classical cardiovascular risk factors were measured before and after transplant, with significant improvements shortly after transplantation. Diabetic retinopathy improved in 58.8% of examined eyes, stabilized in 35.3%, and worsened in 5.9%. In conclusion, PTA represents a clinically relevant option for patients with type 1 diabetes without advanced renal disease. It restores normoglycemia in the vast majority of patients and seems to have a positive impact on late diabetic complications.

Echocardiographic evaluation in type 1 diabetic patients on waiting list for isolated pancreas or kidney-pancreas transplantation

Type 1 diabetic patients may display abnormalities of left ventricular geometry and systolic and diastolic function. Patients on the waiting list for solitary pancreas or kidney-pancreas transplantation were evaluated by Doppler echocardiography to assess left ventricular geometry and systolic and diastolic function, and correlate these parameters with clinical characteristics. We evaluated 78 patients including 45 men with an overall mean age of 39.5 +/- 7.2 years and a disease duration of 24 +/- 9.8 years. Among these 78 patients, 13 showed isolated retinopathy, 9 isolated arterial hypertension, 45 concomitant retinopathy and hypertension and overt nephropathy, while 11 were free of complications. The results of our study showed an increased left ventricular mass and abnormal diastolic function among patients with simultaneous target organ complications and with hypertension, as has been reported in many previous studies. In contrast study patients with no complications showed normal left ventricular structure and function. This finding conflicts with data from several reports in the medical literature in which diastolic impairment was present in type 1 diabetic patients at an early stage of disease and with no evident microvascular and macrovascular complications.

Reducing insulin resistance with metformin: the evidence today

Insulin resistance, defined as the inability of insulin to exert a normal biological action at the level of its target tissues, is one of the principal pathogenetic defects of type 2 diabetes. Metformin, the most widely-prescribed insulin-sensitizing agent in current clinical use, improves blood glucose control mainly by improving insulin-mediated suppression of hepatic glucose production, and by enhancing insulin-stimulated glucose disposal in skeletal muscle. Experimental studies show that metformin-mediated improvements in insulin sensitivity may be associated with several mechanisms, including increased insulin receptor tyrosine kinase activity, enhanced glycogen synthesis, and an increase in the recruitment and activity of GLUT4 glucose transporters. In adipose tissue, metformin promotes the re-esterification of free fatty acids and inhibits lipolysis, which may indirectly improve insulin sensitivity through reduced lipotoxicity. The improved glycaemia with metformin is not associated with increased circulating levels of insulin, and the risk of hypoglycaemia with metformin is minimal. The therapeutic profile of metformin supports its use for the control of blood glucose, in diabetic patients and for the prevention of diabetes in subjects with impaired glucose tolerance. Moreover, the improvement by metformin of cardiovascular risk factors associated with the dysmetabolic syndrome may account for the significant improvements in macrovascular outcomes observed in the UK Prospective Diabetes Study.

Pancreas transplant alone determines early improvement of cardiovascular risk factors and cardiac function in type 1 diabetic patients1

BACKGROUND

The effects of pancreas transplant alone (PTA) on cardiovascular risk factors (CRF) and cardiac function in type 1 diabetes mellitus (T1DM) patients are still unsettled.

METHODS

We studied 13 T1DM patients who received PTA with portal drainage and 11 matched control patients. Parameters of glucose and lipid metabolism and several additional classic CRF were assessed before and up to 6 months posttransplant. Cardiac morphology and function were assessed by Doppler echocardiographic examination.

RESULTS

Insulin independence was promptly achieved and then maintained after PTA. Total and low-density lipoprotein cholesterol levels were significantly lower after transplantation, whereas high-density lipoprotein cholesterol and triglyceride concentrations did not change. Both systolic and diastolic blood pressure values and fibrinogen levels improved significantly. In addition, PTA determined a significant amelioration of several morphologic and functional cardiac indices. None of the measured parameters changed in the control patients.

CONCLUSIONS

PTA with portal drainage induces an early improvement of CRF and ameliorates cardiac function in patients with T1DM.

Dissociation between carotid artery lesions and lipid parameters in recipients of successful kidney graft

BACKGROUND

The relationships between lipid levels and atherosclerotic lesions of carotid arteries in kidney graft recipients are still unclear.

METHODS

We evaluated carotid morphology in 53 recipients of functioning renal transplantation, and studied the relationship of carotid artery wall lesions with relevant clinical and laboratory risk factors for cardiovascular disease. The patients were on stable, cyclosporine-based immunosuppressive therapy.

RESULTS

The main clinical characteristics of patients were: age, 46.5 +/- 10.1 years; males/females, 40/13; body mass index, 25.8 +/- 4.4 kg/m2; duration of transplantation, 43 +/- 52 months. Ultrasonographic scanning of carotid arteries showed the presence of lesions (intimal-media thickness and/or plaque) in 28 patients (52.8%). These recipients differed from patients without carotid lesions in terms of age (50.4 +/- 9.0 vs 42.2 +/- 9.7 years, p < 0.01) and duration of pre-transplant dialysis (4.6 +/- 3.4 vs 2.3 +/- 1.9 years, p < 0.01), whereas no statistically significant difference was observed as for total cholesterol (230 +/- 44 vs 235 +/- 35 mg/dl), LDL-cholesterol (142 +/- 32 vs 143 +/- 30 mg/dl), HDL-cholesterol (52 +/- 12 vs 58 +/- 20 mg/dl) and triglycerides (178 +/- 94 vs 167 +/- 89 mg/dl). The percentage of post-transplant diabetes was 3-fold higher in patients with carotid lesions (25 vs 8%). No difference was observed as for the following parameters: body mass index, duration of transplantation, fibrinogen levels, DDimer concentrations, reactive C-protein values, prevalence of hypertension, percentage of smokers vs non-smokers.

CONCLUSIONS

The present study supports the view that carotid artery lesions in kidney graft recipients on stable, cyclosporine-based immunosuppressive therapy may not be related to circulating lipid values.

Lymphokine release from human lymphomononuclear cells after co-culture with isolated pancreatic islets: effects of islet species, long-term culture, and monocyte-macrophage cell removal

This study evaluated the release of Th1 and Th2 cytokines from human lymphomononuclear cells (LMC) in response to purified human (HI) or bovine (BI) islets, and the role of long-term (3-4 weeks) islet culture and removal of monocyte-macrophage cells. The results showed that HI and BI caused a similar increase of the release of gamma interferon (IFN), IL-2 and IL-6 from LMC, whereas BI had a more marked effect than HI on IL-10 release. Culturing the islets had possible positive effects (reduction of IFN and IL-2), but also potentially negative effects (increase of TNF). Removal of monocyte-macrophage cells determined a significant reduction of IL-6, IL-10 and TNF production in response to xeno-islets.

The biguanide compound metformin prevents desensitization of human pancreatic islets induced by high glucose

Pancreatic islet desensitization by high glucose concentrations is a temporary and reversible state of beta-cell refractoriness to glucose (and possibly other secretagogues), due to repeated or prolonged pre-exposure to increased glucose concentrations. We evaluated whether the oral antidiabetic agent metformin affects this phenomenon in isolated, human pancreatic islets, and whether the possible effects of the biguanide are influenced by the presence of a sulphonylurea, glyburide. Islets prepared from five human pancreases were incubated for 24 h in M199 culture medium containing either 5.5 or 22.2 mmol/l glucose, with or without a therapeutic concentration (2.4 microg/ml) of metformin. Then, the islets were challenged with either 3.3 mmol/l glucose, 16.7 mmol/l glucose, or 3.3 mmol/l glucose + 10 mmol/l arginine, and insulin release was measured. After incubation in the absence of metformin, the human islets exposed to 22.2 mmol/l glucose showed no significant increase in insulin release when challenged with 16.7 mmol/l glucose (confirming that hyperglycemia desensitizes pancreatic beta-cells). In the presence of metformin, the islets fully maintained the ability to significantly increase their insulin release in response to glucose, even when previously exposed to 22.2 mmol/l glucose. No major effect on arginine-induced insulin release was observed, whatever the culture conditions. The protective action of metformin was observed also when glyburide was present in the incubation medium, whereas the sulphonylurea alone did not affect insulin release from the islets previously exposed to high glucose concentrations. These in vitro results suggest that metformin can prevent the desensitization of human pancreatic islets induced by prolonged exposure to increased glucose concentrations.

Effects of glibenclamide and metformin (alone or in combination) on insulin release from isolated human pancreatic islets

Isolated human pancreatic islets were prepared by collagenase digestion and density gradient purification, and the effects of glibenclamide (0.5 and 5.0 mumol/l) and metformin (20 and 200 mumol/l), alone or in combination, on insulin release were evaluated at varying glucose concentrations. At 3.3 mmol/l glucose level, the addition of 5.0 mumol/l glibenclamide or 5.0 mumol/l glibenclamide plus 200 mumol/l metformin caused a significant increase of insulin release, compared with glucose alone. At 16.7 mmol/l glucose concentration, a significant increase of insulin secretion, compared with glucose alone, was produced by the addition of either 5.0 mumol/l glibenclamide, 200 mumol/l metformin, or both 5.0 mumol/l glibenclamide and 200 mumol/l metformin. The effect of the combination of the two drugs was significantly higher than that with either drug used alone. Thus, glibenclamide was shown to have an insulinotropic effect on human islets at both low and high glucose concentrations, and metformin at high glucose concentrations. A possible synergistic effect of glibenclamide and metformin at high glucose concentrations is also suggested.

Long-term survival and function of isolated bovine pancreatic islets maintained in different culture media

Bovine islets are being evaluated for their potential in transplantation studies. We studied the recovery, morphology, and function of purified bovine islets cultured up to 4 weeks under varying conditions. Approximately 60% of the initial islet mass could be recovered after 4 weeks at 37 degrees C in CMRL 1066 or M 199 culture medium, and the cultured islets were well preserved histologically and viable both in vitro and in vivo. On the other hand, culture with RPMI 1640 caused disaggregation of the islets within a few days, with altered in vitro viability. Thus, culturing purified bovine islets with appropriate media is a suitable procedure to maintain islet mass, morphology, and function in the long term.

Lymphokine release during co-culture of human lympho-mononuclear cells and fresh or cultured human, porcine and bovine pancreatic islets

In this study we evaluated whether isolated human (HI), porcine (PI) and bovine (BI) islets, either fresh (Fr) or cultured for 4 weeks (4 w) affect cytokine release from human lymphomononuclear cells (LMC) differently. We prepared LMC from peripheral blood by density gradient purification and co-cultured 1 x 10(6) LMC for 24 h with 100 hand-picked islets, either within 48 h of isolation or after culture for 4 weeks. Soluble interleukin-2 receptor (IL-2R), interferon-gamma (IFN), interleukin-4 (IL-4) and interleukin-10 (IL-10) were measured by sandwich enzyme-linked immunoadsorbent assay. Compared with controls (Ctrl, LMC without islets), Fr-HI, Fr-PI and Fr-BI caused a similar increase of IL-2R and IFN release, whereas 4 w-HI and 4 w-BI did not lead to any significant production of these two cytokines. IL-10 concentrations increased with Fr-PI and Fr-BI, but not with Fr-HI, and no major effect of the 4-week culture was seen. IL-4 levels were below the detection limit of the method used in these experiments. Thus, fresh allo- and xeno-islets caused a similar increase of the release of cytokines known to be markers of Th1 activation, whereas the release of IL-10, a marker of Th2 activation, increased with xeno-, but not with allo-islets; culturing the islets for 4 weeks decreased Th1, but not Th2 activation.

Characterization of peripheral benzodiazepine receptors in purified large mammal pancreatic islets

In this work, we evaluated the biochemical properties of peripheral benzodiazepine receptors (PBRs) in the porcine endocrine pancreas and their role in insulin release. Binding of [3H]1-(2-chlorophenyl-N-methyl-1-methyl-propyl)-3-isoquinolinecarboxa mide ([3H]PK-11195), a specific ligand of PBRs, to islet membranes was saturable and Scatchard's analysis of saturation curve demonstrated the presence of a single population of binding sites, with a dissociation constant (Kd) value of 4.75 +/- 0.70 nM and a maximum amount of specifically bound ligand (Bmax) of 4505 +/- 502 fmol/mg of proteins. The pharmacological profile of PBRs was determined as the ability of PK-11195 and several benzodiazepine compounds to displace [3H]PK-11195 from these binding sites. The rank order of potency yielded the following affinity results: PK-11195 > 7-chloro-1,3-dihydro-1-methyl-5-(p-chlorophenyl)-2H-1,4-benzodiazepine-2 -on (Ro 5-4864) > diazepam > or = flunitrazepam >> flumazenil. Secretion studies demonstrated that PK-11195 (1 and 10 microM) and Ro 5-4864 (10 and 50 microM) significantly potentiated insulin secretion from freshly isolated porcine islets at 3.3 mM glucose. This potentiating effect was not observed at 16.7 mM glucose concentration nor by the addition of clonazepam. These results show the presence of PBRs in purified porcine pancreatic islets and suggest an implication of PBRs in the mechanisms of insulin release.

Prolonged survival of discordant porcine islet xenografts

Purified porcine islets were prepared by collagenase digestion and density gradient purification, and transplanted under the kidney capsule of C57B/B6 mice with streptozotocin-induced diabetes which were receiving varying temporary immunosuppressive therapies. Islets that had been cultured for 1 day at 37 degree C were rejected after : 9+/-0.1 (mean+/-SE) days in control mice: 14+/-3 days in mice receiving mouse antilymphocyte serum (MLS) plus porcine antilymphocyte serum (PLS) on day of transplant (day 0); 43+/-6 days in mice treated for 1 week with anti-CD4 antibody (aCD4); 36+/-4 days in mice given aCD4 for 1 week plus PLS on days 0 and 7; 47+/-3 days in mice treated with aCD4 for 1 week plus MLS and PLS on day 21. Porcine islet survival in these latter three groups was significantly (P<0.01) and similarly longer than in the control and MLS plus PLS groups. Then, we transplanted islets that had been either cultured at 24 degrees C for 7 days or cryopreserved into 7-day aCD4-treated mice, to evaluate whether low temperature culture or the freezing-thawing procedure could affect survival. Neither 7-day, low temperature culture (mean survival time: 37+/-2 days) nor cryopreservation (mean survival time: 39+/-2 days) prolonged islets function further. Thus, the present study demonstrates that prolonged survival can be achieved with discordant porcine islet xenografts, and shows the greater efficacy of aCD4 treatment, which was not improved by additional immunosuppressive therapies we tested, nor by culture or cryopreservation of the islets.

Cryopreservation of purified bovine islets of Langerhans

In this study, bovine islets were isolated by collagenase digestion and density gradient purification, equilibrated stepwise with 3 M dimethylsulfoxide at 24 degrees C, nucleated at -150 degrees C, slow cooled at 0.25 degrees C/min down to -40 degrees C, and finally stored at -150 degrees C. After variable periods of time, the islets were quickly thawed at 37 degrees C, and dimethylsulfoxide was removed by 0.75 M sucrose. Postthawing recovery was 86 +/- 6% islet equivalents. Histology confirmed the identity and morphological integrity of the islets. Insulin release from the frozen-thawed islets was 0.13 +/- 0.03 microU/is/min at 3.3 mmol/L glucose and increased significantly (0.27 +/- 0.04 microU/is/min, P < 0.05) at 25 mmol/L glucose. Encapsulated, cryopreserved islets reversed hyperglycemia in diabetic mice after 6-8 days following implantation. Therefore, the method described in this paper permitted successful cryopreservation of bovine islets of proven in vitro and in vivo viability.