Activity In Diabetic Patients Research Articles

Complement mediated bactericidal activity and humoral immune response in type 2 diabetes mellitus

Since diabetic patients suffer from protracted infections, the aim of this study was to determine the functions of serumcomplement and its relationship with immunoglobulin profiles in patients with type 2 diabetes mellitus (DM). A total of 55DM patients and 54 healthy volunteers were included in this study. Serum IgG was measured by nephelometry,complement components C3 and C4, and IgA were measured by immunoturbidometric methods. The bactericidalactivities of complement from fresh serum and complement-inactivated serum were assessed against Escherichia coliDH5α cells using the standard plate count method. In the DM patients, IgG (p<0.001), IgA (p<0.02) and complementcomponent C4 (p<0.001) were found to be significantly elevated whereas the levels of C3 were slightly lowered (p<0.4).The complement mediated bactericidal activity in diabetic patients was significantly lower than the controls (p<0.01).In contrast, while the serum complements were inactivated by heat treatment, the DM patients had significantly higher(p<0.01) bactericidal activity associated with heat-stable immune effector molecules, possibly elevated levels of serumIgG and IgA. The results of this study indicate that serum complement mediated bactericidal activity was impaired in type 2diabetic patients, which might be a cause for delayed wound healing and repeated infections. (Int J Diabetes Metab 14: 92-97,2006)

Coagulation and Fibrinolysis Parameters in Type 2 Diabetic Patients with and without Diabetic Vascular Complications

Objectives: To investigate the markers of endogenous coagulation/fibrinolysis and vascular endothelial cell function, and to assess the relationships between hemostatic parameters and diabetic vascular complications in type 2 diabetic patients. Materials and Methods: Coagulation and fibrinolysis parameters were measured in 92 type 2 diabetic patients (43 male, 49 female, mean age 50.1 ± 13.4 years) with (n = 44) and without (n = 48) vascular diabetic complications, and in 40 nondiabetic healthy subjects (20 male, 20 female, mean age 49.8 ± 15.1 years). Common lipid parameters were also measured. Results: The plasma levels of fibrinogen, antithrombin III (AT III), plasminogen activator inhibitor-1 (PAI-1), von Willebrand factor (vWF) activity and prothrombin time were found to be significantly increased in the type 2 diabetic patients compared with the healthy subjects. Glycosylated hemoglobin lc was inversely correlated with plasma protein S and activated prothrombin time. Protein C and S activities were positively correlated with plasma vWF activity, and were negatively correlated with plasma t-PA levels. vWF activity was negatively correlated with plasma t-PA levels. AT III levels were positively correlated with plasma total cholesterol levels, plasma low density lipoprotein cholesterol levels, plasma triglycerides and D-dimer levels. Plasma PAI-1 levels and factor V activity in diabetic patients with microvascular complications were significantly higher than those of the diabetic patients without microvascular complications. The plasma PAI-1 and platelet count were increased in patients with diabetic retinopathy compared with the diabetic patients without retinopathy. Plasma PAI-1 levels and factor VII activity were significantly higher in the diabetic patients with nephropathy than in diabetic patients without nephropathy. Plasma concentrations of fibrinogen and PAI-1 were significantly higher in the diabetic patients with neuropathy than the diabetic patients without neuropathy. Conclusions: The data demonstrated that patients with type 2 diabetes mellitus had a hypercoagulable state and hypofibrinolysis, thereby indicating that activation of coagulation with a reduced fibrinolytic activity may contribute to the increased risk of vascular disease in type 2 diabetic patients.

Protective Effect of Paraoxonase Activity in High-Density Lipoproteins against Erythrocyte Membranes Peroxidation: A Comparison between Healthy Subjects and Type 1 Diabetic Patients

High-density lipoproteins (HDL) plays a key role in the protection against oxidative damage of lipoprotein and biological membranes. The aim of the present study was to investigate the relationship between the antioxidant role of HDL and the HDL-paraoxonase (PON) activity in healthy subjects and in type 1 diabetic patients. Moreover, the ability of HDL of controls and diabetic patients to protect and/or repair biological membranes from oxidative damage was studied. HDL were isolated from 31 type 1 diabetic patients and 31 sex- and age-matched healthy subjects and immediately used to evaluate lipid hydroperoxides and HDL-PON activity. Erythrocyte membranes obtained from healthy subjects were oxidized with 2,2-azo-bis(2-aminidinopropane)dihydrochloride and then incubated in the presence of HDL isolated from healthy or type 1 diabetic subjects, with measurements of membrane lipid hydroperoxides before and after the incubation. HDL from type 1 diabetic patients showed higher levels of lipid hydroperoxides and a lower activity of HDL-PON than healthy subjects. Moreover, HDL of type 1 diabetic patients protected less efficiently erythrocyte membranes against oxidative damage compared with HDL from healthy subjects. A negative correlation was found between HDL-PON activity and the levels of hydroperoxides of HDL, confirming the relationship between PON and lipid peroxidation and suggesting that subjects with low PON activity are more exposed to oxidative damage than subjects with high PON activity. The ability of HDL to protect erythrocyte membranes was positively correlated with HDL-PON activity and negatively correlated with the levels of lipid hydroperoxides of HDL of healthy subjects. These results confirm a linkage between PON activity and lipid peroxidation of lipoproteins and suggest that the ability of HDL to protect erythrocyte membranes might be related to the PON activity. It might be hypothesized that the decrease of PON activity in diabetic patients and the lower HDL protective action against membrane peroxidation could contribute to acceleration of arteriosclerosis in type 1 diabetes mellitus.

Reduced sensitivity of platelets from type 2 diabetic patients to acetylsalicylic acid (aspirin)—its relation to metabolic control

Aspirin (acetylsalicylic acid, ASA), which is recommended for primary and secondary prevention in diabetes mellitus (DM), has been shown to have a lower antiplatelet activity in diabetic patients. We conducted a crossover designed observational study to evaluate whether there is an association between the parameters relevant to metabolic control of diabetes and platelet sensitivity to aspirin in type 2 diabetic patients. Platelets' ability to adhere and aggregate was monitored with the use of platelet function analyser (PFA-100™ collagen/epinephrine closure time, CT CEPI or collagen/ADP closure time, CT CADP), classical turbidimetric aggregometry and whole blood electrical aggregometry (WBEA), using collagen (WBEA coll), ADP (WBEA ADP) and arachidonic acid (WBEA AA) as platelet agonists, in 48 control healthy volunteers (mean age±S.D., 49±9 years) and 31 type 2 DM patients (50±9 years; HbA 1c 9.4±1.6%). In majority of control subjects (69%) and minority of diabetic patients (29%, p=0.0006), the use of 150 mg aspirin daily for 1 week significantly reduced platelet adhesiveness and reactivity (by 14.1% in diabetes vs. 78.6% in control, p np=0.0035, as expressed by the relative changes in CT CEPI). Aspirin reduced WBEA coll and WBEA AA to a lesser extent in diabetic patients (by 2.1% vs. 8.3% in controls, p np=0.0397, and by 97.3±12.8% vs. 100% in controls, p np=0.0383, respectively), which corresponded to ASA-mediated decreased aggregation in platelet-rich plasma (PRP, r S=0.45 and r S=0.78 for collagen- or arachidonate-agonized platelets, p<0.01 or lower). The maximal inhibition of platelet aggregation was lower and IC 50 higher in diabetic compared to control subjects, both in the presence of arachidonic acid (71% vs. 39%, p np≪0.0001; 0.5 μg/ml vs. 1.3 μg/ml, p<0.0001) and collagen (52% vs. 35%, p<0.0004; 1.6 μg/ml vs. 2.1 μg/ml, p<0.01). The reduced response of platelets from diabetic subjects to aspirin was associated with a higher level of HbA 1c, lower concentration of HDL-cholesterol and a higher total cholesterol concentration. Overall, there is evidence that reduced platelets response to aspirin may occur more often in diabetic patients. Poor metabolic control may play a role in the reduced platelet sensitivity to aspirin in DM patients. Thus, our findings strongly support the requirements for an excellent near-normal metabolic control and may suggest a need for alternative ASA dosing schedules in DM patients.

Meal modulation of circulating interleukin 18 and adiponectin concentrations in healthy subjects and in patients with type 2 diabetes mellitus

A single high-fat meal induces endothelial activation, which is associated with increased serum concentrations of inflammatory cytokines. We compared the effect of 3 different meals on circulating concentrations of interleukin 8 (IL-8), interleukin 18 (IL-18), and adiponectin in healthy subjects and in patients with type 2 diabetes mellitus. Thirty patients with newly diagnosed type 2 diabetes and 30 matched, nondiabetic subjects received the following 3 isoenergetic (780 kcal) meals separated by 1-wk intervals: a high-fat meal; a high-carbohydrate, low-fiber (4.5 g) meal; and a high-carbohydrate, high-fiber meal in which refined-wheat flour was replaced with whole-wheat flour (16.8 g). We analyzed serum glucose and lipid variables and serum IL-8, IL-18, and adiponectin concentrations at baseline and at 2 and 4 h after ingestion of the meals. Compared with nondiabetic subjects, diabetic patients had higher fasting IL-8 (P < 0.05) and IL-18 (P < 0.01) concentrations and lower adiponectin concentrations (P < 0.01) at baseline. In both nondiabetic and diabetic subjects, IL-18 concentrations increased and adiponectin concentrations decreased (P < 0.05) from baseline concentrations after consumption of the high-fat meal. After consumption of the high-carbohydrate, high-fiber meal, serum IL-18 concentrations decreased from baseline concentrations (P < 0.05) in both nondiabetic and diabetic subjects; adiponectin concentrations decreased after the high-carbohydrate, low-fiber meal in diabetic patients. IL-8 concentrations did not change significantly after consumption of any of the 3 meals. This study provides evidence that circulating IL-18 and adiponectin concentrations are modulated by familiar foodstuffs in humans. Meal modulation of cytokines involved in atherogenesis may represent a safe strategy for ameliorating atherogenetic inflammatory activity in diabetic patients.

Paraoxonase (Pon1) Q192R polymorphism and serum Pon1 activity in diabetic patients on maintenance hemodialysis.

Patients with diabetic nephropathy have an increased risk of coronary heart disease (CHD). Paraoxonase (Pon1) is a high-density lipoprotein- (HDL) associated enzyme that protects low-density lipoprotein from oxidation and also protects against atherosclerosis. We investigated the relationship of serum Pon1 activity, Pon1 Q192R polymorphism and HDL-C level to type 2 diabetes mellitus (DM) in patients on maintenance hemodialysis (HD). DM patients (n = 56, F/M = 17/39, aged 64.5 +/- 7.5 years) and non-DM patients (n = 89, F/M = 28/61, aged 62.7 +/- 8.3 years) under HD were included in this study. Salt-stimulated serum Pon1 activities were measured using paraoxon as a substrate. Pon1 Q192R polymorphism was detected by the mutagenically separated polymerase chain reaction. DM patients on HD had significantly lower HDL-C levels and serum Pon1 activities than non-DM patients on HD (657 +/- 277 vs. 763 +/- 257 IU/l, p < 0.01). The distribution of Pon1 Q 192R genotypes in all subjects did not differ from that predicted from the Hardy-Weinberg equilibrium. Serum Pon1 activities in both DM and non-DM patients on HD were regulated by Pon1 Q192R polymorphism: RR > QR > QQ. However, the reduced Pon1 activities in DM patients on HD were related to DM independent of the Pon1 genotype: reduced Pon1 activity was related to DM in RR carriers. Serum Pon1 activities were positively correlated with HDL-C levels. The association between HDL-C and DM in hemodialyzed patients was independent of Pon1 activity as assessed by an analysis of variance. But the relation between Pon1 activity and DM was modified by HDL-C levels: significantly when HDL-C was below 50 mg/dl, but not significantly when HDL-C was above 50 mg/dl. The results of a logistic regression analysis show that reduced serum Pon1 activities and low HDL-C levels were additively associated with DM. In conclusion, Pon1 status and HDL levels are independently associated with DM in patients on hemodialysis and may contribute to the increased risk of CHD in diabetic nephropathy.

O 6-methylguanine DNA methyltransferase activity in diabetic patients

In the present study, we evaluated O 6-methylguanine-DNA methyltransferase (MGMT) activity in diabetic patients. The study was performed on 27 patients with Type 1 diabetes, and 42 with Type 2 diabetes. Patients with complications were excluded from the study. 36 non-diabetic volunteers, non-smokers who do not consume alcoholic beverage, were chosen from the medical staff as control subjects. MGMT activity was measured by the transfer of radiolabeled methyl groups from a prepared methylguanine-DNA substrate to the enzyme fraction of leukocyte extract. Leukocyte MGMT activity was significantly reduced in both Type 1 and Type 2 diabetes patients as compared with control subjects ( P<0.001). The present study demonstrates decreased MGMT activity in leukocytes from patients with Type 1 and Type 2 diabetes.

Effect of (-)epicatechin in modulating calicum-atpase activity in normal and diabetic human erythrocytes

Aqueous extract of the wood ofPterocarpus marsupium, commonly known as 'bijasar', is used in Indian Ayurveda system of medicine for treatment of diabetes. The active anti-diabetic principle in its aqueous extract has been found to be (-)epicatechin, a flavonoid. The present work was undertaken to study the effect of (-)epicatechin on erythrocyte membrane Ca(++)-ATPase from type 2 diabetic patients. The activity of erythrocyte Ca(++)-ATPase was significantly lower in type 2 diabetics.In vitro insulin treatment of erythrocyte ghosts, resulted in the increase of Ca(++)-ATPase activity in diabetic patients. Treatment with (-)epicatechin (1mM) resulted in an increase in the activity of erythrocyte Ca(++)-ATPase in both normal individuals and type 2 diabetic patients. The insulin like effect of (-)epicatechin on erythrocyte membrane Ca(++)-ATPase in type 2 diabetics is an interesting finding. Further work is needed to elucidate the mechanism of action of (-)epicatechin on modulation of erythrocyte membrane bound enzymes.

Effect of Electrical Stimulation on Acupuncture Points in Diabetic Patients with Gastric Dysrhythmia: A Pilot Study

Background/Aims: Abnormal gastric slow-wave frequencies have been observed in diabetic gastroparesis and are associated with impaired antral motor activity. In this study, we aimed at evaluating the effect of acupuncture on gastric slow waves in diabetic patients with symptoms suggesting gastric motor dysfunction. Methods: Fifteen patients with type II diabetes who had had dyspeptic symptoms for more than 3 months were enrolled. Two acupuncture needles were inserted into the subjects’ legs at the Zusanli points, and electrical stimulation (2-Hz pulses) was delivered for 30 min. Cutaneous electrogastrography was performed for 30 min at baseline, for 30 min during acupuncture, and for an additional 30 min after acupuncture. Serum gastrin, motilin, and human pancreatic polypeptide levels were also measured. Results: There was a significant increase in the percentages of normal frequency during and after acupuncture (baseline vs. acupuncture and after acupuncture 21.99 ± 19.38% vs. 45.93 ± 19.72 and 48.92 ± 19.56%; p < 0.01). In addition, the percentage of tachygastric frequency was decreased significantly during and after acupuncture. The dominant frequency was also changed significantly. There was an increase of serum human pancreatic polypeptide during acupuncture (baseline vs. acupuncture 56.96 ± 27.64 vs. 73.11 ± 22.37 pmol/l; p < 0.05). Conclusions: The results of this study revealed that electrical stimulation at the Zusanli points could increase the percentage of normal electrogastrography frequency and decrease the percentage of tachygastric frequency in diabetic patients. The data indicate that acupuncture may enhance the regularity of gastric myoelectrical activity in diabetic patients.

Partial breakdown of glycated alkaline phosphatases mediated by reactive oxygen species

The lower levels of serum alkaline phosphatase (AP) activity found in patients with diabetes mellitus apparently originate from the selective disappearance or decrease in bone AP activity in the circulation. Hence, we investigated in vitro the effect of glycation on the activities of five AP isozymes. Aseptic incubation with 25 mmol/L of d-glucose and APs rapidly reduced bone and placental AP activities before those of liver, kidney and intestinal enzymes. The resulting bone and placental AP molecules were clearly glycated, according to the result of aminophenylboronic acid affinity chromatography. Furthermore, Western blotting analysis revealed that the placental AP molecule was fragmented, and its partial cleavage took place at Ala 154 on the AP molecule. Since glycation of serum proteins causes the generation of reactive oxygen species, the effects of reactive oxygen species on placental AP activity were assayed, and the results indicated that hydroxyl radicals might be a major factor for the specific inactivation of AP activities. The reduction in AP activity by incubation with glucose in vitro was reversed by the further addition of catalase. Furthermore, ferrous ion with hydrogen peroxide, which generates hydroxyl radicals, had an inhibitory effect on AP activities. These findings suggest that the reduced AP activity in diabetic patients might result from partial cleavage of the bone AP molecule by reactive oxygen species induced by glycation.

Decreased nitric oxide synthase activity in platelets from IDDM and NIDDM patients.

Nitric oxide (NO) produced by platelet nitric oxide synthase (NOS) inhibits platelet activation by increased cytoplasmic cGMP levels. The aim of this study was to investigate platelet NOS activity in insulin-dependent (IDDM) and non-insulin-dependent diabetes mellitus (NIDDM), which are characterized by enhanced platelet activation. HbA1c levels, platelet NOS and platelet membrane Na+/K+ ATPase activity were determined in 19 IDDM patients, 21 NIDDM patients and 31 healthy control subjects. NOS activity was measured by a spectrophotometric method based on NO-dependent oxidation of oxyhaemoglobin to met-haemoglobin. Na+/K+ ATPase activity was measured by the method of Kitao and Hattori. Both NOS and Na+/K+ ATPase activity were significantly reduced in diabetic subjects compared with control subjects. NOS showed a significant negative relation with HbA1c levels and a positive relation with Na+/K+ ATPase activity in diabetic patients. It is hypothesized that the decreased NOS activity might play a role in the pathogenesis of diabetic vascular complications.

Effect of tolrestat, an aldose reductase inhibitor, on neutrophil respiratory burst activity in diabetic patients

One hypothesis for the reduction in oxidative killing of neutrophils in diabetic patients is that increased polyol pathway activity during hyperglycemia reduces intracellular levels of nicotinamide adenine dinucleotide phosphate (NADPH), resulting in the reduction of neutrophil superoxide production during the respiratory burst. To test this hypothesis, we assessed the effect of tolrestat, an aldose reductase inhibitor, on neutrophil respiratory burst activity (NRBA) in diabetic patients. We measured fasting plasma glucose (FPG), hemoglobin A 1 (HbA 1), and NRBA levels in 79 diabetic patients and 48 normal controls. NRBA was reassessed in 34 patients after 4 weeks of tolrestat or placebo treatment, in seven controls after 4 weeks of tolrestat treatment, and in seven patients after 4 weeks of blood glucose control. NRBA was determined by flow cytometry, which detected fluorescent 2′,7′-dichlorofluorescein (DCF) in neutrophils formed from 2′,7′-dichlorofluorescein diacetate (DCF-DA) during phorbol myristate acetate (PMA)-induced respiratory bursts. Diabetic patients showed lower NRBA than the normal controls (mean cellular fluorescence, 438 ± 103 v 668 ± 101, mean ± SD, P < .001). NRBA, in diabetic patients showed a negative correlation with HbA 1 ( r = −.336, P < .005). Tolrestat treatment for 4 weeks in 17 patients restored the reduced NRBA to an almost normal level (relative NRBA, 0.55 ± 0.20 v 0.99 ± 0.36, P < .05) despite the fact that FPG level did not change (11.8 ± 2.8 v 11.4 ± 2.8 mmol/L). NRBA of these patients after tolrestat treatment was not significantly different from that of seven control subjects treated with tolrestat for 4 weeks. In 17 placebo-treated patients, there were no significant changes in NRBA and FPG level. The vigorous blood glucose control for 4 weeks in seven patients (16.6 ± 2.1 v 8.6 ± 2.3 mmol/L) also restored the reduced NRBA to almost normal (relative NRBA, 0.55 ± 0.21 v 0.90 ± 0.30, P < .05). The result that the reduced NRBA in diabetic patients was restored to almost normal either by tolrestat treatment or by blood glucose control strongly supports the hypothesis of this study.

Reduced lecithin: Cholesterol acyltransferase (LCAT) and Na +,K +,ATPase activity in diabetic patients

Objectives: To investigate the plasma concentrations of lecithin:cholesterol acyltransferase (LCAT EC 2.3.1.43) and erythrocyte membrane Na +,K +,ATPase and the correlation of these parameters in diabetes mellitus. Design and Methods: Na +,K +,ATPase was measured with spectrophotometric method and LCAT with radioactive method in 19 patients with insulin-dependent diabetes mellitus (IDDM), in 20 with non-insulin-dependent diabetes mellitus (NIDDM) and in 20 healthy volunteers as the control group. Results: Compared with the control group, plasma LCAT concentrations were found to be decreased in both of the patient groups ( p < 0.01 for both). Erythrocyte membrane Na +,K +,ATPase activities were higher in the controls than both in the NIDDM and IDDM groups ( p < 0.01 and p < 0.001, respectively). There were significant correlations between LCAT and Na +,K +,ATPase in IDDM ( r = 0.82, p < 0.001) and in NIDDM ( r = 0.74, p < 0.001). In order to investigate the effect of cholesterol (C) and lysophosphatidylcholine (LPC) on Na +,K +,ATPase activity, this enzyme's activity was determined in erythrocyte membranes obtained from diabetic subjects after in vitro incubation with increasing concentrations of LPC and C (2–10 μM). Enzymatic activity was significantly reduced by in vitro C at increasing concentrations but significantly increased by in vitro LPC at increasing concentrations. Conclusions: From these data, it is to be concluded that the decrease in Na +,K +,ATPase activity in diabetes might be due to decreased LCAT concentrations and that may explain the development of atherosclerosis in diabetics.

Decreased sympatho-adrenal activity in diabetic patients with autonomic dysfunction following mental stress

Decreased sympatho-adrenal activity in diabetic patients with autonomic dysfunction following mental stress

Decreased sympatho-adrenal activity in diabetic patients with autonomic dysfunction following mental stress

The sympathetic nervous system is of major importance in the regulation of numerous physiological functions. While it is clearly established that there is a decreased noradrenergic status in people with autonomic neuropathy, the epinephrine secretion is much more controversial. Basal and mental stress-stimulated plasma catecholamine levels were measured in 42 diabetic patients with and without pathological cardiovascular function tests and in 13 healthy, non-diabetic control subjects. In addition, the excretion of catecholamines was measured in a 24 h urine collection and compared with the stress stimulated plasma levels. During mental stress exposure a diminished epinephrine secretion was found in diabetic patients with autonomic neuropathy compared with diabetic patients without neuropathy and the healthy control group ( p < 0.05; respectively). The decreased epinephrine response to mental stress was strongly correlated with a diminished urinary excretion of this ‘neurotransmitter’ ( r = 0.46; p < 0.01). Diabetic patients suffering from cardiovascular autonomic neuropathy exhibit a diminished sympatho-adrenal response following mental stress exposure. Both measurement of urinary and mental stress stimulated plasma epinephrine levels following mental stress provide reliable information regarding sympatho-adrenal activity in diabetic patients.

Reduction of Leucocyte Proteolytic Enzyme Activity in Diabetic Patients with Microalbuminuria and Proteinuria: Its Possible Role in Diabetic Nephropathy

Mesangium enlargement and glomerular basement membrane thickening are cardinal features of diabetic nephropathy. The reasons for these changes are uncertain but decreased degradation of extracellular matrix may play a role. Mesangium degradation can be modulated by factors intrinsic to the kidney or by factors in the circulation. In this study the capacity of leucocyte proteolytic enzymes to degrade mesangium matrix materials was investigated. Leucocytes were obtained from 57 patients with NIDDM (age 58.3 +/- 8.8 years, duration 9.4 +/- 7.3 years, body mass index (BMI) 30 +/- 6 kg m-2, HbA1c 7.7 +/- 2.0%) and 21 control subjects (age 55.1 +/- 14.6 years, BMI 25 +/- 4 kg m-2). Leucocyte lysates from control and NIDDM subjects with normal AER degraded matrix to the same extent (40.6 +/- 8.2% vs 42.9 +/- 13.5%) while lysates from patients with microalbuminuria and proteinuria were less able to degrade matrix (33.0 +/- 14.2% and 26.1 +/- 12.7%, respectively). There was a significant inverse correlation between matrix degradation and AER (r = -0.49) and multiple regression analysis showed that AER was the most important factor determining degradation rate (R2 = 0.24). Degree of metabolic control, age, and blood pressure were not significant factors. The major enzyme(s) responsible for the matrix degradation was identified as metalloproteinase(s). We conclude that leucocytes from diabetic patients with abnormal albumin excretion have a decreased proteolytic capacity to degrade extracellular matrix. This may play a role in the glomerular basement membrane thickening and mesangium expansion which occurs in diabetic nephropathy.

Anti‐Gal activity In diabetic patients transplanted with fetal porcine Islet cell clusters

The natural anti-Gal antibody seems to create a major obstacle for discordant xenotransplantation in humans. Anti-Gal, which is produced in large amounts in humans (1% of circulating IgG), interacts specifically with the carbohydrate structure Gal alpha 1-3Gal beta 1-4Glc-NAc-R (termed the alpha-galactosyl epitope). This epitope is present in large amounts on porcine cells, as well as on cells of other nonprimate mammals (1 x 10(6) to 35 x 10(6) epitopes/cell). The interaction of anti-Gal with alpha-galactosyl epitopes on the xenograft was found to mediate the immune destruction of discordant xenografts. In the present study, the human immune response to alpha-galactosyl epitopes on xenografts was assessed by measuring changes in anti-Gal titers and affinity in sera of diabetic patients transplanted with fetal porcine islet cell clusters. The activity of this antibody was assessed by a hemagglutination assay with RBC, by ELISA with mouse laminin as a solid-phase antigen, and by equilibrium dialysis with the radiolabeled free haptenic form of the alpha-galactosyl epitope, i.e. [3H]Gal alpha 1-3Gal beta 1-4GlcNAc. All assays revealed a marked increase in anti-Gal activity after transplantation. The increase in anti-Gal titers ranged between 8- and 64-fold. A similar increase was observed in the binding of free alpha-galactosyl epitopes to anti-Gal, as assayed in equilibrium dialysis. Immunoglobulin concentration did not increase after transplantation, suggesting that the observed increase in anti-Gal activity is the result of a specific immune response against alpha-galactosyl epitopes on the xenograft. The elevation in anti-Gal activity was observed in all three immunoglobulin classes and the highest activity was found within the IgG class. Analysis of IgG binding to fixed porcine endothelial cells suggested that most of the observed increased activity against these cells in transplanted patients may be attributed to the elevation in anti-Gal activity.

Metabolic control quality and free radical activity in diabetic patients

The role of oxidative/reductive balance derangement in the pathogenesis of diabetic microangiopathy has often been discussed in the last few years. Therefore, we decided to evaluate the influence of intensive insulin therapy on selected indicators of free radical production. The levels of plasma hydrogen peroxide (H 2O 2) and serum malonyldialdehyde (MDA) were estimated in 15 patients with Type 1 and 15 with Type 2 diabetes before and after 2 weeks of intensive treatment. The initial H 2O 2 and MDA levels in all cases were significantly higher than in controls. After 2 weeks of treatment, the values for both estimated parameters were significantly lower; however, they were still higher than in the control group. Our results seem to confirm the previous suggestions concerning the relation between metabolic disturbances and oxidative stress in diabetic patients.

Increased serum angiotensin converting enzyme activity in type I insulin-dependent diabetes mellitus: its relation to metabolic control and diabetic complications.

Serum angiotensin-converting enzyme (ACE) was measured in 150 insulin-dependent diabetes mellitus (IDDM) patients and 72 healthy subjects by radioassay, using [3H]-hippuryl-glycyl-glycine as a substrate. Mean (SD) serum ACE activity in diabetic patients was 120 +/- 33 nmol ml-1 min-1 (range 46-215) and was significantly increased by 56% compared to control values (77 +/- 23 nmol ml-1 min-1, range 46-125, P < 0.001). ACE activity > 125 nmol ml-1 min-1 was observed in 60 of 150 IDDM patients. 96 IDDM patients were normoalbuminuric (< 22 mg 24 h-1) and 49 patients were micro- or macroalbuminuric (range 22-6010 mg 24 h-1). Micro- and macroalbuminuric IDDM patients were found to have significantly greater ACE activity values than normoalbuminuric patients (128 +/- 36 vs. 115 +/- 30 nmol ml-1 min-1, P = 0.025). Metabolically well-controlled IDDM patients (glycosylated haemoglobin < or = 8%) had lower ACE activity values than the patients with glycosylated haemoglobin greater than 8% (109 +/- 20 vs. 127 +/- 32 nmol ml-1 min-1, P < 0.02). A significant correlation between degree of metabolic control and ACE activity was found (r = 0.435, P < 0.001) so that an increase in one glycosylated quartile unit is accompanied by an increase in ACE activity of 10.5 nmol ml-1 min-1. Thus ACE activity in the serum of IDDM patients was increased by 56% in 40% of the patients. It was increased in IDDM patients without complications and in patients with retinopathy or nephropathy.(ABSTRACT TRUNCATED AT 250 WORDS)

Reduction of erythrocyte (Na(+)-K+)ATPase activity in type 2 (non-insulin-dependent) diabetic patients with microalbuminuria.

In order to elucidate the causal relationship between (Na(+)-K+)ATPase and diabetic nephropathy, we studied the erythrocyte (Na(+)-K+)ATPase activity in Type 2 diabetic patients, 20 with microalbuminuria and 27 without microalbuminuria and in 16 control subjects. (Na(+)-K+)ATPase activities in microalbuminuric patients (0.273 +/- 0.012 mumol Pi/mg protein/h, mean +/- SE) were significantly reduced compared with those without microalbuminuric patients (0.308 +/- 0.011 mumol Pi/mg protein/h, p < 0.05) and control subjects (0.330 +/- 0.011 mumol Pi/mg protein/h, p < 0.01). Microalbuminuric patients had higher systolic blood pressure (133 +/- 3 vs 124 +/- 3 mmHg, p < 0.05) and greater frequency of parental hypertension (50% vs 19%, p < 0.05) than those without microalbuminuria. (Na(+)-K+)ATPase activities in diabetic patients with hypertension were significantly reduced compared with those in diabetic patients without hypertension. Moreover, (Na(+)-K+)ATPase activities in diabetic patients with parental hypertension were significantly reduced compared with those in patients without parental hypertension. There was no difference in erythrocyte Na+ content between with and without microalbuminuria or hypertension or parental hypertension in diabetic patients. Erythrocyte Na+ content was significantly negatively correlated with (Na(+)-K+)ATPase activity in control subjects (r = -0.619, p < 0.05), but not in diabetic patients (r = -0.194). Plasma digitalis-like substances showed no correlation with (Na(+)-K+)ATPase activities in diabetic patients with microalbuminuria or hypertension or parental hypertension. We concluded that the reduction of erythrocyte (Na(+)-K+)ATPase activity may be related to a familial predisposition to arterial hypertension and may partly be responsible for the development of diabetic nephropathy in Type 2 diabetic patients.