Abnormal membrane fluidity and acetylcholinesterase activity in erythrocytes from insulin-dependent diabetic patients

An alteration in the enzymatic properties of the erythrocyte membrane acetylcholinesterase (AchE) and Na+,K+-ATPase has been described in experimental diabetes mellitus. We studied erythrocyte membrane fluidity and AchE and Na+,K+-ATPase activities in 15 insulin-dependent diabetic patients and 11 normal subjects. Fluidity was assessed by fluorescence polarization, using 1,6-diphenyl-1,3,5-hexatriene as a probe, and AchE and Na+,K+-ATPase activities were measured enzymatically. We found a significant increase in the enzymatic activity of AchE and a change in its enzymatic properties in diabetic patients compared with those in normal subjects. AchE activity correlated inversely with membrane fluorescence polarization, which was decreased in the diabetic patients, indicating an increase in membrane fluidity. Na+,K+-ATPase activity was reduced in the diabetic patients and correlated positively with the fluorescence polarization values. We hypothesize that the abnormal dynamic properties of the erythrocyte membrane may play a major role in determining the described change in enzymatic activity.     

The incidence of gastric and thyroid autoimmunity in insulin-dependent greek diabetic patients

The prevalence of antibodies against parietal cell cytoplasm, intrinsic factor, and thyroid cell cytoplasm was studied in 500 insulin-dependent Greek diabetics and 300 normal control subjects. All three antibodies were found to be significantly increased in the diabetic group. The incidence of antibodies increased with age and was higher in female diabetics. Greek diabetic patients have an incidence of intrinsic factor antibody similar to that found in other European diabetics but higher than that reported in Indian diabetics.     

Plasma lipid fatty acids and platelet function in insulin-dependent diabetic patients

Platelet function, estimated from plasma beta-thromboglobulin (beta-TG, ng/ml), is frequently altered in insulin-dependent diabetics (IDDs). As several factors may affect beta-TG, we studied respectively in 15 IDDs, the roles played by: (i) diabetic control evaluated from glycosylated haemoglobin (HbA1); (ii) plasma C-peptide and pancreatic glucagon; (iii) plasma lipids and the relative percentages of fatty acids in total plasma lipids. Plasma beta-TG did not correlate significantly with the first 3 parameters. However, beta-TG was correlated: (i) positively with plasma triglycerides (P less than 0.01), cholesterol (P less than 0.02), phospholipids (P less than 0.05) and total plasma lipids (P less than 0.01) and the percentage of oleic acid (C18 : 1 omega 9) in plasma lipids (P less than 0.01); (ii) negatively with the percentage of linoleic acid (C18 : 2 omega 6) in plasma lipids (P less than 0.02). No correlation was found between beta-TG and the percentages of the other saturated (C16 : 0, C18 : 0), monounsaturated (C16 : 1 omega 7) and polyunsaturated fatty acids (C18 : 3 omega 6, C20 : 3 omega 6 and C20 : 4 omega 6). The present results indicate that beta-TG in IDDs can be markedly improved by all dietary and therapeutic measures which lower plasma lipids and increase the percentage of the linoleic acid in the body.     

Pulmonary function in young insulin-dependent diabetic subjects

To clarify the issue of pulmonary dysfunction in diabetes mellitus, lung mechanics and CO transfer were investigated in 22 young (mean age 19.5 +/- 5 years) non-smoking, insulin-dependent diabetic patients and an equal number of matched healthy subjects. Mean closing capacity/total lung capacity (CC/TLC) was significantly greater in the diabetic than in the control group (31.4 +/- 6.8 vs 27.2 +/- 2.9 percent, p less than 0.01), as was the mean value of the volume independent index of lung elasticity (exponent constant, Kst(L)) (0.148 +/- 0.045 vs 0.118 +/- 0.030, p less than 0.05). The transfer factor expressed per unit alveolar volume (TL/VA) was also significantly lower in the diabetic than in the control group (5.25 +/- 0.68 vs 5.61 +/- 0.57 ml/min/mm Hg/L, p less than 0.05) and this could be ascribed to a lower pulmonary capillary blood volume. There was evidence of mildly abnormal lung mechanics and/or a decreased pulmonary capillary blood volume in 16 (73 percent) of the diabetic group. Since pulmonary dysfunction was either an isolated non-endocrine finding or was associated with only early systemic complications in these young patients, our findings suggest that pulmonary dysfunction is an early measurable complication in insulin-dependent diabetes mellitus.     

Platelet function in uncomplicated insulin-dependent diabetic patients at rest and following exercise

There are conflicting reports of platelet function abnormalities in diabetic patients without vascular complications. We have studied in vitro platelet aggregation, using platelet rich plasma and whole blood techniques, in 18 patients with uncomplicated insulin-dependent diabetes and a matched group of 24 non-diabetic subjects. In addition we measured plasma beta-thromboglobulin levels in these groups, as an index of in vivo platelet activation, and compared the indices of in vitro and in vivo platelet function before and after maximal bicycle exercise. Before exercise plasma beta-thromboglobulin levels and platelet sensitivities to ADP, collagen or adrenaline, as assessed by both methods of platelet aggregation, were the same in diabetic and control subjects. Both groups showed similar increases in beta-thromboglobulin levels and in platelet sensitivity to all agonists in whole blood following exercise. Using platelet rich plasma there were no changes in platelet sensitivity in either group after exercise. In non-diabetic subjects, increases in noradrenaline levels after exercise correlated with increases in platelet sensitivity to adrenaline in whole blood. This was not observed in the diabetic group. Abnormalities of platelet function, using the techniques described here, are not present in diabetic patients who do not have clinical evidence of vascular disease.     

Abnormal foot function in diabetic patients: the altered onset of Windlass mechanism.

AIM: The aim of this study was to examine foot function in the presence of diabetes-induced alterations of the anatomical and biomechanical unit formed by the Achilles tendon, plantar fascia and metatarso-phalangeal joints. More specifically, we focused on the Windlass mechanism, the physiological mechanism which entails stiffening of the foot during propulsion. METHODS: Sixty-one diabetic patients, with or without neuropathy, and 21 healthy volunteers were recruited. The thickness of Achilles tendon and plantar fascia was measured by ultrasound. The main biomechanical parameters of foot-floor interaction during gait were acquired by means of dedicated platforms. The range of motion of the 1st metatarso-phalangeal joint was measured passively. RESULTS: The plantar fascia (PF) and Achilles tendon (AT) were significantly thickened in diabetic patients [control subjects: PF 2.0+/-0.5 mm, AT 4.0+/-0.5 mm; diabetic patients without neuropathy: PF 2.9+/-1.2 mm (P=0.002), AT 4.6+/-1.0 mm (P=0.016); diabetic patients with neuropathy: PF 3.0+/-0.8 mm (P<0.0001), AT 4.9+/-1.7 mm (P=0.026)]. Joint mobility was significantly reduced [control subjects: 100.0+/-10.0 degrees; diabetic patients without neuropathy: 54.0+/-29.4 degrees (P<0.0001); diabetic patients with neuropathy: 54.9+/-17.2 degrees (P<0.0001)]. Loading times and force integrals under the heel and the metatarsals increased [metatarsal loading time (% stance phase): control subjects 88.2+/-4.1%; diabetic patients without neuropathy 90.1+/-4.7% (P=0.146); diabetic patients with neuropathy 91.7+/-6.6% (P=0.048)]. CONCLUSIONS: Increased thickness of Achilles tendon and plantar fascia, more evident in the presence of neuropathy, may contribute to an overall increase of tensile force and to the occurrence of an early Windlass mechanism, maintained throughout the whole gait cycle. This might play a significant role in the overall alteration of the biomechanics of the foot-ankle complex.     

Normoalbuminuria ensures no reduction of renal function in type 1 (insulin-dependent) diabetic patients.

Recent reports have suggested that impaired renal function in type 1 diabetic patients may be present despite normal urinary albumin excretion (UAE). We have studied kidney function by means of a constant-infusion technique in normoalbuminuric type 1 diabetic patients without antihypertensive medication (UAE less than 20 micrograms min-1, n = 134), in microalbuminuric patients (20 greater than or equal to UAE less than 200 micrograms min-1, n = 50) and in 27 non-diabetic control subjects. Mean UAE was 4.5 micrograms min-1 (range 1.0-19.3 micrograms min-1) in normoalbuminuric patients, 53.1 micrograms min-1 (range 20.8-147.5 micrograms min-1) in microalbuminuric patients, and 4.0 micrograms min-1 (range 2.1-17.9 micrograms min-1) in controls. Glycosylated haemoglobin A1c was significantly higher in microalbuminuric patients (8.9%, range 5.9-12.6%) than in normoalbuminuric patients (7.9%, range 5.5-11.5%) (P less than 0.0001). Glomerular filtration rate in normoalbuminuric patients (135 ml min-1, range 97-198 ml min-1) was significantly higher than in controls (118 ml min-1, range 94-139 ml min-1) (P less than 1 x 10(-6), and significantly lower than in microalbuminuric patients (142 ml min-1, range 100-186 ml min-1) (P less than 0.05). Mean arterial blood pressure was lower in normoalbuminuric patients (91 mmHg, range 78-108 mmHg) than in microalbuminuric patients (98 mmHg, range 82-131 mmHg) (P less than 1 x 10(-6), but not significantly different from that of controls (89 mmHg, range 73-103 mmHg). We conclude that normal UAE is a reliable indicator of well-preserved renal function. Glomerular hyperfiltration, elevated blood pressure and poor metabolic control are characteristic features of microalbuminuric patients.     

Cognitive function in Type 1 (insulin-dependent) diabetic patients after nocturnal hypoglycaemia

Summary Eight Type 1 (insulin-dependent) diabetic patients with no diabetic complications were studied on two consecutive and one subsequent overnight occasions. The aim was to evaluate the influence of nocturnal hypoglycaemia on neuropsychological and reaction time tests the following morning. Hypoglycaemia was induced by i. v. insulin infusion, blood glucose nadir was 1.5±0.3 mmol/l. Duration of hypoglycaemia (blood glucose < 3 mmol/l) was 101±38 min. Whole night sleep statistics for all patients showed no statistical differences between the normoglycaemic and hypoglycaemic nights, however, there was a tendency of prolongation of the second sleep cycle in the nights with hypoglycaemia. Each patient was used as his own control and periods with blood glucose concentration less than 3 mmol/l were compared to exactly the same periods in nights with blood glucose level over 5 mmol/l. During hypoglycaemia the amount of deep sleep was reduced and replaced by superficial sleep and arousals of short duration. Further, the reduction in deep sleep was replaced later at night. Neuropsychological test scores and reaction time measurements in the morning showed no differences between the normoglycaemic and hypoglycaemic nights. In conclusion: despite sleep disturbances, nocturnal hypoglycaemia did not impair cognitive function the following morning in Type 1 (insulin-dependent) diabetic patients.     

糖尿病病人胃排空功能的研究

用Ｂ超观察了２２例糖尿病病人折胃排空功能变化。１３例有胃排空延缓，占全组５９．９９％，主要表现为胃全排空时间的延长。胃排空延缓与病程及慢性病变相关，且糖尿病胃排空延缓组较排空非延缓组餐后血糖值明显增高，故糖尿病胃排空延缓既可能是糖尿病的又一慢性病变，也可能受到高血糖本身的调控。     

Effects of acetazolamide on kidney function in Type 1 (insulin-dependent) diabetic patients with diabetic nephropathy

Summary We investigated the effects of 3 days treatment with acetazolamide 250 mg three times daily on kidney function in 8 Type 1 (insulin-dependent) diabetic patients with nephropathy, and in 7 healthy subjects in a double-blind placebo controlled cross-over study. Glomerular filtration rate and extracellular fluid volume were measured with the single injection ⁵¹Cr-EDTA technique and fluid flow rate from the proximal tubules was determined by measurement of the renal lithium clearance. A 24% decline in glomerular filtration rate was observed in both groups during acetazolamide treatment (control subjects: 108±11 vs 82±9 ml/min, p<0.02, diabetic patients: 71±19 vs 54±14 ml/min, p<0.01). The renal lithium clearance (ml/min) remained about the same (control subjects: 22±6 vs 27±8, NS, diabetic patients: 14±5 vs 15±4, NS). Absolute proximal tubular reabsorption of water (ml/min) was reduced by about one-third (control subjects: 85±11 vs 56±7, p<0.02, diabetic patients: 55±17 vs 37±6, p<0.02), and fractional proximal reabsorption of water and sodium (%) declined (control subjects: 79±5 vs 67±8, p<0.02, diabetic patients: 79±5 vs 72±6, p<0.02). Renal sodium clearance and distal fractional reabsorption of sodium was unchanged. Extracellular fluid volume declined by 10% in both groups (p<0.02). Albuminuria and fractional albumin clearance decreased significantly in the nephropathic patients (p<0.02). Our study suggests that the effects of acetazolamide on kidney function are similar in healthy subjects and patients with diabetic nephropathy.     

Increased forearm blood flow in longstanding Type 1 diabetic patients without microvascular complications.

AIMS: According to the 'haemodynamic hypothesis', chronic hyperglycaemia induces an increase in tissue perfusion that predisposes to microangiopathy. We hypothesized that patients with longstanding diabetes mellitus (DM), who have not developed microvascular complications, would have normal tissue perfusion. METHODS: In six Type 1 diabetic patients (age 43.4 +/- 1.1 years; DM duration 25.3 +/- 2.6 years.; HbA(1c) 8.5 +/- 0.7%), who had no evidence of microvascular complications, and six age- and gender-matched healthy volunteers (Control) we measured haemodynamic parameters including forearm blood flow (FBF; plethysmography) and sympathetic tone, an important regulator of blood flow, by the combination of plasma sampling (catecholamine levels), microneurography and power spectral analysis of blood pressure and heart rate. RESULTS: FBF was increased in the diabetic compared with control subjects (4.8 +/- 1.2 vs. 2.2 +/- 0.3 ml/dl per min, P < 0.05) and forearm vascular resistance (FVR) was decreased (25 +/- 6 and 43 +/- 3 arbitrary units, P < 0.05). Heart rate was higher in diabetic subjects (77 +/- 10 vs. 57 +/- 2 beats/min, P < 0.05). All parameters of sympathetic tone were similar in diabetic and control subjects. CONCLUSIONS: In patients with Type 1 diabetes, without signs of microvascular complications and with diabetes duration of > 20 years, skeletal muscle blood flow was increased while sympathetic tone was normal. These results suggest that increased blood flow does not inevitably lead to microvascular complications and challenge the hypothesis that it has a causative role in the pathophysiology of complications.     

Metformin improved insulin resistance in type I, insulin-dependent, diabetic patients

The biguanides have been shown to reduce insulin requirements in type I (insulin-dependent) diabetic patients with an increase in insulin binding to insulin receptors. The aim of this was to measure the effect of metformin (850 mg/twice daily) on insulin sensitivity. Ten type I diabetic patients of normal weight received metformin or placebo in addition to their insulin therapy for seven days. On the last day of metformin or placebo treatment, tissue sensitivity was measured by the euglycemic hyperinsulinaemic clamp procedure using the artificial pancreas. An 18% improvement in glucose uptake was observed after metformin therapy (P less than 0.01). Metformin was therefore effective in improving the insulin action in type I diabetic patients, although its use in such circumstances requires consideration of several other factors.     

Abnormal gastric motor function in viral gastroenteritis

Nausea and vomiting occur commonly with gastroenteritis caused by parvovirus-like agents. Infection results in histologic injury to the small bowel mucosa, but the gastric mucosa remains unaffected. We have studied gastric emptying of liquids serially in 10 volunteers before and after ingestion of the parvovirus-like agents, Norwalk and Hawaii viruses. The five subjects who developed illness all showed marked delays in gastric emptying, while the five well subjects had no alteration of emptying. Five addition volunteers who developed Norwalk virus gastroenteritis underwent serial studies of gastric secretion of hydrochloric acid, pepsin, and intrinsic factor. No change was detected in either basal or betazole-stimulated secretion of these three substances during the course of illness. The nausea and vomiting accompanying this type of viral gastroenteritis may result from abnormal gastric motor function.     

Age and metabolic control influence lens opacity in type I, insulin-dependent diabetic patients.

Cataract is a frequent ocular complication in diabetic patients, but few data are available concerning early modifications occurring in the lens of these patients and their relationship with metabolic control and other clinical parameters. We measured lens opacity in 73 type I, insulin-dependent diabetic patients aging 50 years or less and without clinical evidence of cataract, and in 46 healthy volunteers of similar age. We used a quick, simple, and reliable instrument, the Lensmeter 701, which is based on a back-light scattering quantification system and is able to quantify lens transparency along the nuclear axis. Mean lens opacity was significantly (p = 0.0001) higher in diabetic patients than in the control group, and multiple regression analysis showed that it correlated with age (p = 0.0001) and HbA1c levels (p = 0.009). Moreover in the younger group of patients (age < or =20 years) the only observed correlation was that with Hba1c (p = 0.03), whereas in the older ones (age 21-30 and >30 years) lens opacity correlated with age (p = 0.02 and p = 0.01). These data indicate that early opacifications of the lens occur in type I, insulin-dependent diabetic patients and are influenced by the degree of the metabolic control in the younger ones, whereas the well-known role of aging on lens transparency became prevalent in the older patients. Only longitudinal studies, however, can demonstrate whether these alterations represent any early stage of cataractagenesis and the role of good metabolic control in preventing this ocular complication.     

Relevance of measuring red blood cell disaggregability in insulin-dependent diabetic patients.

A viscometric study of blood from insulin-treated diabetic patients is carried out. Patients are divided into three major groups--group I: without or with minimal retinopathy and recent diabetes (n = 37), group II: without or with minimal retinopathy and at least 20 years of diabetes duration (n = 35), group III: with severe retinopathy (n = 27). Each group is also subdivided according to the glycosylated hemoglobin (HbA1c) level, used to assess long-term glycemic control. Finally, the rheological parameters of six groups are compared: three of which have a HbA1c level less than 7.5% [I1 (n = 15), II1 (n = 9), III1 (n = 9)] and three others have a HbA1c level more than 7.5% [I2 (n = 22), II2 (n = 26), III2 (n = 18)]. The most important result concerns the thixotropy index xi t, which reflects the dynamic property of red blood cell (RBC) disaggregability under shear. Strong correlations between this parameter and HbA1c level are found for groups I (r = -0.53, p < 0.001) and III (r = -0.68, p < 0.001), providing evidence of a RBC disaggregability disorder for a poor glycemic control of diabetes. In contrast, such a correlation is not pointed out for the group II. As the value for xi t is not statistically different for groups II1 and II2 and is close to the normal value in both groups, the existence of a rheological protection against the retinopathy could be involved.(ABSTRACT TRUNCATED AT 250 WORDS)     

Abnormal autonomic function in diabetic and nondiabetic patients after first acute myocardial infarction

We performed autonomic function testing in 68 patients, 34 with diabetes mellitus (group A) and 34 without (group B), at 72 h after a first acute myocardial infarction (MI) to determine the prevalence of autonomic dysfunction in these patients. Heart rate (HR) variation during 6 breaths/min obtained from mean of longest RR interval during expiration(E)/mean of shortest RR interval during inspiration (I) (E:I ratio), immediate HR response to standing = RR at 30th beat/RR at 15th beat (30:15 ratio) and postural fall of blood pressure were evaluated. In group A, 25 (78 percent) of 32 patients had an abnormal expiration-inspiration ratio compared with 28 (85 percent) of 33 in group B. Twenty-six (76 percent) patients in group A and 16 (47 percent) in group B had an abnormal 30:15 ratio. Abnormal postural fall of blood pressure was seen in 16 (47 percent) patients in group A compared with ten (29 percent) in group B. During follow-up, four women in group A with an initial autonomic dysfunction died, and in group B, three patients with a normal autonomic function died. Thus, autonomic dysfunction does not seem to contribute to the high mortality among diabetics after an acute MI.     

Dermatoglyphics in insulin-dependent diabetic patients with limited joint mobility

Hand and palm dermatoglyphics were studied in 158 insulin-dependent diabetic children and adolescents [85 with limited joint mobility (LJM) and 73 without]. The findings in this group were compared with those in 400 control subjects, with a similar racial distribution. The main dermatoglyphics alterations found in diabetic patients with LJM, as compared with non-LJM diabetic patients and controls, may be summarized as follows: (a) decrease in digital total ridges count (TRC); (b) higher frequency in the number of arches; (c) decrease in the sum of a line and cubital loops, particularly in the women; (d) increase in the number of t-axial triradii. These alterations suggest a genetic aetiology of this complication. Further studies are recommended in order to provide more insight into the origin of this disorder.     

Relationships between inflammation,hemodynamic function and RAAS in longstanding type 1 diabetes and diabetic kidney disease

The renin angiotensin aldosterone system (RAAS) is associated with renal disease and inflammation in a diabetes setting, however, little is known about the implicated mechanisms in individuals with long standing diabetes. Accordingly, our aim was to perform an observational study to quantify urinary excretion of inflammatory biomarkers in participants with long standing type 1 diabetes (T1D) (with and without diabetic kidney disease [DKD]) and controls, at baseline and in response to RAAS activation. GFR_INULIN, ERPF_PAH, and 42 urine inflammatory biomarkers were measured in 74 participants with T1D for ≥50 years (21 with DKD and 44 without DKD [DKD resistors]) and 73 healthy controls. Additionally, inflammatory biomarkers were measured before and after an angiotensin II infusion (ANGII, 1 ng?kg^?1?min^?1). Significantly lower urinary excretion of cytokines (IL-18, IL-1RA, IL-8), chemokines (MCP1, RANTES) and growth factors (TGF-α, PDGFAA, PDGFBB, VEGF-A) was observed in participants with T1D at baseline compared to controls. Urinary IL-6 was higher in DKD than in DKD resistors in an exploratory analysis unadjusted for multiple comparisons. In T1D only, lower GFR_INULIN correlated with greater excretion of proinflammatory biomarkers (IL-18, IP-10, & RANTES), growth factors (PDGF-AA & VEGFAA), and chemokines (eotaxin & MCP-1). ANGII increased 31 of 42 inflammatory biomarkers in T1D vs controls (p < 0.05), regardless of DKD resistor status. In conclusion, lower GFR and intra-renal RAAS activation were associated with increased inflammation even after longstanding T1D. The increased urinary IL-6 in patients with DKD requires further investigation to determine whether IL-6 is a candidate protective biomarker for prognostication or targeted therapy in DKD.