Mechanisms of neurodegeration in type 2 diabetes and the neuroprotective potential of dipeptidyl peptidase 4 inhibitors.

Prospective epidemiological studies suggest that type 2 diabetes is a risk factor for neurodegenerative pathologies such as Alzheimer disease, vascular dementia, and Parkinson disease. Drugs that act as incretin receptor agonists or inhibit the proteolytic degradation of incretins (dipeptidyl peptidase 4 inhibitors) have been approved since 2005 for use in diabetes treatment. Dipeptidyl peptidase 4 (DPP4) cleaves N-terminal dipeptides from polypeptides when the second residue is proline, hydroxyproline, dehydroproline or alanine. The inhibition of DPP4 hydrolytic activities extends the halflife of these peptides by preventing their degradation. Several peptides have been identified as DPP4 substrates, including neuropeptides, chemokines, and the incretin hormones; hence the pleomorphic effects of DPP4 inhibition. Recently, the neuroprotective properties of these drugs have been evaluated in cell cultures and animal models, not yet in human trials. Although mechanisms distinct from glycaemic control alone have been claimed to account for protection against neuronal degeneration, the precise cellular mechanism by which DPP4 inhibitors exert their neuroprotective effects remain unknown. The present review is focused on the candidate pathways that could be involved in mediating DPP4 inhibitors-mediated protection against neuronal degeneration.

Dietary strategies for adult type 1 diabetes in light of outcome evidence.

Individuals who have type 1 diabetes need individualised medical nutrition therapies whose goals are to improve overall health and metabolic outcomes. However, interventions in the field of nutrition are challenging, as diet-related correlations with disease remain difficult to detect and the certainty of outcome in this area is elusive. Currently, patients are not meeting recommended dietary guidelines. Several alternative approaches for teaching meal planning to people with diabetes have been proposed: basic nutrition guidelines, basic diabetes guidelines, menu approaches to meal planning, exchange lists for meal planning and carbohydrate counting. The review provides an overview of suggested strategies for achieving the proposed goals and summarises evidence of outcomes.

Epidemiology of cardiovascular disease in patients with type 1 diabetes: European perspective.

The International Diabetes Federation estimated that 5.1 million people aged between 20 and 79 years died from diabetes in 2013, accounting for 8.4% of global all-cause mortality among people in this age group. Type 1 diabetes is associated with a 2- to 4-fold increased mortality risk compared with the general population. Before the onset of late complications, most of the excess mortality is from potentially preventable causes of death such as ketoacidosis, whereas the long-term excess mortality is largely due to cardiovascular disease. However, a wide geographic variation in mortality of type 1 diabetic patients has been evidenced and accurate estimates of mortality attributable to diabetes are difficult to obtain. The review provides an overview of currently available evidence and summarizes main problems in estimating early and long-term mortality by cause of death in type 1 diabetes, paying particular attention to European studies.

Statin intolerance: why and what to do - with a focus on diabetic people.

The standards of medical care in diabetes recommend that statin therapy is added to lifestyle therapy for diabetic patients with overt cardiovascular disease (LDL cholesterol goal <70 mg/dl), or without cardiovascular disease who are over the age of 40 years and who have one or more other cardiovascular disease risk factors (LDL cholesterol goal <100 mg/dl). In order to reach strict LDL targets, high doses of statins may be required. However, the frequency of statin associated adverse effects and statin intolerance in clinical practice is high (up to 10-15% of statin users) especially at muscle level. The review overviews: 1) the known or hypothesised mechanisms through which causal and contributing factors are associated with adverse effects in diabetic people, and 2) the rationale of strategies for managing statin intolerant patients.

Dipeptidyl peptidase-4 inhibition: linking chemical properties to clinical safety.

The new drug class of dipeptidyl peptidase-4 (DPP4) inhibitors has been widely accepted in the daily management of type 2 diabetes since its strategic advantages with regard to body weight, risk of hypoglycaemia, and beta cell survival. We have previously evaluated the theoretical implications of DPP4 inhibition given that the enzyme is involved in regulating biological activity of hormones, neuropeptides, and cytokines. We intend now 1) to provide a critical appraisal of safety and tolerability as they emerged from the available clinical studies, and 2) to establish, if possible, a relation between chemical properties, biological activity, and the observed side effects in vivo.

Point-of-care testing in diabetes care.

Assessing modifiable risk factors for metabolic and cardiovascular diseases prior to the onset of disease could allow effective prevention initiatives. Equally, monitoring in diabetic people glucose, haemoglobin A1c, ketones, lipid profiles, and urinary microalbumin concentrations allows the prevention, early detection, and treatment of diabetes-related acute and chronic complications and has a positive impact on the process of care in the management of patients with diabetes. The point-of-care testing (PoCT) technology offers convenient aspects: immediate results, decision-making without the need for repeated visits, use of fingerstick blood samples. More patients could be identified at early stages of their disease/complication provided that pre-analytical, analytical, and post-analytical errors are minimised. Indeed, prediction requires instruments with proved precision, accuracy, validity, and reliability. Reference laboratory services are now available to manufacturers so to confirm PoCT results. There are several PoC devices on the market that may allow for "real time" screening, diagnosis, and monitoring in diabetes care. Tight glucose control has a key role in long-term health of diabetic people and in the primary prevention of diabetic chronic complications. Diabetic patients are currently educated to control capillary glucose levels daily in order to maintain them within target limits. Blood glucose meters are widely used not only by diabetic patients to self-manage their disease but also by physicians to monitor critically ill patients. Glycated haemoglobin A1c can now be measured with fast and easy automated PoCT instruments to monitor long-term serum glucose regulation. Urinalysis dipsticks and blood betahydroxybutyrate meter allow measuring urine and blood ketones to prevent ketoacidosis. Since the routine measurement of urinary albumin has been suggested in diabetes mellitus as a predictor of overt diabetic nephropathy, semi-quantitative visual dipsticks and quantitative automated methods of urine testing became available for bedside detection of urine albumin at low concentrations and for the determination of the microalbumin creatinine ratio. While the National Cholesterol Education Program recommends that all adults aged 20 years and over have their blood cholesterol checked at least once every 5 years, adult diabetic patients should measure fasting lipid profile at least annually or every two years in case of low-risk lipid values. There are PoCT devices on the market that provide a full lipid panel (total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglycerides). The overview summarises current state-of-the-art of PoCT in diabetes care.

Dipeptidyl peptidase-4 (CD26): knowing the function before inhibiting the enzyme.

Dipeptidyl peptidase-4 (DPP4) or adenosine deaminase complexing protein 2 (ADCP 2) or T-cell activation antigen CD26 (EC 3.4.14.5.) is a serine exopeptidase belonging to the S9B protein family that cleaves X-proline dipeptides from the N-terminus of polypeptides, such as chemokines, neuropeptides, and peptide hormones. The enzyme is a type II transmembrane glycoprotein, expressed on the surface of many cell types, whose physiological functions are largely unknown. Protein dimerisation should be required for catalytic activity and glycosylation of the enzyme could impact on its physiological functions. The dimeric glycoprotein ADCP has been found linked to adenosine deaminase (ADA) whose relationship with lymphocyte maturation-differentiation is well-established. Since implicated in the regulation of the biological activity of hormones and chemokines, such as glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide, DPP4 inhibition offers a new potential therapeutic approach for type 2 diabetes mellitus, as monotherapy and adjunct therapy to other oral agents. The clinical use of presently available orally active inhibitors of DPP4, however, has been associated with side effects that have been in part attributed to the inhibition of related serine proteases, such as DPP8 and DPP9. Indeed, it is noteworthy that CD26 has a key role in immune regulation as a T cell activation molecule and in immune-mediated disorder. All-cause infections were increased after sitagliptin treatment. It is noteworthy that the effects of DPP4 inhibition on the immune system have not been extensively investigated. So far, only routine laboratory safety variables have been measured in published randomised controlled trials. The review summarises present knowledge in the field and suggests some potential directions of future research.

Flow cytometry study of leukocyte function: analytical comparison of methods and their applicability to clinical research.

Perturbations in the redox-based network of cellular regulatory mechanisms have been associated with oxidative-related diseases such as diabetes mellitus. In these situations the redox state of cellular redox systems becomes persistently shifted toward oxidation that may result in a sequence of pathophysiological events. Innate and adaptive immune responses depend on the production of reactive oxygen species and ATP synthesis, which are tightly regulated by the mitochondrial transmembrane potential. Mitochondrial hyperpolarisation is a key mechanism of T-cell life, apoptosis and autoimmunity. The NADPH oxidase of the phagocytic cells of the immune system generates reactive oxygen metabolites during the respiratory burst, but activated B cells also possess NADPH oxidase and reactive oxidants could play regulatory roles in immune function. Cellular thiol levels and the thiol reduction-oxidation process modulate the oxidative metabolism in the cells, transcriptional factor activation of gene expression, lymphocyte proliferation and death. Flow cytometry allows directly characterising and analysing several parameters and functions of intact living cells in a few seconds. Fluorescent lipophilic cations have been used for the measurement of the mitochondrial transmembrane potential. Evaluation of reactive oxygen intermediates generation in neutrophils may be obtained by use of oxidation-sensitive probes. The dye resazurin has been used to quantify mitochondrial activity since considered to act as an intermediate electron acceptor in the electron transport chain between the final reduction of oxygen and cytochrome oxidase. The fluorescence emitted by 5-chloromethyl fluorescein acetate stained cells reflects the total level of free intracellular thiol. In this review we will discuss the possible importance and consequences of evaluating these redox parameters in diabetes pathophysiology. Moreover, we will provide perspectives concerning the varieties of analytical procedures that are capable of measuring them. The advantages and disadvantages of each of these methods are critically discussed particularly in view of their clinical application.

Significant bacteriuria in outpatient diabetic and non-diabetic persons.

AIMS: The prevalence of significant bacteriuria (SB) in diabetes mellitus has not been clearly established. Having previously investigated SB frequency in inpatient diabetic women, we now screened for SB (both asymptomatic and symptomatic forms) in outpatients. METHODS: We examined 511 consecutive outpatients with Type 1 (T1D) or Type 2 diabetes (T2D), and 98 non-diabetic subjects. At least one uncontaminated midstream urine sample was available from 602 subjects: 64 T1D (37 female, age 49 +/- 13 years, diabetes duration 23 +/- 15 years), 441 T2D (212 female, 66 +/- 10 years, 12 +/- 10 years), and 97 healthy control subjects (39 female, 57 +/- 12 years). On the same day, we determined: blood cell count, fasting plasma glucose (FPG), glycated haemoglobin (HbA(1c)), plasma creatinine, urinary creatinine, and urinary albumin excretion (UAE; microg/mg urinary creatinine). RESULTS: The rate of SB was 14.1% in T1D, 9.3% in T2D and 6.2% in control subjects (P = NS). The 50 diabetic patients with SB differed from the 455 diabetic patients without SB in gender (43 male vs. 206 female, P < 0.001), FPG (10.2 +/- 3.6 vs. 9.2 +/- 2.9 mmol/l, P < 0.05), HbA(1c) (7.8 +/- 1.1 vs. 7.5 +/- 1.3%, P < 0.05), and UAE (median 15.6 vs. 7.6 microg/mg, P < 0.01). Eleven diabetic patients with SB had symptoms (vs. 48 without SB, P < 0.05); UAE levels were higher in the 39 asymptomatic diabetic patients with SB than in the 11 symptomatic patients. CONCLUSIONS: The prevalence of SB is similar in outpatient diabetic individuals and in non-diabetic subjects. The main risk factors for SB in diabetic patients were female gender and UAE. The likelihood of asymptomatic SB increased with UAE levels, i.e. with the presence of established microangiopathy. Poor glycaemic control is associated with bacteriuria, either as a cause or consequence of bacteriuria.

Building a bridge between clinical and basic research: the phenotypic elements of familial predisposition to type 1 diabetes.

Familial aggregation has been shown for type 1 diabetes (T1D) although the nature of the factors (environment and/or genetics) responsible remains unclear. Familial clustering of diabetic nephropathy as well as of increased cardiovascular morbidity and early mortality has also been observed. This review describes the nearly 20 years history of our investigation in parallel with contemporary literature. The story is presented from the early years' strong focus on possible markers of T1D nephropathy (urinary albumin, urinary enzymes, erythrocyte Na/Li countertransport, and erythrocyte Na/H exchange) to the last clinical investigations to determine relevant biological markers of familial predisposition to T1D. Our studies of case-families recruited unaffected first-degree relatives of sporadic T1D cases and population-based controls. Unlike multiple-case families, these families are those less likely to carry a strong genetic predisposition. Participants were both interviewed and provided biological material for a detailed functional characterisation of their biochemical phenotype. These studies have initially excluded that the erythrocyte Na/H exchange could be a marker of diabetic nephropathy. On the contrary, NHE activity was significantly higher in T1D family members independently of the presence of renal disease. Basic science knowledge of NHE and its functional implications have also been reviewed. Unexpectedly, we found evidence of increased oxidative stress in nondiabetic normotensive relatives of T1D patients, apart from soluble markers of autoimmunity and despite seemingly intact antioxidant defences. Markers of oxidation were associated with markers of inflammation and we concluded that the familial increase in NHE activity could be ascribed to the direct stimulatory effect of oxidative stress. Relatives showed also immunological hallmarks and cardiovascular abnormalities that were related to indices of oxidative stress and metabolic syndrome. Other peculiarities emerged from measuring the erythrocytes redox system that exports electrons across the cell membrane to external oxidants as a function of cytoplasmic electron donor concentration. This electron transfer might reflect the functional state of membrane proton pumps that modulate intracellular redox levels. The transport system contributed to oxidation in T1D families, whereas in healthy people it protected from oxidation. Furthermore, dietary intake of vitamin C and sporting activities modulated erythrocyte electron transfer efficiency. The contribution of environmental factors was investigated using the European Prospective Investigation of Cancer and Nutrition questionnaires that provided evidence of common unhealthy dietary behaviours, which could even predispose to the development of diabetes and cardiovascular complications, in subjects living in Pisa. However, lifestyle of T1D relatives was indistinguishable from those of controls, except for the higher daily intake of niacin and the lower physical activity levels. No difference in smoking or alcohol consumption emerged among families and controls. The oxidative stress is a non-specific though certain component of pathogenesis at numerous diseases states of aerobic organisms. Although molecular genetic analysis has produced significant progress in T1D phenotype, much remains to be learned about the molecular sequence of events leading from a generic familial pro-oxidant background to a sporadic form of T1D (where oxidative damage targets the insulin-secreting cells).

Dietary habits and nutritional biomarkers in Italian type 1 diabetes families: evidence of unhealthy diet and combined-vitamin-deficient intakes.

OBJECTIVE: Nutritional status and lifestyle can have profound effects on health. To analyse behaviour patterns in population subgroups of public health importance, we compared lifestyle, dietary intake of energy and selected nutrients, and nutritional biomarkers of type 1 diabetes (T1DM) patients and nondiabetic first-degree relatives against control subjects with no family history of T1DM. DESIGN: A cross-sectional study. SETTING: Department of Internal Medicine, University of Pisa, Italy. SUBJECTS: A total of 209 individuals including 38 type 1 patients, 76 relatives, and 95 healthy subjects. INTERVENTIONS: We used the European Prospective Investigation of Cancer and Nutrition questionnaires to assess dietary intake and lifestyle. Anthropometric indices and nutritional biomarkers (such as plasma levels of albumin, iron, lipids, homocysteine, vitamin B9 and vitamin B12 as well as urinary outputs of nitrogen, sodium and potassium) were evaluated. RESULTS: Emerging health issues: (1) In total, 45% of controls were overweight. Increasing age was associated with increasing body mass and decreasing activity in sport in front of an unchanged energy intake. (2) The distribution of energy sources was incorrect. The proportion of caloric intake derived from total fat and cholesterol did not match general guidelines. Total dietary fibre consumption was assessed to be adequate (25 g/day) in only 27% of all the participants. (3) Estimated daily intakes of water-soluble vitamin B9 and fat-soluble vitamin D and vitamin E were deficient in comparison with dietary reference intakes. (4) The prevalence of adoption and maintenance of healthful eating and physical activity habits was higher in women and T1DM patients (probably as a consequence of the medical educational intervention). On the contrary, supportiveness of the family in term of changing the undesirable behaviours at home seemed to fail. CONCLUSIONS: This study provides first evidence indicating unhealthy dietary behaviours, which could even predispose to the development of diabetes and cardiovascular complications, in subjects living in Pisa. The combination of vitamin B9 and vitamin E deprivation could be deleterious for endothelial function, since these antioxidants have been implicated in the modulation of nitric oxide and eicosanoid signalling.

Redox status and immune function in type I diabetes families.

Because abnormalities in redox balance cluster in type I diabetes families and the intracellular thiol redox status seems to modulate immune function, we aimed to investigate the relationship between oxidative stress and immunological features. We measured oxidative markers, serum proinflammatory cytokines, soluble cytokine receptors and subsets of peripheral blood lymphocytes (by varying combinations of CD4, CD8, CD23 or low-affinity IgE receptor, and CD25 or IL-2 receptor) from 38 type I patients, 76 low-risk (i.e. without underlying islet autoimmunity) non-diabetic first-degree relatives of diabetic patients, and 95 healthy subjects. In type I diabetes families, protein and lipid oxidation was confirmed by the presence of reduced sulphhydryl groups, increased advanced oxidation protein products, and increased plasma and erythrocyte malondialdehyde. Relatives had decreased counts of monocytes, of cells co-expressing CD23 and CD25 and of CD25(+) cells in peripheral blood. Patients with TIDM had similar defects and, in addition, showed decreased counts of peripheral CD4(+)CD8(+) lymphocytes and increased serum levels of soluble receptors for interleukin (IL)-6 and IL-2. Abnormal indicators of oxidative stress were related in part to immune abnormalities. In the whole study group, we found a correlation (multiple R 0.5, P < 0.001) of CD23(+)CD25(+) cells with blood counts of monocytes, CD4(+)CD8(+) cells, CD25(+) cells, basal haemolysis and plasma levels of thiols. In type I diabetics, anti-GAD65 antibody levels were associated (multiple R 0.6, P = 0.01) positively with sIL-6R, negatively with duration of diabetes and CD23(+)CD25(+) counts; plasma creatinine correlated positively (multiple R 0.6, P < 0.001) with both sIL-2R and tumour necrosis factor (TNF)-alpha concentration. Our study reports the first evidence that the oxidative stress observed in type I families is related to immunological hallmarks (decreased peripheral numbers of monocytes as well as cells bearing a CD4(+)CD8(+), CD23(+)CD25(+) and CD25(+) phenotype) from which the involvement of some immunoregulatory mechanisms could be suspected. It remains to be elucidated the course of events culminating in the loss of physiological immune homeostasis and disease pathology.

Closing the gap between literature and practice: evaluation of a teaching programme (in the absence of a structured treatment) on both type 1 and type 2 diabetes.

Athough education is considered an integral part of diabetes management, it remains low in the practical priorities of clinicians. We performed the first structured educational intervention in a diabetic outpatient department, where patients were controlled with no provider autonomy support available. We recruited 77 Type 1 (T1DM) and 154 Type 2 diabetic (T2DM) patients as well as 87 matched control subjects. Baseline evaluation included: medical interview; questionnaires concerning diabetes knowledge, diabetes quality of life, state-trait anxiety, depression and general perceived self-efficacy; biochemical examination (fasting blood glucose, HbA1c, lipids, uric acid, urinary glucose and albumin excretion). Of the 231 diabetic patients, 154 agreed to attend an educational course, yet only 101 patients (37 T1DM and 64 T2DM) completed it (intervention group) due to organisational barriers. Intervention and reference (non-participant patients) groups received identical medical care, except that the educational group met with the educator during five teaching sessions. Three to six months after the completion of the course, they underwent a final assessment. Prospective results were: 1) in T1DM, a reduction in HbA1c levels and an increase in plasma HDL cholesterol with no change in drug treatment (the reference group showed no change in HbA1c values despite an increased insulin dose), improved technical skill, knowledge, quality of life and self-efficacy; 2) in T2DM, a reduction in fasting plasma glucose and an improvement in knowledge and quality of life. Analysis of the cross-sectional data at baseline evidenced: 3) the same levels of anxiety, depression and general self-efficacy in diabetic patients compared with healthy control subjects; 4) lower diabetes-specific quality of life associated with established insulin treatment in T2DM; 5) significant gender differences among healthy as well as diabetic subjects in degree of psychological distress. Education by itself is more than simply offering information to people (even in a troubled context) and its infrequent incorporation in practice really contradicts resource efficiency.

Blood levels of total homocysteine in patients with type 1 diabetes (with no complications, diabetic nephropathy and/or retinopathy) and in their non-diabetic relatives.

BACKGROUND AND AIM: It has been reported that plasma homocysteine (Hcy) levels in type 1 diabetes (T1DM) patients without renal involvement are higher, similar to or lower than those in healthy controls. METHODS AND RESULTS: We measured plasma Hcy in 60 controls, 79 type 1 diabetics (23 with retinopathy, 22 with nephropathy) and 73 non-diabetic relatives of 30 probands. The female controls had lower levels than their male counterparts: geometric mean 10.5 vs 13.6 mumol/L, p < 0.001. Among the controls, smokers (n = 20) and ex-smokers (n = 12) had higher Hcy levels than non-smokers (n = 28): 13.2 and 13.2 vs 10.9 mumol/L, p < 0.01. Among the diabetics, high plasma Hcy levels were associated with male gender: 11.9 vs 9.1 mumol/L in women, p < 0.01. The patients without complications had higher plasma glucose and hemoglobin A1c (HbA1c) levels (p < 0.001), and lower plasma Hcy (9.2 mumol/L vs 12.2, p < 0.01) and uric acid levels (p < 0.05) than the controls. The patients with nephropathy and higher levels of Hcy (13.0 mumol/L vs 9.0, p < 0.05), and different levels of creatinine (p < 0.01), uric acid (p < 0.01), fibrinogen (p < 0.05), and urinary albumin (p < 0.001) than those with retinopathy. There was no difference in Hcy levels between the patients' relatives and the controls: 11.9 mumol/L in siblings vs 11.6 mumol/L, 13.5 mumol/L in parents vs 12.1 mumol/L. In the control group, plasma Hcy levels were associated with age, gender and smoking; among the diabetics, they correlated with age, gender, smoking, and plasma creatinine and lipoprotein (a) levels. CONCLUSIONS: 1) male gender and smoking are associated with high Hcy levels in healthy people; 2) plasma Hcy levels are lower in T1DM patients than in healthy people (glomerular hyperfiltration and accelerated hepatic transsulfuration?); 3) high Hcy levels are associated with diabetic nephropathy and plasma creatinine levels; and 4) non-diabetic first-degree relatives of type 1 diabetics have normal plasma Hcy concentrations.

Glycated hemoglobin measurement: intermethod comparison.

Clinical interpretation of changes in serial measurements of patients' HbA1c ought to be based on the knowledge of pre-analytical, analytical and intra-individual sources of variation that affect the results. The detectable change in HbA1c percentage depends on total analytical error. Since we have previously evidenced major problems in the routine use of HPLC, we compared a highly automated glycohemoglobin assay with the reference HPLC to solve the problem. The within- and between-run coefficients of variations ranged from 0.86 to 0.93%, and 2.51 to 2.12%, respectively, for the HPLC, and from 1.07 to 0.95, and 1.61 to 0.99% for the immunoturbidimetric assay. After HbA1c-assay calibration, the quality-control survey report of duplicate determinations performed on 20 consecutive days by both the HPLC and the immunologic method provided the expected mean values of control materials. The assay of 106 blood samples showed a minor yet significant bias of the immunoturbidimetric assay toward lower HbA1c. values (p 0.0001), as previously observed, although the two determination series resulted significantly correlated (r=0.96,p=0.0001). We conclude that the immunoturbidimetric assay is surely accurate, precise, and reproducible, and represents a valid alternative to the reference HPLC assay.

Sodium/hydrogen exchange activity in type 1 diabetes mellitus: the never-ending story.

The amiloride-sensitive Na+/H+ exchanger (NHE) mediates uphill H+ extrusion and thus causes intracellular alkalinization. The NHE plays a major role in pH homeostasis, Na+ absorption, cell volume regulation, and cell proliferation; it is activated by growth factors, mitogens, neurotransmitters, tumor promoters, and others. At intracellular pH (pHi)>7.2-7.4, the system is quiescent; when pHi falls, the rate of H+ - efflux increases in an allosteric manner to reach a maximum around pHi=6.0. The kinetics for external Na+ follows the Michaelis-Menten model with a single, binding site. The effect of intracellular H+ best fits an allosteric model with at least two binding sites. According to the postulate that erythrocyte sodium-lithium countertransport (NLCT) might be one mode of operation of the ubiquitous NHE, and following the trail of previous investigations of NLCT association with hypertension and diabetic nephropathy, several studies have confirmed elevated NHE activity in different cell types in patients with essential hypertension. However, the relation between NHE and either NLCT or hypertension remains unclear and the usefulness of NLCT activity as a risk marker for the development of essential hypertension has been now excluded. On the contrary, few publications have dealt with the physiologic NHE in diabetic nephropathy, and contrasting results have been reported. We have observed an accelerated NHE in essential hypertension and in Type 1 diabetes, however without any relationship with urinary albumin excretion rate. Furthermore, NHE activity increased in non-diabetic first-degree relatives of Type 1 diabetic patients, yet no difference could be observed between relatives of probands with diabetic nephropathy and relatives of probands with normoalbuminuria. Unlike erythrocyte NHE activity, abnormal albumin excretion was a distinctive feature of non-diabetic first-degree relatives of Type 1 diabetic patients with nephropathy. The lack of agreement among Authors, even using both the same cell and the same method, testifies to the difficulty in performing a correct patient selection and uniformly reproducible NHE measurement. We compare individual clinical characteristics among different study populations confirming previous conclusions regarding NLCT in essential hypertension: main determinant for the flux values of NHE seems to be patient selection rather than methodology. A common effort is advisable to collaborate, standardise, compare methodologies, and unify criteria of subject recruitment.

Erythrocyte sodium/hydrogen exchange inhibition by (-) epicatechin.

Epicatechin, a flavonoid belonging to the group of compounds collectively called catechins, have been reported to possess insulin-like properties. Besides their anti-diabetic properties, catechins also show growth inhibition. Since cytosolic pH (pHi) plays a role in cell proliferation and the Na/H exchanger (NHE) is the major pH (pHi) regulatory mechanism, we undertook in vitro studies with human erythrocytes to examine the effect of (-) epicatechin (EC) on the NHE1 isoform. NHE activity was measured in eight healthy volunteers, eight type 1 diabetics, and nine type 2 diabetics, following 30 min incubations at 37 degrees C with either 1 mM epicatechin, 10(-9) M insulin or solvent alone. NHE activity was elevated in both groups of patients (P< 0.05). Epicatechin caused a 93% decrease in Na/H antiport activity in health controls, 89 and 86% in type 1 and type 2 diabetics, respectively (P< 0.001). Insulin caused a 36% decrease in antiport activity only in the type 2 diabetic group (P< 0.05). The strong inhibition of erythrocyte NHE1 (the ubiquitously present isoform) by epicatechin may have important implications. NHE1 inhibition could be one of the major mechanisms underlying the antiproliferative effects of catechins.

Screening for coeliac disease in families of adults with Type 1 diabetes based on serological markers.

The prevalence of coeliac disease (CD) in the adult population is unknown because silent and latent stages do exist. Type 1 diabetes mellitus may be associated with CD because of common genetic background and/or shared pathogenetic mechanisms. We investigated 74 adults with type 1 diabetes (32+/-11 yr, disease duration 13+/-9 yr), 69 parents of diabetic probands (56+/-10 yr), 59 siblings (30+/-11 yr) and 50 healthy controls (35+/-10 yr) for the presence of circulating islet cell antibodies (ICA), anti-glutamic acid decarboxylase antibodies (GADA65), anti-gliadin immunoglobulins A and G (IgA- and IgG-AGA). All patients with raised AGA, performed also IgA anti-endomysium antibody (EmA) indirect immunofluorescence assay. Samples were positive for ICA in 19 diabetics (26%), 4 parents (6%), 4 siblings (7%), 0 controls (p<0.001); for GADA in 34 diabetics (46%), 4 parents (6%), 1 sibling (2%), 0 controls (p<0.001). Twenty-five diabetic patients (34%), 10 parents (14%), 5 siblings (8%), 3 controls (6%) (p<0.001) had raised IgA-AGA (>4.4 mg/l). Four diabetic patients (5%), 5 parents (7%), 0 siblings (0%), 4 controls (8%) had raised IgG-AGA (>18 mg/l). Both IgA- and IgG-AGA were detected in 1 diabetic and 2 parents. The prevalence of ICA, GADA, and IgA-AGA positivity in Type 1 diabetes patients was significantly higher than in controls (p<0.001). Finally, 50 AGA-positive subjects performed EmA test: only 2 of them resulted EmA-positive, a diabetic patient and a sibling. The patient with Type 1 diabetes had a small-bowel biopsy specimen consistent with CD and, as sole evidence of malabsorption, sideropenic anaemia. EmA-positive sibling also showed severe iron deficiency, yet refused endoscopy. We conclude that: 1) CD cannot be diagnosed on the basis of associated IgA- and IgG-AGA alone. Nevertheless, detection of such antibodies is useful, in combination with EmA, in screening for endoscopic biopsy; 2) too high rate of detection of IgA-AGA in Type 1 diabetic patients in comparison with other groups excludes a false positivity of the test itself, while suggests a pathogenetic association of both immunological disorders, perhaps related to abnormal gammadelta TCR-bearing intraepithelial lymphocytes.