Interaction between magnesium and methylglyoxal in diabetic polyneuropathy and neuronal models.

OBJECTIVE: The lack of effective treatments against diabetic sensorimotor polyneuropathy demands the search for new strategies to combat or prevent the condition. Because reduced magnesium and increased methylglyoxal levels have been implicated in the development of both type 2 diabetes and neuropathic pain, we aimed to assess the putative interplay of both molecules with diabetic sensorimotor polyneuropathy. METHODS: In a cross-sectional study, serum magnesium and plasma methylglyoxal levels were measured in recently diagnosed type 2 diabetes patients with (n = 51) and without (n = 184) diabetic sensorimotor polyneuropathy from the German Diabetes Study baseline cohort. Peripheral nerve function was assessed using nerve conduction velocity and quantitative sensory testing. Human neuroblastoma cells (SH-SY5Y) and mouse dorsal root ganglia cells were used to characterize the neurotoxic effect of methylglyoxal and/or neuroprotective effect of magnesium. RESULTS: Here, we demonstrate that serum magnesium concentration was reduced in recently diagnosed type 2 diabetes patients with diabetic sensorimotor polyneuropathy and inversely associated with plasma methylglyoxal concentration. Magnesium, methylglyoxal, and, importantly, their interaction were strongly interrelated with methylglyoxal-dependent nerve dysfunction and were predictive of changes in nerve function. Magnesium supplementation prevented methylglyoxal neurotoxicity in differentiated SH-SY5Y neuron-like cells due to reduction of intracellular methylglyoxal formation, while supplementation with the divalent cations zinc and manganese had no effect on methylglyoxal neurotoxicity. Furthermore, the downregulation of mitochondrial activity in mouse dorsal root ganglia cells and consequently the enrichment of triosephosphates, the primary source of methylglyoxal, resulted in neurite degeneration, which was completely prevented through magnesium supplementation. CONCLUSIONS: These multifaceted findings reveal a novel putative pathophysiological pathway of hypomagnesemia-induced carbonyl stress leading to neuronal damage and merit further investigations not only for diabetic sensorimotor polyneuropathy but also other neurodegenerative diseases associated with magnesium deficiency and impaired energy metabolism.

Dietary sugars, not lipids, drive hypothalamic inflammation.

OBJECTIVE: The hypothalamus of hypercaloric diet-induced obese animals is featured by a significant increase of microglial reactivity and its associated cytokine production. However, the role of dietary components, in particular fat and carbohydrate, with respect to the hypothalamic inflammatory response and the consequent impact on hypothalamic control of energy homeostasis is yet not clear. METHODS: We dissected the different effects of high-carbohydrate high-fat (HCHF) diets and low-carbohydrate high-fat (LCHF) diets on hypothalamic inflammatory responses in neurons and non-neuronal cells and tested the hypothesis that HCHF diets induce hypothalamic inflammation via advanced glycation end-products (AGEs) using mice lacking advanced glycation end-products (AGEs) receptor (RAGE) and/or the activated leukocyte cell-adhesion molecule (ALCAM). RESULTS: We found that consumption of HCHF diets, but not of LCHF diets, increases microgliosis as well as the presence of N(ε)-(Carboxymethyl)-Lysine (CML), a major AGE, in POMC and NPY neurons of the arcuate nucleus. Neuron-secreted CML binds to both RAGE and ALCAM, which are expressed on endothelial cells, microglia, and pericytes. On a HCHF diet, mice lacking the RAGE and ALCAM genes displayed less microglial reactivity and less neovasculature formation in the hypothalamic ARC, and this was associated with significant improvements of metabolic disorders induced by the HCHF diet. CONCLUSIONS: Combined overconsumption of fat and sugar, but not the overconsumption of fat per se, leads to excessive CML production in hypothalamic neurons, which, in turn, stimulates hypothalamic inflammatory responses such as microgliosis and eventually leads to neuronal dysfunction in the control of energy metabolism.

Electrical Muscle Stimulation Induces an Increase of VEGFR2 on Circulating Hematopoietic Stem Cells in Patients With Diabetes.

PURPOSE: External electric muscle stimulation (EMS) of the thigh muscles was found to reduce pain resulting from diabetic neuropathy (DN), a vascular complication of diabetes. This study investigated circulating hematopoietic stem cells (HSCs) after EMS treatment. Impaired function of HSCs and the subpopulation endothelial progenitor cells (EPCs), important for neovascularization and endothelial repair, has been associated with DN. METHODS: Twenty-four patients with painful DN were treated 3 times with EMS over a period of 1 week. Blood samples were collected before and after the first EMS treatment. Before a fourth treatment, neuropathic pain was evaluated and a third blood sample was collected. Cells were used for flow cytometry. FINDINGS: Patients with painful DN reported that the pain decreased after 3 times of 1-hour treatments with EMS (Neuropathy Symptom Score: from 8 to 6, P = 0.001; Neuropathy Disability Score: from 5.5 to 5, P = 0.027, n = 24). At the end of the study, diastolic blood pressure had decreased from 80 to 70 mm Hg (P = 0.043), and plasma adrenaline and noradrenaline metabolites metanephrine and normetanephrine were reduced (both P ≤ 0.01; n = 21). A single EMS treatment caused an immediate and transient decrease in the frequency of CD34+ HSCs in circulation (-20%; P < 0.001; n = 27). In 9 of the patients with DN, the proportion of HSCs expressing vascular endothelial growth factor receptor 2 (VEGFR2; defining the HSCs as EPCs) increased by 36% (P = 0.011) after EMS treatment. Proteins required for binding to endothelium (junctional adhesion molecule A and CD31), homing toward hypoxic tissue (C-X-C chemokine receptor type 4), and endothelial differentiation (CD31) were increased on HSCs immediately after EMS treatment. An increased frequency of VEGFR2 expression was also observed on HSCs of 6 healthy control volunteers (34%; P = 0.046) after EMS treatment, but not after sham treatment. IMPLICATIONS: Three EMS treatments decreased symptoms of pain caused by DN and reduced diastolic blood pressure and biomarkers of stress. A single EMS treatment increased molecules mediating attachment and differentiation on the surface of HSCs in circulation. We hypothesize that the EMS-induced increase in surface attachment molecules on the HSCs caused the HSCs to leave circulation and that EMS treatment improves the function of HSCs and EPCs in vivo.

Risk of Malnutrition, Trace Metal, and Vitamin Deficiency Post Roux-en-Y Gastric Bypass--a Prospective Study of 20 Patients with BMI < 35 kg/m².

BACKGROUND: Due to its reliable effects on type 2 diabetes mellitus (T2DM) remission, Roux-en-Y gastric bypass (RYGB) has recently been investigated as a treatment option for nonseverely obese patients with T2DM (body mass index (BMI) <35 kg/m(2)). The purpose of this study was to investigate whether RGYB induces malnutrition of macro- and micronutrients within 24 months in these patients. METHODS: A prospective cohort of 20 patients with longstanding, insulin-dependent T2DM and a BMI of 25-35 kg/m(2) were treated with RYGB. The patients were supplemented with over-the-counter, multivitamin, and micronutrient supplements. Serum concentrations of albumin, vitamins, and trace elements, hemoglobin, and bone density were measured preoperatively and over a 24-month period (DRKS00004605). RESULTS: RYGB did not result in underweight or protein malnutrition. No new onset of deficiencies of water- or fat-soluble vitamins developed over the study period. However, serum selenium, zinc, and ferritin decreased significantly (selenium, 1.17 ± 0.13 to 0.89 ± 0.11 µmol/l, p = 0.018; zinc, 13.9 ± 0.5 to 10.8 ± 0.5 µmol/l, p = 0.012; ferritin, 171.7 ± 26.9 to 31.8 ± 11.2 µg/l, p = 0.018). Hemoglobin remained stable. Vitamin D (13.7 ± 1.8 to 19.1 ± 1.1 ng/ml, p = 0.017) and osteocalcin (15.3 ± 1.7 to 25.4 ± 2.7 ng/ml, p = 0.025) rose significantly, whereas the parathyroid hormone remained stable. Despite increased bone formation, bone density decreased (T score hip, 0.15 ± 0.25 to -0.71 ± 0.34, p = 0.005) resulting in a significant increase in osteopenia rates (18 to 50 %, p = 0.046). CONCLUSIONS: This is the first prospective cohort to investigate malnutrition after RYGB in nonseverely obese patients. These patients are at risk of developing iron, selenium, and zinc deficiencies within 24 months, as well as osteopenia despite an increase in bone formation.

Low-energy diets differing in fibre, red meat and coffee intake equally improve insulin sensitivity in type 2 diabetes: a randomised feasibility trial.

AIMS/HYPOTHESIS: Epidemiological studies have found that a diet high in fibre and coffee, but low in red meat, reduces the risk for type 2 diabetes. We tested the hypothesis that these nutritional modifications differentially improve whole-body insulin sensitivity (primary outcome) and secretion. METHODS: Inclusion criteria were: age 18-69 years, BMI ≥ 30 kg/m(2), type 2 diabetes treated with diet, metformin or acarbose and known disease duration of ≤ 5 years. Exclusion criteria were: HbA1c >75 mmol/mol (9.0%), type 1 or secondary diabetes types and acute or chronic diseases including cancer. Patients taking any medication affecting the immune system or insulin sensitivity, other than metformin, were also excluded. Of 59 patients (randomised using randomisation blocks [four or six patients] with consecutive numbers), 37 (54% female) obese type 2 diabetic patients completed this controlled parallel-group 8-week low-energy dietary intervention. The participants consumed either a diet high in cereal fibre (whole grain wheat/rye: 30-50 g/day) and coffee (≥ 5 cups/day), and free of red meat (L-RISK, n = 17) or a diet low in fibre (≤ 10 g/day), coffee-free and high in red meat (≥ 150 g/day) diet (H-RISK, n = 20). Insulin sensitivity and secretion were assessed by hyperinsulinaemic-euglycaemic clamp and intravenous glucose tolerance tests with isotope dilution. Whole-body and organ fat contents were measured by magnetic resonance imaging and spectroscopy. RESULTS: Whole-body insulin sensitivity increased in both groups (mean [95% CI]) (H-RISK vs L-RISK: 0.8 [0.2, 1.4] vs 1.0 [0.4, 1.7]mg kg(-1) min(-1), p = 0.59), while body weight decreased (-4.8% [-6.1%, -3.5%] vs -4.6% [-6.0%, -3.3%], respectively). Hepatic insulin sensitivity remained unchanged, whereas hepatocellular lipid content fell in both groups (-7.0% [-9.6%, -4.5%] vs -6.7% [-9.5%, -3.9%]). Subcutaneous fat mass (-1,553 [-2,767, -340] cm(3) vs -751 [-2,047; 546] cm(3), respectively) visceral fat mass (-206 [-783, 371] cm(3) vs -241 [-856, 373] cm(3), respectively) and muscle fat content (-0.09% [-0.16%, -0.02%] vs -0.02% [-0.10%, 0.05%], respectively) decreased similarly. Insulin secretion remained unchanged, while the proinflammatory marker IL-18 decreased only after the L-RISK diet. CONCLUSIONS/INTERPRETATION: No evidence of a difference between both low-energy diets was identified. Thus, energy restriction per se seems to be key for improving insulin action in phases of active weight loss in obese type 2 diabetic patients, with a potential improvement of subclinical inflammation with the L-RISK diet. TRIAL REGISTRATION: Clinicaltrials.gov NCT01409330. FUNDING: This study was supported by the Ministry of Science and Research of the State of North Rhine-Westphalia (MIWF NRW), the German Federal Ministry of Health (BMG), the Federal Ministry for Research (BMBF) to the Center for Diabetes Research (DZD e.V.) and the Helmholtz Alliance Imaging and Curing Environmental Metabolic Diseases (ICEMED).

Strontium enhances osseointegration of calcium phosphate cement: a histomorphometric pilot study in ovariectomized rats.

BACKGROUND: Calcium phosphate cements are used frequently in orthopedic and dental surgeries. Strontium-containing drugs serve as systemic osteoblast-activating medication in various clinical settings promoting mechanical stability of the osteoporotic bone. METHODS: Strontium-containing calcium phosphate cement (SPC) and calcium phosphate cement (CPC) were compared regarding their local and systemic effects on bone tissue in a standard animal model for osteoporotic bone. A bone defect was created in the distal femoral metaphysis of 60 ovariectomized Sprague-Dawley rats. CPC and SPC were used to fill the defects in 30 rats in each group. Local effects were assessed by histomorphometry at the implant site. Systemic effects were assessed by bone mineral density (BMD) measurements at the contralateral femur and the spine. RESULTS: Faster osseointegration and more new bone formation were found for SPC as compared to CPC implant sites. SPC implants exhibited more cracks than CPC implants, allowing more bone formation within the implant. Contralateral femur BMD and spine BMD did not differ significantly between the groups. CONCLUSIONS: The addition of strontium to calcium phosphate stimulates bone formation in and around the implant. Systemic release of strontium from the SPC implants did not lead to sufficiently high serum strontium levels to induce significant systemic effects on bone mass in this rat model.

Sustained effects of a mindfulness-based stress-reduction intervention in type 2 diabetic patients: design and first results of a randomized controlled trial (the Heidelberger Diabetes and Stress-study).

OBJECTIVE: To determine whether a mindfulness-based stress reduction (MBSR) intervention is effective for reducing psychosocial distress (i.e., depression, psychosocial stress) and the progression of nephropathy (i.e., albuminuria) and for improving the subjective health status of patients with type 2 diabetes. RESEARCH DESIGN AND METHODS: Patients with type 2 diabetes and microalbuminuria were randomized to a mindfulness-based intervention (n = 53) or a treatment-as-usual control (n = 57) group. The study is designed to investigate long-term outcomes over a period of 5 years. We present data up to the first year of follow-up (FU). RESULTS: At FU, the MBSR group showed lower levels of depression (d = 0.71) and improved health status (d = 0.54) compared with the control group. No significant differences in albuminuria were found. Per-protocol analysis also showed higher stress reduction in the intervention group (d = 0.64). CONCLUSIONS: MBSR intervention achieved a prolonged reduction in psychosocial distress. The effects on albuminuria will be followed up further.

Low but sustained coagulation activation ameliorates glucose-induced podocyte apoptosis: protective effect of factor V Leiden in diabetic nephropathy.

Whereas it is generally perceived to be harmful, enhanced coagulation activation can also convey salutary effects. The high prevalence of the prothrombotic factor V Leiden (FVL) mutation in whites has been attributed to a positive selection pressure (eg, resulting from reduced blood loss or improved survival in sepsis). The consequences of enhanced coagulation activation, as observed in FVL carriers, on microvascular diabetic complications remain unknown. We therefore investigated the role of FVL in diabetic nephropathy. In heterozygous or homozygous diabetic FVL mice, albuminuria and indices of diabetic nephropathy were reduced compared with diabetic wild-type mice. This was associated with reduced glomerular apoptosis and preservation of podocytes in diabetic FVL-positive mice. In vitro, low-dose thrombin (50pM) prevented, whereas high-dose thrombin (20nM) aggravated, glucose-induced apoptosis in podocytes. In diabetic patients, the FVL mutation, but not the plasminogen activator inhibitor-1 4G/5G polymorphism, is associated with reduced albuminuria, which is consistent with a nephroprotective role of low but sustained thrombin generation. Consistently, anticoagulation of diabetic FVL-positive mice with hirudin abolished the nephroprotective effect. These results identify a nephroprotective function of low but sustained thrombin levels in FVL carriers, supporting a dual, context-dependent function of thrombin in chronic diseases.

External electric muscle stimulation improves burning sensations and sleeping disturbances in patients with type 2 diabetes and symptomatic neuropathy.

OBJECTIVE: External muscle stimulation (EMS) of the thighs was previously shown to have beneficial effects in a pilot study on painful diabetic neuropathy. However, differential effects on specific symptoms of neuropathy as well as determinants of treatment response have not been described. DESIGN: Ninety-two type 2 diabetes patients with different neuropathic symptoms were included in a prospective uncontrolled trial. Patients were treated twice a week for 4 weeks. Symptoms were graded on numeric scales at baseline, before the second and the eighth visit. RESULTS: Seventy-three percent of the participants reported marked improvement of symptoms. Subjective treatment response was positively and independently associated with symptom intensity but independent of disease extent, metabolic factors, age, or gender. Total symptoms graded by patients on numerical scales decreased significantly after 4 weeks of treatment. Patients in the upper tertile of symptom intensity showed significant improvement of paresthesia, pain, numbness and most pronounced for burning sensations and sleeping disturbances. CONCLUSIONS: In an uncontrolled setting, EMS seems to be an effective treatment for symptomatic neuropathy in patients with type 2 diabetes, especially in patients with strong symptoms.

Effects of supplementation with alpha-lipoic acid on exercise-induced activation of coagulation.

Physical exercise leads to minor activation of blood coagulation, which appears to be balanced by a concomitant activation of the fibrinolytic system. The mechanisms underlying this physiological phenomenon are still unknown. To evaluate the role of oxidative stress for exercise-induced activation of coagulation, we investigated if supplementation with alpha -lipoic acid (LA) as an antioxidant reduces the hemostatic response to exercise. Ten young men (age, 25 +/- 4 years; maximal oxygen consumption [V o 2 max], 61 +/- 6 mL/(kg min) [mean +/- SD]) were subjected to a 1-hour run on a treadmill at a velocity corresponding to an oxygen demand of 75% to 80% of maximum (anaerobic threshold). Exercise testing was repeated in the same subjects after supplementation with LA (1200 mg/d PO) for 10 days. Molecular markers of thrombin (prothrombin fragment 1 + 2, thrombin-antithrombin complexes) and fibrin formation (fibrinopeptide A) as well as markers of the fibrinolytic activity (tissue-plasminogen activator, plasmin-antiplasmin complexes, d -dimers) and of lipid peroxidation (malondialdehyde) were determined before and immediately after exercise. Supplementation therapy with LA had no effect on hemostatic and fibrinolytic variables either at rest or in response to exercise. Likewise, concentrations of malondialdehyde at rest and after exercise were not influenced by LA. In summary, the hemostatic response to exercise is not affected by supplementation with LA in young healthy male individuals. The role of oxidative stress for exercise-induced activation of coagulation has to be defined in further studies.