At the end of the 1980s, it was clearly demonstrated that cells produce nitric oxide and that this gaseous molecule is involved in the regulation of the cardiovascular, immune and nervous systems, rather than simply being a toxic pollutant. In the CNS, nitric oxide has an array of functions, such as the regulation of synaptic plasticity, the sleep-wake cycle and hormone secretion. Particularly interesting is the role of nitric oxide as a Janus molecule in the cell death or survival mechanisms in brain cells. In fact, physiological amounts of this gas are neuroprotective, whereas higher concentrations are clearly neurotoxic.

Currently, there are no data in the literature regarding the pathophysiological mechanisms involved in the rapid resolution of type 2 diabetes after bariatric surgery, which was reported as an additional benefit of the surgical treatment for morbid obesity. With this question in mind, insulin sensitivity, using euglycemic-hyperinsulinemic clamp, and insulin secretion, by the C-peptide deconvolution method after an oral glucose load, together with the circulating levels of intestinal incretins and adipocytokines, have been studied in 10 diabetic morbidly obese subjects before and shortly after biliopancreatic diversion (BPD) to avoid the weight loss interference. Diabetes disappeared 1 week after BPD, while insulin sensitivity (32.96 +/- 4.3 to 65.73 +/- 3.22 mumol . kg fat-free mass(-1) . min(-1) at 1 week and to 64.73 +/- 3.42 mumol . kg fat-free mass(-1) . min(-1) at 4 weeks; P < 0.0001) was fully normalized. Fasting insulin secretion rate (148.16 +/- 20.07 to 70.0.2 +/- 8.14 and 83.24 +/- 8.28 pmol/min per m(2); P < 0.01) and total insulin output (43.76 +/- 4.07 to 25.48 +/- 1.69 and 30.50 +/- 4.71 nmol/m(2); P < 0.05) dramatically decreased, while a significant improvement in beta-cell glucose sensitivity was observed. Both fasting and glucose-stimulated gastrointestinal polypeptide (13.40 +/- 1.99 to 6.58 +/- 1.72 pmol/l at 1 week and 5.83 +/- 0.80 pmol/l at 4 weeks) significantly (P < 0.001) decreased, while glucagon-like peptide 1 significantly increased (1.75 +/- 0.16 to 3.42 +/- 0.41 pmol/l at 1 week and 3.62 +/- 0.21 pmol/l at 4 weeks; P < 0.001). BPD determines a prompt reversibility of type 2 diabetes by normalizing peripheral insulin sensitivity and enhancing beta-cell sensitivity to glucose, these changes occurring very early after the operation. This operation may affect the enteroinsular axis function by diverting nutrients away from the proximal gastrointestinal tract and by delivering incompletely digested nutrients to the ileum.

The primary gene mutated in Charcot-Marie-Tooth type 2A is mitofusin-2 (Mfn2). Mfn2 encodes a mitochondrial protein that participates in the maintenance of the mitochondrial network and that regulates mitochondrial metabolism and intracellular signaling. The potential for regulation of human Mfn2 gene expression in vivo is largely unknown. Based on the presence of mitochondrial dysfunction in insulin-resistant conditions, we have examined whether Mfn2 expression is dysregulated in skeletal muscle from obese or nonobese type 2 diabetic subjects, whether muscle Mfn2 expression is regulated by body weight loss, and the potential regulatory role of tumor necrosis factor (TNF)␣ or interleukin-6. We show that mRNA concentration of Mfn2 is decreased in skeletal muscle from both male and female obese subjects. Muscle Mfn2 expression was also reduced in lean or in obese type 2 diabetic patients. There was a strong negative correlation between the Mfn2 expression and the BMI in nondiabetic and type 2 diabetic subjects. A positive correlation between the Mfn2 expression and the insulin sensitivity was also detected in nondiabetic and type 2 diabetic subjects. To determine the effect of weight loss on Mfn2 mRNA expression, six morbidly obese subjects were subjected to weight loss by bilio-pancreatic diversion. Mean expression of muscle Mfn2 mRNA increased threefold after reduction in body weight, and a positive correlation between muscle Mfn2 expression and insulin sensitivity was again detected. In vitro experiments revealed an inhibitory effect of TNF␣ or interleukin-6 on Mfn2 expression in cultured cells. We conclude that body weight loss upregulates the expression of Mfn2 mRNA in skeletal muscle of obese humans, type 2 diabetes downregulates the expression of Mfn2 mRNA in skeletal muscle, Mfn2 expression in skeletal muscle is directly proportional to insulin sensitivity and is inversely proportional to the BMI, TNF␣ and interleukin-6 downregulate Mfn2 expression and may participate in the dysregulation of Mfn2 expression in obesity or type 2 diabetes, and the in vivo modulation of Mfn2 mRNA levels is an additional level of regulation for the control of muscle metabolism and could provide a molecular mechanism for alterations in mitochondrial function in obesity or type 2 diabetes. Diabetes 54: [2685][2686][2687][2688][2689][2690][2691][2692][2693] 2005

Dietary polyunsaturated fatty acids (PUFA) have effects on diverse physiological processes impacting normal health and chronic diseases, such as the regulation of plasma lipid levels, cardiovascular and immune function, insulin action and neuronal development and visual function. Ingestion of PUFA will lead to their distribution to virtually every cell in the body with effects on membrane composition and function, eicosanoid synthesis, cellular signaling and regulation of gene expression. Cell specific lipid metabolism, as well as the expression of fatty acid-regulated transcription factors, likely play an important role in determining how cells respond to changes in PUFA composition. This review will focus on recent advances on the essentiality of these molecules and on their interplay in cell physiology, leading to new perspective in different therapeutic fields.

OBJECTIVE -We evaluated frozen databases from two 52-week randomized placebocontrolled clinical diabetic neuropathy trials testing two doses of acetyl-L-carnitine (ALC): 500 and 1,000 mg/day t.i.d. RESEARCH DESIGN AND METHODS-Intention-to-treat patients amounted to 1,257 or 93% of enrolled patients. Efficacy end points were sural nerve morphometry, nerve conduction velocities, vibration perception thresholds, clinical symptom scores, and a visual analogue scale for most bothersome symptom, most notably pain. The two studies were evaluated separately and combined.RESULTS -Data showed significant improvements in sural nerve fiber numbers and regenerating nerve fiber clusters. Nerve conduction velocities and amplitudes did not improve, whereas vibration perception improved in both studies. Pain as the most bothersome symptom showed significant improvement in one study and in the combined cohort taking 1,000 mg ALC.CONCLUSIONS -These studies demonstrate that ALC treatment is efficacious in alleviating symptoms, particularly pain, and improves nerve fiber regeneration and vibration perception in patients with established diabetic neuropathy. Diabetes Care 28:96 -101, 2005D iabetic polyneuropathy (DPN) is the most common late complication of diabetes (1) and is commonly associated with neuropathic pain. DPN shows a dynamic natural history with early reversible metabolic abnormalities, which become progressively superimposed by less reversible structural lesions and functional deficits (2).Several clinical diabetic neuropathy trials have been undertaken in the past (rev. in 3,4). Most notably, numerous aldose reductase inhibitor (ARI) trials have been conducted with disappointing results (5-8). Because of adverse drug effects, several ARI developments were abandoned (4,9). Multicenter trials with ␣-lipoic acid have shown small improvements in nerve conduction velocities, but no effects on neuropathy disability scores (4,10). Acetyl-L-carnitine (ALC) is deficient in diabetes (11,12). In preclinical studies, substitution with ALC corrects perturbations of neural Na ϩ /K ϩ -ATPase, myoinositol, nitric oxide (NO), prostaglandins, and lipid peroxidation, all of which play important early pathogenetic roles in DPN (13-16). Long-term prevention and intervention studies in the diabetic rat have revealed preventional and therapeutic effects on peripheral nerve function and structural abnormalities (12,13,16), as well as on endoneurial blood flow (15). Clinical studies have shown that ALC is efficacious in the treatment of painful neuropathies (17)(18)(19). Based on these data, two multicenter, double-blind, placebo-controlled, randomized, 52-week clinical trials were initiated. The design of the two studies was identical, administering ALC at two doses (500 or 1,000 mg) given three times a day (t.i.d.) for 1 year. Efficacy end points included sural nerve morphometry and sensory and motor nerve conduction velocities, vibration perception threshold, clinical symptom scores, and a visual analogue scale for assessment of the most b...

Obesity plays relevant pathophysiological role in the development of health problems, arising as result of complex interaction of genetic, nutritional, and metabolic factors. Due to the role of adipose tissue in lipid and glucose metabolism, and low grade inflammation, it is necessary to classify obesity on the basis of body fat composition and distribution, rather than the simply increase of body weight, and the Body Mass Index. The new term of adiposopathy (''sick fat'') clearly defines the pathogenic role of adipose tissue. Four phenotypes of obese individuals have been described: (1) normal weight obese (NWO); (2) metabolically obese normal weight; (3) metabolically healthy obese; and (4) metabolically unhealthy obese or "at risk" obese. Moreover, sarcopenic obesity has been related to all the phenotypes. The category of normal weight lean, represented by metabolically healthy normal weight has been classified to distinguish from NWO. It is crucial to recommend a bariatric surgery taking into account adiposopathy and sick fat that occurs with the expansion of fat mass, changing the inflammatory and metabolic profile of the patient. Body fat percentage and genetic polymorphism have to be evaluated to personalize the best bariatric surgery intervention.

Surgically induced weight loss is capable of reversing low-grade inflammation, at least partially. The relationships between sCD14, MBL, BPI, and glucose sensitivity, and the role of TNF-alpha in obesity warrant further investigation.

Globalization and global market have contributed to increased consumption of high-fat, energy-dense diets, particularly rich in saturated fatty acids( SFAs). Polyunsaturated fatty acids (PUFAs) regulate fuel partitioning within the cells by inducing their own oxidation through the reduction of lipogenic gene expression and the enhancement of the expression of those genes controlling lipid oxidation and thermogenesis. Moreover, PUFAs prevent insulin resistance by increasing membrane fluidity and GLUT4 transport. In contrast, SFAs are stored in non-adipocyte cells as triglycerides (TG) leading to cellular damage as a sequence of their lipotoxicity. Triglyceride accumulation in skeletal muscle cells (IMTG) derives from increased FA uptake coupled with deficient FA oxidation. High levels of circulating FAs enhance the expression of FA translocase the FA transport proteins within the myocites. The biochemical mechanisms responsible for lower fatty acid oxidation involve reduced carnitine palmitoyl transferase (CPT) activity, as a likely consequence of increased intracellular concentrations of malonyl-CoA; reduced glycogen synthase activity; and impairment of insulin signalling and glucose transport. The depletion of IMTG depots is strictly associated with an improvement of insulin sensitivity, via a reduced acetyl-CoA carboxylase (ACC) mRNA expression and an increased GLUT4 expression and pyruvate dehydrogenase (PDH) activity. In pancreatic islets, TG accumulation causes impairment of insulin secretion. In rat models, beta-cell dysfunction is related to increased triacylglycerol content in islets, increased production of nitric oxide, ceramide synthesis and beta-cell apoptosis. The decreased insulin gene promoter activity and binding of the pancreas-duodenum homeobox-1 (PDX-1) transcription factor to the insulin gene seem to mediate TG effect in islets. In humans, acute and prolonged effects of FAs on glucose-stimulated insulin secretion have been widely investigated as well as the effect of high-fat diets on insulin sensitivity and secretion and on the development of type 2 diabetes.