Pablo Olmos

Gestational diabetes and pre‐pregnancy overweight: Possible factors involved in newborn macrosomia

Aim:  Good glycemic control in gestational diabetes mellitus (GDM) seems not to be enough to prevent macrosomia (large‐for‐gestational‐age newborns). In GDM pregnancies we studied the effects of glycemic control (as glycosylated hemoglobin [HbA1c]), pre‐pregnancy body mass index (PP‐BMI) and gestational weight gain per week (GWG‐W) on the frequency of macrosomia.

Maternal hypertriglyceridemia: A link between maternal overweight-obesity and macrosomia in gestational diabetes

Infants born from overweight and obese mothers with glucose‐controlled gestational diabetes (GDM) tend to be large‐for‐gestational age (LGA). It is hypothesized that this is due to an excessive rise in maternal triglyceride levels.

Bases fisiopatológicas para una clasificación de la neuropatía diabética

Nowadays, Diabetic Neuropathy (DN) is considered the most common cause of peripheral neuropathy in clinical practice. It can affect sensitive, motor or autonomic nerve fibers, with symmetric, asymmetric, acute or chronic presentations. Due to this variability, with multiple physiopathologic mechanisms involved, a complex clinical classification has been used until recently. The aim of this review is to present a new classification of diabetic neuropathy, based on its physiopathology. It is divided in metabolic microvascular and hypoxic, autoimmune and inflammatory, compressive, secondary to complications ofdiabetes and related to treatment. It must be understood that DN is notjust a functional disease, but a complication of diabetes with molecular and pathological substrates caused by hyperglycemia. Therefore, normalization of blood glucose is a fundamental step towards the successful prevention and treatment of DN.Nowadays, Diabetic Neuropathy (DN) is considered the most common cause of peripheral neuropathy in clinical practice. It can affect sensitive, motor or autonomic nerve fibers, with symmetric, asymmetric, acute or chronic presentations. Due to this variability, with multiple physiopathologic mechanisms involved, a complex clinical classification has been used until recently. The aim of this review is to present a new classification of diabetic neuropathy, based on its physiopathology. It is divided in metabolic microvascular and hypoxic, autoimmune and inflammatory, compressive, secondary to complications of diabetes and related to treatment. It must be understood that DN is not just a functional disease, but a complication of diabetes with molecular and pathological substrates caused by hyperglycemia. Therefore, normalization of blood glucose is a fundamental step towards the successful prevention and treatment of DN.

Fisiopatología de la retinopatía y nefropatía diabéticas

Despite the availability of multiple therapeutic approaches, diabetes mellitus with chronic hyperglycemia remains as the main cause of new cases of blindness and chronic renal failure in the western hemisphere. We herein review the molecular mechanisms by which chronic hyperglycemia causes retinopathy and nephropathy in type I and type 2 diabetic patients. Diabetic retinopathy develops silently along years or decades, producing symptoms only in its very late stages. Its slow development starts with the activation of aldose reductase, shortly followed by the destruction of the retinal pericyte cells, and ends in sudden blindness when vitreous hemorrhage ensues. Nephropathy, on the other hand, centers its pathophysiology in the mesangial cell, that starts as a modified smooth-muscle cell, and turns itself into a myo-fibroblast, produces such amounts of cytoplasm and extracellular protein that strangulates the glomerular capillaries and causes renal failure. After a detailed review of the molecular mechanisms of the aforementioned complications, we conclude that, apart from directing our attention to the emerging medications that are being developed to block these molecular pathways, we should never abandon the struggle for improving the glycemic control of our diabetic patients.

Differences in lung glutathione metabolism may account for rodent susceptibility in elastase-induced emphysema development

Syrian Golden hamsters develop more severe emphysema than Sprague-Dawley rats after intratracheal instillation of the same dose of elastase/body weight. Although species variations in antielastase defenses may largely explain these results, other variables, such as differences in lung antioxidants, cannot be overlooked since oxidative stress modulates antiprotease activity. We propose that elastase instillation might affect lung glutathione (GSH) metabolism differently in these species. Our aim was to study in hamsters and rats, lung glutathione metabolism at different times, from the stage of diffuse alveolar damage to advanced emphysema. We measured total and oxidized glutathione content as well as activity and expression of enzymes related to GSH synthesis and redox cycling: gamma-glutamylcysteine synthetase, glutathione peroxidase, and glutathione reductase. Whereas rats showed no significant changes in these measurements, hamsters showed significant derangement in GSH metabolism early after elastase instillation: 25% fall in total GSH (P < 0.05) with no increase in oxidized glutathione associated with reduced enzyme activities 24 h after elastase [60% for gamma-glutamylcysteine synthetase (P < 0.01), 30% for glutathione peroxidase (P < 0.01), and 75% for glutathione reductase (P < 0.001)]. GSH homeostasis was restored at the end of the first week, involving transient increased expression of these enzymes. We conclude that elastase induces significant alterations in GSH metabolism of hamster lungs and no overall change in rat lungs. Although differences in disease severity may account for our findings, the hamster becomes vulnerable to functional inhibition of alpha(1)-antitrypsin by oxidants and thus, even more susceptible to injury than it would be, considering only its low alpha(1)-antitrypsin level.

Differences in acute lung response to elastase instillation in two rodent species may determine differences in severity of emphysema development

Elastase intratracheal instillation induces early emphysema in rodents. However, Syrian Golden hamsters develop more severe emphysema than Sprague-Dawley rats. We have reported species differences in oxidant/antioxidant balance modulating antiprotease function early after instillation. We now hypothesize that other components of the initial lung response to elastase might also be species-dependent. Sprague-Dawley rats and Syrian Golden hamsters received a single dose of pancreatic elastase (0.55 U/100 g body wt) to study acute lung injury biomarkers. Using serum, lung, and bronchoalveolar lavage fluid (BALF) samples, we evaluated changes in alveolar-capillary permeability, alpha 1-antitrypsin (α(1)-AT) concentration and activity, glutathione content, and proinflammatory cytokines. Rats showed a large increase in alveolar-capillary permeability and few hemorrhagic changes, whereas hamsters exhibited large hemorrhagic changes (P < 0.01) and mild transendothelial passage of proteins. Western blots showed a 30-fold increase in BALF α(1)-AT concentration in rats and only a 7-fold increase in hamsters (P < 0.001), with [α(1)-AT-elastase] complexes only in rats, suggesting differences in antiprotease function. This was confirmed by the α(1)-AT bioassay showing 20-fold increase in α(1)-AT activity in rats and only twofold increase in hamsters (P < 0.001). In rats, results were preceded by a 3-, 60-, and 20-fold increase in IL-6, IL-1β, and TNF-α respectively (P < 0.001). In hamsters, only IL-1β and TNF-α showed mild increases. All parameters studied were back to baseline by 4 days. In conclusion, several components of the initial lung response showed species differences. Cytokine release pattern and functional inhibition of α(1)-AT were the most significant components differing among species and could account for differences in susceptibility to elastase.

Cervical metastases of glucagonoma in a patient with multiple endocrine neoplasia type 1: Report of a case

Multiple endocrine neoplasia type 1 (MEN 1) is a syndrome characterized by tumors of the parathyroid glands, pancreatic islet cells, duodenum, and pituitary gland. We report a case of cervical metastases of glucagonoma with MEN 1. The patient was a 34-year-old woman admitted to our hospital with epigastric pain. Her medical history included two resections of prolactinoma and two upper GI hemorrhages secondary to duodenal ulcers. Computed tomography (CT) showed two hypervascular lesions in the tail of the pancreas and cervical ultrasound showed multiple hypoechogenic ovoid images in the neck. A cervical CT scan confirmed two 15-mm lymph nodes in the left cervical region and 111In-DOTATOC imaging showed focal abnormal somatostatin expression in the pancreatic tail and the cervical nodes. The patient had asymptomatic hypoglycemic episodes, with blood sugar levels as low as 30 mg/dl, which raised our suspicion of MEN 1 associated with pancreatic insulinoma. Thus, we performed a distal pancreatectomy with bilateral cervical dissection and parathyroid gland resection. Histopathological examination revealed 12 pancreatic tumors as well as metastases in four cervical lymph nodes. The resected parathyroid glands had normal structure, suggesting parathyroid hyperplasia. A follow-up CT scan, 18 months after surgery, showed new tumors in the head of the pancreas and in the duodenal wall. A pancreatoduodenectomy was performed and histopathological examination revealed nine nonfunctioning endocrine tumors in the pancreas, one tumor in the duodenal wall, and metastases in two peripancreatic lymph nodes. The patient recovered well and remains asymptomatic.

Fluoxetine impairs insulin secretion without modifying extracellular serotonin levels in MIN6 β-cells.

INTRODUCTION Pancreatic β-cells synthetize and store Serotonin (5-Hydroxytriptamine, 5HT) which is co-released with insulin. It has been proposed that extracellular 5HT binds to specific cell surface receptors and modulate insulin secretion. On the other hand, Selective Serotonin Reuptake Inhibitor (SSRI) fluoxetine seems to reduce Glucose-Stimulated Insulin Secretion (GSIS). However, it is unknown whether this effect results from changes in extracellular 5HT concentration owed to the blockade of 5HT transporter (SERT) or from non-5HT dependent actions. The aims of this work were: 1) to quantify extracellular 5HT levels and GSIS in β-cell lines, 2) to determine whether extracellular 5HT levels and GSIS are changed by fluoxetine or 5-Hydroxytryptophan (5HTP, the immediate 5HT biosynthetic precursor), and 3) to quantify the expression of Slc6a4 gene (encoding SERT) in β-cell lines in relation to other genes involved in 5HT system. MATERIAL AND METHODS β-cell lines MIN6 and RINm5f were subjected to GSIS protocols, after treatment with fluoxetine, 5HTP or 5HT. Insulin and 5HT were quantified by ELISA and HPLC, respectively. Relative mRNA expression was quantified by RT-qPCR. RESULTS MIN6 β-cells secretes 5HT in response to glucose, showing a sharp increase in 5HT release when cells were preloaded with 5HTP. Treatment with 5HT or fluoxetine reduces GSIS. Fluoxetine fails to further increases 5HTP-induced elevation of secreted 5HT. MIN6 β-cells express both isoforms of Tryptophan Hydroxylase (Tph1 and Tph2), and have high expression levels of L-Dopa decarboxylase (Ddc), both enzymes involved in 5HT biosynthetic pathway, but do not express the 5HT transporters Slc6a4 or Slc6a3 (the Dopamine-5HT transporter) genes. CONCLUSION The inhibitory effect of fluoxetine on β-cell glucose stimulated insulin secretion is not mediated by blockage of 5HT transporter through SERT.

La hipótesis de Pedersen no es suficiente: Otros nutrientes además de la glucosa explicarían la macrosomía fetal en pacientes diabéticas gestacionales con sobrepeso y buen control glicémico

Since 1964, the hypothesis of Pedersen has been used to explain fetal macrosomia observed in gestational diabetes mellitus (GDM), by a mechanism involving maternal hyperglycemia--fetal hyperglycemia--fetal hyperinsulinemia. However, since the 1980-89 decade, it is known that pregnant women with pre-gestational overweight not suffering from GDM still have a higher frequency of fetal macrosomia. Furthermore, pregnant women with GDM, despite being subjected to optimal glycemic control, still show unacceptably high frequencies of fetal macrosomia, a phenomenon that is concentrated in pregnancies with overweight or obesity prior to pregnancy. If glucose is not the single nutrient responsible for fetal macrosomia in pregnant women with gestational diabetes that undergo strict glycemic control, other nutrients may cause excessive fetal growth in pre-pregnancy overweight mothers. In this review, we propose that triglycerides (TG) could be responsible for this accelerated fetal growth. If this hypothesis is validated in animal models and clinical studies, then normal and pathological ranges of TG should be defined, and monitoring of triglyceride levels during pregnancy should be advised as a possible new alternative, besides a good glycemic control, for the management of fetal macrosomia in GDM women with overweight prior to pregnancy.

Prolonged Activation of the Htr2b Serotonin Receptor Impairs Glucose Stimulated Insulin Secretion and Mitochondrial Function in MIN6 Cells

Aims Pancreatic β-cells synthesize and release serotonin (5 hydroxytryptamine, 5HT); however, the role of 5HT receptors on glucose stimulated insulin secretion (GSIS) and the mechanisms mediating this function is not fully understood. The aims of this study were to determine the expression profile of 5HT receptors in murine MIN6 β-cells and to examine the effects of pharmacological activation of 5HT receptor Htr2b on GSIS and mitochondrial function. Materials and Methods mRNA levels of 5HT receptors in MIN6 cells were quantified by RT qPCR. GSIS was assessed in MIN6 cells in response to global serotonergic activation with 5HT and pharmacological Htr2b activation or inhibition with BW723C86 or SB204741, respectively. In response to Htr2b activation also was evaluated the mRNA and protein levels of PGC1α and PPARy by RT-qPCR and western blotting and mitochondrial function by oxygen consumption rate (OCR) and ATP cellular content. Results We found that mRNA levels of most 5HT receptors were either very low or undetectable in MIN6 cells. By contrast, Htr2b mRNA was present at moderate levels in these cells. Preincubation (6 h) of MIN6 cells with 5HT or BW723C86 reduced GSIS and the effect of 5HT was prevented by SB204741. Preincubation with BW723C86 increased PGC1α and PPARy mRNA and protein levels and decreased mitochondrial respiration and ATP content in MIN6 cells. Conclusions Our results indicate that prolonged Htr2b activation in murine β-cells decreases glucose-stimulated insulin secretion and mitochondrial activity by mechanisms likely dependent on enhanced PGC1α/PPARy expression.