Stem cell factor protects against neuronal apoptosis by activating AKT/ERK in diabetic mice

Neuronal apoptosis occurs in the diabetic brain due to insulin deficiency or insulin resistance, both of which reduce the expression of stem cell factor (SCF). We investigated the possible involvement of the activation of the MAPK/ERK and/or AKT pathways in neuroprotection by SCF in diabetes. Male C57/B6 mice (20-25 g) were randomly divided into four groups of 10 animals each. The morphology of the diabetic brain in mice treated or not with insulin or SCF was evaluated by H&E staining and TUNEL. SCF, ERK1/2 and AKT were measured by Western blotting. In diabetic mice treated with insulin or SCF, there was fewer structural change and apoptosis in the cortex compared to untreated mice. The apoptosis rate of the normal group, the diabetic group receiving vehicle, the diabetic group treated with insulin, and the diabetic group treated with SCF was 0.54 ± 0.077%, 2.83 ± 0.156%, 1.86 ± 0.094%, and 1.78 ± 0.095% (mean ± SEM), respectively. SCF expression was lower in the diabetic cortex than in the normal cortex; however, insulin increased the expression of SCF in the diabetic cortex. Furthermore, expression of phosphorylated ERK1/2 and AKT was decreased in the diabetic cortex compared to the normal cortex. However, insulin or SCF could activate the phosphorylation of ERK1/2 and AKT in the diabetic cortex. The results suggest that SCF may protect the brain from apoptosis in diabetes and that the mechanism of this protection may, at least in part, involve activation of the ERK1/2 and AKT pathways. These results provide insight into the mechanisms by which SCF and insulin exert their neuroprotective effects in the diabetic brain.

Effects of strain and age on ear wound healing and regeneration in mice

Round holes in the ears of MRL mice tend to close with characteristics of regeneration believed to be absent in other mouse strains (e.g., C57BL/6). We evaluated the kinetics and the histopathology of ear wound closure in young (8 weeks old) C57BL/6 and BALB/c mice. We also used middle-aged (40 weeks old) C57BL/6 mice to evaluate the influence of aging on this process. A circular through-and-through hole was made in the ear, photographs were taken at different times after injury and wound area was measured with digital analysis software. The percentages of closed area measured on day 100 were: 23.57 ± 8.66% for young BALB/c mice, 56.47 ± 7.39% for young C57BL/6 mice, and 75.31 ± 23.65% for middle-aged C57BL/6 mice. Mice were sacrificed on days 1, 3, 5, 25, 44, and 100 for histological evaluation with hematoxylin and eosin, Gomori’s trichrome, periodic acid-Schiff, or picrosirius red staining. In young mice of both strains, healing included re-epithelialization, chondrogenesis, myogenesis, and collagen deposition. Young C57BL/6 and BALB/c mice differed in the organization of collagen fibers visualized using picrosirius-polarization. Sebaceous glands and hair follicles regenerated and chondrogenesis was greater in young C57BL/6 mice. In middle-aged C57BL/6 mice all aspects of regeneration were depressed. The characteristics of regeneration were present during ear wound healing in both young BALB/c and young C57BL/6 mice although they differed in intensity and pattern. Greater ear wound closure in middle-aged C57BL/6 mice was not correlated with regeneration.

Effect of gallium-arsenide laser, gallium-aluminum-arsenide laser and healing ointment on cutaneous wound healing in Wistar rats

This study determined the effects of gallium-aluminum-arsenide laser (GaAlAs), gallium-arsenide laser (GaAs) and Dersani® healing ointment on skin wounds in Wistar rats. The parameters analyzed were: type I and III collagen fiber concentrations as well as the rate of wound closure. Five wounds, 12 mm in diameter, were made on the animals’ backs. The depth of the surgical incision was controlled by removing the epithelial tissue until the dorsal muscular fascia was exposed. The animals were anesthetized with ketamine and xylazine via intraperitoneal injection. The rats were randomly divided into five groups of 6 animals each, according to the treatment received. Group 1 (L4): GaAs laser (4 J/cm²); group 2 (L30): GaAlAs laser (30 J/cm²); group 3 (L60): GaAlAs laser (60 J/cm²); group 4 (D): Dersani® ointment; group 5 (control): 0.9% saline. The applications were made daily over a period of 20 days. Tissue fragments were stained with picrosirius to distinguish type I collagen from type III collagen. The collagen fibers were photo-documented and analyzed using the Quantum software based on the primary color spectrum (red, yellow and blue). Significant results for wound closing rate were obtained for group 1 (L4), 7.37 mm/day. The highest concentration of type III collagen fibers was observed in group 2 (L30; 37.80 ± 7.10%), which differed from control (29.86 ± 5.15%) on the 20th day of treatment. The type I collagen fibers of group 1 (L4; 2.67 ± 2.23%) and group 2 (L30; 2.87 ± 2.40%) differed significantly from control (1.77 ± 2.97%) on the 20th day of the experiment.

Plasma concentrations and placental immunostaining of interleukin-10 and tumornecrosis factor-α as predictors of alterations in the embryo-fetal organism and the placental development of diabetic rats

Interleukin-10 (IL-10) appears to be the key cytokine for the maintenance of pregnancy and inhibits the secretion of inflammatory cytokines such as tumor necrosis factor-α (TNF-α). However, there are no studies evaluating the profile of these cytokines in diabetic rat models. Thus, our aim was to analyze IL-10 and TNF-α immunostaining in placental tissue and their respective concentrations in maternal plasma during pregnancy in diabetic rats in order to determine whether these cytokines can be used as predictors of alterations in the embryo-fetal organism and in placental development. These parameters were evaluated in non-diabetic (control; N = 15) and Wistar rats with streptozotocin (STZ)-induced diabetes (N = 15). At term, the dams (100 days of life) were killed under anesthesia and plasma and placental samples were collected for IL-10 and TNF-α determinations by ELISA and immunohistochemistry, respectively. The reproductive performance was analyzed. Plasma IL-10 concentrations were reduced in STZ rats compared to controls (7.6 ± 4.5 vs 20.9 ± 8.1 pg/mL). The placental scores of immunostaining intensity did not differ between groups (P > 0.05). Prevalence analysis showed that the IL-10 expression followed TNF-α expression, showing a balance between them. STZ rats also presented impaired reproductive performance and reduced plasma IL-10 levels related to damage during early embryonic development. However, the increased placental IL-10 as a compensatory mechanism for the deficit of maternal regulation permitted embryo development. Therefore, the data suggest that IL-10 can be used as a predictor of changes in the embryo-fetal organism and in placental development in pregnant diabetic rats.

Correlation between total nitrite/nitrate concentrations and monoamine oxidase (types A and B) and semicarbazide-sensitive amine oxidase enzymatic activities in human mesenteric arteries from non-diabetic and type 2 diabetic patients

The aim of this study was to determine the correlation between total nitrite/nitrate concentrations (NOx) and the kinetic parameters of monoamine oxidase enzymes (MAO-A and MAO-B) and semicarbazide-sensitive amine oxidase (SSAO) in human mesenteric arteries. Arteries were from non-diabetic and type 2 diabetic patients with sigmoid or rectum carcinoma for whom surgery was the first option and who were not exposed to neo-adjuvant therapy. Segments of human inferior mesenteric arteries from non-diabetic (61.1 ± 8.9 years old, 7 males and 5 females, N = 12) and type 2 diabetic patients (65.8 ± 6.2 years old, 8 males and 4 females, N = 12) were used to determine NOx concentrations and the kinetic parameters of MAO-A, MAO-B and SSAO by the Griess reaction and by radiochemical assay, respectively. The NOx concentrations in arteries from diabetic patients did not differ significantly from those of the non-diabetic group (10.28 ± 4.61 vs 10.71 ± 4.32 nmol/mg protein, respectively). In the non-diabetic group, there was a positive correlation between NOx concentrations and MAO-B parameters: Km (r = 0.612, P = 0.034) and Vmax (r = 0.593, P = 0.042), and a negative correlation with the SSAO parameters: Km (r = -0.625, P = 0.029) and Vmax (r = -0.754, P = 0.005). However, in the diabetic group no correlation was found between NOx concentrations and the three kinetic parameters of the enzymes. These results suggest an important function of sympathetic nerves and vascular NOx concentrations in arteries of non-diabetic patients. Thus, these results confirm the importance of a balance between oxidants and antioxidants in the maintenance of vascular homeostasis to prevent oxidative stress.

GUAR GUM EFFECTS ON BLOOD SERUM LIPIDS AND GLUCOSE CONCENTRATIONS OF WISTAR DIABETIC RATS1

The effects of guar gum derived from the endosperm of Cyamopsis tetragonoloba (75% soluble fiber, 7.6% insoluble fiber, 2.16% crude protein, 0.78% total lipids, 0.54% ash and 9.55% moisture) on diabetic rats were studied concerning food intake, body weight gain, blood serum cholesterol, triacylglycerols, glucose, LDL-, and HDL-cholesterol concentrations. The effect of gum on indexes of protein absorption and utilization was also investigated. Diets containing 0%, 10% and 20% (w/w) guar gum were fed to diabetic rats for 28 days. In spite of the fact that diabetes elevated blood lipids in all animals, guar gum diet significantly decreased (p <0.05) serum concentrations of cholesterol and triacylglycerols. Furthermore, a concomitant increase in HDL-cholesterol with a substancial elevation of the HDL/LDL cholesterol ratio was found. The most significant result in this assay was the drastic reduction of blood glucose in diabetic rats treated with guar gum diet. The gum promoted a general improvement in the condition of the diabetic rats, in body weight gain and indexes of protein absorption and utilization. The results of this research suggest that guar gum, at concentrations equal to or higher than 10%, should be effective in the treatment of hypercholesterolemia and diabetes, in humans.

Effects of different concentrations of passion fruit peel (Passiflora edulis) on the glicemic control in diabetic rat

Diabetes mellitus, an endocrine disorder, is the major cause of morbidity in developing countries, and it is considered the fourth leading cause of death worldwide. The conventional therapy for diabetes is insulin treatment. The peel of the Passion fruit is rich in fiber and prevents the absorption of carbohydrates, and thus can control and reduce the blood sugar rate. The objective of this study was to analyze the effect of the passion fruit peel flour on the glicemia of diabetic rats, as well as to study the probable action mechanisms. Wistar rats were used in the experiment and were offered the flours of the passion fruit peel in three concentrations: 5, 10, and 15%, and a casein diet as control. The most significant effect on the reduction of the glicemic rate was obtained with the 5% diet. The best values of hepatic glycogen were found in the 5 and 10% diets. The results of this study suggest that the 5% passion fruit flour diet was the one that provided the best reduction of blood glucose levels (59%) and the higher increase of the hepatic glycogen level (71%). The conversion of blood glucose into hepatic glycogen was considered the probable action mechanism involved.

The role of extracellular matrix macromolecules in cancer and diabetic macroangiopathy – with special reference to decorin and hyaluronan

The central role of extracellular matrix (ECM) macromolecules in diseases such as cancer and atherosclerotic vascular diseases including diabetic macroangiopathy is indisputable. Decorin and hyaluronan (HA) represent vital ECM macromolecules in the microenvironment of cells and are centrally involved in human cancer and cardiovascular biology. In cancer, decorin is considered to play a tumor suppressive role. However, there is some discrepancy whether malignant cells express it. Regarding HA, its contribution to the development of atherosclerotic vascular diseases has been well established. Nevertheless, the precise role of HA in arterial narrowing associated with diabetes is not known. The present study focused on two vital ECM macromolecules, namely decorin and HA. First, decorin expression was studied in human tumorigenesis. Furthermore, the effect of adenovirus-mediated decorin transduction on selected cancer cell lines was investigated. The results invariably showed that cancer cells completely lacked decorin expression. The study also demonstrated that transducing cancer cells with decorin adenoviral vector markedly inhibited their malignant behavior. In line with this, a strong induction of decorin expression in normal human embryonic stem cells (hESCs), but not in abnormal hESCs was observed during their differentiation. Secondly, the significance of HA in the development of diabetic macroangiopathy in response to hyperglycemia was evaluated. Results showed that the synthesis of HA by vascular smooth muscle cells was significantly increased in response to high glucose concentration. This increase was associated with the diminished ability of the cells to contract collagen-rich matrix suggesting that HA participates in the disturbed vascular remodeling of diabetic patients. The results of this study support endeavours to develop novel ECM macromolecule -based therapies targeting cancer and cardiovascular diseases.

Dietary Strategies to Optimize Wound Healing after Periodontal and Dental Implant Surgery: An Evidence-Based Review

Methods to optimize healing through dietary strategies present an attractive option for patients, such that healing from delicate oral surgeries occurs as optimally as possible with minimal patient-meditated complications through improper food choices. This review discusses findings from studies that have investigated the role of diet, either whole foods or individual dietary components, on periodontal health and their potential role in wound healing after periodontal surgery. To date, research in this area has largely focused on foods or individual dietary components that may attenuate inflammation or oxidant stress, or foster de novo bone formation. These studies suggest that a wide variety of dietary components, including macronutrients and micronutrients, are integral for optimal periodontal health and have the potential to accelerate oral wound healing after periodontal procedures. Moreover, this review provides guidance regarding dietary considerations that may help a patient achieve the best possible outcome after a periodontal procedure.

Insulino-mimetic and anti-diabetic effects of zinc

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

The parenting styles and the feeding practices of parents of diabetic adolescents

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Neuron-Derived Semaphorin 3A is an Early Inducer of Vascular Permeability in Diabetic Retinopathy

La détérioration de la barrière hémato rétinienne et l'oedème maculaire consécutif est une manifestation cardinale de la rétinopathie diabétique (RD) et la caractéristique clinique la plus étroitement associée à la perte de la vue. Alors que l'oedème maculaire affecte plus de 25% des patients souffrant de diabète, les modalités de traitement actuellement disponibles tels que les corticostéroïdes administrés localement et les thérapies anti-VEGF récemment approuvés présentent plusieurs inconvénients. Bien que le lien entre une rupture de l’unité neuro-vasculaire et la pathogénèse de la RD ait récemment été établi, l’influence de la signalisation neuro-vasculaire sur la vasculopathie oculaire diabetique a jusqu’à présent reçu peu d’attention. Ici, à l’aide d’ètudes humaines et animales, nous fournissons la première preuve du rôle essentiel de la molécule de guidage neuronale classique Sémaphorine 3A dans l’instigation de la perméabilité vasculaire maculaire pathologique dans le diabète de type 1. L’étude de la dynamique d’expression de Sémaphorine 3A révèle que cette dernière est induite dans les phases précoces hyperglycèmiques du diabète dans la rétine neuronale et participe à la rupture initiale de la fonction de barrière endothéliale. En utilisant le modèle de souris streptozotocine pour simuler la rétinopathie diabétique humaine, nous avons démontré par une série d’approches analogue que la neutralisation de Sémaphorine 3A empêche de façon efficace une fuite vasculaire rétinienne. Nos résultats identifient une nouvelle cible thérapeutique pour l’oedème maculaire diabétique en plus de fournir d’autres preuves de communication neuro-vasculaire dans la pathogènese de la RD.

Implications physiopathologiques de la Nestine lors du remodelage pulmonaire et cardiaque à la suite de l’infarctus du myocarde, du diabète et de l’hypertension pulmonaire

Il est reconnu que la protéine filamenteuse intermédiaire Nestine est exprimée lors du processus de cicatrisation et du remodelage fibrotique. De plus, nous avons identifié l’expression de la Nestine au sein de deux populations distinctes qui sont directement impliquées dans les réponses de fibroses réparative et réactive. Ainsi, une population de cellules souches neurales progénitrices résidentes du coeur de rat adulte exprime la Nestine et a été identifiée à titre de substrat de l’angiogenèse et de la neurogenèse cardiaque. Également, la Nestine est exprimée par les myofibroblastes cicatriciels cardiaques et il a été établi que la protéine filamenteuse intermédiaire joue un rôle dans la prolifération de ces cellules. Ainsi, l’objectif général de cette thèse était de mieux comprendre les évènements cellulaires impliqués dans la réponse neurogénique des cellules souches neurales progénitrices résidentes cardiaques Nestine(+) (CSNPRCN(+)) lors de la fibrose réparative cardiaque et d’explorer si l’apparition de fibroblastes Nestine(+) est associée avec la réponse de fibrose réactive secondaire du remodelage pulmonaire. Une première publication nous a permis d’établir qu’il existe une régulation à la hausse de l’expression de la GAP43 (growth associated protein 43) et que cet événement transitoire précède l’acquisition d’un phénotype neuronal par les CSNPRCN(+) lors du processus de cicatrisation cardiaque chez le rat ayant subi un infarctus du myocarde. De plus, la surimposition de la condition diabétique de type 1, via l’injection unique de Streptozotocine chez le rat, abolit la réponse neurogénique des CSNPRCN(+), qui est normalement induite à la suite de l’ischémie cardiaque ou de l’administration de 6-hydroxydopamine. Le second article a démontré que le développement aigu de la fibrose pulmonaire secondaire de l’infarctus du myocarde chez le rat est associé avec une augmentation de l’expression protéique de la Nestine et de l’apparition de myofibroblastes pulmonaires Nestine(+). Également, le traitement de fibroblastes pulmonaires avec des facteurs de croissances peptidiques pro-fibrotiques a augmenté l’expression de la Nestine par ces cellules. Enfin, le développement initial de la condition diabétique de type 1 chez le rat est associé avec une absence de fibrose réactive pulmonaire et à une réduction significative des niveaux protéiques et d’ARN messager de la Nestine pulmonaire. Finalement, la troisième étude représentait quant à elle un prolongement de la deuxième étude et a alors examiné le remodelage pulmonaire chronique chez un modèle établi d’hypertension pulmonaire. Ainsi, les poumons de rats adultes mâles soumis à l’hypoxie hypobarique durant 3 semaines présentent un remodelage vasculaire, une fibrose réactive et une augmentation des niveaux d’ARN messager et de la protéine Nestine. De plus, nos résultats ont démontré que la Nestine, plutôt que l’alpha-actine du muscle lisse, est un marqueur plus approprié des diverses populations de fibroblastes pulmonaires activés. Également, nos données suggèrent que les fibroblastes pulmonaires activés proviendraient en partie de fibroblastes résidents, ainsi que des processus de transition épithélio-mésenchymateuse et de transition endothélio-mésenchymateuse. Collectivement, ces études ont démontré que des populations distinctes de cellules Nestine(+) jouent un rôle majeur dans la fibrose réparative cardiaque et la fibrose réactive pulmonaire.

Spectral Characteristics of the Blood of Streptozotocin Diabetic Rats using Photoacoustic Technique

Optical absorption characteristics of rat blood affected by diabetes has been studied using photoacoustic (PA) technique. PA spectrum of blood depends on the molecular structure of haemoglobin. The peak value ratio ylQ increases with increase in the diabetic state. Externally added glucose to normal blood does not show any increase in y//3 ratio as seen in the diabetic condition . The increase in yl,8 ratio may be due to the decrease in DPG level and the resultant shift from R -> T conformation of majority of diabetic haemoglobin.