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The relationship between glucose metabolism byproduct, D-lactate, and vascular endothelial cell dysfunction and possible role in diabetes2013 June 1900 (has links)
Diabetes mellitus is a chronic disease associated with vascular complications. Vascular endothelial dysfunction caused by increased endothelial cell apoptosis contributes to diabetic cardiovascular complications. The glucose metabolic by-product, D-lactate, is elevated in diabetics and it is unknown whether it contributes to endothelial cell apoptosis. We hypothesized that diabetic D-lactate levels induce apoptosis in human vascular endothelial cells (HUV-EC-C).
HUV-EC-C were incubated with 0.2 mM D-lactate (DLA) and mRNA expression of PI3K/AKT pathway members (AKT1, Bcl-2, BAD, eNOS, PI3K) were measured using Quantitative RT-PCR. DLA downregulated all genes at 6 and 24 hours, followed by increase in expression after 48 hours except PI3K, which remained below control. To further investigate apoptosis, the Human Apoptosis PCR Array was used and expression of all proapoptotic genes (TNF family members) and antiapoptotic genes (IAP family members) were decreased and increased, respectively, at 24 hours followed by an increase and decrease, respectively, at 48 hours. Caspase activity, measured using the Caspase-Glo® 3/7 Assay after HUV-EC-C exposure to 0.2 mM DLA alone or in combination with 20 mM glucose (GLU) or 5 µM methylglyoxal (MG), was increased after 1, 72, and 96 hours. Furthermore, to know whether DLA (0.2 mM) and DLA (0.2 mM), GLU (20 mM) and MG (5 µM) combined cause changes in cellular energy metabolism, creatine (Cr) and high-energy phosphate substrates (CrP, ATP, ADP, AMP) were quantified using HPLC and no changes were observed. We further measured ROS production in HUV-EC-C treated with 0.06-2 mM DLA alone or 0.2 mM DLA with 5-30 mM GLU or 5-160 μM MG. All DLA concentrations increased ROS production by 160% to 216%. DLA with GLU or MG significantly increased ROS production compared to GLU or MG alone. Lastly, D-lactate dehydrogenase (D-LDH) expression was determined using Quantitative RT-PCR and D-LDH was not detected in HUV-EC-C.
In conclusion, DLA altered expression of different pro- and anti-apoptotic genes in HUV-EC-C. Furthermore, exposure of HUV-EC-C to DLA levels typically present in diabetics resulted in time-dependent changes in caspase activity, possibly due to excessive ROS production. Whether these changes eventually lead to endothelial dysfunction in diabetes needs further investigation.
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Knowledge of patients and family members regarding diabetes mellitus and its treatmentShilubane, Hildah N. 30 November 2003 (has links)
Diabetes mellitus is a chronic disease affecting millions of people worldwide. The degenerative changes caused by diabetes can, however, be controlled through the correct treatment.
The outcome of diabetes mellitus depends mainly on the patient's self-management. Health professionals therefore have a major responsibility to assist patients to acquire the essential knowledge, skills and attitudes for self-management. The purpose of this study was to identify diabetic patients and family members' knowledge and views about diabetes mellitus and its treatment regimen.
A quantitative descriptive survey design was used. Questionnaires were used to collect data from a convenient sample of diabetic patients and family members. Data was analysed by a computer program called Statistical Package for Social Sciences. Findings revealed that patients and family members lack adequate knowledge on diabetes mellitus and its treatment. Recommendations regarding the required information and assistance to be given to diabetic patients and their family members were formulated. / Health Studies / (MA (Health Studies))
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Knowledge of patients and family members regarding diabetes mellitus and its treatmentShilubane, Hildah N. 30 November 2003 (has links)
Diabetes mellitus is a chronic disease affecting millions of people worldwide. The degenerative changes caused by diabetes can, however, be controlled through the correct treatment.
The outcome of diabetes mellitus depends mainly on the patient's self-management. Health professionals therefore have a major responsibility to assist patients to acquire the essential knowledge, skills and attitudes for self-management. The purpose of this study was to identify diabetic patients and family members' knowledge and views about diabetes mellitus and its treatment regimen.
A quantitative descriptive survey design was used. Questionnaires were used to collect data from a convenient sample of diabetic patients and family members. Data was analysed by a computer program called Statistical Package for Social Sciences. Findings revealed that patients and family members lack adequate knowledge on diabetes mellitus and its treatment. Recommendations regarding the required information and assistance to be given to diabetic patients and their family members were formulated. / Health Studies / (MA (Health Studies))
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Semicarbazide-sensitive Amine Oxidase (SSAO) – Regulation and Involvement in Blood Vessel Damage with Special Regard to Diabetes : A Study on Mice Overexpressing Human SSAOGöktürk, Camilla January 2004 (has links)
<p>Semicarbazide-sensitive amine oxidase (SSAO, EC 1.4.3.6) belongs to a family of copper-containing amine oxidases. SSAO exists as a membrane bound protein in endothelial-, smooth muscle-, and adipose cells as well as soluble in plasma. SSAO catalyses oxidative deamination of primary monoamines, which results in the production of corresponding aldehydes, hydrogen peroxide and ammonia. These compounds are very reactive and potentially cytotoxic, and are able to induce vascular damage if produced in high levels. Patients with diabetes mellitus, and with diabetic complications in particular, have a higher SSAO activity in plasma compared to healthy controls. It has therefore been speculated that high SSAO activity is involved in the development of vascular complications associated with diabetes. The aim of this thesis is to investigate the importance of SSAO in the development of disorders of a vascular origin. We have studied the transcriptional regulation of the SSAO gene, by inducing diabetes in NMRI and in transgenic mice, overexpressing the human form of SSAO in smooth muscle cells. We found that the increase in SSAO activity in diabetes is accompanied by reduced mRNA levels of the endogenous mouse gene, suggesting a negative feedback on the transcription of the SSAO gene. In addition, the transgenic mice exhibited an abnormal phenotype in the elastic tissue of aorta and renal artery. These mice have a lower mean artery pressure and an elevated pulse pressure. These results indicate that high SSAO activity in smooth muscle cells is associated with a change in the morphology of large arteries. This is likely contributing to the development of vascular complications in diabetes.</p>
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Semicarbazide-sensitive Amine Oxidase (SSAO) – Regulation and Involvement in Blood Vessel Damage with Special Regard to Diabetes : A Study on Mice Overexpressing Human SSAOGöktürk, Camilla January 2004 (has links)
Semicarbazide-sensitive amine oxidase (SSAO, EC 1.4.3.6) belongs to a family of copper-containing amine oxidases. SSAO exists as a membrane bound protein in endothelial-, smooth muscle-, and adipose cells as well as soluble in plasma. SSAO catalyses oxidative deamination of primary monoamines, which results in the production of corresponding aldehydes, hydrogen peroxide and ammonia. These compounds are very reactive and potentially cytotoxic, and are able to induce vascular damage if produced in high levels. Patients with diabetes mellitus, and with diabetic complications in particular, have a higher SSAO activity in plasma compared to healthy controls. It has therefore been speculated that high SSAO activity is involved in the development of vascular complications associated with diabetes. The aim of this thesis is to investigate the importance of SSAO in the development of disorders of a vascular origin. We have studied the transcriptional regulation of the SSAO gene, by inducing diabetes in NMRI and in transgenic mice, overexpressing the human form of SSAO in smooth muscle cells. We found that the increase in SSAO activity in diabetes is accompanied by reduced mRNA levels of the endogenous mouse gene, suggesting a negative feedback on the transcription of the SSAO gene. In addition, the transgenic mice exhibited an abnormal phenotype in the elastic tissue of aorta and renal artery. These mice have a lower mean artery pressure and an elevated pulse pressure. These results indicate that high SSAO activity in smooth muscle cells is associated with a change in the morphology of large arteries. This is likely contributing to the development of vascular complications in diabetes.
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sRAGE, S100 proteins and PTPN22 C1858T genetic polymorphism in rheumatoid arthritisYueh-Sheng Chen Unknown Date (has links)
Rheumatoid arthritis is a chronic inflammatory autoimmune disease. Measurement of the level of serum markers (sRAGE, S100A9, S100A8 and S100A12) and genetic testing for the presence of the PTPN22 genetic polymorphism could help elucidate the underlying cause of inflammation and complications in RA, such as atherosclerosis. Therefore, serum levels of sRAGE, S100A9, S100A8 and S100A12 were measured by ELISA in patients with established RA (n=138). The associations between the serum levels of these molecules; and inflammatory markers and RA complications were analysed by multiple linear regression modelling. Established RA patients (n=192) were investigated for the PTPN22 C1858T genetic polymorphism by PCR-RFLP. Multiple logistic regression modelling was used to examine the association between PTPN22 C1858T genetic polymorphism and inflammatory markers and RA complications. In RA patients, we found that serum levels of S100A9 were associated with the body mass index (BMI); and the presence of S100A8 and S100A12. The serum levels of S100A8 in RA patients were associated with the presence of anti-citrullinated peptide antibodies, rheumatoid factor and S100A9. The serum levels of S100A12 in RA patients were associated with the presence of anti-citrullinated peptide antibodies and S100A9; and a history of diabetes. Inflammatory markers and RA complications were not associated with the PTPN22 genetic polymorphism in established RA patients; serum level of triglyceride was the only variable associated with PTPN22 C1858T in multiple logistic regression analysis. Taken together, these data suggest that serum levels of sRAGE, S100A9 and S100A12 protein may be useful correlates of inflammation and autoantibody production in RA patients. Further studies are recommended to determine whether these markers predict clinical outcomes when measured at the onset of RA.
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Mécanismes cellulaires, moléculaires et épigénétiques impliqués dans les complications de l'insuffisance rénale chronique / Cellular, molecular and epigenetic mechanism implicated in complications of chronic kidney diseaseSallee, Marion 28 January 2014 (has links)
L'insuffisance rénale chronique (IRC) se caractérise par la diminution progressive et irréversible des fonctions renales. Elle s'accompagne d'une accumulation d'un ensemble de toxines responsable du syndrome urémique. Le syndrome urémique touche tous les organes, et de façon préoccupante le système cardiovasculaire. Il est associé à une dysfonction endothéliale, à la production d'un stress oxydant et d'une inflammation. L'objectif de cette thèse était d'identifier les mécanismes moléculaires responsables des complications du syndrome urémique. La première partie a tenté d'identifier des épissages alternatifs associés à l'IRC. Deux épissages alternatifs ont été identifiés. Cependant, le petit nombre d'épissages alternatifs trouvé au vue du nombre de gènes étudiés, nous permet de conclure que si l'IRC peut être responsable de l'apparition d'épissages alternatifs, ce phénomène n'est pas déterminant dans la régulation de l'expression des gènes responsable des complications de l'IRC. Dans la deuxième partie, nous avons montré par une étude clinique que le taux d'une toxine urémique, l'acide indole acétique (IAA), était associé à la mortalité et à la survenue d'événements cardio-vasculaires. In vitro, l'IAA induit un stress oxydant et un signal inflammatoire par l'induction de la cyclooxygénase 2 (COX-2). Une voie inflammatoire non génomique impliquant aryl hydrocarbon receptor (AhR), p38 MAPK et NF-κB est responsable de l'induction de la COX-2 endothéliale par l'IAA. Nos travaux ont identifié de nouvelles cibles thérapeutiques dont la modulation pourrait avoir un impact sur la mortalité cardiovasculaire des patients présentant une maladie rénale chronique. / Chronic kidney disease (CKD) is characterized by an irreversible decrease in kidney functions. Accumulation of uremic toxins is implicated in the uremic syndrome. Uremic syndrome affects all organs and particularly the cardiovascular system. The aim of this thesis was to identify and understand the molecular mechanisms implicated in the uremic syndrome.The first part attempted to ascertain the existence of alternative splice events associated with CKD. Two alternative splicing were identified. The small number of alternative splice events highlighted allows us to conclude that this phenomenon does not seem to be a key event in the modulation of gene expression during CKD.In the second part of this work, we demonstrated that the plasmatic concentration of an uremic toxin, Indole-3-acetic acid (IAA), is associated with all-cause mortality and major cardiovascular events. In vitro, we demonstrated that IAA induced endothelial cyclooxygenase-2 expression and endothelial oxidative stress production. IAA activated an endothelial Aryl hydrocarbon receptor/P38MAPK/NF-κB pathway. The activation of this inflammatory AHR dependant pathway could play a critical role in the increase of cardiovascular morbidity and mortality observed during CKD.Our work provides new therapeutic targets. The modulation of their activation could reduce cardiovascular mortality in patients with chronic kidney disease.
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Mécanismes et conséquences des altérations de la fonction vasculaire dans le diabète de type 2 associé au trait drépanocytaire / Mechanisms and consequences of alterations in vascular function in combined type 2 diabetes and sickle cell traitSkinner, Sarah 10 December 2018 (has links)
Le taux du diabète de type 2 (DT2) est en augmentation partout dans le monde, y compris dans les régions du monde où le trait drépanocytaire (TD) est très prévalent. Le TD, la forme hétérozygote de la drépanocytose, est généralement considéré comme bénin. Cependant, une dysfonction vasculaire plus importante a été récemment observée chez les patients DT2 porteurs du TD (DT2-TD) par rapport à des patients DT2 non-porteurs du TD. En outre, certaines études démontrent que le TD pourrait rendre le dépistage du DT2 plus complexe. De ce fait, les deux objectifs principaux de ma thèse étaient d’étudier les difficultés liées au dépistage et le suivi du DT2 chez les porteurs du TD, et d’évaluer les mécanismes et conséquences de la dysfonction vasculaire amplifiée chez les porteurs du TD. La 1ère étude a comparé deux mesures typiques (l’HbA1c et la glycémie à jeun) et une mesure atypique (fructosamine) de la glycémie chez des adultes sénégalais avec et sans le TD. Cette étude a démontré une disparité entre ces mesures qui étaient plus marquées chez des porteurs du TD. La 2ème étude a observé que les prévalences d’hypertension, de rétinopathie, et de néphropathie étaient plus élevées chez les sujets DT2-TD que chez les sujets diabétiques. La dysfonction vasculaire à l’origine de ces complications plus fréquentes semble impliquer les produits de glycation avancés. Les études 3 et 4 étaient réalisées dans un modèle murin du DT2-TD. L’étude 3 a montré une vasodilatation endothélium-dépendante significativement réduite chez des souris DT2-TD. Enfin, l’étude 4 a montré que la vasodilatation in-vivo induite par acétylcholine était augmentée chez la souris DT2-TD via un mécanisme dépendant de la cyclooxygenase-2. Ce travail de thèse a permis de mieux comprendre les difficultés liées au dépistage du DT2 chez les porteurs du TD, de montrer que le TD est un facteur de risque de complications vasculaire dans le DT2 et d’explorer les mécanismes à l’origine de cette dysfonction vasculaire plus marquée / Rates of type 2 diabetes (T2D) are rapidly increasing worldwide, including in regions, and among populations, of the globe where sickle cell trait (SCT) is prevalent. SCT, the heterozygote form of sickle cell disease, is generally considered a benign condition. However, evidence shows that vascular function is more severely impaired in people with combined T2D and SCT (T2D-SCT) than in those with T2D only. Furthermore, evidence suggests that SCT could complicate screening for T2D, thereby increasing the risk of delayed diagnosis of T2D. In light of this information, the main objectives of this thesis were to study the challenges related to diagnosing and monitoring T2D in individuals with SCT, and to evaluate the mechanisms and consequences of the amplified vascular dysfunction observed in T2D-SCT. Study 1 compared the agreement between two standard measures of glycemia, HbA1c and fasting glucose, and one alternative measure of glycemia, fructosamine, in Senegalese adults with and without SCT. The findings revealed substantial disparities between the markers of glycemia, and these differences were exaggerated in individuals with SCT. Study 2 illustrated that SCT could potentially augment the risk of developing retinopathy, nephropathy, and hypertension in T2D, and demonstrated that AGEs are likely implicated in the vascular dysfunction observed in T2D-SCT. Studies 3 and 4 studied microvascular function in a mouse model of T2D-SCT. Study 3 showed that T2D-SCT mice had significantly impaired endothelium-dependent vasodilation in-vivo. Study 4 revealed that ACH-mediated vasodilation in-vivo was significantly elevated in the microvasculature of mice with combined T2D and SCT due to cyclooxygenase-2 dependent mechanisms. Overall these findings deepen our understanding about the complexities related to diagnosing and managing T2D in individuals with SCT
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INCIDÊNCIA DE COMPLICAÇÕES VASCULARES EM TRANSPLANTE RENAL ENTRE 2013 E 2014 NA SANTA CASA DE MISERICÓRDIA DE GOIÂNIABezerra, Ana Paula da Silva Azevedo Nora 22 March 2016 (has links)
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Previous issue date: 2016-03-22 / Introduction: Even though kidney transplant represents a new perspective to
individuals with chronical kidney disease due to its correlation with a better quality of
life results and morbimortality indexes, the procedure itself is not free of risks.
Vascular complications rates around the world varies from 1 – 23% and it is are also
associated with a high risk of kidney graft losses. Objective: To evaluate the
incidence of vascular complications among patients submitted to kidney transplant at
Santa Casa de Misericórdia de Goiânia on a period of time between January 2013 to
December 2014. Material and Methods: It was analyzed 35 files from patients
submitted to kidney transplant at Santa Casa de Misericórdia de Goiânia on a period
of time between January 2013 and December 2014. It was analyzed the following
variables: renal artery stenosis, renal artery thrombosis, renal vein stenosis, renal
vein thrombosis, renal artery pseudoaneurysm, arteriovenous fistula, renal artery
kinking, kidney graft torsion and kidney infarction. It was also collected data for:
kidney graft side, donator´s aspects (alive or deceased), receptor´s age, receptor´s
gender, necessity for reintervention and cold ischemia time. Results: It was included
32 patients, 34,38% females and 65,62% males, with median age of 46 years old.
Among all surgical complications it was found 3 events of urinary leakage (9,3%), 2
events of retroperitoneal abscess (6,25%), 1 event of kidney graft torsion (3,12%)
and 1 event of arterial stenosis (3,12%). All kidney grafts came from deceased
donators (100%) and there were no graft losses. Conclusion: Even though the
following study had shown a low incidence of vascular complications related with
kidney transplant, the TIF more than 24 hours was the only independent risk factor
associated with this event. / Introdução: Embora o transplante renal represente uma perspectiva ao
indivíduo portador de doença renal crônica terminal por se correlacionar a melhores
índices de qualidade de vida e de morbimortalidade, este procedimento não é isento
de riscos. As taxas de complicações vasculares variam em todo mundo de 1 – 23%
e guardam importância por estar associadas a elevado risco de perda do enxerto.
Objetivo: Avaliar a incidência de complicação vascular em pacientes submetidos a
transplante renal na Santa Casa de Misericórdia de Goiânia no período entre janeiro
de 2013 a dezembro de 2014. Material e Métodos: Foram analisados 35 prontuários
de pacientes submetidos a transplante renal na Santa Casa de Misericórdia de
Goiânia no período de Janeiro de 2013 a Dezembro de 2014. Foram analisadas as
seguintes variáveis: estenose de artéria renal, trombose de artéria renal, estenose
de veia renal, trombose de veia renal, pseudoaneurisma de artéria renal, fístula
arteriovenosa, kinking de artéria renal, torção de enxerto e infarto. Foi coletado em
prontuário: rim transplantado, tipo de doador, idade do receptor, gênero do receptor,
reinternação, tempo de isquemia fria. Resultados: A população estudada incluiu 32
pacientes, sendo 34,38% do sexo feminino e 65,62% do sexo masculino, com média
de idade de 46 anos. Entre as complicações cirúrgicas, ocorreram 3 casos de fistula
urinária (9,3%), 2 casos de coleção (6,25%), 1 caso de torção de enxerto (3,12%) e
1 caso de estenose arterial (3,12%). Todos os enxertos (100%) foram de doador
falecido e não houve perda de enxerto em nenhum caso (0%). Conclusões: Embora
o presente estudo tenha observado uma baixa incidência de complicação vascular
relacionada a transplante renal, o TIF superior a 24hs foi o único fator de risco
independente associado a tal evento (p=0,034).
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Mοριακοί μηχανισμοί που ενέχονται στην παθογένεια των αγγειακών επιπλοκών στον σακχαρώδη διαβήτηΔεττοράκη, Αθηνά 13 November 2007 (has links)
Ο Σακχαρώδης Διαβήτης (ΣΔ) είναι μια μεταβολική διαταραχή, που χαρακτηρίζεται από χρόνια υπεργλυκαιμία ως αποτέλεσμα διαταραχής στην έκκριση της ινσουλίνης ή τη δράση της ή και στα δύο αυτά χαρακτηριστικά. Οι μακροπρόθεσμες επιπτώσεις της χρόνιας υπεργλυκαιμίας στον ΣΔ διακρίνονται σε μικροαγγειακές και μακροαγγειακές επιπλοκές. Η μικροαγγειακή νόσος οδηγεί σε αμφιβληστροειδοπάθεια, νεφρική ανεπάρκεια και νευροπάθεια, ενώ η σχετιζόμενη με τον ΣΔ μακροαγγειακή νόσος προκαλεί αυξημένο κίνδυνο για έμφραγμα μυοκαρδίου, αγγειακά εγκεφαλικά επεισόδια και ακρωτηριασμούς των άκρων.
Έχει βρεθεί ότι η υπεργλυκαιμία είναι η κύρια αιτία της μικροαγγειακής νόσου, ενώ στην παθογένεια της μακροαγγειακής νόσου συμμετέχει η υπεργλυκαιμία, αλλά και η αντίσταση στην ινσουλίνη. Ο σύνδεσμος ανάμεσα στην χρόνια υπεργλυκαιμία και την αγγειακή βλάβη έχει αποδοθεί σε τέσσερα ανεξάρτητα βιοχημικά μονοπάτια:
1. Αυξημένη δραστηριότητα του μονοπατιού της πολυόλης
2. Συσσώρευση τελικών προϊόντων προχωρημένης γλυκοζυλίωσης
(Advanced Glycation Endproducts: AGEs)
3. Ενεργοποίηση της πρωτεϊνικής κινάσης C (PKC) και
4. Αυξημένη δραστηριότητα του μονοπατιού της εξοζαμίνης.
Αυτά τα φαινομενικά μη σχετιζόμενα μεταξύ τους μοριακά μονοπάτια έχουν έναν υποκείμενο κοινό μηχανισμό : την υπερπαραγωγή ριζών υπεροξειδίου από τη μιτοχονδριακή αλυσίδα μεταφοράς ηλεκτρονίων. Οι μιτοχονδριακές ελεύθερες ρίζες οξυγόνου, μέσω ενεργοποίησης της πολυμεράσης της πολυ-ADP-ριβόζης, μερικώς αναστέλλουν το γλυκολυτικό ένζυμο αφυδρογονάση της 3-φωσφορικής γλυκεραλδεΰδης, με αποτέλεσμα τη συσσώρευση των γλυκολυτικών ενδιάμεσων προϊόντων, όπως της 3-φωσφορικής γλυκεραλδεΰδης και της 6-φωσφορικής φρουκτόζης, που αποτελούν υποστρώματα για τα τέσσερα παραπάνω βιοχημικά μονοπάτια.
Το αποτέλεσμα της αντίστασης στην ινσουλίνη, όσον αφορά τις μακροαγγειακές επιπλοκές, είναι η αυξημένη ροή των ελεύθερων λιπαρών οξέων από τα λιποκύτταρα προς τα αρτηριακά ενδοθηλιακά κύτταρα. Η αυξημένη οξείδωση των ελεύθερων λιπαρών οξέων στα μιτοχόνδρια και η μιτοχονδριακή υπερπαραγωγή ελευθέρων ριζών οξυγόνου οδηγούν στην ενίσχυση των τεσσάρων μοριακών μονοπατιών με τον ίδιο ακριβώς μηχανισμό που έχει περιγραφεί παραπάνω για την υπεργλυκαιμία. Στην αντίσταση στην ινσουλίνη έχει παρατηρηθεί, επίσης, η μερική αναστολή του μονοπατιού της κινάσης της 3-φωσφατιδυλινοσιτόλης, που τελικά προάγει την ενίσχυση των αθηρογόνων και την καταστολή των αντι-αθηρογόνων ιδιοτήτων της ινσουλίνης.
Ο κύριος στόχος αυτής της βιβλιογραφικής εργασίας είναι η περιγραφή των μονοπατιών που οδηγούν στη δημιουργία των, επαγόμενων από την υπεργλυκαιμία αλλά και την αντίσταση στην ινσουλίνη, διαβητικών αγγειακών επιπλοκών, καθώς και του κοινού μηχανισμού (παραγωγής ελευθέρων ριζών οξυγόνου) που βρίσκεται πίσω από αυτά τα μονοπάτια, παρέχοντας πλέον μια καινούρια βάση για μελλοντική έρευνα και ανακάλυψη φαρμάκων, προληπτικών και θεραπευτικών της διαβητικής αγγειοπάθειας. / Diabetes Mellitus is a metabolic disorder characterized by chronic hyperglycemia, due to decreased secretion of insulin and/ or decreased tissue sensitivity to insulin. The sequelae of chronic hyperglycemia in diabetes of all phenotypes are divided into microvascular and macrovascular complications. Microvascular disease causes blindness, renal failure, and neuropathy, and diabetes-accelerated macrovascular disease causes excessive risk for myocardial infarction, stroke, and lower limb amputation.
Strict glycemic control has been shown to reduce both microvascular and macrovascular complications of diabetes. However, in contrast to diabetic microvascular disease, it is believed that hyperglycemia is not the major determinant of diabetic macrovascular disease : a large part of cardiovascular disease risk is due to insulin resistance.
The link between chronic hyperglycemia and vascular damage has been established by four independent biochemical abnormalities : increased polyol pathway flux, increased formation of Advanced Glycation End-products (AGEs), activation of Protein Kinase C (PKC), and increased hexosamine pathway flux. These seemingly unrelated pathways have an underlying common denominator : overproduction of superoxide by the mitochondrial electron transport chain. Mitochondrial reactive oxygen species (ROS) partially inhibit the glycolytic enzymes glyceraldehyde-3-phosphate dehydrogenase, which diverts increased substrate flux from glycolysis to pathways of glucose overutilization.
As for insulin resistance, it causes increased free fatty acid flux from adipocytes into endothelial cells and increased free fatty acid oxidation in macrovascular endothelial cells, resulting in mitochondrial overproduction of ROS by exactly the same mechanism described above about hyperglycemia. Furthermore, metabolic insulin resistance is characterized by pathway-specific impairment in phosphatidylinositol 3-kinase-dependent signaling, which also causes endothelial dysfunction.
Preliminary experimental evidence in vivo suggests that these mechanisms leading to diabetic microvascular and macrovascular complications offer a novel basis for research and drug development, targeting to prevention and treatment of angiopathy in Diabetes Mellitus.
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