Effect of high glucose on protein kinase C phosphorylation in human neutrophils
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Diabetics suffer from unique microvascular and macrovascular complications thought to result from chronic hyperglycemia. Numerous studies examining the microbiological underpinnings for these complications have observed that the upregulation of PKC activity is prevalent in affected tissues and cells of diabetics; this upregulation has been implicated in the pathophysiology of the complications. Of the cells studied, little research has been directed towards neutrophils. This study looked for and examined the nature of the relationship between hyperglycemia and PKC in neutrophils. METHODS: Neutrophils were isolated from the blood samples of 13 diabetic and 13 matched healthy control subjects using a discontinuous Ficoll-Hypaque gradient system. Neutrophils were either lysed immediately or following incubation in a high-glucose medium or nonglucose medium for times of 15 min to 6 hrs. The whole cell lysate was separated by gel electrophoresis and transferred to a PVDF membrane and Western blot performed. PKC activity was qualitatively determined by measuring the density of bands (representing Phospho-PKC) on an x-ray film exposed to a chemiluminescence complex that included an antibody specific to the phosphorylated form of PKC[Beta]ll. RESULTS: Basal PKC activity was greater in diabetics than healthy controls and this activity displayed a higher correlation with Fasting Plasma Glucose than HbA[1C] (0.9379 vs. 0.7385, respectively). Incubating neutrophils in high-glucose medium (25mmol/L) increased PKC activity compared to basal activity and non-glucose medium incubation. This upregulation was observed to a similar degree in both diabetics and healthy controls and was maintained for up to 6 hrs of incubation without any significant deregulation. CONCLUSIONS: The activity of PKC[Beta]ll isoform in neutrophils of diabetics is increased and maintained chronically additionally, this effect is determined by hyperglycemia per se, independent of whether the subject is type l or 2 diabetic or non-diabetic.
Thesis (MSD)--Boston University, Goldman School of Dental Medicine, 2006 (Oral Biology and Periodontology).Includes bibliographical references: leaves 47-57.
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