Beneficial effects of gliclazide modified release compared with glibenclamide on endothelial activation and low-grade inflammation in patients with type 2 diabetes.
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AIM: Endothelial dysfunction, oxidative stress and systemic inflammation play an important role in the enhanced cardiovascular risk in diabetes. Carotid intima-media thickness (IMT), a widely accepted marker of subclinical atherosclerosis, is known to be increased in patients with type 2 diabetes. The relationships between plasma markers of cardiac risk and carotid IMT are not well known. We therefore studied a group of patients with type 2 diabetes to evaluate the relationships between plasma markers of cardiac risk and carotid IMT. DESIGN AND PATIENTS: We measured carotid IMT and the levels of soluble endothelial adhesion molecules [sE-selectin, intercellular cell adhesion molecule-1 (sICAM-1) and vascular cell adhesion molecule-1 (sVCAM-1)], C-reactive protein (CRP) and 8-isoprostane in 40 patients with type 2 diabetes without clinical macrovascular complications (HbA1c<10%, duration of diabetes<12 years) and 25 healthy subjects. We then examined the correlations between these plasma markers, carotid IMT and various clinical and biochemical parameters. RESULTS: Diabetic patients had higher plasma sE-selectin (p=0.03), sICAM-1 (p=0.05), CRP (p=0.047) and 8-isoprostane (p=0.001) concentrations than control subjects. Mean IMT values were identical (0.63 +/- 0.02 mm) in diabetic (range, 0.40-0.92 mm) and healthy subjects (range, 0.45-0.85 mm). In diabetic patients, stepwise multivariate analysis showed that HbA1c and plasma glucose were independent predictors of sE-selectin (r2=0.19 and r2=0.17, p<0.01, respectively), whereas waist circumference and body mass index (BMI) were predictors of sICAM-1 (r2=0.27, p=0.001 and r2=0.22, p=0.002, respectively). Waist circumference was the only predictor of CRP (r2=0.2, p<0.01), and systolic blood pressure was the only predictor of 8-isoprostane (r2=0.19, p=0.006). In control subjects, similar analysis showed that plasma glucose and waist circumference were predictors of sE-selectin and sICAM-1, respectively (r2=0.2, p<0.05). CONCLUSIONS: These results indicate that some well-controlled type 2 diabetic patients free of clinical macrovascular complications have elevated plasma markers of cardiovascular risk without having increased IMT. The elevation of plasma markers of endothelial cell activation (sE-selectin and s-ICAM-1) or inflammation (CRP) and oxidative stress (8-isoprostane) in diabetics vs. controls is distinct from and cannot be explained simply by differences in the burden of atherosclerosis as assessed by carotid IMT.
Increasing evidence implicates oxidized low-density lipoprotein (LDL) and advanced glycation end products (AGE) in the atherogenesis associated with diabetes mellitus. In the present study, we examined the in vitro effects of gliclazide on LDL oxidation and monocyte adhesion to endothelial cells induced by oxidized LDL and glycated albumin. To assess the clinical relevance of our in vitro findings, we also measured the effect on monocyte adhesion of gliclazide administration to type 2 diabetic patients. Incubation of human monocytes and endothelial cells with increasing concentrations of gliclazide (0 to 10 microg/mL) and native LDL (100 microg/mL) induced a dose-dependent diminution of cell-mediated LDL oxidation. Pretreatment of endothelial cells with gliclazide (0 to 10 microg/mL) before addition of native LDL (100 microg/mL) or glycated albumin (100 microg/mL) resulted in a dose-dependent diminution of oxidized LDL- and glycated albumin-induced monocyte adhesion to endothelial cells. In type 2 diabetic patients, administration of gliclazide inhibits the increased adhesiveness of monocytes to levels similar to those observed in control subjects. These results indicate that gliclazide is an antioxidant and suggest a beneficial effect of this drug in the prevention of atherosclerosis associated with type 2 diabetes.
Acromegaly is a chronic, debilitating condition caused by excessive secretion of growth hormone (GH). In the majority of cases the condition results from benign pituitary adenomas or, rarely, from ectopic production of GH-releasing hormone. Regardless of the cause, excess GH results in physical disfigurement associated with arthropathy, diabetes, hypertension, cardiac dysfunction, obstructive sleep apnea and colonic neoplasia. The death rate for acromegalic patients is 2 to 3 times higher than that of the general population, but with appropriate reduction of GH hypersecretion it tends to shift into the normal range. Treatment is thus aimed at normalizing GH secretion; eradicating or stabilizing the pituitary tumour while preserving normal pituitary function, and managing the associated complications. The treatment modalities available to achieve these objectives include transsphenoidal surgery, pharmacotherapy and radiation, or various combinations of these. This review provides an update on our current understanding of the pathophysiology of GH hypersecretion in acromegaly, the newly defined diagnostic criteria and the end point for a cure for acromegaly, and on new developments in drug treatment with the advent of slow-release forms of somatostatin analogues and the longer-acting dopamine receptor agonists, as well as in the area of radiotherapy. Its main purpose is to guide any physician involved in the diagnosis and management of patients with acromegaly.
OBJECTIVE: To examine the kinetic of human monocyte adhesion to endothelial cells stimulated by glycated albumin, the contributive role of cell adhesion molecules to this effect, and the effect of gliclazide--an hypoglycemic drug with antioxidant properties--on these parameters. METHODS: In-vitro experiments performed in the presence and absence of gliclazide consisted of: (1) time-dependent determination of human monocyte adhesion to human endothelial cells (ECs) pre-exposed to glycated albumin; (2) evaluation of adhesion after incubation of ECs with antibodies against cell surface adhesion molecules; and (3) determination of EC surface adhesion molecules and of the activity of the transcription factor NF-kappaB. RESULTS: Exposition of human ECs for 1-48 h to 100 microg/ml glycated albumin led to a time-dependent increase in human monocyte adhesion to endothelium. Pretreatment of ECs with 10 microg/ml gliclazide significantly decreased the glycated albumin-stimulated monocyte adhesion to these cells. Anti-antibodies against E-selectin (ELAM-1), vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) also reduced the stimulatory effect of glycated albumin on monocyte adhesion. In glycated albumin-treated ECs, an induction of both soluble and cell associated expression of ELAM-1, VCAM-1 and ICAM-1, an augmentation in the levels of these molecule transcripts and an increase in the DNA binding activity for NF-kappaB in the promoters of these antigens were observed. Gliclazide markedly inhibited the induction of all these parameters. CONCLUSIONS: Glycated albumin stimulates human monocyte adhesion to ECs by inducing cell associated ELAM-1, ICAM-1 and VCAM-1. Gliclazide effectively inhibits monocyte adhesion to ECs by reducing glycated albumin induction of EC adhesion molecules and NF-kappaB activation. These results suggest that gliclazide may be beneficial in the prevention of endothelial disturbances associated with hyperglycemia in diabetic patients.
GH deficiency (GHD) is associated with increased prevalence of atherosclerosis and cardiovascular morbidity. Because monocytes play a crucial role in the development of atherosclerosis, we investigated in the present study the effect of GH deficiency and subsequent GH replacement on monocytic function in hypopituitary subjects. Twelve patients were randomized to receive GH replacement therapy (either 3 or 6 microg/kg x day, s.c.) for 3 months. Plasma levels and monocyte production of cytokines and monocyte adhesion to endothelium were determined in controls and patients with GHD before and after GH treatment. Before GH therapy, patients with GHD had increased basal plasma tumor necrosis factor-alpha (TNF alpha; 220% over control values; P = 0.004) and interleukin-6 (IL-6; 340% over control values; P 0.0009) levels. Basal monocyte production of both cytokines was also significantly higher in patients with GHD [484% over control values for TNF alpha (P = 0.0007); 1479% over control values for IL-6 (P = 0.035)]. GH treatment for 3 months led to a reduction in plasma TNF alpha (135% over control values; P = 0.03, pre- vs. post-GH therapy), monocyte TNF alpha production (204% over control values; P = 0.01), plasma IL-6 (219% over control values; P = 0.07), and monocyte IL-6 production (448% over control values; P = 0.01). Plasma TNF alpha levels positively correlated with monocyte TNF alpha production in patients with GHD both before and after GH therapy (P = 0.003 and P = 0.049, respectively). A positive correlation (P = 0.0003) was also observed between monocyte TNF alpha production and monocyte IL-6 production. There were no correlations between these plasma cytokine levels or monocyte cytokine production and parameters of body composition, lipid profile, or IGF-I and IGF-binding protein-3 levels. Before GH treatment, adhesiveness of monocytes to cultured aortic endothelial cells was also enhanced. This alteration was not reversed by GH administration. In conclusion, our results demonstrate that markers of monocyte activation are increased in patients with GHD and that GH replacement partly reduces these abnormalities. Reduction of cellular activation of monocytes by GH therapy could potentially contribute to reduce the risk of cardiovascular events in patients with GHD.
OBJECTIVE: To evaluate the effect of gliclazide administration to NIDDM patients on 1) monocyte adhesion to cultured endothelial cells, 2) plasma cytokine and lipid peroxide levels, and 3) monocyte cytokine production. RESEARCH DESIGN AND METHODS: Poorly controlled glyburide-treated diabetic patients (n = 8) and healthy control subjects (n = 8) were recruited. At the beginning of the study, glyburide was replaced by an equivalent hypoglycemic dose of gliclazide. Serum and monocytes were isolated from blood obtained from control and diabetic subjects before and after 3 months of treatment with gliclazide. RESULTS: Plasma lipid peroxide levels and monocyte adhesion to endothelial cells are enhanced in NIDDM patients, and gliclazide administration totally reverses these abnormalities. Before gliclazide treatment, serum levels of cytokines did not differ in the control and the diabetic groups, with the exception of an enhancement of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL)-6 in NIDDM subjects. Basal and lipopolysaccharide (LPS)-stimulated monocyte production of interleukin-1 beta, IL-6, and IL-8 did not differ between the two groups. Furthermore, basal monocyte production of TNF-alpha was similar in the control and the diabetic groups, whereas a marked increase in the LPS-stimulated monocyte production of TNF-alpha was observed in the NIDDM group. Gliclazide treatment lowered LPS-stimulated TNF-alpha production by diabetic monocytes to levels similar to those observed in control subjects. CONCLUSIONS: Gliclazide administration to NIDDM patients inhibits the increased adhesiveness of diabetic monocytes to endothelial cells and reduces the production of TNF-alpha by these cells. These results suggest that treatment of NIDDM subjects with gliclazide may be beneficial in the prevention of atherosclerosis associated with NIDDM.
Low-density lipoprotein (LDL) oxidation has been suggested to play a key role in the pathogenesis of atherosclerosis, a major complication of diabetes mellitus. Gliclazide, a second-generation sulfonylurea, is widely used in the treatment of type II diabetes mellitus. Recently, a free-radical-scavenging activity of gliclazide has been reported. In the present study, we examined the effects of gliclazide on cell-mediated LDL oxidation and monocyte adhesion to endothelial cells induced by oxidatively modified LDL. Incubation of human monocytes and bovine aortic endothelial cells (BAE cells) with increasing concentrations of gliclazide (0 to 10 micrograms/mL) and native LDL (100 micrograms/mL) resulted in a dose-dependent diminution of cell-mediated LDL oxidation as assayed by measurement of thiobarbituric acid (TBA)-reactive substances (TBARS). In addition, exposure of BAE cells to gliclazide (0 to 10 micrograms/mL) and native LDL (100 micrograms/mL) induced a dose-dependent diminution of the oxidized LDL-induced monocyte adhesion to BAE cells as measured by the myeloperoxidase (MPO) assay. The effects of glyburide, another second-generation sulfonylurea, were also tested on cell-mediated oxidation of LDL and LDL-induced monocyte adhesion to the endothelium. No significant effect of this drug was observed on these two processes. These results therefore demonstrate that gliclazide is effective in vitro in reducing both cell-mediated LDL oxidation and monocyte adhesion to the endothelium. These findings suggest a potential beneficial effect of gliclazide in the prevention of atherosclerosis in diabetic patients.
OBJECTIVE: Hyperactivity of the HPA axis is a possible mechanism underlying abdominal obesity. We aimed to evaluate in premenopausal women with abdominal obesity, (i) the hypothalamic-pituitary-adrenal (HPA) axis responses to direct pituitary stimulation with corticotrophin releasing hormone (CRH) and to opioid blockade with naloxone, and (ii) the interaction between short-term serotoninergic activation with dexfenfluramine (dF), a serotonin-release agonist, and these responses. DESIGN AND SUBJECTS: Eight obese women (mean BMI, 35 kg/m2) with waist to hip ratio (WHR) > 0.85 were tested with CRH (1 microgram/kg i.v.) and naloxone (125 micrograms/kg i.v.) before and at the end of two treatment periods with dF (15 mg twice daily for 7 days) and placebo (washout 7 days) in a cross-over design. Eight normal weight control women were tested with CRH and naloxone. RESULTS: Prior to treatment, ACTH and cortisol responses to naloxone (areas under the curve) were significantly higher in obese women then in control women (P = 0.027 and P = 0.035 respectively) dF treatment resulted in significant (P < 0.05) reduction of ACTH and cortisol increments. In contrast, ACTH and cortisol responses to CRH were not significantly different in obese and control subjects and were unaffected by dF treatment. CONCLUSION: We conclude that women with abdominal obesity have hyperreactivity of the HPA axis to opiod blockage and that dexfenfluramine treatment reduces this hyperactivity.
BACKGROUND: Transsphenoidal adenomectomy is an effective treatment fo r microprolactinomas. However, postoperative recurrence of hyperprolactinemia is not rare. This study was designed to evaluate the long-term outcome of women with microprolactinomas operated on by transsphenoidal approach. METHODS: We retrospectively studied 64 women with microprolactinomas who underwent transsphenoidal adenomectomy and were followed for 10 to 20 years. RESULTS: Postoperatively, 58 women (90%) had normal plasma prolactin concentrations (<20 microg/L). After a mean of 3.3 years, during which the women were asymptomatic with normoprolactinemia, 25 (43%) had a relapse of hyperprolactinemia (> or = 20 microg/L). However, their evolution varied. Fifteen women had symptomatic hyperprolactinemia. Computed tomography (CT) scans showed recurrent microadenomas in 2 women. The other 10 women had only hyperprolactinemia. Of these women, 5 had transient hyperprolactinemia (29 +/- 4 microg/L) for 5 years, after which prolactin declined to normal 13 +/- 3 microg/L). The remaining five patients had elevated prolactin (31 +/- 3 microg/L) throughout the follow-up period (10 to 20 years). CT scan did not show recurrent adenomas in these women. Thirty-three women remained normoprolactinemic and asymptomatic for a mean period of 12 years (range, 10 to 20 years). CONCLUSIONS: In conclusion, most of the patients with late relapse of hyperprolactinemia have slight functional hyperprolactinemia and remain asymptomatic with no evidence of tumor recurrence.
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Transsphenoidal selective adenomectomy is the most efficient primary treatment for acromegaly. However, management of persistent or recurrent disease remains controversial. The objective of the present study was to evaluate the early and long-term efficacy and safety of a second transsphenoidal surgery performed in those cases. The results of a retrospective study of 16 patients undergoing reoperation by the senior author (J.H.) between 1970 and 1991 are reported. Reoperation was performed for persistent or progressive acromegaly in 11 patients, visual impairment in four, and disease recurrence in one. Normalization of growth hormone (GH) was defined as a basal GH level of less than 5 micrograms/L and suppression to less than 2 micrograms/L during the oral glucose tolerance test. Long-term follow-up data were available in 15 patients. The second transsphenoidal surgery induced a greater than 50% decrease of GH level in 11 patients. Three (19%) of 16 patients were cured according to the authors' criteria and remained so after 2, 7, and 20 years. Two more patients had a postoperative basal GH level of less than 5 micrograms/L but incomplete suppression during the oral glucose tolerance test. Thus, a total of five patients (31%) achieved a basal GH of less than 5 micrograms/L. One other patient who had no initial improvement after the second transphenoidal surgery had spontaneous normalization of his GH level after 13 years. The following complications of the second surgery occurred in three patients: one subarachnoid hemorrhage, two new visual field defects, one cranial nerve palsy, and one meningitis. Moreover, 10 patients (62.5%) developed one or more new pituitary hormone deficiencies. In conclusion, reoperation for persistent or recurrent acromegaly has low success and high complication rates. According to the authors' experience, this procedure should be reserved for patients unresponsive to other forms of therapy or with progressive visual impairment despite medical therapy.
OBJECTIVE: To reach a Canadian consensus on the diagnosis and management of acromegaly. OPTIONS DIAGNOSIS: documenting autonomous growth-hormone hypersecretion and imaging of the pituitary. TREATMENT: surgical resection, adjunctive therapy with bromocriptine or octreotide and radiation therapy. OUTCOMES: Reduction of the morbidity and mortality associated with acromegaly. EVIDENCE: Review of international literature. VALUES: Achievement of consensus among a panel of Canadian endocrinologists. BENEFITS, HARMS AND COSTS: Acromegaly is a chronic debilitating condition that is associated with morbidity and mortality. This consensus statement is designed to improve the diagnosis and management of this rare condition in order to minimize the negative outcomes. Costs were not considered. RECOMMENDATIONS: The diagnosis of acromegaly is established by documenting autonomous growth-hormone hypersecretion and by imaging the pituitary. Surgical resection is the cornerstone of treatment; however, adjunctive therapy is often needed. Although growth-hormone reduction is often associated with alleviation of symptoms, an attempt should also be made to normalize levels of growth hormone and its target growth factor, insulin-like growth factor-I (IGF-I). Persistent secretion of excess growth hormone and IGF-I may pose significant long-term health risks. A suggested therapeutic algorithm is provided. The ease of administration of bromocriptine should prompt a trial of therapy with this agent. The subcutaneous use of octreotide is of particular benefit to those patients with persistently high levels of growth hormone and IGF-I that cannot be suppressed by other means. Because acromegaly is relatively rare and complex, its diagnosis and treatment require the concerted efforts of an endocrinologist, an neurosurgeon and a radiation oncologist.
Several growth factors have been implicated in the derangements of cellular metabolism and proliferation that occur in diabetes, eg. kidney mesangial expansion, retinal neovascular formation, and acceleration of atherosclerosis in large vessels. These phenomena contribute to the development and progression of diabetic microvascular and macrovascular disease. Pharmacological interventions aimed at reducing growth factor alterations, among other actions in diabetic vasculopathy, include a multitude of classes of drugs, such as angiotensin-converting enzyme (ACE) inhibitors, calcium antagonists, lipid-lowering drugs, and somatostatin analogs. New potential interventions, ie, antisense oligonucleotide local delivery, are being applied in growth factor research and may prove beneficial in diabetic macrovascular disease.
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The purpose of this study was to determine the effects of dexfenfluramine on body weight and post-prandial thermogenesis in obese subjects. Thirty obese subjects, men and women, with an excess weight between 20 and 80% of the ideal weight and aged from 20 to 60 years, participated in this double-blind, placebo-controlled study. During the treatment period, the subjects were not submitted to caloric restriction. Basal metabolic rate and postprandial thermogenesis (following a 400 kcal test meal) measurements were made by indirect calorimetry. Metabolic parameters such as glucose, insulin, thyroid hormones, free fatty acids, beta-hydroxybutyrate, total cholesterol and triglycerides were also measured before the test meal. These measurements were done at baseline, after one week and after three months of treatment. Following the three month treatment period, the mean weight loss of the dexfenfluramine group was 4.6 +/- 1.6 kg (s.e.) (P < 0.01) whereas the placebo group maintained the initial weight. The mean weight loss in the dexfenfluramine group represented 15% of the initial overweight. There was no significant change in either group in basal metabolic rate and postprandial thermogenesis following one week and three months of treatment (P > 0.05). The caloric intake after the treatment period was significantly reduced in the dexfenfluramine group (from 1631 +/- 103 kcal (s.e.) to 1353 +/- 109 kcal (s.e.); P < 0.05); in the placebo group, the changes were not significant (P > 0.05). The plasma concentrations of tri-iodothyronine, total cholesterol and triglycerides were significantly reduced in the dexfenfluramine group (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)