Adam Kruger

D-4F Induces Heme Oxygenase-1 and Extracellular Superoxide Dismutase, Decreases Endothelial Cell Sloughing, and Improves Vascular Reactivity in Rat Model of Diabetes

Background—Apolipoprotein A1 mimetic peptide, synthesized from D-amino acid (D-4F), enhances the ability of HDL to protect LDL against oxidation in atherosclerotic animals. Methods and Results—We investigated the mechanisms by which D-4F provides antioxidant effects in a diabetic model. Sprague-Dawley rats developed diabetes with administration of streptozotocin (STZ). We examined the effects of daily D-4F (100 &mgr;g/100 g of body weight, intraperitoneal injection) on superoxide (O2−), extracellular superoxide dismutase (EC-SOD), vascular heme oxygenase (HO-1 and HO-2) levels, and circulating endothelial cells in diabetic rats. In response to D-4F, both the quantity and activity of HO-1 were increased. O2− levels were elevated in diabetic rats (74.8±8×103 cpm/10 mg protein) compared with controls (38.1±8×103 cpm/10 mg protein; P<0.01). D-4F decreased O2− levels to 13.23±1×103 (P<0.05 compared with untreated diabetics). The average number of circulating endothelial cells was higher in diabetics (50±6 cells/mL) than in controls (5±1 cells/mL) and was significantly decreased in diabetics treated with D-4F (20±3 cells/mL; P<0.005). D-4F also decreased endothelial cell fragmentation in diabetic rats. The impaired relaxation typical of blood vessels in diabetic rats was prevented by administration of D-4F (85.0±2.0% relaxation). Western blot analysis showed decreased EC-SOD in the diabetic rats, whereas D-4F restored the EC-SOD level. Conclusions—We conclude that an increase in circulating endothelial cell sloughing, superoxide anion, and vasoconstriction in diabetic rats can be prevented by administration of D-4F, which is associated with an increase in 2 antioxidant proteins, HO-1 and EC-SOD.

L-4F treatment reduces adiposity, increases adiponectin levels, and improves insulin sensitivity in obese mice

We hypothesized that the apolipoprotein mimetic peptide L-4F, which induces arterial anti-oxidative enzymes and is vasoprotective in a rat model of diabetes, would ameliorate insulin resistance and diabetes in obese mice. L-4F (2 mg/kg/d) administered to ob/ob mice for 6 weeks limited weight gain without altering food intake, decreased visceral (P < 0.02) and subcutaneous (P < 0.045) fat content, decreased plasma IL-1β and IL-6 levels (P < 0.05) and increased insulin sensitivity, resulting in decreased glucose (P < 0.001) and insulin (P < 0.036) levels. In addition, L-4F treatment increased aortic and bone marrow heme oxygenase (HO) activity and decreased aortic and bone marrow superoxide production (P < 0.001). L-4F treatment increased serum adiponectin levels (P < 0.037) and decreased adipogenesis in mouse bone marrow (P < 0.039) and in cultures of human bone marrow-derived mesenchymal stem cells (P < 0.022). This was manifested by reduced adiposity, improved insulin sensitivity, improved glucose tolerance, increased plasma adiponectin levels, and reduced IL-1β and IL-6 levels in obese mice. This study highlights the existence of a temporal relationship between HO-1 and adiponectin that is positively affected by L-4F in the ob/ob mouse model of diabetes, resulting in the amelioration of the deleterious effects of diabetes.

Up-Regulation of Heme Oxygenase Provides Vascular Protection in an Animal Model of Diabetes through Its Antioxidant and Antiapoptotic Effects

Heme oxygenase (HO) plays a critical role in the regulation of cellular oxidative stress. The effects of the reactive oxygen species scavenger ebselen and the HO inducers cobalt protoporphyrin and stannous chloride (SnCl2) on HO protein levels and activity, indices of oxidative stress, and the progression of diabetes were examined in the Zucker rat model of type 2 diabetes. The onset of diabetes coincided with an increase in HO-1 protein levels and a paradoxical decrease in HO activity, which was restored by administration of ebselen. Up-regulation of HO-1 expressed in the early development of diabetes produced a decrease in oxidative/nitrosative stress as manifested by decreased levels of 3-nitrotyrosine, superoxide, and cellular heme content. This was accompanied by a decrease in endothelial cell sloughing and reduced blood pressure. Increased HO activity was also associated with a significant increase in the antiapoptotic signaling molecules Bcl-xl and phosphorylation of p38-mitogen-activated protein kinase but no significant increases in Bcl-2 or BAD proteins. In conclusion, 3-nitrotyrosine, cellular heme, and superoxide, promoters of vascular damage, are reduced by HO-1 induction, thereby preserving vascular integrity and protecting cardiac function involving an increase in antiapoptotic proteins.

Long-Term Treatment with the Apolipoprotein A1 Mimetic Peptide Increases Antioxidants and Vascular Repair in Type I Diabetic Rats

Apolipoprotein A1 mimetic peptide (D-4F), synthesized from D-amino acid, enhances the ability of high-density lipoprotein to protect low-density lipoprotein (LDL) against oxidation in atherosclerotic disease. Using a rat model of type I diabetes, we investigated whether chronic use of D-4F would lead to up-regulation of heme oxygenase (HO)-1, endothelial cell marker (CD31+), and thrombomodulin (TM) expression and increase the number of endothelial progenitor cells (EPCs). Sprague-Dawley rats were rendered diabetic with streptozotocin (STZ) and either D-4F or vehicle was administered, by i.p. injection, daily for 6 weeks (100 μg/100 g b.wt.). HO activity was measured in liver, kidney, heart, and aorta. After 6 weeks of D-4F treatment, HO activity significantly increased in the heart and aorta by 29 and 31% (p < 0.05 and p < 0.49), respectively. Long-term D-4F treatment also caused a significant increase in TM and CD31+ expression. D-4F administration increased antioxidant capacity, as reflected by the decrease in oxidized protein and oxidized LDL, and enhanced EPC function and/or repair, as evidenced by the increase in EPC endothelial nitric-oxide synthase (eNOS) and prevention of vascular TM and CD31+ loss. In conclusion, HO-1 and eNOS are relevant targets for D-4F and may contribute to the D-4F-mediated increase in TM and CD31+, the antioxidant and anti-inflammatory properties, and confers robust vascular protection in this animal model of type 1 diabetes.

Effect of Beta Blockers, Angiotensin-Converting Enzyme Inhibitors or Angiotensin Receptor Blockers, and Statins on Mortality in Patients With Implantable Cardioverter-Defibrillators

Nine hundred sixty-five patients (mean age 70 years) with implantable cardioverter-defibrillator were followed for 32 +/- 33 months for all-cause mortality. Death occurred in 73 of 515 patients (13%) treated with beta blockers (group 1), in 84 of 494 patients (17%) treated with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers (group 2), in 56 of 402 patients (14%) treated with statins (group 3), in 40 of 227 patients (18%) treated with amiodarone (group 4), in 5 of 26 patients (19%) treated with sotalol (group 5), and in 64 of 265 patients (24%) treated with no beta blocker, angiotensin-converting enzyme inhibitor or angiotensin receptor blocker, statin, amiodarone, or sotalol (group 6) (p <0.001 for group 1 vs group 6 and group 3 vs group 6, p <0.02 for group 2 vs group 6). In conclusion, patients with implantable cardioverter-defibrillators should be treated with beta blockers, angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, and statins to reduce mortality.

Prevalence of appropriate cardioverter-defibrillator shocks in 1038 consecutive patients with implantable cardioverter-defibrillators.

During a 33-month follow-up of 1038 consecutive patients who had implantable cardioverter-defibrillators, appropriate shocks occurred in 329 of 1038 patients (32%). Appropriate shocks occurred in 101 of 380 patients (27%) treated with β-adrenergic blockers alone; in 31 of 95 patients (33%) treated with amiodarone alone; in 39 of 149 patients (26%) treated with β-blockers plus amiodarone; in 11 of 28 patients (39%) treated with sotalol alone; and in 147 of 386 patients (38%) treated with no β-blockers, amiodarone, or sotalol (P < 0.001 comparing patients treated with β-adrenergic blockers alone with patients treated with no β-blockers, amiodarone, or sotalol; and P < 0.01 comparing patients treated with β-blockers plus amiodarone with patients treated with no β-blockers, amiodarone, or sotalol). In conclusion, patients having implantable cardioverter-defibrillators should also be treated with β-adrenergic blockers to reduce the frequency of appropriate shocks.

Prevalence of complications during implantation and during 38-month follow-up of 1060 consecutive patients with implantable cardioverter-defibrillators.

During implantation and during 38-month follow-up of 1060 consecutive patients who had implantable cardioverter-defibrillators, complications occurred in 60 (5.7%) of 1060 patients. These complications consisted of fractured leads requiring lead revision in 36 (3.4%) patients, lead infection requiring antibiotics in 5 (0.5%) patients, device replacement because of malfunction in 5 (0.5%) patients, repositioning of leads in 3 (0.3%) patients, a hematoma at the time of implantation in 3 (0.3%) patients, pneumothorax at the time of implantation in 2 (0.2%) patients, repair of a defective generator in 1 (0.1%) patient, replacement of the device because of atrophy of the skin over the device in 1 (0.1%) patient, a transient ischemic attack because of atrial fibrillation developing during implantation in 1 (0.1%) patient, device replacement because of a recall from Guidant in 1 (0.1%) patient, pocket revision because of pain when lying on the side of the pacemaker in 1 (0.1%) patient, and pacemaker infection in 1 (0.1%) patient.