Beta-blockers after acute myocardial infarction in elderly patients with diabetes mellitus: time to reassess

Drugs Interfering with Insulin Resistance and Their Influence on the Associated Hypermetabolic State in Severe Burns: A Narrative Review

It has become widely accepted that insulin resistance and glucose hypermetabolism can be linked to acute pathologies, such as burn injury, severe trauma, or sepsis. Severe burns can determine a significant increase in catabolism, having an important effect on glucose metabolism and on muscle protein metabolism. It is imperative to acknowledge that these alterations can lead to increased mortality through organ failure, even when the patients survive the initial trauma caused by the burn. By limiting the peripheral use of glucose with consequent hyperglycemia, insulin resistance determines compensatory increased levels of insulin in plasma. However, the significant alterations in cellular metabolism lead to a lack of response to insulin's anabolic functions, as well as to a decrease in its cytoprotective role. In the end, via pathological insulin signaling associated with increased liver gluconeogenesis, elevated levels of glucose are detected in the blood. Several cellular mechanisms have been incriminated in the development of insulin resistance in burns. In this context, the main aim of this review article is to summarize some of the drugs that might interfere with insulin resistance in burns, taking into consideration that such an approach can significantly improve the prognosis of the burned patient.

Glucose Metabolism in Burns-What Happens?

Severe burns represent an important challenge for patients and medical teams. They lead to profound metabolic alterations, trigger a systemic inflammatory response, crush the immune defense, impair the function of the heart, lungs, kidneys, liver, etc. The metabolism is shifted towards a hypermetabolic state, and this situation might persist for years after the burn, having deleterious consequences for the patient's health. Severely burned patients lack energy substrates and react in order to produce and maintain augmented levels of glucose, which is the fuel "ready to use" by cells. In this paper, we discuss biological substances that induce a hyperglycemic response, concur to insulin resistance, and determine cell disturbance after a severe burn. We also focus on the most effective agents that provide pharmacological modulations of the changes in glucose metabolism.

Akt2 deficiency promotes cardiac induction of Rab4a and myocardial β-adrenergic hypersensitivity

Patients with diabetes mellitus can develop cardiac dysfunction in the absence of underlying coronary artery disease or hypertension; a condition defined as diabetic cardiomyopathy. Mice lacking the intracellular protein kinase Akt2 develop a syndrome that is similar to diabetes mellitus type 2. Expression profiling of akt2(-/-) myocardium revealed that Rab4a, a GTPase involved in glucose transporter 4 translocation and β-adrenergic receptor (βAR) recycling to the plasma membrane, was significantly induced. We therefore hypothesized that Akt2 deficiency increases myocardial β-adrenergic sensitivity. Confirmatory analysis revealed up-regulation of Rab4a mRNA and protein in akt2(-/-) myocardium. In cultured cardiomyocyte experiments, Rab4a was induced by pharmacological inhibition of Akt as well as by specific knockdown of Akt2 with siRNA. Isolated akt2(-/-) hearts were hypersensitive to isoproterenol (ISO) but exhibited normal sensitivity to forskolin. Prolonged ISO treatment led to increased cardiac hypertrophy in akt2(-/-) mice compared to wild type mice. In addition, spontaneous hypertrophy was noted in aged akt2(-/-) hearts that was inhibited by treatment with the βAR blocker propranolol. In agreement with previous results demonstrating increased fatty acid oxidation rates in akt2(-/-) myocardium, we found increased peroxisome proliferator-activated receptor α (PPARα) activity in the hearts of these animals. Interestingly, increased myocardial Rab4a expression was present in mice with cardiac-specific overexpression of PPARα and was also observed upon stimulation of PPARα activity in cultured cardiomyocytes. Accordingly, propranolol attenuated the development of cardiac hypertrophy in the PPARα transgenic mice as well. Our results indicate that reduced Akt2 leads to up-regulation of Rab4a expression in cardiomyocytes in a cell-autonomous fashion that may involve activation of PPARα. This maladaptive response is associated with hypersensitivity of akt2(-/-) myocardium to β-adrenergic stimulation.

Fatigue and physical activity in older women after myocardial infarction

BACKGROUND

Within 6 years of a myocardial infarction (MI) more women (35%) than men (18%) will have another MI. Participation in physical activity is one of the most effective methods to reduce cardiac risks; however, few older women participate. One of the most frequently reported barriers to physical activity is fatigue.

OBJECTIVES

The specific aims of this study were to (1) describe factors related to fatigue in older women after MI and (2) examine the relationship of fatigue to physical activity in older women after MI.

METHODS

This descriptive correlational study examined the effects of age, body mass index, comorbidities, sleep, beta-blocker medication, depression, and social support on fatigue and physical activity in women (N = 84), ages 65 to 88 years old, 6 to 12 months post-MI. All women had their height and weight measured and completed (1) a health form on comorbidities, physical activity, and medication history; (2) the Geriatric Depression Scale; (3) the Epworth Sleepiness Scale; (4) the Revised Piper Fatigue Scale; and (5) the Social Provisions Scale.

RESULTS

The majority (67%) of the women reported fatigue that they perceived as different from fatigue before their MI. Moderately strong correlations were noted among depression, sleep, and fatigue, and multivariate analysis indicated that depression and sleep significantly accounted for 32.7% of the variance in fatigue. Although only 61% of the women reported participating in physical activity for exercise, most were meeting minimal kilocalories per week for secondary prevention. Fatigue was not significantly associated with participation in physical activity.

CONCLUSION

Describing correlates to fatigue and older women's participation in physical activity after MI are important to develop interventions targeted at increasing women's participation in physical activity, thus decreasing their risk for recurrent MIs.

Intensification of therapeutic approaches reduces mortality in diabetic patients with acute myocardial infarction: the Munich registry

OBJECTIVE

The myocardial infarction (MI) registry of the Academic Schwabing Hospital, Munich, investigates the hospital course of diabetic and nondiabetic patients with acute MI. The aim of this study was to improve quality care management and to compare hospital mortality and therapeutic approaches (i.e., PTCA, stenting, GPIIb/IIIa receptor antagonists, glucose-insulin infusion).

RESEARCH DESIGN AND METHODS

Data of diabetic patients and nondiabetic patients were analyzed. All diabetic and nondiabetic subjects who were admitted in 1999 and 2001 were included: 1999, 126 (38%) diabetic and 204 (62%) nondiabetic patients; 2001, 91 (31%) diabetic and 205 (59%) nondiabetic patients.

RESULTS

In 1999, coronary angiography (P < 0.01), percutaneous transluminal coronary angioplasty (PTCA) (P < 0.001), and stenting (P < 0.001) were performed less frequently in diabetic than in nondiabetic patients. During this period, total hospital mortality (29 vs. 16%, P < 0.01) and mortality within 24 h after admission (14 vs. 5%, P = 0.01) were higher in diabetic than in nondiabetic patients. In 2001, frequencies of coronary angiography, PTCA, and stenting were increased in diabetic patients (P < 0.001 vs. 1999), and the interventions were comparable with those performed in nondiabetic patients. Furthermore, glucose-insulin infusion was administered in 46% of diabetic subjects. In 2001, total hospital mortality decreased to 17% in diabetic subjects (P = 0.028 vs. 1999) and mortality within 24 h after admission declined to 4% (P = 0.027 vs. 1999). Logistic regression analysis revealed that an increase in the number of therapeutic approaches (also when adjusted for clinical variables) is associated with a reduction in mortality of diabetic patients with acute MI (adjusted odds ratio 0.14, P < 0.0001).

CONCLUSIONS

Intensification of multiple advanced therapeutic strategies in diabetic patients with acute MI enables a substantial reduction in hospital mortality. The enforcement leads to rates of hospital mortality that are comparable to those of nondiabetic patients.