The benefits of tight glycemic control in critical illness: Sweeter than assumed?

Loose-control of diabetes mellitus with protamine zinc insulin in cats: 185 cases (2005-2015)

This study evaluated the outcome of cats with diabetes mellitus treated with a loose-control approach using protamine zinc insulin and identified factors that influence the likelihood of remission and survival in these cats. A total of 185 client-owned domestic cats were followed until death, lost to follow-up, or the end of the 11-year study. These cats were treated primarily basing insulin dose adjustments on clinical response. Patient records were used to examine factors suspected of influencing success of diabetes management. The remission probability was 56.2%. Survival time ranged from 0 to 3808 days with a median of 1488 days. Recent pre-diabetic corticosteroid use, lower mean blood glucose concentration during treatment, and lower mean insulin dose significantly increased the likelihood of remission. A low-carbohydrate diet, occurrence of remission, lack of diabetic ketoacidosis at diagnosis, lower mean blood glucose value during treatment, and lower blood glucose value at diagnosis were significantly associated with increased survival time.

Glycation abolishes the cardioprotective effects of albumin during ex vivo ischemia-reperfusion

Hyperglycemia-induced oxidative stress plays a key role in the onset/progression of cardiovascular diseases. For example, it can trigger formation of advanced glycation end (AGE) products with ischemia-reperfusion performed under hyperglycemic conditions. For this study, we hypothesized that albumin modified by glycation loses its unique cardioprotective properties in the setting of ischemia-reperfusion under high glucose conditions. Here, ex vivo rat heart perfusions were performed under simulated normo- and hyperglycemic conditions, that is Krebs-Henseleit buffer containing 11 mmol/L and 33 mmol/L glucose, respectively, ± normal or glycated albumin preparations. The perfusion protocol consisted of a 60 min stabilization step that was followed by 20 min of global ischemia and 60 min reperfusion. Additional experiments were completed to determine infarct sizes in response to 20 min regional ischemia and 120 min reperfusion. At the end of perfusions, heart tissues were isolated and evaluated for activation of the AGE pathway, oxidative stress, and apoptosis. Our data reveal that native bovine serum albumin treatment elicited cardioprotection (improved functional recovery, decreased infarct sizes) under high glucose conditions together with enhanced myocardial antioxidant capacity. However, such protective features are lost with glycation where hearts displayed increased infarct sizes and poor functional recovery versus native albumin treatments. Myocardial antioxidant capacity was also lowered together with activation of the intracellular AGE pathway. These data therefore show that although albumin acts as a cardioprotective agent during ischemia-reperfusion, it loses its cardioprotective and antioxidant properties when modified by glycation.

Glucose Levels in Patients With Acute Respiratory Failure Requiring Mechanical Ventilation

BACKGROUND

Recent studies suggest that patients with acute exacerbations of chronic obstructive pulmonary disease (COPD) frequently develop hyperglycemia, which has been linked to adverse outcomes.

METHODS

We retrospectively collected information about patient demographics, admission diagnosis, comorbidities, use of insulin, and glucose levels and related tests in 174 patients who required mechanical ventilation for acute respiratory failure.

RESULTS

These patients had a mean age of 57.8 ± 16.8 years, a mean Acute Physiology and Chronic Health Evaluation (APACHE II) score of 13.8 ± 6.1, and an overall mortality of 32.2%. The mean number of ventilator days was 7.5 ± 7.1. The mean highest glucose level was 239.3 ± 88.9 mg/dL in patients with COPD (n = 41) and 259.1 ± 131.7 mg/dL in patients without COPD (n =133). Patients with diabetes had higher glucose levels than patients without this diagnosis ( P < .05). Patients receiving corticosteroids did not have increased glucose levels ( P > .05). The mortality rate was higher in patients with glucose levels >140 mg/dL than in patients below 140 mg/dL (35.1% vs 10.5%, P < .05 unadjusted analysis).

CONCLUSION

In this study, hyperglycemia occurred in 89% of the patients with acute respiratory failure requiring mechanical ventilation. The most important risk factor for this was a premorbid diagnosis of diabetes.

Partial inhibition of the ubiquitin-proteasome system ameliorates cardiac dysfunction following ischemia-reperfusion in the presence of high glucose

Background

Acute hyperglycemia co-presenting with myocardial infarction (in diabetic and non-diabetic individuals) is often associated with a poor prognosis. Although acute hyperglycemia induces oxidative stress that can lead to dysregulation of the ubiquitin–proteasome system (UPS), it is unclear whether increased/decreased UPS is detrimental with ischemia–reperfusion under such conditions. As our earlier data implicated the UPS in cardiac damage, we hypothesized that its inhibition results in cardioprotection with ischemia–reperfusion performed under conditions that simulate acute hyperglycemia.

Methods

Ex vivo rat heart perfusions were performed with Krebs–Henseleit buffer containing 33 mM glucose vs. controls (11 mM glucose) for 60 min stabilization, followed by 20 min global ischemia and 60 min reperfusion ± 5 µM lactacystin and 10 µM MG-132, respectively. The UPS inhibitors were added during the first 20 min of the reperfusion phase and various cardiac functional parameters evaluated. In parallel experiments, infarct sizes were assessed following 20 min regional ischemia and 120 min reperfusion ± each of the respective UPS inhibitors (added during reperfusion). Heart tissues were collected and analyzed for markers of oxidative stress, UPS activation, inflammation and autophagy.

Results

The proteasome inhibitor doses and treatment duration here employed resulted in partial UPS inhibition during the reperfusion phase. Both lactacystin and MG-132 administration resulted in cardioprotection in our experimental system, with MG-132 showing a greater effect. The proteasome inhibitors also enhanced cardiac superoxide dismutase protein levels (SOD1, SOD2), attenuated pro-inflammatory effects and caused an upregulation of autophagic markers.

Conclusions

This study established that partial proteasome inhibition elicits cardioprotection in hearts exposed to ischemia–reperfusion with acute simulated hyperglycemia. These data reveal that protease inhibition triggered three major protective effects, i.e. (a) enhancing myocardial anti-oxidant defenses, (b) attenuating inflammation, and (c) increasing the autophagic response. Thus the UPS emerges as a unique therapeutic target for the treatment of ischemic heart disease under such conditions.