Burn injury decreases myocardial Na-K-ATPase activity: role of PKC inhibition

Acute kidney injury in patients with burns

Burn injury is associated with a high risk of acute kidney injury (AKI) with a prevalence of AKI among patients with burns of 9-50%. Despite an improvement in burn injury survival in the past decade, AKI in patients with burns is associated with an extremely poor short-term and long-term prognosis, with a mortality of >80% among those with severe AKI. Factors that contribute to the development of AKI in patients with burns include haemodynamic alterations, burn-induced systemic inflammation and apoptosis, haemolysis, rhabdomyolysis, smoke inhalation injury, drug nephrotoxicity and sepsis. Early and late AKI after burn injury differ in their aetiologies and outcomes. Sepsis is the main driver of late AKI in patients with burns and late AKI has been associated with higher mortality than early AKI. Prevention of early AKI involves correction of hypovolaemia and avoidance of nephrotoxic drugs (for example, hydroxocobalamin), whereas prevention of late AKI involves prevention and early recognition of sepsis as well as avoidance of nephrotoxins. Treatment of AKI in patients with burns remains supportive, including prevention of fluid overload, treatment of electrolyte disturbance and use of kidney replacement therapy when indicated.

Evaluation of selected antidiabetics in cardiovascular complications associated with cancer cachexia

So far, the cardio-protective potential of antidiabetics is proved, but their effect on cardiovascular complications associated with cancer cachexia is not explored until now. Insulin resistance and glucose intolerance along with systemic inflammation are prominent in cachexia but the potential effect of antidiabetic agents especially those belonging to biguanide, DPP4 inhibitors and SGLT2 on the heart are not studied till now. In present study, the effect of metformin, vildagliptin, teneligliptin, dapagliflozin and empagliflozin on cardiovascular complications associated with cancer cachexia by using B16F1 induced metastatic cancer cachexia and urethane-induced cancer cachexia was studied. These antidiabetic agents proved to be beneficial against cachexia-induced atrophy of the heart, preserved ventricular weights, maintained cardiac hypertrophic index, preserved the wasting of cardiac muscles assessed by HE staining, Masson trichrome staining, periodic acid Schiff staining and picro-Sirius red staining. Altered cardiac gene expression was attenuated after treatment with selected antidiabetics, thus preventing cardiac atrophy. Also, antidiabetic agents treatment improved the serum creatinine kinase MB, Sodium potassium ATPase and collagen in the heart. Reduction in blood pressure and heart rate was observed after treatment with antidiabetic agents. Results of our study show that the selected antidiabetics prove to be beneficial in attenuating the cardiac atrophy and helps in regulation of hemodynamic stauts in cancer cachexia-induced cardiovascular complications. Our study provides some direction towards use of selected antidiabetic agents in the management of cardiovascular complications associated with cancer cachexia and the study outcomes can be useful in desiging clinical trials.

Systemic study of selected histone deacetylase inhibitors in cardiac complications associated with cancer cachexia

Cancer cachexia is mainly characterized by wasting of skeletal muscles and fat and body weight loss, along with severe complications of major organs like liver, heart, brain and bone. There can be diminishing performance of these major organs as cancer cachexia progresses, one such drastic effect on the cardiac system. In the present study, differential effect of histone deacetylase inhibitors (HDACi) on cardiac complications associated with cancer cachexia is studied. Two models were used to induce cancer cachexia: B16F1 induced metastatic cancer cachexia and Lewis lung carcinoma cell - induced cancer cachexia. Potential of Class I HDACi entinostat, Class II HDACi MC1568, and nonspecific HDACi sodium butyrate on cardiac complications were evaluated using the cardiac hypertrophy markers, hemodynamic markers, and cardiac markers along with histopathological evaluation of heart sections by Periodic acid-Schiff staining, Masson's trichrome staining, Picro-sirius red staining, and haematoxylin and eosin staining. Immunohistochemistry evaluation by vimentin and caspase 3 protein expression was evaluated. Entinostat showed promising results by attenuating the cardiac complications, and MC1568 treatment further exacerbated the cardiac complications, while non-conclusive effect were recorded after treatment with sodium butyrate. This study will be helpful in evaluating other HDACi for potential in cardiac complications associated with cancer cachexia.

Inhibitory effect of Scutia buxifolia extracts, fractions, and ursolic acid on Na(+), K(+)-ATPase activity in vitro in membranes purified from rat hearts

ETHNOPHARMACOLOGICAL RELEVANCE

Scutia buxifolia is a tree native to South America and is used as a cardiotonic agent; however, this property has not been associated with a clear mechanism or a specific compound.

AIM OF THE STUDY

Given the importance of Na(+),K(+)-ATPase as a drug target in the treatment of heart failure, this study aimed to investigate the possible inhibitory effect of S. buxifolia crude extract and fractions (dichloromethane, ethyl acetate, and butanolic fractions), and identified compounds with effects on the activity of Na(+),K(+)-ATPase in vitro.

MATERIALS AND METHODS

First, we characterized the crude extract and fractions by high-performance liquid chromatography, and then monitored their effects on the activity of Na(+),K(+)-ATPase obtained from heart muscle and brain membranes of adult male Wistar rats.

RESULTS

We identified gallic acid, chlorogenic acid, caffeic acid, rutin, quercitrin, quercetin, and ursolic acid in S. buxifolia stem bark and leaves; quercitrin and ursolic acid were the main compounds in the ethyl acetate and dichloromethane fractions from leaves and stem bark. The crude extract (3 and 30mg/ml), and the ethyl acetate and dichloromethane fractions (0.1 and 1mg/ml) of both the stem bark and leaves inhibited Na(+),K(+)-ATPase activity in heart and brain samples. We found that, of the identified compounds, only ursolic acid (0.1mg/ml) was able to diminish Na(+), K(+)-ATPase activity in heart and brain samples.

CONCLUSIONS

These data indicated that the cardiotonic effects of S. buxifolia may be due to the inhibition of Na(+),K(+)-ATPase activity in heart muscle, supporting the popular use of this plant as a treatment for heart failure.

TNFα increases resting potential in isolated fibres from rat peroneus longus by a PKC mediated mechanism: involvement in ICU acquired polyneuromyopathy

BACKGROUND AND AIMS

Our aim was to investigate the effect of TNFα on muscle resting potential (RP) and then in muscle excitability and to demonstrate another mechanism implicated in intensive care units (ICU) acquired polyneuromyopathy.

METHODS

Experiments were carried out on adult female Wistar rats. After isolation of muscle fibres from peroneus longus, influence of TNFα was tested on RP by using intracellular microelectrodes. Digoxin and chelerythrin were used to determine the mechanism of TNFα action.

RESULTS

First, we found that TNFα induced a concentration dependent increase of muscle RP and that this mechanism, which was blocked by digoxin, was due to an effect on the Na/K ATPase. As it was also blocked by chelerythrin it was concluded that this effect was mediated by PKC activation of the Na/K ATPase.

CONCLUSIONS

We demonstrated that TNFα leads to a PKC mediated increase in muscle RP. Depolarization needed to reach the threshold voltage for muscle action potential should then be higher and this could be involved in the decrease in muscle excitability observed in acquired polyneuromyopathy.

Assessment of microcirculatory influence on cellular morphology in human burn wound healing using reflectance-mode-confocal microscopy

Previous studies have assessed the effects of changes in microcirculation on wound healing; however, the influence of microcirculation on tissue histomorphology remains widely unknown. Reflectance-mode-confocal microscopy (RMCM) enables in vivo tissue observation on a cellular level. We present RMCM data evaluating the local microcirculation and assess the influence on histomorphology during burn healing. RMCM was performed in 12 patients (aged; 36.2+/-14.2 years, maximum-burn-extent: 4% total body surface area) at times 12, 36, and 72 hours after a superficial burn. The following parameters were assessed: quantitative blood-cell-flow (cbf), epidermal thickness (Emin), basal-layer thickness (tbl), and granular cell-size (Agran). Cbf was found to be 54+/-3.6 cells/minutes (control), increased to 91+/-3.6 cells/minutes (p<0.05) 12 hours postburn; decreased to 71+/-6.1 cells/minutes (p<0.05) (36 hours), and to 63+/-2.3 cells/minutes (p>0.05) 72 hours postburn. Emin was 43.74+/-3.87 mum (control), increased to 51.67+/-4.04 mum (p<0.05) 12 hours, decreased to 48.67+/-3.51 mum (p<0.05) 36 hours, and to 45.33+/-3.21 mum (p>0.05) at 72 hours postburn. Tbl was 14.17+/-0.6 mum (control), increased to 16.93+/-1.15 mum (p<0.05) 12 hours, decreased to 15.93+/-1.20 mum (p<0.05) 32 hours, and to 15.00+/-0.85 mum (p>0.05) 72 hours postburn. Agran was 718+/-56.20 mum(2) (control), increased to 901+/-66.02 mum(2) (p<0.05) 12 hours, decreased to 826+/-56.86 mum(2) 36 hours, and 766+/-65.06 mum(2) at 72 hours postburn. RMCM enables in vivo observation of wound microcirculation and allows direct assessment of vascular effects on cutaneous histomorphology during the healing course of superficial burns.

Histometric and histomorphologic comparison of combustion and ambustion using in vivo reflectance-confocal microscopy

BACKGROUND

When combustion and ambustion induce a superficial injury, they are summarized as superficial burns, regardless of the underlying cause. Reflectance-confocal microscopy (RCM) allows noninvasive imaging of the human skin on morphological features. We hypothesized that combustion and ambustion have different histomorphological effects on the human skin.

METHODS

Superficial burns caused by combustion (CO-group, five females, three males; aged 26.8 +/- 14.2 years) and caused by ambustion (AM-group, four females, four males; aged 28.1 +/- 13.8 years) were evaluated 24 h after injury. The following parameters were obtained using RCM on injured and noninjured (control) site: horny layer thickness, epidermal thickness, granular cell size, basal layer thickness.

RESULTS

Compared with the controls (12.8 +/- 2.5 microm), horny layer thickness decreased significantly to 10.6 +/- 2.1 microm in the CO-group, whereas it increased significantly to 17.8 +/- 2.8 microm in the AM-group. The epidermal thickness did not differ significantly in CO-group (47.9 +/- 2.1 microm) and AM-group (49.0 +/- 3.1 microm), however, both increased significantly compared with the controls (42.7 +/- 1.6 microm). The basal layer thickness increased more in AM-group (17.0 +/- 1.2 microm) compared to CO-group (15.4 +/- 1.1 microm). Both differed significantly compared with their controls (13.9 +/- 0.9 microm). The granular cell size increased significantly in both groups compared to the controls (721 +/- 42 microm), however, a significantly higher increase was observed in CO-group compared to AM-group (871 +/- 55 microm vs. 831 +/- 51 microm).

CONCLUSIONS

RCM evaluates significant histomorphological differences in superficial burns caused by combustion and ambustion. The term "superficial burn" should consider the underlying cause and thus supplemented by the term "combustion" or "ambustion."