ATP converts necrosis to apoptosis in oxidant-injured endothelial cells

Energy depletion by cell proliferation sensitizes the kidney epithelial cells to injury

Acute kidney injury activates both proliferative and antiproliferative pathways, the consequences of which are not fully elucidated. If an initial proliferation of the renal epithelium is necessary for the successful repair, the persistence of proliferation markers is associated with the occurrence of chronic kidney disease. We hypothesized that proliferation in stress conditions impacts cell viability and renal outcomes. We found that proliferation is associated with cell death after various stresses in kidney cells. In vitro, the ATP/ADP ratio oscillates reproducibly throughout the cell cycle, and cell proliferation is associated with a decreased intracellular ATP/ADP ratio. In vivo, transcriptomic data from transplanted kidneys revealed that proliferation was strongly associated with a decrease in the expression of the mitochondria-encoded genes of the oxidative phosphorylation pathway, but not of the nucleus-encoded ones. These observations suggest that mitochondrial function is a limiting factor for energy production in proliferative kidney cells after injury. The association of increased proliferation and decreased mitochondrial function was indeed associated with poor renal outcomes. In summary, proliferation is an energy-demanding process impairing the cellular ability to cope with an injury, highlighting proliferative repair and metabolic recovery as indispensable and interdependent features for successful kidney repair.NEW & NOTEWORTHY ATP depletion is a hallmark of acute kidney injury. Proliferation is instrumental to kidney repair. We show that ATP levels vary during the cell cycle and that proliferation sensitizes renal epithelial cells to superimposed injuries in vitro. More proliferation and less energy production by the mitochondria are associated with adverse outcomes in injured kidney allografts. This suggests that controlling the timing of kidney repair might be beneficial to mitigate the extent of acute kidney injury.

Smart Multifunctional UiO-66 Metal-Organic Framework Nanoparticles with Outstanding Drug-Loading/Release Potential for the Targeted Delivery of Quercetin

Herein, UiO-66 and its two functional analogs (with -NO₂ and -NH₂ functional groups) were synthesized, and their potential ability as pH stimulus nanocarriers of quercetin (QU), an anticancer agent, was studied. UiO-66 is a low-toxicity, biocompatible metal-organic framework with a large surface area and good stability, which can be prepared through a facile and inexpensive method. Before and after drug loading, various analyses were conducted to characterize the synthesized nanocarriers. Moreover, Monte Carlo simulations were performed to investigate their structures and interactions with quercetin. The most promising drug loading potential and prolonged drug release (over 25 days) were observed in QU@UiO-66-NO₂ with 37% drug loading content, which was the best-tested sample that exhibited a higher release rate under acidic conditions (pH = 5) than that in normal cells (pH = 7.4). This behavior is known as pH-stimulus-controlled ability. The cell treatment with free QU, UiO-66-R, and QU@UiO-66-R (R = -H, -NO₂, and -NH₂) was performed, and an MTT assay was conducted on HEK-293 and MDA-MB-231 cells for the cytotoxicity study. Additionally, the kinetic modeling of drug release was investigated on the basis of the analysis of the drug release profiles.

Cooling of Cells and Organs Confers Extensive DNA Strand Breaks Through Oxidative Stress and ATP Depletion

Cooling at 4°C is routinely used to lower metabolism and preserve cell and tissue integrity in laboratory and clinical settings, including organ transplantation. However, cooling and rewarming produce cell damage, attributed primarily to a burst of reactive oxygen species (ROS) upon rewarming. While DNA represents a highly vulnerable target of ROS, it is unknown whether cooling and/or rewarming produces DNA damage. Here, we show that cooling alone suffices to produce extensive DNA damage in cultured primary cells and cell lines, including double-strand breaks (DSBs), as shown by comet assay and pulsed-field gel electrophoresis. Cooling-induced DSB formation is time- and temperature-dependent and coincides with an excess production of ROS, rather than a decrease in ATP levels. Immunohistochemistry confirmed that DNA damage activates the DNA damage response marked by the formation of nuclear foci of proteins involved in DSB repair, γ-H2Ax, and 53BP1. Subsequent rewarming for 24 h fails to recover ATP levels and only marginally lowers DSB amounts and nuclear foci. Precluding ROS formation by dopamine and the hydroxychromanol, Sul-121, dose-dependently reduces DSBs. Finally, a standard clinical kidney transplant procedure, using cold static storage in UW preservation solution up to 24 h in porcine kidney, lowered ATP, increased ROS, and produced increasing amounts of DSBs with recruitment of 53BP1. Given that DNA repair is erroneous by nature, cooling-inflicted DNA damage may affect cell survival, proliferation, and genomic stability, significantly impacting cellular and organ function, with relevance in stem cell and transplantation procedures.

Modulation of adenine phosphoribosyltransferase-mediated salvage pathway to accelerate diabetic wound healing

Adenine phosphoribosyltransferase (APRT) is the key enzyme involved in purine salvage by the incorporation of adenine and phosphoribosyl pyrophosphate to provide adenylate nucleotides. To evaluate the role of APRT in the repair processes of cutaneous wounds in healthy skin and in diabetic patients, a diabetic mouse model (db/db) and age-matched wild-type mice were used. Moreover, the topical application of adenine was assessed. In vitro studies, analytical, histological, and immunohistochemical methods were used. Diabetic mice treated with adenine exhibited elevated ATP levels in organismic skin and accelerated wound healing. In vitro studies showed that APRT utilized adenine to rescue cellular ATP levels and proliferation from hydrogen peroxide-induced oxidative damage. HPLC-ESI-MS/MS-based analysis of total adenylate nucleotides in NIH-3T3 fibroblasts demonstrated that adenine addition enlarged the cellular adenylate pool, reduced the adenylate energy charge, and provided additional AMP for the further generation of ATP. These data indicate an upregulation of APRT in skin wounds, highlighting its role during the healing of diabetic wounds through regulation of the nucleotide pool after injury. Furthermore, topical adenine supplementation resulted in an enlargement of the adenylate pool needed for the generation of ATP, an important molecule for wound repair.

Antibiotic resistance genes attenuation in anaerobic microorganisms during iron uptake from zero valent iron: An iron-dependent form of homeostasis and roles as regulators

Zero valent iron (ZVI) has been previously documented to attenuate the propagation of antibiotic resistance genes (ARGs) in microbes, while how ZVI affects the evolution of ARGs remains unclear. Herein, we investigated the influences of ZVI on ARGs dissemination in anaerobic bioreactor treating oxytetracycline (tet) containing wastewater, by deciphering the roles of iron homeostasis and regulatory effects. A net reduction of tet gene targets ranging from 0.75 to 1.88 and 0.67 to 2.08 log unit in intracellular and extracellular DNA was achieved at the optimal dosage of 5 g/L ZVI, whereas 20 g/L ZVI made no effects on ARGs reduction. The reduced ARGs abundance by ZVI was directly related to the inhibited horizontal transfer of ARGs and decreased proliferation of resistant strains (mainly Paludibacter and WCHB1-32). The potential mechanisms included the increased antioxidant capacity, the depressed efflux pump system and the weakened energy driving force by Fur regulon in microbes (especially for Cloacibacterium and Dechloromonas). The negligible influence of 20 g/L ZVI on ARGs reduction was ascribed to the iron-catalyzed oxidative damage and reduced physiological activity. This study firstly illustrated the potential relationships among activation of iron uptake regulator leading to protection against oxidative stress, alternation of physiological metabolisms and reduction of ARGs dissemination. This work extents our understanding about the priority of ZVI in mitigating ARGs proliferation and sheds light on its potential application in wastewater treatment plants.

Chronic exposure to glyphosate induces transcriptional changes in honey bee larva: A toxicogenomic study

The honey bee Apis mellifera is the most abundant managed pollinator in diverse crops worldwide. Consequently, it is exposed to a plethora of environmental stressors, among which are the agrochemicals. In agroecosystems, the herbicide glyphosate (GLY) is one of the most applied. In laboratory assessments, GLY affects the honey bee larval development by delaying its moulting, among other negative effects. However, it is still unknown how GLY affects larval physiology when there are no observable signs of toxicity. We carried out a longitudinal experimental design using the in vitro rearing procedure. Larvae were fed with food containing or not a sub-lethal dose of GLY in chronic exposure (120 h). Individuals without observable signs of toxicity were sampled and their gene expression profile was analyzed with a transcriptomic approach to compare between treatments. Even though 29% of larvae were asymptomatic in the exposed group, they showed transcriptional changes in several genes after the GLY chronic intake. A total of 19 transcripts were found to be differentially expressed in the RNA-Seq experiment, mainly linked with defensive response and intermediary metabolism processes. Furthermore, the enriched functional categories in the transcriptome of the exposed asymptomatic larvae were linked with enzymes with catalytic and redox activity. Our results suggest an enhanced catabolism and oxidative metabolism in honey bee larvae as a consequence of the sub-lethal exposure to GLY, even in the absence of observable symptoms.

The combination of the glycolysis inhibitor 2-DG and sorafenib can be effective against sorafenib-tolerant persister cancer cells

Background

Chemotherapy remains a major clinical option for the successful treatment of cancer by eliminating fast-growing populations of cancer cells. However, drug resistance causes the failure of antitumor treatment. Increasing evidence suggests that a small subpopulation of cancer cells will enter a “persister state” under drug pressure. The persister cell pool constitutes a reservoir from which drug resistance may emerge. Therefore, targeting persister cells presents a therapeutic opportunity to prevent drug resistance and impede tumor relapse.

Materials and methods

RT-qPCR, Western blot, Seahorse, apoptosis assay, clonogenic assay, and xenografted mouse model were used for this study.

Results

We showed that a similar therapy-resistant cell state underlies the behavior of persister cells derived from sorafenib treatments with reversible, nonmutational mechanisms. Then, we demonstrated that persister cells showed upregulated glycolysis, as evidenced by higher ECAR, as well as increased glucose consumption and lactate production. A database analysis showed that sorafenib-tolerant persister cells exhibited the increased expression of the glycolytic enzyme hexokinase 2, which is closely related to the poor prognosis in liver cancer. We found that the combined treatment with the glycolytic inhibitor 2-DG and sorafenib increased persister cell apoptosis and inhibited colony formation. Consequently, we demonstrated that when persister cells were exposed to a low concentration of sorafenib, they suffered mitochondrial dysfunction but showed compensatory increases in glycolysis, which contributes to cell growth and proliferation. Finally, we showed that the combination of 2-DG and sorafenib reduced persister tumor growth in mice.

Conclusions

These findings suggest that such a combination can effectively hamper persister cell growth and may represent a promising therapeutic strategy to prevent persister cell resistance.

Low-level free nitrous acid efficiently inhibits the conjugative transfer of antibiotic resistance by altering intracellular ions and disabling transfer apparatus

Recently, the dissemination of antibiotic resistance genes (ARGs) via plasmid-mediated conjugation has been reported to be facilitated by a series of contaminants. This has highlighted potential challenges to the effective control of this principal mode of horizontal transfer. In the present study, we found that low levels (<0.02 mgN/L) of free nitrous acid (FNA) remarkably inhibited (over 90%) the conjugative transfer of plasmid RP4, a model broad-host-range plasmid, between Escherichia coli. The antimicrobial role of FNA at the applied dosages was firstly ruled out, since no dramatic reductions in viabilities of donor or recipient were observed. Instead, FNA appeared to reduce the available intracellular free Mg²⁺, which was confirmed to be triggered by the liberation of intracellular Fe²⁺. These alterations in intracellular Mg²⁺ and Fe²⁺ concentrations were found to significantly limit the available energy for conjugative transfer through suppression of glycolysis by decreasing the activities of glycogen phosphorylase and glyceraldehyde-3-phosphate dehydrogenase and also by diverting the glycolytic flux into the pentose phosphate pathway via activation of glucose-6-phosphate dehydrogenase towards the generation of NADPH rather than ATP. Moreover, RP4-encoding genes responsible for DNA transfer and replication (traI, traJ and trfAp), coupling (traG) and mating pair formation (traF and trbBp) were all significantly down-regulated after FNA treatment, indicating that the transfer apparatus required for plasmid processing and delivery was deactivated. By validating the inhibitory effects of FNA on conjugation in real wastewater, this study highlights a promising method for controlling the dissemination of ARGs in systems such as wastewater treatment plants.

Neuroprotective effects of the new Na channel blocker rs100642 in global ischemic brain injury

INTRODUCTION

RS100642, a mexiletine analogue, is a novel sodium channel blocker with neuroprotective and antioxidant activities. The protectivity of RS100642, which has been shown against focal cerebral ischemia, was investigated in global cerebral ischemia in this study.

MATERIAL AND METHODS

Global cerebral ischemia was induced for five minutes in adult male Wistar Albino rats via the 4-vessel occlusion method. Intravenous administration of 1 mg/kg RS100642 following reperfusion for 30 min (RS100642 group) was compared with a sham treatment group (ischemia group) and nonischemized group (control) histologically based on morphology and caspase-3 immunohistochemistry, and biochemically based both on measurement of oxidative stress including malondialdehyde (MDA) levels, superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) activities and on assessment of apoptosis including caspase-3 and -8 activities and tumor necrosis factor α (TNF-α) levels at the end of 6 h.

RESULTS

While the RS100642 group had significantly lower MDA levels and higher SOD activities than the sham treatment group (p < 0.05), GPx and CAT activities of the RS100642 and sham treatment groups were similar (p > 0.05) and significantly lower than those of the controls (p < 0.05). Necrosis and caspase-3 activity and immunoreactivity in the RS100642 group were significantly lower than those in the sham treatment group (p < 0.05), while there was no significant difference between groups regarding caspase-8 and TNF-α (p > 0.05).

CONCLUSIONS

Na⁺ channel blockade by RS100642 has remarkable neuroprotective effects following global brain ischemia/reperfusion damage. Further research is required to determine the optimum dose and time of administration.

The hidden nature of protein translational control by diphthamide: the secrets under the leather

The protein translation elongation factor eEF2 undergoes a unique posttranslational modification called diphthamidation. eEF2 is an essential factor in protein translation, and the diphthamide modification has been a famous target of the diphtheria toxin for a long time. On the other hand, the physiological function of this rare modification in vivo remains unknown. Recent studies have suggested that diphthamide has specific functions for the cellular stress response and active proliferation. In this review, we summarize the history and findings of diphthamide obtained to date and discuss the possibility of a specific function for diphthamide in regulating protein translation.

Oncolytic virus-induced cell death and immunity: a match made in heaven?

Our understanding of the mechanisms responsible for cancer development has increased enormously over the last decades. However, for many cancers, this has not been translated into a significant improvement in overall survival, and overall mortality remains high. Treatment for many malignancies remains based on surgery, chemotherapy, and radiotherapy. Significant progress has been made toward the development of more specific, more potent, and less invasive treatment modalities, but such targeted therapies remain the exception for most cancers. Thus, cancer therapies based on a different mechanism of action should be explored. The immune system plays an important role in keeping tumor growth at bay. However, in many cases, these responses are not strong enough to keep tumor growth under control. Thus, immunotherapy aims to boost the immune system to suppress tumor growth efficiently. This has been demonstrated by the recent successes of immune checkpoint therapy in several cancers. Oncolytic viruses (OVs) are another exciting class of immunotherapy agent. As well as replicating selectively within and killing tumor cells, OVs are able to elicit potent anti-tumor immune responses. Therapeutic vaccination with OVs, also referred to as cancer virotherapy, can thus be tailored to elicit vigorous cellular immune responses and even target individual malignancies in a personalized manner. In this review, we will describe the intricate link among oncolytic virotherapy, tumor immunology, and immunogenic cell death (ICD) and discuss ways to harness optimally their potential for future cancer therapy.

Protective effects of physical exercise on MDMA-induced cognitive and mitochondrial impairment

Debate continues about the effect of 3, 4-methylenedioxymethamphetamine (MDMA) on cognitive and mitochondrial function through the CNS. It has been shown that physical exercise has an important protective effect on cellular damage and death. Therefore, we investigated the effect of physical exercise on MDMA-induced impairments of spatial learning and memory as well as MDMA effects on brain mitochondrial function in rats. Male wistar rats underwent short-term (2 weeks) or long-term (4 weeks) treadmill exercise. After completion of exercise duration, acquisition and retention of spatial memory were evaluated by Morris water maze (MWM) test. Rats were intraperitoneally (I.P) injected with MDMA (5, 10, and 15mg/kg) 30min before the first training trial in 4 training days of MWM. Different parameters of brain mitochondrial function were measured including the level of ROS production, mitochondrial membrane potential (MMP), mitochondrial swelling, mitochondrial outermembrane damage, the amount of cytochrome c release from the mitochondria, and ADP/ATP ratio. MDMA damaged the spatial learning and memory in a dose-dependent manner. Brain mitochondria isolated from the rats treated with MDMA showed significant increase in ROS formation, collapse of MMP, mitochondrial swelling, and outer membrane damage, cytochrome c release from the mitochondria, and finally increased ADP/ATP ratio. This study also found that physical exercise significantly decreased the MDMA-induced impairments of spatial learning and memory and also mitochondrial dysfunction. The results indicated that MDMA-induced neurotoxicity leads to brain mitochondrial dysfunction and subsequent oxidative stress is followed by cognitive impairments. However, physical exercise could reduce these deleterious effects of MDMA through protective effects on brain mitochondrial function.

Alterations in Red Blood Cell Functionality Induced by an Indole Scaffold Containing a Y-Iminodiketo Moiety: Potential Antiproliferative Conditions

We have recently proposed a new erythrocyte-based model of study to predict the antiproliferative effects of selected heterocyclic scaffolds. Starting from the metabolic similarity between erythrocytes and cancer cells, we have demonstrated how the metabolic derangement induced by an indolone-based compound (DPIT) could be related to its antiproliferative effects. In order to prove the validity of our biochemical approach, in the present study the effects on erythrocyte functionality of its chemical precursor (PID), whose synthesis we reported, were investigated. The influence of the tested compound on band 3 protein (B3), oxidative state, ATP efflux, caspase 3, metabolism, intracellular pH, and Ca²⁺ homeostasis has been evaluated. PID crosses the membrane localizing into the cytosol, increases anion exchange, induces direct caspase activation, shifts the erythrocytes towards an oxidative state, and releases less ATP than in normal conditions. Analysis of phosphatidylserine externalization shows that PID slightly induces apoptosis. Our findings indicate that, due to its unique features, erythrocyte responses to exogenous molecular stimuli can be fruitfully correlated at structurally more complex cells, such as cancer cells. Overall, our work indicates that erythrocyte is a powerful study tool to elucidate the biochemical/biological effects of selected heterocycles opening considerable perspectives in the field of drug discovery.

ATP synthase subunit-β down-regulation aggravates diabetic nephropathy

In this study, we investigated the role of ATP synthase subunit-β (ATP5b) in diabetic nephropathy. Histopathological changes, fibrosis, and protein expressions of α-smooth muscle actin (α-SMA), advanced glycation end-products (AGEs), and ATP5b were obviously observed in the kidneys of db/db diabetic mice as compared with the control db/m(+) mice. The increased ATP5b expression was majorly observed in diabetic renal tubules and was notably observed to locate in cytoplasm of tubule cells, but no significant increase of ATP5b in diabetic glomeruli. AGEs significantly increased protein expression of ATP5b and fibrotic factors and decreased ATP content in cultured renal tubular cells via an AGEs-receptor for AGEs (RAGE) axis pathway. Oxidative stress was also induced in diabetic kidneys and AGEs-treated renal tubular cells. The increase of ATP5b and CTGF protein expression in AGEs-treated renal tubular cells was reversed by antioxidant N-acetylcysteine. ATP5b-siRNA transfection augmented the increased protein expression of α-SMA and CTGF and CTGF promoter activity in AGEs-treated renal tubular cells. The in vivo ATP5b-siRNA delivery significantly enhanced renal fibrosis and serum creatinine in db/db mice with ATP5b down-regulation. These findings suggest that increased ATP5b plays an important adaptive or protective role in decreasing the rate of AGEs-induced renal fibrosis during diabetic condition.

Inhibitor of caspase-activated DNase expression enhances caspase-activated DNase expression and inhibits oxidative stress-induced chromosome breaks at the mixed lineage leukaemia gene in nasopharyngeal carcinoma cells

BACKGROUND

Nasopharyngeal carcinoma (NPC) is commonly found in Asia, especially among the Chinese ethnic group. Chromosome rearrangements are common among NPC patients. Although the mechanism underlying the chromosome rearrangements in NPC is unclear, various mechanisms including activation of caspase-activated DNase (CAD) were proposed to contribute to chromosome rearrangements in leukaemia. Activation of CAD can be initiated by multiple agents, including oxidative stress, which is well implicated in carcinogenesis. CAD is the main enzyme that causes DNA fragmentation during apoptosis, and CAD is also implicated in promoting cell differentiation. In view of the role of oxidative stress in carcinogenesis and CAD activation, and since CAD was suggested to contribute to chromosome rearrangement in leukaemia, we hypothesise that oxidative stress-induced CAD activation could be one of the mechanisms that leads to chromosome rearrangements in NPC.

METHODS

SUNEI cells were treated with various concentrations of H2O2 for different period of time to ensure that cells undergo H2O2-induced MLL gene cleavage. Transfections with hCAD, mCAD, mutant hCAD, or cotransfection with hCAD and mICAD, and cotransfection with mutant hCAD and mICAD were performed. Gene expression was confirmed by Western blotting and MLL gene cleavage was assessed by inverse polymerase chain reaction (IPCR).

RESULTS

Treatment with H2O2 clearly induces cleavages within the MLL gene which locates at 11q23, a common deletion site in NPC. In order to investigate the role of CAD, CAD was overexpressed in SUNE1 cells, but that did not result in significant changes in H2O2-induced MLL gene cleavage. This could be because CAD requires ICAD for proper folding. Indeed, by overexpressing ICAD alone or co-expressing ICAD with CAD, Western blotting showed that CAD was expressed. In addition, ICAD overexpression also suppressed H2O2-induced MLL gene cleavage, suggesting a possible role of CAD in initiating chromosome cleavage during oxidative stress.

CONCLUSIONS

Oxidative stress mediated by H2O2 induces cleavage of the MLL gene, most likely via the caspase-activated DNase, CAD, and CAD expression requires ICAD. Since the MLL gene is located at 11q23, a common deletion site in NPC, thus stress-induced CAD activation may represent one of the mechanisms leading to chromosome rearrangement in NPC.

The metabolic cooperation between cells in solid cancer tumors

Cancer cells cooperate with stromal cells and use their environment to promote tumor growth. Energy production depends on nutrient availability and O₂ concentration. Well-oxygenated cells are highly proliferative and reorient the glucose metabolism towards biosynthesis, whereas glutamine oxidation replenishes the TCA cycle coupled with OXPHOS-ATP production. Glucose, glutamine and alanine transformations sustain nucleotide and fatty acid synthesis. In contrast, hypoxic cells slow down their proliferation, enhance glycolysis to produce ATP and reject lactate which is recycled as fuel by normoxic cells. Thus, glucose is spared for biosynthesis and/or for hypoxic cell function. Environmental cells, such as fibroblasts and adipocytes, serve as food donors for cancer cells, which reject waste products (CO₂ , H⁺, ammoniac, polyamines…) promoting EMT, invasion, angiogenesis and proliferation. This metabolic-coupling can be considered as a form of commensalism whereby non-malignant cells support the growth of cancer cells. Understanding these cellular cooperations within tumors may be a source of inspiration to develop new anti-cancer agents.

Effects of pretreatment hypothermia during resuscitated porcine hemorrhagic shock

OBJECTIVES

Accidental hypothermia increases mortality and morbidity after hemorrhage, but controversial data are available on the effects of therapeutic hypothermia. Therefore, we tested the hypothesis whether moderate pretreatment hypothermia would beneficially influence organ dysfunction during long-term, porcine hemorrhage and resuscitation.

DESIGN

Prospective, controlled, randomized study.

SETTING

University animal research laboratory.

SUBJECTS

Twenty domestic pigs of either gender.

INTERVENTIONS

Using an extracorporeal heat exchanger, anesthetized and instrumented animals were maintained at 38°C, 35°C, or 32°C core temperature and underwent 4 hours of hemorrhage (removal of 40% of the blood volume and subsequent blood removal/retransfusion to maintain mean arterial pressure at 30 mm Hg). Resuscitation comprised of hydroxyethyl starch and norepinephrine infusion titrated to maintain mean arterial pressure at preshock values.

MEASUREMENTS AND MAIN RESULTS

Before, immediately at the end of, and 12 and 22 hours after hemorrhage, we measured systemic and regional hemodynamics (portal vein, hepatic and right kidney artery ultrasound flow probes) and oxygen transport, and nitric oxide and cytokine production. Hemostasis was assessed by rotation thromboelastometry. Postmortem biopsies were analyzed for histomorphology (hematoxylin and eosin staining) and markers of apoptosis (kidney Bcl-xL and caspase-3 expression). Hypothermia at 32°C attenuated the shock-related lactic acidosis but caused metabolic acidosis, most likely resulting from reduced carbohydrate oxidation. Although hypothermia did not further aggravate shock-related coagulopathy, it caused a transitory attenuation of kidney and liver dysfunction, which was ultimately associated with reduced histological damage and more pronounced apoptosis.

CONCLUSIONS

During long-term porcine hemorrhage and resuscitation, moderate pretreatment hypothermia was associated with a transitory attenuation of organ dysfunction and less severe histological tissue damage despite more pronounced metabolic acidosis. This effect is possibly due to a switch from necrotic to apoptotic cell death, ultimately resulting from reduced tissue energy deprivation during the shock phase.

Antioxidant Enzymes and Lipid Peroxidation in Type 2 Diabetes Mellitus Patients with and without Nephropathy

BACKGROUND

Oxidative stress has been considered to be a pathogenic factor of diabetic complications including nephropathy. There are many controversies and limited studies regarding the antioxidant enzymes in diabetic nephropathy.

AIM

This study was to evaluate the levels of antioxidant enzymes and lipid peroxidation in Type-2 Diabetes Mellitus (DM) patients with and without nephropathy.

MATERIALS AND METHODS

The study included 90 age and sex matched subjects. Blood samples of all subjects were analyzed for all biochemical and oxidative stress parameters.

RESULTS

The malondialdehyde (MDA) levels and catalase (CAT) activity were significantly increased and reduced glutathione (GSH) levels and activities of glutathione peroxidase (GPx) and glutathione reductase (GR) were significantly decreased in Type-2 DM with and without nephropathy as compared to controls and also in Type-2 DM with nephropathy as compared to Type-2 DM without nephropathy. There were an excellent positive correlation of glycohemoglobin (HbA1c) with MDA and a good negative correlation of GPx with GSH in controls. There were positive correlations of GR, CAT, and superoxide dismutase (SOD) with MDA in Type-2 diabetes patients with nephropathy.

CONCLUSIONS

Intensity of oxidative stress in Type-2 diabetic patients with nephropathy is greater when compared with Type-2 diabetic patients without nephropathy as compared to the controls.

Proteomic characterization of the possible molecular targets of pyrrolizidine alkaloid isoline-induced hepatotoxicity

Pyrrolizidine alkaloids (PAs) are distributed in plants worldwide including medicinal herbs or teas. In the present study, we investigated the effects of isoline, which is a retronecine-type PA isolated from traditional Chinese medicinal herb Ligularia duciformis, on mouse liver proteins by using proteomic approaches. Firstly, our results showed that 110mg/kg isoline increased alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities in serum, and hepatic tissue pathological observation further confirmed isoline-induced liver injury. Proteomic analysis showed that the liver samples from mice of isoline group demonstrated about 13 differentially expressed proteins compared with normal group, and those proteins may be involved in isoline-induced liver injury in mice. Next, all these 13 protein spots were identified by MALDI-TOF-TOF MS or LTQ MS; and among them 9 differentially expressed proteins are involved in the process of oxidative stress or cellular energy metabolism. Further lipid peroxidation analysis and ATPase assay confirmed the existing of oxidative injury induced by isoline and consequent disruption of energy metabolism. Furthermore, an in silico drug target searching program INVDOCK identified 2 potential protein targets of isoline, and the results are in support of proteomic analysis. In summary, the possible signaling molecules related with isoline-induced liver injury were demonstrated in this study.

Toxicity of depleted uranium on isolated rat kidney mitochondria

BACKGROUND

Kidney is known as the most sensitive target organ for depleted uranium (DU) toxicity in comparison to other organs. Although the oxidative stress and mitochondrial damage induced by DU has been well investigated, the precise mechanism of DU-induced nephrotoxicity has not been thoroughly recognized yet.

METHODS

Kidney mitochondria were obtained using differential centrifugation from Wistar rats and mitochondrial toxicity endpoints were then determined in both in vivo and in vitro uranyl acetate (UA) exposure cases.

RESULTS

Single injection of UA (0, 0.5, 1 and 2mg/kg, i.p.) caused a significant increase in blood urea nitrogen and creatinine levels. Isolated mitochondria from the UA-treated rat kidney showed a marked elevation in oxidative stress accompanied by mitochondrial membrane potential (MMP) collapse as compared to control group. Incubation of isolated kidney mitochondria with UA (50, 100 and 200μM) manifested that UA can disrupt the electron transfer chain at complex II and III that leads to induction of reactive oxygen species (ROS) formation, lipid peroxidation, and glutathione oxidation. Disturbances in oxidative phosphorylation were also demonstrated through decreased ATP concentration and ATP/ADP ratio in UA-treated mitochondria. In addition, UA induced a significant damage in mitochondrial outer membrane. Moreover, MMP collapse, mitochondrial swelling and cytochrome c release were observed following the UA treatment in isolated mitochondria.

GENERAL SIGNIFICANCE

Both our in vivo and in vitro results showed that UA-induced nephrotoxicity is linked to the impairment of electron transfer chain especially at complex II and III which leads to subsequent oxidative stress.

Assessment of metabolic activity of human cells in solution and in polymer matrix with the use of metabolite-sensitive sensors

We developed metabolite-sensitive electrochemical sensors on the basis of electrodes modified with a thick film of carbon nanotubes. Modified electrodes provide efficient pre-adsorption of cellular metabolites and their sensitive detection using anodic square-wave voltammetry. On the electrode surface both adhered and non-adhered human cells produce three oxidation peaks at the potentials of +0.82, +1.05, and +1.17V attributed to three groups of cellular metabolites: amino acid-derived antioxidants including glutathione, guanine nucleotides, and also adenine nucleotides including ATP. The electrochemical response was well correlated with cell viability, intracellular ATP level and induction of apoptosis, as determined by independent assays. Developed sensors allow for robust and cost-effective assessment of ATP in cells in contrast to enzyme-based electrodes and conventional bioluminescent assay. Results can be used for rapid analysis of human cells for the purpose of medical diagnostics, transplantology, and toxicological screening. Additionally, we combined modified electrodes with human cells entrapped in agarose matrix. The resulting biosensor allowed for electrochemical monitoring of metabolic activity and death of cells within polymeric matrix that is of interest for tissue engineering applications.

Experimental results using 3-bromopyruvate in mesothelioma: in vitro and in vivo studies

Over many years we have taken advantage of the special metabolism of cancer cells involving an increased consumption of glucose associated with lactic acid production even in the presence of oxygen, a phenomenon referred to as the "Warburg effect", to counteract cancer cell growth. We have tested 3-bromopyruvate (3-BrPA), an inhibitor of pyruvate-associated reactions. Firstly, we tested this agent, in vitro, in two mesothelioma cell lines. Cellular response would appear to depend on the mode of administration (immediately or 24 h after seeding). Depending on the line, 3-BrPA induced a cytostatic or cytotoxic effect. This effect was accompanied by cell death induction even in cells highly refractory to cisplatin. Mitochondrial apoptotic death appeared to involve both lines; however, a different death pathway such as necrosis cannot be excluded. Interestingly, 3-BrPA leads to a diminution of the expression of the anti-apotptoic protein Mcl-1. We then tested 3-BrPA in vivo. Survival of nude mice bearing human mesothelioma was significantly prolonged (p < 0.0001). Toxicity and clinical studies should be performed to test 3- BrPA as local therapy for patients suffering from pleural or peritoneal mesothelioma. Association with cisplatin should be particularly considered.

Neoechinulin a impedes the progression of rotenone-induced cytotoxicity in PC12 cells

Neoechinulin A, an indole alkaloid from marine fungi, can protect PC12 cells from the cytotoxicity of 1-methyl-4-phenylpyridinium (MPP(+)), a Parkinson disease-inducing neurotoxin, by ameliorating downstream events resulting from mitochondrial complex I inactivation. However, the cytoprotective mechanisms remained unclear. In this study, by using rotenone, another parkinsonian-inducing neurotoxin targeting mitochondrial complex I, we investigated the cytoprotective mechanism of neoechinulin A. Rotenone-induced cell death was associated with accelerated glucose consumption, and excess glucose supplementation in the culture medium almost completely suppressed cell death, suggesting that glucose deficiency in the medium is critical for triggering cell death in this model. Co-treatment with neoechinulin A, but not neoechinulin A pre-treatment before rotenone exposure, significantly impeded cell death by rotenone. Although the presence of neoechinulin A did not affect the accelerated glycolytic turnover in rotenone-treated cells, it paradoxically decreased ATP levels in the cells, suggesting increased ATP consumption. Although the link between the decreased ATP levels and cytoprotection is not clear at present, it suggests that neoechinulin A may ameliorate rotenone toxicity by activating a cytoprotective machinery that requires ATP.

Glutamine supplementation in sick children: is it beneficial?

The purpose of this review is to provide a critical appraisal of the literature on Glutamine (Gln) supplementation in various conditions or illnesses that affect children, from neonates to adolescents. First, a general overview of the proposed mechanisms for the beneficial effects of Gln is provided, and subsequently clinical studies are discussed. Despite safety, studies are conflicting, partly due to different effects of enteral and parenteral Gln supplementation. Further insufficient evidence is available on the benefits of Gln supplementation in pediatric patients. This includes premature infants, infants with gastrointestinal disease, children with Crohn's disease, short bowel syndrome, malnutrition/diarrhea, cancer, severe burns/trauma, Duchenne muscular dystrophy, sickle cell anemia, cystic fibrosis, and type 1 diabetes. Moreover, methodological issues have been noted in some studies. Further mechanistic data is needed along with large randomized controlled trials in select populations of sick children, who may eventually benefit from supplemental Gln.

Understanding the central role of citrate in the metabolism of cancer cells

Cancers cells strongly stimulate glycolysis and glutaminolysis for their biosynthesis. Pyruvate derived from glucose is preferentially diverted towards the production of lactic acid (Warburg effect). Citrate censors ATP production and controls strategic enzymes of anabolic and catabolic pathways through feedback reactions. Mitochondrial citrate diffuses in the cytosol to restore oxaloacetate and acetyl-CoA. Whereas acetyl-CoA serves de novo lipid synthesis and histone acetylation, OAA is derived towards lactate production via pyruvate and / or a vicious cycle reforming mitochondrial citrate. This cycle allows cancer cells to burn their host's lipid and protein reserves in order to sustain their own biosynthesis pathways. In vitro, citrate has demonstrated anti-cancer properties when administered in excess, sensitizing cancer cells to chemotherapy. Understanding its central role is of particular relevance for the development of new strategies for counteracting cancer cell proliferation and overcoming chemoresistance.

Photocytotoxicity of hypocrellin B (HB) was enhanced by liposomalization in vitro

Hypocrellin B (HB) was encapsulated into a phosphatidylcholine liposome. Encapsulation of HB into liposomes not only improved the delivery of this photosensitizer but also increased its photodynamic efficacy compared to free HB molecules. Liposomal HB showed a higher cellular uptake than free HB as measured by confocal microscopy and was internalized into cultured HeLa cells by caveolar endocytosis, which was lipid-raft-dependent. Cell viability measurements demonstrated that liposomal HB was more phototoxic to HeLa cells than free HB as a result of the higher concentration of intracellular HB delivered by the liposomal formulation. The encapsulation of HB influenced the cell death pathway by an increased rate of necrotic cells after irradiation versus free HB, and a Type II (singlet oxygen) mechanism was responsible for the photocytotoxicity.

The curcuminoid CLEFMA selectively induces cell death in H441 lung adenocarcinoma cells via oxidative stress

CLEFMA or 4-[3,5-bis(2-chlorobenzylidene-4-oxo-piperidine-1-yl)-4-oxo-2-butenoic acid] is a curcuminoid being developed as an anticancer drug. We recently reported that it potently inhibits proliferation of various cancer cells. In this project, we investigated the effect of CLEFMA on gene expression profile in H441 lung adenocarcinoma cells, and studied its mechanism of action. In microarray data, we observed a deregulation of genes involved in redox and glutamate metabolism. Based on the affected ontologies, we hypothesized that antiproliferative activity of CLEFMA could be a result of the induction of reactive oxygen species (ROS). We tested this hypothesis by determining the levels of glutathione (GSH) and ROS in H441 cells treated with CLEFMA. We observed a rapid depletion of intracellular GSH/GSSG ratio. Using a cell-permeable fluorogenic substrate, we found that CLEFMA significantly induced ROS in a time- and dose-dependent manner (p < 0.05). Flow-cytometry with a mitochondria-selective fluorescent reporter of ROS indicated that the CLEFMA-induced ROS was of mitochondrial origin. In contrast to the cancer cells, the normal lung fibroblasts (CCL-151) did not show any increase in ROS and were resistant to CLEFMA-induced cell death. Furthermore, the addition of antioxidants, such as catalase, superoxide dismutase and N-acetylcysteine, rescued cancer cells from CLEFMA-induced cell death. Gene expression pathway analysis suggested that a transcription factor regulator Nrf2 is a pivotal molecule in the CLEFMA-induced deregulation of redox pathways. The immunoblotting of Nrf2 showed that CLEFMA treatment resulted in phosphorylation and nuclear translocation of Nrf2 in a time-dependent fashion. Based on these results, we conclude that induction of ROS is critical for the antiproliferative activity of CLEFMA and the Nrf2-mediated oxidative stress response fails to salvage H441 cells.

Role of nicotinamide in DNA damage, mutagenesis, and DNA repair

Nicotinamide is a water-soluble amide form of niacin (nicotinic acid or vitamin B3). Both niacin and nicotinamide are widely available in plant and animal foods, and niacin can also be endogenously synthesized in the liver from dietary tryptophan. Nicotinamide is also commercially available in vitamin supplements and in a range of cosmetic, hair, and skin preparations. Nicotinamide is the primary precursor of nicotinamide adenine dinucleotide (NAD⁺), an essential coenzyme in ATP production and the sole substrate of the nuclear enzyme poly-ADP-ribose polymerase-1 (PARP-1). Numerous in vitro and in vivo studies have clearly shown that PARP-1 and NAD⁺ status influence cellular responses to genotoxicity which can lead to mutagenesis and cancer formation. This paper will examine the role of nicotinamide in the protection from carcinogenesis, DNA repair, and maintenance of genomic stability.

Knipholone anthrone from Kniphofia foliosa induces a rapid onset of necrotic cell death in cancer cells

The present study examines the comparative cytotoxicity of knipholone (KP) and knipholone anthrone (KA) in leukaemic and melonocyte cancer cell lines. It was found that KA induces a rapid onset of cytotoxicity with IC(50) values ranging from 0.5 to 3.3 μM. In comparison to KA, KP was 70-480-times less toxic to cancer cells. Morphological and biochemical studies revealed that the cytotoxicity of KA was coupled with a quick loss of membrane integrity leading to necrotic cell death. The study identified KA as a new class of natural potential anticancer agent with a wide range of toxicological and pharmacological implications.

Retinal metabolic state of the proline-23-histidine rat model of retinitis pigmentosa

We determined the metabolic changes that precede cell death in the dystrophic proline-23-histidine (P23H) line 3 (P23H-3) rat retina compared with the normal Sprague-Dawley (SD) rat retina. Metabolite levels and metabolic enzymes were analyzed early in development and during the early stages of degeneration in the P23H-3 retina. Control and degenerating retinas showed an age-dependent change in metabolite levels and enzymatic activity, particularly around the time when phototransduction was activated. However, lactate dehydrogenase (LDH) activity was significantly higher in P23H-3 than SD retina before the onset of photoreceptor death. The creatine/phosphocreatine system did not contribute to the increase in ATP, because phosphocreatine levels, creatine kinase, and expression of the creatine transporter remained constant. However, Na(+)-K(+)-ATPase and Mg(2+)-Ca(2+)-ATPase activities were increased in the developing P23H-3 retina. Therefore, photoreceptor apoptosis in the P23H-3 retina occurs in an environment of increased LDH, ATPase activity, and higher-than-normal ATP levels. We tested the effect of metabolic challenge to the retina by inhibiting monocarboxylate transport with alpha-cyano-4-hydroxycinnamic acid or systemically administering the phosphodiesterase inhibitor sildenafil. Secondary to monocarboxylate transport inhibition, the P23H-3 retina did not demonstrate alterations in metabolic activity. However, administration of sildenafil significantly reduced LDH activity in the P23H-3 retina and increased the number of terminal deoxynucleotidyl transferase biotin-dUPT nick end-labeled photoreceptor cells. Photoreceptor cells with a rhodopsin mutation display an increase in apoptotic markers secondary to inhibition of a phototransduction enzyme (phosphodiesterase), suggesting increased susceptibility to altered cation entry.

Protocol for the quantitative assessment of DNA concentration and damage (fragmentation and nicks)

An ultrasensitive protocol is presented for the quantitative assessment of fragmented and nicked dsDNA using PicoGreen and consists of four methods. The first quantifies the concentration of DNA, whereas the second (quantitative complement of the Comet assay) quantifies the degree of DNA fragmentation seen in a typical DNA agarose electrophoresis gel. Both methods have sensitivity of 5 pg of DNA. The third method (quantitative counterpart of the electrophoresis-based qualitative apoptotic and necrotic DNA assays) quantifies the polyethylene glycol-fractionated small-size (0-1 kb) fragmented DNA. This method also detects up to 5 pg of damaged DNA and requires a minimum sample of quantity 0.2 ml of 2.5 microg ml(-1). The fourth method measures the percentage of DNA nicks by alkaline DNA unwinding and requires up to 15 pg of DNA sample. The time required for processing 10 DNA samples is 1/2, 1, 13 and 1 h for the first, second, third and fourth method, respectively.

NAD and axon degeneration: from the Wlds gene to neurochemistry

Neurodegenerative diseases have become a global issue due to the aging population. These disorders affect a vast patient population and represent a huge area of unmet therapeutic need. Axon degeneration is a common pathological character of those neurodegenerative diseases. It results in the loss of communication between neurons. Two decades ago, the Wallerian degeneration slow (Wlds) mouse strain was identified, in which the degeneration of transected axons is delayed. The phenotype is attributed to the overexpression of a chimeric protein Wlds which contains a short fragment of the ubiquitin assembly protein UFD2 and the full-length nicotinamide adenine dinucleotide (NAD) synthetic enzyme Nicotinamide mononucleotide adenylyl-transferase-1 (Nmnat-1). However, the underlying molecular mechanism remains largely unknown. Recently, it's reported by independent researchers that the full length coding sequence of mouse Nmnat-1 could mimic the axonal protective effect of the Wlds gene when overexpressed in primary neural cultures. Together with a significant number of subsequential reports, this finding highlighted the substantial role of nicotinamide adenine dinucleotide (NAD) in the process of axon degeneration. Here we reviewed the history of axon degeneration research from a neurochemical standpoint and discuss the potential involvement of NAD synthesis, NAD consumption and NAD-dependent proteins and small molecules in axon degeneration.

Emerging potential of thioredoxin and thioredoxin interacting proteins in various disease conditions

Reactive oxygen species (ROS) are known to be mediators of intracellular signaling pathways. However the excessive production of ROS may be detrimental to the cell as a result of the increased oxidative stress and loss of cell function. Hence, well tuned, balanced and responsive antioxidant systems are vital for proper regulation of the redox status of the cell. The cells are normally able to defend themselves against the oxidative stress induced damage through the use of several antioxidant systems. Even though the free radical scavenging enzymes such as superoxide dismutase (SOD) and catalase can handle huge amounts of reactive oxygen species, should these systems fail some reactive molecules will evade the detoxification process and damage potential targets. In such a scenario, cells recruit certain small molecules and proteins as 'rescue specialists' in case the 'bodyguards' fail to protect potential targets from oxidative damage. The thioredoxin (Trx) system thus plays a vital role in the maintenance of a reduced intracellular redox state which is essential for the proper functioning of each individual cell. Trx alterations have been implicated in many diseases such as cataract formation, ischemic heart diseases, cancers, AIDS, complications of diabetes, hypertension etc. The interactions of Trx with many different proteins and different metabolic and signaling pathways as well as the significant species differences make it an attractive target for therapeutic intervention in many fields of medical science. In this review, we present, the critical roles that thioredoxins play in limiting oxidant stress through either its direct effect as an antioxidant or through its interactions with other key signaling proteins (thioredoxin interacting proteins) and its implications in various disease models.

Oncolytic adenoviral mutants induce a novel mode of programmed cell death in ovarian cancer

Oncolytic adenoviral mutants have considerable activity in ovarian cancer. However, the mechanisms by which they induce cell death remain uncertain. dl922-947, which contains a 24 bp deletion in E1A CR2, is more potent than both E1A wild-type adenoviruses and the E1B-55K deletion mutant dl1520 (Onyx-015). We investigated the mode of death induced by three E1A CR2-deleted replicating adenoviruses in models of ovarian cancer and also the importance of E3 11.6 (adenovirus death protein) in determining this mode of death. Ovarian cancer cells were infected with dl922-947 (E3 11.6+) and dlCR2 (E3 11.6-). We also generated dlCR2 tSmac, which also encodes the gene for processed Smac/DIABLO. Classical apoptosis does not occur in adenoviral cell death and there is no role for mitochondria. Expression of Smac/DIABLO does not enhance cytotoxicity nor increase apoptotic features. A role for cathepsins and lysosomal membrane permeability was excluded. Autophagy is induced, but is not the mode of death and may act as a cell survival mechanism. There is no evidence of pure necrosis, while the presence of E3 11.6 does not modulate the mode or extent of cell death. Thus, E1A CR2-deleted oncolytic adenoviral cytotoxicity in ovarian cancer may define a novel mode of programmed cell death.

Dietary flavonoid apigenin is a potential inducer of intracellular oxidative stress: The role in the interruptive apoptotic signal

Apigenin is a representative dietary flavone (2-phenyl-4H-1-benzopyran-4-one) inhibiting cancer cell growth both in cell culture systems and in vivo. The prooxidant potential of apigenin was confirmed by the observations using flowcytometric and immunoblotting techniques that the intracellular accumulations of reactive oxygen species (ROS) and protein carbonyls were detected in the cells treated with apigenin in a dose-dependent manner. Conversely, chrysin (5,7-dihydroxyflavone) did not show any prooxidant effect. A structure-activity relationship data thus indicated that a 4'-monohydroxyl group, which can be oxidized to semiquinone radical but not up to quinone-like metabolite, is essential for prooxidant effect. When HL-60 cells were treated with not only a heme synthesis inhibitor succinyl acetone (SA) but also myeloperoxidase (MPO) inhibitors, the ROS level enhanced by apigenin was significantly reduced. The gathered data suggested that peroxidase-catalyzed production of apigenin B-ring phenoxyl radicals might be responsible for the prooxidant effect. This is supported by the observation that MPO is able to catalyze production of apigenin phenoxyl radicals, detected by an electron spin resonance-spin trapping technique. We also reveal that both SA and alpha-tocopherol enhance cellular susceptibility to apoptosis-inducing stimuli by apigenin. In conclusion, the prooxidant effect of apigenin is likely to oxidize a variety of thiols through the formation of phenoxyl radicals and thus seems to play a significant role in the abortive apoptotic pathway switching to necrotic cell death.

5'AMP-activated protein kinase alpha deficiency enhances stress-induced apoptosis in BHK and PC12 cells

5'AMP-activated protein kinase (AMPK) activation occurs under a variety of stress conditions but the role of this enzyme in the promotion or inhibition of stress-induced cell death is unclear. To address this issue, we transformed two different cell lines with shRNA-expressing plasmids, targeting the alpha subunit of AMPK, and verified AMPKalpha downregulation. The cell lines were then stressed by exposure to medium without glucose (PC12 cells) or with the viral thymidine kinase-specific DNA replication inhibitors: acyclovir, penciclovir and ganciclovir (herpes simplex virus thymidine kinase-expressing Baby Hamster Kidney cells). In non-AMPK-downregulated cells, these stress treatments induced AMPK upregulation and phosphorylation, leaving open the question whether the association of AMPK activation with stress-induced cell death reflects a successful death-promoting or an ineffective death-inhibiting activity. In AMPKalpha-deficient cells (expressing AMPKalpha-specific shRNAs or treated with Compound C) exposure to low glucose medium or DNA replication inhibitors led to an enhancement of cell death, indicating that, under the conditions examined, the role of activated AMPK is not to promote, but to protect from or delay stress-induced cell death.

Necrotic death without mitochondrial dysfunction-delayed death of cardiac myocytes following oxidative stress

Oxidative stress has been implicated in cell death in range of disease states including ischemia/reperfusion injury of the heart and heart failure. Here we have investigated the mechanisms of cell death following chronic exposure of cardiac myocytes to oxidative stress initiated by hydrogen peroxide. This exposure induced a delayed form of cell death with ultrastructural changes typical of necrosis, and that was accompanied by the release of lactate dehydrogenase and increased lipid peroxidation. However, this delayed death was not accompanied by the loss of mitochondrial membrane potential or caspase-3 activation. Furthermore, we could demonstrate that this delayed necrosis was at least partially prevented by pre-treatment with the hypertrophic stimuli endothelin-1 or leukemic inhibitory factor. Our results suggest that this delayed form necrosis may also comprise an ordered series of events involving pathways amenable to therapeutic modulation.

Apoptosis and necrosis: a review for surgeons

BACKGROUND

Orderly cell death, termed apoptosis, features a morphology that is distinct from necrotic, or accidental, cell death. As the body of literature on apoptotic cell death grows, it is difficult for practicing surgeons to stay current with the involved mechanisms and their biologic significance.

METHODS

A MEDLINE/PubMed literature search was conducted, followed by manual crossreferencing, to identify relevant articles published in the English language between 1972 and 2004.

RESULTS

Apoptosis is now known to be involved in numerous disease states. Ischemia-reperfusion injury and acute pancreatitis are but two surgical entities in which the balance of apoptotic and necrotic cell death has a profound effect on clinical outcome. Similarly, the timing and extent of apoptosis in immune cells are important factors that determine the outcome of septic patients.

CONCLUSIONS

As already demonstrated in animal models, further research in this field will target opportunities for therapeutic intervention, making it increasingly important for clinicians to be familiar with apoptosis and necrosis, and their roles in normal and pathologic states.

Spectroscopic properties and photodynamic effects of new lipophilic porphyrin derivatives: efficacy, localisation and cell death pathways

Photodynamic therapy (PDT) and photodynamic diagnostics (PDD) of cancer are based on the use of non-toxic dyes (photosensitisers) in combination with harmless visible light. This paper reports physicochemical properties, cell uptake, localisation as well as photodynamic efficiency of two novel lipophilic porphyrin derivatives, suitable for use as PDT sensitisers. Both compounds are characterised by high quantum yield of singlet oxygen generation which was measured by time-resolved phosphorescence. Photodynamic in vitro studies were conducted on three cancer cell lines. Results of cell survival tests showed negligible dark cytotoxicity but high phototoxicity. The results also indicate that cell death is dependent on energy dose and time following light exposure. Using confocal laser scanning microscopy both compounds were found to localise in the cytoplasm around the nucleus of the tumour cells. The mode of cell death was evaluated based on the morphological changes after differential staining. In summary, good photostability, high quantum yield of singlet oxygen and biological effectiveness indicate that the examined lipophilic porphyrin derivatives offer quite interesting prospects of photodynamic therapy application.

Caspase-3 dependent cleavage and activation of skeletal muscle phosphorylase b kinase

Phosphorylase b kinase (PhK) is a key enzyme involved in the conversion of glycogen to glucose in skeletal muscle and ultimately an increase in intracellular ATP. Since apoptosis is an ATP-dependent event, we investigated the regulation of skeletal muscle PhK during apoptosis. Incubation of PhK with purified caspase-3 in vitro resulted in the highly selective cleavage of the regulatory alpha subunit and resulted in a 2-fold increase in PhK activity. Edman protein sequencing of a stable 72 kD amino-terminal fragment and a 66 kD carboxy-terminal fragment revealed a specific caspase-3 cleavage site within the alpha subunit at residue 646 (DWMD G). Treatment of differentiated C2C12 mouse muscle myoblasts with the inducers of apoptosis staurosporine, TPEN, doxorubicin, or UV irradiation resulted in the disappearance of the alpha subunit of PhK as determined by immunoblotting, as well as a concurrent increase in caspase-3 activity. Moreover, induction of apoptosis by TPEN resulted in increased phosphorylase activity and sustained ATP levels throughout a 7 h time course. However, induction of apoptosis with staurosporine, also a potent PhK inhibitor, led to a rapid loss in phosphorylase activity and intracellular ATP, suggesting that PhK inhibition by staurosporine impairs the ability of apoptotic muscle cells to generate ATP. Thus, these studies indicate that PhK may be a substrate for caspase regulation during apoptosis and suggest that activation of this enzyme may be important for the generation of ATP during programmed cell death.

Assay for the quantification of small-sized fragmented genomic DNA

This paper presents a simple assay for the direct quantification of small-sized (up to 1000 bp) fragmented DNA based on the differential separation between large- and small-sized DNA by polyethylene glycol precipitation. The assay can be applied to as low as 1 microg ml(-1) DNA and has a very low DNA detection limit (0.01 microg ml(-1) fragmented DNA), which can be further lowered at least 10-fold with anion exchange chromatography. The assay quantifies for the first time a more direct indicator of the extent of DNA damage than the usually assessed DNA nicks and base modifications, since small-sized fragmented DNA represents an unrepairable DNA damage of necrotic and apoptotic events that are related to normal and abnormal biological conditions.

ClC-3 chloride channel is upregulated by hypertrophy and inflammation in rat and canine pulmonary artery

Cl- channels have been implicated in essential cellular functions including volume regulation, progression of cell cycle, cell proliferation and contraction, but the physiological functions of the ClC-3 channel are controversial. We tested the hypothesis that the ClC-3 gene (ClCn-3) is upregulated in hypertensive pulmonary arteries of monocrotaline-treated rats, and upregulated ClC-3 channel aids viability of pulmonary artery smooth muscle cells (PASMCs). Experimental pulmonary hypertension was induced in rats by a single subcutaneous administration of monocrotaline (60 mg kg(-1)). Injected animals developed characteristic features of pulmonary hypertension including medial hypertrophy of pulmonary arteries and right ventricular hypertrophy. Reverse transcriptase-polymerase chain reaction (RT-PCR), immunohistochemistry and Western immunoblot analysis indicated that histopathological alterations were associated with upregulation of the ClC-3 mRNA and protein expression in both smooth muscle cells of hypertensive pulmonary arteries and in cardiac myocytes. RT-PCR analysis of mRNA, extracted from canine cultured PASMCs, indicated that incubation with the inflammatory mediators endothelin-1 (ET-1), platelet-derived growth factor (PDGF), interleukin-1beta (IL-1beta) and tumor necrosis factor alpha (TNF alpha), but not transforming growth factor beta (TGFbeta), upregulated ClC-3 mRNA. Adenovirus-mediated delivery and overexpression of ClC-3 in canine PASMCs improved cell viability against increasing concentrations of hydrogen peroxide (H2O2, range 50-250 microM). In conclusion, upregulation of ClC-3 in rat hypertensive lung and heart is a novel observation. Our functional data suggest that upregulation of ClC-3 is an adaptive response of inflamed pulmonary artery, which enhances the viability of PASMCs against reactive oxygen species.

Hsp27 consolidates intracellular redox homeostasis by upholding glutathione in its reduced form and by decreasing iron intracellular levels

Small stress proteins [small heat shock proteins (sHsps)] are molecular chaperones that modulate the ability of cells to respond to oxidative stress. The current knowledge concerning the protective mechanism generated by the expression of mammalian heat shock protein-27 (Hsp27) that allows cells to increase their resistance to oxidative stress is presented. We describe the effects mediated by Hsp27 expression toward crucial enzymes such as glucose-6-phosphate dehydrogenase and glutathione reductase that uphold glutathione in its reduced form. New data are presented showing that the expression of sHsps correlates with a drastic decrease in the intracellular level of iron, a catalyzer of hydroxyl radical (OH( . )) generation. A decreased ability of sHsps expressing cells to concentrate iron will therefore end up in a decreased level of oxidized proteins. In addition, we propose a role of Hsp27 in the presentation of oxidized proteins to the proteasome degradation machinery. We also present an analysis of several Hsp27 mutants that suggests that the C-terminal part of this stress protein is essential for its protective activity against oxidative stress.

Radiation-induced apoptosis of stem/progenitor cells in human umbilical cord blood is associated with alterations in reactive oxygen and intracellular pH

To investigate the sensitivity of human hematopoietic stem cell populations to radiation and its relevance to intracellular events, specifically alteration in cellular energy production systems, we examined the frequency of apoptotic cells, generation of superoxide anions (O*2-), and changes in cytosol pH in umbilical cord blood (UCB) CD34+/CD38-, CD34+/CD38+ and CD34-/CD38+ cells before and after 5Gy of X-irradiation. Human UCB mononucleated cells were used in this study. After X-irradiation and staining subgroups of the cells with fluorescence (FITC, PE, or CY)-labeled anti-CD34 and anti-CD38 antibodies, analyses were performed by FACScan using as stains 7-amino-actinomycin D (7-AAD) for the detection of apoptosis, and hydroethidine (HE) for the measurement of O*2- generation in the cells. For intracellular pH, image analysis was conducted using confocal laser microscopy after irradiation and staining with carboxy-SNAFR-1. The frequency of apoptotic cells, as determined by cell staining with 7-AAD, was highest in the irradiated CD34+/CD38- cell population, where the level of O*2- detected by the oxidation of HE was also most highly elevated. Intracellular pH measured with carboxy-SNARF-1-AM by image cytometer appeared to be lowest in the same irradiated CD34+/CD38- cell population, and this intracellular pH decreased as early as 4 h post-irradiation, virtually simultaneous with the significant elevation of O*2- generation. These results suggest that the CD34+/CD38- stem cell population is sensitive to radiation-induced apoptosis as well as production of intracellular O*2-, compare to more differentiated CD34+/CD38+ and CD34-/CD38+ cells and that its intracellular pH declines at an early phase in the apoptosis process.