Diabetic nephropathy and multiorgan protection. Part II

Diabetic nephropathy (DN) presents a complex pathogenesis in which both the vascular system and the metabolism, in its complexity and mainly glucidic metabolism, are involved. Together with the glucid metabolism, lipid metabolism, anemia, oxidative stress, generalised inflammation, vitamin D disorders and smoking participate in DN pathogenesis. All these factors that disturb the homeostasis of the patient with DN require protective factors which will be presented in the second part of the paper. Like hypotensive medication, and especially the inhibitors of the renin angiotensin aldosterone (RAAS) system, antiproteinuric medication, and especially intensive control of glycaemia that have an important protective role, the pathogenic factors mentioned above also require protective measures. As they interest the whole organism in DN and in DM, respectively, we speak about multiple organ protection or multiorgan protection. The concept of multiorgan protection is especially important in DM. Although sometimes, some measures with multiorgan protective character are applied in current practice, it is necessary that they should be gathered and applied within a well established framework, a fact that is achieved by the concept of multiorganprotection. Diabetes mellitus, requires multiple measures of protection because of its vascular and metabolic complications. Diabetic nephropathy represents an important complication of diabetes mellitus, frequently associated with its other complications. The first part of the paper presented the concept of multiorgan protection, as well as some of the main protective measures: control of blood pressure mainly by means of inhibitors of the renine angiotensine aldosterone system, glycaemia monitoring and antiproteinuric treatment. The second part of the paper refers to protective measures used in diabetes mellitus, and diabetic nephropathy, respectively, regarding control of the anaemia, of endothelial disturbances, of the metabolism of lipids, of oxidative stress, of inflammation, smoking, of the metabolism of vitamin D, respectively. Diabetic nephropathy, by the complexity of its lesions, as well as by the complications of diabetes mellitus, cannot be regarded as separate from the organism seen as a unitary whole, a reason because of which the measures of protection are not limited only to the kidney, they must address all organs and metabolism in general, requiring measures of multiorgan protection.

Metallothionein gene expression in liver of rats exposed to cadmium and supplemented with zinc and selenium

Cadmium (Cd), one of the most widely distributed heavy metals, is highly toxic to humans and animals. It is well known that zinc (Zn) and selenium (Se) administration reduce the Cd-induced toxicity and that metallothioneins can have a protective effect to mitigate Cd toxicity in biological systems. In this study we report the expression analysis of the two metallothioneines gene classes MT-1 and MT-2 as well as the total metalloprotein content in the liver of rats exposed to Cd (200 ppm), Cd + Zn (200 ppm + 500 ppm), Cd + Se (200 ppm + 0.1 ppm) or Cd + Zn + Se (200 ppm + 500 ppm + 0.1 ppm) in their drinking water for 35 days. Metals accumulation was quantified in rat liver. Cd decreased significantly the hepatic concentrations of Se and increased those of Zn. The treatment of Cd-exposed rats with Se alone or combined with Zn reversed the Cd-induced depletion of Se concentrations in the liver. However, Zn or Zn + Se administration significantly increased the liver Cd uptake and had no effect on the Cd-induced increase in hepatic concentrations of Zn. The molecular assay showed a decreasing trend of MT-1 relative gene expression levels in animals supplemented with Zn (6.87-fold), Se (3.58-fold), and their combination (1.69-fold) when compared to Cd-treated animals (16.22-fold). Upregulation of the MT-2 expression were recorded in all conditions, although fold induction levels were less pronounced than MT-1 expressions. Our data suggest that the well-established protective effect of Zn and Se against Cd-induced toxicity passes through non-MT gene expression mechanisms, being more dependent on the oxidative stress status of the cell.

1,5-anhydro-D-fructose and its derivatives: biosynthesis, preparation and potential medical applications

1,5-Anhydro-D-fructose (AF) was first found in fungi and red algae. It is produced by the degradation of glycogen, starch and maltosaccharides with α-1,4-glucan lyase (EC 4.2.2.13). In vivo, AF is metabolized to 1,5-anhydro-D-glucitol (AG), ascopyrone P (APP), microthecin and other derivatives via the anhydrofructose pathway. The genes coding for the enzymes in this pathway have been cloned, enabling the large-scale production of AF and related products in a cell-free reactor. The possible applications of these products in medicine have been evaluated using both in vitro and in vivo systems. Thus AF is a useful anticariogenic agent as it inhibits the growth of the oral pathogen Streptococcus mutans, impairing the production of plaque-forming polysaccharides and lactic acid. AF also shows anti-inflammatory and anticancer effects. AG is used as a diabetic marker for glycemic control. AG also stimulates insulin secretion in insulinoma cell lines. in vivo, APP has been shown to lengthen the life span of cancer-afflicted mice. It interferes with tumor growth and metastasis by its cidal effects on fast multiplying cells. Microthecin inhibits the growth of the human pathogen Pseudomonas aeruginosa PAO1, particularly under anaerobic conditions. The pharmaceutical usefulness of the other AF metabolites 1,5-anhydro-D-mannitol,1-deoxymannojirimycin, haliclonol, 5-epipentenomycin I, bissetone, palythazine, isopalythazine, and clavulazine remains to be investigated. In this review AF and its metabolites as the bioactive natural products for their pharmaceutical potentials are discussed.

Reduced expression of IFIH1 is protective for type 1 diabetes

IFIH1 (interferon induced with helicase C domain 1), also known as MDA5 (melanoma differentiation-associated protein 5), is one of a family of intracellular proteins known to recognise viral RNA and mediate the innate immune response. IFIH1 is causal in type 1 diabetes based on the protective associations of four rare variants, where the derived alleles are predicted to reduce gene expression or function. Originally, however, T1D protection was mapped to the common IFIH1 nsSNP, rs1990760 or Thr946Ala. This common amino acid substitution does not cause a loss of function and evidence suggests the protective allele, Ala(946), may mark a haplotype with reduced expression of IFIH1 in line with the protection conferred by the four rare loss of function alleles. We have performed allele specific expression analysis that supports this hypothesis: the T1D protective haplotype correlates with reduced IFIH1 transcription in interferon-β stimulated peripheral blood mononuclear cells (overall p = 0.012). In addition, we have used multiflow cytometry analysis and quantitative PCR assays to prove reduced expression of IFIH1 in individuals heterozygous for three of the T1D-associated rare alleles: a premature stop codon, rs35744605 (Glu627X) and predicted splice variants, rs35337543 (IVS8+1) and rs35732034 (IVS14+1). We also show that the nsSNP, Ile923V, does not alter pre-mRNA levels of IFIH1. These results confirm and extend the new autoimmune disease pathway of reduced IFIH1 expression and protein function protecting from T1D.

Extremolyte-like applicability of an archaeal exopolymer, poly-gamma-L-glutamate

An extremely halophilic archaeon Natrialba aegyptiaca produces extracellular poly-gamma-glutamate (PGA), in which only L-glutamate is polymerized via gamma-amide linkages. We examined the extremolyte-like applicability of archaeal PGA and found the ameliorating effects of L-PGA on the resistibility to freeze-thawing and proteolysis, thermostability, and alkalotolerance of a model enzyme, labile DNA ligase. For example, the coexistence of low (e.g. 0.01 mg mL(-1)) and high (e.g. 0.1 mg mL(-1)) concentrations of L-PGA with an average molecular mass of 1000 kDa increased the midpoint of thermal inactivation of DNA ligase by about 15 degrees C and 18 degrees C, respectively, and the model enzyme further remained active even under extremely alkaline conditions of pH 11.4 in the presence of the high concentration of L-PGA. This is the first characterization of the stereo-regular PGA molecules as atypical extremolytes. L-PGA from extremophiles has great potential as a bio-based protectant (or stabilizer) with industrial versatility.

Rapid method for isolation of desiccation-tolerant strains and xeroprotectants

A novel biotechnological process has been developed for the isolation of desiccation-tolerant microorganisms and their xeroprotectants, i.e., compatible solutes involved in long-term stability of biomolecules in the dry state. Following exposure of soil samples to chloroform, we isolated a collection of desiccation-tolerant microorganisms. This collection was screened for the production of xeroprotectants by a variation of the bacterial milking (osmotic downshock) procedure and by a novel air-drying/rehydration ("dry milking") incubation method. The resultant solutes were shown to protect both proteins and living cells against desiccation damage, thereby validating them as xeroprotectants. Nuclear magnetic resonance (NMR) analytical studies were performed to identify the xeroprotectants; synthetic mixtures of these compounds were shown to perform similarly to natural isolates in drying experiments with proteins and cells. This new approach has biotechnological and environmental implications for the identification of new xeroprotectants of commercial and therapeutic value.

Photoprotective compounds from marine organisms

The substantial loss in the stratospheric ozone layer and consequent increase in solar ultraviolet radiation on the earth's surface have augmented the interest in searching for natural photoprotective compounds in organisms of marine as well as freshwater ecosystems. A number of photoprotective compounds such as mycosporine-like amino acids (MAAs), scytonemin, carotenoids and several other UV-absorbing substances of unknown chemical structure have been identified from different organisms. MAAs form the most common class of UV-absorbing compounds known to occur widely in various marine organisms; however, several compounds having UV-screening properties still need to be identified. The synthesis of scytonemin, a predominant UV-A-photoprotective pigment, is exclusively reported in cyanobacteria. Carotenoids are important components of the photosynthetic apparatus that serve both light-harvesting and photoprotective functions, either by direct quenching of the singlet oxygen or other toxic reactive oxygen species or by dissipating the excess energy in the photosynthetic apparatus. The production of photoprotective compounds is affected by several environmental factors such as different wavelengths of UVR, desiccation, nutrients, salt concentration, light as well as dark period, and still there is controversy about the biosynthesis of various photoprotective compounds. Recent studies have focused on marine organisms as a source of natural bioactive molecules having a photoprotective role, their biosynthesis and commercial application. However, there is a need for extensive work to explore the photoprotective role of various UV-absorbing compounds from marine habitats so that a range of biotechnological and pharmaceutical applications can be found.

[Renoprotective effect of adiponectin through an antioxidant mechanism in streptozotocin- induced diabetic rats]

OBJECTIVE

To investigate the renoprotective effect of adiponectin in streptozotocin (STz)-induced diabetic rats and explore its association with oxidation stress.

METHODS

Type 2 diabetes mellitus was induced in rats by high-lipids and high-sucrose feeding and intraperitoneal STZ injection. The recombinant plasmid pIRES2-EGFP-gAd expressing globular adiponectin was intraperitoneally injected in the rats mediated by liposome. Thirty-two Wistar rats were randomized into 4 groups, namely the normal control group (NC), diabetic group without any therapy (DM), diabetic group treated with pIRES2-EGFP-gAd (DA) and diabetic group treated with pIRES2-EGFP (DP). After the corresponding treatments for 8 weeks, the blood glucose, HbA1c and urine albumin excretion rate (UAER) were measured, and the kidneys were collected to determine the production of reactive oxygen species (ROS) and assess renal pathologies. Immunohistochemistry and Western blot were employed to determine the protein levels of endothelial nitric oxide synthesis (eNOS) and phosphorylated AMP-activated protein kinase (pAMPK).

RESULTS

UAER and ROS production increased significantly in DM group as compared with that in the control group (P<0.05), while no significant differences were found in UARE among the DM, DA, and DP groups (P>0.05). Blood glucose level, HbA1c and ROS were significantly decreased in DA group in comparison with those in DM group (P<0.05). Glomerular hypetrophy, mesangial expansion, basal membrane thickening, tubular epithelial cells cavitation and exfoliation, and mononuclear lymphocyte infiltration occurred in DM group, while these changes were ameliorated in gAd transfection group. The renal expression levels of eNOS and p-AMPK proteins in DM group were significantly lower than those in the control group (P<0.05) and gAd transfection group (P<0.05).

CONCLUSIONS

The renoprotective effect of adiponectin may be at least partially mediated by the activation of the AMPK signaling passway, ROS production inhibition, relief of the oxidative stress, and up-regulation of eNOS expression in the renal tissue of diabetic rats.

Bioactive microbial metabolites from glycyrrhetinic acid

Biotransformation of 18beta-glycyrrhetinic acid, using Absidia pseudocylinderospora ATCC 24169, Gliocladium viride ATCC 10097 and Cunninghamella echinulata ATCC 8688a afforded seven metabolites, which were identified by different spectroscopic techniques (1H, 13C NMR, DEPT, 1H-1H COSY, HMBC and HMQC). Three of these metabolites, viz. 15alpha-hydroxy-18alpha-glycyrrhetinic acid, 13beta-hydroxy-7alpha,27-oxy-12-dihydro-18beta-glycyrrhetinic acid and 1alpha-hydroxy-18beta-glycyrrhetinic acid are new. The 13C NMR data and full assignment for the known metabolite 7beta, 15alpha-dihydroxy-18beta-glycyrrhetinic acid are described here for the first time. The major metabolites were evaluated for their hepatoprotective activity using different in vitro and in vivo models. These included protection against FeCl3/ascorbic acid-induced lipid peroxidation of normal mice liver homogenate, induction of nitric oxide (NO) production in rat macrophages and in vivo hepatoprotection against CCl4-induced hepatotoxicity in albino mice.

Ammonia toxicity to the brain: effects on creatine metabolism and transport and protective roles of creatine

Hyperammonemia can provoke irreversible damage to the developing brain, with the formation of cortical atrophy, ventricular enlargement, demyelination or gray and white matter hypodensities. Among the various pathogenic mechanisms involved, alterations in cerebral energy have been demonstrated. In particular, we could show that ammonia exposure generates a secondary deficiency in creatine in brain cells, by altering the brain expression and activity of the genes allowing creatine synthesis (AGAT and GAMT) and transport (SLC6A8). On the other hand, it is known that creatine administration can exert protective effects in various neurodegenerative processes. We could also show that creatine co-treatment under ammonia exposure can protect developing brain cells from some of the deleterious effects of ammonia, in particular axonal growth impairment. This article focuses on the effects of ammonia exposure on creatine metabolism and transport in developing brain cells, and on the potential neuroprotective properties of creatine in the brain exposed to ammonium.

Vitamin C and the role of citrus juices as functional food

The literature on the content and stability of vitamin C (ascorbic acid, AA) in citrus juices in relation to industrial practices is reviewed. The role of vitamin C from citrus juices in human diet is also reviewed. Citrus fruits and juices are rich in several types of bioactive compounds. Their antioxidant activity and related benefits derive not only from vitamin C but also from other phytochemicals, mainly flavonoids. During juice processing, temperature and oxygen are the main factors responsible for vitamin C losses. Non-thermal processed juices retain higher levels of vitamin C, but economic factors apparently delay the use of such methods in the citrus industry. Regarding packing material, vitamin C in fruit juice is quite stable when stored in metal or glass containers, whereas juice stored in plastic bottles has a much shorter shelf-life. The limiting step for vitamin C absorption in humans is transcellular active transport across the intestinal wall where AA may be oxidized to dehydroascorbic acid (DHAA), which is easily transported across the cell membrane and immediately reduced back to AA by two major pathways. AA bioavailability in the presence of flavonoids has yielded controversial results. Whereas flavonoids seem to inhibit intestinal absorption of AA, some studies have shown that AA in citrus extract was more available than synthetic ascorbic acid alone. DHAA is reported to possess equivalent biological activity to AA, so recent studies often consider the vitamin C activity in the diet as the sum of AA plus DHAA. However, this claimed equivalence should be carefully reexamined. Humans are one of the few species lacking the enzyme (L-gulonolactone oxidase, GLO) to convert glucose to vitamin C. It has been suggested that this is due to a mutation that provided a survival advantage to early primates, since GLO produces toxic H2O2. Furthermore, the high concentration of AA (and DHAA) in neural tissues could have been the key factor that caused primates (vertebrates with relative big brain) to lose the capacity to synthesize vitamin C. Oxidative damage has many pathological implications in human health, and AA may play a central role in maintaining the metabolic antioxidant response. The abundance of citrus juices in the Mediterranean diet may provide the main dietary source for natural vitamin C.

Protective effect of melatonin against chlorophyll degradation during the senescence of barley leaves

Melatonin (N-acetyl-5-methoxytryptamine) is a highly conserved molecule whose presence is not exclusive to the animal kingdom. Indeed, numerous studies have demonstrated its presence in plants, where the possible role(s) of this indoleamine is (are) under active investigation. The present work aims to further our knowledge in this respect and presents the results of a study of the effect that melatonin has on foliar senescence. Barley leaves treated with melatonin solutions clearly slowed down the senescence process, as estimated from the chlorophyll lost in leaves. This effect of melatonin was concentration dependent, with an optimal response being obtained at 1 mm melatonin, after 48 hr of incubation in darkness. The already known effects of the phytohormones, kinetin, and abscisic acid, were also assayed. Of the phytohormone and melatonin combinations assayed, 1 mm melatonin presented the best protection against senescence. The levels of endogenous melatonin in control leaves were measured by liquid chromatography with fluorescence detection and in leaves treated with different exogenous melatonin concentrations (to demonstrate the absorption capacity of leaves). The possible physiological implications of this newly revealed action of melatonin in foliar senescence are discussed.

[Superoxide dismutase mimetics: possible clinical applications]

Superoxide, and its derivatives hydrogen peroxide, hydrogen peroxide, and peroxynitrite, play an important role in aging and in several diseases, including cancer, diabetes, inflammation, neurodegenerative and vascular disorders. Increased level of reactive oxygen species leading to severe organ damage could also be a consequence of applied therapy, such as radiation therapy, chemotherapy,reperfusion after ischemia, or transplantation. A new approach to protect normal tissues without jeopardizing the efficacy of treatment may be to apply specific catalytic antioxidants as adjuncts to the therapy. In this review a number of synthetic low-molecular-weight agents are discussed that may be used as mimetics of superoxide dismutase enzymes (SODm) to treat diseases of various etiologies and to protect healthy tissues during therapy.

Interspecies comparison of the glucuronidation processes in the man, monkey, pig, dog and rat

OBJECTIVES

The study of interspecies differences in glucuronidation processes in the man, monkey, pig, dog and rat using liver microsomal fraction. The study is focused on determination of the enzyme activity of UGT1A6 (having also a toxicological importance) in microsomes of different species.

METHODS

For determination of glucuronides formed, an HPLC method with UV detection and LC-MS characterization was used. p-Nitrophenol and 4-methylumbelliferon and silybin were chosen as model substrates.

RESULTS

The data presented in this paper show an overall similarity in kinetic parameters of the UGT1A6 with p-nitrophenol and 4-methylumbelliferon for man, pig and monkey. The pattern of silybin glucuronides formed in monkey and dog samples are relatively close to this of the man.

CONCLUSIONS

For studies of glucuronidation of xenobiotics where the role UGT1A6 is expected, the use of pig and monkey microsomes should be considered. As an optimal model for study of silybin glucuronidation, both the rhesus monkey and dog (Beagle) seem to be the best models. To elucidate the role of the UGT forms involved in metabolism of silybin, the experiments with recombinant UGT enzymes are needed.

Role of phosphatidylcholine saturation in preventing bile salt toxicity to gastrointestinal epithelia and membranes

BACKGROUND AND AIM

The mechanism which protects the biliary and intestinal mucosa from the detergent properties of bile acids is not fully understood. We employed three contrasting in vitro model systems (human red blood cells, polarized intestinal [Caco-2] cells, and synthetic liposomes), to compare the efficacy of saturated and unsaturated phosphatidylcholine (PC) to protect cells and membranes from bile salt injury.

METHODS

Hemolysis of red blood cells, electrical resistance across confluent monolayers of Caco-2 cells, and disruption of synthetic PC liposomes were assessed after incubation with varying concentrations of bile salt (sodium deoxycholate) alone or in the presence of saturated or unsaturated PC.

RESULTS

The hemolytic activity of deoxycholate on red blood cells was observed at > or =2 mM, and could be blocked by equimolar concentration or greater of both saturated or unsaturated PC. In contrast, exposure of Caco-2 cells to deoxycholate at > or =0.8 mM induced a maximal decrease in resistance, which was reversed by > or =0.8 mM unsaturated PC or 5 mM saturated PC. Similarly, synthetic liposomes were permeabilized by 0.8 mM deoxycholate and were protected by a lower concentration of unsaturated PC (2 mM) than saturated (5 mM).

CONCLUSIONS

Cells can show variable resistance to bile salt toxicity. Extracellular PC, especially in the unsaturated state, can directly protect cell and artificial membranes from bile salt injury. These findings support a role for biliary PC in the formation of mixed micelles that have low cytotoxic properties.

Protective functions of heme oxygenase-1 and carbon monoxide in the respiratory system

The respiratory system, including the lung and upper airways, succumbs to injury and disease through acute or chronic exposures to adverse environmental agents, in particular, those that promote increased oxidative or inflammatory processes. Cigarette smoke and other forms of particulate or gaseous air pollution, allergens, microorganisms infections, and changes in inspired oxygen may contribute to lung injury. Among the intrinsic defenses of the lung, the stress protein heme oxygenase-1 constitutes an inducible defense mechanism that can protect the lung and its constituent cells against such insults. Heme oxygenases degrade heme to biliverdin-IXalpha, carbon monoxide, and iron, each with candidate roles in cytoprotection. At low concentrations, carbon monoxide can confer similar cyto and tissue-protective effects as endogenous heme oxygenase-1 expression, involving antioxidative, antiinflammatory, antiproliferative, and antiapoptotic effects. Lung protection by heme oxygenase-1 or its enzymatic reaction products has been demonstrated in vitro and in vivo in a number of pulmonary disease models, including acute lung injury, cigarette smoke-induced lung injury/chronic obstructive pulmonary disease, interstitial lung diseases, ischemia/reperfusion injury, and asthma/airway inflammation. This review summarizes recent findings on the functions of heme oxygenase-1 in the respiratory system, with an emphasis on possible roles in disease progression and therapies.

Selective effects of diallyl disulfide, a sulfane sulfur precursor, in the liver and Ehrlich ascites tumor cells

The present in vivo studies demonstrated that diallyl disulfide (DADS), occurring in garlic, elevated hepatic sulfane sulfur level and activities of gamma-cystathionase and 3-mercaptopyruvate sulfotransferase in healthy mice but did not affect the hepatic glutathione level. DADS efficiently corrected the concentrations of glutathione and sulfane sulfur, and ameliorated gamma-cystathionase activity that had been lowered in the livers of Ehrlich ascites tumor-bearing mice. In Ehrlich ascites tumor cells, diallyl disulfide did not alter bound sulfane sulfur level, sulfotransferases activity or glutathione level. These data indicate that this compound is capable of acting efficiently and selectively only in the liver and can be used for hepatoprotection during chemotherapy.

Protective effects of erdosteine and vitamins C and E combination on ischemia-reperfusion-induced lung oxidative stress and plasma copper and zinc levels in a rat hind limb model

The aim of this study was to investigate the protective effects of erdosteine and vitamins C and E (VCE) on the lungs after performing hind limb ischemia-reperfusion (I/R) by assessing oxidative stress, plasma copper (Cu), and zinc (Zn) analysis. The animals were divided randomly into four groups as nine rats each as follows: control, I/R, I/R plus erdosteine, and I/R plus VCE combination. I/R period for 60 min was performed on the both hind limbs of all the rats in the groups of I/R, erdosteine with I/R, VCE with I/R allowing 120 min of reperfusion. The animals received orally erdosteine one time in a day and 3 days before I/R in the erdosteine group. In the VCE group, the animals VCE combination received one time in a day and 3 days before I/R, although placebo was given to control and I/R group animals. Lung lipid peroxidation (malondialdehyde [MDA]) level, superoxide dismutase (SOD), and catalase activities were increased, although lung glutathione (GSH) and plasma Zn levels decreased in I/R group in lung tissue compared with the control group. Serum MDA level, creatine kinase, and lactate dehydrogenase activities were increased in I/R group compared with the control. Lung MDA and plasma Zn levels and lung SOD activity were decreased by erdosteine administration, whereas lung GSH levels after I/R increased. The plasma Zn levels and lung SOD activity were decreased by VCE administration, although the plasma Cu and lung GSH levels increased after I/R. In conclusion, erdosteine has an antioxidant role on the values in the rat model, and it has more protective affect than in VCE in attenuating I/R-induced lung injury in rats.

Poly(ADP-ribose) polymerase offers protection against oxidative and alkylation damage to the nuclear and mitochondrial genomes of the retinal pigment epithelium

PURPOSE

To investigate the role of poly(ADP-ribose)-polymerase (PARP) in protecting against oxidative (H(2)O(2)) and alkylation (MMS) damage to the nDNA and mtDNA genomes of the retinal pigment epithelium (RPE). We further hypothesized that PARP ribosylation enzymatic activity is required to facilitate efficient nDNA and mtDNA repair to enable the RPE to survive chronic oxidative stress exposure.

METHODS

Cellular sensitivity to H(2)O(2) and MMS was determined by the MTT and LDH assays. PARP ribosyl(ation) activity was inhibited by supplementation of 3-aminobenzamide (competitive PARP inhibitor). The susceptibility and repair capacities of nuclear and mitochondrial genomes were assessed by quantitative PCR and PARP activity assessed using an enzyme assay.

RESULTS

This study demonstrated that cells lacking ribosyl(ation) activity had a significantly lower lesion repair capacity in both nDNA and mtDNA (p < 0.05), which culminated in reduced cell viability after H(2)O(2) exposure only (p < 0.05). Furthermore, the mtDNA demonstrated a significantly greater sensitivity compared to nDNA to both oxidative and alkylation damage (p < 0.05).

CONCLUSION

PARP activity has an important role in providing the RPE with the high oxidative tolerance required for this cell type to survive the constant reactive oxygen species attack in vivo for several decades.

Efficient protection by cationized catalase against H2O2 injury in primary cultured alveolar epithelial cells

Increasing evidence suggests that hydrogen peroxide plays an important role in alveolar epithelial injury produced during many inflammatory lung diseases. In this study, the successful prevention of hydrogen peroxide (H(2)O(2))-induced injury in primary cultured rabbit alveolar epithelial cells by cationized catalase is described. Cationized catalase was synthesized by direct chemical modification to enhance its association with alveolar epithelial cells. Cationized catalase exhibited a 22.3-fold higher cellular association at 2 h than native catalase, and incubation of cationized catalase with the cells produced a 2.19-fold intracellular catalase activity, which suggested that cationized catalase distributed both to the cell membrane and into the cell interior. Cationized catalase markedly suppressed H(2)O(2)-induced cell injury. In addition, electron spin resonance spectrometry analysis revealed that cationized catalase effectively eliminated H(2)O(2) produced in the medium by glucose plus glucose oxidase. On the other hand, polyethylene glycol-modified catalase (PEG-catalase) did not have any protective effect against H(2)O(2)-induced cell injury although PEG-catalase exhibited a 2.49-fold higher cellular association at 2 h than native catalase. These results suggest that cationization of catalase is a promising strategy for the treatment of many of inflammatory lung diseases.

The Heme Catabolic Pathway and its Protective Effects on Oxidative Stress‐Mediated Diseases

Bilirubin, the principal bile pigment, is the end product of heme catabolism. For many years, bilirubin was thought to have no physiological function other than that of a waste product of heme catabolism--useless at best and toxic at worst. Although hyperbilirubinemia in neonates has been shown to be neurotoxic, studies performed during the past decade have found that bilirubin has a number of new and interesting biochemical and biological properties. In addition, there is now a strong body of evidence suggesting that bilirubin may have a beneficial role in preventing oxidative changes in a number of diseases including atherosclerosis and cancer, as well as a number of inflammatory, autoimmune, and degenerative diseases. The results also suggest that activation of the heme oxygenase and heme catabolic pathway may have beneficiary effects on disease prevention either through the action of bilirubin or in conjunction with bilirubin. If so, it may be possible to therapeutically induce heme oxygenase, increase bilirubin concentrations, and lower the risk of oxidative stress-related diseases.

Stromal and epithelial caveolin-1 both confer a protective effect against mammary hyperplasia and tumorigenesis: Caveolin-1 antagonizes cyclin D1 function in mammary epithelial cells

Here, we investigate the role of caveolin-1 (Cav-1) in breast cancer onset and progression, with a focus on epithelial-stromal interactions, ie, the tumor microenvironment. Cav-1 is highly expressed in adipocytes and is abundant in mammary fat pads (stroma), but it remains unknown whether loss of Cav-1 within mammary stromal cells affects the differentiated state of mammary epithelia via paracrine signaling. To address this issue, we characterized the development of the mammary ductal system in Cav-1-/- mice and performed a series of mammary transplant studies, using both wild-type and Cav-1-/- mammary fat pads. Cav-1-/- mammary epithelia were hyperproliferative in vivo, with dramatic increases in terminal end bud area and mammary ductal thickness as well as increases in bromodeoxyuridine incorporation, extracellular signal-regulated kinase-1/2 hyperactivation, and up-regulation of STAT5a and cyclin D1. Consistent with these findings, loss of Cav-1 dramatically exacerbated mammary lobulo-alveolar hyperplasia in cyclin D1 Tg mice, whereas overexpression of Cav-1 caused reversion of this phenotype. Most importantly, Cav-1-/- mammary stromal cells (fat pads) promoted the growth of both normal mammary ductal epithelia and mammary tumor cells. Thus, Cav-1 expression in both epithelial and stromal cells provides a protective effect against mammary hyperplasia as well as mammary tumorigenesis.

Apolipoprotein E epsilon4 offers protection against age-related macular degeneration

BACKGROUND

In many previous studies, age-related macular degeneration (ARMD) has been linked to a variety of different risk factors. The publications have debated whether apolipoprotein E (apoE) epsilon4 serves as a potential protective factor in the development of the disease. Other studies have classified the behavior of this protein in different pathologies, including Alzheimer's disease (AD) and cardiovascular disease. The general behavior of the epsilon4 isoform of ApoE is different than the predominant epsilon3 isoform.

HYPOTHESIS

We propose that the general characteristics and molecular behavior of apoE epsilon4 cause it to be a protective factor against the development of ARMD by preventing cumulative effects of oxidative retinal damage. EVALUATION OF HYPOTHESIS: Review of the literature related to ARMD and ApoE, using OVID as our main database, led to the development of several theories regarding ApoE epsilon4's behavior compared to epsilon3 and potential explanation of its protective characteristics. CONSEQUENCES OF HYPOTHESIS: We relate these theories to the potential behavior of ApoE epsilon4 in other situations including choroidal neovascularization, Alzheimer's Disease (AD), cardiovascular disease, herpes simplex virus infection, and smoking.

DISCUSSION

The potential implications of this theory could be used as a branching point for further studies that examine the role of the different apoE isoforms, in relation to the other risk factors for ARMD.

[Stress-protective effect of the synthetic ACTH-like peptide leucocorticotropin]

We found that the tritium-labeled synthetic ACTH-like octapeptide leucocorticotropin corresponding to the 81-88 sequence of the precursor of human interleukin-1alpha ([3H]GKVLKKRR) is bound by the ACTH receptor of rat adrenal cortex with a high affinity and specificity (Kd 2.2 +/- 0.1 nM). This peptide was shown to exert no effect on the adenylate cyclase activity of the membranes of rat adrenal cortex in the concentration range from 1 to 1000 nM. Leucocorticotropin administration three times at doses of 10-20 microg/animal did not change the level of hydroxycorticosteroids (11-HOCS) in the rat adrenal glands in the absence of temperature action. At the same time, the peptide abolishes (at a dose of 20 microg/animal, three times) or significantly decreases (at a dose of 10 microg/animal, three times) the dramatic increase in the 11-HOCS content in the adrenal glands occurring in the case of cold or heat shock. Thus, leucocorticotropin normalizes the 11-HOCS level in the rat adrenal cortex during stress. The stress-protective effect of the peptide is mediated through the ACTH receptor.

Antioxidants protect PINK1-dependent dopaminergic neurons in Drosophila

Parkinson's disease (PD) is the most frequent neurodegenerative movement disorder. Mutations in the PINK1 gene are linked to the autosomal recessive early onset familial form of PD. The physiological function of PINK1 and pathological abnormality of PD-associated PINK1 mutants are largely unknown. We here show that inactivation of Drosophila PINK1 (dPINK1) using RNAi results in progressive loss of dopaminergic neurons and in ommatidial degeneration of the compound eye, which is rescued by expression of human PINK1 (hPINK1). Expression of human SOD1 suppresses neurodegeneration induced by dPINK1 inactivation. Moreover, treatment of dPINK1 RNAi flies with the antioxidants SOD and vitamin E significantly inhibits ommatidial degeneration. Thus, dPINK1 plays an essential role in maintaining neuronal survival by preventing neurons from undergoing oxidative stress, thereby suggesting a potential mechanism by which a reduction in PINK1 function leads to PD-associated neurodegeneration.

The neuropeptide FMRFamide can protect cells against apoptosis in the snail digestive gland

FMRFamide-related peptides are widespread neurotransmitters or neurohormones regulating somatic or visceral motor activity. Some recent data indicate that these neuropeptides may be involved in the control of cell proliferation and apoptosis. In this work we investigated the possible effect of FMRFamide on cell viability in an invertebrate-type proliferating tissue. As a model, we used the midintestinal gland of the snail, Helix lucorum Linnaeus. Immunohistochemistry demonstrated the direct innervation of the gland cells by FMRFamide-containing nerve fibers. Midintestinal glands of snails were injected with 50 microM FMRFamide and the control with sterile deionised water or bovine serum albumin (BSA). Injections were administrated 4 times. Transmission electron microscopy, annexin V-labeling, thiazolyl blue (MTT) viability tests and ploidy analyses were carried out to define the viable/dead cell ratio in the tissue samples. FMRFamide increased the MTT-reduction of tissues, reduced the amount of apoptotic nuclei and annexin V-labeled cells. Deionised water or BSA injection induced cell death. Cell cycle analysis revealed that FMRFamide significantly elevated the amount of cells in G0/G1 phase, but did not induce mitosis. We conclude, that the FMRFamide can be a life-signal for cells, protect them from apoptosis without altering mitosis.

Lipid peroxidation as a source of oxidative damage in Helicobacter pylori: protective roles of peroxiredoxins

Oxidative stress conditions lead to enzymatic and non-enzymatic unsaturated fatty acid-initiated lipid peroxidation reactions. One exacerbating product is lipid hydroperoxide (LOOH) which itself promotes formation of several additional peroxyl radicals. Helicobacter pylori mutant strains with disruptions in genes encoding the peroxiredoxins, alkyl hydroperoxide reductase (ahpC) and the bacterioferritin comigratory protein (bcp), were more sensitive than the parent strain to oxidizing agents. These mutant strains were particularly sensitive, compared to the wild type, to killing by the unsaturated fatty acid linolenic acid but were not sensitive to the saturated fatty acid palmitic acid. A double mutant strain (ahpC bcp) accumulated more than 3-fold more lipid peroxides than the parent strain, indicating these peroxiredoxins together play a role in detoxifying lipid peroxides. The level of free iron accumulation, a signature of oxidative stress damage, was correlated specifically to organic peroxide-mediated stress by both in vivo and in vitro approaches. Free iron accumulation and concomitant destruction of [Fe-S] cluster-containing proteins (hydrogenase and aconitase) was correlated to damage mediated by exogenous t-butyl peroxide, or separately to intracellular accumulation of lipid peroxides in mutant strains. A major macromolecular target of accumulating lipid peroxides in H. pylori is DNA, as mutant analysis approaches combined with quantitative DNA fragmentation studies and specific DNA damage assessment (i.e. 8-oxoguanine formation) were used to demonstrate that such damage was especially associated with ahpC and ahpC bcp strains.

[Physiological metabolism and protective enzyme activity of Equisetum ramosissimum under Cu stress]

The study with pot culture experiment showed that Equisetum ramosissirmunm did not appear obvious poisoning symptoms when treated with low concentration Cu (500 mg x kg(-1)), while serious injuries were found when treated with high concentration Cu (1000 to approximately 3000 mg x kg(-1)), which reflected in the severe damage of cell membrane and cytoarchitecture as well as the structure and function of main organelles, and the significant decrease of the contents of leaf chlorophyll a and b and stem soluble monosaccharose. The cell membrane osmolarity and the average MDA content of the plant exposed to heavy copper pollution was 1 to approximately 2 and 1 to approximately 3 times greater than the control, respectively. It could be concluded that high concentration Cu disturbed the physiological metabolism, and critically threatened the normal growth of E. ramosissimum. The activities of protective enzyme, especially of SOD and POD, were enhanced with increasing Cu concentration, and had a positive correlation with Cu concentration (rPOD = 0.978, rSOD = 0.926, P < 0.05).

Protective effects of calcium-magnesium soft gels in morphine tolerant and dependent mice

The present study was aimed at evaluating the acute effects of Calcium-Magnesium soft gels (CalMag) in morphine tolerant and dependent mice. Mice were rendered tolerant and dependent on morphine by subcutaneous injection of morphine over a fixed time period. Withdrawal signs were precipitated by injecting naloxone 2 h after the final injection of morphine. The tail-pinch assay was used to investigate the effects of various compounds on the development and reversal of morphine tolerance. Acute injection of CalMag (containing 50 mg/kg calcium and 25 mg/kg magnesium) significantly reduced the number of jumps, stands and fast breathing in morphine dependent mice. Co-administration of calcium (50 mg/kg) and magnesium (25 mg/kg) was also effective in preventing the development of morphine tolerance and dependence. Administration of calcium (up to 50 mg/kg) alone did not significantly block the development of tolerance and dependence. The mean latency to pain was significantly increased in animals pretreated with CalMag (containing 50 mg/kg calcium and 25 mg/kg magnesium). The mixture of calcium and magnesium at specific concentrations seem to be critical for preventing the development of morphine tolerance and dependence.

Protective effect of dietary capsaicin on induced oxidation of low-density lipoprotein in rats

An animal study was carried out to examine the beneficial influence of the known hypocholesterolemic spice principle-capsaicin on the susceptibility of low-density lipoprotein to oxidation in normal and hypercholesterolemic condition. In rats rendered hypercholeterolemic by maintaining them on a cholesterol-enriched diet for eight weeks, inclusion of capsaicin (0.015%) in the diet, produced significant hypocholesterolemic effect. Oxidation of low-density lipoprotein was induced either by copper ion in vitro after its isolation, or by ferrous ion in vivo in experimental rats under either normal or hypercholesterolemic situation and the beneficial effect of dietary capsaicin on the same was evaluated. LDL oxidation was measured by the thiobarbituric acid reactive substances (TBARS) formed and relative electrophoretic mobility of oxidized LDL. Dietary capsaicin was found to be protective to the LDL oxidation in vitro in the case of normal rats as indicated by reduction in TBARS by more than 40%. In the case of LDL isolated from hypercholesterolemic rats the extent of copper induced LDL oxidation was significantly lower than that of LDL isolated from normal rats. Dietary capsaicin did not make any difference in the extent of LDL oxidation in vitro in hypercholesterolemic rats. Ferrous ion induced in vivo oxidation of LDL was 71% lower in capsaicin fed normal rats. In high cholesterol feeding, Fe-induced in vivo oxidation of LDL was 73% lower, while the same was still marginally lower in capsaicin fed hypercholesterolemic rats. Hepatic lipid peroxidation was significantly decreased by dietary capsaicin in normal rats. While a significantly decreased level of lipid peroxidation was observed in hypercholesterolemic rats compared to normal rats, the same was not significantly altered by dietary capsaicin. Results suggest that dietary spice principle capsaicin is protective to LDL oxidation both in vivo and in vitro under normal situation, while in hypercholesterolemic situation where the extent of LDL oxidation is already lowered, capsaicin does not offer any further reduction.

Potential protective action of pituitary adenylate cyclase-activating polypeptide (PACAP38) on in vitro and in vivo models of myeloma kidney injury

The most common type of renal injury in multiple myeloma is chronic tubulointerstitial nephropathy associated with casts in tubule lumens, an entity referred to as “myeloma kidney” that often progresses to end-stage kidney diseases. Myeloma kidney is associated with a significant increase in all-cause mortality, yet no effective intervention, except a limited use of steroid, is available. Here, we report that pituitary adenylate cyclase-activating polypeptide with 38 residues (PACAP38) dramatically prevents injury of cultured renal proximal tubule cells caused by myeloma light chains through suppression of proinflammatory cytokines production, by inhibiting p38 MAPK and translocation of NFκB via both PAC1 and VPAC1 receptors. The suppressive effects of PACAP was as effective as dexamethasone in all of their cytokine assays and demonstrated both in vitro and in vivo. Furthermore, PACAP38 inhibits myeloma cell growth directly and may also indirectly by suppressing production of the growth factor, IL-6, from bone marrow stromal cells, that is stimulated by adhesion of myeloma cells. These findings render PACAP38 worth evaluation as a promising candidate for an effective and safe renoprotectant in myeloma kidney, and possibly other nephropathy, and also as a new antitumor agent in multiple myeloma.

Adaptive response induced by lipid peroxidation products in cell cultures

The adaptive response induced by the lipid peroxidation products, such as phosphatidylcholine hydroperoxide, lysophosphatidylcholine (LysoPC), 15-deoxy-Delta(12,14)-prostaglandin J(2), 4-hydroxynonenal (4-HNE), hydroxyoctadecadienoic acid, 7-hydroxycholesterol, and cholesterol 5beta,6beta-epoxide, was investigated in this study. Although these products have been implicated in oxidative stress-related diseases, pretreatment with such compounds at sublethal concentrations significantly protected PC12 cells against subsequent oxidative stress induced by 6-hydroxydopamine. Moreover, 4-HNE and LysoPC also exhibited adaptive protection in human arterial endothelial cells. These findings suggest a general hormetic effect of such compounds in cell cultures and may lead to a reappraisal of the eventual role of reactive oxygen species and lipid peroxidation in organisms.

[Effects of water stress on protective enzyme activities and lipid peroxidation in Phellodendron amurense seedlings]

This paper studied the effects of water stress on the dynamic variations of malondialdehyde (MDA) and free proline contents, and of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities in Phellodendron amurense seedlings. The results showed that after treated with light drought, heavy drought and waterlogging for 40 days, the MDA content in corktree seedlings was significantly higher, being 2.49, 2.37 and 4.12 times of the control, respectively, but after treated for 80 days, there was no significant difference among the three treatments. The free proline content had no obvious variation under waterlogging and in the control, but increased after 40 days of light and heavy drought while declined after 80 days of drought stresses, with the increment being higher under heavy drought than under light drought. No regularity was found for the dynamic variations of SOD, POD and CAT activities, but they were significantly higher under heavy drought than under light drought, waterlogging, and the control.

Endogenous hydrogen sulfide contributes to the cardioprotection by metabolic inhibition preconditioning in the rat ventricular myocytes

The possible role of hydrogen sulfide (H2S) in cardioprotection was investigated in isolated rat ventricular myocytes exposed to severe metabolic inhibition (MI) in glucose-free buffer containing 2-deoxy-D-glucose (2-DOG), an inhibitor of glycolysis. Pretreatment (30 min) with NaHS (a H2S donor) at concentrations of 10(-5) to 10(-4) mol/L caused a concentration related increase in cell viability and the ratio of rod-shaped cells. A time course study showed that NaHS-induced cardioprotection occurred in 2 time windows (approximately 1 h and 16-28 h). To observe whether endogenous H2S may be involved in the delayed cardioprotection response of IP, DL-propargylglycine (PAG) and beta-cyano-L-alanine (BCA; two inhibitors of H2S biosynthesis) were used. Both drugs significantly attenuated the cardioprotection produced by MI using cell viability, cellular injury index, and electrically-induced [Ca2+]i transients as end-points. These data suggest that endogenous H2S plays an important role in the cardioprotection following MI preconditioning. In an attempt to determine the mechanism of the cardioprotective effect of H2S, we examined the effect of blocking KATP channels with glibenclamide (a non-selective KATP channel blocker), 5-hydroxydecanoic acid (5-HD, a mitochondrial KATP blocker), and HMR-1098 (a sarcolemmal KATP blocker). The cardioprotective effects of NaHS were significantly attenuated by glibenclamide and HMR-1098 treatment but not by 5-HD. Inhibition of NO production with L-NG nitroarginine methyl ester (L-NAME) also attenuated the cardioprotection of NaHS. In conclusion, our findings provide the first evidence that H2S may protect the heart most probably by activating sarcolemmal KATP channels and/or provoking NO release and the cardioprotective effects of metabolic ischemic preconditioning is, at least partially, mediated by endogenous H2S.

Hepatoprotective effects of Nigella sativa L and Urtica dioica L on lipid peroxidation, antioxidant enzyme systems and liver enzymes in carbon tetrachloride-treated rats

AIM: To investigate the effects of Nigella sativa L (NS) and Urtica dioica L (UD) on lipid peroxidation, antioxidant enzyme systems and liver enzymes in CCl₄-treated rats.

METHODS: Fifty-six healthy male Wistar albino rats were used in this study. The rats were randomly allotted into one of the four experimental groups: A (CCl₄-only treated), B (CCl₄+UD treated), C (CCl₄+NS treated) and D (CCl₄+UD+NS treated), each containing 14 animals. All groups received CCl₄ (0.8 mL/kg of body weight, sc, twice a week for 60 d). In addition, B, C and D groups also received daily i.p. injections of 0.2 mL/kg NS or/and 2 mL/kg UD oils for 60 d. Group A, on the other hand, received only 2 mL/kg normal saline solution for 60 d. Blood samples for the biochemical analysis were taken by cardiac puncture from randomly chosen-seven rats in each treatment group at beginning and on the 60^th d of the experiment.

RESULTS: The CCl₄ treatment for 60 d increased the lipid peroxidation and liver enzymes, and also decreased the antioxidant enzyme levels. NS or UD treatment (alone or combination) for 60 d decreased the elevated lipid peroxidation and liver enzyme levels and also increased the reduced antioxidant enzyme levels. The weight of rats decreased in group A, and increased in groups B, C and D.

CONCLUSION: NS and UD decrease the lipid per-oxidation and liver enzymes, and increase the anti-oxidant defense system activity in the CCl₄-treated rats.

Pioglitazone, a specific ligand of peroxisome proliferator-activated receptor-gamma, protects pancreas against acute cerulein-induced pancreatitis

AIM: To determine the effect of pioglitazone, a specific peroxisome proliferator-activated receptor-γ (PPARγ) ligand, on the development of acute pancreatitis (AP) and on the expression of heat shock protein 70 (HSP70) in the pancreas.

METHODS: AP was induced in rats by subcutaneous infusion of cerulein for 5 h. Pancreatic blood flow was measured by laser Doppler flowmetry. Plasma lipase activity, interleukin-1β (IL-1β) and IL-10 were determined. Pancreatic weight and histology were evaluated and pancreatic DNA synthesis and blood flow as well as pancreatic mRNA for IL-1β and HSP70 were assessed in rats treated with pioglitazone alone or in combination with cerulein.

RESULTS: Pioglitazone administered (10-100 mg/kg i.g.) 30 min before cerulein, attenuated dose-dependently the pancreatic tissue damage in cerulein-induced pancreatitis (CIP) as demonstrated by the improvement of pancreatic histology, reduction in plasma lipase activity, plasma concentration of pro-inflammatory IL-1β and its gene expression in the pancreas and attenuation of the pancreatitis-evoked fall in pancreatic blood flow. CIP increased pancreatic HSP70 mRNA and protein expression in the pancreas and this effect was enhanced by pioglitazone treatment.

CONCLUSION: Pioglitazone attenuates CIP and the beneficial effect of this pioglitazone is multifactorial probably due to its anti-inflammatory activities, to the suppression of IL-1β and to the overexpression of HSP70. PPARγ ligands could represent a new therapeutic option in the treatment of AP.

Protective effect of selenium-enriched lactobacillus on CCl4-induced liver injury in mice and its possible mechanisms

AIM: To study the protective effects and mechanisms of Se-enriched lactobacillus on liver injury caused by carbon tetrachloride (CCl₄) in mice.

METHODS: Seventy-two ICR mice were randomly divided into four groups: normal group, CCl₄-induced model group, low Se-enriched lactobacillus treatment group (L-Se group), and high Se-enriched lactobacillus treatment group (H-Se group). During a 3-wk experimental period, the common complete diet was orally provided daily for normal group and model group, and the mice in L-Se and H-Se groups were given a diet with 2 and 4 mg of organoselenium from Se-enriched lactobacillus per kg feed, respectively. From the 2nd wk of experiment, the model group, L-Se group, and H-Se group received abdominal cavity injection of olive oil solution containing 500 mL/L CCl₄ (0.07 mL/100 g body mass) to induce liver injury, and the normal group was given olive oil on every other day for over 2 wk. In the first 2 wk post injection with CCl₄, mice in each group were killed. The specimens of blood, liver tissue, and macrophages in abdominal cavity fluid were taken. Then the activities of the following liver tissue injury-associated enzymes including glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) as well as malondialdehyde (MDA) content were assayed. Changes of phagocytic rate and phagocytic index in macrophages were observed with Wright-Giemsa stain. Plasma TNF-α level was measured by radioimmunoassay. The level of intracellular free Ca²⁺ ([Ca²⁺]i) in hepatocytes was detected under a laser scanning confocal microscope.

RESULTS: During the entire experimental period, the AST and ALT activities in liver were greatly enhanced by CCl₄ and completely blunted by both low and high doses of Se-enriched lactobacillus. The Se-enriched lactobacillus-protected liver homogenate GSH-Px and SOD activities were higher or significantly higher than those in model group and were close to those in normal group. CCl₄ significantly increased MDA content in liver homogenates, while administration of Se-enriched lactobacillus prevented MDA elevation. Phagocytic rate and phagocytic index of macro-phages decreased after CCl₄ treatment compared to those in normal control, but they were dramatically rescued by Se-enriched lactobacillus, showing a greatly higher phagocytic function compared to model group. CCl₄ could significantly elevate plasma TNF-α and hepatocyte [Ca²⁺]ilevel, which were also obviously prevented by Se-enriched lactobacillus.

CONCLUSION: Se-enriched lactobacillus can intervene in CCl₄-induced liver injury in mice by enhancing macrophage function activity to keep normal and beneficial effects, elevating antioxidant-enzyme activities and reducing lipid peroxidation reaction, inhibiting excessive release of TNF-α, preventing the dramatic elevation of [Ca²⁺]i in hepatocytes.

Heparin-binding EGF-like growth factor (HB-EGF) and necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a common and devastating gastrointestinal disease that occurs predominantly in premature infants. Despite various advances in management, the mortality of this disease remains high. During the last decade, studies from our laboratory have shown that heparin-binding epidermal growth factor-like growth factor (HB-EGF), a member of the epidermal growth factor (EGF) family, can protect intestinal epithelial cells (IEC) from various forms of injury in vitro. Furthermore, we have used both an intestinal I/R injury model in adult rats, and a neonatal rat pup model of NEC, to show that HB-EGF can protect the intestines from injury. On administration of HB-EGF in the neonatal rat model, the incidence of NEC is reduced from 65% to 27.3% (P < 0.05), and the histological injury score is decreased from 2 to 1.1 (P < 0.05). In addition, the survival rate is increased from 25% to 63.6% and the survival time extended from 59 hours to 73 hours (P < 0.05). In addition, using human specimens from newborns undergoing bowel resection for NEC, we found that the expression of endogenous HB-EGF mRNA in normal areas of the intestine at the resection margins was higher than that of the intestine afflicted with acute NEC. Endogenous HB-EGF may be involved in epithelial cell repair, proliferation, and regeneration during recovery from injury. Exogenous administration of HB-EGF potentiates recovery from intestinal injury in vitro and in vivo. Taken together, these results support a potential therapeutic role for HB-EGF in the treatment of NEC in the future.

Expression of taurine transporter is regulated through the TonE (tonicity-responsive element)/TonEBP (TonE-binding protein) pathway and contributes to cytoprotection in HepG2 cells

In hypertonic environment, taurine accumulates in cells via activation of TauT (taurine transporter) as an adaptive regulation. Recent studies revealed that TonE (tonicity-responsive element)/TonEBP (TonE-binding protein) pathway regulated the expression of various molecules which protect cells against hypertonic stress. In the present study, we investigated the osmoregulatory mechanisms of TauT expression. TauT was up-regulated at both functional and transcriptional levels in HepG2 under hypertonic condition. The TonE site was identified in the promoter region of TauT gene. Reporter gene assay revealed that promoter activity was increased under hypertonic conditions, whereas deletion or mutation of TonE sequence abolished the induction of the promoter activity in response to hypertonicity. By using the reporter gene plasmids containing a TonE site of TauT promoter (p2xTonE-Luc), it was demonstrated that a TonE site was sufficient for the hypertonicity-mediated activation of TauT promoter. Importantly, co-transfection of TauT promoter gene plasmid with wild-type TonEBP expression vector enhanced promoter activity under isotonic conditions, whereas dominant-negative TonEBP abrogated the TauT promoter activity induced by hypertonicity. Finally, treatment with taurine prevented HepG2 cells from cell death induced by hypertonic medium. These findings suggested that induction of TauT by hypertonicity is mediated by the activation of the TonE/TonEBP pathway and confers resistance to hypertonic stress.

Does Proteosome Inhibition Decrease or Accelerate Toxin-Induced Dopaminergic Neurodegeneration?

Parkinson's disease (PD) is pathologically characterized by dopaminergic (DA) cell death and the presence of Lewy bodies (LB) in the brain. alpha-Synuclein (alpha-syn) and ubiquitin (Ub) are the major components of LB, however, the process of their accumulation and their relationship to DA cell loss has not yet been resolved. Now, in this journal, Inden et al. showed the protective effect of proteasome inhibitors (PSI) on DA cell death in the rat PD model using 6-hydroxyl dopamine (6-OHDA). Co-administration of PSI, lactacystin, or MG-132 significantly prevented the nigral degeneration and apomorphine-induced rotational asymmetry of the model with increased appearance of alpha-syn- and Ub-positive inclusions in the substantia nigra. This study indicates that in their model, accelerated formation of inclusions via proteasome inhibition protects against DA cell death. Previous literature linked the impairments or inhibitions of the ubiquitin-proteasome system (UPS) and DA cell death. However, this report implies that the relationship between the UPS and the pathogenesis of PD may be more complex than we thought.

Protective role of heme oxygenase-1 in renal ischemia

Oxidative stress, which has been implicated in the pathogenesis of ischemic renal injury, degrades heme proteins, such as cytochrome P450, and causes the elevation in the level of cellular free heme, which can catalyze the formation of reactive oxygen species. Heme oxygenase-1 (HO-1), the rate-limiting enzyme in heme degradation, is induced not only by its substrate, heme, but also by oxidative stress. In various models of oxidative tissue injuries, the induction of HO-1 confers protection on tissues from further damages by removing the prooxidant heme, or by virtue of the antioxidative, antiinflammatory, and/or antiapoptotic actions of one or more of the three products, i.e., carbon monoxide, biliverdin IXalpha, and iron by HO reaction. In contrast, the abrogation of HO-1 induction, or chemical inhibition of HO activity, abolishes its beneficial effect on the protection of tissues from oxidative damages. In this article, we review the protective role of HO-1 in renal ischemic injury, and its potential therapeutic applications. In addition, we summarize recent findings in the regulatory mechanism of ho-1 gene expression.

Possible (enzymatic) routes and biological sites for metabolic reduction of BNP7787, a new protector against cisplatin-induced side-effects

Disodium 2,2'-dithio-bis-ethane sulfonate (BNP7787) is under investigation as a potential new chemoprotector against cisplatin-induced nephrotoxicity. The selective protection of BNP7787 appears to arise from the preferential uptake of the drug in the kidneys, where BNP7787 would undergo intracellular conversion into mesna (2-mercapto ethane sulfonate), which in turn can prevent cisplatin induced toxicities. In the present study, we have investigated whether the reduction of BNP7787 into the reactive compound mesna is restricted to the kidney or whether it can also occur in other organs, cells and physiological compartments, including the cytosolic fraction of the renal cortex, plasma, red blood cells (RBCs), liver and small intestine from rats and several tumors (OVCAR-3, MRI-H-207 and WARD). We also determined whether the endogenous thiols glutathione (GSH) and cysteine and the enzyme systems glutaredoxin and thioredoxin, which are all present in the kidney, can be involved in the BNP7787 reduction. UV detection and micro-HPLC with dual electrochemical detection were used to analyze the various incubation mixtures. Our observations are that, in contrast to plasma, a very large reductive conversion of BNP7787 to mesna was measured in RBC lysate. Intact RBCs, however, did not take up BNP7787. Although BNP7787 could be reduced in cytosol of liver and several tumors, this reduction will not be relevant in vivo, since these tissues do not take up large amounts of BNP7787. Kidney cortex cytosol was, similar to the small intestine cytosol, able to substantially reduce BNP7787 to mesna. The ability to reduce BNP7787 in the presence of the endogenous thiols GSH and cysteine, the glutaredoxin system as well as the thioredoxin system, could at least in part explain the high BNP7787 reductive activity of the kidney cortex cytosol. In conclusion, the high reduction of BNP7787 into mesna in the kidney as well as our earlier observation that the distribution of BNP7787 and mesna was mainly restricted to rat kidney are strong arguments in favor of selective protection of the kidney by BNP7787.

Hypoxia-induced nitric oxide protects chondrocytes from damage by hydrogen peroxide

OBJECTIVE

Because articular cartilage has no vascular supply, chondrocytes are hypoxic under normal physiological conditions. Nitric oxide (NO) plays an important role in chondrocyte damage, such as apoptosis. Although oxygen stress with hydrogen peroxide was found to cause chondrocyte damage, these data were obtained under normoxic (21% O2) conditions. We investigated the effects of hypoxia on hydrogen peroxide-induced chondrocyte damage

METHODS

Bovine articular chondrocytes were used in this study. Proteoglycan (PG) synthesis and the induction of apoptosis were analyzed with [(35)S]-sulfate incorporation and annexin V staining, respectively. The induction of NO was examined using a fluorescent probe and RT-PCR.

RESULTS

Cells maintained at 5% O2 had the maximum PG synthesis. Under normoxic conditions, hydrogen peroxide inhibited PG synthesis and induced annexin V positive cells in a dose-dependent fashion. However, in those cells cultured under hypoxic (5%) conditions, the hydrogen peroxide-induced annexin V expression was attenuated. Chondrocytes exposed to hypoxia showed induction of NO. When the hypoxia-induced NO was inhibited, the hypoxia-enhanced PG synthesis was abolished and hydrogen peroxide clearly induced cell damage.

CONCLUSIONS

Endogenous NO induced by hypoxia protects chondrocytes from apoptosis induced by an oxidative stress.

The protective effects of HDL and its constitutents against neutrophil respiratory burst activation by hypochlorite-oxidized LDL

Hypochlorite-oxidized low-density lipoprotein (oxLDL) possesses a substantial proinflammatory potential by modulating respiratory burst activities of polymorphonuclear neutrophils (PMN). As evaluated by luminol-amplified chemiluminescence (CL) incubation of 10(6) PMN/ml with 70 nM oxLDL was followed by substantial induction of neutrophil oxidant (ROS) generation. We evaluated the inhibitory capacity of high-density lipoprotein (HDL) and its lipid and protein constituents against the activating effects of oxLDL. At a HDL or apolipoprotein AI/LDL protein ratio of 1.0, native HDL decreased the respiratory burst activation by 64%, followed by trypsinized HDL (57%) and native apoAI (43%). The inhibitory effects of native HDL did not require prior incubation with PMN or with oxLDL suggesting an instantaneously acting protective mechanism in the minute range. OxLDL modulated ROS production not only of resting PMN but also that of activated PMN, as indicated by a 14-fold increase in FMLP-stimulated CL response and a 50% decrease in zymosan-mediated CL answer. HDL itself did not protect PMN from activation by FMLP and zymosan. However, it clearly reduced effects of oxLDL on FMLP-activation and slightly counteracted the oxLDL-mediated decrease in zymosan-induced ROS generation. Taken together, these findings may offer new insight into atheroprotective mechanisms of HDL.