Regulation of collagen synthesis by ascorbic acid: characterization of the role of ascorbate-stimulated lipid peroxidation

In Vitro Evaluation of the Effect of a Not Cross-Linked Hyaluronic Acid Hydrogel on Human Keratinocytes for Mesotherapy

The multicomponent preparations for mesotherapy are based on the principle that skin and hair aging can be prevented by supplying the fundamental substrates for correct cellular functioning, such as nucleotides, vitamins, amino acids, and biomolecules including hyaluronic acid (HA) that promote skin hydration and several biological activities. The study provides evidence for the application of HYDRO DELUXE BIO (Matex Lab S.p.A), a biocompatible hydrogel containing not cross-linked HA, for the treatment of the scalp’s skin by mesotherapy. Using an in vitro model of immortalized human keratinocytes, we studied markers involved in hair aging prevention and growth, such as inflammatory markers, angiogenesis, and oxidative damage. HYDRO DELUXE BIO showed high biocompatibility and the ability to significantly reduce the expression of the inflammation marker interleukin (IL)-8 in Tumor Necrosis Factor (TNF)-stimulated cells. Then, we evaluated angiogenesis, a pivotal event during hair growth, measuring the Vascular Endothelial Growth Factor (VEGF) expression that resulted to be significantly increased in treated cells, suggesting a pro-angiogenetic capability. A protective activity against the oxidative stress agent was showed, increasing the survival rate in treated cells. Concluding, HYDRO DELUXE BIO is suitable for treatment by mesotherapy of the scalp’s skin as it modulates the expression levels of markers involved in the biorevitalization of the hair follicle.

Reprogramming the Epigenome With Vitamin C

The erasure of epigenetic modifications across the genome of somatic cells is an essential requirement during their reprogramming into induced pluripotent stem cells (iPSCs). Vitamin C plays a pivotal role in remodeling the epigenome by enhancing the activity of Jumonji-C domain-containing histone demethylases (JHDMs) and the ten-eleven translocation (TET) proteins. By maintaining differentiation plasticity in culture, vitamin C also improves the quality of tissue specific stem cells derived from iPSCs that are highly sought after for use in regenerative medicine. The ability of vitamin C to potentiate the activity of histone and DNA demethylating enzymes also has clinical application in the treatment of cancer. Vitamin C deficiency has been widely reported in cancer patients and has recently been shown to accelerate cancer progression in disease models. Therapies involving high-dose vitamin C administration are currently gaining traction in the treatment of epigenetic dysregulation, by targeting aberrant histone and DNA methylation patterns associated with cancer progression.

Determining the effectiveness of vitamin C in skin care by atomic force microscope

This article presents the results of experiments, which examine cell mechanisms with the goal of confirming the effective action of the active ingredients used in anti-aging cosmetics. Skin stiffness measurements with the use of an atomic force microscope on two forms of vitamin C (ascorbyl tetraisopalmitate and l-ascorbic acid) have been presented. The estimated Young's modulus for three types of cells (a control as well as cells treated with two forms of vitamin C) has shown significant differences in the stiffness of the tested cells which was confirmed in the histological staining experiment. The presented results indicate the dependence between collagen synthesis and the stiffness of cells treated with two forms of vitamin C.

Effects of 3 Rodent Beddings on Biochemical Measures in Rats and Mice

Components of bedding might interact with experimental treatments and affect the outcome of various experiments. Here we studied the biochemical effects of 3 rodent bedding materials that are commonly used in Egypt. Male and female rats and mice were assigned randomly into 4 single-sex and single-species groups (10 animals per group). Three types of bedding-rice straw, wheat straw, and pine wood shavings-were evaluated. After 4 wk, animals were euthanized, and biochemical parameters were measured. In male and female rats given wood shavings, serum ALT activity and malondialdehyde concentration increased whereas catalase activity decreased compared with levels in the wheat straw group. In contrast, ALT activity and malondialdehyde concentrations decreased but CAT activity increased in rats housed on rice straw compared with wheat straw. Serum AST and ALT activities increased in male and female mice exposed to rice straw, whereas the malondialdehyde concentration increased and catalase decreased in the wood shavings group relative to the wheat straw group. In mice exposed to wheat straw, AST and ALT activities and malondialdehyde concentrations decreased and CAT activity increased compared with the other groups. Because our results showed that exposure to wood shavings affects some biochemical parameters of rats and mice, we do not recommend its use as laboratory animal bedding. We consider that, of the materials tested, rice straw bedding is the best bedding material for rats, whereas wheat straw is best for mice.

Correlation of Clinical and Histopathological Grades in Oral Submucous Fibrosis Patients with Oxidative Stress Markers in Saliva

This study aimed to correlate the oxidative stress marker levels in saliva with the clinical stage based on mouth opening, fibrotic bands and histopathological grades of oral submucous fibrosis (OSF) patients. The study included patients clinically diagnosed with OSF (n = 63) and equal number of age and gender matched controls. Patients with OSF were defined by mouth opening stage, fibrotic bands and histopathological grades. Unstimulated saliva from both control and OSF patients were analysed for oxidative markers like lipid peroxides (LPO), non-enzymic antioxidants [reduced glutathione (GSH), vitamin A, vitamin E, vitamin C] and enzymatic antioxidants [glutathione peroxidase (GPx), superoxide dismutase (SOD)] and correlated with different stages and grades. Total salivary protein and LPO were significantly increased in OSF group with no significant change in the levels of GSH compared to controls. In OSF patients, a significant decrease in the levels of vitamins A, C and E was observed. The activities of salivary SOD and GPx were significantly decreased in OSF patients compared to controls. These changes significantly correlated with the increasing and differing grades of OSF that reflects increased oxidative stress with the progress of OSF.

Glutamine inhibits CCl4 induced liver fibrosis in mice and TGF-β1 mediated epithelial-mesenchymal transition in mouse hepatocytes

Glutamine, traditionally a non-essential amino acid, now has been considered as essential in serious illness and injury. It is a major precursor for glutathione synthesis. However, the anti-fibrotic effect of glutamine and its molecular mechanism in experimental liver fibrosis have not been explored. In the present study we aimed to examine the potential role of glutamine in carbon tetrachloride (CCl4) induced liver fibrosis and TGF-β1 mediated epithelial mesenchymal transition (EMT) and apoptosis in mouse hepatocytes. Liver fibrosis was induced by intraperitoneal injection of CCl4 three times a week for 10 weeks. Glutamine treatment effectively attenuated liver injury and oxidative stress. Collagen content was significantly decreased in liver sections of glutamine treated mice compared to CCl4 model mice. Furthermore, glutamine decreased expression level of α-SMA and TGF-β in liver tissue. Our in vitro study showed that TGF-β1 treatment in hepatocytes resulted in loss of E-cadherin and increased expression of mesenchymal markers and EMT related transcription factor. In addition, TGF-β1 increased the expression of apoptotic markers. However, glutamine interestingly suppressed TGF-β1 mediated EMT and apoptosis. In conclusion, our results suggest that glutamine ameliorates CCl4 induced liver fibrosis and suppresses TGF-β1 induced EMT progression and apoptosis.

Prophylactic effect of aqueous extract of Sesamum indicum seeds on ethanol-induced toxicity in male rats

The liver is vulnerable to alcohol-related injury because it is the primary site of alcohol metabolism. Additionally, a number of potentially dangerous by-products are generated as alcohol is broken down in the liver. However, dietary supplements may prevent or relieve some of alcohol's deleterious effects. Therefore, this study was conducted to evaluate the prophylactic effect of aqueous extract of Sesamum indicum (SI) on ethanol induced toxicity in rats. Male Wistar albino rats were divided into control, ethanol, pre-treatment, simultaneous and post-treatment groups. In the prophylactic experiment, Sesamum indicum, (200 mg/kg body weight) was administered by oral gavage for 28 days; two hours before, simultaneously with or two hours after ethanol exposure. Toxicity was induced by administering 45% ethanol (4.8 g/kg bw) by oral gavage. Lipid peroxidation (TBARS) and reduced glutathione (GSH) levels and catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD) and gluthathione-S-transferase (GST) activities were then determined in the liver, serum triglyceride (TG) levels, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities were monitored and histological examination was carried out. The results revealed that ethanol administration led to significant elevation of TBARS level while depleting in the level of GSH as well as CAT, GPx, SOD and GST activities. Similarly, TG level and ALT and AST activities were elevated. The SI pre-treated group significantly inhibited TBARS, restored GSH level, enhanced CAT, GPx, SOD and GST activities and significantly decreased the elevated level of serum TG, ALT and AST activities. SI treatment (simultaneously with ethanol) exhibited similar effects to those of the SI pre-treated groups, while the SI post-treated group did not show the same protection as the Pre-treated group. S. indicum possesses antioxidant and hepatoprotective properties, that eliminate the deleterious effects of toxic metabolites of ethanol.

A new minimally invasive mesotherapy technique for facial rejuvenation

Introduction

This study describes a pivotal clinical trial of a new minimally invasive mesotherapy technique for facial rejuvenation.

Methods

The authors utilized two formulations: formulation A with hyaluronic acid, vitamins, amino acids, minerals, coenzymes, and antioxidant substances; formulation B with hyaluronic acid and idebenone. Fifty participants were enrolled in the study and divided in two groups. Group 1 (50–65 years) treated with formulation A. Group 2 (35–50 years) treated with formulation B. The groups underwent four sessions of mesotherapy involving multiple injections. Treatment was conducted at 15 day intervals. All participants had pre- and posttreatment photographs. Punch biopsies were taken from randomly selected participants, baseline and after 6 weeks, and stained for interleukin (IL)-6, IL-1β, matrix metalloproteinase (MMP)-1, and collagen 1. Clinical evaluation was based on the Global Aesthetic Scale (GAIS) and on the Wrinkle Severity Rating Scale (WSRS).

Results

The results produced were statistically analyzed and resulted in a significant and long-lasting effect on facial rejuvenation. Evaluation of photographs at 0, 1, and 2 months revealed significant clinical improvement: brightness, texture, and firmness of the skin. The analysis of the GAIS and WSRS scores in the two groups demonstrated statistically significant results after 2 months. The biopsies taken from randomly selected participants at baseline and after 3 months showed a decrease in IL-1β, IL-6, and MMP1, and an increase in collagen 1.

Conclusion

The new minimally invasive mesotherapy technique described can improve the clinical appearance of the skin in different age groups.

Protective effects of aqueous extract of Hammada scoparia against hepatotoxicity induced by ethanol in the rat

Aqueous extract (AE) of Hammada scoparia leaves was chemically characterized and its hepatoprotective activities were investigated in vivo in rat model. Wistar rats were treated daily with 35% ethanol solution (3 g/kg/day) during 4 weeks and fed with basal diet or basal diet containing AE (200 mg/kg/day). Control rats were treated with saline solution and fed with basal diet. The bioactivity of AE against ethanol-induced oxidative stress in rat liver was studied in order to explore its hepatoprotective effects. H. scoparia extract used at 200 mg/kg body weight significantly prevented the effects of ethanol, which induced a hepatic pathological damage and increased the levels of the serum markers of the enzymes such as alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP). Concomitantly, with these changes, this extract also prevented ethanol-induced oxidative stress in the rat liver as evidenced by the decreased lipid peroxidation level, a considerable decrease in the activities of AST, ALT and ALP and restoring the activities of antioxidant enzymes: superoxide dismutase, catalase and glutathione peroxidase. These biochemical changes were consistent with histopathological observations suggesting marked hepatoprotective effect of the AE of H. scoparia.

Bioactive reagents used in mesotherapy for skin rejuvenation in vivo induce diverse physiological processes in human skin fibroblasts in vitro- a pilot study

The promise of mesotherapy is maintenance and/or recovery of a youthful skin with a firm, bright and moisturized texture. Currently applied medications employ microinjections of hyaluronic acid, vitamins, minerals and amino acids into the superficial layer of the skin. However, the molecular and cellular processes underlying mesotherapy are still elusive. Here we analysed the effect of five distinct medication formulas on pivotal parameters involved in skin ageing, that is collagen expression, cell proliferation and morphological changes using normal human skin fibroblast cultures in vitro. Whereas in the presence of hyaluronic acid, NCTF135(®) and NCTF135HA(®) , cell proliferation was comparable to control cultures; however, with higher expression of collagen type-1, matrix metalloproteinase-1 and tissue inhibitor of matrix metalloproteinase-1, addition of Soluvit(®) N and Meso-BK led to apoptosis and/or necrosis of human fibroblasts. The data indicate that bioactive reagents currently applied for skin rejuvenation elicit strikingly divergent physiological processes in human skin fibroblast in vitro.

Therapeutic effect of alpha lipoic acid combined with praziquantel on liver fibrosis induced by Schistosoma mansoni challenged mice

Schistosomiasis is an endemic disease in 74 countries causing more than 250,000 deaths every year. Accordingly, the development of an effective drug for eradication of schistosomiasis is an open research field. The current chemotherapy for control is praziquantel (PZQ). However, PZQ does not improve liver fibrosis. Therefore, the aim of this study is to evaluate the combined effect of alpha lipoic acid (ALA) with PZQ on the liver fibrosis induced by Schistosoma mansoni challenged mice. Evaluation was based on the worm burden count, ova load, granuloma size, and histopathology of the liver. Reduced glutathione (GSH) was measured in the tissue as a biomarker for impaired antioxidant function. Malondialdehyde (MDA) was also measured in the tissue as a biomarker for oxidative stress. The serum level of matrix metalloproteinase 1 was measured as a biomarker for fibrotic status of the liver. Liver function enzymes such as ALT, AST, and GGT were also measured. Four groups of ten mice each were used in this study. The first group was infected with 50 ± 10 S. mansoni cercariae. The second group was also infected and was treated with PZQ 9 weeks post-infection (PI). The third group was treated with PZQ and ALA 9 weeks PI. The fourth group was used a healthy control. The present study revealed remarkable improvement in all parameters measured (parasitological and biochemical) as well as significant improvement of hepatic pathology in the third group which was treated with PZQ and ALA. The treatment of mice with PZQ and ALA results in reduction in the worm burden, egg count, and granuloma size. Furthermore, this combined treatment increased the tissue level of the antioxidant (GSH) and decreased the tissue level of MDA in this group.

Gadolinium exposure disrupts iron homeostasis in cultured cells

Human exposure to gadolinium-based contrast agents can be complicated by nephrogenic systemic fibrosis (NSF). Demonstration of significant quantities of insoluble gadolinium in the skin of NSF patients suggested transmetallation as a mechanism of toxicity of this injury. An alternative pathway for the biological effect of gadolinium is a disruption of iron homeostasis. We tested the postulate that cell exposure to gadolinium increases iron uptake to disrupt intracellular metal homeostasis and impact inflammatory events. Alveolar macrophages, THP1 cells, NHBE cells, and BEAS-2B cells all demonstrated a capacity to import gadolinium from both GdCl(3) and Omniscan. All four cell types similarly imported iron following exposure to ferric ammonium citrate (FAC). Exposure of all cell types to gadolinium and iron resulted in increased iron import relative to cell concentrations following incubation with FAC alone. To analyze for further evidence of changes in iron homeostasis, cell ferritin concentration was determined. Relative to incubation with FAC alone, co-incubation of BEAS-2B cells with gadolinium and FAC resulted in significant increases in ferritin level. Finally, potential effects of gadolinium uptake and associated changes in iron homeostasis on the inflammatory response were evaluated by measuring IL-8. Co-incubation of BEAS-2B cells with both gadolinium and iron resulted in diminished release of IL-8 relative to levels of the cytokine following incubation with gadolinium alone. We conclude that gadolinium impacts cell iron homeostasis to change import and storage of the metal and biological effects of exposure.

N-acetylcysteine prevents carbon tetrachloride-induced liver cirrhosis: role of liver transforming growth factor-beta and oxidative stress

OBJECTIVES

N-acetylcysteine (NAC) is an antioxidant, a precursor of reduced glutathione, and an inhibitor of the profibrotic cytokine liver transforming growth factor-beta (TGF-beta). Carbon tetrachloride (CCl4) cirrhosis is characterized by oxidative stress and fibrosis. Therefore, the aim of this work was to study the effect of NAC on experimental cirrhosis.

METHODS

CCl4 was chronically administered for 8 weeks along with 300 mg/kg of NAC orally once a day. Alkaline phosphatase, alanine aminotransferase, and gamma-glutamyltranspeptidase were measured in plasma. Hydroxyproline, glycogen, lipid peroxidation, glutathione were determined in liver samples by colorimetric methods. TGF-beta was evaluated by western blotting, and a histopathological analysis was performed.

RESULTS

Serum markers of liver damage increased by CCl4 intoxication (P<0.05), whereas cotreatment with NAC prevented these increases (P<0.05); glycogen was depleted in the cirrhotic group (P<0.05), but preserved by NAC (P<0.05). Lipid peroxidation increased and glutathione decreased by the administration of CCl4 (P<0.05), again NAC prevented both effects (P<0.05). Importantly, collagen increased by about seven-fold in the CCl4 group (P<0.05); administration of NAC preserved the normal levels of collagen (P<0.05). Biochemical determinations were corroborated by hematoxylin and eosin, and trichromic stains. Western blots revealed a four-fold increase in TGF-beta in the group receiving CCl4, NAC cotreatment abolished TGF-beta signal (P<0.05).

CONCLUSION

Our results strongly suggest that NAC prevents experimental cirrhosis by two mechanisms: by preventing oxidative stress and by downregulating the profibrogenic cytokine TGF-beta. As NAC is currently used in humans intoxicated with paracetamol, it can be tested in fibrotic or cirrhotic patients under controlled trials.

Melatonin ameliorates experimental hepatic fibrosis induced by carbon tetrachloride in rats

AIM: To investigate the protective effects of melatonin on carbon tetrachloride (CCl₄)-induced hepatic fibrosis in experimental rats.

METHODS: All rats were randomly divided into normal control group, model control group treated with CCl₄ for 12 wk, CCl₄ + NAC group treated with CCl₄ + NAC (100 mg/kg, i.p.) for 12 wk, CCl₄ + MEL-1 group treated with CCl₄ + melatonin (2.5 mg/kg) for 12 wk, CCl₄ + MEL-2 group treated with CCl₄ + melatonin (5.0 mg/kg) for 12 wk, and CCl₄ + MEL-3 group treated with CCl₄ + melatonin (10 mg/kg). Rats in the treatment groups were injected subcutaneously with sterile CCl₄ (3 mL/kg, body weight) in a ratio of 2:3 with olive oil twice a week. Rats in normal control group received hypodermic injection of olive oil at the same dose and frequency as those in treatment groups. At the end of experiment, rats in each group were anesthetized and sacrificed. Hematoxylin and eosin (HE) staining and Van Gieson staining were used to examine changes in liver pathology. Serum activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and protein concentration were measured with routine laboratory methods using an autoanalyzer. Hydroxyproline (HYP) content in liver and malondialdehyde (MDA) and glutathione peroxidase (GPx) levels in liver homogenates were assayed by spectrophotometry. Serum hyaluronic acid (HA), laminin (LN), and procollagen III N-terminal peptide (PIIINP) were determined by radioimmunoassay.

RESULTS: Pathologic grading showed that the fibrogenesis was much less severe in CCl₄ + MEL3 group than in model control group (u = 2.172, P < 0.05), indicating that melatonin (10 mg/kg) can significantly ameliorate CCl₄-induced hepatic fibrotic changes. The serum levels of ALT and AST were markedly lower in CCl₄ + MEL treatment groups (5, 10 mg/kg) than in model control group (ALT: 286.23 ± 121.91 U/L vs 201.15 ± 101.16 U/L and 178.67 ± 103.14 U/L, P = 0.028, P = 0.007; AST: 431.00 ± 166.35 U/L vs 321.23 ± 162.48 U/L and 292.42 ± 126.23 U/L, P = 0.043, P = 0.013). Similarly, the serum laminin (LN) and hyaluronic acid (HA) levels and hydroxyproline (HYP) contents in liver were significantly lower in CCl₄ + MEL-3 group (10 mg/kg) than in model control group (LN: 45.89 ± 11.71 &mgr;g/L vs 55.26 ± 12.30 &mgr;g/L, P = 0.012; HA: 135.71 ± 76.03 &mgr;g/L vs 201.10 ± 68.46 &mgr;g/L, P = 0.020; HYP: 0.42 ± 0.08 mg/g tissue vs 0.51 ± 0.07 mg/g tissue, P = 0.012). Moreover, treatment with melatonin (5, 10 mg/kg) significantly reduced the MDA content and increased the GPx activity in liver homogenates compared with model control group (MDA: 7.89 ± 1.49 noml/mg prot vs 6.29 ± 1.42 noml/mg prot and 6.25 ± 2.27 noml/mg prot, respectively, P = 0.015, P = 0.015; GPx: 49.13 ± 8.72 U/mg prot vs 57.38 ± 7.65 U/mg prot and 61.39 ± 13.15 U/mg prot, respectively, P = 0.035, P = 0.003).

CONCLUSION: Melatonin can ameliorate CCl₄ -induced hepatic fibrosis in rats. The protective effect of melatonin on hepatic fibrosis may be related to its antioxidant activities.

The effects of N-acetylcysteine on bile duct ligation-induced liver fibrosis in rats

Stellate cells are activated by free radicals, and synthesize collagen. N-acetylcysteine (NAC) is a precursor of reduced glutathione and a potent scavenger of hydroxyl radicals and has potential antifibrotic effects. We aimed to test the effects of NAC on bile duct ligation (BDL) induced liver damage in rats. Forty-seven Wistar rats were divided into 5 groups: group 1, BDL+NAC (n=10); group 2, BDL (n=10); group 3, sham+NAC (n=10); group 4, sham (n=10); and group 5, control group (n=10). NAC (50 micromol/kg per day) or saline of single doses were administered intraperitoneally for 28 days. Serum biochemical and liver oxidative stress parameters were studied. Liver collagen level was determined by the method of Lopez de Leon and Rojkind. Liver slides were stained by hematoxylin and eosin and Masson trichrome\Gomory reticulum staining. Aspartate aminotransferase (AST) and alkaline phosphatase levels in the BDL+NAC group were lower than the BDL group and were higher than the control groups (all P< .001). Malondialdehyde, luminal, and glutathione levels in group 1 were lower than the BDL group (P= .01, P= .002, and P< .001) and higher than the control groups (all P< .001). NAC had no effect on alanine aminotransferase (ALT), gammaglutamyl transferase, bilirubin, albumin, or lucigenin levels. Liver collagen levels were higher in the BDL groups (P< .001); however, NAC had no effect on the collagen levels. The BDL groups showed stage 3 fibrosis; all the control groups were normal. NAC improved some biochemical parameters (AST, alkaline phosphatase) and oxidative stress parameters (malondialdehyde, luminol, glutathione) in the BDL model. NAC was found to be effective on cholestasis-induced hepatotoxicity. However, NAC was inefficient as an antifibrotic agent within a 1-month period of administration in the BDL model.

Protection by and anti-oxidant mechanism of berberine against rat liver fibrosis induced by multiple hepatotoxic factors

1. The aim of the present study was to investigate the effect and mechanism of berberine, an alkaloid extracted from the traditional Chinese medicine coptis, on rat liver fibrosis induced by multiple hepatotoxic factors. 2. Male Wistar rats were separated into five groups, a normal control group, a fibrotic control group and fibrotic groups treated with three different doses of berberine. The fibrotic models were established by introduction of multiple hepatotoxic factors, including CCl(4), ethanol and high cholesterol. Rats in the treatment groups were administered 50, 100 or 200 mg/kg berberine, intragastrically, daily for 4 weeks. Serum levels of alanine aminotransferase (ALT) and serum aspartate aminotransferase (AST), hepatic activity of superoxide dismutase (SOD) and hepatic malondialdehyde (MDA) and hepatic hydroxyproline (Hyp) content were determined. Liver biopsies were obtained for histological and immunohistochemical studies to detect the expressions of alpha-smooth muscle actin (SMA) and transforming growth factor (TGF)-beta1. 3. The results showed that, compared with the fibrotic control group, serum levels of ALT and AST and hepatic content of MDA and Hyp were markedly decreased, but the activity of hepatic SOD was significantly increased in berberine-treated groups in a dose-dependent manner. In addition, histopathological changes, such as steatosis, necrosis and myofibroblast proliferation, were reduced and the expression of a-SMA and TGF-b1 was significantly downregulated in the berberine-treated groups (P < 0.01). 4. These results suggest that berberine could be used to prevent experimental liver fibrosis through regulation of the anti-oxidant system and lipid peroxidation.

Regulation of elastin synthesis in pathological states

Elastin is rapidly deposited during late gestation in resilient tissues such as the arteries, lungs and skin owing to increased concentration of its mRNA. Pathological states can arise from congenital insufficiency or disorganization of elastin (cutis laxa). Other elastin deficiencies may be due to excess elastolysis or gene dosage effects. In the former, high turnover rates can be assessed by measurements of elastin degradation products in urine. Excess elastin accumulation by skin fibroblasts is characteristic of genetic diseases such as Buschke-Ollendorff syndrome, Hutchinson-Gilford progeria and keloid. Elastin expression is modulated by peptide growth factors, steroid hormones and phorbol esters, among which transforming growth factor beta (TGF-beta) is an especially potent up-regulator, acting largely through stabilization of mRNA. Recent evidence indicates cutis laxa fibroblasts that express little or no elastin have normal transcriptional activity but abnormal rates of elastin mRNA degradation. This defect is substantially reversed by TGF-beta through mRNA stabilization. Current studies explore the hypothesis that stability determinants lie within the 3' untranslated region of elastin mRNA. Post-transcriptional control of elastin expression appears to be a major regulatory mechanism.

Role of anemia in progression of chronic kidney disease

Anemia is a well-known consequence of chronic kidney disease (CKD), and its prevalence progressively increases when the estimated glomerular filtration rate decreases to less than 60 mL/min/1.73 m2. However, analyses of the consequences of anemia and of the mechanisms of progression of CKD suggest that anemia also could contribute to the deterioration of kidney function. This hypothesis is based mostly on experimental data that imply that hypoxia of tubular cells plays an important role in tubulointerstitial damage associated with CKD and, thus, in the progression of renal failure. It also is supported by the fact that red blood cells represent a major antioxidant component of blood and that oxidative stress appears to contribute to glomerulosclerosis and tubulointerstitial damage. In humans, post hoc analysis of the Reduction of End points in non insulin-dependent diabetes mellitus (NIDDM) with the Angiotensin II Antagonist Losartan study and analyses of smaller prospective cohorts of CKD patients have shown that anemia is an independent risk factor for progression of CKD. In addition, 3 small randomized studies have suggested that anemia correction could slow the progression of CKD. Thus, the existence of a relationship between anemia and progression of CKD is not only plausible biologically, but also is supported by observational studies and by small intervention studies. However, only a large, randomized, prospective trial will be able to establish if anemia correction can slow the progression of CKD effectively.

Anemia management and chronic renal failure progression

Analysis of the biologic effects of erythropoietin and pathophysiology of chronic kidney diseases (CKD) suggests that treatment with erythropoiesis-stimulating agents (ESA) could slow the progression of CKD. By decreasing hypoxia and oxidative stress, it could prevent the development of interstitial fibrosis and the destruction of tubular cells. It could have direct protective effects on tubular cells through its antiapoptotic properties. It could help maintain the integrity of the interstitial capillary network through its effects on endothelial cells. Thus, suggesting that correcting anemia with ESA could slow the progression of CKD is biologically plausible. In patients with CKD, three small prospective studies and a retrospective study have suggested that treatment with ESA may have protective effects. Post-hoc analysis of the Reduction in Endpoints in Noninsulin-dependent Diabetes Mellitus with the Angiotensin II Antagonist Losartan study has also shown that anemia was an independent risk factor for progression of nephropathy in patients with type 2 diabetes. In addition, a large clinical trial, which had to be stopped prematurely because of labeling change for subcutaneous administration of epoetin alfa, suggests that complete normalization of hemoglobin levels is safe in CKD patients not on dialysis and without severe cardiovascular disease. Thus, it seems reasonable to advocate starting a large randomized, prospective study to determine if normalization of hemoglobin concentration can effectively slow the progression of CKD.

Metabolism of alcohol

Most tissues of the body contain enzymes capable of ethanol oxidation or nonoxidative metabolism, but significant activity occurs only in the liver and, to a lesser extent, in the stomach. Hence, medical consequences are predominant in these organs. In the liver, ethanol oxidation generates an excess of reducing equivalents, primarily as NADH, causing hepatotoxicity. An additional system, containing cytochromes P-450 inducible by chronic alcohol feeding, was demonstrated in liver microsomes and found to be a major cause of hepatotoxicity.

N-acetylcysteine attenuates alcohol-induced oxidative stress in he rat

AIM: There is increasing evidence that alcohol-induced liver damage may be associated with increased oxidative stress. We aimed to investigate free-radical scavenger effect of n-acetylcysteine in rats intragastrically fed with ethanol.

METHODS: Twenty-four rats divided into three groups were fed with ethanol (6 g/kg/d, Group 1), ethanol and n-acetylcysteine (1 g/kg, Group 2), or isocaloric dextrose (control group, Group 3) for 4 wk. Then animals were sacrificed under ether anesthesia, intracardiac blood and liver tissues were obtained. Measurements were performed both in serum and in homogenized liver tissues. Malondialdehyde (MDA) level was measured by TBARS method. Glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) levels were studied by commercial kits. Kruskal-Wallis test was used for statistical analysis.

RESULTS: ALT and AST in Group 1 (154 U/L and 302 U/L, respectively) were higher than those in Group 2 (94 U/L and 155 U/L) and Group 3 (99 U/L and 168 U/L) (P = 0.001 for both). Serum and tissue levels of MDA in Group 1 (1.84 nmol/mL and 96 nmol/100 mg-protein) were higher than Group 2 (0.91 nmol/mL and 64 nmol/100 mg-protein) and Group 3 (0.94 nmol/mL and 49 nmol/100 mg-protein) (P < 0.001 for both). On the other hand, serum GSH-Px level in Group 1 (8.21 U/g-Hb) was lower than Group 2 (16 U/g-Hb) and Group 3 (16 U/g-Hb) (P < 0.001). Serum and liver tissue levels of SOD in Group 1 (11 U/mL and 26 U/100 mg-protein) were lower than Group 2 (18 U/mL and 60 U/100 mg-protein) and Group 3 (20 U/mL and 60 U/100 mg-protein) (P < 0.001 for both).

CONCLUSION: This study demonstrated that ethanol-induced liver damage is associated with oxidative stress, and co-administration of n-acetylcysteine attenuates this damage effectively in rat model.

Anemia management and the delay of chronic renal failure progression

Interstitial fibrosis plays a key role in the progression of chronic kidney diseases. Analysis of the biologic effects of erythropoietin and of the pathophysiology of interstitial fibrosis suggest that treatment with epoetin may slow the progression of chronic kidney disease, both by decreasing interstitial fibrosis and by protecting against its consequences. The results of two small prospective studies and of a retrospective one also suggest that treatment with epoetin may have such protective effects.

Effect of Ascorbic Acid and Its Hydrophobic Derivative Palmitoyl Ascorbate on the Redox State of Primary Human Fibroblasts

Ascorbic acid (AA) and its derivatives participate in vitro in oxidative-reductive reactions both as antioxidants and as prooxidants. The physiological relevance of these prooxidant effects of AA and its derivatives remains unclear. There is little evidence that AA can initiate formation of reactive oxygen species (ROS) or lipid peroxidation in cells or tissue. In order to examine the effect of AA and its derivative palmitoyl ascorbate on in situ intracellular ROS production and lipid peroxidation, 2('),7(')-dichlorofluorescin diacetate (DCFH-DA) and cis-parinaric acid were used as fluorescent probes in cultural neonatal foreskin fibroblasts. The results demonstrated that the effect of AA depended on the in vitro growth conditions. AA induced augmentation of the intracellular ROS concentration in newly plated (24 hours) cells. However, in cells cultured for 72 hours, AA had a different effect: it moderately reduced intracellular ROS concentration but stimulated lipid peroxidation in the cytoplasmic membrane. Palmitoyl ascorbate demonstrated significant inhibition of intracellular DCFH-DA oxidation presumably caused by inhibition of reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase.

The ability of mineral dusts and fibres to initiate lipid peroxidation. Part II: relationship to different particle-induced pathological effects

Exposure to pathogenic mineral dusts and fibres is associated with pulmonary changes including fibrosis and cancer. Investigations into aetiological mechanisms of these diseases have identified modifications in specific macromolecules as well as changes in certain early processes, which have preceded fibrosis and cancer. Peroxidation of lipids is one such modification, which is observed following exposure to mineral dusts and fibres. Their ability to initiate lipid peroxidation and the parameters that determine this ability have recently been reviewed. Part II of this review examines the relationship between the capacity of mineral dusts and fibres to initiate lipid peroxidation and a number of pathological changes they produce. The oxidative modification of polyunsaturated fatty acids is a major contributor to membrane damage in cells and has been implicated in a great variety of pathological processes. In most pathological conditions where an induction of lipid peroxidation is observed it is assumed to be the consequence of disease, without further establishing if the induction of lipid peroxidation may have preceded or accompanied the disease. In the great majority of instances, however, despite the difficulty in proving this association, a causal relationship between lipid peroxidation and disease cannot be ruled out.

Hepatic, metabolic, and nutritional disorders of alcoholism: from pathogenesis to therapy

Much progress has been made in the understanding of the pathogenesis of alcoholic liver disease, resulting in an improvement in treatment. Nutritional deficiencies should be corrected when present but, because of the alcohol-induced disease process, some of the nutritional requirements change. For instance, methionine, one of the essential amino acids for humans, must be activated to S-adenosylmethionine (SAMe), but, in severe liver disease, the activity of the corresponding enzyme is depressed. Therefore, the resulting deficiencies and associated pathology can be attenuated by the administration of SAMe, but not by methionine. Similarly, phosphatidylethanolamine methyltransferase (PEMT) activity, which is important for hepatic phosphatidylcholine (PC) synthesis, is also depressed in alcoholic liver disease, therefore calling for the administration of the products of the reaction. Inasmuch as free radical generation by the ethanol-induced CYP2E1 plays a key role in the oxidative stress, inhibitors of this enzyme have great promise and PPC, which is presently being evaluated clinically, is particularly interesting because of its innocuity. In view of the striking negative interaction between alcoholic liver injury and hepatitis C, an antiviral agent is eagerly awaited that, unlike Interferon, is not contraindicated in the alcoholic. Antiinflamatory agents may also be useful. In addition to steroids, down-regulators of cytokines and endotoxin are being considered. Finally, anticraving agents such as naltrexone or acamprosate should be incorporated into any contemplated therapeutic cocktail.

Micronutrients, vitamins, and cancer risk

There is now considerable evidence that a high intake of fruit and vegetables can decrease the risk of developing cancer. While it is by no means clear how this particular diet alters cancer risk, there is substantial metabolic and experimental evidence to implicate antioxidant micronutrients, The dietary components include some vitamins, such as C and E, the carotenoids, and the flavinoids. In chemical systems, cell culture, and experimental animals, these components have the ability to quench the carcinogenic potential of reactive oxygen species and other carcinogens, such as N-nitrosocompounds. Some of these micronutrients can act synergistically, and high concentrations are often found in tissues, such as the leucocytes and mucosal cells, that are particularly prone to reactive species attack. Experimental systems containing these micronutrients also appear to be able to reduce DNA damage and mutagenesis. However, assessment of individual vitamin intake, as opposed to fruit and vegetable consumption, does not increase the protective association of these components, and the results of intervention studies in man, especially with carotenoids, have been disappointing. We await the results of other clinical trials, but as yet, there is insufficient evidence to recommend supplements of these particular micronutrients for the prevention of cancer. However, it would be prudent to suggest changes in diet that would increase consumption of fruit and vegetables, such as a diet is clearly associated with protection.

Dilinoleoylphosphatidylcholine decreases hepatic stellate cell activation

The prevention of cirrhosis in alcohol-fed baboons by the administration of a soybean extract-43% to 50% of which was dilinoleoyl-phosphatidylcholine (DLPC) and 24% of which was 1,palmitoyl 2,linoleoyl-phosphatidylcholine (PLPC)-was associated with a significant reduction in the number of stellate cells transformed to myofibroblast-like cells. To study whether these two major phospholipids affect the similar transformation that occurs by culturing stellate cells on uncoated plastic, we assessed their effects on proliferation (by (methyl-3H)-thymidine incorporation into DNA), expression of alpha-smooth muscle actin and type I procollagen (by densitometry of Western blots), and collagen synthesis (by incorporation of tritiated proline into collagenase-digestible proteins). These manifestations of stellate cell activation were decreased by 10 micromol/L DLPC but not by 10 micromol/L PLPC when compared with controls incubated either with 17 mmol/L ethanol (used as solvent for the phospholipids) or without addition. These agents did not affect cell viability, contamination with other cells, or the capacity of stellate cells to synthesize protein. Thus DLPC specifically decreases the in vitro activation of stellate cells, as judged by the decreases in proliferative activity, alpha-smooth muscle actin and procollagen I expressions, and collagen synthesis, whereas PLPC did not show such effects. alpha-Procollagen (type I) mRNA was not affected by DLPC, suggesting a post-translational effect. The reduction in the activation of hepatic stellate cells by DLPC may be responsible for, or at least contribute to, the prevention of fibrosis by the polyenylphosphatidylcholine mixture administered in vivo.

Acylated ascorbate stimulates collagen synthesis in cultured human foreskin fibroblasts at lower doses than does ascorbic acid

Acylated derivatives of ascorbic acid were found to be active in a number of biochemical and physiological processes. In the present study we investigated the effects of 6-O-palmitoyl ascorbate on collagen synthesis by cultured foreskin human fibroblasts. Our observations indicate a marked stimulatory effect on collagen synthesis by 6-O-palmitoyl ascorbate in the concentration range of 5-20 microM, while the synthesis stimulated by ascorbic acid was maximal at concentrations of 20-100 microM. Cells treated with 10 microM palmitoyl ascorbate for 36 h exhibited a production of collagen threefold greater than those in the presence of 10 microM ascorbic acid, and it was about the same as in cells treated with 100 microM ascorbic acid. By 48 h differences were not significant. Acylated ascorbate impaired vitality of the treated fibroblasts at concentrations exceeding 20 microM in media supplemented with 0.5% FCS. However, most of the cytotoxic effect was neutralized by FCS at a concentration of 10%. The resistance of acylated ascorbate against oxidative degradation as well as the role of free radicals in the modulation of collagen synthesis by ascorbic acid and by its derivatives is discussed.

Pathogenesis of alcoholic liver disease with particular emphasis on oxidative stress

Oxidative stress is well recognized to be a key step in the pathogenesis of ethanol-associated liver injury. Ethanol administration induces an increase in lipid peroxidation either by enhancing the production of oxygen reactive species and/or by decreasing the level of endogenous antioxidants. Numerous experimental studies have emphasized the role of the ethanol-inducible cytochrome P450 in the microsomes and the molybdo-flavoenzyme xanthine oxidase in the cytosol. This review shows the putative role of ethanol-induced disturbances in iron metabolism in relation to iron as a pro-oxidant factor. Ethanol administration also affects the mitochondrial free radical generation. Many previous studies suggest a role for active oxygens in ethanol-induced mitochondrial dysfunction in hepatocytes. Recent studies in our laboratory in the Department of Internal Medicine, Keio University, using a confocal laser scanning microscopic system strongly suggest that active oxidants generated during ethanol metabolism produce mitochondrial membrane permeability transition in isolated and cultured hepatocytes. In addition, acetaldehyde, ethanol consumption-associated endotoxaemia and subsequent release of inflammatory mediators may cause hepatocyte injury via both oxyradical-dependent and -independent mechanisms. These cytotoxic processes may lead to lethal hepatocyte injury. Investigations further implicate the endogenous glutathione-glutathione peroxidase system and catalase as important antioxidants and cytoprotective machinery in the hepatocytes exposed to ethanol.

Ethanol metabolism, cirrhosis and alcoholism

Alcohol-induced tissue damage results from associated nutritional deficiencies as well as some direct toxic effects, which have now been linked to the metabolism of ethanol. The main pathway involves liver alcohol dehydrogenase which catalyzes the oxidation of ethanol to acetaldehyde, with a shift to a more reduced state, and results in metabolic disturbances, such as hyperlactacidemia, acidosis, hyperglycemia, hyperuricemia and fatty liver. More severe toxic manifestations are produced by an accessory pathway, the microsomal ethanol oxidizing system involving an ethanol-inducible cytochrome P450 (2E1). After chronic ethanol consumption, there is a 4- to 10-fold induction of 2E1, associated not only with increased acetaldehyde generation but also with production of oxygen radicals that promote lipid peroxidation. Most importantly, 2E1 activates many xenobiotics to toxic metabolites. These include solvents commonly used in industry, anaesthetic agents, medications such as isoniazid, over the counter analgesics (acetaminophen), illicit drugs (cocaine), chemical carcinogens, and even vitamin A and its precursor beta-carotene. Furthermore, enhanced microsomal degradation of retinoids (together with increased hepatic mobilization) promotes their depletion and associated pathology. Induction of 2E1 also yields increased acetaldehyde generation, with formation of protein adducts, resulting in antibody production, enzyme inactivation, decreased DNA repair, impaired utilization of oxygen, glutathione depletion, free radical-mediated toxicity, lipid peroxidation, and increased collagen synthesis. New therapies include adenosyl-L-methionine which, in baboons, replenishes glutathione, and attenuates mitochondrial lesions. In addition, polyenylphosphatidylcholine (PPC) fully prevents ethanol-induced septal fibrosis and cirrhosis, opposes ethanol-induced hepatic phospholipid depletion, decreased phosphatidylethanolamine methyltransferase activity and activation of hepatic lipocytes, whereas its dilinoleoyl species increases collagenase activity. Current clinical trials with PPC are targeted on susceptible populations, namely heavy drinkers at precirrhotic stages.

Ascorbate differentially regulates elastin and collagen biosynthesis in vascular smooth muscle cells and skin fibroblasts by pretranslational mechanisms

Ascorbate contributes to several metabolic processes including efficient hydroxylation of hydroxyproline in elastin, collagen, and proteins with collagenous domains, yet hydroxyproline in elastin has no known function. Prolyl hydroxylation is essential for efficient collagen production; in contrast, ascorbate has been shown to decrease elastin accumulation in vitro and to alter morphology of elastic tissues in vivo. Ascorbate doses that maximally stimulated collagen production (10-200 microM) antagonized elastin biosynthesis in vascular smooth muscle cells and skin fibroblasts, depending on a combination of dose and exposure time. Diminished elastin production paralleled reduced elastin mRNA levels, while collagen I and III mRNAs levels increased. We compared the stability of mRNAs for elastin and collagen I with a constitutive gene after ascorbate supplementation or withdrawal. Ascorbate decreased elastin mRNA stability, while collagen I mRNA was stabilized to a much greater extent. Ascorbate withdrawal decreased collagen I mRNA stability markedly (4.9-fold), while elastin mRNA became more stable. Transcription of elastin was reduced 72% by ascorbate exposure. Differential effects of ascorbic acid on collagen I and elastin mRNA abundance result from the combined, marked stabilization of collagen mRNA, the lesser stability of elastin mRNA, and the significant repression of elastin gene transcription.

Oxidative damage and fibrogenesis

Various chronic disease processes are characterized by progressive accumulation of connective tissue under-going fibrotic degeneration. Evidence of oxidative reactions is often associated with fibrogenesis occurring in liver, lung, arteries, and nervous system. Moreover, an increasing bulk of experimental and clinical data supports a contributory role of oxidative stress in the pathogenesis of this kind of disease. Indeed, many etiological agents of fibrogenesis stimulate free radical reactions either directly or through inflammatory stimuli. Free radicals, as well as products of their reaction with biomolecules, appear to modulate the activity of the two cellular types mainly involved in the process, namely phagocytes and extracellular matrix-producing cells. Lipid peroxidation and certain lipid peroxidation products induce genetic overexpression of fibrogenic cytokines, the key molecules in the pathomechanisms of fibrosis, as well as increased transcription and synthesis of collagen. Both these events can be downregulated, at least in experimental models, by the use of antioxidants. The effect of oxidative stress on cytokine gene expression appears to be an important mechanism by which it promotes connective tissue deposition.

Role of oxidative stress and antioxidant therapy in alcoholic and nonalcoholic liver diseases

The main pathway for the hepatic oxidation of ethanol to acetaldehyde proceeds via ADH and is associated with the reduction of NAD to NADH; the latter produces a striking redox change with various associated metabolic disorders. NADH also inhibits xanthine dehydrogenase activity, resulting in a shift of purine oxidation to xanthine oxidase, thereby promoting the generation of oxygen-free radical species. NADH also supports microsomal oxidations, including that of ethanol, in part via transhydrogenation to NADPH. In addition to the classic alcohol dehydrogenase pathway, ethanol can also be reduced by an accessory but inducible microsomal ethanoloxidizing system. This induction is associated with proliferation of the endoplasmic reticulum, both in experimental animals and in humans, and is accompanied by increased oxidation of NADPH with resulting H2O2 generation. There is also a concomitant 4- to 10-fold induction of cytochrome P4502E1 (2E1) both in rats and in humans, with hepatic perivenular preponderance. This 2E1 induction contributes to the well-known lipid peroxidation associated with alcoholic liver injury, as demonstrated by increased rates of superoxide radical production and lipid peroxidation correlating with the amount of 2E1 in liver microsomal preparations and the inhibition of lipid peroxidation in liver microsomes by antibodies against 2E1 in control and ethanol-fed rats. Indeed, 2E1 is rather "leaky" and its operation results in a significant release of free radicals. In addition, induction of this microsomal system results in enhanced acetaldehyde production, which in turn impairs defense systems against oxidative stress. For instance, it decreases GSH by various mechanisms, including binding to cysteine or by provoking its leakage out of the mitochondria and of the cell. Hepatic GSH depletion after chronic alcohol consumption was shown both in experimental animals and in humans. Alcohol-induced increased GSH turnover was demonstrated indirectly by a rise in alpha-amino-n-butyric acid in rats and baboons and in volunteers given alcohol. The ultimate precursor of cysteine (one of the three amino acids of GSH) is methionine. Methionine, however, must be first activated to S-adenosylmethionine by an enzyme which is depressed by alcoholic liver disease. This block can be bypassed by SAMe administration which restores hepatic SAMe levels and attenuates parameters of ethanol-induced liver injury significantly such as the increase in circulating transaminases, mitochondrial lesions, and leakage of mitochondrial enzymes (e.g., glutamic dehydrogenase) into the bloodstream. SAMe also contributes to the methylation of phosphatidylethanolamine to phosphatidylcholine. The methyltransferase involved is strikingly depressed by alcohol consumption, but this can be corrected, and hepatic phosphatidylcholine levels restored, by the administration of a mixture of polyunsaturated phospholipids (polyenylphosphatidylcholine). In addition, PPC provided total protection against alcohol-induced septal fibrosis and cirrhosis in the baboon and it abolished an associated twofold rise in hepatic F2-isoprostanes, a product of lipid peroxidation. A similar effect was observed in rats given CCl4. Thus, PPC prevented CCl4- and alcohol-induced lipid peroxidation in rats and baboons, respectively, while it attenuated the associated liver injury. Similar studies are ongoing in humans.

Ascorbic acid and atherosclerotic cardiovascular disease

In this chapter, we have briefly reviewed the current scientific knowledge of the role of vitamin C in the prevention of atherosclerosis and its associated clinical manifestations. There is good evidence from animal studies that vitamin C can slow the progression of experimental atherosclerosis. Most of these studies, however, were done either in guinea pigs, using ascorbic acid depletion, or in cholesterol-fed rabbits, using ascorbic acid supplementation. Both animal models have limitations, as guinea pigs are not a well-established (nor well-studied) model of atherosclerosis, and rabbits develop atherosclerosis at high serum beta-VLDL cholesterol levels, and in addition can synthesize ascorbic acid. In contrast, humans develop atherosclerosis spontaneously and readily at moderately elevated serum LDL cholesterol levels and have lost the ability to synthesize ascorbic acid. Thus, the animal studies discussed, although quite promising and suggestive of an anti-atherogenic effect of ascorbic acid, need to be expanded to primates before more definitive conclusions can be drawn. Similar to the animal data, the current evidence from epidemiological studies on the role of vitamin C in the prevention of CVD is inconclusive, with some studies showing a very strong correlation between increased vitamin C intake and incidence of CVD events and other studies showing no correlation at all. Studies on CVD risk factors indicate that vitamin C may moderately decrease total serum cholesterol levels, increase HDL levels, and exert a hypotensive effect. These findings are particularly intriguing and should be pursued vigorously in basic research studies to elucidate biological mechanisms. In addition, it appears that large placebo-controlled, double-blind, randomized trials of vitamin C supplementation (without simultaneous supplementation with vitamin E) in populations with a wide range of vitamin C body levels are needed in order to confirm or refute a role for vitamin C in the prevention of CVD. Unfortunately, no such trials are currently being conducted. The possible mechanisms by which ascorbic acid may affect the development of atherosclerosis and the onset of acute coronary events include effects on arterial wall integrity related to biosynthesis of collagen and GAGs, altered cholesterol metabolism mediated by vitamin C-dependent conversion of cholesterol to bile acids, and effects on triglyceride levels via modulation of lipoprotein lipase activity. A particularly intriguing possible mechanism for the anti-atherogenic effect of vitamin C is prevention of atherogenic, oxidative modification of LDL. Numerous in vitro studies have demonstrated that ascorbic acid strongly inhibits LDL oxidation by a variety of mechanisms. The potential effects of ascorbic acid on platelet function and EDRF metabolism are particularly intriguing, as they might have widespread consequences for the prevention of atherosclerotic lesion development as well as acute clinical events. Thus, both metabolic and antioxidant functions may contribute to the possible reduction of CVD risk by vitamin C.

Alcohol and the liver: 1994 update

This article reviews current concepts on the pathogenesis and treatment of alcoholic liver disease. It has been known that the hepatotoxicity of ethanol results from alcohol dehydrogenase-mediated excessive generation of hepatic nicotinamide adenine dinucleotide, reduced form, and acetaldehyde. It is now recognized that acetaldehyde is also produced by an accessory (but inducible) microsomal pathway that additionally generates oxygen radicals and activates many xenobiotics to toxic metabolites, thereby explaining the increased vulnerability of heavy drinkers to industrial solvents, anesthetics, commonly used drugs, over-the-counter medications, and carcinogens. The contribution of gastric alcohol dehydrogenase to the first-pass metabolism of ethanol and alcohol-drug interactions is discussed. Roles for hepatitis C, cytokines, sex, genetics, and age are now emerging. Alcohol also alters the degradation of key nutrients, thereby promoting deficiencies as well as toxic interactions with vitamin A and beta carotene. Conversely, nutritional deficits may affect the toxicity of ethanol and acetaldehyde, as illustrated by the depletion in glutathione, ameliorated by S-adenosyl-L-methionine. Other "supernutrients" include polyunsaturated lecithin, shown to correct the alcohol-induced hepatic phosphatidylcholine depletion and to prevent alcoholic cirrhosis in nonhuman primates. Thus, a better understanding of the pathology induced by ethanol is now generating improved prospects for therapy.

Mechanisms of ethanol-drug-nutrition interactions

Mechanisms of the toxicologic manifestations of ethanol abuse are reviewed. Hepatotoxicity of ethanol results from alcohol dehydrogenase-mediated excessive hepatic generation of nicotinamide adenine dinucleotide and acetaldehyde. It is now recognized that acetaldehyde is also produced by an accessory (but inducible) pathway, the microsomal ethanol-oxidizing system, which involves a specific cytochrome P450. It generates oxygen radicals and activates many xenobiotics to toxic metabolites, thereby explaining the increased vulnerability of heavy drinkers to industrial solvents, anesthetics, commonly used drugs, over-the-counter medications and carcinogens. The contribution of gastric alcohol dehydrogenase to the first pass metabolism of ethanol and alcohol-drug interactions is now recognized. Alcohol also alters the degradation of key nutrients, thereby promoting deficiencies as well as toxic interactions with vitamin A and beta-carotene. Conversely, nutritional deficits may affect the toxicity of ethanol and acetaldehyde, as illustrated by the depletion in glutathione, ameliorated by S-adenosyl-L-methionine. Other supernutrients include polyenylphosphatidylcholine, shown to correct the alcohol-induced hepatic phosphatidylcholine depletion and to prevent alcoholic cirrhosis in non-human primates. Thus, a better understanding of the pathology induced by ethanol has now generated improved prospects for therapy.