Pharmacological activation of nuclear factor erythroid 2-related factor-2 prevents hyperglycemia-induced renal oxidative damage: Possible involvement of O-GlcNAcylation

Hyperglycemia is a major risk factor for kidney diseases. Oxidative stress, caused by reactive oxygen species, is a key factor in the development of kidney abnormalities related to hyperglycemia. The nuclear factor erythroid 2-related factor-2 (Nrf2) plays a crucial role in defending cells against oxidative stress by activating genes that produce antioxidants. L-sulforaphane (SFN), a drug that activates Nrf2, reduces damage caused by hyperglycemia. Hyperglycemic Wistar rats and HEK 293 cells maintained in hyperglycemic medium exhibited decreased Nrf2 nuclear translocation and reduced expression and activity of antioxidant enzymes. SFN treatment increased Nrf2 activity and reversed decreased renal function, oxidative stress and cell death associated with hyperglycemia. To investigate mechanisms involved in hyperglycemia-induced reduced Nrf2 activity, we addressed whether Nrf2 is modified by O-linked β-N-acetylglucosamine (O-GlcNAc), a post-translational modification that is fueled in hyperglycemic conditions. In vivo, hyperglycemia increased O-GlcNAc-modified Nrf2 expression. Increased O-GlcNAc levels, induced by pharmacological inhibition of OGA, decreased Nrf2 activity in HEK 293 cells. In conclusion, hyperglycemia reduces Nrf2 activity, promoting oxidative stress, cell apoptosis and structural and functional renal damage. Pharmacological treatment with SFN attenuates renal injury. O-GlcNAcylation negatively modulates Nrf2 activity and represents a potential mechanism leading to oxidative stress and renal damage in hyperglycemic conditions.

Hepatic injury induced by thioacetamide causes aortic endothelial dysfunction by a cyclooxygenase-dependent mechanism

Liver cirrhosis is associated with a wide range of cardiovascular abnormalities including hyperdynamic circulation and cirrhotic cardiomyopathy. The pathogenic mechanisms of these cardiovascular changes are multifactorial and include vascular dysregulations.

AIM

The present study tested the hypothesis that the systemic vascular hyporesponsiveness in thioacetamide (TAA)-induced liver injury model is dependent on nitric oxide (NO) and cyclooxygenase (COX) derivatives.

MAIN METHODS

Wistar rats were treated with TAA for eight weeks to induce liver injury.

KEY FINDINGS

The maximal contractile response in concentration-effect curves to phenylephrine was decreased in aorta from TAA-treated rats, but no differences were found in aorta without endothelium, suggesting an endothelium-dependent mechanism in decreased contractile response. There was no difference in the contractile response with and without L-NAME (N(ω)-nitro-l-arginine methyl ester) in rats with liver injury, showing that the TAA treatment impairs NO synthesis. Pre-incubation of the aorta with indomethacin, a COX-inhibitor, normalized the reduced contractile response to phenylephrine in arteries from TAA group. Also, COX-2 and iNOS (inducible nitric oxide syntase) protein expression was increased in aorta from TAA group compared to control group. Animals submitted to TAA treatment had a reduction in systolic blood pressure. Our findings demonstrated that liver injury induced by TAA caused a decrease in aortic contractile response by a COX-dependent mechanism but not by NO release. Also, it was demonstrated an inflammatory process in the aorta of TAA-treated rats by increased expression of COX-2 and iNOS.

SIGNIFICANCE

Therefore, there is an essential contribution of COX-2 activation in extra-hepatic vascular dysfunction and inflammation present in cirrhosis induced by TAA.

Oxygenated monoterpenes-rich volatile oils as potential antifungal agents for dermatophytes

Essential oils (EOs) extracted from Lavandula luisieri and Cymbopogon citratus were tested for their antifungal activity against ten clinical isolates of dermatophytes isolated from cases of tinea pedis. Inhibition of conidial germination and antifungal drug/EO combination assay were tested on two ATCC reference strains of Trichophyton rubrum and Trichophyton mentagrophytes. EOs were characterised by high amount of oxygenated monoterpenes in their composition. Strong antifungal activity was observed for the majority of clinical strains, and fungicidal activity was demonstrated. Positive interaction between L. luisieri EO combined with terbinafine was observed against terbinafine-resistant strain (Tr ATCC MYA-4438). Significative reduction of the germination was observed above 100 μg mL^-1. Both oils were safe to macrophage mammalian cells at tested concentration. This study describes the antifungal activity of L. luisieri and C. citratus EOs against dermatophytes, which could be useful in designing new formulations for topical treatments.

Inter-retrotransposon-amplified polymorphism markers for germplasm characterization in Manihot esculenta (Euphorbiaceae)

Manioc, Manihot esculenta, is economically important in many tropical and subtropical countries. The genetic variability of the species has not been fully explored, and new information may help expand its use. Molecular markers based on retrotransposons have good potential for analysis of genetic diversity given their abundance in the genome. Eight long terminal repeat retrotransposons were selected for the development of inter-retrotransposon-amplified polymorphism markers. To test these primers, we analyzed 32 varieties from Anori, 30 from Manicoré and 10 Mandiocabas from the Manioc Germplasm Bank at Embrapa Western Amazonia. The six informative primer pairs yielded 20- 60 polymorphic bands, averaging 92% polymorphism (51.7-98.4) and 0.37 heterozygosity (0.17 to 0.40), with a Shannon information index of 0.54 (0.26-0.59). These markers can be used to explore the genetic diversity of manioc.

Lack of chemopreventive effects of ginger on colon carcinogenesis induced by 1,2-dimethylhydrazine in rats

Ginger (Zingiber officinale Roscoe) has been proposed as a promising candidate for cancer prevention. Its modifying potential on the process of colon carcinogenesis induced by 1,2-dimethylhydrazine (DMH) was investigated in male Wistar rats using the aberrant crypt foci (ACF) assay. Five groups were studied: Groups 1-3 were given four s.c. injections of DMH (40 mg/kg b.w.) twice a week, during two weeks, whereas Groups 4 and 5 received similar injections of EDTA solution (DMH vehicle). After DMH-initiation, the animals were fed a ginger extract mixed in the basal diet at 0.5% (Group 2) and 1.0% (Groups 3 and 4) for 10 weeks. All rats were killed after 12 weeks and the colons were analyzed for ACF formation and crypt multiplicity. The rates of cell proliferation and apoptosis were also evaluated in epithelial colonic crypt cells. Dietary consumption of ginger at both dose levels did not induce any toxicity in the rats, but ginger meal at 1% decreased significantly serum cholesterol levels (p<0.038). Treatment with ginger did not suppress ACF formation or the number of crypts per ACF in the DMH-treated group. Dietary ginger did not significantly change the proliferative or apoptosis indexes of the colonic crypt cells induced by DMH. Thus, the present results did not confirm a chemopreventive activity of ginger on colon carcinogenesis as analyzed by the ACF bioassay and by the growth kinetics of the colonic mucosa.

In vitro reassembly of the malolactic fermentation pathway of Leuconostoc oenos (Oenococcus oeni)

The mechanism of metabolic energy generation by malolactic fermentation was studied with artificial membrane vesicles of Leuconostoc oenos (Oenococcus oeni). (Note that although L. oenos was recently reclassified as O. oeni [L. M. T. Dicks, F. Dellaglio, and M. D. Collins, Int. J. Syst. Bacteriol. 45:395-397, 1995], the old designation was kept in the present work.) Purified malolactic enzyme was entrapped in artificial membrane vesicles prepared from L. oenos cells able to transport L-malate. We show that the in vitro reconstituted system, including an electrogenic L-malate carrier and the decarboxylating malolactic enzyme, generated a proton motive force that was able to drive intravesicular accumulation of leucine.

[Nutritional assistance to patients during radiotherapy]

With the aim of assessing the possible benefits of nutritional therapy, 140 patients were prospectively studied during radiotherapy of the head and neck (81%) and esophageal cancer (19%). Mean age was 56.0 (17-80), with 114 males and 26 females. Duration of both nutrition and radiotherapy was 78.0 +/- 45 days. Tube feeding was the primary modality in 50.7% of the population, and oral regimens in the remaining 49.3%, but associations between the methods were also used. Enteral diets were supplied under the supervision of a specialized tem for home alimentation (PROSNED). Compliance to the program was 100%, and a lymphocyte count diminished along this period (1933 +/- 1033 vs 1265 +/- 688, p. 0.001). A subjective improvement was reported by 84% of the population, and total calorie intake, that was below 60% of estimated needs in 100% of the cases initially, significantly improved to just 40% inadequate at the end of the observations. Radiotherapy was associated with mucositis in 21% of the patients, taste changes in 79%, xerostomy in 81%, anorexia in 66% and odinophagia in 59%. In the individuals selected for enteral feeding, side-effects were represented by technical problems (20%) and gastrointestinal disorders (13%). All patients completed the nutritional support program and there was no mortality in this series. It is concluded that; 1) Early nutritional support during radiotherapy was able to maintain or improve the nutritional status; 2) Tube feeding, alone or in combination with oral diets, was indicated whenever appropriate and contributed to fulfillment of the energy requirements; 3) Reduction of total lymphocytes could not be prevented by the mentioned therapy; 4) Complications of enteral alimentation were mild and affected a small proportion of the population; 5) Troubles induced by radiotherapy were as frequent as expected, and tended to disturb the intake of food; 6) The compliance to the therapeutic plan was excellent and can be attributed to the efforts of the multidisciplinary team as well as to the help of the specialized home alimentation unit (PROSNED): Diet therapy. Cancer. Nutritional assessment. Radiotherapy. Nutritional support.

[Nutritional support, free radicals, and antioxidants]

Antioxidants and free radical scavengers are molecules endowed with the ability of neutralizing reactive oxygen species that may accumulate in the organism during various pathologic processes. In circumstances of peroxidation of lipids and damage to enzymatic chains, cell membranes and other structures may be followed by functional losses and even cell death. Many antioxidants are normal constituents of the diet in the form of vitamins, trace elements and amino acids, and other useful properties cannot be easily distinguished from their free-radical scavenging abilities. Much controversy surrounds also the indications of these substances, both for prophylactic and therapeutic purposes. The first large-scale population studies have only recently been arranged, and additional investigations are required in many promising areas, including cancer patients undergoing chemo and radiotherapy.

Uniport of monoanionic L-malate in membrane vesicles from Leuconostoc oenos

L-malate transport was studied in membrane vesicles from Leuconostoc oenos MLE(-) (mutant lacking malolactic enzyme) which were fused with liposomes containing beef heart cytochrome c oxidase as a proton-motive-force-generating system. In these hybrid membranes, accumulation of L-malate was observed in response to a pH gradient (delta pH), with the inside alkaline, but was strongly inhibited by a membrane potential (delta psi) of normal polarity (inside negative). Imposition of a delta psi, with the inside positive, by means of valinomycin-mediated potassium influx, resulted in a rapid accumulation of L-malate, indicating that L-malate was taken up in an anionic form. The results are consistent with a uniport mechanism facilitating the uptake of monoanionic L-malate, the dominant species at the low pH of the experiments. Kinetic analysis of delta pH-driven L-malate uptake in the pH range 3.0-5.8, yielded apparent affinity constants that varied less than twofold when calculated on the basis of the concentrations of monoanionic L-malate, whereas the values differed 2-3 orders of magnitude for the other species. At L-malate concentrations above 1 mM, a non-saturable transport component became apparent which may reflect passive influx of L-malic acid. Substrate specificity studies indicated that citrate and L-malate (and possibly D-lactate and L-lactate) compete for a single general carboxylate transport system. The carboxylate transport system catalysed homologous L-malate and heterologous L-malate/citrate exchange with rates similar to the rate of L-malate efflux. Since metabolic energy is conserved during malolactic fermentation in L. oenos, the underlying mechanism most likely involves electrogenic monoanionic L-malate uptake, in combination with H+ consumption in the cytoplasm, followed by diffusion outwards of lactic acid plus carbon dioxide.

[Contamination of enteral diet solutions in nosocomial environment]

The gastrointestinal tract is comparatively resistant to food-born germs, but recent studies suggest that nosocomial infections may be triggered by this route. In a study with industrialized diets, prepared with aseptic technique and stored up to 24 hours, aerobic and anaerobic contaminants were searched. Samples were taken after 0.8 and 24 hours, whereas half of these last two analyses were carried out in material left at room temperature, and the other half in refrigerated diets. Initial examination revealed 50% of positive cultures, but part of this was due to non-pathogenic Bacillus germs. After 8 and 24 hours 90% of the samples grew organisms, again with a large proportion of Bacillus, but also with several Gram-negative bacteria, as well as rare Gram-positives. Diarrhea and fever were not registered in patients submitted to enteral nutrition during the study period, nor could any episodes of bacteremia or septic shock be attributed to contaminated feeding material. This lack of clinical consequences of the reported bacterial isolations is not unexpected, and suggests that low concentrations of microorganisms were probably present in the preparations, below a critical level. Nevertheless, attention will be required in the future for better quality control of enteral nutrition mixtures, specially when resistant strains of Gram-negative species are identified, and also in the management of debilitated or immunologically compromised hosts.

[Renal changes caused by pentavalent antimonial (Glucantime) hypersensitivity in American tegumentary leishmaniasis. Report of a case]

The authors report one case of leishmaniasis in a 60 year old patient who developed renal failure after treatment with Glucantime. With the interruption of these drug the patient recovered her normal renal function, and a new treatment with Amphotericin B was tried with complete cicatrization of the lesions.

[Papillary carcinoma of the male breast]

The authors described a breast intraductal papillary carcinoma, of a 73 year old man, with a Paget disease presentation. The pathological features of differential diagnosis were discussed and enunciated the literary review of the etiology and prognosis.

[Black grain mycetoma caused by Madurella grisea]

The authors reported one case of eumycotic mycetoma due to Madurella grisea (black grains) occurred on the right foot of the patient studied. The structure, microscopic morphology and therapeutic evolution are also studied and reported.