Levels of mannose-binding lectin in individuals with visceral leishmaniasis in the northeast region of Brazil.

Visceral leishmaniasis (VL) is one of the seven priority endemic diseases in the world. The clinical outcome of many infections is not only dependent on the pathogenic organism, but also on the genetic variability of the host susceptibility to infection. Mannose-binding lectin (MBL) is a protein that plays an important role in the innate immune system. The aim of this study was to compare the serum levels of MBL between healthy controls and carriers of VL. The VL cases were recruited randomly from the main hospitals and referral outpatient clinics for VL in São Luís, and from home visits. Determination of MBL protein levels was performed by enzyme-linked immunosorbent assay. Of the 161 patients with VL and the 161 healthy controls, 60.9 and 67.1% had high levels of MBL, respectively. There was no significant difference in MBL levels between cases and controls. Low socioeconomic status and living conditions are conducive to the occurrence of VL. Owing to the small number of existing studies, it is extremely important to conduct further studies on MBL levels and susceptibility to VL, especially in regions where the disease is endemic, such as Maranhão, Brazil.

Characterization and genome organization of a repetitive element associated with the nucleolus organizer region in Leporinus elongatus (Anostomidae: Characiformes).

Chromosome mapping and studies of the genomic organization of repetitive DNA sequences provide valuable insights that enhance our evolutionary and structural understanding of these sequences, as well as identifying chromosomal rearrangements and sex determination. This study investigated the occurrence and organization of repetitive DNA sequences in Leporinus elongatus using restriction enzyme digestion and the mapping of sequences by chromosomal fluorescence in situ hybridization (FISH). A 378-bp fragment with a 54.2% GC content was isolated after digestion with the SmaI restriction enzyme. BLASTN search found no similarity with previously described sequences, so this repetitive sequence was named LeSmaI. FISH experiments were conducted using L. elongatus and other Anostomidae species, i.e. L. macrocephalus, L. obtusidens, L. striatus, L. lacustris, L. friderici, Schizodon borellii, S. isognathus, and Abramites hypselonotus which detected signals that were unique to male and female L. elongatus individuals. Double-FISH using LeSmaI and 18S rDNA showed that LeSmaI was located in a nucleolus organizer region (NOR) in the male and female metaphases of L. elongatus. This report also discusses the role of repetitive DNA associated with NORs in the diversification of Anostomidae species karyotypes.

Influence of the traditional Brazilian drink Ilex paraguariensis tea on glucose homeostasis.

In this study we examined the acute in vivo effect and short- and long-term in vitro effects of samples from native and commercial Ilex paraguariensis on glucose homeostasis. Also, the potential effect of I. paraguariensis on serum insulin secretion was investigated. The chemical identification and quantification of methyl xanthines and polyphenols in CH2Cl2, EtOAc and n-BuOH fractions of native I. paraguariensis as well as infusions of green and roasted I. paraguariensis from a commercial source was verified by high-performance liquid chromatography. The results for the serum glucose-lowering indicated that both fractions and both infusions were able to improve significantly the oral glucose tolerance curve. Additionally, both the EtOAc and n-BuOH fractions induced-insulin secretion, but EtOAc induced an early (at 15 min) and late (at 60 min) biphasic peak of insulin secretion similar to glipizide stimulatory effect. Both fractions increased liver glycogen content compared with fasted normal rats. Also, EtOAc and n-BuOH fractions inhibited in vitro disaccharidases activities after an acute treatment. The maximum inhibitory effect of the EtOAc and n-BuOH fractions on maltase activity (at 5 min) was around 35%. The evident reduction of protein glycation by glucose or fructose with EtOAc and n-BuOH fractions increased from 7 to 28 days of in vitro incubation. Inhibition of bovine serum albumin glycation by glucose and fructose, by around 50% and 90%, respectively, was observed. Additionally, the green and roasted mate infusions reduced the formation of AGEs in a characteristic long-term effect. In conclusion, this study shows that I. paraguariensis has an anti-hyperglycemic potential role able to improve the diabetic status and is probably a source of multiple hypoglycemic compounds.

Factors associated with oxidative stress in women with breast cancer.

OBJECTIVE: To assess the association between physiological, physical, lifestyle and nutritional variables and oxidative stress biomarkers in women with breast cancer. METHODS: This cross-sectional study was conducted on 55 women newly diagnosed with breast cancer. The extent of oxidative stress was analyzed by the measurement of plasma lipid hydroperoxides (LH), thiobarbituric acid reactive substances (TBARS), protein carbonyl, whole blood reduced glutathione (GSH) and serum antioxidant capacity (AC). Diet data were obtained from food frequency questionnaire. Linear regression was used to determine the association between the variables studied and oxidative stress biomarkers. The protein carbonyl data was not included in the linear regression analyses since the data did not show a normal distribution, even after logarithmic and other transformations. RESULTS: After adjusting for energy intake, the intake of chicken and high-fat dairy products was associated with increased levels of LH, while vitamin E intake was associated with decreased LH levels (R² = 23.8%). Intake of oils was associated with increased levels of TBARS (R² = 6.82%). Positive axillary lymph node status was associated with decreased levels of GSH (R² = 9.31%). Increasing age was directly associated with levels of AC, while animal fat, dairy product, and sweet food intakes were associated with low levels of AC (R² = 41.42%). CONCLUSION: Intake of chicken, vitamin E, dairy products (particularly high-fat dairy products), oils, animal fat, and sweet foods, along with axillary lymph node status and age, may be important determinants of oxidative stress in women with breast cancer.

Dietary intake and oxidative stress in breast cancer: before and after treatments.

OBJECTIVE: The aim of this study was to investigate changes in dietary intake, anthropometric parameters and markers of oxidative stress in 40 women who underwent surgery, chemotherapy or radiation therapy for breast cancer. METHODS: Pretreatment and post-treatment measurements included data collected through a food frequency questionnaire, weight and height to calculate the body mass index (BMI) and oxidative stress markers assessed from blood reduced glutathione (GSH), serum antioxidant capacity (AC), plasma thiobarbituric acid reactive substances (TBARS), serum lipid hydroperoxides (LH) and plasma carbonyls. Differences were compared using paired Student's t-test or paired Wilcoxon's test. RESULTS: A significant increase (P < 0.05) in the intake of the food groups: meat and eggs, dairy products, beans, oils and fats, as well as food from the subgroups: red meat, milk and other dairy products rich in fat, fruit rich in vitamin C and vegetable fats was found after treatments. There was a significant increase in body weight (P < 0.05), BMI (P < 0.05), levels of TBARS (P < 0.0001), LH (P < 0.005) and carbonyls (P < 0.0001) and a significant decrease of levels of AC (P < 0.005) and GSH (P < 0.0001). CONCLUSION: Breast cancer diagnosis and treatments were associated with dietary intake changes and increased body weight, BMI and oxidative stress. These potential changes have important implications for preventive nutrition counseling.

Inhibitory effect of flavonoids on low-density lipoprotein peroxidation catalyzed by mammalian 15-lipoxygenase.

Lipoxygenase-dependent low-density lipoprotein (LDL) oxidation is believed to be involved in atherogenesis. Inhibition of lipoxygenase-induced lipid peroxidation might, therefore, be an important mode to suppress the development of atherosclerosis. Because dietary antioxidants inhibit LDL oxidation in vitro and their intake is inversely associated with coronary heart diseases, we compared the inhibitory effect of three typical flavonoids-quercetin, epicatechin, and flavone-with alpha-tocopherol and ascorbic acid against human LDL oxidation catalyzed by mammalian 15-lipoxygenase. The oxidative modification of LDL was monitored by measurement of cholesteryl ester hydroperoxide (CE-OOH) formation and consumption of antioxidants by using HLPC. Quercetin and epicatechin were the strongest inhibitors of LDL oxidation catalyzed by 15-lipoxygenase; ascorbic acid was an effective inhibitor in the first 3 h of oxidation; and fivefold alpha-tocopherol-enriched LDL showed a partial inhibition of CE-OOH formation only after 4-6 h of incubation. Flavone had no effect. Quercetin, ascorbic acid, and alpha-tocopherol were consumed in the first 3 h of incubation. Consumption of LDL alpha-tocopherol was partially inhibited by ascorbic acid and quercetin, whereas epicatechin and flavone were without effect. These results emphasize the inhibitory effect of the flavonoids quercetin and epicatechin on 15-lipoxygenase-mediated LDL lipid peroxidation. At similar concentrations, they are stronger antioxidants than ascorbic acid, alpha-tocopherol, and flavone.

Increased metabolism of peroxynitrite-modified [125I] beta-VLDL by monocytes from hypercholesterolemic rabbits.

The metabolism (uptake and degradation) of peroxynitrite-modified beta-VLDL and native beta-VLDL labeled with [125I]iodine was studied in monocytes isolated from peripheral blood of hypercholesterolemic (HC) and normolipidemic rabbits (NC). The peroxynitrite-modified beta-VLDL uptake and degradation was up to 2-fold higher in monocytes from HC rabbits than monocytes from NC rabbits. In addition, monocytes from HC rabbits took up and degraded significantly more peroxynitrite-modified beta-VLDL than native beta-VLDL. In contrast, monocytes from NC rabbits took up both lipoproteins in a similar rate and degraded more native beta-VLDL than peroxynitrite-modified beta-VLDL. Our results suggest that hypercholesterolemia can affect monocyte metabolism enhancing foam cell formation by increasing the influx of peroxynitrite-modified beta-VLDL.

Quercetin metabolites inhibit copper ion-induced lipid peroxidation in rat plasma.

The oxidative susceptibility of plasma obtained from rats after intragastric administration of quercetin was studied to know whether or not quercetin acts as an in vivo antioxidant after metabolic conversion. Quercetin was raised in the rat blood plasma essentially as glucuronide and/or sulfate conjugates. The plasma obtained from rats after quercetin administration was more resistant against copper sulfate-induced lipid peroxidation than the control plasma on the basis of the accumulation of cholesteryl ester hydroperoxides and the consumption of alpha-tocopherol. The results strongly suggest that some conjugated metabolites of quercetin act as effective antioxidants when plasma is subject to metal ion-induced lipid peroxidation.

Enhancement of antioxidative ability of rat plasma by oral administration of (-)-epicatechin.

To check whether ingestion of (-)-epicatechin (EC) affects the antioxidative defense in blood plasma, we studied the oxidizability of plasma from Wistar rats after intragastrical EC administration at 10 or 50 mg/rat. The plasma pool obtained from control or EC-administered rats was oxidized with copper sulfate or 2,2'-azobis(2-amidinopropane)dihydrochloride (AAPH). EC metabolites in plasma 1 h after EC administration contained glucuronide and glucuronide-sulfate conjugates in both the free and O-methylated form. After 6 h, the plasma concentration of total EC metabolites decreased and the remaining conjugates were mostly present as the O-methylated form. Compared to the control group, the plasma obtained from rats 1 and 6 h after EC administration was more resistant against copper sulfate-induced oxidation on the basis of cholesteryl ester hydroperoxide (CE-OOH) accumulation. Also, the consumption of alpha-tocopherol during oxidation was suppressed in the plasma obtained from EC-treated rats. The content of CE-OOH and consumption of alpha-tocopherol in the plasma from EC-administered animals was much lower than those expected from the amount of nonmetabolized EC present in the plasma. Similar results were obtained from AAPH-induced oxidation of rat plasma after EC administration, except for the fact that CE-OOH accumulation was less suppressed in the plasma 6 h following administration. The O-methylated form was found to be more stable than the free form when EC-administered rat plasma was auto-oxidized at 37 degrees. These results suggest that EC metabolites, particularly conjugates in the free form, possess an effective antioxidative activity in blood plasma.

Cholera in north Brazil: on the occurrence of strains of Vibrio cholerae O1 which fail to ferment sucrose during routine plating on thiosulphate-citrate-bile salt-sucrose agar (TCBS). A new problem in diagnosis and control?

The occurrence is recorded from a biochemical strain variant of Vibrio cholerae O1 originating from the municipality of Oiapoque, Amapá State, north Brazil and responsible for an epidemic outbreak of cholera in that region in August, 1994. The principal characteristic of the strain is its incapacity of break down sucrose on T.C.B.S. agar plates, and its delayed utilization of that sugar only after 48 hs. when cultivated in liquid medium. The strain spread rapidly in north Brazil, becoming responsible for most of the cases of cholera reported in Amazonian Brazil. The importance of this observation in laboratory diagnosis and the control of cholera is discussed.

Coriadienin, the first annonaceous acetogenin with two double bonds isolated from Annona coriaceae.

A new Annonaceous acetogenin, coriadienin (1), has been isolated from the roots of Annona coriacea Mart. (Annonaceae). This structure is the first reported acetogenin containing two double bonds. Compound 1 showed potent cytotoxicity against VERO and KB cell lines. Compound 1 appears to play an important role in the biosynthetic pathway of mono- and bis-THF acetogenins, and it is proposed as a biogenetic precursor of coriacin. A known cytotoxic acetogenin, gigantetronenin, was also isolated from this plant.