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The objective of the present study was to assess the excretion of urinary thiol compounds in patients with active and inactive rheumatoid arthritis (RA). Urinary thiol compounds were measured by the method of Kokonov (M. T. Kokonov, Lab. Delo 5:273-276, 1965) in 51 outpatients with active and inactive RA. Those with active disease had significantly higher levels of urinary thioamine excretion.
Increased SeO32- concentration reduced H2S evolution from SO32- during whole cell and cell-free extract reductions by Clostridium pasteurianum. H2S production from SO42- was completely inhibited by SeO32- in stationary phase cells. Generation times increased with greater SeO32- concentration, the increase with 1 mM SeO32- being a factor of 2.5 for 1 mM SO32-, and over 3 for 1 mM SO42- reductions. In vitro and in vivo experiments with proposed intermediates of the SO32- reduction pathway show that SeO32- inhibited both the S3O62- to S2O32- and S2O32- to S2- reaction sequences with the latter being more pronounced in growth experiments. Both extracts and whole cells reduced SeO32- to Se0 but Se0 granules were not found in the cell's cytoplasm. The formation of S2O32- by an extracellular chemical mechanism appears not to have occurred in these experiments. Increased SeO32- concentration had the effect of compressing the isotopic release pattern for H2S along the H2S production axis and did not significantly alter the maximum and minimum values of delta 34S. Thus, inhibition by SeO32- limited the conversions of sulfur species without altering the isotopic selectivity of rate-controlling steps in the pathway.
Six piglets, aged 4 weeks (weaning) at the beginning of the experiment, were fed a diet lacking antioxidants (vitamin E and selenium) and enriched with oxidated cod liver oil (the peroxide value of which was 112.54 meqv/kg). Four of the experimental pigs were killed for necropsy at the age of 2 months and the remaining two pigs at the age of 3 months. Two piglets from the same litter served as controls. Myodegeneration of the skeletal muscles was induced in the experimental group. The livers were pale and mottled. Light microscopy revealed degenerative alterations in the heart and skeletal muscle and infiltrations by lipidic substances. The ultrastructure of some lipidic droplets was analogous to those of ceroid and lipofuscin. Peroxisomes were frequent in degenerating hepatocytes. In order to elucidate the lysosomal involvement in the residual formation, light and electron microscopical immunocytochemistry using copper-zinc superoxide dismutase (CuZnSOD), was applied. Probably zinc was recruited into the antioxidant protection concluding upon the increased erythrocyte superoxide dismutase (E-SOD) activity.
This manuscript reports the ready synthesis of high-quality colloidal CdSe nanocrystals from tri-n-octylphosphine (TOP) and reports the optical properties of the resulting CdSe dispersed in nonpolar and polar environments. With cadmium oxide (CdO) as the Cd precursor and TOPSe as the Se source, the CdSe nanocrystals were synthesized in a reaction medium consisting of TOP. The synthetic approach is as simple as: the swift injection of a TOPSe/TOP solution into a CdO/TOP solution at one particular (high) temperature, with subsequent growth at a lower temperature. The temporal evolution of the optical properties, including absorption and luminescence, were monitored in detail. The photoluminescence (PL) properties of the TOP-capped CdSe investigated comprise the intensity, emission peak wavelength, full width at half maximum of the PL spectra, and stability; these PL properties are sensitive to the history of growth as well as the environment of dispersion. An appropriate parameter, termed "Sensitivity Index (SI)," is proposed to define the percent difference in the PL intensity that arises when the dots are dispersed in non-polar hexane (Hex) as compared to polar tetrahydrofuran (THF). The decrease in the PL efficiency on going from Hex to THF is attributed to changes in surface states rather than in the internal core as more ligands are removed in THF. Dilution experiments further confirm the suggestion of the ligand removal mechanism and provide a conceptual estimate of surface quality via the SI parameter. Due to a slow growth in size (the size of the nanocrystals is almost constant during early 20 min) and good PL stability (tested as PL changes after storage for days both in dispersed or solid states, as well as after UV-irradiation), we suggest that our synthetic approach is likely to be practical for large-scale CdSe nanocrystals with good PL stability.
Colloidal CdSe nanocrystals were synthesized in reaction media consisting of tri-n-octylphosphine (TOP) without addition of other species; the single-step approach used cadmium oxide (CdO) and TOPSe as Cd and Se sources, respectively. The temporal evolution of the optical properties of the growing TOP-capped CdSe nanocrystals was monitored for a couple of hours, showing that there are two distinguishable stages of growth: an early stage (less than 5 minutes) and a later stage; the growth kinetics of the two stages is a function of the Cd-to-Se precursor molar ratios. A rational choice of 2-6Cd-to-1Se molar ratio was found, based on the temporal evolution of the photoluminescent (PL) efficiency (studied as PL intensity and sensitivity to the media of dispersion, and non-resonant Stokes shifts). For a 2Cd-to-1Se synthesis, the growth in size was slow in the early stages and became fast in the later stages; this fast-later-stage feature could be suppressed by going to a synthesis with a 4-6Cd-to-1Se mole ratio: the nanocrystals between 0.5-60 min growth time exhibit very much similar optical properties, with less than 19 nm redshift of bandgap absorption and emission occurring. Thus, the synthetic route developed here, with a rational 4-6Cd-to-1Se molar ratio, enables us to produce high-quality CdSe nanocrystals on a large-scale with a high degree of synthetic reproducibility. The insights gained facilitate a deeper understanding of the concept of what constitutes high-quality nano-crystals: high PL efficiency resulting from a low growth rate, which can be thoroughly and readily investigated by the red-shift rate of the band-gap peak positions; in addition, the insights gained help us to define a proper synthetic approach for large-scale production with high-quality product.
The Baeyer-Villiger (B. V.) reaction using SeO2-H2O2 was examined for various benzaldehydes possessing methoxy groups and/or a furan ring. When benzaldehydes have an electron-donating group (methoxy group) at the ortho or para position to a formyl group, the B. V. reaction proceeded rapidly and in a good yield. Since the reaction using SeO2-H2O2 is carried out under a neutral condition, this reaction are applicable to aldehyde derivatives with a furan ring which is unstable against acid.
DNA synthesis was evaluated in vitro by measuring incorporation of 3H-thymidine in rat lens following systemic delivery of a cataractogenic dose of selenite. Among early metabolic changes observed in the lenses of rats receiving a single dose of 30 nmol Na2SeO3/g body weight was a 30% decrease in DNA replication in lens epithelium occurring between 6 and 12 h after administration of the selenite. This change was followed by an 80% increase in replication by 24 h. Thymidine incorporation in DNA remained elevated compared to controls through 96 h. Unscheduled DNA synthesis was found to be approximately 10% of the total DNA formed, but there was a 30% and 70% increase of this putative DNA repair in the lenses from selenite-treated animals at 6 and 24 h after the injection. Using the alkaline unwinding assay, the proportion of single-strand DNA in lenses from selenite-treated animals increased after 24 h. This estimate of DNA damage was greater in lenses after 96 h. Each component of DNA metabolism: damage, repair, and replication, was affected by the occurrence of selenite stress in lens. These changes both preceded and accompanied nuclear cataract formation.
Two hours after suicidal ingestion of an unknown amount of selenium dioxide, a 17-year-old male was admitted to hospital with asystolia and apnea. Attempts at resuscitation failed and the patient was pronounced dead. Findings at autopsy included congestion of lungs and kidneys, diffuse swelling of the heart, and brain edema. The most impressive finding was an orange-brown discoloration of the skin and all viscera, probably due to hemolysis and/or pigmentation related to ingestion of selenium dioxide. Selenium blood and tissue levels were increased by a factor of 100-1000 as compared to normal. The highest concentrations were found in pancreas, spleen, liver, and adipose tissue. For elucidation of the chemical nature of selenium in tissues, a new analytical method which was based on carbon disulfide extraction was developed. Carbon disulfide is a good solvent for non-polar selenium compounds like elemental selenium and selenium disulfide, but not for polar compounds like selenite and selenoproteins. A major fraction of selenium in tissues was extractable by carbon disulfide, which seems to indicate the presence of elemental selenium and/or selenium disulfide. The color of these substances is red and orange, respectively. This might explain at least part of the discoloration of skin and tissues. In vitro experiments suggested that trace amounts of hydrogen selenide, which is an intermediate of selenite metabolism, probably induced hemolysis. For evaluation of the therapeutic value of hemoperfusion in selenium poisoning in vitro hemoperfusion experiments were performed, which revealed only a moderate effect on selenium blood levels.
Experiments were conducted to determine the effects of dietary protein level and level of feed intake on the apparent bioavailability of Se from Na2SeO3 and selenomethionine (DL-Se-Met) for protection from exudative diathesis (ED) of the Se- and vitamin E-depleted chick. Level of dietary protein (22.5 vs. 16.9%) significantly (P less than .01) affected the incidence of ED at several levels of dietary Se from each source. At each level of Se, the low protein diet resulted in a lower incidence of ED and, thus, an increase in the apparent bioavailability of Se; Se from Na2SeO3 was more available than that from Se-Met. Further experiments were conducted to determine whether the effect of dietary protein level on the incidence of ED was due to effects on growth rate or feed intake. Chicks were fed the high or low protein basal diets at 75% of ad libitum rate of feed consumption. Sodium selenite was added to make Se intakes equivalent, either on a per day or a per unit gain basis, to ad libitum feeding controls receiving the Se-supplemented diets. Results showed that both a low level of dietary protein and a restricted level of feeding markedly reduced the incidence and severity of ED. The activity of Se-dependent glutathione peroxidase (SeGSHpx) in plasma and liver varied inversely with the incidence of ED and was increased by feed restriction. These results suggest that growth rate affects both the clinical and biochemical manifestations of Se-deficiency in the chick. Because both parameters are used to assess the bioavailability of Se in feeds and foods, bioassays in which growth rate is different between test and reference treatments may yield incorrect results.
A new soil actinomycete (UC 5762, NRRL 11111) was found to transform novobiocin to 11-hydroxynovobiocin. The product was isolated by solvent extraction and column chromatography, and identified by IR, UV, 1H NMR and 13C NMR spectroscopy. Related structures (8,9-dihydronovobiocin, novobiocic acid and chlorobiocin) were similarly transformed to their corresponding C-11 hydroxylated analogues. The microbial process is superior to chemical (selenium dioxide) oxidation which yielded a mixture of 11-hydroxy- and 11-oxonovobiocin.
A series of novel 26-substituted milbemycin A4 derivatives was synthesized from 5-O-t-butyldimethylsilyl-26-hydroxymilbemycin A4 prepared by selenium dioxide oxidation of 5-O-t-butyldimethylsilyl-milbemycin A4. Their acaricidal activities were assessed against the organophosphorus-sensitive two-spotted spider mite (Tetranychus urticae) on the primary leaves of cowpea plants (Vigna sinesis Savi species) by spraying.
Malignancies have a distinguished role among leading causes of death around the world. As a result of more effective preventive efforts of cardiovascular diseases malignancies will reach the top of death statistics in the near future. The increased incidence of malignant tumors may be attributed to smoking, in temperate alcohol abuse, as well as inappropriate nutrition. Inappropriate nutrition is thought to be responsible for the development of about 30-50% of malignancies. In the present review the authors analyze the uniform theory of carcinogenesis and the possible mechanisms by which certain nutritive factors may interfere with the complex process of carcinogenesis. The mechanism of "oxidative stress" is detailed, in particular the impact of prooxidants (also referred to as free radicals) on tumor development and the central role of lipid peroxidation. In addition to alimentary free radicals the relevance of alcohol abuse in carcinogenesis is also studied. Against the undesirable free radical reactions a complex natural antioxidant (free radical scavenger) system exists, that is responsible for anticarcinogenesis. The authors introduce the dietary antioxidants, their known effects of mechanisms, and their possible role in chemoprevention and therapy of malignancies, based on several experimental and epidemiological data.
OBJECTIVE: To compare the effects of selenium-enriched garlic (Se-garlic), garlic, Na2SeO3, and garlic + Na2SeO3 on growth of human gastric carcinoma cells. METHODS: In vivo and in vitro assays were carried out in the cultured human gastric carcinoma cell line MGC803 transplanted in the nude mice by cell count, flow cytometry, Western blot and neoplasm volume measurement. RESULTS: The inhibition effect of garlic was similar to that of Se-garlic, but Na2SeO3 was weaker than Se-garlic. Combination of garlic and Na2SeO3 was stronger than Se-garlic. In flow cytometry assay, the proportion of G1 phase was increased after 24 hour treatment of Se-garlic, garlic and Na2SeO3 in the non-synchronized cells. However, the proportion of S phase was increased in the synchronized cells. The proportion of G2 + M phase was increased both in non-synchronized and synchronized cells on treatment with the combination of garlic and Na2SeO3. The amount of Cdk2-CyclinE complex and Cdk4-CyclinD1 complex was decreased in all treated synchronized cells in immunoprecipitation and immunoblot assays. The growth of MGC803 tumor in male Balb/c nude mice was inhibited by administration of 1.67% of Se-garlic (Se 2 micrograms/g) in diet with an inhibition rate of 29.92% in tumor weight. Treatment of either 0.83% of Se-garlic or 1.67% of garlic or 4.38 micrograms/g of Na2SeO3 (Se 2 micrograms/g) could not appreciably inhibit the growth of tumor. Wrapping of a number of monocytes around the tumor was induced in 62.50% of tumors in 0.83% of the Se-garlic group. CONCLUSION: In vitro, Se-garlic is able to inhibit the growth of MGC803 cell through action of garlic. In vivo, Segarlic is able to inhibit growth of MGC803 tumor in nude mice by being better than garlic and selenite.
BACKGROUND & OBJECTIVE: This study was designed to investigate the impact of selenium dioxide (SeO2) on regulatory regions P250 of c-fos gene and to seek possible regulation mechanism. METHODS: HeLa cells were transfected with plasmids containing upstream regulating regions of c-fos chloramphenicol acetyl-transferase (CAT). The cells were cultured in various concentration of selenium dioxide. CAT expression in transfected cells was observed. RESULTS: After transfected HeLa cells were exposed to selenium dioxide, CAT expression showed obvious increase, especially in 10 micromol/L and 30 micromol/L selenium dioxide group (P< 0.05). CONCLUSION: Trough affecting regulatory regions P250 of c-fos gene, Selenium dioxide plays biological effect of regulating tumor cells. Selenium dioxide possibly has anti-tumor effects.
BACKGROUND & OBJECTIVE: It was reported that selenium could induce apoptosis of cancer cells; moreover, apoptosis of cancer cells and telomerase activity were closely related to the development of cancer. This study was designed to investigate the effect of selenium dioxide on human pulmonary adenocarcinoma GLC-82 cell to reveal its probable mechanism and the relationship between apoptosis and telomerase activity. METHODS: Methyl thiazolyl tetrazolium(MTT) method was used to determine the growth inhibition rates of lung cancer GLC-82 cells by various concentrations of selenium dioxide at different time. TRAP-PCR-ELISA assay was used to examine the changes of GLC-82 cells treated with selenium dioxide. The cell apoptotic rate was measured by flow cytometry (FCM). DNA ladder was showed by DNA agarose gel electrophoresis. The morphological changes of the cancer cells were examined under light and electron microscope. RESULTS: After being treated with 3, 10, 30 micromol/L selenium dioxide, the proliferation and telomerase activity of GLC-82 cells were markedly inhibited. The growth inhibition rates in GLC-82 cells for 24 hours were 0.7%, 12.8%, and 31.8%; for 72 hours were 15.1%, 51.2%, and 61.1%, respectively. Telomerase activity of GLC-82 cells for 24 hours were 1.173+/-0.029,1.127+/-0.067, and 1.050+/-0.098(P< 0.05); for 48 hours were 1.150+/-0.026, 1.047+/-0.060, and 0.950+/-0.036(P< 0.05), respectively (control group: 1.227+/-0.032 and 1.167+/-0.023, respectively). An apoptosis peak appeared before diploid peak in FCM. Agarose gel electrophoresis showed overt ladder-shape band of cell apoptosis. GLC-82 cells treated by selenium dioxide showed morphological characteristics of apoptotic cells. CONCLUSION: Selenium dioxide could significantly inhibit the growth of lung cancer GLC-82 cells through inducing apoptosis and inhibiting the telomerase activity. Selenium dioxide has strong growth inhibitory effect in a dose-and time-dependent manner.
OBJECTIVE: To investigate the mechanisms underlying the effect of selenium dioxide (SeO(2)) on the proliferation, apoptosis, and apoptosis-related gene expressions of Bcl-2 and p53 in 3 leukemia cell lines NB4, K562 and HL-60. METHODS: The three leukemia cell lines were treated with 3, 10 and 30 mmol/L SeO(2) and apoptosis detected by flow cytometry and analysis of p53 and Bcl-2 expressions. RESULTS: SeO(2) at 10 and 30 mmol/L could inhibit the proliferation of three leukemia cell lines. SeO(2) treatment at 30 mmol/L for 48 h induced an apoptosis rate of 54.0 %, 46.5 %, 49.6 % in NB4, K562, and HL-60 cells respectively, and down-regulated Bcl-2 expression in NB4 and K562 but not in HL-60 cells. CONCLUSION: SeO(2) can induce apoptosis in NB4, K562 and HL-60 leukemia cells, involving the down-regulation of Bcl-2 and up-regulation of p53.
An ecological survey on diet, life style and cancer mortality was carried out in 65 rural counties in China, using a questionnaire comprising 285 questions on environmental factors, dietary practices and other life style characteristics; in addition, blood, urine and food were collected and analysed. Two interpretations of preliminary data are presented. One is for the finding of a positive correlation between a latent variable, namely general nutritional status, and cancer mortality rates; the other is for a positive correlation between lipid peroxidation (plasma lipid peroxidase and copper) and oesophageal and gastric cancer mortality, and a negative correlation between dietary oxidants (plasma selenium, ascorbic acid and retinol) and mortality from oesophageal and gastric cancer.
The toxicity of selenium (Na2SeO3) and mercury (HgCl2) was determined by using a freshwater planarian which is particularly sensitive to pollution, and belongs to a fissiparous breed of Dugesia gonocephala. The mortality and fissiparity frequency of the subjects were studied. They were exposed to intense treatments (48 hours) or for medium to long periods of time (21 days) to either the single compounds or a combination of both, and were fed or fasting. The lethal effect of sodium selenite is correlated to the food intake, whereas the toxicity of mercurous chloride is probably the result of a fixative effect which does not depend on feeding. The 21-day treatment with the first compound has a non-negligible lethal effect which is probably due to an accumulation phenomenon. At doses where an antioxidant effect prevails, fissiparity is stimulated. On the other hand, the second compound reduces reproduction frequency to half the base values. Compared to the Paracentrotus lividus, the Dugesia gonocephala offers various advantages concerning toxicological experiments; besides being easier to handle in the laboratory, it is available all year round and is not subject to seasonal cycles. It is also more susceptible to the toxic effect of mercury, which is a common and highly toxic pollutant, than the sea urchin.