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PubMed1989

The synthesis of glutathione peroxidase analogs.

While it is recognized that oxidation has a major role in the development of cataract, few compounds have been developed which effectively reduce the potential for oxidative insult. A major oxidant confronting the lens is H2O2. Few compounds capable of metabolizing H2O2 have been synthesized. This communication reports that a number of compounds with glutathione peroxidase activity have been developed. Some of these compounds are 10 fold more active than Ebselen, previously recognized as the synthetic compound with the greatest GSH peroxidase activity.

Azoles↗
PubMed1989

Selenalysine transamination by a bovine brain enzyme.

Selenalysine is deaminated by glutamine transaminase from bovine brain, leading to the production of the corresponding alpha-ketoacid, which spontaneously cyclizes to a ketimine form. Selenalysine shows a good affinity for the enzyme.

Animals↗
PubMed1989

Studies of safe maximal daily dietary Se-intake in a seleniferous area in China. Part II: Relation between Se-intake and the manifestation of clinical signs and certain biochemical alterations in blood and urine.

Selenosis occurs in areas of Enshi county because of the high Se content of the food. Morphological changes in finger-nails were used as the main criterion for clinical diagnosis of selenosis. Pathological nails were observed to occur almost only in adults, not at all in young children and very seldom in teenagers. Symptoms of selenosis in susceptible patients were found at or above an Se-intake of 910 micrograms/d, corresponding to a blood Se level of 1.05 mg/L. There was no evidence for an increased susceptibility to dental caries due to high Se consumption, and an increase in Se-intake seems unlikely to reduce the beneficial effects of fluoride on caries. No abnormalities of liver or heart were seen by supersonic B or electrocardiographic examinations. The biochemical investigations showed that with increasing whole blood Se the ratio of plasma Se to erythrocyte Se tended to decrease. As Se-intake increases to over 750 micrograms daily, the ratio decreases to near a minimal level. Reduced glutathione in whole blood decreases within a blood Se range of 1.01 to 2.28 micrograms in the high Se area. The amount of trimethylselenonium ion excreted in urine increased with the increase of urinary Se. Cases with prolonged prothrombin time occurred as blood Se increased to a level above 1 mg/L. The white blood cell count also increased significantly. Quantitative values were obtained only for ratio of plasma-Se to erythrocyte-Se for prothrombin time and for maintenance of nail Symptoms of susceptible patients. The overall results indicated that a daily Se-intake of 750-850 micrograms [corrected] might be the marginal level of safe intake. When other variable factors are also taken into consideration a daily Se-intake of 400 micrograms [corrected] is suggested as the maximum daily safe intake. At this level of Se-intake the corresponding approximate tissue Se levels are: whole blood 0.559 mg/L, plasma 0.327 mg/L, urine excretion 173 micrograms/d, hair 3.60 mg/kg, toe-nails 4.25 mg/kg, and finger-nails 4.70 mg/kg.

Anemia↗
PubMed1989

[Protection from anoxic myocardial injury in fetal mouse heart culture by selenium].

Fetal hearts taken from the 17 day pregnant mice were cultured in minimum essential medium (MEM) + 0.5 ug ml of Na2SeO, and in MEM alone with oxygen for 24 h, and then the hearts in groups were exposed to 15, 20, 30, 40 min, 1 h, 3h and long term of anoxia respectively. The results showed that the survival and beating of the cultured fetal mouse hearts with anoxia were prolonged by selenium. Using lanthanum as a marker, we found that after 20 min of anoxia, this electroopaque marker remained extracellular in the selenium-treated hearts, however, intracellular lanthanum could be found in the control hearts, entering selectively into the swelling mitochondria. During the same period of anoxia, ACPase reaction products could be only found in the lysosomes and in the Golgi complex in the selenium-treated hearts, but a lot of reaction products deposited in cytoplasm in the control hearts. By electron microscopy, at 40 min of anoxia, there were swelling of mitochondria, with cristae partially lost and plasma-membrane changed and so on. Generally normal ultrastructure was observed in the selenium-treated hearts at 40 min of anoxia. The cytoplasm was rich in ribosomes and the sarcoplasmic reticulum with a rough face. There events showed that cellular membrane and membrane-bound organelles appeared to be well protected target by the selenium. Therefore, selenium may play an important role in the synthesis of protein.

Animals↗
PubMed1979

The effects of subcutaneous injections of sodium selenate on blood composition and milk yield in dairy cows.

Three groups of four lactating cows received a subcutaneous injection of 0 . 05, 0 . 10 and 0 . 15 mg Se/kg body weighty respectively administered as sodium selenate. A fourth group was injected with saline. In all the cows injected with sodium selenate, the concentration of Se in blood increased rapidly and was significantly higher than in control cows for two days in the group receiving the lowest dose and for 182 days (the duration of the experiment) in the two other groups. The activity of glutathione peroxidase in blood increased slowly in all cows injected with sodium selenate and was significantly greater than in control cows after 15, 22 and 29 days respectively, and remained significantly greater for 63, 91 and 182 days respectively. In a second experiment a single subcutaneous injection of 0 . 15 mg Se/kg body weight had no effect on the mean milk yield of 37 animals (19 . 1 kg/day) compared with the milk yield of a similar group of control animals (19 . 1 kg/day) during 70 days. The concentration of Se in milk was significantly higher on the first (168 microgram/litre) and second (69 microgram/litre) day after injection than in control animals (mean 26 microgram/litre).

Animals↗
PubMed1989

Toxicosis in pigs fed selenium-accumulating Astragalus plant species or sodium selenate.

Three groups of 5 pigs each were fed a high selenium (Se) diet by mixing either Astragalus praelongus (31.6 ppm Se in feed), A bisulcatus (31.7 ppm Se in feed), or sodium selenate (26.6 ppm Se in feed) with commercial hog feed. Ten control pigs were fed only commercial hog chow containing trace selenium (0.44 ppm Se). Pigs were fed for 9 weeks and necropsied when they had ataxia or paralysis. Blood was collected for hematologic and serum biochemical determinations, and samples of various tissues were collected and fixed in neutral-buffered 10% formalin for histologic evaluation or frozen for determination of selenium concentration. All forms of selenium induced clinical signs of weight and hair loss, with cracked hooves and inflamed coronary bands developing in all Na2SeO4-fed pigs and 1 A praelongus-fed pig, but not in A bisulcatus-fed pigs. Serum calcium, phosphorus, and albumin concentrations were unchanged or significantly decreased from prefeeding values in groups fed selenium. Serum aspartate transaminase (AST) activities in Astragalus species-fed groups, and amylase activities and PCV in all groups of pigs fed selenium, were increased. Serum alkaline phosphatase and creatine kinase activities were significantly increased in the A praelongus-fed pigs and significantly decreased in Na2SeO4-fed pigs. Terminal tissue and body fluid selenium concentrations were determined in all groups of pigs fed selenium and compared with values in control pigs. Urine and bile concentrations were increased by the greatest factor (40 to 100x), with tissue concentrations of selenium increased by a lesser factor (6 to 17x).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Antifungal effects of selenocystine and its derivatives on dermatophytes.

Antifungal effects of DL-selenocystine and its derivatives (DL-selenolanthionine, DL-Se-sulfoselenocysteine) and of sodium selenite were tested in 14 dermatophytes and 7 species of keratinolytic and non-keratinolytic soil fungi. Minimal inhibitory concentrations of the compounds were measured and compared to those of ketoconazole. Organic selenocompounds behaved similarly. They were on average less inhibitory than ketoconazole but, in some cases, MICs were equal or even lower. The effects of selenite were but small. The action of selenocystine and ketoconazole in concentrations up to 50 micrograms/ml was found to be mostly fungistatic. Free L-cystine (100 micrograms/ml) antagonized the antifungal effect of its selenoanalog.

Antifungal Agents↗
PubMed1985

[Effect of sodium selenite on the antitumor function of spleen lymphocytes in mice].

Sodium selenite in drinking water (1 ppm) was given to normal and hepatoma-bearing mice for 14 days. Spleen lymphocytes were incubated with hepatoma cells and 3H-TdR incorporation was measured. Sodium selenite increased the ability of spleen cells to inhibit 3H-TdR incorporation into hepatoma cells by more than 40%. In the meantime, in the spleen lymphocytes of normal and hepatoma-bearing mice, the activities of ATPase, acid phosphatase and alkaline phosphatase were definitely higher than that of the control (ATPase increased by 35.5% and 65.0%; acid phosphatase increased by 113.0% and 93.0%; alkaline phosphatase by 64.7% and 69.0%, respectively). These results suggest that sodium selenite (1 ppm), like immunologic stimulator such as bacillus Calmette Guérin (BCG), be able to stimulate the immunologic function of organism against hepatoma.

Acid Phosphatase↗
PubMedDate not supplied

Studies on recognition of selenahomolysine by aminoacid transport systems and aminocyl-tRNA synthetase.

In E. coli, Se-3 aminopropylselenocysteine or selenahomolysine (SeHL) does not affect intracellular lysine transport, i.e. it cannot bind E. coli lysine transport systems. In CHO cells it inhibits cationic aminoacid transport system, but only in the presence of Na+, this indicating that it behaves like polar neutral aminoacids. On the other hand, it poorly affects leucine transport both in the presence and in the absence of Na+. SeHL is not activated by aminoacyl-tRNA synthetase preparations from bacterial and mammalian sources, thus it cannot be utilized for protein synthesis.

Amino Acids↗
PubMed1988

Degradation of thialysine- or selenalysine-containing abnormal proteins in E. coli.

Thialysine and selenalysine can be utilized for protein synthesis by lysine-requiring E. coli cells even in the absence of lysine. Protein synthesis has been determined as labeled leucine incorporation into acid-insoluble material, as increase of cell proteins and as protein-lysine substitution by the analog. Either analog can be incorporated into proteins, in the absence of lysine, for a limited time interval after which cells stop to duplicate. Proteins synthesized during this period contain most of their lysine residues substituted by the analog. Moreover, it has been shown that the analog-containing proteins are unstable and rapidly degraded. Their instability would account for the inability of lysine-requiring E. coli cells to utilize the analog as growth factor.

Bacterial Proteins↗
PubMed1988

Utilization of lysine analogs by a lysine-requiring E. coli mutant.

Thialysine and selenalysine cannot substitute lysine as a growth factor for a lysine-requiring E. coli mutant, but can nevertheless be utilized for protein synthesis in the presence of lysine. In order to have information about the effects of lysine on the utilization of the two analogs, the extent of the incorporation of the three aminoacids into newly synthesized proteins has been determined. The analog starts to be utilized by cells growing in a medium containing either analog and lysine when lysine concentration becomes very low. Of the two analogs, thialysine is more easily utilized. In fact thialysine can be utilized when the lysine/thialysine ratio in the medium is 1/25. Selenalysine starts to be utilized when the lysine/selenalysine ratio is 1/200.

Cysteine↗
PubMed1987

[Effect of sodium selenite on the chromosomal aberration of V 79 cells induced in vitro by MNNG and MNU].

Effect of sodium selenite on chromosomal aberration of V 79 cells induced by MNNG and MNU was studied. Na2SeO3 alone, at the concentration of 10(-7)-10(-4) M, increased the incidence of chromosomal aberration. However, Na2SeO3 at 10(-7)-10(-5) M, having been preincubated with the cells for 4 hours, could reduce the number of cells with chromosomal aberration induced by MNNG. Na2SeO3 at 10(-7)-10(-4) M inhibited mutagenic activity of chromosomal aberration induced by MNU. The same inhibition was observed even sodium selenite was added to the medium simultaneously with this carcinogen. The results indicate that sodium selenite alone, at the concentration range used in this experiment, is an aberration-inducing agent. But when combined with the carcinogen, anti-cancer effect is obtained.

Animals↗