Effects of dietary selenium and vitamin E on hepatic mixed-function oxidase activities and in vivo covalent binding of aflatoxin B1 in rats

Male weanling fischer-344 rats were fed a selenium (Se)-vitamin E (VE) deficient Torula yeast basal diet or that diet supplemented with a graded levels of SE (0.2-6.0 ppm as Na2SeO3) or VE (100 iu/kg as all-rac-2-tocopheryl acetate), or both, for 4 or 6 weeks. Se deficiency and excess (6.0 ppm) markedly depressed in vivo covalent binding of aflatoxin (AFB1) to macromolecules in livers of rats killed 2 hours after an i.p. dose of 1 mg/kg tritiated AFB1. VE supplementation had no effect. Prior phenobarbital (PB) treatment generally decreased adducts without changing diet-related trends. Some hepatic enzyme capabilities were also measured. Cytochrome b5 content and cytochrome c reductase activity were unaffected by diet. VE increased cytochrome P-450 content, ethylmorphine N-demethylase and benz(alpha)pyrene hydroxylase activities; all these were unaffected by Se levels. Se deficiency and excess (but not VE deficiency) increased glucuronyl transferase. PB induction affected all diet groups and was more in agreement with MFO activity than transferase. Adduct formation was more consistently related to transferase activity than to MFO activities. The contrasting effects of SE and VE on AFB1 adducts in rats and chicks are discussed.

Bilirubin interactions with phospholipid components of lung surfactant

This work examines the dynamic surface pressure-area behavior of films of unconjugated bilirubin spread from chloroform solution at 22 degrees C on 0.15 M NaCl and buffered phosphate subphases. Film behavior is examined at pH 5.5, 7.4 and 8.0. The interactions of bilirubin in mixed films with dipalmitoyl phosphatidylcholine and with 9:1 dipalmitoyl phosphatidylcholine:dioleolyl phosphatidylcholine are examined at similar temperature and pH values. It is found that unconjugated bilirubin modifies the dynamic surface pressure-area behavior of phospholipid films in both the high and low surface pressure regimes, with bilirubin exerting its greatest effect at low pH where its subphase solubility is low. Because many premature infants suffering from the Respiratory Distress Syndrome (RDS) have accompanying hyperbilirubinemia, with possible bilirubin transport to the alveolar space, the interactions of bilirubin with phospholipid films are discussed in terms of potential effects on pulmonary surfactant in vivo.

Variant von Willebrand's disease and pregnancy

The clinical course and coagulation profile of a pregnant patient with variant von Willebrand's disease were followed from the second trimester through puerperium. The clinical course was characterized by a normal delivery and absence of abnormal bleeding or need for replacement therapy. The coagulation profile demonstrated an increase in factor VIII procoagulant activity, factor-VIII-related antigen, and platelet aggregation activity in response to ristocetin prior to delivery. Postpartum, these factors decreased to prepregnancy values with distinctly different patterns. Factor VIII procoagulant activity continued to rise for 5 days after delivery and then decreased with a half-life of approximately 6 days. Factor-VIII-related antigen began to decrease just prior to delivery, displaying a half-life or approximately 6 days. Ristocetin cofactor activity, however, dropped immediately postpartum and displayed a half-life of approximately 6 hr. The ristocetin cofactor activity was associated with factor-VIII-related antigen, which displayed a significantly smaller molecular weight than does normal factor-VIII-related antigen. Larger aggregates of factor-VIII-related antigen. Larger aggregates of factor-VIII-related antigen did not appear during the pregnancy, and ristocetin cofactor activity could not be demonstrated in fragments of less than 0,8 x 10(6).

Expression of storage-protein genes during soybean seed development

Mature seeds of Glycine max (L.) Merr. contain two major storage proteins, a glycosylated 7S protein (conglycinin) and a non-glycosylated 11S protein (glycinin). Accumulation of these proteins and their mRNAs during seed development in cv. Provar was studied by SDS polyacrylamide gel electrophoresis and by "Northern" (DNA-RNA) hybridization. The 11S acidic and basic subunits and the 7S α' and α subunits began to accumulate 18-20 d after pollination, shortly after the termination of cell division in developing cotyledons, whereas the 7S β and 11S A-4 subunits were not detected until one to two weeks later, during the maturation phase of development. Messenger RNAs for 7S and 11S proteins were first detected 14-18 d after pollination, several days before the accumulation of storage proteins. Extracts from embryonic axes contained reduced levels of the 7S α subunit, very little 11S protein, no detectable 7S β or 11S A-4 subunits, and an additional 7S subunit not found in cotyledons. Soybean axes and cotyledons therefore differ in their synthesis of seed storage proteins.

Dihydromevinolin, a potent hypocholesterolemic metabolite produced by Aspergillus terreus

A new, potent hypocholesterolemic agent is produced by cultures of Aspergillus terreus. The isolation of the compound and its characterization as 4a,5-dihydromevinolin containing a trans-fused octahydro-naphthalene system are described. Comparative data for dihydromevinolin and mevinolin in three biological assays are given: in vitro inhibition of HMG-CoA reductase, inhibition of sterol synthesis in cell cultures, and inhibition of cholesterol synthesis in vivo in rats.

Subunit characterization of lens intermediate filaments

The intermediate filaments from the bovine ocular lens can be fractionated into three 54000 dalton polypeptides (alpha, beta and gamma) which are present in equimolar quantities and differ from one another with respect to isoelectric point, two-dimensional peptide map pattern and total amino acid composition. The polypeptides, for which the name lentin is proposed, were purified from the 8 M urea extract of the water-insoluble residue of the cortical fiber cells by ion-exchange chromatography on DE- and CM-cellulose. The regeneration of native-appearance filaments from each purified fraction, or combinations thereof, definitively established the three polypeptides as the subunit species. Additionally, small diameter 'protofilaments' were regenerated when one or two fractions were utilized, but not when all three fractions were combined. This, together with the fact that the stoichiometric yield of the three species was invariably equimolar, suggests that alpha, beta, and gamma may be distinct entities not related by artifactual interconversion.

Mevinolin: a highly potent competitive inhibitor of hydroxymethylglutaryl-coenzyme A reductase and a cholesterol-lowering agent

Mevinolin, a fungal metabolite, was isolated from cultures of Aspergillus terreus. The structure and absolute configuration of mevinolini and its open acid form, mevinolinic acid, were determined by a combination of physical techniques. Mevinolin was shown to be 1,2,6,7,8,8a-hexahydro-beta, delta-dihydroxy-2,6-dimethyl-8-(2-methyl-1-oxobutoxy)-1-naphthalene-hepatanoic acid delta-lactone. Mevinolin in the hydroxy-acid form, mevinolinic acid, is a potent competitive inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A reductase [mevalonate: NADP+ oxidoreductase (CoA-acylating), EC 1.1.1.34]; its Ki of 0.6 nM can be compared to 1.4 nM for the hydroxy acid form of the previously described related inhibitor, ML-236B (compactin, 6-demethylmevinolin). In the rat, orally administered sodium mevinolinate was an active inhibitor of cholesterol synthesis in an acute assay (50% inhibitory dose = 46 microgram/kg). Furthermore, it was shown that mevinolin was an orally active cholesterol-lowering agent in the dog. Treatment of dogs for 3 weeks with mevinolin at 8 mg/kg per day resulted in a 29.3 +/- 2.5% lowering of plasma cholesterol.

Studies on the relations of selenium and Keshan disease

Keshan disease is an endemic cardiomyopathy of unknown cause in The People's Republic of China that occurs most frequently in children under 15 years of age and women of child-bearing age. Studies of children 1-9 years old in Mianing County of Sichuan Province have indicated that Keshan disease is a selenium responsive condition. Incidence rates of 9.5-13.5/1000 in 1974-1975 were reduced to 1-2/1000 in children treated with a tablet weekly of 0.5-1 mg sodium selenite. During 1974-1977, only 21 cases of the disease occurred in 36,603 treated children, compared with 106 cases in 9430 untreated children, of whom 53 died and 5 still have insufficient heart function. Occurrence of the disease was invariably associated with a lower selenium content of cereals, and of hair (less than 0.12 ppm Se) in residents from affected, compared with non-affected, areas. The dose relationship between selenium and regional characteristics of Keshan disease suggests that it is probably a biogeochemical disease; other etiological factors have also been considered.

Significance of "high" acid phosphatase activity in the serum of normal children

Serum acid phosphatase activity in normal children (newborn to 18 years) is several fold that in normal adults. Activity is age-related but not sex-related. The isoenzyme pattern in children is similar to that in adults and contains no prostatic fraction. Quantitatively, most of the enzyme activity in the serum of children is tartrate-resistant and correlates well with heat-labile fractions of alkaline phosphatase activity in serum, suggesting that the source of the higher acid phosphatase activity in children is bone. Significant tartrate-resistant acid phosphatase activity was demonstrated in the giant cells in three patients with giant-cell tumors, but not in the "osteoblasts" in six patients with osteogenic sarcomas and many other normal or abnormal tissues. This work suggests that the higher enzyme activity in the serum of children represents a normal physiological phenomenon resulting from their greater osteoclastic activity.

Significance of "high" acid phosphatase activity in the serum of normal children

Serum acid phosphatase activity in normal children (newborn to 18 years) is several fold that in normal adults. Activity is age-related but not sex-related. The isoenzyme pattern in children is similar to that in adults and contains no prostatic fraction. Quantitatively, most of the enzyme activity in the serum of children is tartrate-resistant and correlates well with heat-labile fractions of alkaline phosphatase activity in serum, suggesting that the source of the higher acid phosphatase activity in children is bone. Significant tartrate-resistant acid phosphatase activity was demonstrated in the giant cells in three patients with giant-cell tumors, but not in the "osteoblasts" in six patients with osteogenic sarcomas and many other normal or abnormal tissues. This work suggests that the higher enzyme activity in the serum of children represents a normal physiological phenomenon resulting from their greater osteoclastic activity.

Study of a Caucasian Family with von Willebrand’s Disease in Association with Vascular Telangiectasia and Hemoglobinopathy

This family carries multihematological inherited disorders; namely, von Wille-brand’s, vascular telangiectasia and hemoglobinopathy. Family members were studied by quantifying the following: Factor VIII pro-coagulant activity, Factor VIII related antigen, Factor VIII inhibitors, platelet adhesion, platelet aggregation (with ristocetin, collagen and ADP), bleeding time, platelet count, partial thromboplastin time, prothrombin time, hemoglobin electrophoresis, hemoglobin finger-printing, sickling preparation and the presence of telangiectasia.

The affected members of this family with von Willebrand’s express their disease in a variable tendency to bleeding from almost clinically asymptomatic cases to cases with severe bleeding tendency.One member of this family had to have a hysterectomy at the age of 20 to control the abnormal uterine bleeding after conservative treatment failed. All affected members with von Willebrand’s disease had a normal platelet count, prolonged bleeding time, decreased Factor VIII pro-coagulant activity and related antigen, negative aggregation using the ristocetin co-factor for von Willebrand’s, defective platelet adhesiveness to glass beads, and normal platelet aggregation to collagen and ADP. Some members have vascular telangiectasia in the mucous membranes. An incidental finding was the presence of an abnormal hemoglobin S in some family members.

Supported in part by the Cumberland Chapter of the National Hemophilia Foundation.

Translation of rat liver fatty acid synthetase mRNA in a cell-free system derived from wheat germ

Total liver polysomes were isolated from rats that had fasted for 48 hr and that then had been re-fed a high-carbohydrate, fat-free diet for 20-24 hr. Indirect immunoprecipitation of the polysomes with purified antibody to rat liver fatty acid synthetase and deproteination on sodium dodecyl sulfate-containing sucrose gradients gave an RNA fraction which, when translated in a cell-free system derived from wheat germ, yielded a major polypeptide of apparent molecular weight 225,000 when the translation products were analyzed by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. The polypeptide was specifically precipitated with antibody against rat liver fatty acid synthetase and competed with unlabeled fatty acid synthetase for binding to the antibody. It was somewhat smaller than native fatty acid synthetase subunits (molecular weight 240,000). The peptide accounted for approximately 65% of the radioactive, antibody-precipitable product, the remainder being peptides in the molecular weight range 100,000-150,000. Synthesis of the polypeptide was optimized with respect to K(+), Mg(2+), and spermine concentrations. The quantity of fatty acid synthetase mRNA obtained by the above procedure and measured by translation was a function of the nutritional state of the animal. The relative activity in fasting rats compared to rats that were re-fed for 12 hr was 1:12. The data suggest that rat liver fatty acid synthetase is synthesized as intact subunits from a large mRNA molecule or molecules.