Showing papers on "B vitamins published in 1991"
TL;DR: The cloned MAD-3 cDNA encodes an I kappa B-like protein that is likely to be involved in regulation of transcriptional responses to NF-kappa B, including adhesion-dependent pathways of monocyte activation.
695 citations
TL;DR: A systematic analysis of the temporal and functional relationships among the H, E, A, and B splicing complexes concluded that E complex commits pre-mRNA to the splicing pathway and that this step is critical in determining the efficiency of mammalian spliceosome assembly.
Abstract: Previous studies have identified five distinct mammalian splicing complexes that assemble on pre-mRNA in vitro. Of these complexes, which include H, E, A, B, and C, only the B and C complexes have been isolated and shown directly to be functional intermediates in the splicing pathway. In this report we carried out a systematic analysis of the temporal and functional relationships among the H, E, A, and B complexes. Using gel filtration to isolate each complex, we show that H complex, which consists primarily of hnRNP proteins, assembles first in either the presence or absence of ATP. Subsequently, E complex, which contains stably bound U1 snRNP, is detected in reactions lacking ATP, whereas A complex, which contains stably bound U1 and U2 snRNPs, is detected in reactions containing ATP. We show that E complex can be chased into A and B complexes and that A complex can be chased into B complex. Both E and A complexes can also be chased into spliced products. In contrast, H complex cannot be chased into A or B complexes or spliced products under the same conditions. We conclude that in addition to the two spliceosome complexes (B and C), two distinct pre-splicesome complexes (E and A) are functional intermediates in the splicing pathway. Comparison of the efficiency of splicesome assembly on different pre-mRNAs has revealed dramatic differences. We show that these differences are first apparent at the time of E complex assembly. Thus, we conclude that E complex commits pre-mRNA to the splicing pathway and that this step is critical in determining the efficiency of mammalian spliceosome assembly.
264 citations
TL;DR: It is shown here that the HIV-1 protease can process p105 and increases levels of active nuclear NF-κB complex, which is required for efficient transcription1 of the human immunodeficiency virus type-1 genome.
Abstract: Transcription of the human immunodeficiency virus type-1 (HIV-1) genome is regulated in part by cellular factors and is stimulated by activation of latently infected T cells. T-cell activation also correlates with the induction of the factor NF-kappa B which binds to two adjacent sites in the HIV-1 long terminal repeat. This factor consists of two DNA-binding subunits of relative molecular mass 50,000 (50K) associated with two 65K subunits. It is located in the nucleus in mature B cells, but is present in other cell types as an inactive cytoplasmic complex. External stimuli, including those that activate T cells, result in nuclear translocation of active NF-kappa B. The cloning of the complementary DNA for the 50K subunit helped to identify an exclusively cytoplasmic 105K precursor (p105) (V.B., P.K. and A.I., manuscript submitted). The expression of active NF-kappa B might therefore also be regulated by the extent of processing of p105. Because HIV-1 requires active NF-kappa B for efficient transcription, we tested the effect of HIV-1 infection on the processing of the human 105K precursor. We show here that the HIV-1 protease can process p105 and increases levels of active nuclear NF-kappa B complex.
162 citations
TL;DR: The product of the protooncogene c-rel is a constituent of an NF-kappa B-like complex that binds to the kappa B site originally identified in the enhancer of immunoglobulin kappa light chain gene.
Abstract: We show that the product of the protooncogene c-rel is a constituent of an NF-kappa B-like complex that binds to the kappa B site originally identified in the enhancer of immunoglobulin kappa light chain gene. c-rel protein synthesized in bacteria binds to the kappa B site in a sequence-specific manner. The rel-kappa B complex can be disrupted by incubation with anti-rel antibodies. The rel protein can form oligomers. The c-rel protein can activate transcription from promoters containing kappa B sites; v-rel, on the other hand, suppresses the transcription of genes linked to kappa B sites. Thus, v-rel may interfere with the normal transcriptional machinery of the cell by acting as a dominant negative mutant.
119 citations
TL;DR: The kinetic and crystallographic studies have been combined to provide rationalizations for the apparent affinities of glucose and the analogues and show the discrimination against beta-D-glucose is achieved by an additional hydrogen bond made in the alpha- glucose complex through water to a protein group and an unfavorable environment for a polar group in the beta pocket.
Abstract: The T-state crystal structure of the glucose-phosphorylase b complex has been used as a model for the design of glucose analogue inhibitors that may be effective in the regulation of blood glucose levels. Modeling studies indicated room for additional atoms attached at the C1-beta position of glucose and some scope for additional atoms at the C1-alpha position. Kinetic parameters were determined for alpha-D-glucose: Ki = 1.7 mM, Hill coefficient n = 1.5, and alpha (synergism with caffeine) = 0.2. For beta-D-glucose, Ki = 7.4 mM, n = 1.5, and alpha = 0.4. More than 20 glucose analogues have been synthesized and tested in kinetic experiments. Most were less effective inhibitors than glucose itself and the best inhibitor was alpha-hydroxymethyl-1-deoxy-D-glucose (Ki = 1.5 mM, n = 1.3, alpha = 0.4). The binding of 14 glucose analogues to glycogen phosphorylase b in the crystal has been studied at 2.4-A resolution and the structure have been refined to crystallographic R values of less than 0.20. The kinetic and crystallographic studies have been combined to provide rationalizations for the apparent affinities of glucose and the analogues. The results show the discrimination against beta-D-glucose in favor of alpha-D-glucose is achieved by an additional hydrogen bond made in the alpha-glucose complex through water to a protein group and an unfavorable environment for a polar group in the beta pocket. The compound alpha-hydroxymethyl-1-deoxy-D-glucose has an affinity similar to that of glucose and makes a direct hydrogen bond to a protein group. Comparison of analogues with substituent atoms that have flexible geometry (e.g., 1-hydroxyethyl beta-D-glucoside) with those whose substituent atoms are more rigid (e.g., beta-azidomethyl-1-deoxyglucose or beta-cyanomethyl-1-deoxyglucose) indicates that although all three compounds make similar polar interactions with the enzyme, those with more rigid substituent groups are better inhibitors. In another example, alpha-azidomethyl-1-deoxyglucose was a poor inhibitor. In the crystal structure the compound made several favorable interactions with the enzyme but bound in an unfavorable conformation, thus providing an explanation for its poor inhibition. Attempts to utilize a contact to a buried aspartate group were partially successful for a number of compounds (beta-aminoethyl, beta-mesylate, and beta-azidomethyl analogues). The beta pocket was shown to bind gentiobiose (6-O-beta-D-glucopyranosyl-D-glucose), indicating scope for binding of larger side groups for future studies.
115 citations
TL;DR: Vitamin B1, B2 and B6 deficiencies should be considered as another possible precipitating factor in recurrent aphthous ulceration.
Abstract: An evaluation of the thiamine, riboflavin and pyridoxine (vitamin B1, B2 and B6) status of 60 patients with recurrent mouth ulcers was performed Seventeen patients (282%) were found to be deficient in one or more of these vitamins Replacement therapy of these vitamins was given to a study group of deficient patients and a non-deficient group for one month At the end of therapy and after a follow-up period of 3 months, only those patients who had a B complex deficiency had a significant sustained clinical improvement in their mouth ulcers Vitamin B1, B2 and B6 deficiencies should, therefore, be considered as another possible precipitating factor in recurrent aphthous ulceration
105 citations
TL;DR: The hypothesis that poorer status in certain B vitamins is present in major depression, but blood measures may not reflect central nervous system vitamin function or severity of affective syndromes as measured by the assays and scales in the present study is supported.
Abstract: This study compared the B complex vitamin status at time of admission of 20 geriatric and 16 young adult non-alcoholic inpatients with major depression. Twenty-eight percent of all subjects were deficient in B2 (riboflavin), B6 (pyridoxine), and/or B12 (cobalamin), but none in B1 (thiamine) or folate. The geriatric sample had significantly higher serum folate levels. Psychotic depressives had lower B12 than did non-psychotic depressives. Poorer blood vitamin status was not associated with higher scores on the Hamilton Depression Rating Scale or lower scores on the Mini-Mental State Examination in either age group. The data support the hypothesis that poorer status in certain B vitamins is present in major depression, but blood measures may not reflect central nervous system vitamin function or severity of affective syndromes as measured by the assays and scales in the present study.
81 citations
TL;DR: Vitamin B-6 requirements of elderly men and women over 60 y old were studied and were not decreased in two of three subjects who ingested 54 g of protein daily.
Abstract: The vitamin B-6 requirements of 12 men and women over 60 y old were studied. The protocol consisted of a 5-d baseline period and four experimental periods during which the subjects successively received 0.003, 0.015, 0.0225 and 0.03375 mg of vitamin B-6/(kg body wt.d). Dietary protein was 1.2 or 0.8 g/(kg body wt.d). At 5- or 6-d intervals, xanthurenic acid (XA) after a 5-g L-tryptophan load and 4-pyridoxic acid (4-PA) in 24-h urine, erythrocyte aspartate aminotransferase activity coefficient (EAST-AC) and plasma pyridoxal-5'-phosphate (PLP) were measured. These measurements were abnormal during vitamin B-6 depletion but returned to normal during repletion. Men who ingested approximately 120 g protein/d required 1.96 +/- 0.11 mg of vitamin B-6 to normalize XA; women who ingested 78 g protein/d required 1.90 +/- 0.18 mg of vitamin B-6 to normalize XA. To attain normal levels of EAST-AC and 4-PA in men, 2.88 +/- 0.17 mg of vitamin B-6 were needed; to normalize PLP, 1.96 +/- 0.11 mg of vitamin B-6 were required. Women required 1.90 +/- 0.18 mg or more of vitamin B-6 to normalize these measurements. Vitamin B-6 requirements were not decreased in two of three subjects who ingested 54 g of protein daily. Thus, vitamin B-6 requirements of elderly men and women are about 1.96 and 1.90 mg/d, respectively.
67 citations
TL;DR: The studies indicate that the bioavailability of dietary PN-glucoside, although incomplete, is substantially greater in humans than previously found in rats, and the difference between oral and intravenous routes suggests a role of beta- glucosidase(s) of the intestinal mucosa, microflora, or both in the release of free PN from dietary PNs.
Abstract: Stable-isotopic methods were employed to evaluate the utilization of dietary pyridoxine-5'-beta-D-glucoside (PN-glucoside), a major form of vitamin B-6 in plant-derived foods, as a source of available vitamin B-6 for adult men (20-35 y old, n = 5). Deuterium-labeled forms of free pyridoxine (PN) and PN-glucoside were compared using the urinary excretion of labeled forms of the vitamin B-6 metabolite 4-pyridoxic acid as the main index of absorption and metabolism. When comparing orally administered, isotopically labeled PN and PN-glucoside in separate groups of subjects, similar bioavailability was observed although within-group variability was high. A dual-label study designed to examine the bioavailability of these compounds when administered simultaneously indicated that the utilization of deuterated PN-glucoside was 58 +/- 13% (mean +/- SEM) relative to that of deuterated PN. PN-glucoside was detected in all urine samples, which provided additional evidence of incomplete metabolic utilization. In contrast, intravenously administered PN-glucoside underwent approximately half the metabolic utilization of oral PN-glucoside. These studies indicate that the bioavailability of dietary PN-glucoside, although incomplete, is substantially greater in humans than previously found in rats. In addition, the difference between oral and intravenous routes suggests a role of beta-glucosidase(s) of the intestinal mucosa, microflora, or both in the release of free PN from dietary PN-glucoside.
63 citations
TL;DR: Results indicate that triglyceride-rich lipoproteins consist of several apoB-containing lipoprineins, including the LP-A-II:B complex, and that lipoprotein particles of similar size and density but distinct apolipoprotein composition also possess distinct metabolic properties.
61 citations
TL;DR: Apoproteins of spinach and pea light-harvesting chlorophyll a/b complexes associated with photosystem I were identified by their chlorophylla fluorescence spectra and protein sequences.
Abstract: Apoproteins of spinach and pea light-harvesting chlorophyll a/b complexes associated with photosystem I were identified by their chlorophyll fluorescence spectra and protein sequences
TL;DR: Diurnal fluctuations in the content and some structural and functional properties of the light-harvesting chlorophyll a/b pigment-protein complex of photosystem II (LHCII) in young developing wheat leaves grown under 16 hours light/8 hours dark illumination regime suggest a physiological role of diurnal rhythm of mRNA for LHCII for young developing leaves.
Abstract: Diurnal fluctuations were observed in the content and some structural and functional properties of the light-harvesting chlorophyll (Chl) a/b pigment-protein complex of photosystem II (LHCII) in young developing wheat (Triticum aestivum) leaves grown under 16 hours light/8 hours dark illumination regime. The fluctuations could be correlated with the diurnal oscillation in the level of mRNA for LHCII. The most pronounced changes occurred in the basal segments of the leaves. They were weaker or hardly discernible in the middle and tip segments. As judged from the diurnal variations of the Chl-a/Chl-b molar ratio, the LHCII content of the thylakoid membranes peaked around 2 pm. This can be accounted for by the cumulative effect of the elevated level of mRNA in the morning and early afternoon. In the basal segment, the extent of the fluctuation in the LHCII content was approximately 25%, as determined from gel electrophoresis (“green gels”). The amplitude of the principal bands of the circular dichroism (CD) spectra of isolated chloroplasts paralleled the changes in the LHCII content. Our circular dichroism data suggest that the newly synthesized LHCII complexes are incorporated into the existing helically organized macrodomains of the pigment-protein complexes or themselves form such macrodomains in the thylakoid membranes. Chl-a fluorescence induction kinetics also showed diurnal variations especially in the basal segments of the leaves. This most likely indicates fluctuations in the ability of membranes to undergo “state transitions.” These observations suggest a physiological role of diurnal rhythm of mRNA for LHCII in young developing leaves.
TL;DR: Sequence analysis of tryptic peptides from the Type II (28 kDa) CP29 polypeptide showed that it is also a member of the CAB family and is very similar or identical to the CP29Polypeptides previously isolated from spinach.
Abstract: CP29, the core chlorophyll a/b (CAB) antenna complex of Photosystem II (PSII), has two nuclearencoded polypeptides of approximately 26 and 28 kDa in tomato (Lycopersicon esculentum). Cab9, the gene for the Type 1 (26 kDa) CP29 polypeptide was cloned by immunoscreening a tomato leaf cDNA library. Its identity was confirmed by sequencing tryptic peptides from the mature protein. Cab9 is a single-copy gene with five introns, the highest number found in a CAB protein. In vitro transcription-translation gave a 31 kDa precursor which was cleaved to about 26 kDa after import into isolated tomato chloroplasts. The Cab9 polypeptide has the two highly conserved regions common to all CAB polypeptides, which define the members of this extended gene family. Outside of the conserved regions, it is only slightly more closely related to other PSII CABs than to PSI CABs. Sequence analysis of tryptic peptides from the Type II (28 kDa) CP29 polypeptide showed that it is also a member of the CAB family and is very similar or identical to the CP29 polypeptide previously isolated from spinach. All members of the CAB family have absolutely conserved His, Gln and Asn residues which could ligate the Mg atoms of the chlorophylls, and a number of conserved Asp, Glu, Lys and Arg residues which could form H-bonds to the polar groups on the porphyrin rings. The two conserved regions comprise the first and third predicted trans-membrane helices and the stroma-exposed segments preceding them.
TL;DR: In this paper, chemical analyses of the skim milk and retentates were done to determine the change in chemical composition that occurred during UF, and the results indicated that the loss of lactose and other soluble small molecular weight components.
TL;DR: A review of the literature suggests that the renal patient is most at risk for deficiency of folic acid, pyridoxine (B 6 ), and ascorbic acid (C), and daily replacement with the US Recommended Daily Allowance is suggested.
Journal Article•
TL;DR: This case illustrates an eruption resembling acne rosacea that was temporally associated with daily ingestion of high-dose B vitamin supplement that failed to respond to the usual treatment regimens for rosace, but promptly improved when use of the vitamin supplement was discontinued.
Abstract: Medications and other exogenous factors are known to be capable of exacerbating acne or precipitating acneiform eruptions. This case illustrates an eruption resembling acne rosacea that was temporally associated with daily ingestion of high-dose B vitamin supplement. The eruption failed to respond to the usual treatment regimens for rosacea, but promptly improved when use of the vitamin supplement was discontinued.
Book•
01 Mar 1991
TL;DR: In this paper, the authors present a proof for the existence of complex numbers in MATLAB for linear algebra using the concept of multiplicative multiplicative complex numbers (MCCN).
Abstract: 1 - Linear Equations And Matrices 2 - Solving Linear Systems 3 - Determinants 4 - Real Vector Spaces 5 - Inner Product Spaces 6 - Linear Transformations and Matrices 7 - Eigenvalues and Eigenvectors 8 - Applications of Eigenvalues and Eigenvectors (Optional) 9 - MATLAB for Linear Algebra 10 - MATLAB Exercises A P P E N D I X A Preliminaries A P P E N D I X B Complex Numbers A P P E N D I X C Introduction to Proofs
TL;DR: The present work indicated the possibility of a direct association between the genetic characteristics represented in the B complex and humoral antibody response in a broiler population.
TL;DR: It is suggested that light permits translation of polyprotein LHCP II precursors on cytoplasmic ribosomes of the rough endoplasmic reticulum (ER) and that these pass through the ER to the Golgi where, presumably, further modifications take place.
Abstract: Like other green photosynthetic eukaryotes, cells of Euglena gracilis var. bacillaris and strain Z contain a light-harvesting chlorophyll a/b complex associated with photosystem II. In Euglena , the formation of the 26.5 kDa principal light-harvesting chlorophyll a/b binding protein of photosystem II (LHCP II) has a number of unusual features. The precursors to LHCP II are large polyproteins containing multiple copies of LHCP II, and photocontrol of their formation is largely translational. Under conditions favoring LHCP II accumulation in the thylakoids, a reaction with anti-LHCP II antibody can be observed in the Golgi by immunogold electron microscopy. The timing of the immunoreaction in the Golgi in synchronous cells and in cells undergoing normal light-induced chloroplast development suggests that the nascent LHCP II passes through the Golgi on the way to the thylakoids. The compartmentalized osmiophilic structure (COS) also shows an immunoreaction. These observations, and others discussed in this paper, suggest that light permits translation of polyprotein LHCP II precursors on cytoplasmic ribosomes of the rough endoplasmic reticulum (ER) and that these pass through the ER to the Golgi where, presumably, further modifications take place. Since an LHCP II immunoreaction is found in Golgi vesicles, these may transport the nascent LHCP II to the plastid and facilitate its uptake.
Journal Article•
TL;DR: Concurrent administration of vitamins B-Complex or ascorbic acid, along with organophosphorous pesticide Malathion or carbamate pesticide Rogor could significantly decrease the chromosome-clastogeny rate induced by the pesticides alone in the metaphase chromosomes of bonemarrow cells.
Abstract: Concurrent administration for one week of vitamins B-Complex (0.3 ml of 1% Polybion) or ascorbic acid (0.25 ml of 1% Redoxon, to 8-week old albino swiss mice, Mus musculus along with organophosphorous pesticide Malathion or carbamate pesticide Rogor (both 1 microliters/kg b.wt.) could significantly decrease the chromosome-clastogeny rate induced by the pesticides alone in the metaphase chromosomes of bonemarrow cells. The vitamins were not clastogenic, whereas the Malathion proved to be clastogenic four-times and Rogor six-times more than the control rate. The vitamins seem to reduce the incidence of fragmentation and subsequent rearrangements induced by the pesticides. On the basis of the available literature, it is presumed that the vitamins might be preventing the formation of mutagenic lipid conjugates of biometabolised forms of the pesticides.
TL;DR: It is indicated that oral calcitriol has an inhibitory effect on iPTH secretion in the hours immediately after oral phosphate administration in children with vitamin D-resistant rickets.
TL;DR: Administration of vitamin C, either concurrently or as pre- and post-treatment to the pesticide exposure, was very much helpful in minimising mitoinhibition and clastogeny induced by two organophosphorus pesticides, Malathion and Rogor.
Abstract: Administration of vitamin C, either concurrently or as pre-and post-treatment to the pesticide exposure, was very much helpful in minimising mitoinhibition and clastogeny induced by two organophosphorus pesticides, Malathion and Rogor. The concurrent treatment with vitamin C was more effective than the two other modes of its supplementation.
TL;DR: The higher urinary 4-PA excretion in older rats may reflect a lower vitamin B-6 requirement; however, the lower PLP content of gastrocnemius muscle may indicate an age-related decrease in vitamin B -6 body stores.
Abstract: Vitamin B-6 vitamer distribution and activities of vitamin B-6 metabolizing enzymes were evaluated in aging male and female Wistar rats fed a purified diet (containing 250 g of casein and 6 mg of pyridoxine hydrochloride per kg) from weaning until 31 mo of age. Plasma pyridoxal 5'-phosphate (PLP) concentration became lower with increasing age, with the largest decrease in the 1st yr of life. An age-related change in vitamin B-6 distribution between the various tissues examined was observed: B-6 vitamer content increased in heart and brain, whereas PLP content decreased in gastrocnemius muscle, kidney and liver. The decrease in muscle PLP content occurred in concert with a decrease in muscle glycogen phosphorylase activity. Urinary 4-pyridoxic acid (4-PA) excretion increased with age, especially in female rats, in parallel with an increase in liver pyridoxal oxidase and pyridoxal dehydrogenase activities. Age-related changes in vitamin B-6 distribution were probably not causally related to changes in activity of vitamin B-6 metabolizing enzymes; they were regarded as consequences of changes in protein metabolism. The higher urinary 4-PA excretion in older rats may reflect a lower vitamin B-6 requirement; however, the lower PLP content of gastrocnemius muscle may indicate an age-related decrease in vitamin B-6 body stores.
TL;DR: Vitamin B-6 deficient diet fed rat showed increased lipid peroxidation reactions in liver when compared to that of control as discussed by the authors, which may have been an indirect secondary effect of the general disruption of metabolism associated with vitamin B6 deficiency.
Abstract: Vitamin B-6 deficient diet fed rat showed increased lipid peroxidation reactions in liver when compared to that of control. Liver homogenate of vitamin B-6 deficient rats showed enhanced susceptibility to lipid peroxidation upon incubation with NADPH or ascorbate or t-butyl hydroperoxide. Vitamin B-6 deficient liver showed increased levels of lipids, oxalate, calcium, iron, and copper, and decreased levels of antioxidants, ascorbic acid, α-tocopherol, reduced glutathione, total thiol groups, and antioxidant enzymes, glutathione peroxidase, catalase, and glucose 6-phosphate dehydrogenase. Further, vitamin B-6 deficient liver showed enhanced level of hydroxyl radicals and hydroperoxides when compared to that of control liver. The decreased antioxidant protection against free radicals may have led to increased levels of hydroxyl radicals and hydroperoxides which in turn may have led to increased levels of diene conjugates, thiobarbutric acid reactive substances, and lipofuscin-like pigments in liver homogenate. These observations may be an indirect secondary effect of the general disruption of metabolism associated with vitamin B-6 deficiency.
TL;DR: The metabolic pathway involved (PLP synthesis and/or PLP degradation) was observed to depend on degree of vitamin B-6 deficiency and volume of distribution of PLP as well as of PL was larger than in controls.
Abstract: Biokinetic parameters of plasma pyridoxal-5'-phosphate (PLP) and pyridoxal (PL) disposition were studied in male Wistar rats (age 8 mo) fed a purified diet containing less than 0.5, approximately 3 or approximately 6 mg pyridoxine.HCl/kg diet from weaning, with animals fed the 6 mg/kg diet serving as the control group. Basal plasma PLP concentration was lower in both the less than 0.5 and 3 mg/kg diet groups than in control animals (98 +/- 12, 314 +/- 40 and 514 +/- 56 nmol/L, respectively). Basal plasma PL concentration was lower in the less than 0.5 mg/kg diet group only [60 nmol/L (measured in pooled samples), 190 +/- 73 and 235 +/- 63 nmol/L for less than 0.5, 3 and 6 mg/kg diet groups, respectively]. In both the less than 0.5 and 3 mg/kg diet groups, PLP clearance was lower than in control rats (0.158 +/- 0.025, 0.131 +/- 0.040 and 0.240 +/- 0.051 L.h-1.kg body weight-1, respectively). In the less than 0.5 mg/kg diet group, PLP synthesis was more efficient than in control animals (34.7 +/- 9.3, 12.1 +/- 2.5 and 16.7 +/- 11.4% for less than 0.5, 3 and 6 mg/kg diet groups, respectively). In both the less than 0.5 and 3 mg/kg diet groups, volume of distribution of PLP as well as of PL was larger than in controls. It is concluded that B-6 vitamer metabolism is influenced by vitamin B-6 status. The metabolic pathway involved (PLP synthesis and/or PLP degradation) was observed to depend on degree of vitamin B-6 deficiency.
TL;DR: The distribution pattern over liver and kidneys indicates that at least part of the cobalamins, measured by a specific radioassay, may actually be analogues, and illustrate that cobalamin from algae are indeed absorbed by the rat.
Abstract: The availability of vitamin B-12 from two different seafood products, nori ( Porphyra tenera ) and spirulina ( Spirulina sp.), was evaluated in rats. Male weanling Wistar rats ( n = 30) were fed a vitamin B-12 deficient diet for six weeks, followed by a four-week repletion period in which the rats were supplemented with equal doses of vitamin B-12, either supplied as pure cyanocobalamin, or as dried spirulina or nori. No difference in body weight gain, relative liver, or relative kidney weight could be demonstrated between the groups in either the depletion or repletion period. Low serum, liver, and kidney cobalamin contents were measured after the depletion period using an Intrinsic Factor-based radioassay. However, no hematological abnormalities could be demonstrated in the B-12 depleted rats. After repletion, cobalamin contents of serum and kidney were significantly lower, and liver cobalamin content was higher, for both the nori- and spirulina-fed rats than for the cyanocobalamin-supplemented controls. These data illustrate that cobalamins from algae are indeed absorbed by the rat. However, the distribution pattern over liver and kidneys indicates that at least part of the cobalamins, measured by a specific radioassay, may actually be analogues.
TL;DR: The first serum-free, partly defined medium for cultivating the human enteric pathogen, Entamoeba histolytica, and the reptilian amebae E. barreti, E. invadens, and E. terrapinae is described.
Abstract: We describe the first serum-free, partly defined medium (PDM-805) for cultivating the human enteric pathogen, Entamoeba histolytica, and the reptilian amebae E. barreti, E. invadens, and E. terrapinae. PDM-805 was developed by the stepwise replacement of yeast extract, bovine serum, and a casein peptone digest in TYI-S-33, a medium widely used for the axenic cultivation of these parasites. The defined components include amino acids, carbohydrates, B vitamins, ascorbic acid, tocopherol, thioctic acid, nucleic acid precursors, trace metals, and phosphate buffers. The undefined components include a highly purified bovine serum albumin, a lipoprotein-cholesterol solution from bovine serum, and a dialyzable, autoclavable, water-soluble growth factor(s) having a molecular weight of less than 3,500 prepared from casein peptone. To date, studies on the growth requirements of E. histolytica, strain 200:NIH, show the following are essential for sustained multiplication of this ameba: iron, glucose, biotin, folic acid, niacinamide, pantothenate, pyridoxal, riboflavin, thiamine, cysteine, an ammonium moiety (in addition to that present in cysteine), bovine serum albumin, lipoprotein-cholesterol, and casein peptone dialysate.
TL;DR: In liver, the vitamin deficiency specifically elevated the specific activities of the mitochondrial NADH-linked and microsomal NADPH-linked enzymes, likely the isozymes involved in vitamin B-12 coenzyme synthesis.
Abstract: Rat liver contains both NADH- and NADPH-linked aquacobalamin reductases, which are involved in the synthesis of the vitamin B-12 coenzymes and are distributed in both the mitochondrial and microsomal membranes. To clarify the physiological roles of these hepatic enzymes, vitamin B-12-deficient rats were used to study the effect of the deficiency on the enzyme activities. Male rats fed a vitamin B-12-deficient diet for 11 wk developed a severe vitamin B-12 deficiency with a high urinary methylmalonate excretion (214.3 +/- 115.2 mumol/d) and approximately 96% lower hepatic vitamin B-12 content. Tissues of the vitamin B-12-deficient rats were assayed for NADH- and NADPH-linked aquacobalamin reductase activities. The specific activities of both enzymes in homogenates of liver, kidney or upper intestine were shown to be three- to 20-fold greater in the vitamin-deficient rats than in the control rats. In liver, the vitamin deficiency specifically elevated the specific activities of the mitochondrial NADH-linked and microsomal NADPH-linked enzymes. These are likely the isozymes involved in vitamin B-12 coenzyme synthesis.
TL;DR: Based on movement in 6 TLC solvents, elution in HPLC, and ultraviolet and infrared spectra, two of these metabolites have been identified as 5-pyridoxic acid and its lactone as mentioned in this paper.
Abstract: Plasma and urine from individuals ingesting large amounts of vitamin B 6 contain several unidentified vitamin B 6 metabolites. Based on movement in 6 TLC solvents, elution in HPLC, and ultraviolet and infrared spectra, two of these metabolites have been identified as 5-pyridoxic acid and its lactone. These two compounds can account for 10–20% of the urinary vitamin B 6 metabolites.
TL;DR: The purpose of this review is to present the information currently available pertaining to the relationship between vitamin B 6 and steroid hormone action, followed by a brief discussion of the role of the vitamin in growth and development, neural function, and immune surveillance.
Abstract: Vitamin B 6 is a water soluble vitamin necessary for normal growth, development, and biological function.~'2 The physiologically active form of the vitamin, synthesized from precursors obtained through the diet, is historically known for its role as a cofactor in many enzymatic reactions regulating amino acid metabolism 3 and nervous system function. 47 In addition, the vitamin is also involved in modulating lipid metabolism, gluconeogenesis, s and immune function. 9t° While these enzymatic reactions represent the bestcharacterized functions of vitamin B 6, m o r e recent evidence suggests a role for this vitamin in a nontraditional aspect of metabolism, steroid hormone action. This novel and provocative aspect of vitamin B6 function has been suggested through indirect results obtained in several laboratories ~1 and elucidated through more direct molecular studies of the glucocorticoid hormone receptor. ~2 The purpose of this review is to present the information currently available pertaining to the relationship between vitamin B 6 and steroid hormone action. We will begin with a synopsis of the synthesis and distribution of vitamin B 6 throughout the body, followed by a brief discussion of the role of the vitamin in growth and development, neural function, and immune surveillance. We will then concentrate on the role for vitamin B 6 in steroid hormone action, ending with a speculative discussion on the future directions and significance of research in this area.