Showing papers on "B vitamins published in 1989"

Mycetocyte symbiosis in insects.

Abstract: 1. Non-pathogenic microorganisms, known as mycetocyte symbionts, are located in specialized 'mycetocyte' cells of many insects that feed on nutritionally unbalanced or poor diets. The insects include cockroaches, Cimicidae and Lygaeidae (Heteroptera), the Homoptera, Anoplura, the Diptera Pupiparia, some formicine ants and many beetles. 2. Most mycetocyte symbionts are prokaryotes and a great diversity of forms has been described. None has been cultured in vitro and their taxonomic position is obscure. Yeasts have been reported in Cerambycidae and Anobiidae (Coleoptera) and a few planthoppers. They are culturable and those in anobiids have been assigned to the genus Torulopsis. 3. The mycetocyte cells may be associated with the gut, lie free in the abdominal haemocoel or be embedded in the fat body of the insect. The mycetocytes are large polyploid cells which rarely divide and the symbionts are restricted to their cytoplasm. 4. The mycetocyte symbionts are transmitted maternally from one insect generation to the next. In many beetles (Anobiidae, Cerambycidae, Chrysomelidae and cleonine Curculionidae), the microoganisms are smeared onto the eggs and consumed by the hatching larvae. In other insects, they are transferred from mycetocytes to oocytes in the ovary, a process known as transovarial transmission. The details of transmission in the different insect groups vary with the age of the mother (adult, larva or embryo) at which symbiont transfer to the ovary is initiated; whether isolated symbionts or intact mycetocytes are transferred; and the site of entry of symbionts to the egg (anterior, posterior or apolar). 5. Within an individual insect, the biomass of symbionts varies in a regular fashion with age, weight and sex of the insect. Suppression of symbiont growth rate and lysis of 'excess' microorganisms may contribute to the regulation of symbionts (including freshly-isolated preparations of unculturable forms) are used to investigate interactions between the partners. However, some methods to obtain aposymbiotic insects (e.g. antibiotics and lysozyme) deleteriously affect certain insects and aposymbionts may differ from the symbiont-containing stocks from which they were derived. 7. The mycetocyte symbionts have been proposed to synthesize various nutrients required by the insect. The symbionts of beetles and haematophagous insects may provide B vitamins and those in cockroaches and the Homoptera essential amino acids. The role of symbionts in the sterol nutrition of insects is equivocal. 8. Mycetocyte symbionts may have evolved from gut symbionts or guest microorganisms. The association is monophyletic in cockroaches but polyphyletic in many groups, including the sucking lice, beetles and scale insects.(ABSTRACT TRUNCATED AT 400 WORDS)

Two interconnected B vitamins: riboflavin and pyridoxine

Abstract: Ce rapport analyse et discute les nombreuses investigations qui ont ete realisees dans le but d'elucider le role des vitamines B 2 et B r , examiner leur metabolisme et caracteriser les effets pathologiques causes par leur carence

Electric Circuit Analysis

Abstract: 1 Introduction. 2 Resistive Circuits. 3 Dependent Sources and Op Amps. 4 Analysis Methods. 5 Energy Storage Elements. 6 First Order Circuits. 7 Second Order Circuits. 8 Sinusoidal Sources and Phasors. 9 AC Steady State Analysis. 10 AC Steady State Power. 11 Three Phase Circuits. 12 The Laplace Transform. 13 Circuit Analysis in the S Domain. 14 Frequency Response. 15 Transformers. 16 Two-port Circuits. 17 Fourier Series and Transform. 18 Putting it all Together: Linear Circuit Design. Appendices. A Matrix Methods. B Complex Numbers and the Complex Exponential. C Circuit Topology. D SPICE Reference Guide. E MATLAB Reference Guide. F Answers to Selected Odd-Numbered Problems.

Growth promoting substances of Cyanobacteria. I: Vitamins and their influence on rice plant

Abstract: The beneficial effects of algal inoculation in the presence of N-fertilizers has been most frequently interpreted as an action of biologically potent substances produced by cyanobacteria. The present investigation deals with the analysis on vitamins in two nitrogen-fixing cyanobacterial species

Effect of gamma irradiation on the B vitamins of pork chops and chicken breasts.

Abstract: A study was made of the effect of low-dose gamma irradiation on the content of thiamine (B1), riboflavin (B2), niacin, pyridoxine (B6) and cobalamin (B12) in pork chops, and thiamine, riboflavin and niacin in chicken breasts. Gamma irradiation from a caesium-137 source was used to irradiate the samples in a range of 0.49 to 6.65 kGy from -20 to +20 degrees C. Over the range of dose and temperature studied it was possible to derive a mathematical expression for predicting the losses. A calculation was made of the effect of the loss of thiamine, riboflavin and niacin due to irradiation on the overall loss of these vitamins in the American diet. The losses of riboflavin and niacin were of the order of a fraction of a per cent. Pork is an important source of thiamine, but the calculated loss at 1.0 kGy of this vitamin in cooked pork was only 1.5 per cent. There were initial increases with radiation doses up to 2-4 kGy in the measured concentrations of riboflavin and niacin in both pork and chicken. The increases were highly significant, and are of concern both to the study of radiation effects and the chemical method of the determination of these two vitamins.

Do Dietary Levels of Pantothenic Acid Regulate Its Intestinal Uptake in Mice

Abstract: While regulation of intestinal transporters is established for other nutrients, evidence concerning regulation of intestinal vitamin transport is scanty. Hence, we compared intestinal pantothenic acid (PA) uptake in mice fed diets with high, normal and deficient PA levels. PA uptake is distributed along the small intestine, Na(+)-dependent and saturable. Signs of PA deficiency were weight loss or reduced growth, then hair loss and exudation around the eyes, then diarrhea and hindleg paralysis and splenomegaly, and finally death. Treatment of mice with an antibiotic was found to be necessary to elicit severe signs of PA deficiency, probably because mice normally can obtain PA synthesized by intestinal bacteria. Dietary PA levels had no effect on intestinal PA uptake at 5 microM. A small increase in the Vmax of uptake, observed in late-stage deficiency, is probably too small to be physiologically significant. Comparison with published results for other water-soluble vitamins suggests that intestinal transporters may be regulated only for vitamins absorbed predominantly by carrier-mediated transport and subject to natural deficiency states.

Vitamin B-6 requirement of growing kittens.

Abstract: Two experiments were conducted to determine the vitamin B-6 requirement for growing kittens. Ten kittens were divided into two groups and given a purified diet containing 8.0 mg pyridoxine (PN)/kg diet (+PN) or a PN-free diet (-PN) for 11 wk. Daily body weight gain, food intake, weekly plasma free amino acids, plasma B-6 vitamers, urinary oxalate excretion, hemoglobin (Hb) and hematocrit were measured. Kittens fed a -PN diet had depressed body weight gain, food intake, plasma pyridoxal phosphate (PLP) and pyridoxal (PL), Hb and hematocrit, and had elevated urinary oxalate, plasma tyrosine and plasma cystathionine. In a second experiment, 24 kittens were given a -PN diet for 45 d to deplete their body reserves. The kittens were then divided into six groups of four kittens each and given a purified diet containing either 0.5, 1.0, 2.0, 3.0, 4.0 or 8.0 mg PN/kg diet for 46 d. Following supplementation, positive responses in body weight gain, PLP, Hb and hematocrit, and decreased urinary oxalate excretion, plasma tyrosine and plasma cystathionine occurred in all groups except those fed 0.5 mg PN/kg diet. At the end of the repletion period, kittens fed 1.0 mg PN/kg diet had lower body weight gain, higher plasma tyrosine and cystathionine, slower rate of decrease in urinary oxalate, and lower values for Hb, hematocrit and PLP than did the kittens from groups fed 2.0-8.0 mg PN/kg diet. These findings indicate that the dietary requirement for PN is greater than 1.0 mg/kg diet, but 2.0 mg PN/kg diet is adequate for growing kittens given a 35% casein diet.

Improvement of fine motoric movement control by elevated dosages of vitamin B1, B6, and B12 in target shooting.

Abstract: Oral application of elevated dosages of vitamin B1, B6 and B12 have been found to improve target shooting in marksmen, recruited from a local pentathlon association, in two different studies. Study 1 was performed in an open controlled design, whereas in study 2 the group treated with B-vitamins was compared in a double-blind fashion with a placebo control group including 8 by 8 volunteers and 10 by 9 volunteers, respectively. The volunteers were randomly assigned to the groups. Performance quality was followed in both studies over a period of 8 weeks, while participants were continuously supplied with a combination of vitamins B1, B6 and B12 (Neurobion or Neurobion forte; E. Merck, Darmstadt, and Cascan, Wiesbaden, Germany). In both studies, marksmen in the vitamin-treated groups showed statistically significant, considerably improved firing accuracy as measured by the number of points achieved within a series of 20 shots at each examination. In study 2 the degree of improvement was linearly dependent on the duration of vitamin treatment, whereas the placebo-treated group, similar to the untreated control group in study 1, did not show any prominent change. Performance quality in marksmenship closely correlates with the magnitude of physiological tremor. Tremor can also be involved in the regulation quality of sensory-motor control systems. Thus, an improvement in firing accuracy as found in both studies is by the same token an improvement of fine motor control of slow movements, involving, for example, basal ganglia.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of vitamin B-6 nutrition on the levels of dopamine, dopamine metabolites, dopa decarboxylase activity, tyrosine, and GABA in the developing rat corpus striatum.

Abstract: Evidence presented in this manuscript indicates that prenatal and postnatal vitamin B-6 undernutrition produces the loss of dopamine (DA) in the corpus striatum of the developing rat brain. The concentration of striatal DA in rats fed vitamin B-6 inadequate diets was significantly lower than rats fed optimal diets at 28 and 56 days of age. The differences in striatal DA concentrations among vitamin B-6 dietary groups was more evident with age. Measurements of the major metabolites of DA, homovanillic acid (HVA), and 3,4-dihydroxyphenylacetic acid (DOPAC) in rat corpus striatum showed a significant decrease in HVA level in B-6 restricted rats compared to B-6 sufficient groups. Striatal DOPAC levels were not significantly different among any of the groups at any age. The activity of dopa decarboxylase holoenzyme was found to be significantly lower in the corpus striatum of rats fed suboptimal B-6 diets. Whether this finding has a significant effect on DA levels has yet to be determined since dopa decarboxylase is not the rate-limiting enzyme in the synthesis of DA. In an effort to determine the underlying mechanism for the loss of striatal DA, the concentration of its precursor tyrosine (TYR) was measured. Vitamin B-6 undernutrition had no significant effect on the levels of TYR in rat corpus striatum. The concentration of the inhibitory neurotransmitter GABA was also measured. The results indicate that as expected the levels of striatal GABA were significantly lower than controls at 14 and 28 days of age. On the other hand, striatal GABA levels in B-6 restricted rats did not differ from controls at 56 days of age.(ABSTRACT TRUNCATED AT 250 WORDS)

Monitoring of B-complex vitamins in yogurt during fermentation

Abstract: Eight commercially available yogurt starter cultures were examined for their ability to synthesize water-soluble vitamins. In order to yield comparable assaying conditions, 12·5% reconstituted whole milk was used for yogurt production throughout the experiments. When applying the traditional method of yogurt manufacture (short-time incubating at 42 °C/3–4 h) with all cultures the following vitamins were enriched during fermentation by more than 20%: thiamin (two cultures), pyridoxine (four cultures), folic acid (one culture), and biotin (two cultures). Two starter cultures were selected and used to compare vitamin profiles during the two different methods of fermentation. In contrast to short-time incubation, long-time yogurt production (30 °C/14–16 h) led to a lesser production of folic acid, but to increased concentrations of thiamin and of nicotinic acid.

Response of B-6 vitamers in plasma, erythrocytes and tissues to vitamin B-6 depletion and repletion in the rat.

Abstract: We determined the response patterns of B- 6 vitamers in blood and tissues to vitamin B-6 depletion and repletion. B-6 vitamers were measured in plasma, erythrocytes, liver, muscle, kidney, heart, brain, spleen and lung by reverse-phase high performance liquid chromatog- raphy in male rats pair-fed control or vitamin B-6-deflcient diets for 2 or 4 wk, or for 4 wk followed by 1 wk of repletion with the control diet (n = 4/group). Food intake (15.6 ± 0.3 g/d, mean ±SEM;n = 28) and body weight (190 ± 2 and 290 ±5 g at wk 0 and 5, respectively; n = 28) of control groups were not different from those of deficient groups throughout the study. After 2 wk of vitamin B-6 depletion, tissue concentrations of pyridoxal phosphate (PLP) and pyridoxamine phosphate (PMP) were about 50% and 10â€"40% lower, respectively, in the deficient than in the control group (except for spleen PMP); in plasma and erythrocytes, PLP and pyridoxal concentrations were about 90% lower in the deficient group. Differences in vitamer concentrations between control and deficient groups were not larger after 4 wk of depletion than after 2 wk. Vitamer concentrations in plasma, erythrocytes and all tissues re turned to control levels after 1 wk of repletion with the control diet. These results demonstrate that B-6 vitamers in blood and tissues of the rat respond quickly and re- versibly to changes in dietary vitamin B-6, with larger per centage changes occurring in plasma and erythrocytes than in tissues. J. Nutr. 119: 1940-1948, 1989.

Brain glutamate and γ-aminobutyrate (GABA) metabolism in thiamin-deficient rats

Abstract: The brain metabolism of glutamate and gamma-aminobutyrate (GABA) was investigated in thiamin-deficient and pair-fed control rats, in order to determine whether the GABA shunt may provide an important alternative to 2-oxo-glutarate dehydrogenase (EC 1.2.4.2) in energy-yielding metabolism in thiamin deficiency. Brains from thiamin-deficient animals contained less glutamate, 2-oxo-glutarate and GABA than those from control animals. The brain content of ATP was unaffected by thiamin deficiency. After intracerebroventricular injection of [14C]glutamate, the specific radioactivity of GABA in the brains from deficient animals was 45-50% higher than that in controls, suggesting a considerable increase in the metabolic flux through the GABA shunt in thiamin deficiency. Brain GABA showed a marked circumannual variation, with a peak in mid-summer and a minimum value in mid-winter.

Adequacy of vitamin supply under maximal sustained workloads: the Tour de France.

Abstract: In the Tour de France competing cyclists must pedal about 4000 km over a period of three weeks with only one day allowed for rest. The course includes 30 mountains, the highest of which reaches an altitude of approximately 2700 m. The energy expenditure values of these cyclists range from a mean of 25.4 MJ/day to peak values of 32.7 MJ/day. These are the highest values that have ever been reported for a period longer than seven days. On the basis of the food records of 5 cyclists, it turned out that 62 En.% is derived from CHO, 15 En.% from protein, and 23 En.% from fat. Since the food choice is primarily focused on digestibility and energy content, this results in a frequent consumption of sweet cakes and CHO-rich fluids. Some 49% of the energy is consumed in between meals. Such a nutritional pattern leads to a lowering of the nutrient density especially with respect to the B-vitamins. Intake of vitamins B1, B2, B6, and C, including contribution from enriched sport drinks, was 1.97 mg, 4.96 mg, 2.40 mg, and 158 mg, respectively. Besides this, intramuscular injections of megadosis vitamins of B1, B2, B6, nicotinamide, pantothenic acid, and especially B12 did increase the intake drastically. This was reflected in high blood concentrations of vitamins. Except for folic acid, vitamins (B1, B2, B6, and B12) exceeded the upper limits of the values from a reference group, particularly B12, which exceeded the reference values by up to 400%. During the Tour, vitamin concentrations remained essentially unchanged.

Effects of increased major histocompatibility complex dosage on chicken monocyte-macrophage function.

Abstract: The influence of major histocompatibility complex (B complex) dosage on monocyte-macrophage function was examined using 4- to 6-week-old trisomic strain chickens. Di- (B15B15), tri- (B15B15B15), and tetrasomic (B15B15B15B15) progeny were produced from trisomic x trisomic crosses. Although mononuclear leukocytes from tetrasomics exhibited enhanced chemotactic activity in response to both f-met-leu-phe and Enterobacter cloacae culture supernatant as compared with that of cells from other groups, the ability to generate peritoneal exudate cells in response to intraperitoneal Sephadex stimulation was similar in all groups. Among peritoneal exudate cells, tetrasomic birds produced a significantly lower percentage of adherent macrophages with a higher proportion of Fc receptor-positive and CMTD-2-reactive macrophages than either disomic or trisomic chickens. Both tetrasomic and trisomic peritoneal macrophages exhibited a reduced phagocytic activity for unopsonized but not opsonized SRBC than was found with disomic macrophages. Thus, the number of major histocompatibility complex copies present in cells appears to influence monocyte-macrophage function.

Effects of Vitamin B-6 Deficiency on Selenium Metabolism in the Rat

Abstract: Rats were fed for 23 d diets adequate or deficient in vitamin B-6 and containing selenium as either sodium selenite, selenocysteine (SeCys) or selenomethionine (SeMet). They were then injected with 75Se of the same chemical form and killed 2 d later. Tissue deposition of stable and radiotracer selenium and the activity of glutathione peroxidase (GSHPx) were used to assess selenium utilization. Erythrocyte levels of selenium and GSHPx were lower in vitamin B-6--deficient animals for all forms of selenium; however, 75Se deposition in erythrocytes was not affected by vitamin B-6 status. The activities of cystathionine lyase, aspartate aminotransferase and selenocysteine lyase were lower in livers of vitamin B-6--deficient rats than in vitamin B-6--supplemented rats. The proportion of liver and kidney 75Se soluble in 5% trichloroacetic acid and 0.1 M 2-mercaptoethanol was consistently lower in vitamin B-6--deficient animals, but cation-exchange chromatography of tissue extracts did not identify a specific low-molecular-weight species. Tissue retention of 75Se provided as SeMet was increased in vitamin B-6--deficient animals, but the proportion of 75Se retained in muscle and liver as SeCys was significantly reduced. These findings suggest that the conversion of SeMet to a form available for GSHPx synthesis is reduced by vitamin B-6 deficiency.

Effect of carnitine on propionate metabolism in the vitamin B-12--deficient rat.

Abstract: Acyl-CoA thioesters are generated during the oxidation of organic acids in mammalian systems. Vitamin B-12 deficiency is associated with decreased L-methylmalonyl-CoA mutase activity, and consequent accumulation of propionyl-CoA and methylmalonyl-CoA. The formation of propionylcarnitine from propionyl-CoA and carnitine provides an alternative pathway to remove propionyl-CoA from cells. Hepatocytes isolated from vitamin B-12--deficient rats metabolized propionate (1 mM) to CO2 and glucose at only 23% and 12%, respectively, of the rates observed in hepatocytes from control animals. In contrast, no difference was seen in rates of pyruvate metabolism by hepatocytes from control and vitamin B-12--deficient rats. Addition of carnitine (10 mM) to hepatocyte incubations increased the rate of propionylcarnitine formation 10- to 20-fold without altering conversion of propionate to CO2 or glucose. The rate of propionylcarnitine formation was not affected by vitamin B-12 deficiency. When carnitine (10 mM) was added, propionylcarnitine generation represented 65-71% of total propionate utilization in hepatocytes isolated from vitamin B-12--deficient rats. Gluconeogenesis from [1-14C]pyruvate was inhibited by 1 mM propionate in hepatocytes from vitamin B-12--deficient rats. No effect of 1 mM propionate on glucose formation from pyruvate was seen using hepatocytes from control rats. Intraperitoneal administration of L-carnitine resulted in a significant increase in urinary propionylcarnitine excretion from vitamin B-12--deficient rats, but not from control animals. The results demonstrate that exogenous carnitine can significantly enhance propionyl-group utilization via the formation of acylcarnitines under the conditions of impaired acyl-CoA metabolism associated with vitamin B-12 deficiency.

A study on the occurrence of coprophagy behavior and its relationship to b-vitamin status in growing-finishing pigs

Abstract: Forty-eight 5-wk-old piglets were grouped into six blocks of eight pigs each. Each block comprised two pens of four pigs, two castrates and two females; one pen had solid floor (free access to feces) while the other had slatted floor (limited access to feces). Pigs were fed ad libitum, for 18 wk, a diet computed to meet NRC requirements. At 10, 16 and 22 wk of age, a comparative evaluation of feces intake on each floor type was carried out through utilization of a marker, chromium oxide, in the diet. At the same ages, the behavioral variables — rooting the floor, rooting the walls, rubbing and biting penmates — were recorded during a period of 24 h to evaluate their relationship with weight gain, serum concentrations of folates and vitamin B12. The results showed that there was no effect (P > 0.09) of floor type on ingestion of feces. However, this last variable changed with age, a limited ingestion of feces occurring at 10 wk of age while there was no apparent excrement intake at 16 or 22 wk. Some of the...

Nutrition Research with Lactic Acid Bacteria: A Retrospective View

Abstract: From the above discussion, it is apparent that one or another of the lactic acid bacteria requires each of the B vitamins required by animals and that assay methods developed during study of nutrition of bacteria and yeasts have played a large role in the initial or independent discovery, isolation, and characterization of vitamins, vitamin derivatives, and functionally similar substances. Clear examples include biotin, biocytin, lipoic acid, nicotinic acid, pantothenic acid, pantetheine, folic acid and tetrahydrofolic acid (and their derivatives), pyridoxal, pyridoxamine, and pyridoxamine phosphate. Improved assay methods that use these organisms also have provided much of the currently available information concerning distribution and stability of the vitamins in natural products, while quantitative inconsistencies between assays, when traced to their origin, have frequently revealed previously unknown metabolic precursors, products, or functions of the vitamins and have provided explanations of the mechanisms by which certain peptide growth factors act. Extension of such studies to organisms that cannot yet be grown in media of known composition should provide additional insights into currently obscure areas of nutrition.

EFFECTS of GAMMA-IRRADIATION ON THE CONTENTS of THIAMIN, RIBOFLAVIN, AND VITAMIN B-12 IN DAIRY PRODUCTS FOR LOW MICROBIAL DIETS

Abstract: Frozen dairy products were exposed to 40 kGy (4 Mrad) of cobalt-60 irradiation to sterilize them for the low microbial diets of immunosuppressed patients. In this study, the levels of thiamin, riboflavin, and vitamin B-12 were measured in Cheddar cheese, mozzarella cheese, yogurt bars, ice cream, and nonfat dry milk before and after irradiation at −78°C. There was no significant change in the levels of thiamin, riboflavin, or vitamin B-12 after irradiation. Samples of nonfat dry milk irradiated at three different temperatures (22°, 0 to 5°, or −78°C) sustained no significant loss of thiamin compared to levels in the nonirradiated fresh product. However, in irradiated mozzarella cheese, more thiamin was retained in products irradiated at −78°C than at 0 to 5°C. Irradiation of cheese, yogurt, ice cream, and nonfat dry milk at −78°C appeared to preserve the content of these three B vitamins.

Effects of prevention of coprophagy on pregnant mice--is coprophagy beneficial on a balanced diet?

Abstract: The effects of prevention of coprophagy on reproductive performance were examined in ICR mice. Females were treated with restrainers in order to prevent them from ingesting their feces from day 1 through day 17 of pregnancy. The restrained animals fed a commercial diet did not show any clear adverse effects. In contrast, restrained dams fed a purified diet deficient in vitamin B12 exhibited stillbirths (14%) and abortions (7%). Restrained dams fed a diet lacking in vitamin B12 and folic acid also experienced frequent abortions (27%). In addition, six out of 14 restrained dams (43%) aborted when fed a vitamin B complex-deficient diet. Sham-restrained animals, fed the vitamin B complex deficient-diet, but able to ingest their feces trapped by smaller-mesh floors, escaped these adverse effects. Sham-restrained animals fed the commercial diet, however, showed only a slight improvement in their reproductive performance. In conclusion, coprophagy has nutritional significance as long as the diet is lacking at least B vitamins, especially vitamin B12 and folic acid, whereas it almost entirely loses its nutritional significance when the mouse has access to a balanced diet such as the one made available to the laboratory mice in the present study.