Stimulation of vitamin B12 formation in aerobically-grownRhodopseudomonas gelatinosa under microaerobic condition

1986 ◽  
Vol 8 (7) ◽  
pp. 491-496 ◽  
Author(s):  
N. Noparatnaraporn ◽  
K. Sasaki ◽  
Y. Nishizawa ◽  
S. Nagai
1984 ◽  
Vol 47 (5) ◽  
pp. 1067-1069 ◽  
Author(s):  
You-Hua Fa ◽  
J. Peter Kusel ◽  
Arnold L. Demain

1970 ◽  
Vol 21 (3) ◽  
pp. 493 ◽  
Author(s):  
GW Lanigan ◽  
LW Smith

In vitro studies have demonstrated that the rate of metabolism of pyrrolizidine alkaloids in sheep's rumen fluid varies greatly. Fluids from sheep at pasture display much higher activity than do those from chaff-fed animals. Addition of dried Heliotropium europaeum to a chaff ration leads to a marked increase in the in vitro rate of alkaloid degradation by the rumen fluid but activity rapidly declines again when the H. europaeum is withdrawn. Thus a major factor limiting multiplication in the rumen of bacteria responsible for alkaloid breakdown appears to be lack of their specific substrates. N-oxides of pyrrolizidine alkaloids are rapidly reduced to tertiary bases in rumen fluid, even in samples from sheep not previously exposed to these substrates. The stimulation of the alkaloid-metabolizing system by vitamin B12 also varies greatly, both in whole rumen fluid and in fluids with activity reduced by removal of coarsely particulate matter. It is concluded that the B12 effect is not related to a specific requirement of the alkaloid-utilizing bacteria but to stimulation of other species which produce a metabolite essential for pyrrolizidine alkaloid metabolism.


1998 ◽  
Vol 17 (1) ◽  
pp. 49-53
Author(s):  
Hiroko NODA ◽  
Shoko FUKUDA ◽  
Tokumitsu OKAMURA ◽  
Masahiro OSUGI

PEDIATRICS ◽  
1958 ◽  
Vol 21 (5) ◽  
pp. 860-864
Author(s):  

The great mass of information on the beneficial influence of thiamine in markedly deficient animals is probably not applicable to any but the most severely deprived humans. No secure data are at hand that thiamine administration to humans "stimulates" appetite; this does not conflict with the well-recognized fact that the vitamin is essential for body processes. The evidence for appetite-stimulating or growth-promoting effects of vitamin B12 is not convincing. Whatever the specific medical or nutritional indications for vitamin B12 may prove to be, in children, it is clean that this vitamin does not encourage appetite so as to cause increased growth in children. Admitting that the design of experimental work with humans is fraught with difficulties, the lack of scientifically acceptable control subjects makes much of the evidence advanced in support of specific effects of vitamin B12 unacceptable. The impression should not be conveyed to the physician that "growth failure" is commonplace and that all flagging appetites are due to inadequate intake of either on both of these vitamins. On the basis of current knowledge, claims for any effect of these vitamins in either stimulating appetite or promoting growth are not justified. Present evidence is insufficient to show any effect of vitamin B1 and vitamin B12 on stimulation of appetite or growth except in deficiency states. This discussion in no way detracts from the metabolic significance or usefulness of these two important vitamins. It is clear that, at present, we do not yet fully understand appetite or all the factors which affect growth. Humility should govern the attitudes of manufacturers and physicians alike when it is urged that growth-promoting substances be given to large groups of children.


PEDIATRICS ◽  
1958 ◽  
Vol 22 (6) ◽  
pp. 1202-1203
Author(s):  
E. E. HOWE

I have read the report of the Committee on Nutrition (Pediatrics, 21:860, 1958) appraising the use of vitamins B1 and B12 as supplements for the stimulation of growth and appetite in children with a great deal of interest. My own interest in this area has been centered on vitamin B12 and my comments will be limited to the studies with this vitamin. I think anyone who has studied the literature on this subject carefully, realizes the complexity of the problem and the difficulties that are involved in its evaluation.


Author(s):  
E. A. Elfont ◽  
R. B. Tobin ◽  
D. G. Colton ◽  
M. A. Mehlman

Summary5,-5'-diphenyl-2-thiohydantoin (DPTH) is an effective inhibitor of thyroxine (T4) stimulation of α-glycerophosphate dehydrogenase in rat liver mitochondria. Because this finding indicated a possible tool for future study of the mode of action of thyroxine, the ultrastructural and biochemical effects of DPTH and/or thyroxine on rat liver mere investigated.Rats were fed either standard or DPTH (0.06%) diet for 30 days before T4 (250 ug/kg/day) was injected. Injection of T4 occurred daily for 10 days prior to sacrifice. After removal of the liver and kidneys, part of the tissue was frozen at -50°C for later biocheailcal analyses, while the rest was prefixed in buffered 3.5X glutaraldehyde (390 mOs) and post-fixed in buffered 1Z OsO4 (376 mOs). Tissues were embedded in Araldlte 502 and the sections examined in a Zeiss EM 9S.Hepatocytes from hyperthyroid rats (Fig. 2) demonstrated enlarged and more numerous mitochondria than those of controls (Fig. 1). Glycogen was almost totally absent from the cytoplasm of the T4-treated rats.


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