scholarly journals Ribonucleotide reductase activity in vitamin B12-deficient Euglena gracilis

1980 ◽  
Vol 188 (2) ◽  
pp. 573-576 ◽  
Author(s):  
E F Carell ◽  
J W Seeger
Keyword(s):  
Vitamin B12 ◽  
Ribonucleotide Reductase ◽  
Euglena Gracilis ◽  
Reductase Activity ◽  
Vitamin B12 Deficiency ◽  
Growth Conditions ◽  
Maximum Value ◽  
B12 Deficiency ◽  
Increased Activity ◽  
Ribonucleotide Reductase Activity

The ribonucleotide reductase activities in vitamin B12-sufficient and -deficient cells of Euglena gracilis were measured. We found that the cells progress into vitamin B12 deficiency the enzyme activity increases, reaching a maximum value of 20-fold in advanced deficiency. No signigicant differences in the activities were found to result as a consequence of different growth conditions. We propose that the increased activity in vitamin B12-deficient cells is due to an increase in enzyme protein.

scholarly journals STUDIES ON CHLOROPLAST DEVELOPMENT AND REPLICATION IN EUGLENA

1969 ◽  
Vol 41 (2) ◽  
pp. 431-440 ◽  
Author(s):  
Edgar F. Carell
Keyword(s):  
Cell Division ◽  
Vitamin B12 ◽  
Euglena Gracilis ◽  
Chloroplast Development ◽  
Vitamin B12 Deficiency ◽  
Normal Growth ◽  
Cell Protein ◽  
Chloroplast Replication ◽  
B12 Deficiency ◽  
Cellular Replication

When Euglena gracilis is grown under vitamin B12 deficiency conditions, the amount of protein and of chlorophyll per cell increase with decrease of B12 in the medium and consequently in the cell. The increase in cell protein is proportional to and precedes an increase in the number of chloroplasts per cell. This replication of the chloroplasts under deficiency conditions is not accompanied by nuclear or cell division. It is concluded that chloroplast replication in Euglena gracilis is independent of nuclear and cellular replication, at least under B12 deficiency conditions. We established a graph of the growth of Euglena under different concentrations of vitamin B12 added to the growth medium, which permitted us to calculate that at least 22,000 molecules of vitamin B12 per cell are required to give normal growth.

55: The Risk of Vitamin B12 Deficiency is Low after Ileal Orthotopic Bladder Substitution

2004 ◽  
Vol 171 (4S) ◽  
pp. 15-15
Author(s):  
Urs E. Studer ◽  
Richard Aebischer ◽  
Katharina Ochsner ◽  
Werner W. Hochreiter
Keyword(s):  
Vitamin B12 ◽  
Vitamin B12 Deficiency ◽  
B12 Deficiency ◽  
Bladder Substitution

Bioavailability of Vitamin B12

2010 ◽  
Vol 80 (45) ◽  
pp. 330-335 ◽  
Author(s):  
Lindsay Helen Allen
Keyword(s):  
Vitamin B12 ◽  
Vitamin B12 Deficiency ◽  
The Elderly ◽  
Radioactive Isotopes ◽  
Animal Source Foods ◽  
Dietary Requirements ◽  
In Vivo Labeling ◽  
B12 Deficiency ◽  
Vitamin B12 Malabsorption

Vitamin B12 deficiency is common in people of all ages who consume a low intake of animal-source foods, including populations in developing countries. It is also prevalent among the elderly, even in wealthier countries, due to their malabsorption of B12 from food. Several methods have been applied to diagnose vitamin B12 malabsorption, including Schilling’s test, which is now used rarely, but these do not quantify percent bioavailability. Most of the information on B12 bioavailability from foods was collected 40 to 50 years ago, using radioactive isotopes of cobalt to label the corrinoid ring. The data are sparse, and the level of radioactivity required for in vivo labeling of animal tissues can be prohibitive. A newer method under development uses a low dose of radioactivity as 14C-labeled B12, with measurement of the isotope excreted in urine and feces by accelerator mass spectrometry. This test has revealed that the unabsorbed vitamin is degraded in the intestine. The percent bioavailability is inversely proportional to the dose consumed due to saturation of the active absorption process, even within the range of usual intake from foods. This has important implications for the assessment and interpretation of bioavailability values, setting dietary requirements, and interpreting relationships between intake and status of the vitamin.

Increased monocyte to HDL cholesterol ratio in vitamin B12 deficiency: is it related to cardiometabolic risk?

2020 ◽  
pp. 1-8
Author(s):  
Sanem Kayhan ◽  
Nazli Gulsoy Kirnap ◽  
Mercan Tastemur
Keyword(s):  
Risk Factors ◽  
Blood Pressure ◽  
Uric Acid ◽  
Vitamin B12 ◽  
Cardiometabolic Risk ◽  
Vitamin B12 Deficiency ◽  
Left Ventricular ◽  
Cardiometabolic Risk Factors ◽  
B12 Deficiency ◽  
Deficiency Group

Abstract. Vitamin B12 deficiency may have indirect cardiovascular effects in addition to hematological and neuropsychiatric symptoms. It was shown that the monocyte count-to-high density lipoprotein cholesterol (HDL-C) ratio (MHR) is a novel cardiovascular marker. In this study, the aim was to evaluate whether MHR was high in patients with vitamin B12 deficiency and its relationship with cardiometabolic risk factors. The study included 128 patients diagnosed with vitamin B12 deficiency and 93 healthy controls. Patients with vitamin B12 deficiency had significantly higher systolic blood pressure (SBP), diastolic blood pressure (DBP), MHR, C-reactive protein (CRP) and uric acid levels compared with the controls (median 139 vs 115 mmHg, p < 0.001; 80 vs 70 mmHg, p < 0.001; 14.2 vs 9.5, p < 0.001; 10.2 vs 4 mg/dl p < 0.001; 6.68 vs 4.8 mg/dl, p < 0.001 respectively). The prevalence of left ventricular hypertrophy was higher in vitamin B12 deficiency group (43.8%) than the control group (8.6%) (p < 0.001). In vitamin B12 deficiency group, a positive correlation was detected between MHR and SBP, CRP and uric acid (p < 0.001 r:0.34, p < 0.001 r:0.30, p < 0.001 r:0.5, respectively) and a significant negative correlation was detected between MHR and T-CHOL, LDL, HDL and B12 (p < 0.001 r: −0.39, p < 0.001 r: −0.34, p < 0.001 r: −0.57, p < 0.04 r: −0.17, respectively). MHR was high in vitamin B12 deficiency group, and correlated with the cardiometabolic risk factors in this group, which were SBP, CRP, uric acid and HDL. In conclusion, MRH, which can be easily calculated in clinical practice, can be a useful marker to assess cardiovascular risk in patients with vitamin B12 deficiency.

Utility of measuring vitamin B12 and its active fraction, holotranscobalamin, in neurological vitamin B12 deficiency syndromes

2009 ◽  
Vol 36 (S 02) ◽  
Author(s):  
W Schrempf ◽  
V Neumeister ◽  
M Eulitz ◽  
G Siegert ◽  
H Reichmann ◽  
...  
Keyword(s):  
Vitamin B12 ◽  
Vitamin B12 Deficiency ◽  
Active Fraction ◽  
B12 Deficiency

Vitamin B12 Deficiency; a Silent Northside Dublin Epidemic?

Endoscopy ◽  
2006 ◽  
Vol 38 (11) ◽  
Author(s):  
CP O'Brien ◽  
S Patchett
Keyword(s):  
Vitamin B12 ◽  
Vitamin B12 Deficiency ◽  
B12 Deficiency
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