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Study Information
Study Attribute Value
CEBS Accession Number: 002-01528-0001-0000-9
Chemical Name: 5,6-Dihydro-5-azacytidine
CASRN: 62488-57-7
NTP Study Type: Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID: 450014
Study Result: Positive


Table Instructions and Notes:
Studies are indicated to be "Nontoxic" when the observed reductions in relative total growth did not indicate that the maximum tolerated dose was achieved.

Nonactivation Trial: 1 Experiment Call: Positive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Fischer Medium 
 0         
 100 89 57 19 19
    91 118 41 15
    94 95 58 21
    84 98 55 22
Test Chemical 5,6-Dihydro-5-azacytidine 
1.5       
 87 77 61 23 21
    92 92 51 19
  
4.5       
 91 83 85 31 32*
    75 68 72 32
  
15         
 69 43 114 55 48*
    80 53 98 41
  
45         
 48 21 45 32 40*
    40 22 59 49
  
150         
 45 8 43 32 35*
    34 5 38 38
  
450         
   
Positive Control Methyl Methane Sulfonate 
15         
 42 25 178 142 145*
    42 19 188 148

Nonactivation Trial: 2 Experiment Call: Positive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Fischer Medium 
 0         
 98 96 43 15 16
    93 109 25 9
    102 96 92 30
    92# 100 32 12
Test Chemical 5,6-Dihydro-5-azacytidine 
1.5       
 84 80 73 29 32*
    101 96 107 35
  
4.5       
 68 74 83 41 42*
    85 77 111 43
  
15         
 52 45 99 63 67*
    42 45 88 70
  
45         
 22 9 49 74 76*
    29 10 68 78
  
150         
 7r 1 23 107
    6r 0 11 59
  
450         
   
Positive Control Methyl Methane Sulfonate 
15         
 39 25 118 101 129*
    32 20 150 157

Nonactivation Trial: 3 Experiment Call: Positive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Fischer Medium 
 0         
 70 97 44 21 23
    75 108 56 25
    69 98 44 21
    68 97 47 23
Test Chemical 5,6-Dihydro-5-azacytidine 
 0.25      
 66# 81 56 28 26
    75 81 51 23
  
 0.5       
 75 95 63 28 26
    70 95 50 24
  
1         
 70 78 80 38 35
    65 94 62 32
  
2         
 69 71 94 46 43*
    60 78 73 40
  
4         
 60 71 115 64 62*
    71 75 127 60
  
8         
 60 68 130 73 72*
    62 65 133 72
Positive Control Methyl Methane Sulfonate 
15         
 26 19 158 207 215*
    28 21 184 223

Footnotes:
Asterisks(*) indicate significant responses.
r = rejected value due to quality control criteria
# = reduced sample size because of the loss of one culture dish due to contamination