Norwegian
Radiation Protection Authority
|
| Photosensitizing effects
metalloporphyns in connection with hyperbilirubinemia
| Metalloporphyrin concentration
|
Light
dose (E/m2) |
D |
| 0 uM |
1 |
0.9 |
| 32 mM ZnPP |
1 |
0 |
| 32 mM SnPP |
1 |
0.8 |
| 5 mM ZnPP |
0.015 |
0.55 |
| 10 mM ZnPP |
0.015 |
0.10 |
| 10 mM SnPP |
0.23 |
0.85 |
| 130 mM SnPP |
0.23 |
0.60 |
Table I. The
induction of strand breaks and alkali labile sites by
blue light in TMG-1 cells pre-incubated for 1 h with the
metalloporphyrins. D; "Fraction double stranded
DNA", represents the fraction of the DNA that is
double stranded after an unwinding procedure in 0.1 N
NaOH.
| PORPHYRIN |
DOSE,
(E/m2)
|
RATE
CONST., k (m2/E) |
| CrPP |
0.14 |
0.26 |
| - |
0.56 |
0.13 |
| - |
1.12 |
0.21 |
| - |
1.68 |
0.15 |
| CrMP |
0.14 |
0.15 |
| - |
0.56 |
0.15 |
| - |
1.12 |
0.15 |
| - |
1.68 |
0.13 |
| SnPP |
0.14 |
5.48 |
| ZnPP |
0.14 |
9.29 |
| HP |
0.14 |
1.38 |
| PP |
0.14 |
1.59 |
Table II:
Photooxidation of tryptophan in the presence of 2 mM porphyrin at pH 12. The
reduction of fluorescence from tryptophan was measured in
two samples per dose. It was assumed that the reduction
in fluorescence relative to unirradiated control samples
is proportional to e-kD
(dose of blue light: D) and the rate constants (k) were
calculated. The values of k in the table, are the mean of
two determinations.
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Figure 1:
 Fluorescence
micrographs of a group of TMG-1 cells incubated
with 10 mM ZnPP for 1 h.
Upper left: Fluorescence from ZnPP excited at 450
- 490 nm.
Upper right: Fluorescence from Hoechst 33258
binding to the nucleus, excited at 340 nm
Lower left: Manipulated picture showing both
ZnPP- and Hoechst 33258-fluorescence overlaying a
phase contrast picture of the same cells.
Lower right: The same as lower left, with edge
enhancement, indicating subcellular structures.
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Figure 2:
 The effect of light,
metalloporphyrins and bilirubin on the survival
of 308 mouse epidermis cells. The cells were
pre-incubated with 5 mM metalloporphyrins
for 1 h. Samples labelled control were not
labelled with metalloporphyrins. The irradiation
took place in a PBS solution of 10 mM BSA or in a PBS
solution of 10 mM BSA with 10 mM bilirubin (labelled
BR). Neither metalloporphyrins nor bilirubin were
toxic in the dark under the conditions used.
Based on three determinations of survival
(standard error was always less than 0.2).
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