Limits...
The effect of ranibizumab versus photodynamic therapy on DNA damage in patients with exudative macular degeneration.

Mozaffarieh M, Schötzau A, Josifova T, Flammer J - Mol. Vis. (2009)

Bottom Line: DNA breaks lead to smaller pieces of DNA, which in an electrical field, migrate out of the nucleus forming a tail.Comparisons between time points and study groups were assessed using a linear mixed-effect model.This increase was significant (p=0.004).

View Article: PubMed Central - PubMed

Affiliation: University Eye Clinic, Basel, Switzerland.

ABSTRACT

Purpose: To compare the effect of ranibizumab treatment versus photodynamic therapy (PDT) on single-stranded DNA damage in circulating leukocytes in patients with exudative age-related macular degeneration (AMD).

Methods: A comparative quantification of single-stranded DNA breaks was performed in circulating leukocytes of AMD patients before and 30 min, 45 min, 60 min, and 24 h after two different modes of therapy: a) PDT; and b) intravitreal ranibizumab injection. DNA breaks lead to smaller pieces of DNA, which in an electrical field, migrate out of the nucleus forming a tail. Damage of an individual cell was quantified as a comet tail moment. The proportion of non-zero values compared to the total number of observations was referred to as "amount of DNA damage" expressed in arbitrary units (AU). Comparisons between time points and study groups were assessed using a linear mixed-effect model.

Results: PDT induced an increase in the amount of single-stranded DNA damage in the circulating leukocytes from 0.2 AU (before treatment) to 0.53 AU (30 min after treatment). This increase was significant (p=0.004). In contrast, after ranibizumab treatment, the DNA damage in the circulating leukocytes remained unchanged.

Conclusions: PDT purposely induces a local oxidative stress to damage the newly formed vessels. Our results indicate an additional systemic oxidative stress, apparent as amount of single-stranded DNA damage in the circulating leukocytes, for at least 30 min after treatment.

Show MeSH

Related in: MedlinePlus

Photographs of cells analyzed by comet assay analysis. A: Photograph A depicts intact cells (without tail) of a patient treated with ranimizumab. B: Photograph B depicts cells of a patient 30 min after treatment with PDT. Arrowhead points to a typical “comet” with a bright head and tail.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2697459&req=5

f1: Photographs of cells analyzed by comet assay analysis. A: Photograph A depicts intact cells (without tail) of a patient treated with ranimizumab. B: Photograph B depicts cells of a patient 30 min after treatment with PDT. Arrowhead points to a typical “comet” with a bright head and tail.

Mentions: Gel electrophoresis separates damaged DNA from undamaged DNA. This method has previously been described in detail in the literature [15]. The cells under study were embedded in agarose on a slide and subjected to lysis followed by electrophoresis under specific conditions. DNA is negatively charged, in particular, in alkaline conditions. When put in an electrical field, the intact DNA was such a large molecule that it hardly moved. DNA breaks, however, lead to smaller pieces of DNA which migrated away from the intact DNA. The amount of migrated DNA was the measure of the extent of DNA damage. To detect DNA, the slides were stained with cyber-green and examined by fluorescence microscopy equipped with a personal computer based analysis system (Kinetic Imaging; Nikon, Zürich, Switzerland), which enabled quantification of DNA damage. Cells containing damaged DNA had the appearance of a comet with a bright head (undamaged) and tail (damaged; Figure 1).


The effect of ranibizumab versus photodynamic therapy on DNA damage in patients with exudative macular degeneration.

Mozaffarieh M, Schötzau A, Josifova T, Flammer J - Mol. Vis. (2009)

Photographs of cells analyzed by comet assay analysis. A: Photograph A depicts intact cells (without tail) of a patient treated with ranimizumab. B: Photograph B depicts cells of a patient 30 min after treatment with PDT. Arrowhead points to a typical “comet” with a bright head and tail.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2697459&req=5

f1: Photographs of cells analyzed by comet assay analysis. A: Photograph A depicts intact cells (without tail) of a patient treated with ranimizumab. B: Photograph B depicts cells of a patient 30 min after treatment with PDT. Arrowhead points to a typical “comet” with a bright head and tail.
Mentions: Gel electrophoresis separates damaged DNA from undamaged DNA. This method has previously been described in detail in the literature [15]. The cells under study were embedded in agarose on a slide and subjected to lysis followed by electrophoresis under specific conditions. DNA is negatively charged, in particular, in alkaline conditions. When put in an electrical field, the intact DNA was such a large molecule that it hardly moved. DNA breaks, however, lead to smaller pieces of DNA which migrated away from the intact DNA. The amount of migrated DNA was the measure of the extent of DNA damage. To detect DNA, the slides were stained with cyber-green and examined by fluorescence microscopy equipped with a personal computer based analysis system (Kinetic Imaging; Nikon, Zürich, Switzerland), which enabled quantification of DNA damage. Cells containing damaged DNA had the appearance of a comet with a bright head (undamaged) and tail (damaged; Figure 1).

Bottom Line: DNA breaks lead to smaller pieces of DNA, which in an electrical field, migrate out of the nucleus forming a tail.Comparisons between time points and study groups were assessed using a linear mixed-effect model.This increase was significant (p=0.004).

View Article: PubMed Central - PubMed

Affiliation: University Eye Clinic, Basel, Switzerland.

ABSTRACT

Purpose: To compare the effect of ranibizumab treatment versus photodynamic therapy (PDT) on single-stranded DNA damage in circulating leukocytes in patients with exudative age-related macular degeneration (AMD).

Methods: A comparative quantification of single-stranded DNA breaks was performed in circulating leukocytes of AMD patients before and 30 min, 45 min, 60 min, and 24 h after two different modes of therapy: a) PDT; and b) intravitreal ranibizumab injection. DNA breaks lead to smaller pieces of DNA, which in an electrical field, migrate out of the nucleus forming a tail. Damage of an individual cell was quantified as a comet tail moment. The proportion of non-zero values compared to the total number of observations was referred to as "amount of DNA damage" expressed in arbitrary units (AU). Comparisons between time points and study groups were assessed using a linear mixed-effect model.

Results: PDT induced an increase in the amount of single-stranded DNA damage in the circulating leukocytes from 0.2 AU (before treatment) to 0.53 AU (30 min after treatment). This increase was significant (p=0.004). In contrast, after ranibizumab treatment, the DNA damage in the circulating leukocytes remained unchanged.

Conclusions: PDT purposely induces a local oxidative stress to damage the newly formed vessels. Our results indicate an additional systemic oxidative stress, apparent as amount of single-stranded DNA damage in the circulating leukocytes, for at least 30 min after treatment.

Show MeSH
Related in: MedlinePlus