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Post-collection, pre-measurement variables affecting VEGF levels in urine biospecimens.

Hayward RM, Kirk MJ, Sproull M, Scott T, Smith S, Cooley-Zgela T, Crouse NS, Citrin DE, Camphausen K - J. Cell. Mol. Med. (2008 Jan-Feb)

Bottom Line: The results of this study indicate that time to freeze up to 4 hrs, number of freeze-thaw cycles between one and five, and different types of polypropylene tubes did not have statistically significant effects on measured urinary VEGF levels.Urinary sediment had higher VEGF levels than supernatant in five of six samples from healthy patients.It is not clear whether there is an active agent in the sediment causing this increase or if the sediment particles themselves are affecting the accuracy of the assay.Therefore, we recommend centrifuging urine, isolating the supernatant, and freezing the sample in polypropylene microcentrifuge tubes or cryogenic vials within 4 hrs of collection.In addition, we recommend the use of samples within five freeze-thaw cycles.

View Article: PubMed Central - PubMed

Affiliation: Radiation Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892-1002, USA.

ABSTRACT
Angiogenesis, the development and recruitment of new blood vessels, plays an important role in tumour growth and metastasis. Vascular endothelial growth factor (VEGF) is an important stimulator of angiogenesis. Circulating and urinary VEGF levels have been suggested as clinically useful predictors of tumour behaviour, and investigations into these associations are ongoing. Despite recent interest in measuring VEGF levels in patients, little is known about the factors that influence VEGF levels in biospecimens. To begin to address this question, urine samples were collected from patients with solid tumours undergoing radiotherapy and healthy volunteers. Four factors were examined for their effects on VEGF concentrations as measured by chemiluminescent immunoassay: time from sample collection to freezing, number of specimen freeze-thaw cycles, specimen storage tube type and the inclusion or exclusion of urinary sediment. The results of this study indicate that time to freeze up to 4 hrs, number of freeze-thaw cycles between one and five, and different types of polypropylene tubes did not have statistically significant effects on measured urinary VEGF levels. Urinary sediment had higher VEGF levels than supernatant in five of six samples from healthy patients. It is not clear whether there is an active agent in the sediment causing this increase or if the sediment particles themselves are affecting the accuracy of the assay.Therefore, we recommend centrifuging urine, isolating the supernatant, and freezing the sample in polypropylene microcentrifuge tubes or cryogenic vials within 4 hrs of collection.In addition, we recommend the use of samples within five freeze-thaw cycles.

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Related in: MedlinePlus

The change in urinary VEGF concentration from 1 to 2, 3, 4, and 5 freeze–thaw cycles for nine cancer patients.() Mean value (n= 3); (error bars) 95% confidence interval.
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fig02: The change in urinary VEGF concentration from 1 to 2, 3, 4, and 5 freeze–thaw cycles for nine cancer patients.() Mean value (n= 3); (error bars) 95% confidence interval.

Mentions: Measured VEGF levels were not statistically related to the number of freeze–thaw cycles between one and five (Fig. 2). Likewise, there was no statistically significant difference in VEGF levels between any two freeze–thaw cycles (Table 2).


Post-collection, pre-measurement variables affecting VEGF levels in urine biospecimens.

Hayward RM, Kirk MJ, Sproull M, Scott T, Smith S, Cooley-Zgela T, Crouse NS, Citrin DE, Camphausen K - J. Cell. Mol. Med. (2008 Jan-Feb)

The change in urinary VEGF concentration from 1 to 2, 3, 4, and 5 freeze–thaw cycles for nine cancer patients.() Mean value (n= 3); (error bars) 95% confidence interval.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2367114&req=5

fig02: The change in urinary VEGF concentration from 1 to 2, 3, 4, and 5 freeze–thaw cycles for nine cancer patients.() Mean value (n= 3); (error bars) 95% confidence interval.
Mentions: Measured VEGF levels were not statistically related to the number of freeze–thaw cycles between one and five (Fig. 2). Likewise, there was no statistically significant difference in VEGF levels between any two freeze–thaw cycles (Table 2).

Bottom Line: The results of this study indicate that time to freeze up to 4 hrs, number of freeze-thaw cycles between one and five, and different types of polypropylene tubes did not have statistically significant effects on measured urinary VEGF levels.Urinary sediment had higher VEGF levels than supernatant in five of six samples from healthy patients.It is not clear whether there is an active agent in the sediment causing this increase or if the sediment particles themselves are affecting the accuracy of the assay.Therefore, we recommend centrifuging urine, isolating the supernatant, and freezing the sample in polypropylene microcentrifuge tubes or cryogenic vials within 4 hrs of collection.In addition, we recommend the use of samples within five freeze-thaw cycles.

View Article: PubMed Central - PubMed

Affiliation: Radiation Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892-1002, USA.

ABSTRACT
Angiogenesis, the development and recruitment of new blood vessels, plays an important role in tumour growth and metastasis. Vascular endothelial growth factor (VEGF) is an important stimulator of angiogenesis. Circulating and urinary VEGF levels have been suggested as clinically useful predictors of tumour behaviour, and investigations into these associations are ongoing. Despite recent interest in measuring VEGF levels in patients, little is known about the factors that influence VEGF levels in biospecimens. To begin to address this question, urine samples were collected from patients with solid tumours undergoing radiotherapy and healthy volunteers. Four factors were examined for their effects on VEGF concentrations as measured by chemiluminescent immunoassay: time from sample collection to freezing, number of specimen freeze-thaw cycles, specimen storage tube type and the inclusion or exclusion of urinary sediment. The results of this study indicate that time to freeze up to 4 hrs, number of freeze-thaw cycles between one and five, and different types of polypropylene tubes did not have statistically significant effects on measured urinary VEGF levels. Urinary sediment had higher VEGF levels than supernatant in five of six samples from healthy patients. It is not clear whether there is an active agent in the sediment causing this increase or if the sediment particles themselves are affecting the accuracy of the assay.Therefore, we recommend centrifuging urine, isolating the supernatant, and freezing the sample in polypropylene microcentrifuge tubes or cryogenic vials within 4 hrs of collection.In addition, we recommend the use of samples within five freeze-thaw cycles.

Show MeSH
Related in: MedlinePlus