Biomedical subjects

Victoria Simon

Publications and source records attributed to Victoria Simon.

3 recordsLinked to original sources

PubMed2026

Excess folate elevates formaldehyde genotoxicity in cell lines but not in mice or humans.

Folate metabolites are chemically unstable: spontaneous decomposition releases formaldehyde, a genotoxin in blood stem cells and a human carcinogen. Despite this, folic acid consumption frequently exceeds the Recommended Dietary Allowance and is prescribed at high doses for patients with blood disorders. However, the impact of excess folate on endogenous formaldehyde genotoxicity in vivo has not been studied. We find that excess tetrahydrofolate (THF) treatment of cell lines elevates formaldehyde-DNA adducts and genotoxicity. To test this in vivo, we fed a high-folic acid diet (10-fold above standard) to mice with heightened sensitivity to formaldehyde: detoxification-impaired Adh5-/- mice, and Fanconi anemia DNA repair mutants Fanca-/- and Fancj-/-. In contrast to cell lines, elevated tissue THF was not associated with increased formaldehyde-DNA adducts nor blood stem cell attrition. Finally, in cancer patients, high-dose folic acid therapy elevated plasma folic acid but did not increase formaldehyde-DNA adducts in peripheral blood mononuclear cells. In conclusion, increased folate in vivo does not elevate endogenous formaldehyde genotoxicity in sensitized mouse models or humans.

Animals↗

PubMed2006

Characterising Māori nursing practice.

This paper summarises research which addresses the question What might constitute Māori nursing practice? The research design adopted was influenced by Kaupapa Māori methodology and used a semi-structured, qualitative, in-depth interview process. It was found that by understanding the current experiences of Māori registered nurses, their reflections on their preparation for practice, and their current practice, we are able to identify the present and future training and practice needs of Māori nurses. Māori nursing practice can be characterised as having five features: the promotion of cultural affirmation including cultural awareness and identity; the support of, and access to Māori networks; the adoption of Māori models of health; the enabling of visibility and pro-activity as Māori nurses; and, the validation of Māori nurses as effective health professionals. Three recommendations for promoting Māori nursing practice are made in relation to staff in the workplace and in nurse education programmes. All nursing staff need to be alert to: 1. The impact of western scientific models on Māori healthcare; 2. The (often passive) non-acceptance of Māori within mainstream institutions; and 3. The benefits of valuing Indigenous nursing programmes.

Awareness↗

PubMed2002

Osteocalcin and myoglobin removal in on-line hemodiafiltration versus low- and high-flux hemodialysis.

BACKGROUND: Removal of medium and large solutes is poor with low-flux (LF-HD) and limited with high-flux hemodialysis (HF-HD) and on-line hemodiafiltration (OL-HDF). In clinical practice, there are few in vivo solute markers. Osteocalcin is a protein with a molecular mass of 5,800 daltons, and myoglobin is a large molecule with a molecular mass of 17,200 daltons. The aim of this study was to evaluate the impact of OL-HDF on in vivo removal of a wide spectrum of solutes (urea, creatinine, osteocalcin, beta2-microglobulin, and myoglobin) in comparison to LF-HD and HF-HD. METHODS: Twenty-three patients (15 men, 8 women) were studied. Every patient underwent three dialysis sessions with routine HD parameters. We compared 1.8-m2 polysulfone LF-HD and 1.8-m2 polysulfone HF-HD versus OL-HDF. Predialysis and postdialysis solute concentrations were measured. The percentage of reduction ratio for each solute was calculated. RESULTS: Mean values for predialysis osteocalcin, beta2-microglobulin, and myoglobin were 16.3 +/- 21 ng/mL, 27.4 +/- 5 mg/L, and 239 +/- 162 ng/mL in LF-HD, respectively. Urea and creatinine reduction ratios were similar in LF-HD and HF-HD and only 1.2% higher in OL-HDF. Osteocalcin, beta2-microglobulin, and myoglobin reduction ratios for LF-HD were negligible. Mean osteocalcin reduction rates were 54.2% +/- 12% for HF-HD versus 63.5% +/- 9% for OL-HDF (reinfusion volume, 26.8 +/- 5 L/session; P < 0.01). Mean beta2-microglobulin reduction rates were 60.1% +/- 9% for HF-HD versus 75.4% +/- 9% for OL-HDF (P < 0.01). Mean myoglobin reduction rates were 24.5% +/- 6% and 62.7% +/- 9% for HF-HD and OL-HDF, respectively (P < 0.01). CONCLUSION: LF-HD does not seem to remove solutes with a molecular weight greater than 5,800 daltons. OL-HDF provides marked enhancement of convection volume and enables a significant increase in osteocalcin and beta2-microglobulin removal. Myoglobin extraction is nil with LF-HD, very low with HF-HD, and only adequate with OL-HDF.

Adult↗