Biomedical subjects

Daisy E Kaempf-Rotzoll

Publications and source records attributed to Daisy E Kaempf-Rotzoll.

3 recordsLinked to original sources

PubMed2003

Influence of long-chain polyunsaturated fatty acid formula feeds on vitamin E status in preterm infants.

It has been recommended to supplement formulas for preterm infants with n-3 and n-6 long-chain polyunsaturated fatty acids (LCP) to improve growth, visual acuity, and neurodevelopmental performance. However, large amounts of LCP may increase lipid peroxidation and oxidative stress in preterm infants. We investigated if, under high supplementation of natural tocopherols, LCP addition to formula can be performed safely without causing tocopherol depletion in cell membranes. Thirty-one healthy preterm infants with gestational ages from 28 to 32 weeks were evaluated in a prospective, randomized study from birth to day 42. Nine infants received an n-3 and n-6 LCP-enriched formula (A), eleven infants a standard formula (B), and eleven infants breast milk (control group). Alpha- and gamma-tocopherol extracts were added to both formulas, amounting to five times the value in breast milk (2.3 mg/dL in both formulas versus 0.45 mg/dL in breast milk). Erythrocyte arachidonic acid (AA) and docosahexaenoic acid (DHA) in the phosphatidylethanolamine fraction were similar in the three groups over the study period, whereas a significant reduction of erythrocyte AA and DHA could be detected in the phosphatidylcholine fraction in all three groups from day 14 onwards, when compared to respective cord blood values, with lowest values in the standard formula group. Amazingly, levels of alpha- and gamma-tocopherol were higher in plasma, erythrocytes, platelets, monocytes, and polymorphonuclear leukocytes with LCP supplementation as compared to standard formula and breast milk from day 7 onwards, whereas in buccal mucosal cells, this was not the case until day 42. Gammatocopherol uptake in the LCP-supplemented group was also significantly higher in all cell fractions studied from day 7 onwards. We therefore hypothesize that the LCP supplementation used in formula A improves tocopherol solubility and stability in biological membranes. Under high-dose vitamin E addition to n-3 and n-6 LCP-supplemented formula, no evidence for tocopherol depletion and furthermore, high accumulation of tocopherols, can be detected in healthy preterm infants.

Antioxidants↗

PubMed2003

pH-dependent translocation of alpha-tocopherol transfer protein (alpha-TTP) between hepatic cytosol and late endosomes.

BACKGROUND: alpha-Tocopherol transfer protein (alpha-TTP), a member of the Sec14 protein family, plays an important role in transporting alpha-tocopherol, a major lipid-soluble anti-oxidant, in the cytosolic compartment of hepatocytes and is known as a product of the causative gene for familial isolated vitamin E deficiency. It has been shown that the secretion of hepatocyte alpha-tocopherol taken up with plasma lipoproteins is facilitated by alpha-TTP. To explore the mechanism of alpha-TTP mediated alpha-tocopherol secretion, we investigated drugs which may affect this secretion. RESULTS: We found that, in a hepatocyte cell culture system, intracellular alpha-tocopherol transport is impaired by chloroquine, an agent known for its function of elevating the pH in acidic compartments. Under chloroquine treatment, the diffuse cytosolic distribution of alpha-TTP changes to a punctate pattern. Double-staining experiments with endocytosis markers revealed that alpha-TTP accumulates transiently on the cytoplasmic surface of late endosomal membranes. This phenomenon is specific for hepatoma cell lines or primarily cultured hepatocytes. Other members of the Sec14 family, such as cellular retinaldehyde-binding protein (CRALBP) and supernatant protein factor (SPF), do not show this accumulation. Furthermore, we elucidate that the obligatory amino acid sequence for this function is located between amino acids 21 and 50, upstream of the N-terminal end of the lipid-binding domain. CONCLUSION: We hypothesize that a liver-specific target molecule for alpha-TTP exists on the late endosomal membrane surface. This transient binding may explain the mechanism of how alpha-tocopherol is transferred from late endosomes to cytosolic alpha-TTP.

Amino Acid Sequence↗

PubMed2003

Vitamin E and transfer proteins.

PURPOSE OF REVIEW: Recently, the intracellular transport as well as cellular uptake and excretion of alpha-tocopherol, the major representative of vitamin E, have been elucidated. RECENT FINDINGS: Alpha-tocopherol transfer protein has been identified as the major intracellular transport protein for vitamin E, mediating alpha-tocopherol secretion into the plasma via a non-Golgi-dependent pathway, while other binding proteins seem to play a less important role. New information has accumulated concerning the role of this protein in the transport and supply of vitamin E to tissues such as the central nervous system and the feto-maternal unit. The scavenger receptor class B type I receptor, a membrane-bound protein, is capable of transferring vitamin E into the cell, while the ATP-binding cassette transporter A1 can excrete vitamin E out of the cell. Advances in the area of vitamin E metabolism have shown that alpha-CEHC (2,5,7,8-tetramethyl-2-(2'-carboxyethyl)-6-hydroxychroman) and gamma-CEHC (2,7,8-trimethyl-2-(2'-carboxyethyl)-6-hydroxychroman) are formed by a cytochrome p450-mediated process, important for alpha and gamma-tocopherol excretion. SUMMARY: Insights into the regulation of vitamin E transport and metabolism on the cellular level have made enormous advances, showing the complex interplay of influx, trafficking, efflux and metabolism of this crucial antioxidant.

ATP-Binding Cassette Transporters↗