Analysis of chromosome aberrations and sister chromatid exchanges in peripheral blood lymphocytes of newborns after vitamin K prophylaxis at birth

Vitamin K Deficiency Bleeding: An Ounce of Prevention

Vitamin K is a fat-soluble vitamin essential for the formation of factors in the clotting cascade. Newborns are born with insufficient levels of vitamin K, resulting in high risk for vitamin K deficiency bleeding (VKDB). Vitamin K deficiency bleeding can occur in the first week of life ("classic" VKDB) and also between 2 weeks and 3 months of age ("late" VKDB). Vitamin K deficiency bleeding can present as bleeding in the skin or gastrointestinal tract, with as many as half of affected neonates experiencing intracranial bleeding. A single intramuscular injection of vitamin K effectively prevents both classic and late VKDB. Although intramuscular vitamin K is safe and effective, VKDB has reemerged because of decreased utilization. Parents refuse intramuscular vitamin K for a variety of reasons, including a disproven association with childhood cancer, the desire to avoid exposure to additives, and valid concerns about early neonatal pain. Many parents request oral vitamin K, an inferior alternative strategy that requires multiple doses utilizing products not designed for neonatal oral administration. In this setting, health care professionals must understand the epidemiology of VKDB and compassionately counsel parents to assuage concerns. Delivery of intramuscular vitamin K to all newborns remains a public health imperative, benefitting thousands of infants annually.

Cytoprotective and genotoxic effects of vitamins K1 and B1 on irinotecan in vitro

Cultured human lymphocytes were treated with vitamins K₁ and B₁, potential anticancer agents, either alone or in combination with irinotecan, a semisynthetic analogue of camptothecin. The frequency of sister chromatid exchanges (SCEs) was measured as an indicator of genotoxicity and the proliferation rate index (PRI) and mitotic index (MI) was measured as indicators of cytostatic effect. Vitamin K₁ alone did not induce SCEs at the concentrations tested and combined with irinotecan does not increase SCE rates induced by irinotecan alone. Vitamin B₁ significantly increased SCEs and, in combination with irinotecan, increased rates further (p < 0.05). Vitamin K₁ decreased PRI and MI in combination with irinotecan, there were further increases in MI. At a low concentration, vitamin B₁ reduced the levels of SCE and increased PRI induced by irinotecan. The use of these vitamins in combination with antitumor agents might reduce clinical side effects of the antineoplastics.

Vitamin K status of premature infants: implications for current recommendations

OBJECTIVE

Newborn infants are vitamin K deficient. Vitamin K status in full-term infants after intramuscular vitamin K supplementation at birth has been described. Similar information in growing premature infants has not been reported. The objective of this study was to assess vitamin K status in premature infants by measuring plasma vitamin K and plasma protein-induced in vitamin K absence (PIVKA II) from birth until 40 weeks' postconceptional age.

METHODS

Premature infants (</=36 weeks' gestation) were divided at birth into groups by gestational age (group 1, </=28 weeks; group 2, 29-32 weeks; group 3, 33-36 weeks). Supplemental vitamin K (1 mg intramuscularly) was administered at birth followed by 60 microg/day (weight <1000 g) or 130 microg/day (weight >/=1000 g) via total parenteral nutrition. After hyperalimentation, most received vitamin K-fortified enteral feedings with the remainder receiving unfortified breast milk. Blood was obtained for PIVKA II in cord blood and for PIVKA II and vitamin K at 2 weeks and 6 weeks after birth and at 40 weeks' postconception.

RESULTS

Of the 44 infants enrolled, 10 infants in each gestational age group completed the study. The patient characteristics for groups 1, 2, and 3 were as follows: gestational age, 26.3 +/- 1.7, 30.3 +/- 1.3, and 33.9 +/- 1.1 weeks; birth weight, 876 +/- 176, 1365 +/- 186, and 1906 +/- 163 g; and days of hyperalimentation, 28.9 +/- 16, 16.8 +/- 12, and 4.3 +/- 4 days, respectively. At 2 weeks of age, the vitamin K intake and plasma levels were highest in group 1 versus group 3 (intake: 71.2 +/- 39.6 vs 13.4 +/- 16.3 microg/kg/day; plasma levels: 130.7 +/- 125.6 vs 27.2 +/- 24.4 ng/mL). By 40 weeks' postconception, the vitamin K intake and plasma levels were similar in all 3 groups (group 1, 2, and 3: intake, 11.4 +/- 2.5, 15.4 +/- 6.0, and 10.0 +/- 7.0 microg/kg/day; plasma level, 5.4 +/- 3.8, 5.9 +/- 3.9, and 9.3 +/- 8.5 ng/mL). None of the postnatal plasma samples had any detectable PIVKA II.

CONCLUSIONS

Premature infants at 2 weeks of age have high plasma vitamin K levels compared with those at 40 weeks' postconceptional age secondary to the parenteral administration of large amounts of vitamin K. By 40 weeks' postconception, these values are similar to those in term formula-fed infants. Confirming "adequate vitamin K status," PIVKA II was undetectable by 2 weeks of life in all of the premature infants. With the potential for unforeseen consequences of high vitamin K levels, consideration should be given to reducing the amount of parenteral vitamin K supplementation in the first few weeks of life in premature infants.vitamin K, PIVKA II, premature, total parenteral nutrition, enteral nutrition.

Measurement of DNA damage by the comet assay in rat embryos grown in media containing high concentrations of vitamin K(1)

It has been suggested that vitamin K(1) (phylloquinone) can cause genetic damage in rapidly dividing cells and that this should be considered in the risk/benefit analysis of the prophylactic use of vitamin K(1) in the newborn. Usual intramuscular administration of 1mg of vitamin K(1) to the newborn gives peak plasma levels of 1-2 microg/ml (approximately 2-4 microM). To investigate the possible harmful effects of high concentrations of vitamin K(1), rat embryos undergoing rapid cell division in the organogenic period were cultured for 46 hours in rat sera containing either 1, 10 or 100 microg of added vitamin K(1) per ml (2, 22 or 222 microM). At the end of the culture period the embryos were dissociated and the cells examined for evidence of DNA damage using the alkaline version of the comet assay. Control embryos were cultured in sera without added vitamin K(1) and positive controls were control embryos exposed to hydrogen peroxide at the end of the culture period. The results did not show any evidence of DNA damage in the vitamin K(1) exposed embryos. The positive controls showed a significant increase in tail length, moment and inertia. In conclusion, under the experimental conditions used, high concentrations of vitamin K(1) did not induce primary DNA damage in cells from rat embryos grown in vitro.

Vitamin K status of lactating mothers and their infants

Vitamin K deficiency remains a world-wide problem in the newborn. Vitamin K traverses the placenta from mother to infant very poorly and is present only in very low concentrations in human milk. Thus, it is not surprising that the newborn infant has undetectable vitamin K serum levels with abnormal amounts of the coagulation proteins and undercarboxylated prothrombin. Hemorrhagic disease of the newborn, secondary to vitamin K deficiency, remains largely a disease of breastfed infants. Lactating mothers easily achieve the recommended dietary allowance for vitamin K (1 microg kg(-1) d(-1)) and the breast milk concentration is readily increased by increasing maternal vitamin K intake. Breastfed infants do not receive the recommended vitamin K intake via human milk. To prevent vitamin K deficiency in the newborn, intramuscular or oral vitamin K prophylaxis is necessary.

Effects of beta-carotene, retinal, riboflavin, alpha-tocopherol and vitamins C and K1 on sister-chromatid exchanges induced by 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2) and cyclophosphamide in human lymphocyte cultures

The vitamins and related compounds cited in the title were investigated for their abilities to modulate sister-chromatid exchanges (SCEs) induced by Trp-P-2 or cyclophosphamide (CP) in human peripheral lymphocyte cultures in the presence of an exogenous metabolizing system from rat liver. When inducer and test substances were given simultaneously, beta-carotene, retinal and alpha-tocopherol caused a dose-dependent decrease of SCE frequencies induced by Trp-P-2 and CP. Vitamin K1, however, brought about an identical effect with Trp-P-2 only, while with CP an initial decrease of SCEs was followed by a statistically significant re-increase at higher concentrations. Vitamin C was ineffective against Trp-P-2, but caused an overall increase of SCEs induced by CP. When blood cultures were preincubated with vitamins before the addition of CP or Trp-P-2, basically identical effects were observed with beta-carotene, retinal, alpha-tocopherol, vitamin K1 and vitamin C. Riboflavin decreased SCEs induced by Trp-P-2 in all treatment schedules, although statistically confirmed minima were observed in the dose-response curves, except in post-treatment experiments. On the other hand, riboflavin only reduced SCEs induced by CP when it was preincubated with lymphocytes. When vitamins were applied in a post-treatment schedule after removal of Trp-P-2 or CP, again, basically identical results against both genotoxins were observed with beta-carotene, retinal and alpha-tocopherol with vitamin K1, however, only with respect to Trp-P-2, and with vitamin C only with respect to CP. In the post-treatment schedule, vitamin K1 caused a decrease of SCE frequencies induced by CP, and vitamin C a decrease of SCEs induced by Trp-P-2.

Effect of a reduced vitamin K supplementation on prothrombin time in prematures and high-risk neonates

Recommendations for vitamin K supplementation were recently changed to 3 x 1 mg orally in healthy term neonates and 0.2 mg parenterally in prematures and high-risk neonates. Prothrombin times (PT) at reduced vitamin K doses (120 patients, 170 samples) during the first 6 weeks of life were below 40% in 6 patients only; all low PTs were unrelated to vitamin K. In the remaining patients, median PT was 100%; 79% of patients had values above 70%. PT was related to birthweight, gestational age and age. There was no decrease over the observation period. Following reduced oral and parenteral vitamin K regimens PTs were well within published reference values for neonates given larger amounts of vitamin K.

Childhood cancer, intramuscular vitamin K, and pethidine given during labour

OBJECTIVE

To assess unexpected associations between childhood cancer and pethidine given in labour and the neonatal administration of vitamin K that had emerged in a study performed in the 1970 national birth cohort.

DESIGN AND SETTING

195 children with cancer diagnosed in 1971-March 1991 and born in the two major Bristol maternity hospitals in 1965-87 were compared with 558 controls identified from the delivery books for the use of pethidine during labour and administration of vitamin K.

MAIN OUTCOME MEASURES

Odds ratios for cancer in the presence of administration of pethidine or of intramuscular vitamin K. Both logistic regression and Mantel-Haenszel techniques were used for statistical analyses.

RESULTS

Children of mothers given pethidine in labour were not at increased risk of cancer (odds ratio 1.05, 95% confidence interval 0.7 to 1.5) after allowing for year and hospital of delivery, but there was a significant association (p = 0.002) with intramuscular vitamin K (odds ratio 1.97, 95% confidence interval 1.3 to 3.0) when compared with oral vitamin K or no vitamin K. There was no significantly increased risk for children who had been given oral vitamin K when compared with no vitamin K (odds ratio 1.15, 95% confidence interval 0.5 to 2.7). These results could not be accounted for by other factors associated with administration of intramuscular vitamin K, such as type of delivery or admission to a special care baby unit.

CONCLUSIONS

The only two studies so far to have examined the relation between childhood cancer and intramuscular vitamin K have shown similar results, and the relation is biologically plausible. The prophylactic benefits against haemorrhagic disease are unlikely to exceed the potential adverse effects from intramuscular vitamin K. Since oral vitamin K has major benefits but no obvious adverse effects this could be the prophylaxis of choice.