Esther D. Israels

1-Desamino-8-D-arginine Vasopressin (Desmopressin) Decreases Operative Blood Loss in Patients Having Harrington Rod Spinal Fusion Surgery: A Randomized, Double-Blinded, Controlled Trial

To evaluate the effect of 1-desamino-8-D-arginine vasopressin (desmopressin) on blood loss in surgery, we conducted a randomized, double-blind trial of the drug in 35 patients with normal hemostatic function who were having spinal fusion with Harrington rod instrumentation. Seventeen patients were designated to receive 10 micrograms/m2 of desmopressin, and 18, to receive a placebo. Preoperative testing showed that desmopressin increased factor VIII coagulant activity, von Willebrand antigen concentrations, glass bead platelet retention, and prothrombin consumption and decreased the partial thromboplastin and bleeding times (p less than or equal to 0.0003). During surgery, desmopressin reduced blood loss by 32.5% (547 mL; 95% confidence interval [CI], 19 to 1075; p = 0.015) and reduced the need for concentrated erythrocyte transfusions by 25.6% (0.86 units; 95% CI, 0.08 to 1.65; p = 0.022). After surgery, desmopressin reduced the duration of treatment with analgesic agents by 13.1% (34.0 hours; 95% CI, -5.2 to 72.7; p = 0.105), presumably by decreasing bleeding in the surgical wound. When adjusted for the origin of the scoliosis by two-way analysis of variance, this effect was even more evident (p = 0.014). Multiple regression analysis showed that the best three predictors of blood loss in surgery and transfusion requirements were the bleeding time, glass bead platelet retention, and the use of desmopressin.

Development of antibodies to bovine and human factor V in two children after exposure to topical bovine thrombin.

Purpose Acquired inhibitors to coagulation factors are rare in pediatric patients. Exposure to topical bovine thrombin is a risk factor for the development of inhibitors in adult cardiac surgery patients. We report two pediatric patients who developed inhibitors to bovine and human factor V after exposure to fibrin glue containing bovine thrombin. Patients and Methods The two patients, ages 31/2 years and 10 months, were studied after cardiac surgery. One patient had clinical bleeding. Coagulation factor assays and inhibitor studies were performed. Results The presence of a circulating inhibitor to bovine factor V was observed in both patients and to human factor V in one patient. The inhibition of bovine factor V interfered with standard assays for factor VIII activity using a commercial substrate fortified with bovine factor V resulting in spurious factor VIII deficiency. In one patient, an inhibitor of bovine thrombin was also identified. The inhibition of human factor V activity in one patient may have contributed to clinical bleeding. Conclusions Pediatric patients exposed to topical bovine thrombin, particularly in the setting of cardiac surgery, are at risk for the development of antibodies to bovine thrombin and factor V. This may also result in apparent but spurious depletion of other coagulation factors. These antibodies may cross-react with human coagulation factors, particularly factor V, resulting in clinical bleeding.

Inherited platelet-storage pool deficiency associated with a high incidence of acute myeloid leukaemia

Summary A family with an inherited bleeding disorder extending over four generations, and multiple cases of myeloblastic and myelomonoblastic leukaemia was studied. Ten members of the family had, by history, a haemorrhagic diathesis. There were three documented cases of myeloblastic leukaemia, two documented cases of myelomonoblastic leukaemia and two more cases of leukaemia by history. In four of the cases the bleeding diathesis clearly antedated the leukaemia, in two by many years. The bleeding disorder is characterized by a long bleeding time, abnormal platelet aggregation, low platelet ADP and decreased numbers of platelet dense bodies consistent with a dense granule storage pool deficiency. The number of dense granules was decreased by immunofluorescence employing quinacrine or using an antibody to the dense granule membrane protein, granulophysin, confirming an absolute decrease in dense granule numbers rather than the presence of empty granule sacs. This congenital storage pool deficiency is associated with a high incidence of acute myeloid leukaemia in this family.

Novel vitamin K-dependent pathways regulating cell survival.

Historically, the vitamin K1-dependent proteins have been associated primarily with blood coagulation and secondarily with bone formation. Recent identification of K1-dependent proteins as specific ligands for the receptor tyrosine kinases (RTKs) that can stimulate cell replication and transformation and participate in cell survival highlighted a previously unrecognized and potentially important role for vitamin K1 in cell signaling. Growing evidence suggests that most normal and tumor cells possess an active K1-dependent γ-carboxylation mechanism necessary for the production of γ-carboxyglutamic acid (Gla)-containing proteins. Gla residues in proteins facilitate calcium-dependent protein/phospholipid interaction. Recent studies demonstrating the potentially positive effects of a vitamin K-dependent receptor:ligand system on cell growth and survival in general and the effects of the overexpression of these RTKs on malignant cell survival provide a new perspective on the role of vitamin K1, its dependent protein ligands, and their receptors. These cumulative observations also provide an explanation for the rigidly controlled K1 levels in the mammalian fetus and the minimal hepatic stores in the adult.

Vitamin K as a regulator of benzo(a)pyrene metabolism, mutagenesis, and carcinogenesis. Studies with rat microsomes and tumorigenesis in mice.

Vitamin K3 inhibits the conversion of benzo(a)pyrene to its more polar metabolites in an in vitro rat liver microsomal system. Vitamin K3 also inhibits benzo(a)pyrene metabolism in rat liver fragments and reduces its mutagenicity in the Ames test. Higher concentrations of vitamin K3 are required to comparably reduce benzo(a)pyrene metabolism when the microsomal system has been induced with 3-methylcholanthrene. High pressure liquid chromatography analysis of the products of benzo(a)pyrene metabolism shows a uniform reduction of all the metabolic products. When tumors were induced in ICR/Ha female mice by the intraperitoneal injection of benzo(a)pyrene, those mice given vitamin K3 before or both before and after benzo(a)pyrene had a slower rate of tumor appearance and tumor death rate as compared with those receiving benzo(a)pyrene alone. However, vitamin K1 increased the rate of tumor death while vitamin K deprivation and warfarin decreased the rate of tumor appearance and death in benzo(a)pyrene-injected mice. These studies indicate that vitamin K3 is an inhibitor of aryl hydrocarbon hydroxylase and reduces the carcinogenic and mutagenic metabolites in vitro, and inhibits benzo(a)pyrene tumorigenesis in vivo. That vitamin K1 enhances the benzo(a)pyrene effect while warfarin and vitamin K deficiency inhibit benzo(a)pyrene tumorigenesis indicates that vitamin K1, vitamin K deprivation, or possibly blockade of its metabolic cycle also modulates benzo(a)pyrene metabolism in vivo but by a mechanism or at a site different from the vitamin K3 effect. The vitamin K series should be considered as capable of serving a regulatory function in the metabolism of benzo(a)pyrene and possibly other compounds metabolized through the mixed function oxidase system.

Vitamin K1 Increases Sister Chromatid Exchange in Vitro in Human Leukocytes and in Vivo in Fetal Sheep Cells: A Possible Role for “Vitamin K Deficiency” in the Fetus

ABSTRACT. The levels of the vitamin K-dependent clotting factors are markedly lower in the human fetus and newborn than in older infants and adults. Direct measurement of vitamin K1 in cord plasma records low or undetectable levels. This phenomenon, although the norm, is referred to as vitamin K deficiency and is a significant risk factor for hemorrhage in the fetus and newborn. Sister chromatid exchange (SCE), which may be used as an index of mutagenic activity, was assayed in cultured leukocytes of placental and adult blood following phytohemagglutinin stimulation. The mean number of SCEs per metaphase in human placental blood was 3.32 ± SE 0.219 as compared with levels of 5.13 ± SE 0.273 in young adults (p < 0.01), and in the presence of added vitamin K1 at a concentration of 1 × 10−6 M the SCE increased significantly in both adult and placental cells. In vitro SCE dose response curves to K1 in the blood of fetal and maternal sheep were obtained. When five fetal sheep were given 1 mg of K1 by catheter into the femoral vein the SCE increased from 3.94 ± SE 0.15 preinjection to 5.38 ± SE 0.23 at 24 h postinjection (p < 0.01). In the pretreatment fetal sheep, serum vitamin K1 was below detectable levels in all seven animals in which it was assayed and reached levels as high as 0.3 × 10−6 M 1 h post-K1 injection. The low level of K1 in the fetus may in fact confer some biological advantage by reducing the risk of mutagenic events during a period of rapid cell proliferation.

Synergistic Shortening of the Bleeding Time by Desmopressin and Ethamsylate in Patients with Various Constitutional Bleeding Disorders

Desmopressin and ethamsylate were evaluated for possible synergistic effects on the bleeding time. The drugs were administered individually and together to 12 patients with markedly prolonged bleeding times known to be relatively or absolutely unresponsive to desmopressin alone. The bleeding disorders studied included Glanzmanns thrombasthenia (one), other disorders of platelet function (four), pseudo-von Willebrand disease (one), and von Willebrand disease type I (three), type II (two), and type III (one). Desmopressin alone shortened the bleeding time from 23.9 +/- 1.5 to 19.5 +/- 2.3 min (p = 0.03). Ethamsylate alone was without effect. Desmopressin and ethamsylate together shortened the bleeding time to 11.2 +/- 1.4 min (p less than 0.01 compared to baseline, p = 0.02 compared to desmopressin alone). The combination was ineffective in three patients, with Glanzmanns thrombasthenia (one), and von Willebrand disease type I (one) and type III (one). Toxic effects of the drugs were not observed. Five patients received desmopressin and ethamsylate prior to dental work with mandibular block (one), heart surgery requiring cardiopulmonary bypass (two), and adenotonsillectomy surgery (two). Normal hemostasis was achieved in each case. A synergistic shortening of the bleeding time was observed with the combination of desmopressin and ethamsylate in a wide range of bleeding disorders.

Vitamin K1 as a modulator of benzo(a)pyrene metabolism as measured by in vitro metabolite formation and in vivo DNA-adduct formation

Vitamin K1 (2-methyl-3-phytyl-1,4-napthoquinone) increases the microsomal metabolism of benzo(a)pyrene in rat liver microsomes in vitro. The increase is most marked in the 9,10 diol, 4,5 diol and 3-OH metabolites. The effect is seen at an in vitro concentration of 25 microM and disappears at higher concentrations of K1. The production of BP metabolite-DNA adducts in liver in vivo in ICR/Ha mice is reduced in dietary induced vitamin K deficient mice and this effect is reversed by vitamin K1. These findings indicate a role for vitamin K1 in the regulation of the microsomal mixed function oxidase system and suggest a reason for the low intracellular content and minimal body stores of this vitamin.

Studies in patients with bleeding disorders show that platelet-vessel interaction is important for thromboxane formation in bleeding time wounds

The production of thomboxane B2, the primary metabolite of thromboxane A2, and 6-keto prostaglandin F1 alpha, the primary metabolite of prostacyclin, were measured in response to a standardized vascular injury, the bleeding time, in patients with von Willebrands disease and in patients with platelet function defects. Compared to controls, thromboxane B2 levels in bleeding time blood were significantly lower in subjects with von Willebrands disease. In patients with platelet function defects associated with a deficient response to thromboxane A2, thromboxane B2 production in bleeding time blood was similar to controls. In subjects with other platelet function defects, thromboxane production was significantly lower than normal. 6-keto PGF1 alpha production in bleeding time blood was not significantly different in patients compared to controls. The results suggest that bleeding time thromboxane production is influenced by the extent of platelet-vessel interaction.

DDAVP (1-DESAMINO-8-D-ARGININE VASOPRESSIN) DECREASES OPERATIVE BLOOD LOSS IN PATIENTS UNDERGOING HARRINGTON ROD SPINAL FUSION SURGERY

To evaluate the effect of l-desamino-8-D-arginine vasopressin (DDAVP) on surgical blood loss, 35 hemostatically-normal subjects received 10 μg/M2 DDAVP or placebo by randomized double-blind assignment prior to Harrington rod spinal fusion. On preoperative testing, DDAVP increased factor VIII coagulant activity, von Willebrand antigen, platelet adhesiveness and prothrombin consumption and decreased the partial thromboplastin time and the bleeding time (p<.0003). At surgery, the drug reduced blood loss by 32.3% (1681 ± 901 ml in the placebo group vs. 1134 ± 593 ml in the treated group, p=.03) and similarly, reduced the requirement for concentrated red cell transfusions by 26.5% (3.36 ± 1.64 units in the placebo group vs. 2.50 ± 0.97 units in the treated group, p=.04). Post-operatively, the drug reduced the duration of analgesia from 201.5 ± 83.0 hours in the placebo group to 149.0 ± 64.0 hours in the treated group (p=.01), presumably by decreasing bleeding into the surgical wound. By multivariate regression analysis, the best three predictors of surgical blood loss (p=.024) and transfusion requirements (p=.008) were the bleeding time, platelet adhesiveness and the use of DDAVP. In conclusion, DDAVP shortens the bleeding time and decreases operative blood loss in hemostatically normal subjects.