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Biomedical subjects

A Zipursky

Publications and source records attributed to A Zipursky.

At least 55 records · Page 3Linked to original sources
PubMed1989

Nutritional vitamin B12 deficiency in infancy: three case reports and a review of the literature.

Three cases of vitamin B12 deficiency that occurred during infancy are presented. These cases appeared to be the result of pre-existing maternal deficiency. All three infants demonstrated evidence of neurodevelopmental delay at presentation, and one had sustained loss of milestones and developed involuntary motor movements. Prior to the initiation of therapy, all three infants were anemic: one was thrombocytopenic and one pancytopenic. In all three cases the hematologic and neurologic abnormalities were corrected with vitamin B12 therapy. The literature is reviewed and discussed with respect to the mechanism of the infants' vitamin B12 deficiency and neurodevelopmental manifestations.

Anemia, Megaloblastic↗
PubMed1988

Bleeding diathesis in Noonan syndrome: a common association.

The Noonan syndrome (NS) is a multiple congenital anomalies (MCA) syndrome with well-known manifestations. Excessive bleeding has been described occasionally. We report on 19 patients with NS and a bleeding diathesis. Several different defects are identified in the coagulation and platelet systems occurring singly or in combination. Clinical expression is variable. It is concluded that bleeding diatheses occur in NS at a much higher frequency than previously suspected. Consideration is given to possible relationship to underlying metabolic defects which could explain the diverse nature of the bleeding diatheses and also play a role in the pathogenesis of NS. The variety of bleeding diatheses may also reflect heterogeneity within NS. NS patients frequently undergo surgery with increased risk of bleeding. Appropriate evaluation and management is discussed. Evaluation of all NS patients and their families for bleeding disorders should provide important information about the frequency and type of bleeding diatheses which occur and perhaps help to clarify the etiology and pathogenesis of NS.

Adolescent↗
PubMed1988

Vitamin C-induced erythrocyte damage in premature infants.

This study was undertaken after the observation in a premature infant of a hemolytic anemia with Heinz bodies that appeared to result from administration of a multivitamin preparation. In vitro incubation of erythrocytes of premature infants with sodium ascorbate (0.1 mg/ml) for 3 hours significantly raised the number of Heinz body-containing cells from 17.6 +/- 5.7% to 27.2 +/- 8.2% (mean +/- SE). Erythrocytes of term infants and those of adults developed Heinz bodies after exposure to higher sodium ascorbate concentrations (1.0 mg/ml). Erythrocytes of adult and newborn guinea pigs were similarly affected by sodium ascorbate. Daily intraperitoneal injections of 500 mg of sodium ascorbate, given for 7 days to four adult guinea pigs, caused significant Heinz body formation. These studies indicate that the erythrocytes of premature infants are uniquely sensitive to the development of Heinz bodies after exposure to sodium ascorbate. The levels required to produce Heinz bodies in vitro are in the range of those found in vivo after routine administration of vitamin C to premature infants. The significance of these observations in the development of hyperbilirubinemia in premature infants and in the safety of vitamin C remains to be determined.

Adult↗
PubMed1988

Physician compliance and relapse rates of acute lymphoblastic leukemia in children.

We studied the prescription patterns of maintenance therapy for children with acute lymphoblastic leukemia and their association with duration of complete remission. Both 6-mercaptopurine and methotrexate (MTX) were prescribed in doses significantly lower than those recommended (75 mg/m2 daily 6-mercaptopurine; 20 mg/m2 weekly MTX) during maintenance therapy. Of 212 evaluated patients, patients who had relapses (n = 101) received significantly less MTX compared with patients who did not have relapses (n = 111) during the first 2 years of maintenance therapy. In the group of standard-risk patients who received the same induction therapy (n = 92), 11 of 17 who received less than 50% of the recommended MTX dose (64%) and 28 of 75 who received greater than 50% of the dose (37%) had relapses (P less than 0.05). The two groups had comparable periods of interruption of MTX therapy. Further analysis revealed that the lower maintenance dose stemmed from a continuous low prescribed dose and not from more frequent interruption of therapy in relapse. Physicians' inability or failure to adhere to the recommended protocol was associated with a higher relapse rate of acute lymphoblastic leukemia. Improved physicians' compliance may improve the prognosis of the disease.

Administration, Oral↗
PubMed1988

Severe thrombocytopenia in sickle cell crisis.

Thrombocytopenia is unusual in sickle cell disease. We present the case of a child with homozygous sickle cell disease who experienced life-threatening thrombocytopenia during a prolonged and disabling vasoocclusive episode. Irreversibly sickled cells were conspicuously absent from the peripheral blood at presentation and during the subsequent protracted illness. These observations illustrate the pathophysiology of the intravascular events during vasoocclusive crisis and provide indirect evidence for the consumption of both platelets and irreversibly sickled cells at sites of infarction.

Anemia, Sickle Cell↗
PubMed1987

Reduction of platelet counts induced by mechanical ventilation in newborn infants.

The association between platelet counts and mechanical ventilation was assessed in 61 newborn infants with respiratory distress syndrome, 10 infants with congenital diaphragmatic hernia, and 10 infants with tracheoesophageal fistula. A significant decrease in platelet counts was observed during mechanical ventilation: (mean +/- SD) reduction of 39% +/- 5%, 42% +/- 5.6%, and 11.9% +/- 5.4% in the three groups, respectively, independent of other causes. In the group with congenital diaphragmatic hernia, there was a significant correlation between mean airway pressure and the reduction in platelet counts. In a subsequent series of experiments, platelet counts were recorded before and during ventilation in rabbits. A significant mean decrease of 37.3% in platelet counts was associated with ventilation with either air or pure oxygen. Results of these studies indicate that mechanical ventilation itself may cause a major decrease in platelet count in newborn infants.

Animals↗
PubMed1987

Maternal erythrocytes in the fetal circulation. The immunocytochemical identification of minor populations of erythrocytes.

Maternal erythrocytes (Rh+) have been identified in the fetal circulation of Rh- infants by the use of a simple immunocytochemical staining technic. Placental or capillary blood from an Rh- infant of an Rh+ mother was incubated in sequence with Rh immunoglobulin, rabbit antihuman IgG, and finally goat antirabbit IgG-alkaline phosphatase conjugate. Maternal cells were found in 14% (11 of 80) of placental vein samples and 10% (2 of 20) of capillary samples. The volume of maternal blood present in the fetal circulation was calculated to be 0.06-2.3 mL with the use of placental vein samples and 0.6-1.25 mL with the use of capillary blood.

Capillaries↗
PubMed1987

Megakaryoblastic leukemia and Down's syndrome: a review.

Megakaryoblastic leukemia and transient leukemia in Down's syndrome have been reviewed using case reports from the literature and our own experience at the Hospital for Sick Children. The following conclusions have been reached: (1) approximately 20% of leukemia (excluding transient leukemia) in Down's syndrome is acute megakaryoblastic leukemia; (2) approximately 20% of all leukemia in Down's syndrome is transient leukemia; (3) transient leukemia in Down's syndrome is acute megakaryoblastic leukemia; (4) recurrence of acute megakaryoblastic leukemia occurs in 20% of the cases of transient leukemia; and (5) the incidence of acute megakaryoblastic leukemia in Down's syndrome is estimated to be 400 times that in normal children. These observations suggest that a specific form of leukemia, namely acute megakaryoblastic leukemia, has a remarkable association with Down's syndrome.

Age Factors↗
PubMed1987

Oral vitamin E supplementation for the prevention of anemia in premature infants: a controlled trial.

Serum vitamin E levels are reduced in newborn infants. It has been reported that this deficiency is responsible, in part, for the development of anemia in premature infants during the first 6 weeks of life. The efficacy of vitamin E supplementation for the prevention of anemia in premature infants has been studied in a randomized, controlled, and blinded trial. Premature infants whose birth weights were less than 1,500 g were given, by gavage, 25 IU of dl-alpha-tocopherol or a similar volume of the drug vehicle. Treatment was continued for the first 6 weeks of life. A total of 178 infants were studied. Vitamin E levels were significantly higher in a supplemented group by day 3 and for the remainder of the 6-week period. At 6 weeks of age, there was no significant difference between the supplemented and unsupplemented groups in hemoglobin concentration, reticulocyte and platelet counts, or erythrocyte morphology. It is concluded that there is no evidence to support a policy of administering vitamin E to premature infants to prevent the anemia of prematurity.

Anemia, Neonatal↗
PubMed1986

Low antithrombin III in neonatal shock: DIC or non-specific protein depletion?

Low antithrombin III (AT III) levels in shock are usually ascribed to disseminated intravascular coagulation (DIC). However, decreased activities of clotting factors and their inhibitors could reflect a generalised fall in plasma proteins rather than DIC. AT III and albumin were compared in 48 asphyxiated and non-asphyxiated newborn rabbits (pH 6.70-7.30). Both AT III and albumin were markedly decreased in the sickest animals and there was a direct linear relationship between the two proteins (P less than 0.001). Similar results were obtained in ten newborn infants suffering from shock and haemorrhagic diathesis. In all cases AT III and albumin were decreased below the normal range and significantly correlated (P less than 0.01). Our findings suggest that AT III is not a useful diagnostic marker of DIC. Further, a similar fall of clottable and non-clottable proteins in shock questions the general assumption that the ensuing coagulopathy is due to intravascular coagulation.

Animals↗
PubMed1986

Pharmacokinetic determinants of 6-mercaptopurine myelotoxicity and therapeutic failure in children with acute lymphoblastic leukemia.

The pharmacokinetics of oral 6-mercaptopurine (6MP) was assessed in 20 children with acute lymphoblastic leukemia during maintenance therapy. The AUC was between 0 and 6 X 10 ng X min/ml, and AUC normalized to 1 mg/m2 of 6MP was between 0 and 815 ng X min/ml. Good correlation existed between peak concentrations and AUC (r = 0.866; P less than 0.001). In more than half of the cases there was evidence of prolonged elimination t1/2 or rebound of a serum concentration during the elimination phase corresponding to either an additional compartment or enterohepatic circulation of 6MP. One child did not achieve detectable concentrations on 2 different study days and was switched to a different protocol. The two children who had severe myelotoxicity achieved the largest AUC values per milligram per square meter of 6MP. Our results indicate that pharmacokinetic variability may contribute to either severe myelotoxicity or therapeutic failures. This suggests that monitoring of this drug in children with acute lymphoblastic leukemia may be helpful.

Administration, Oral↗
PubMed1986

The effect of abdominal radiation on spleen function: a study in children with Wilms' tumor.

Reports of splenic dysfunction in patients with Hodgkin's disease who received radiation therapy to the spleen raise questions concerning impairment of splenic function and the long-term risk of bacterial sepsis in children who receive abdominal radiation for other diseases. Splenic function was studied in 20 children with Wilms' tumor using a quantitative assessment of vacuolated ("pitted") red cells as a measure of reticuloendothelial function. Fourteen children had received abdominal radiation to a field involving the spleen at a median dose of 2000 rads. Their pitted red cells counts were no different from those of 6 children who received therapy without radiation to the spleen or to those of a group of normal children and adults. We conclude that there is no demonstrable long-term impairment of spleen function with radiation doses at or below 2200 rads.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1985

Analysis of 6-mercaptopurine in serum or plasma using high performance liquid chromatography.

The analysis of 6-mercaptopurine (6-MP) by a rapid, sensitive, and specific high performance liquid chromatographic assay is described. This method does not require any derivatization and allows for direct quantitation of the drug. Only 200 microliters of serum or plasma is needed, and concentrations as low as 10 ng/ml can be reliably quantitated. Analytical recoveries of 83% for 6-MP and 71% for the internal standard, 6-thioguanine, are obtained. Between-day precision studies at three plasma concentrations of 6-MP produce a mean coefficient of variation of 7.2%. This assay will be clinically useful for pharmacokinetic studies of 6-MP in patients in remission of acute lymphoblastic leukemia.

Child↗