PubMed Health⌕ Search

Biomedical subjects

T Valaes

Publications and source records attributed to T Valaes.

At least 19 recordsLinked to original sources
PubMed2001

A single dose of Sn-mesoporphyrin prevents development of severe hyperbilirubinemia in glucose-6-phosphate dehydrogenase-deficient newborns.

OBJECTIVES: Severe neonatal jaundice is a common clinical manifestation of glucose-6-phosphate dehydrogenase (G-6-PD) deficiency and the most difficult to manage; kernicterus is not an uncommon outcome. We assessed in healthy, direct Coombs test-negative Greek newborns of >/=38 weeks' gestational age 1) the current burden of G-6-PD deficiency-associated severe jaundice, and 2) the efficacy of preventive use of Sn-mesoporphyrin (SnMP), a potent inhibitor of heme oxygenase activity and thus of bilirubin production, in ameliorating jaundice in G-6-PD-deficient neonates. METHODS: The studies were conducted at Metera Maternity Hospital in Athens, Greece. Enrolled newborns had the plasma bilirubin concentration (PBC) determined in cord blood and daily thereafter until a declining level was obtained and the case was closed. Intervention with phototherapy was dictated at exact, age-specific PBC levels. In our initial study, we enrolled consecutive mature healthy G-6-PD-deficient newborns as well as a threefold excess of G-6-PD-normal neonates born at approximately the same time (control group). For the SnMP trial, G-6-PD-deficient neonates were administered SnMP as a single intramuscular dose of 6 micromol/kg birth weight within 24 +/- 12 hours of age. RESULTS: SnMP was administered at 26.7 +/- 6.1 hours of age to 172 G-6-PD-deficient newborns (group A); 168 G-6-PD-normal (group B) and 58 G-6-PD-deficient (group C) newborns who were enrolled earlier provided the comparison groups. Except for the expected excess of males in the G-6-PD-deficient groups (A and C), there were no differences in the demographic characteristics among the 3 groups. The incremental changes in PBC from cord blood to 24 hours of age also were similar (group A: 4.13 +/- 1.32 mg/dL; group B: 4.05 +/- 1.34 mg/dL; group C: 4.39 +/- 1.07 mg/dL), but there were significant differences in the next period, 24 to 48 hours of age (group A: 0.63 +/- 1.44 mg/dL; group B: 1.69 +/- 1.5 mg/dL; group C: 2.45 +/- 1.72 mg/dL). Peak PBC was significantly different (group A: 7.81 +/- 3.04 mg/dL; group B: 8.68 +/- 3.1 mg/dL; group C: 11.24 +/- 3.76 mg/dL) as was the age at which peak PBC was recorded (group A: 56 +/- 29 hours of age; group B: 69 +/- 26 hours of age; group C: 83 +/- 29 hours of age). These differences in favor of group A were observed despite the fact that phototherapy was used in 15% of the newborns in group B and 31% of those in group C, whereas none of those treated with SnMP required phototherapy. Finally, in one female, who was heterozygous for G-6-PD deficiency, in group C phototherapy failed and 2 exchange transfusions were performed. CONCLUSIONS: In comparison with normal neonates, G-6-PD-deficient neonates experienced a twofold increase in the prevalence of significant hyperbilirubinemia requiring phototherapy. A single dose of SnMP administered in the 1st day of life to the G-6-PD-deficient newborns shifted the peak PBC distribution to the left (lower values) even in relation to normal neonates and entirely eliminated the need for phototherapy. Interdiction of bilirubin production by use of a heme oxygenase inhibitor such as SnMP represents a simple and highly effective means for the preventive management of jaundice in G-6-PD-deficient newborns.

Case-Control Studies↗
PubMed1998

Control of hyperbilirubinemia in glucose-6-phosphate dehydrogenase-deficient newborns using an inhibitor of bilirubin production, Sn-mesoporphyrin.

BACKGROUND: Hyperbilirubinemia in new-borns with glucose-6-phosphate dehydrogenase (G6PD) deficiency is a serious clinical problem because of the severity and unpredictability of its course. An innovative approach to this problem is suggested by previous experience with Sn-mesoporphyrin (SnMP), a potent inhibitor of bilirubin production, in moderating neonatal hyperbilirubinemia caused by ABO incompatibility, immaturity, and unspecified mechanisms. OBJECTIVE: To compare the effectiveness of the preventive and therapeutic uses of SnMP in ameliorating the course of bilirubinemia of G6PD-deficient neonates. METHODS: Neonates born at the Metera Maternity Hospital, Athens, Greece, and found to be G6PD-deficient by cord blood testing were stratified by sex and gestational age (210-265 days and >265 days) and randomized in pairs to receive SnMP (6 micromol/kg birth weight, intramuscularly) either on the first day of life (preventive use) or if and when the plasma bilirubin concentration (PBC) level reached an age-specific threshold level for intervention (therapeutic use). In the case of failure of SnMP to control the rise of PBC levels, the protocol defined precisely the threshold PBC levels for switchover to phototherapy (PT) and, if necessary, exchange transfusion. PBC was measured daily until a declining value was obtained and the case was closed. RESULTS: A total of 86 G6PD-deficient neonates were randomized: 42 in the preventive arm and 44 in the therapeutic arm. Of the latter, 20 (45%) reached PBC levels requiring therapeutic intervention and thus received SnMP. Regardless of the trial arm, none of the 86 neonates required PT, whereas in a previous study in the same population, 33% of G6PD-deficient neonates required PT. In the intrapair sequential analysis, the favored arm was decided on the criterion of the age at closure of the case being shorter by at least 1 day. After plotting 30 untied pairs in the sequential analysis graph, the preventive use of SnMP proved to be the favored arm, and the trial was stopped. At this point, there were 2 unpaired neonates, 12 tied pairs, 22 pairs in which the preventive use of SnMP was favored and 8 pairs in which the therapeutic use of SnMP was favored. In the group analysis, infants in the preventive group, compared with those in the therapeutic group, had a lower maximum PBC level (8.2 +/- 3.1 and 10.9 +/- 2.8 mg/dL, respectively), which was reached at an earlier age (63.5 +/- 34.8 and 82.2 +/- 24.7 hours, respectively) as well as a lower closing PBC level (7.2 +/- 2.9 and 9.6 +/- 2.5 mg/dL, respectively) and an earlier age at closing (89.1 +/- 35.6 and 110.8 +/- 23.6 hours, respectively). Moreover, a PBC level of >/=8.0 mg/dL, a level at which jaundice is clearly visible, was not reached by 52% of the neonates in the preventive arm and 16% of the neonates in the therapeutic arm. CONCLUSIONS: In G6PD-deficient neonates, a single dose of SnMP administered preventively or therapeutically entirely supplanted the need for PT to control hyperbilirubinemia. The preventive use of SnMP offers practical advantages in populations with a high enough prevalence of G6PD deficiency to justify cord blood screening.

Bilirubin↗
PubMed1996

The impact of phototherapy in the management of neonatal hyperbilirubinemia: comparison of historical cohorts.

To quantitatively assess the impact of phototherapy (PT) in the prevention of kernicterus we calculated the rate of exchange transfusion (ET) in two large historical cohorts of Greek neonates (birthweight > or = 2.5 kg), one before (period I: 1957-61) and one after (period II: 1980-92) the introduction of PT. Overall, the introduction of PT was associated with a reduction of the rate of ET from 0.43% in period I to 0.05% in period II. The reduction was observed in all etiological categories but was more marked in the ABO-incompatible group. With an estimated rate of kernicterus without treatment of 0.085% (excluding rhesus hemolytic disease of the newborn and prematurity) we estimated that 4.2 and 0.36 infants were treated by ET for each spared kernicterus in periods I and II, respectively. Finally, in period II 185 infants were treated with PT or PT and ET for each spared kernicterus.

Cohort Studies↗
PubMed1995

Direct comparison of Sn-mesoporphyrin, an inhibitor of bilirubin production, and phototherapy in controlling hyperbilirubinemia in term and near-term newborns.

BACKGROUND: Sn-mesoporphyrin (SnMP) is a potent inhibitor of bilirubin production. In our previous studies a single dose (6 mumol/kg birth weight) significantly moderated hyperbilirubinemia and reduced phototherapy (PT) time by > 75% when administered within 24 hours of birth to preterm infants. OBJECTIVE: To directly compare the efficacy of SnMP and PT for controlling hyperbilirubinemia in term and near-term infants. METHODS: Two randomized, sequentially analyzed trials (Study I: male term infants; Study II: infants of both sexes and gestational age [GA] 245-265 days) were conducted. SnMP (6 mumol/kg birth weight) or PT (Phillips F20T12/BB lamps) was administered to paired infants according to strict criteria of plasma bilirubin levels and age. Time of enrollment and closure of cases and crossover, if necessary, of SnMP infants to PT or all infants to exchange transfusion were precisely defined in each pair. SnMP or PT was considered superior if the time between enrollment and closure of the case was reduced by > 24 hours over the alternative treatment or if crossover had occurred. RESULTS: None of the 44 SnMP-treated infants required supplemental PT. Of the 22 pairs of term infants enrolled in Study I, SnMP proved superior to PT in 20 and equal in two. Of the 20 pairs of near-term infants enrolled in Study II, SnMP was superior in 12 and PT in two; six were tied. Two SnMP-treated infants were unpaired. The PT-treated infants in Study I required an average of 33 hours of treatment; those in Study II, 48 hours. None of the enrolled infants required exchange transfusion or interruption of breast-feeding. In both studies, times between case enrollment and closure were reduced by > 30 hours in SnMP compared with PT infants; requirements for additional days of medical observation and bilirubin measurements were also significantly less in SnMP infants. CONCLUSION: A single dose of SnMP entirely supplanted the need for PT in jaundiced term and near-term newborns and significantly reduced medical resource use to monitor hyperbilirubinemia.

Female↗
PubMed1994

Severe neonatal jaundice associated with glucose-6-phosphate dehydrogenase deficiency: pathogenesis and global epidemiology.

The association of glucose-6-phosphate dehydrogenase deficiency (G6PD def) with severe neonatal jaundice (NJ) and Kernicterus was described just over 30 years ago in reports from Sardinia (1-4) Singapore (5,6) and Greece (7,8). In this review we will examine the progress made since that time in our understanding of the pathophysiology of severe NJ associated with G6PD def, its global epidemiology, and its role in the balanced polymorphism of the G6PD def gene (Gd). Including this review in the Festschrift to Spyros Doxiadis should highlight his contribution to the field. In Greece the search for a new cause of severe NJ and Kernicterus was triggered by his realization that the recognized at the time, causes of severe NJ were absent in a large proportion of the neonates treated at the "Alexandra" Maternity Hospital in Athens (9).

Animals↗
PubMed1994

Control of jaundice in preterm newborns by an inhibitor of bilirubin production: studies with tin-mesoporphyrin.

BACKGROUND: Studies in vitro, in animal models, and in adult and newborn humans have demonstrated that certain tin(Sn)-porphyrins that competitively inhibit the activity of heme oxygenase, the rate-limiting enzyme in heme catabolism, reduce production of bilirubin and can thereby substantially diminish plasma levels of the bile pigment. OBJECTIVES: To assess the effectiveness of increasing doses of the heme oxygenase inhibitor, Sn-mesoporphyrin (SnMP), in moderating the development of significant hyperbilirubinemia and thus the requirements for phototherapy in preterm newborns. METHODS: In five randomized, blinded, placebo-controlled trials, SnMP in increasing doses from 1 mumol to 6 mumol/kg body weight was administered intramuscularly in the first 24 hours of life in preterm newborns of 210 to 251 days gestational age. "Special blue" lamps (Phillips F20T12/BB) were used for phototherapy in newborns exceeding a predetermined plasma bilirubin concentration, irrespective of study group. RESULTS: A total of 517 newborns were randomized in the five trials carried out sequentially over a 4-year period. SnMP in a dose-related manner significantly ameliorated the course of hyperbilirubinemia in the treated newborns of all gestational ages. With a SnMP dose of 6 mumol/kg body weight, the mean peak incremental plasma bilirubin concentration was reduced by 41% and the phototherapy requirements were decreased by 76% compared to control subjects. Erythema observed in a few SnMP-treated newborns who required phototherapy was mild, transient, and without sequelae. No other untoward effects were observed during hospitalization or at a follow-up at post-term age of 3 and 18 months. CONCLUSIONS: SnMP, by inhibiting the production of bilirubin, substantially moderates the development of hyperbilirubinemia in preterm newborns. This compound and similarly acting enzyme inhibitors merit further clinical study as agents for controlling neonatal hyperbilirubinemia, particularly in neonatal populations for whom other treatment modalities are not available.

Bilirubin↗
PubMed1988

Sn-protoporphyrin use in the management of hyperbilirubinemia in term newborns with direct Coombs-positive ABO incompatibility.

In two separate studies, in which two different treatment regimens of Sn-protoporphyrin were used, a total of 69 control and 53 treated infants were studied to determine whether this potent inhibitor of the enzyme, heme oxygenase, could ameliorate the severity of the hyperbilirubinemia which develops in term babies with direct Coombs-positive ABO incompatibility. The results indicate that Sn-protoporphyrin can, in appropriate doses, moderate the postnatal rate of increase of plasma bilirubin levels and diminish the intensity of hyperbilirubinemia in treated babies. In addition, a decreased use of phototherapy in Sn-protoporphyrin-treated infants was observed. No rebound hyperbilirubinemia was detected during the six- to eight-day period after Sn-protoporphyrin administration. The plasma clearance (t1/2) of Sn-protoporphyrin was much faster in newborns than in adults (approximately 1.6 hours v 3.5 hours, respectively). The incidence of clinical side effects in the 53 Sn-protoporphyrin-treated infants was limited to the development of transient erythema during the use of concurrent phototherapy in two babies. In both infants this reaction subsided completely without sequelae. The use of Sn-protoporphyrin or related synthetic heme analogues to diminish the severity of hyperbilirubinemia in newborn infants merits further study because inhibition of the rate-limiting enzyme in the catabolism of heme to bilirubin may prove to be a useful therapeutic approach in the clinical management of neonatal hyperbilirubinemia, especially in settings in which, for social or economic reasons, other treatment modalities are not available.

ABO Blood-Group System↗
PubMed1984

Oxytocin and neonatal hyperbilirubinemia. Studies of bilirubin production.

We studied the effect of oxytocin induction or augmentation of labor on rates of bilirubin production in newborns at three different institutions. Bilirubin production, assessed quantitatively by the pulmonary excretion rate of carbon monoxide or qualitatively by the blood carboxyhemoglobin concentration, was not elevated when compared with appropriately matched control groups. Previous studies have implicated administration of large volumes of electrolyte-free dextrose solutions together with oxytocin as an important factor contributing to hemolysis in the infant. The mothers in our studies received minimal amounts of free water. We conclude that oxytocin induction or augmentation of labor does not result in neonatal hemolysis and subsequent hyperbilirubinemia when it is administered without large volumes of sodium-free intravenous solutions.

Bilirubin↗
PubMed1980

Effectiveness and safety of prenatal phenobarbital for the prevention of neonatal jaundice.

The effect of 100 mg of phenobarbital (PB) at bedtime for the last few wk of pregnancy on the incidence and severity of neonatal hyperbilirubinemia was studied. No effect was observed in the newborns of mothers who took less than ten tablets. In the 1310 newborns of adequately treated mothers (PB greater than or equal to 1.0 g), the incidence of marked jaundice (bilirubin > 16.0 mg/dl) and the need to perform an exchange transfusion were reduced by a factor of six in relation to the incidence in 1553 control infants. A randomly selected group of 415 children (182 control, 233 PB) were reexamined at 61 to 82 months of age. There was no difference in the overall morbidity and mortality between the control and treatment group. A detailed neurologic assessment failed to reveal any differences between the two groups. In the VisuoMotor Integration test, the PB group scored significantly better than the control group. In the Draw-A-Woman and the Verbal Intelligence Test, the difference was in the same direction but was not statistically significant. The degree of jaundice was not found to significantly influence the performance in the neurological examination and the intelligence tests. Sensorineural hearing defect was significantly more common in the children with moderate or marked jaundice (bilirubin > 12 mg/dl) than in those with lesser degrees of jaundice. Prenatal PB is a practical, effective, and safe method for decreasing the incidence of neonatal hyperbilirubinemia.

Bilirubin↗
PubMed1979

Mechanized determination of the apparent unbound unconjugated bilirubin concentration in serum.

The peroxidase method for determining the apparent unbound bilirubin concentration in serum has been automated by use of a programmable, computer-directed spectrophotometer. This mechanized assay determines the total bilirubin concentration and apparent unbound bilirubin concentration in serum samples and titrates the serum with bilirubin to estimate the effect of increasing total bilirubin concentrations on the apparent unbound bilirubin concentration. The entire analysis requires 0.1 mL of serum and 4 min operation time, as compared with about 30 min for the manual method. The coefficients of variation for determination of the apparent unbound bilirubin concentration in bilirubin-enriched commercial control serum were 2.8% within-day and 5.6% between-day. Bilirubin--albumin binding in serum samples from infants with severe hyperbilirubinemia was analyzed by the manual peroxidase method, the automated peroxidase method, and Sephadex gel filtration. Good correlation was found among all three methods.

Autoanalysis↗
PubMed1978

Neonatal hyperammonaemia with complete absence of liver carbamyl phosphate synthetase activity.

Two newborn infants, male (A) and female (B), with lethal hyperammonaemia are described in the same family. In both, symptoms started on the second day of life. Lethargy and hypotonia were the most prominent initial findings and were followed by convulsions and coma. In both, blood ammonia levels rose to 570 mumol/u (795 microgram/100 ml) a few hours before death, which occurred on the third and fourth day of life respectively. Assay of liver urea cycle enzymes in baby B showed a complete absence of mitochondrial carbamyl phosphate synthetase activity.

Amino Acid Metabolism, Inborn Errors↗