Oxygen-hemoglobulin dissociation curves: effect of inherited enzyme defects of the red cell.

The blood of a patient with a deficiency of hexokinase in the red cells and a decreased concentration of 2, 3-diphosphoglycerate in the red cells showed an increased affinity for oxygen, whereas a patient with a deficiency of pyruvate kinase and an elevated concentration of 2, 3-diphosphoglycerate in the red cells had blood with a decreased affinity for oxygen. Defects in red cell glycolysis may alter the oxygen affinity of blood by virtue of their effect on 2, 3-diphosphoglycerate concentrations in red cells.

Hexokinase isoenzymes in human erythrocytes: association of type II with fetal hemoglobin.

Hexokinase activity in human erythrocytes is associated with three electrophoretically distinct bands. Normal adult erythrocytes contain hexokinases Types I and III. Type II hexokinase is present in the erythrocytes of newborn infants and absent from those of normal adults; it is, however, present in erythrocytes of adults with hereditary persistence of fetal hemoglobin. Type II hexokinase and fetal hemtoglobin appear to be associated.

Oxygen affinity in red cells: changes induced in vivo by propranolol.

Propranolol, a blocking agent for the beta adrenergic receptor, produces a redistribution of 2,3-diphosphoglycerate in the red cell. At concentrations of 3.3 x10(-5)M, 2,3-diphosphoglycerate in the red cell membrane becomes unbound in vitro. The administration of propranolol to hunmns produces similar changes and results in a decrease in the affinity of hemoglobin for oxygen.

Hemoglobin Philly (beta 35 tyrosine phenylalanine): studies in the molecular pathology of hemoglobin.

An abnormal unstable hemoglobin, hemoglobin Philly, was found in three members of a family, each of whom had evidence of a chronic hemolytic state. The presence of the mutant protein was suggested by the rapid appearance of inclusion bodies upon incubation of erythrocytes with brilliant cresyl blue and by the increased heat precipitability of the hemoglobin. However, no abnormal hemoglobin could be demonstrated by electrophoresis or column chromatography. Sulfhydryl titration of the hemolysates with p-mercuribenzoate indicated that there was an average of four reactive sulfhydryl groups per hemoglobin molecule instead of the usual two. The total number of hemoglobin sulfhydryl groups was normal; six groups were measured when denatured globin was reacted with 5,5'-dithiobis[2-nitrobenzoic acid]. This indicated that the increased sulfhydryl reactivity was due to an increased availability to p-mercuribenzoate of the usually unreactive hemoglobin cysteines at beta112 and alpha104. After treatment for (1/2) hr with 4-5 moles of p-mercuribenzoate per mole of hemoglobin, electrophoresis revealed that 30-35% of the hemoglobin had been dissociated into alpha- and beta-chains. Normal hemolysates revealed negligible splitting after 72 hr of similar treatment. The alpha- and beta-chains of hemoglobin Philly were separated from the unsplit hemoglobin A by carboxymethyl cellulose chromatography. Fingerprint and amino acid analyses revealed that tyrosine beta35 was replaced by phenylalanine. In hemoglobin Philly there is loss of the normal hydrogen bond between the tyrosine hydroxyl group and the carboxyl group of aspartic acid alpha126 at the alpha(1)beta(1) contact. This shifts the equilibrium from hemoglobin tetramers toward monomers, exposing the beta112 and alpha104 cysteines. In the cell, precipitation of the unstable monomers may contribute to erythrocyte destruction.

The effects of deoxygenation of adult and fetal hemoglobin on the synthesis of red cell 2,3-diphosphoglycerate and its in vivo consequences.

Patients over 1 month of age with arterial oxygen pressures of less than 60 mm Hg were found to have elevated red cell 2,3-diphosphoglycerate (2,3-DPG) levels and blood with a decreased affinity for oxygen. The increase in 2,3-DPG was proportional to the degree of hypoxemia. In patients under 1 month of age this relationship was not observed. Red cells from adults, but not newborns, showed rapid increases in 2,3-DPG when incubated under nitrogen. Adult, but not fetal, deoxyhemoglobin was shown to facilitate in vitro synthesis of 2,3-DPG by binding this organic phosphate and relieving the product inhibition of 2,3-DPG mutase. Throughout a wide range change in oxygen affinity as measured by the P(50) is linear with respect to the 2,3-DPG concentration; a change of 430 mmumoles of 2,3-DPG/ml of red blood corpuscles (RBC) resulting in a change of the P(50) of 1 mm Hg. It appears that the 2,3-DPG of the adult's red cells responds rapidly to metabolic and environmental influences and in turn effects metabolism and the cellular environment. Many of these effects are not shared by the red cells of the newborn.

Hemoglobin Syracuse (alpha2beta2-143(H21)His leads to Pro), a new high-affinity variant detected by special electrophoretic methods. Observations on the auto-oxidation of normal and variant hemoglobins.

Family members from four generations were found to have polycythemia and increased whole blood O2 affinity (P50; 11 mm Hg; normal, 27 mm Hg). No abnormal hemoglobin bands were seen after electrophoresis on starch gel at pH 8.6 or agar gel at pH 6.0. Analysis of the oxygenated hemolysate by isoelectric focusing on polyacrylamide gel revealed two closely spaced bands. When deoxygenated hemolysate was analyzed in oxygen-free gels, the two components were more widely separated. About 40% of the patient's hemoglobin focused at a more acid pH than hemoglobin A, indicating a hemoglobin variant with impaired Bohr effect. Chromatography of globin in 8 M urea revealed two beta-chain peaks, the first of which was eluted at a lower buffer molarity than normal beta chain. Fingerprints of tryptic digests of the aminoethylated chains were done on silica gel thin-layer plates. Tp 14 from the abnormal beta chain had slower electrophoretic mobility and a greater Rf value. Amino acid analyses of this peptide gave values identical with those of betaTp 14, except that it contained one proline residue and no histidine. Since the one His in betaTp 14 is in position 143, hemoglobin Syracuse in alpha2beta2-143 His leads to Pro. Native Hb Syracuse could be separated from hemoglobin A on a carboxymethylcellulose column. The inclusion of 0.1 mM EDTA in the preparative buffers proved very useful in reducing the formation of methemoglobin. Oxygen equilibria of purified hemoglobin Syracuse showed high oxygen affinity (P50 value 12% that of hemoglobin A) and lack of cooperativity between subunits (Hill's n equals 1.1). The alkaline Bohr effect was about half that of hemoglobin A. The proline substitution at betaH21 disrupts the helical configuration and probably prevents the formation of salt bonds that are important in stabilizing the deoxy structure and contribute to the alkaline Bohr effect. Since beta143 His is a binding site for 2,3-diphosphoglycerate (2,3-DPG), it is not suprising that hemoglobin Syracuse had markedly impaired reactivity with 2,3-DPG. Hemoglobin Syracuse auto-oxidized more slowly than hemoglobin A, probably reflecting a slower rate of dissociation of oxygen from fully liganded hemoglobin.

Metabolic alterations in the human erythrocyte produced by increases in glucose concentration. The role of the polyol pathway.

Human erythrocytes incubated in medium containing 50 mM glucose have increased intracellular sorbitol and fructose concentrations as compared with samples incubated with 5 mM glucose. Increased medium glucose concentration did not significantly alter total glucose consumption or lactate production. However, the intracellular lactate:pyruvate ratio rose, the concentrations of fructose diphosphate, and triose phosphates increased, and the 2,3-diphosphoglycerate concentration fell. [(14)C]O(2) production from glucose-1-(14)C also increased with increased medium glucose concentration. These changes are believed to reflect changes in the redox states of the diphosphopyridine nucleotide/reduced form of diphosphopyridine nucleotide (NAD/NADH) and nicotinamide-adenine dinucleotide phosphate/reduced form of nicotinamide-adenine dinucleotide phosphate (NADP/NADPH) couples resulting from increased activity of the polyol pathway. Addition of pyruvate to the incubation media prevented these changes. These studies illustrate that an increase in the red cell's normal substrate, glucose, can produce changes in red cell metabolism.

Is bovine milk a health hazard?

Whole bovine milk should not be fed to infants during the first year of life because of its association with occult gastrointestinal bleeding, iron deficiency anemia, and cow's milk allergy. The consumption of whole milk after the first year of life should be discouraged because of its potential role in a variety of disorders including atherosclerosis, recurrent abdominal pain of childhood, cataracts, milk-borne infections, and juvenile delinquency.

Kernicterus in preterm newborns: past, present, and future.

This historical overview of kernicterus in prematurity, from the 1950s to the present, provides a unique perspective on this clinical conundrum. Three separate periods of pediatric history are detailed in relationship to our understanding of kernicterus in the preterm newborn: (1) the pre-intensive care era (1950 to 1965); (2) the low bilirubin kernicterus era (1965 to 1982); and (3) the 1980s. Each period demonstrates selected insights regarding kernicterus in prematurity, and together with recent reports suggest that premature newborns are now at extremely low risk of developing kernicterus when managed using current standards of care. However, the current conservative empiric guidelines for preventing kernicterus are questioned, and it is suggested that additional study is needed to clarify this issue in the 1990s.

Henna: a potential cause of oxidative hemolysis and neonatal hyperbilirubinemia.

OBJECTIVE: To evaluate the in vitro oxidation potential of lawsone (2-hydroxy-1,4 naphthoquinone). Lawsone is a chemical present in henna, the crushed leaves of which are used worldwide as a cosmetic agent to stain the hair, skin, and nails. METHODOLOGY: Venous blood from glucose-6-phosphate dehydrogenase (G6PD)-normal and G6PD A- subjects were incubated with various amounts of lawsone for 2 hours at 37 degrees C. Reduced glutathione and methemoglobin (MHb) levels were measured before and after incubation. RESULTS: Final molar concentrations of lawsone in normal blood of 1.4, 2.8, 5.7, and 8.6 x 10-3 mol/L increased MHb percentages from 0.5% to 2.2%, 8.3%, 9.5% and 12.5%, respectively. In a C6PD A- blood, MHb percentages were 19.8%, 32.2%, 44.9%, and 53.9%. At a lawsone concentration of 2.8 x 10-3 mol/L, blood from 15 healthy adults formed MHb percentages of 7.4% +/- 3.3% (+/- 1 SD); in blood from 4 G6PD A- adults, percentages were 44.5%, 40.6%, 41.3%, and 42.8%. Simultaneous measurements of reduced glutathione revealed preincubation values of greater than 40 mg/100 mL of red cells in blood of healthy and G6PD A- subjects. Postincubation values were greater than 40 in blood of healthy subjects and less than 40 in blood of G6PD A- subjects. CONCLUSIONS: These in vitro observations indicate that lawsone is an agent capable of causing oxidative hemolysis. In regions of the world where there is a high incidence of G6PD deficiency and unexplained hyperbilirubinemia, oxidative hemolysis secondary to the cutaneous application of henna could be the initiating event.

Differences in polymorphonuclear cell counts between healthy white and black infants: response to meningitis.

Both black adults and black children have significantly lower total WBC counts and absolute polymorphonuclear WBC counts than do white adults and white children. In an effort to determine whether similar differences existed in infancy, 50 health black infants and 50 white infants were examined. The black infants, 9 to 12 months of age, were found to have significantly lower total WBC counts, absolute neutrophil counts, and absolute lymphocyte counts. In ten of the 50 black infants, the absolute neutrophil counts were less than 1,000/microL; none of the white infants had absolute neutrophil counts of less than 1,000/microL. Even in the presence of a serious infection, meningitis, significantly fewer black infants had absolute neutrophil counts greater than 10,000/microL than did their white counterparts.

Iron status and infant feeding practices in an urban ambulatory center.

The relationship of infant feeding practices to iron status was examined in a group of 280 infants, 9 to 12 months of age, attending a "well-baby" clinic. Of this group, 7.6% were found to be iron depleted, 19.7% were iron deficient without anemia, and 8.2% were iron deficient with anemia. The incidence of iron-deficiency anemia was significantly greater in the black infants than the white infants (14.3% v 2.7%). The introduction of whole cow's milk into the diet had occurred prior to 6 months of age in 29.2% of the infants, and 62.1% of these infants had laboratory evidence of nutritional iron inadequacy, as contrasted with only 21.8% of those with iron deficiencies fed cow's milk after 6 months of age. Of the 21 infants with iron-deficiency anemia, 19 (90.5%) had been fed whole cow's milk prior to 6 months of age. Iron deficiency remains a nutritional problem for infants in an urban setting and is largely a result of the early introduction of whole cow's milk into the diet.

A survey of pediatric resident training programs 5 years after the Task Force report.

Twenty-nine pediatric residency training programs responded to a survey with detailed descriptions of the scheduled rotations before and after the Report of the Task Force on Pediatric Education. This survey documented some changes in the overall structure of residency programming in that all programs demand 3 years of general pediatric training. Little if any changes were noted in the traditional emphasis on inpatient and neonatal training. Some changes in content area have been noted, namely a modest increase in the experiences in adolescent medicine. The survey failed to demonstrate any trend indicating increased emphasis on training experiences in the "new morbidity."

The "In-Training Examination" of the American Board of Pediatrics: does it test for "new" or "old" information?

The American Board of Pediatrics In-Training Examination or "Pre-Test" is not in widespread use as a means of evaluating the cognitive knowledge and problem-solving skills of hourse officers. The examination is modeled after the certifying examination of the American Board of Pediatrics. The 1977 Pre-Test was analyzed in an attempt to determine whether awareness of recent medical knowledge was required to pass this examination. The 7th through 10th editions of the Nelson Textbook of Pediatrics were used as a reference source. These editions represent information that is from 5 to at least 20 years of age. Analysis of the 190 items revealed that the correct answer was known for 148 or 78% of the questions at least 20 years ago. These results suggest that the Pre-Test, and presumably the American Board of Pediatrics certifying exam, measures the candidates' knowledge of long-standing core information.

Anemia with Haemophilus influenzae meningitis.

The hematologic values in patients with Haemophilus influenzae meningitis were contrasted with those of patients with other types of bacterial meningitis and aseptic meningitis in an attempt to determine whether anemia is either specific for or more common in patients with H influenzae meningitis. Patients with H influenzae meningitis had significantly lower admission hemoglobin values because they were significantly younger than the other two groups. The H influenzae meningitis patients with the lowest hemoglobin values on admission had been sicker for longer periods prior to diagnosis and had higher initial white cell counts. Patients with H influenzae meningitis, aged 3 to 24 months, developed lower hemoglobin values during hospitalization than did patients with other forms of meningitis. Anemia occurs with all forms of bacterial meningitis but is uncommon in aseptic meningitis. The anemia observed in patients with H influenzae meningitis, particularly those less than 2 years of age, is generally more severe than that observed in other forms of bacterial meningitis.

Controversies in the management of acute idiopathic thrombocytopenic purpura: a survey of specialists.

A total of 322 physicians, Board-certified in pediatric hematology, responded to a survey designed to determine several aspects of their management of children with acute idiopathic thrombocytopenic purpura. The survey demonstrates that, in practice among specialists, a controversy exists as to whether or not bone marrow examination needs to be performed, and how often corticosteroids should be prescribed. Seventy-four percent of practitioners would perform the bone marrow examination, whereas 26% would not do so. Forty-six percent of responders prescribe steroids more than half the time, whereas 54% prescribe steroids less than half the time. The questionnaire ascertained the reasons why physicians performed marrow aspirations and prescribed steroids.

Differentiation of orbital cellulitis from preseptal cellulitis by computed tomography.

Computed tomography (CT) was used in the management of four patients with periorbital inflammation. These patients were selected for CT scanning because of the difficulty, on clinical examination alone, in determining the degree of orbital disease. The CT scans confirmed the presence and defined the location of an orbital abscess in three patients and eliminated the presence of an abscess in the fourth. On the basis of this experience, CT scanning is recommended in the evaluation of children with periorbital inflammation in whom proptosis, ophthalmoplegia, or loss of visual acuity develops, or in whom severe eyelid edema prevents adequate eye examination.

Effect of iron therapy on behavior performance in nonanemic, iron-deficient infants.

In an effort to determine whether iron deficiency, in the absence of anemia (hemoglobin greater than 11.0 g/dL), might produce alterations in behavioral development, four groups of nonanemic infants, 9 to 12 months of age, with varying degrees of iron deficiency were studied. Infants were classified as iron sufficient, iron depleted, or iron deficient based on measurements of serum ferritin concentration, erythrocyte protoporphyrin values, and the mean cell volume of erythrocytes. Subjects in each group were tested with the Bayley Mental Development Index, treated with parenteral iron, and retested seven days later. The administration of iron produced a significant increase in the Mental Development Index scores (+21.6 points) in the infants with iron deficiency but no significant change in the scores of infants with iron sufficiency (+6.2 points) or only iron depletion (+5.6 points). It is concluded that iron deficiency, even in the absence of anemia, results in biochemical alterations that impair behavior in infants.

Iron sufficiency in breast-fed infants and the availability of iron from human milk.

Four infants were studied who had been exclusively breast-fed for periods varying from 8 to 18 months. All had grown sufficiently to have exhausted their prenatally acquired iron endowment with respect to meeting current needs for maintaining normal hemoglobin levels. All infants had normal hemoglobin values and normal serum iron values. Studies of iron absorption from breast milk and cow's milk were performed in ten normal adults. The absorption of iron from the human milk was significantly higher. These findings suggest that the iron present in human milk is sufficient to meet the iron requirements of the exclusively breast-fed infant until he approximately triples his birthweight.

Vitamin E and neonatal hemolysis.

A study was designed to determine if the presence of vitamin E deficiency during the first week of life played a contributory role in the shortened red cell life span observed in the premature infant. Carboxyhemoglobin values were used as an index of hemolysis. Ten infants received vitamin E administered intramuscularly in a total dose of 125 mg/kg during days 3 to 7 of life; ten infants served as controls. The mean percent carboxyhemoglobin level fell significantly from day 3 to day 8 in the treated group (1.08% to 0.78%) whereas the mean value remained unchanged at 0.96% in the control group. The administration of vitamin E appears to reduce but not eliminate the accelerated red cell destruction that characterizes the preterm infant. Pediatrics, 59:995-997, 1677, VITAMIN E, HEMOLYSIS, PREMATURE INFANT, CARBOXYHEMOGLOBIN.