摘要:

In view of previous studies which did not show a precise relation between the percentage fetal hemoglobin and the position of the oxygen hemoglobin equilibrium curve, this problem was reexamined taking into account both the concentration of fetal hemoglobin and the 2,3-diphosphoglycerate (2,3-DPG) content of the cell.Forty-eight normal infants weighing 2500 g or more at birth were studied on days 1 and 5 of life and then at 3 and 6–9 weeks, and at 3–4, 5–6, and 8–11 months of age. Fifty-six ingfants ranging in birth weight from 900 to 2420 g were studied during the first 8 days of life and then at 2− to 3-week intervals until approximately 16 weeks of life. Twelve premature infants who were ill with the respiratory distress syndrome were also studied.Laboratory procedures consisted of measurement of total hemoglobin, fetal hemoglobin, red cell 2,3-DPG, and oxygen equilibrium curves.The “functioning DPG fraction” in millimicromoles per milliliter red blood cells (RBC) was obtained by multiplication of the total red cell DPG content (millimicromoles per milliliter RBC) by the percentage of adult hemoglobin.These studies confirm previous observations that the term infant begins life with blood that has an increased affinity for oxygen. During the first few months of life the oxygen-hemoglobin equilibrium curve gradually shifts to the right and between 4 and 6 months of age becomes similar to that observed in the normal adult.The change in P60in these infants correlated neither with the change in red cell DPG content alone nor with the decline in fetal hemoglobin alone. Instead, the progressive decrease in oxygen affinity during the first 6 months of life correlated significantly (r= 0.876,P< 0.001) with the functioning DPG fraction. The term “functioning DPG fraction” is suggested to reflect the fact that both the DPG concentration and the adult hemoglobin concentration within the cell, with which the DPG interacts, are necessary factors in determining the position of the oxygen equilibrium curve.Infants with respiratory distress appear to have P50s that are lower than those of healthy infants of similar gestational age and birth weight. This appears to be primarily a result of a decrease in red cell DPG concentration. It is this type of infant who may benefit from exchange transfusion with fresh adult blood.

ISSN:0031-3998    

出版商:OVID    

年代:1971

数据来源: OVID

摘要:

Specific antibody production by spleen cells of male and female mice during a noninvasive enteric infection withEscherichia coliand after parenteral injection of heat-killedE. coliwas studied by use of the Jerne-Nordin agar plaque technique. Following experimental enteric colonization withE. coli0127 significantly greater proportions of spleen cells produced specific anti-0 antibody in immature weanling female mice than in their male littermates. Anti-E, coli0127 plaque-forming cells were also found in significantly greater numbers in the spleens of immature females than in males following intraperitoneal injection of small numbers of heat-killedE. coli.Although many spleens from male mice produced no cell plaques after a small dose of antigen, responses by the sexes were comparable after injection of large numbers of heat-killed bacteria.Production of plaques by spleen cells from female animals after injection of small amounts of antigen increased significantly with age, but the responses observed in adult male mice were only slightly and insignificantly greater than those of male weanlings. Studies of the sizes of plaques produced by spleen cells of male and female animals showed no statistical differences. Young ovariectomized females responded in the same way as their sham-operated male littermates to small amounts ofE. coliantigen. Administration of small doses of estrogen increased plaque formation by spleen cells of weanling males.It appears that an effect of female sex hormones is production of greater numbers of antibody-producing cells; yet in the final phase of antibody production, individual cells from each sex produce on the average the same amounts of antibody.SpeculationThe better ability of the immature female to respond immunologically to a small amount ofE. coli0 antigen may be a significant factor in her superior resistance to invasive disease withE. coli.Differences in the immune response of the two sexes appear to occur in the proliferative phase of antibody-producing process or steps leading up to this phase, but not in the final phases of antibody production by the cell. By mechanisms not yet defined, estrogen appears to enhance the proliferation of immunocompetent cells, and secretion of estrogen by the female may explain her superior immunologic responsiveness.

ISSN:0031-3998    

出版商:OVID    

年代:1971

数据来源: OVID

摘要:

A Negro female with congenital nonhemolytic jaundice (Crigler-Najjar syndrome) was studied over a period of 15 months. During this period the plasma bilirubin concentration averaged 20.6 mg/100 ml. Administration of phenobarbital did not lower the bilirubin concentration. Studies with isotopically labeled bilirubin showed that phenobarbital had not increased the fractional rate of elimination of bilirubin, and the patient's bilirubin production rate while receiving phenobarbital therapy (3.5 mg/kg/24 hr) was not increased over that seen in normal individuals (3.8 \pm 0.6 mg/kg/24 hr, mean \pm sd).Multicompartmental analysis of the patient's labeled bilirubin clearance data, as well as that from two other reported cases of congenital nonhemolytic jaundice, did not furnish new information on pathways of bilirubin catabolism but did demonstrate that the fractional transfer rate of bilirubin from plasma to liver for all three subjects (0.42–0.87 hr-1) was reduced compared with the range seen in normal individuals (0.9–2.0 hr-1). This finding may reflect saturation of either the hepatic uptake process or intracellular binding sites, in the face of a serum bilirubin concentration 20–40 times normal.Menthol conjugation in the patient's parents was normal, unlike reported findings in parents of children with congenital nonhemolytic jaundice unresponsive to phenobarbital therapy. Labeled bilirubin clearances in the parents demonstrated an abnormality in the mother's pattern of clearance, whereas the father's clearance was normal.The patient was found to excrete normal amounts of testosterone conjugated with glucuronic acid, demonstrating that the defect in glucuronide conjugation does not include all physiological compounds.SpeculationPlasma clearance studies with labeled bilirubin can aid in the investigation of modes of inheritance of unconjugated hyperbilirubinemia.

ISSN:0031-3998    

出版商:OVID    

年代:1971

数据来源: OVID

摘要:

Patients with homocystinuria and a normal subject excreted cystathionine (1.8–15.0 μmoles/hr) after oral administration of homoserine plus cysteine; administration of both precursors is necessary. Excretion in the urine of the next higher homologue of cystathionine, homolanthionine, was found to occur spontaneously (0.8–1.5 μmoles/hr), but not constantly, in three of seven patients with homocystinuria; loading with homoserine increased homolanthioninuria (2.9–5.7 μmoles/hr).Optimum conditions were established in crude extracts of rat liver forin vitrosynthesis of cystathionine from homoserine and cysteine (reverse cystathionase) and of homolanthionine from homoserine and homocysteine. Under these conditions, a greater capacity for synthesis of cystathionine by reverse cystathionase (1856 mμmoles/mg protein/hr \pm 95) than for its cleavage in the forward direction (951 mμmoles/mg protein/hr \pm 26) was demonstrated in liver; brain showed barely measurable activity in either direction. In crude extracts of livers from two patients with homocystinuria, activity of reverse cystathionase (39 and 56 mμmoles/mg protein/hr) was less than cleavage (144 and 396 mμmoles/nig protein hr), and both activities were far less than that found in rat liver extracts under the same conditions.Homolanthionine synthesis in rat brain was almost nil; in the other rat organs, it was far less than cystathionine synthesis by reverse cystathionase (compare 69 mμMoles/mg protein/hr \pm 2 in rat liver); it was greater in extracts of rat liver than in extracts of human liver (6.7–10.8 mμmoles/mg protein/hr in human liver); it was virtually absent from the liver of the vitamin B6-deficient rat, but activity was restored by pyridoxal phosphate addedin vitro.Homolanthionine synthesis activity in rat liver was separated from cystathionine synthase by ammonium sulfate fractionation (Table IX); it was not separated from cystathionase by such fractionation or by chromatography on carboxymethylcellulose (Fig. 3).SpeculationAlthough administration of homoserine and cysteine results in urinary excretion of cystathionine by both normal subjects and those with homocystinuria, it is improbable that this treatment would promote the formation of any considerable amount of cystathionine in the brain, since evidence from rat studies indicates that the necessary

ISSN:0031-3998    

出版商:OVID    

年代:1971

数据来源: OVID

摘要:

Meconium, newborn stool, and fetal bile were examined for bile acids by the techniques of gas liquid chromatography, thin layer chromatography and colorimetric spectrometry. Cholic, chenodeoxycholic, deoxycholic, and lithocholic acid were detected in meconium. Secondary bile acids were not present in significant amounts in either stool or fetal bile from newborns. During fetal development more cheno-deoxycholate than cholate is formed. The presence of secondary bile acids in meconium is suggestive of maternal-to-fetal transfer via the placenta.SpeculationThe number of hydroxyl groups on the basic sterol nucleus may influence bile duct development. Excess quantities of bile acids, particularly lithocholic acid, may alter the developing fetal hepatic stucture.

ISSN:0031-3998    

出版商:OVID    

年代:1971

数据来源: OVID