Cerebral vasoreactivity and internal carotid artery flow help to identify patients at risk for hyperperfusion after carotid endarterectomy

BACKGROUND AND PURPOSE

Hyperperfusion syndrome is a rare but potentially devastating complication after carotid endarterectomy (CEA). The aim of this study was to investigate whether preoperative measurement of cerebral vasoreactivity (CVR) and intraoperative measurement of internal carotid artery (ICA) flow could identify patients at risk for hyperperfusion after CEA.

METHODS

For 26 patients with unilateral ICA stenosis >/=70%, cerebral blood flow (CBF) and CVR were investigated before and 1 month after CEA, with resting and acetazolamide-challenge single-photon emission CT. CBF on the first postoperative day was also measured. ICA flow was measured before and after reconstruction by electromagnetic flowmeter during surgery.

RESULTS

Ipsilateral CBF on the first postoperative day significantly increased relatively (56.6+/-53.2%) as well as absolutely (37.9+/-8.8 to 57.7+/-18.0 mL/100 g per minute) in the reduced CVR group (CVR <12%) but not in the normal CVR group (CVR >/=12%) (10.3+/-15.5% and 40.6+/-7.9 to 43.9+/-5.7 mL/100 g per minute, respectively). One month later, this difference almost disappeared. Two patients showed ipsilateral CBF increase of >/=100%. A significant association of intracerebral steal with hyperperfusion (CBF increase >/=100%) on the first postoperative day was also observed. ICA flow increase after reconstruction significantly correlated with CBF increase on the first postoperative day in the reduced CVR group but not in the normal CVR group. The threshold of ICA flow increase for hyperperfusion was estimated to be 330 mL/min in the reduced CVR group.

CONCLUSIONS

Single-photon emission CT with acetazolamide challenge and ICA flow measurement during surgery could identify patients at risk for hyperperfusion after CEA, in whom careful monitoring and control of blood pressure should be initiated even intraoperatively.

Neonatal lupus erythematosus: analysis of HLA class I genes in Japanese child/mother pairs

Neonatal lupus erythematosus (NLE), characterized by two major symptoms of congenital heart block (CHB) and transient cutaneous lesions, is an antibody mediated disorder due to placentally transmitted maternal autoantibodies to Ro/SSA and/or La/SSB. We genotyped 14 mothers, 9 children with CHB, 8 with cutaneous NLE only and 5 asymptomatic siblings at HLA class I loci, by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) combined with sequence-specific amplification. Mothers of children with NLE exhibited a very high polymorphism of HLA class I genes. Significant increases of HLA-B*1501 (B62) and Cw*0303 (Cw9) with absence of HLA-A1/B8 haplotype in Japanese mothers differed from the serologically defined HLA class I profiles among NLE mothers in white and North American black populations. Child/mother heterozygous HLA-A/B/C haplotype identity, which extended to HLA-class II DR/DQ loci, was observed in only one of 9 cases with CHB. No association was found between HLA class I alleles of children and the symptoms of NLE. These findings provide for the opportunity to investigate the primary genetic associations with NLE/CHB in different ethnic groups.

Neonatal lupus erythematosus: results of maternal corticosteroid therapy

OBJECTIVE

To assess the possibility of preventing cardiac or cutaneous manifestations of neonatal lupus erythematosus or treating the fetus with congenital heart block by administering corticosteroid therapy to the mother.

METHODS

Eighty-seven offspring of 40 anti-Ro/SSA-positive mothers, followed up from 1979 to 1996, were evaluated. Autoantibodies against Ro/SSA and La/SSB antigens were detected by immunodiffusion and enzyme-linked immunosorbent assay.

RESULTS

None of 26 neonates whose mothers received corticosteroid maintenance therapy initiated before 16 weeks' gestation demonstrated congenital heart block, whereas 15 of 61 neonates whose mothers received no corticosteroids during pregnancy or began receiving steroid therapy after 16 weeks' gestation had congenital heart block. Complete congenital heart block, once developed, did not respond to corticosteroid treatment in utero. Four infants whose mothers received steroid treatment before 16 weeks' gestation had skin lesions of neonatal lupus erythematosus.

CONCLUSION

Once established, complete congenital heart block was irreversible and maternal corticosteroid therapy did not effectively prevent cutaneous lupus erythematosus. However, prenatal maintenance therapy with prednisolone or betamethasone given to the mother starting early in pregnancy (before 16 weeks' gestation) might reduce the risk of developing antibody-mediated congenital heart block in the offspring.

Neonatal lupus erythematosus: maternal IgG antibodies bind to a recombinant NH2-terminal fusion protein encoded by human alpha-fodrin cDNA

IgG antibodies to a cleavage product of alpha-fodrin (120 kDa alpha-fodrin) have recently been identified as organ-specific autoantibodies in primary Sjögren's syndrome. In this study, we examined seroreactivity of mothers and infants with neonatal lupus erythematosus (NLE) to a recombinant NH2-terminal protein (120 kDa alpha-fodrin) of human alpha-fodrin. Serum samples were collected during the perinatal period in seven pregnancies of five mothers delivering offspring with NLE. Anti-120 kDa alpha-fodrin antibodies were identified by immunoblotting in six of seven perinatal maternal sera of offspring with NLE: one of two congenital heart block offspring and all five offspring with cutaneous NLE. These antibodies were placentally transmitted to infants. One of the five mothers had primary Sjögren's syndrome, and four were asymptomatic. One asymptomatic mother did not demonstrate anti-120 kDa alpha-fodrin activity at the time of the first delivery of a congenital heart block infant, but was found to be positive at the time of subsequent delivery of a second child with cutaneous NLE. We propose that maternal antibodies to 120 kDa alpha-fodrin may be an additional serologic marker for the risk of NLE in anti-Ro/SS-A positive women.

Polymorphisms of HLA class II genes and autoimmune responses to Ro/SS-A-La/SS-B among Japanese subjects

OBJECTIVE

To investigate HLA class II allele associations with autoantibody responses to Ro/SS-A and La/SS-B among Japanese subjects.

METHODS

Haplotype and allele distributions, along with molecular polymorphisms, of HLA class II genes were analyzed by polymerase chain reaction-restriction fragment length polymorphism in 41 Japanese women with precipitating autoantibodies to Ro/SS-A and/or La/SS-B.

RESULTS

Among women with both Ro/SS-A and La/SS-B antibodies, the HLA class II haplotype DRB1*08032/DQA1*0103/DQB1*0601 and DRB1*08032 allele showed significantly increased frequencies compared with patients with anti-Ro/SS-A alone or with normal controls. All women with both anti-Ro/SS-A and anti-La/SS-B, but not those with anti-Ro/SS-A alone, carried DRB1 alleles that shared the same amino acid residues at positions 14-31 and 71 of the hypervariable regions of the DRB1 chain. All anti-Ro/SS-A positive women carried 1 or 2 alleles of DQB1*06 and DQB1*03 subtypes that shared the same amino acid residues at positions 71-77 of the DQB1 chain. HLA class II allele distributions did not differ among 3 anti-Ro/SS-A positive groups with different disease expressions, i.e., patients with systemic lupus erythematosus, patients with primary Sjögren's syndrome, and women with no apparent symptoms of rheumatic disease.

CONCLUSION

HLA class II allele distributions differ among anti-Ro/SS-A positive subjects according to the presence or absence of coexisting anti-La/SS-B antibodies, but not according to disease expression. Our findings suggest that different HLA class II molecules might control the development of anti-Ro/SS-A and/or anti-La/SS-B antibodies in the autoimmune response to the Ro/SS-A-La/SS-B complex.

Neonatal lupus erythematosus: studies on HLA class II genes and autoantibody profiles in Japanese mothers

Neonatal lupus erythematosus (NLE) is a rare disorder of neonates characterized by two major clinical manifestations: congenital heart block and cutaneous lupus lesions. The disease is associated with placentally transferred maternal anti-Ro/SSA and/or La/SSB antibodies. To clarify possible class II HLA associations with maternal autoantibody responses, haplotypic and allelic distributions, along with the polymorphism of the MHC class II HLA alleles, were analyzed based on PCR-RFLP results in 25 Japanese mothers of two groups defined by precipitating autoantibody profiles. Among mothers with both anti-Ro/SSA and anti-La/SSB antibodies, but not those with anti-Ro/SSA alone, the class II haplotypes DRB1*1101-DQA1*0501-DQB1*0301 and DRB1*08032-DQA1*0103-DQB1*0601 as well as individual class II alleles DRB1*1101, DRB1*08032 and DQB1*0301 showed significantly increased frequencies compared to those in normal controls. All anti-Ro/SSA and anti-La/SSB positive mothers carried DRB1 alleles that shared the same amino acid residues at positions 14-31 and 71 of the DRB1 chain. These mothers also carried homozygous or heterozygous DQ6 and DQ3 alleles that shared the same amino acid residues at positions 27-36 and 71-77 of hypervariable regions of the DQB1 chain. Furthermore, all mothers with both anti-Ro/SSA and anti-La/SSB were homozygous for DPB1*0501. Nine of 10 anti-Ro/SSA and anti-La/SSB-positive mothers, but only 6 of 15 mothers with anti-Ro/SSA alone, had affected infants. Thus, our findings suggest that there may be immunogenetic differences among mothers according to their autoantibody profiles, and that mothers with both anti-Ro/SSA and anti-La/SSB are more likely to have infants with NLE than mothers with anti-Ro/SSA alone.

[A case of congenital complete heart block in a mother with anti-52 kD SS-A/Ro antibodies]

We report a case of congenital complete heart block (CCHB). A 38-year-old woman was admitted our hospital because of fetal bradycardia at 21 weeks 3 days of gestational age. She had no symptom of collagen disease. On admission, laboratory data showed positive anti-nuclear antibodies, anti-SS-A/Ro antibodies and anti-52 kD SS-A/Ro antibodies. But anti-60 kD SS-A/Ro and anti-SS-B/La antibodies were negative. Consequently anti-52 kD SS-A/Ro antibodies positive woman had an infant with CCHB. The baby was equipped with pacemaker at the age of 2 months. This report suggests that anti-52 kD SS-A/Ro antibodies may play an important role in the development of CCHB.

Neonatal lupus erythematosus: HLA-DR and -DQ distributions are different among the groups of anti-Ro/SSA-positive mothers with different neonatal outcomes

Neonatal lupus erythematosus (NLE) is an antibody-mediated disorder of infants characterized by two major clinical manifestations; cutaneous lupus lesions and congenital heart block (CHB). The disease is associated with placentally transferred maternal anti-Ro/SSA and/or La/SSB antibodies. There is a tendency for the same disease expression to occur within a sibship. To reveal a possible association of class II MHC genes with maternal anti-Ro/SSA autoimmune responses and neonatal outcomes in NLE with a relatively homogeneous ethnic background, haplotype, and allele distributions were analyzed based on the PCR-RFLP results in 26 Japanese anti-Ro/SSA-positive mothers from three groups defined by neonatal outcomes. The results were as follows: (i) maternal HLA-DR5 haplotype DRB1*1101-DQA1*0501-DQB1*0301 and individual class II alleles making up this haplotype were significantly associated with neonatal cutaneous lupus but not CHB. Conversely, maternal HLA-DQB1*0602 carried on HLA-DR2 haplotypes was associated with CHB but not cutaneous NLE; (ii) HLA-DQA1 alleles with glutamine at position 34 of the first domain, which have reportedly been associated with the autoimmune responses to Ro/SSA antigens in other ethnic groups, were increased in the mothers of infants with cutaneous involvement; and (iii) there was no particular class II HLA profile that distinguished the disease manifestations in infants. These findings suggest that specific maternal MHC class II genes might correlate with specific neonatal outcomes in NLE.

Neonatal lupus erythematosus: analysis of HLA class II alleles in mothers and siblings from seven Japanese families

BACKGROUND

Neonatal lupus erythematosus (NLE) is a syndrome characterized by dermatitis and congenital heart block. The disease is mostly associated with transplacental passage of maternal anti-Ro(SS-A) or anti-La(SS-B) antibodies. Maternal HLA-DR3 and DQ2 alleles are associated with NLE in white and North American black populations.

OBJECTIVE

We sought evidence of a potential genetic disposition to NLE in mothers with a relatively homogeneous ethnic background.

METHODS

Class II human major histocompatibility complex HLA-DRB1, DQA1, DQB1, and DPB1 alleles were determined by polymerase chain reaction-restriction fragment length polymorphism in anti-Ro(SS-A)-positive mothers as well as in infants from seven Japanese families with siblings concordant or discordant for disease expression of NLE.

RESULTS

All seven mothers had two or three DQ alleles of DQA1 and DQB1 possessing specific amino acid residues, which are reportedly associated with anti-Ro(SS-A) autoantibody response in white and black populations. There was no class II HLA profile that distinguished disease manifestations of NLE in infants.

CONCLUSION

The HLA class II allele associations with anti-Ro(SS-A) autoantibodies that have been noted in other ethnic groups were also found in Japanese anti-Ro(SS-A)-positive mothers whose infants had NLE, suggesting shared susceptibility factors across racial barriers in maternal predisposition to Ro(SS-A) autoimmune response.

Congenital myotonic dystrophy: molecular diagnosis and clinical study

Recently, an unstable DNA fragment specific to myotonic dystrophy (MyD) was discovered. In affected individuals, a DNA fragment is found that is larger than in normal siblings. Our objectives were to show whether the results of DNA analysis agree with the disease severity and prognosis in congenital myotonic dystrophy (CMyD) by DNA analysis. We investigated three pregnancies (two studied retrospectively) in three families. We genotyped the family members with the Southern blots and the polymerase chain reaction (PCR) analysis. In one case a prenatal diagnosis was carried out using chorionic villus sampling. This report also presents the three cases of affected mothers and CMyD babies with their growth courses. We clarify four main problems in CMyD, namely, respiratory distress, delayed motor development, feeding difficulty, and delayed mental development. The allele size in the range of 10 to 13 kb tended to be present as the adult form of MyD, and 14 to 15 kb as the CMyD. The three CMyD cases whose alleles size in the range of 14 to 15 kb showed various forms of disease and prognosis. We reached the following conclusions: the disease severity and prognosis in babies with CMyD did not correlate with the result of DNA analysis. The DNA analysis is a useful test for prenatal diagnosis. However, it is impossible to predict the disease severity and prognosis in babies with CMyD.

Analysis of carbohydrate-intolerant profiles of mothers with normal glucose tolerance tests and their large for gestational age neonates

OBJECTIVE

To examine endocrine states of mothers with normal 75-g oral glucose tolerance tests (GTTs) who gave birth to large for gestational age (LGA) neonates (group I) and to examine those neonates.

METHODS

We examined plasma glucose levels and serum immunoreactive insulin responses after the 75-g oral GTT was given to group I mothers (N = 34), mothers with an abnormal oral GTT who gave birth to LGA neonates (group II, N = 21), and those with normal oral GTTs having appropriate for gestational age neonates (group III, N = 173). We also examined the infants, checking neonatal birth weight, levels of immunoreactive insulin and C-peptide immunoreactivity in cord sera at birth and the lowest blood sugar level after birth to see if a correlation existed between them.

RESULTS

Group I and II mothers showed higher titers in plasma glucose levels and remarkably enhanced ratios of 60- to 30-minute immunoreactive insulin values (immunoreactive insulin up-ratio) after load compared with those of group III mothers. Cord serum immunoreactive insulin and C-peptide immunoreactivity were significantly higher and the lowest blood sugar level was significantly reduced in group I and II neonates compared with those in group III. We observed a positive correlation between cord serum immunoreactive insulin, C-peptide immunoreactivity, and birth weight, but a negative correlation between cord serum immunoreactive insulin, birth weight, and the lowest blood sugar level in group I and II neonates (strongest tendency in group II), but not in group III neonates.

CONCLUSION

All of the abnormal carbohydrate metabolic responses in group I mothers and neonates may result in the promotion of growth in LGA fetuses similar to group II, but to a lesser extent. Identification of group I mothers by the immunoreactive insulin up-ratio after oral GTT will help predict the occurrence of LGA neonates and their possible hypoglycemia.

The influence of age and health status on the serum alpha 1-acid glycoprotein level of conventional and specific pathogen-free pigs

Serum alpha-1-acid glycoprotein (alpha 1AG) was measured in 212 Landrace White pigs between birth and finishing age. The alpha 1AG level of healthy pigs five to ten months of age was 338 +/- 79 micrograms/mL, and the upper normal limit in mature swine has been established as 500 micrograms/mL. In both specific pathogen-free (SPF) and conventional pigs, the alpha 1AG level within one day of birth was 14,263 +/- 2,393 micrograms/mL, 40 times the normal adult value, but rapidly decreased to 699 +/- 186 micrograms/mL by four weeks of age. In conventional pigs, alpha 1AG began to increase after four weeks, averaged 1,428 micrograms/mL by eight weeks, but gradually decreased to adult levels by 20 weeks of age. In comparison, alpha 1AG of SPF pigs was only 800 micrograms/mL at eight weeks and decreased more rapidly to normal by 16 weeks of age. The conventional pigs had a high incidence of clinical pneumonia and specific antibodies to Actinobacillus pleuropneumoniae and Mycoplasma hyopneumoniae at the age of eight weeks. As the clinical pneumonia disappeared, serum alpha 1AG level also gradually declined. In contrast, SPF pigs had little clinical illness, low alpha 1AG, and little serological evidence of microbial infection. Conventional pigs with nonrespiratory infections, encephalitis, or with hernias had increased alpha 1AG. While the very high alpha 1AG level of the neonatal pig may be due to genetic influences, increases later in life are likely in response to stimuli from its external environment. Monitoring of serum alpha 1AG in several herds aided in the recognition of disease processes and may have potential use in swine herd health management.

[Correlation of placental villous immaturity and dysmaturity with clinical control of maternal diabetes]

Strict clinical management of a diabetic mother who is pregnant reduces the risk of neonatal complications. It also reduces the frequency of fetal macrosomia. Diabetic mothers have a heavier placenta than mothers who are not diabetic. Light microscopic placental changes associated with diabetes include villous immaturity and dysmaturity. We have examined the placentas of 27 diabetic mothers whose maternal hemoglobin A1c (HbA1C) levels were measured throughout pregnancy. None of these placentas had a trimmed weight in excess of 600 grams. Eighteen of 27 specimens had immature villi. Four had dysmature villi. Three placentas had fibromuscular sclerosis within the villi. Five had cholangiosis and there was one cholangioma. Villous immaturity was present in 16 of 18 mothers whose HbA1C was more than 5.6% of the total hemoglobin. We found villous immaturity in 2 of 5, within 5.1-5.5% HbA1C. There was no villous immaturity in four cases whose HbA1C was less than 5.0% total hemoglobin. Our findings indicate that maternal hyperglycemia during pregnancy is associated with placental immaturity and dysmaturity.

[The relationship between ophthalmoscopic changes and classification of toxemia in toxemia of pregnancy]

Based on ophthalmoscopic findings, 30 toxemic patients were divided into three types: R-type; retinal vascular occlusion type, C-type; choroidal vascular occlusion type, R + C-type; mixed vascular occlusion type. R-type (5 cases) and R + C-type (7 cases) significantly correlated to superimposed preeclampsia. C-type (18 cases) significantly correlated to preeclampsia (pregnancy-induced hypertensive disorder: PIH). Clinical examinations (urine protein, platelet, fibrinogen, fibrin degradation product, partial thromboplastin time and prothrombin time) had no relation to the types of ophthalmoscopic classification. It was concluded that preeclampsia (PIH) and superimposed preeclampsia have different influences on the ocular fundus.

Fetal hemoglobin variants in 80,000 Japanese neonates: high prevalence of Hb F Yamaguchi (A gamma T 80 Asp----Asn)

A population-based screening of newborns for the structural variants of fetal hemoglobin was carried out in Osaka Prefecture, Japan, by isoelectric focusing of globin chains using dried blood on filter paper. Of 80,000 newborns, 18 had alpha globin variants and 55 had gamma globin variants. The incidence of gamma globin variants (1/1,455) was much higher than that of alpha globin variants (1/4,444). Structural studies were then carried out on the abnormal gamma globins in 36 samples, and revealed that 25 of them were Hb F Yamaguchi (A gamma T 80 Asp----Asn). The prevalence of this variant in Japanese was estimated to be as high as one per 2,100.

[Nonsurgical treatment of renovascular hypertension by percutaneous transluminal angioplasty]

A case of renovascular hypertension treated with percutaneous transluminal angioplasty is reported. Our patient was a 22-year-old housewife with 90 per cent stenosis of the right renal artery due to fibromuscular dysplasia. The renal artery was dilatated by percutaneous transluminal angioplasty with a Grützig balloon catheter to 25 per cent stenosis. Five hours after the procedure, blood pressure decreased from 180/114 mmHg to 130/95 mmHg; one day after, plasma renin activity fell from 4.7 ng/ml/hr to 1.7 ng/ml/hr. The patient was rehospitalized six months after percutaneous transluminal angioplasty to examine restenosis of the dilatated renal artery. Although her blood pressure remained normotensive and plasma renin activity was normal, replasty was performed since selective renal arteriography revealed 50 per cent stenosis.

Biosynthesis of hemoglobin F Malta-I in culture by adult circulating erythropoietic precursors

By using a methylcellulose clonal assay, we cultured peripheral blood erythropoietic precursors (BFU-E) from an adult couple whose child had HbF Malta-I(gamma 117 His leads to Arg), a G gamma variant, and measured the synthetic rates of HbA, HbF, and HbF Malta-I. Hemoglobin was labeled with 14C-amino acid in culture, separated by slab gel isoelectric focusing technique, and quantitated by autoradiographic or fluorographic method. Culture of BFU-E from both parents revealed significant HbF biosynthesis. HbF Malta-I was present in culture of the father's cells and comprised about 24% of total HbF. When we analyzed Hb biosynthesis in individual bursts, all bursts contained HbA and HbF in varying ratios. The frequency distribution of the individual bursts differing in percentages of HbF biosynthesis approached normal distribution. While the relative ratio of HbF Malta-I to total HbF biosynthesis in individual bursts also revealed significant variation, its frequency distribution did not show a normal distribution. There was a positive correlation between the ratios of HbF/Hb and HbF Malta-I/HbF in individual bursts.

Hemoglobin biosynthesis in individual erythropoietic bursts in culture. Studies of adult peripheral blood

By using a methylcellulose clonal assay, we cultured peripheral blood erythropoietic precursors from a patient with sickle cell anemia, a patient with sickle cell hemoglobin C disease, and a normal volunteer. We then analyzed the synthetic rates of adult and fetal hemoglobins (Hb) in individual erythropoietic bursts. Bb were labeled with 14C-amino acids in culture, separated by slab gel isoelectric focusing techniques, and quantitated by fluorographic methods. All bursts exhibited both fetal and adult Hb in varying ratios. Frequency distributions of the individual burst differing in percentage of BbF biosynthesis approached normal distributions. Further stimulation of HbF synthesis by higher erythropoietin in culture was associated with increased HbF biosynthesis in individual bursts. Augmentation of human HbF synthesis in culture appears to be controlled by qualitative intracellular changes rather than by changes in cellular population.

Hemoglobin biosynthesis in individual bursts in culture: studies of human umbilical cord blood

We cultured human umbilical cord blood erythropoietic precursors in methyl cellulose clonal assay and analyzed the synthetic rates of Hb A and Hb F in individual erythropoietic bursts. Hemoglobin was labeled with 14C-amino acids in culture, separated by slab gel isoelectric focusing techniques, and quantitated by fluorographic methods. Almost all bursts exhibited both Hb A and Hb F in varying ratios. Frequencies of the individual bursts differing in percentage Hb F biosynthesis had normal distributions. Natal erythropoietic precursors appeared to be randomly committed to Hb F synthesis.

Application of an automatic oxygenation technique to analysis of oxygen equilibrium curves for hemoglobinopathic red cells and functional screening of clinically important hemoglobinopathies

The automatic oxygenation technique of Imai et al (Biochimica Biophysica Acta, 200:189--196, 1970) was slightly modified and applied to the study of oxygen equilibrium curves of dilute, red-cell suspensions from normal subjects and individuals with hemoglobinopathies, enzymopathies, and other hematologic disorders. The p50 values of non-smoking, normal adults were 25.9 +/- 0.6 mm Hg at pH 7.4 and 37 degrees C, and corresponded to the values for whole blood reported in the literature. The oxygen equilibrium curves of suspensions from subjects with enzymopathies revealed shifts in position which are thought to be due to alterations in the concentration of 2,3-DPG of the red cells. Abnormalities in shape of the equilibrium curves were observed only for the hemoglobinopathic red cells, and could best be illustrated by the abnormally low Hill's exponent (n*). Analyses of the n* values of 34 patients with various red-cell disorders of unknown causes led to the identification of ten cases showing low values. In five of the ten patients, the presence of an abnormal hemoglobin was confirmed using column chromatography on Amberlite CG--50. These results point to the usefulness of the Hill Plot analysis of red-cell oxygen dissociation curves in functional screening for clinically important hemoglobinopathies.

Augmentation of fetal hemoglobin (HbF) synthesis in culture by human erythropoietic precursors in the marrow and peripheral blood: studies in sickle cell anemia and nonhemoglobinopathic adults

We cultured marrow and peripheral blood erythropoietic precrusors in methylcellulose clonal assay and measured the synthetic rates of HbA, A2, F, and S in patients with and without sickle cell anemia. Hb was labeled with 14C-amino acid in culture, separated by slab gel isoelectric focusing techniques, and quantitated by autoradiographic methods. Comparison of marrow late (CFU-E) and early (BFU-E) precursors from patients without hemoglobinopathies showed that preferential synthesis of HbF is limited to early precursors. Simultaneous examinations of Hb synthesis by blood and marrow early erythropoietic precursors confirmed the similarity of the biosynthetic capabilities of the precursors from the two sources. Increasing concentrations of erythropoietin (Ep) in culture corresponded with increases in the percentages of HbF synthesized by blood BFU-E of normal individuals. HbF biosynthesis by blood BFU-E from sickle cell anemia patients was significantly higher than that synthesized by nonanemic individuals and showed significant individual variations. HbF synthesis in patients with sickle cell anemia was partially dependent on Ep concentrations in culture. Cell culture of circulating erythropoietic precursors in man appears to provide a unique tool for studying the control mechanisms of Hb synthesis in man.

Synthesis of fetal and adult hemoglobins in culture by human umbilical cord blood erythropoietic precursors

We cultured human umbilical cord blood and adult peripheral blood erythropoietic precursors in methylcellulose clonal assay and measured the synthetic rates of HbA, A2, and F. Hb was labeled with 14C-amino acid in culture and separated by slab-gel isoelectric focusing and quantitated by autoradiography. While the mean percentage of HbF synthesized by adult cells was only 20.1%, that of umbilical cord blood cells was 53.9%, which corresponds closely to the biosynthetic capabilities of umbilical cord blood reticulocytes. Variations in the erythropoietin concentrations did not influence the percentage of HbF. Erythropoietic cell cultures of human umbilical cord blood may provide an important means for studying the molecular mechanisms controlling physiological Hb switching in the perinatal period.