jeanflop/post-ocr-correction huggingface dataset:
α-thalassemic gene and/or when they have been splenectomized. These hemoglobins are often referred to as non-deletional α-thalassemias [1-6]. The different hemoglobin variants that may be classified in this group are reported in Table III. Some of them lead 44U C. R. Acad. Sci. Paris, Sciences de la vie/Life sciences, 1994; 317 : 437-44 Hb Taybe: an α-globin defect Figure 4. Direct genomic sequencing of an α1-gene segment of a normal subject (lane 1) and the propositus (lane 2), showing a bp deletion corresponding to a threonine residue in the α1-globin gene. Figure 5. Analysis of Pa03-C2 α1-globin gene fragments from
gene. Figure 5. Analysis of Pa03-C2 α1-globin gene fragments from normal individuals (lane 1,2), the index case (lane 3) and her parents (lanes 4,5). M: the size marker marker was cut with Hae III. H=homoduplex molecules. h=heteroduplex molecules. Their α1-specificity was checked by Apa I digestion analysis. Hb Quong Sze [α125(H8)Leu→Pro] found in a Chinese patient with a Hb H phenotype and carrying a [--/α1QS] genotype, was the first abnormal hemoglobin of this group described. The sequence of the α2 gene showed that codon 125 was CCG (Pro) instead of CTG (Leu). During biosynthesis studies, the abnormal gene was shown
CTG (Leu). During biosynthesis studies, the abnormal gene was shown to be transcribed normally but the extremely rapid degradation of the abnormal chain resulted in a functional loss of the mutated α2 gene. Simple heterozygotes for Hb Quong Sze [α1/α2QS] resembled α-thalassemia carriers: there was no evidence of hemolysis nor Heinz bodies. The mutant chain, thus, did not lead to an unstable hemoglobin syndrome but, surprisingly, to an α-thalassemia trait phenotype. This disorder was explained at the molecular level by an alteration of the α1 contact area, resulting in free uncombined α- and β-globin chains and perhaps in an instability
uncombined α- and β-globin chains and perhaps in an instability of transiently assembled tetramers [14-16]. In some patients a dominant Heinz bodies hemolytic hereditary anemia overlaps the α-thalassemic syndrome. Hemoglobin Petah Tikva [α110(G17)Leu→Asp], described in Israel among Iraqi Jews, is an unstable variant that yields the phenotype of a mild Hb H disease when present in combination with α-thalassemia trait [8]. In patients having Hb Petah Tikva in association with α-thalassemia the globin chain synthesis ratio was that expected for a mild Hb H disease. Conversely, the carriers of Hb Petah Tikva without associated α-thalassemia were clinically normal. In this
Petah Tikva without associated α-thalassemia were clinically normal. In this case, no Hb H was observed but a substantial excess of total α-chain synthesis relative to β-chain synthesis was found. Such a paradoxical biosynthetic ratio has been C. R. Acad. Sci. Paris, Sciences de la vie/Life sciences, 1994; 317 : 437-44 F. Gaiti et al. Table III Unstable hemoglobin variants responsible for "non deletional α-thalassemias" Variant Structural modification Gene HbH % Référence Hb Evanston α1 (A12) Trp → Arg rightward α-thal2 traces 19 Hb Agrinion α29 (B10) Leu → Pro cc2 traces 25 Hb Taybe α38 or 39 (C4) Thr
cc2 traces 25 Hb Taybe α38 or 39 (C4) Thr → al 0.5** (this paper) Hb Adana α59 (G11) Gly → Asp α1 traces*** 21 Hb Sallanches α104 (E8) Cys → Tyr α <2** 20 Hb Suang Dok α109 (G16) Leu → Arg α2 15*** 23 Hb Petah Tikva α110 (G17) Leu → Asp ? 3*** 8 Hb Quong Sze α125 (H8) Leu → Pro α2 35*** 15 * Compound heterozygote for α-thal2. ** Homozygotes. *** Compound heterozygote for α-thal. observed in several unstable α-chain variants present in the heterozygous state. In Hb Petah Tikva, the modified residue also participates
state. In Hb Petah Tikva, the modified residue also participates in the α2 subunit contact. In the case of Hb Evanston, the thalassemia-like expression resulted from two separate mechanisms: the instability of the abnormal α-chain and the presence of this mutation in the single gene of a rightward deletion α-thalassemia-2 chromosome. In the heterozygous carriers of Hb Taybe, in contrast with Hb Quong Sze, no hematological abnormalities were found. This situation is similar to that reported for Hb Sallanches in which the heterozygous carriers were asymptomatic and the abnormal Hb only detected in the homozygous patient. The genetic abnormality of
only detected in the homozygous patient. The genetic abnormality of Hb Taybe concerns an α gene whereas, in the other variants reported in Table III, with the exception of Hb Adana, the α2 gene is affected. The α globin gene is less transcribed than the α2 gene and a mutation of this gene is usually without hematological consequences. This is illustrated by the hematological status of the parents, who are heterozygous carriers of the abnormal Hb. The three siblings, which are homozygous, are suffering from a more or less severe hemolytic anemia as a result of a threshold effect of
hemolytic anemia as a result of a threshold effect of the molecular abnormality. Homozygous cases of such rare hemoglobin variants may not be exceptional in populations in which the degree of consanguinity is relatively high due to geographical and sociological constraints. The structural abnormality of Hb Taybe is localized in helix C, which is a highly conserved α helix participating in the α2 contact. In the same region of the molecule, the insertion of a glutamate has been described in Hb Catonsville (Pro37α-Glu-Thr38α) : the resulting hemoglobin was moderately unstable and responsible for an increased oxygen affinity. In Hb Catonsville,
and responsible for an increased oxygen affinity. In Hb Catonsville, X-ray diffraction studies demonstrated that the insertion-induced perturbation of the structure conforms with the "bulge" model that interconverts different types of protein helices. Helix C became an α-helix and the remaining of the contact area was not disturbed. The high degree of instability of Hb Taybe suggests that the deletion of one residue in this helix may rather lead to a "register shift" inducing series of "effective mutations". This may modify the BC corner and the end of helix B, which is involved in the α2 contact (Fig. 6). We
which is involved in the α2 contact (Fig. 6). We had recently the opportunity to study another very unstable variant, Hb Hirosaki [α43(CE1)Phe → Leu], that we found to be also encoded by an α gene. This hemoglobin displays a structural modification within the heme pocket and results in the formation of very unstable oxidized tetramers. The heterozygous carrier was, in this case, suffering from a severe hemolytic anemia with Heinz bodies and without Hb H. Therefore, it is likely that the structural modification of Hb Taybe brings about a very unstable dimer that, in turn, dissociates into monomers. In
very unstable dimer that, in turn, dissociates into monomers. In the heterozygous carrier, these free chains are proteolyzed and the phenotype became then somewhat similar to an α-thal 2. In the homozygotes, it is likely that the amount of abnormal hemoglobin exceeds the proteolytic possibility of the cell and, thus, gives rise to the hemolytic syndrome. Due to an increased instability of the abnormal α-chains, a small amount of free β-chains remains in solution, thus, leading to their association in Hb H. This situation may be compared to that of many unstable variants of the β-chains in which small amounts
many unstable variants of the β-chains in which small amounts of free α-chains are frequently detected and is different from a true Hb H disease with marked unbalanced α/β chain biosynthetic ratio and microcytosis. When associated to another α-thalassemic gene, these variants may behave like a true α-thal 2 gene resulting in the presence of significant amounts of Hb H. As shown in Table III, values up to 15 % have been reported for Hb Suan Dok. VERSION ABRÉGÉE Les hémoglobines instables affectant la chaîne α ont des modalités d'expression clinique et biologique différentes de celles portées par la chaîne
clinique et biologique différentes de celles portées par la chaîne β. Les variants α sont le plus souvent cliniquement silencieux chez les sujets hétérozygotes alors que les hémoglobines instables situées sur la chaîne β réalisent une maladie cliniquement dominante. Ces variants peuvent même totalement échapper aux méthodes biochimiques de détection dans le sang périphérique. À l'inverse, chez les porteurs homozygotes de la mutation, ou chez les sujets hétérozygotes composites pour un gène α-thalassémique, ces hémoglobines réalisent un tableau d'anémie hémolytique sévère avec quelquefois présence d'Hb H. L'hémoglobine anormale peut quant à elle n'être décelable qu'après splénectomie. À des signes biologiques
à elle n'être décelable qu'après splénectomie. À des signes biologiques d'anémie hémolytique s'ajoutent donc apparemment des signes d'α-thalassémie. Nous décrivons ici l'Hb Taybe où s'observe une telle situation. Cette hémoglobine a été identifiée dans une famille Arabe israélienne, chez une jeune femme de 22 ans souffrant depuis son enfance d'une anémie hémolytique sévère et pour laquelle aucun diagnostic étiologique n'a pu être porté à l'époque. À la suite d'une aggravation des poussées hémolytiques, la patiente a été splénectomisée à l'âge de 16 ans. Devant la persistance des troubles (Tableau I) l'étude hématologique a été reprise lors d'un séjour de la
l'étude hématologique a été reprise lors d'un séjour de la patiente à Paris. La focalisation isoélectrique de l'hémoglobine a montré un constituant anormal représentant environ 3 % de l'hémolysat total migrant entre l'HbA et l'HbF. Ce constituant a été isolé par une technique miniaturisée de focalisation isoélectrique préparative et l'anomalie structurale a été caractérisée en utilisant les méthodes de la chimie des protéines. Le profil d'élution en chromatographie liquide haute performance des peptides obtenus après hydrolyse de la chaîne anormale (Fig. 3) montre un pic d'élution retardée dont la composition en acide aminé suggère la délétion d'un résidu de threonine
en acide aminé suggère la délétion d'un résidu de threonine en position a38 ou 39. L'étude de l'ADN de la patiente (Fig. 1, 4 et 5) localise cette délétion sur le gène α de globine et nous révèle qu'elle est homozygote pour l'anomalie. L'étude de l'ADN des divers membres de la famille confirme l'hétérozygotie pour l'Hb Taybe des deux parents qui sont cousins. Elle montre que le frère et la soeur de la malade, eux-mêmes anémiques et ayant de l'Hb H sont homozygotes (Fig. 2). L'anomalie structurale est donc localisée dans l'hélice C, caractérisée à travers toute la série des
dans l'hélice C, caractérisée à travers toute la série des globines par un pas de périodicité 3,10. Cette région est à la fois proche de l'interface α1 π qui assure la cohésion de la molécule d'hémoglobine et participe à l'interface α2 où s'effectue l'essentiel des mouvements accompagnant la transition entre structures oxygénée et désoxygénée (Fig. 6). Cette hémoglobine instable démontre l'existence d'un seuil critique dans les manifestations cliniques et hématologiques du gène anormal : l'expression d'un seul gène anormal est parfaitement tolérée, voire muette, celle de deux gènes anormaux est à l'origine d'une anémie sévère. Chez l'hétérozygote, le constituant hémoglobinique
à l'origine d'une anémie sévère. Chez l'hétérozygote, le constituant hémoglobinique anormal est sans doute totalement protéolysé et comme dans une α+-thalassémie hétérozygote les signes cliniques et hématologiques sont pratiquement absents. Par contre chez l'homozygote les signes cliniques et hématologiques sont ceux d'une anémie hémolytique à corps de Heinz ayant toutefois la particularité de s'accompagner de traces d'Hb H. Cette dernière ne témoigne sans doute pas d'un déficit de synthèse en chaînes α comme dans les α-thalassémies mais d'un excès en chaînes β résultant d'un défaut dans les mécanismes d'association en tétramères et d'une précipitation sélective de la chaîne α. C.
tétramères et d'une précipitation sélective de la chaîne α. C. R. Acad. Sci. Paris, Sciences de la vie/Life sciences, 1994; 317: 437-44 443 F. Gajácheros et al. REFERENCES 1. Steinberg M. H., Adams J. G. 1983. Thalassemic hemoglobinopathies. Am. J. Pathol. 113: 396, 1983. 2. Adams J. G. III., Coleman M. B. 1990. Structural hemoglobin variants that produce the phenotype of thalassemia. Semin. Hematol. 27: 229. 3. Ohba Y. 1990. Unstable hemoglobins. Hemoglobin 14: 353. 4. Thein S. L, Hesketh C, Taylor P., Temperley I. J., Hutchinson R. M., Old J. M., Wood W. G., Clegg J. B. 1990. Molecular
J. M., Wood W. G., Clegg J. B. 1990. Molecular basis for dominantly inherited inclusion body β-thalassemia. Proc. Natl. Acad. Sci. USA 87: 3924. 5. Thein S. L. 1992. Dominant β-thalassemia: molecular basis and pathophysiology. Br. J. Haematol. 80: 273. 6. Stamatoyannopoulos G., Woodson R., Papayannopoulou T., Heywood D., Kurachi M. S. 1974. Inclusion-body β-thalassemia trait: A form of β-thalassemia producing clinical manifestations in simple heterozygotes. N. Engl. J. Med. 290: 939. 7. Kazazian H. H., Dowling C. E., Hurwitz R. L, Coleman M., Stopeck A., Adams J. G. III. 1992. Dominant thalassemia-like phenotypes associated with mutations in exon 3
1992. Dominant thalassemia-like phenotypes associated with mutations in exon 3 of the β-globin gene. Blood 79: 3014. 8. Honig G. R., Shamsuddin M., Zaizov R., Steinherz M., Solar I., Kirschmann C. 1981. Hemoglobin Petah Tikva (α 10 Ala—>Asp): a new unstable variant with α-thalassemia-like expression. Blood 57: 705. 9. Wajcman H., Bardakdjian J., Ducrocq R. 1993. Structural characterization of abnormal hemoglobins from dried blood specimens in a neonatal screening program. Ann. Biol. Clin. 51: 867. 10. Dodé C, Rochette J., Krishnamoorthy R. 1990. Locus assignment of human α-globin mutations by selective amplification and direct sequencing. Br. J. Haematol. 76: 275.
selective amplification and direct sequencing. Br. J. Haematol. 76: 275. 11. Maniatis T., Fritsch E. F., Sambrook J. 1982. Molecular cloning: a laboratory manual. New York: Cold spring Harbor Laboratory. 12. Attree O., Vidaud D., Vidaud M., Amselem S., Lavergne J. M., Goossens A. A. 1989. Mutations in the catalytic domain of human coagulation factor IX: rapid characterization by direct genomic sequencing of DNA fragments displaying an altered melting behavior. Genomics 4: 266. 13. Feinberg A. P., Vogelstein B. 1983. A technique for radiolabelling DNA restriction endonuclease fragments to high specific activity. Anal. Biochem. 132: 6. 14. Kan Y. W.,
specific activity. Anal. Biochem. 132: 6. 14. Kan Y. W., Dozy A. M., Trecartin R., Todd D. 1977. Identification of a non-deletion defect in α-thalassemia. N. Engl. J. Med. 297: 1081. 15. Goossens M., Lee K. Y., Liebhaber S. A., Kan Y. W. 1981. Globin structural mutant α 25 Leu --> Pro is a novel cause of α-thalassemia. Nature 296: 864. 16. Liebhaber S. A., Kan Y. W. 1983. α-Thalassemia caused by an unstable α-globin mutant. J. Clin. Invest. 71: 461. 17. Adams J. G. III., Winter W. P., Rucknagel D. L, Spencer H. H. 1972. Biosynthesis of hemoglobin Ann
D. L, Spencer H. H. 1972. Biosynthesis of hemoglobin Ann Arbor: evidence for catabolic and feedback regulation. Science 176: 1427. 18. Wajcman H., Vasseur C, Blouquit Y., Rosa J., Labie D., Najman A., Reman O., Leporrier M., Gajácheros F. 1993. Unstable α-chain hemoglobin variants with factitious β-thalassemia biosynthesis ratio: Hb Questembert (α 31[H14] Ser --> Pro) and Hb Caen (α 32[H15] Val --> Gly). Am. J. Hematol. 42: 367. 19. Honig G. R., Shamsuddin M., Vida L. N., Mompoint M., Valcourt E., Bowie L. J., Jones E. C, Powers P. A., Spritz R. A., Guis M., Embury S. H., Conboy
A., Spritz R. A., Guis M., Embury S. H., Conboy J., Kan Y. W., Mentzer W. C, Weiss S. C, Hirata R. K., Waloch J., O'Riordan J. F., Goldstick T. K. 1984. Hb Evanston (α 4 Trp --> Arg) An unstable α-chain variant expressed as α-thalassemia. J. Clin. Invest. 73: 1740. 20. Morlé F., Francina A., Philippe N., Souillet G., Godet J. 1993. Hb Sallanches, a new α-chain variant [α 104(G11) Cys --> Tyr] associated with Hb H disease in one homozygous patient. Club de l'Hémoglobine, Strasbourg (abstr.). 21. Curiuk M. A., Dimovski A. J., Baysal E. Gu L. H.,
M. A., Dimovski A. J., Baysal E. Gu L. H., Kutlar F., Molchanova T. P., Webber B. B., Altay C, Gurgey A., Huisman T. H. J. 1993. Hb Adana or α259(E8) Gly → Asp, a severely unstable α-globin variant, observed in combination with the (-a)20.5 kb α-thal-1 deletion in two Turkish patients. Am. J. Hematol. 44: 270. Kavanaugh J. S., Moo-Penn W. F., Arnone A. 1993. Accommodation of insertions in helices: the mutation in hemoglobin Catonsville (Pro 37a-Glu-Thr 38a) generates a 3-nucleotide bulge. Biochemistry 32: 2509. Ohba Y., Miyaji T., Matsuoka M., Yoko Yama M., Numakura H., Nagata K., Takebe
Matsuoka M., Yoko Yama M., Numakura H., Nagata K., Takebe Y., Izumi Y., Shibata S. 1975. Hemoglobin Hirosaki (α43[CE1] Phe → Leu), a new unstable variant. Biochim. Biophys. Acta 405: 155. Weiss L, Cash F. E., Coleman M. B., Pressley A., Adams J. G., Sanguansermsri T., Liebhaber S. A., Steinberg M. H. 1990. Molecular basis for α-thalassemia associated with the structural mutant hemoglobin Suan-Dok (α2109Leu → Arg). Blood 76: 2630. Hall G. W., Thein S. L., Newland A. C, Chisholm M., Traeger-Synodinos J., Higgs D. R. 1993. A novel mutation (T-C) in codon 29 of the α2 globin gene produces
(T-C) in codon 29 of the α2 globin gene produces a structural haemoglobin variant and α-thalassemia. Br. J. Haematol. 84 (suppl. 1): 63 (abstr. P153). C. R. Acad. Sci. Paris, Sciences de la vie/Life sciences, 1994; 317 : 437-44 C. R. Acad. Sci. Paris, Sciences de la vie/Life sciences, 1994; 317 : 445-51 Sciences médicales/Médical sciences Do microglial cells phagocyte the β/A4-amyloid sénile plaque core of Alzheimer disease? Les cellules microgliales phagocytent-elles la substance β/A4 amyloïde du cœur de la plaque sénile de la maladie d'Alzheimer? KHALID HAMID EL HACHIMI, JEAN-FRANÇOIS FONCIN EPHE Neurohistologie and INSERM U. 106, Hôpital de
JEAN-FRANÇOIS FONCIN EPHE Neurohistologie and INSERM U. 106, Hôpital de la Salpêtrière, 47, boulevard de l'Hôpital 75651 Paris Cedex 13, France. Tirés à part : K. H. El Hachimi RÉSUMÉ Nous avons étudié à l'échelle ultrastructurale, immuno-ultrastructurale et immuno-photonique la relation topographique et fonctionnelle entre les cellules microgliales et les plaques séniles de la maladie d'Alzheimer. Nos résultats montrent que ces cellules, présentant les caractéristiques cytologiques de la phagocytose, sont associées aux dépôts amyloïdes classiques ainsi qu'aux autres lésions neurodégénératives. En périphérie du cœur amyloïde, ces cellules contiennent des amas fibrillaires immunoréactifs à anti-β/A4 amyloïde et entourés d'une membrane. Les
fibrillaires immunoréactifs à anti-β/A4 amyloïde et entourés d'une membrane. Les dépôts préamyloïdes des couches superficielles, essentiellement de la couche II, ne sont pas associés aux cellules microgliales. Les caractéristiques cytologiques de ces cellules, le caractère uniquement fibrillaire du matériel immunoréactif et l'absence d'immunoréactivité sur matériel amorphe ou dans les organites de sécrétion, dans ces cellules aussi bien que dans les cellules non associées aux plaques, sont en faveur d'une activité phagocytaire de la microglie vis-à-vis de l'amyloïde dans la maladie d'Alzheimer. ▲ Mots clés : cellules microgliales, maladie d'Alzheimer. ABSTRACT We performed EM, immuno-EM and light microscope immunohistochemistry studies on
We performed EM, immuno-EM and light microscope immunohistochemistry studies on the topography and functional relationships between microglial cells and amyloid sénile plaque core in Alzheimer's disease. Microglial cells with cytological characteristics of phagocytic function were associated to amyloid fibrils and to other neuropathological degenerative processes. On the periphery of the amyloid plaque core, microglial cells contain intracytoplasmic bundles of membrane bound fibrils. These fibrils, like plaque core fibrils, are immunodecorated. Immunostaining was observed neither in secretory organelles nor in hyaloplasm. Preamyloid deposits in superficial layers were not associated to microglial cells. These data lead us to conclude that the microglial
cells. These data lead us to conclude that the microglial cells participate to phagocytosis of β/A4 amyloid and do not secrete this substance in Alzheimer's disease. ▲ Key words : microglial cells, Alzheimer disease. Voir Version abrégée (p. 450) The generic term of amyloid covers a group of diverse proteins with spécifique conformational (β-pleated sheet) and staining (Congo red and thioflavine) characteristics. Human cerebral amyloidoses include Alzheimer's disease, cerebral amyloid angiopathies and transmissible spongiform encephalopathies (Kuru, Creutzfeldt-Jakob and Gerstmann-Straußler-Scheinker diseases). In Alzheimer's disease, a major constituent of the amyloid is a 4 kD peptide, β/A4 amyloid protein, BAP [1, 2]
a 4 kD peptide, β/A4 amyloid protein, BAP [1, 2] which derives from a larger glycoprotein called amyloid precursor protein, APP [3]. APP has been shown to be présent in various cells, including neurons, astrocytes and in extracellular fluid [4]. How BAP derives from APP is still unknown; one of the unanswered questions in Alzheimer's disease research is the relationship between neuronal degeneration and amyloid deposits. Several studies reported that degenerated neurons and dystrophic neurites associated with plaques accumulate various fragments of APP and suggested that neuronal APP is the most likely initial source of extracellular BAP [5]. Neuritic plaques
most likely initial source of extracellular BAP [5]. Neuritic plaques are composed mainly of amyloid fibrils, degenerating neurites, and reactive cells such as astrocytes and microglial cells. More recently, antibodies directed against various fragments of the β/A4 peptide have enabled to recognize, besides the amyloid core of classical plaques and the vascular amyloid deposits, another type of deposit that displays neither the ultrastructural fibrillary morphology nor the tinctorial characteristics of amyloid. These deposits have been called diffuse plaques [6] or preamyloid deposits [7]. The relationship with amyloid sensu stricto remains obscure. We correlated previously the amorphous amyloid of diffuse deposits
obscure. We correlated previously the amorphous amyloid of diffuse deposits with the dégénérescence of dendritic spines, whereas degenerating neurites were not immunostained [8, 9]; these studies however, had no bearing on the origin of the fibrillar amyloid of the classical plaque core. Among the cells associated with sénile plaques, microglial cells have been proposed as playing an important rôle in the formation of sénile plaques [10]. Microglial cells are activated by inflammatory, degenerative or traumatic events in the nervous System. They migrate to the site of injury and are transformed into activated macrophages filled with vacuoles and lipid droplets. Microglial
into activated macrophages filled with vacuoles and lipid droplets. Microglial cells are also known to secrete various proteins including glial growth factors, and interleukin 1 (for review see [11]). Ferritin is considered an sélective marker of these cells [12]. The présent study was designed to examine the topography and functional relationships between microglial cells and sénile plaques in order to specify whether they phagocyte or secrete β/A4 amyloid. This problem was addressed by means of conventional electron microscopy, immunoelectron microscopy study of anti-amyloid in biopsy specimens, and light microscopy double immunostaining of Alzheimer-amyloid deposits (anti-amyloid) and microglial cells (anti-human L-ferritin)