Prevalence of -alpha(3.7) and alpha alpha alpha(anti3.7) alleles in sickle cell trait and beta-thalassemia patients in Mexico

The aim of this study was to determine the frequency of alpha-globin gene mutations in three groups of Mexican unrelated individuals. The first two groups were normal and sickle cell trait individuals from the Costa Chica region, a place with a 12.8% frequency of HbS carriers, and the third group comprised of Mexican mestizo patients with beta-thalassemia. We searched for -alpha(3.7) and -alpha(4.2) alpha(+)-thalassemia deletion alleles, as well as the alpha alpha alpha(anti3.7) triplication through long-gap PCR. The alleles -alpha(3.7) and alpha alpha alpha(anti3.7) were found in the heterozygote state only; 19% of the normal subjects had the -alpha(3.7) allele, and 2% showed the alpha alpha alpha(anti3.7) allele. In individuals with the sickle cell trait, 17% had the -alpha(3.7) deletion, and the alpha alpha alpha(anti3.7) triplication was observed in 3% of these individuals. We revealed that 16% of the subjects with beta-thalassemia showed the -alpha(3.7) deletion and 28% the alpha alpha alpha(anti3.7) triplication. The -alpha(4.2) deletion was not detected in any individual. The frequency of the -alpha(3.7) allele was roughly the same in the three groups studied; this can be explained by the fact that the three groups have common genes from Africa and the Mediterranean, where a high prevalence of alpha(+)-thalassemia has been observed. To our knowledge, the frequency of alpha alpha alpha(anti3.7) triplication observed in the Mexican beta-thalassemia patients is the highest reported. As the -alpha(3.7) and alpha alpha alpha(anti3.7) alleles are very common in our selected populations, we believe that there is a need to investigate systematically the alpha-globin gene mutations in all hemoglobinopathies in the Mexican population.     

An alpha0-thalassemia-like mutation: Hb Suan-Dok [alpha109(G16)Leu-->Arg] carried by a recombinant -alpha(3.7) gene

In a family of Spanish origin, five individuals presented a heterozygous alpha(0)-thalassemia (alpha-thal)-like phenotype. All had a -alpha(3.7) deletion with the recombinant alpha gene carrying the Hb Suan-Dok [alpha109(G16)LeuArg] mutation, proposed to be thalassemic. Thus, the abnormal chromosome carried an alpha(0)-thal-like allele that has to be taken into account for genetic counseling and prenatal diagnosis. The possibility of Hb H disease or hydrops fetalis should be considered when this allele is associated with alpha(+)-thal or with another alpha(0)-thal, respectively. Other described genotypes associated with Hb Suan-Dok are discussed.     

Dinucleotide deletion in -alpha3.7 allele causes a severe form of alpha+ thalassaemia

We describe a family of Italian origin in which the father and his two children had hypochromia and microcytosis with normal iron status. All individuals underwent an uneventful clinical course and required no treatment. To investigate the molecular basis of this phenotype, which is a prerequisite for further genetic counselling, we revealed that all affected family members are carriers of a common form of alpha+ thalassaemia resulting from the deletion of 3.7 kb of the alpha-globin cluster (alphaalpha/-alpha3.7). However, this genotype alone could not account for the phenotype presenting in this family. Further characterization of the alpha-globin genes demonstrated an additional AC deletion in the vicinity of the initiation codon of the -alpha3.7 allele. This secondary mutation causes an additional impaired translation of the affected allele producing increased globin chain imbalance. This leads to a more severe phenotype, as heterozygotes for such mutation (alphaalpha/-alphaT) have hypochromic microcytosis and abnormal globin chain synthesis that mimic alpha0 thalassaemia trait (--/alphaalpha). Accurate genotyping of alpha globin determinant is absolutely required as there is a possibility that an interaction of this unusual double mutation with other common alpha0 thalassaemias (--/-alphaT) can give rise to a very severe, probably fatal, alpha thalassaemia.     

Crystal structure of oxygen-evolving photosystem II from Thermosynechococcus vulcanus at 3.7-A resolution

Photosystem II (PSII) is a multisubunit membrane protein complex performing light-induced electron transfer and water-splitting reactions, leading to the formation of molecular oxygen. The first crystal structure of PSII from a thermophilic cyanobacterium Thermosynechococcus elongatus was reported recently [Zouni, A., Witt, H. T., Kern, J., Fromme, P., Krauss, N., Saenger, W. & Orth, P. (2001) Nature 409, 739-743)] at 3.8-A resolution. To analyze the PSII structure in more detail, we have obtained the crystal structure of PSII from another thermophilic cyanobacterium, Thermosynechococcus vulcanus, at 3.7-A resolution. The present structure was built on the basis of the sequences of PSII large subunits D1, D2, CP47, and CP43; extrinsic 33- and 12-kDa proteins and cytochrome c550; and several low molecular mass subunits, among which the structure of the 12-kDa protein was not reported previously. This yielded much information concerning the molecular interactions within this large protein complex. We also show the arrangement of chlorophylls and cofactors, including two beta-carotenes recently identified in a region close to the reaction center, which provided important clues to the secondary electron transfer pathways around the reaction center. Furthermore, possible ligands for the Mn-cluster were determined. In particular, the C terminus of D1 polypeptide was shown to be connected to the Mn cluster directly. The structural information obtained here provides important insights into the mechanism of PSII reactions.     

Pion spectrum in decay of Psi'(3.7) to Psi(3.1)

The decay of Ψ′ → Ψ + ππ is described by a chiral ε model. The general features of the observed dipion spectrum are well reproduced. Comparison with the hadronic decay ρ′ → ρ + ππ indicates that the Ψ′Ψε coupling is relatively suppressed by a factor ~10^-2.     

A moderately severe alpha-thalassemia condition resulting from a combination of the alpha2 polyadenylation signal (AATAAA-->AATA- -) mutation and a 3.7 Kb alpha gene deletion in an Australian family

We have recently studied a family with a rare combination of two abnormal alpha-globin genes. The combination of a two-base (AA) deletion in the alpha2 polyadenylation signal (poly A) (AATAAA-->AATA- -) and a 3.7 kb alpha gene deletion, found in two children, resulted in a moderately severe thalassemic condition. Both parents and three siblings were tested and the hematological condition and molecular findings are presented. The father was born in India with Portuguese and British ancestry; the mother is of Dutch ancestry. All three siblings were born in Australia.     

Spectrin Oran (alpha II/21), a new spectrin variant concerning the alpha II domain and causing severe elliptocytosis in the homozygous state

We report on spectrin Oran (alpha II/21), a new spectrin variant found in an Algerian family. It was characterized by the absence of the spots that classically correspond to the alpha II domain using two-dimensional analysis of spectrin limit digests. On the contrary, the abnormal domain was represented by a new set of spots in the 21-Kd and 16-Kd regions, as demonstrated by Western blots using anti-alpha II domain polyclonal antibodies. Spectrin Oran (alpha II/21) was found in the homozygous state in two children belonging to two separate branches of the family. It yields a severe elliptocytosis. Spectrin self-association was altered. The variant was much more difficult to prove in the heterozygous state, in which it results in no clinical and virtually no morphological symptom. In all four parents involved, however, electrophoretic analysis and Western blots showed the existence of the alpha II 21-Kd and 16-Kd peptides. In one parent, who combines spectrin Oran (alpha II/21) and the alpha II type-2 polymorphism, the two-dimensional spots (52, 39, 34, and 29 Kd) were quantified and appeared reduced by 30%: there was an intermediary decrease of spectrin self-association in this person. In the three other parents, spectrin Oran combined with the alpha II type-1 polymorphism. The alpha II type-1 spots (46, 35, 30, and 25 Kd) appeared in normal range, and spectrin self-association was normal. Along with previous observations, the present data emphasize the large fluctuations of the alpha-variant percentage. Provided spectrin Oran was present in a sufficient proportion, we found an associated alteration of the beta II domain (that faces the alpha II domain in the spectrin dimer): the beta II 65-Kd fragment was reduced and the beta II 52-Kd fragment was reciprocally increased.     

Angiotensin II and alpha(v)beta(3) integrin expression in rat neonatal cardiac fibroblasts

We recently demonstrated that alpha(v)beta(3) integrins are involved in the mechanisms of angiotensin II (Ang II)-induced DNA synthesis and collagen gel contractions in rat cardiac fibroblasts (CFBs), cellular mechanisms that are relevant for cardiac remodeling. The aim of the present study was to elucidate the effect of Ang II and other growth factors on the regulation of the alpha(v)beta(3) integrins in fibroblasts from neonatal rat hearts. The alpha(v)beta(3) integrin receptor expression was significantly increased (P<0.05) at the mRNA level after treatment with Ang II, transforming growth factor-beta(1) (TGF-beta(1)), and platelet-derived growth factor (PDGF) for 8 and 16 hours. The surface expression of the alpha(v) and beta(3) integrin subunits was elevated after 32 and 48 hours (P<0.05) as determined with flow cytometry. To investigate fibroblast motility, we performed chemotaxis experiments with transwell chambers. Ang II was chemotactic for CFBs, as tested with checkerboard experiments. The chemotactic effect was concentration dependent and was completely blocked by Ang II type 1 receptor blockers but not by Ang II type 2 receptor blocker PD 123319. Ang II- and PDGF-BB-mediated chemotaxis could be significantly inhibited by RGD peptides and the blocking antibodies against alpha(v)beta(3) integrin (both P<0.01). Adhesion of CFBs to vitronectin was partially inhibited by an antibody to alpha(v)beta(3) integrin but was mainly mediated by an alpha(v)beta(5) integrin. Relevant in vivo expression of alpha(v)beta(3) integrin by CFBs was confirmed with in situ hybridization with probes for alpha(v) and beta(3) mRNA in rat hearts. The present study demonstrates that the expression of alpha(v)beta(3) integrin is augmented by Ang II, PDGF, and TGF-beta(1) in neonatal CFBs. Furthermore, this integrin is involved in the chemotaxis, motility, and adhesion of CFBs. The present findings support the current concept that integrins participate in the control of fibroblast behavior during cardiac remodeling mechanisms.     

急性冠脉综合征患者抗Ⅹa因子、抗Ⅱa因子的变化及低分子质量肝素的干预作用

目的观察急性冠脉综合征(ACS)患者抗Ⅹa因子、抗Ⅱa因子的变化及低分子肝素(LMWH)的干预作用。方法将上海交通大学附属第一医院2003-01~2003-09收治的24例ACS患者和10例正常人(作对照)纳入研究对象。采用发色底物法测定血浆中的抗Ⅹa因子、抗Ⅱa因子。ACS患者用LMWH抗凝治疗并分别于入院即刻,LMWH注射后4h、注射后24h、注射7d后观察抗Ⅹa因子和抗Ⅱa因子的变化。结果(1)ACS患者血浆抗Ⅹa因子和抗Ⅱa因子明显高于正常者(P<0·01)。(2)抗Ⅹa因子在LMWH注射后4h、24h、7d较注射前明显增加(P<0·01),注射后4h达高峰,以后逐渐下降;抗Ⅱa因子在LMWH注射后4h、24h、7d较注射前明显增加(P<0·01),在注射后24h达高峰。结论ACS患者血浆抗Ⅹa因子升高与ACS的发病机制及LMWH的干预作用有关。LMWH对Ⅹa因子的作用较Ⅱa因子强,且达峰时间短。     

Exclusion of the alpha 1(II) collagen structural gene as the mutant locus in type II Ehlers-Danlos syndrome.

We have used a high frequency site polymorphism within the human pro-alpha 1(II) collagen gene (COL2A1) in order to examine the segregation of this gene within a large pedigree with type II Ehlers-Danlos syndrome (EDS). The EDS gene and the collagen gene segregate independently within the pedigree and therefore COL2A1 can be excluded as the mutant locus.     

Erythrocyte membrane proteins reactive with IgG (warm-reacting) anti- red blood cell autoantibodies: II. Antibodies coprecipitating band 3 and glycophorin A

In our initial immunochemical study of the red blood cell (RBC) membrane proteins targeted in 20 cases of warm-antibody autoimmune hemolytic anemia (AHA), RBC eluates of 6 patients mediated immunoprecipitation (IP) of both band 3 and glycophorin A (GPA). This dual IP pattern had previously been observed with murine monoclonal antibodies (MoAbs) against the high frequency blood group antigen, Wrb (Wright), suggesting that the Wrb epitope may depend on a band 3-GPA interaction. Earlier, anti-Wrb had been identified serologically as a prominent non-Rh specificity of AHA autoantibodies. In the present study, 6 autoantibody eluates immunoprecipitating band 3 and GPA from common Wr(b+) RBCs were retested, in parallel with murine anti-Wrb MoAbs, against very rare Wr(a+b-)En(a+)RBCs. One patient's autoantibodies were unreactive with the Wr(b-) RBCs by either IP or indirect antiglobulin test (IAT) and were judged to have "pure" anti- Wrb specificity. Two other patients' autoantibodies displayed both IP and serologic evidence for anti-Wrb as a major component in combination with one or more additional specificities. However, among 3 other patients whose autoantibodies coprecipitated band 3 and GPA, there was no reduction in IP or IAT reactivity with Wr(b-) RBCs in 2 and only slight reduction in the third. We conclude (1) that human anti-Wrb autoantibodies, like their murine monoclonal counterparts, coprecipitate band 3 and GPA from human RBCs; but (2) that not all antibodies with this IP behavior have anti-Wrb serologic specificity, as defined by this donor's Wr(b-) RBCs. The possibility of an additional (non-Wrb) RBC epitope dependent on a band 3-GPA interaction is raised.