Structure and expression of the ATFa gene

The human ATFa proteins belong to the ATF/CREB family of transcription factors. We have previously shown that they mediate the transcriptional activation by the largest E1a protein and can heterodimerize with members of the Jun/Fos family. ATFa proteins have also been found tightly associated with JNK2, a stress-activated kinase. We now report on the structure of the ATFa gene, which mapped to chromosome 12 (band 12q13). Sequence analysis revealed that ATFa isoforms are generated by alternative splice donor site usage. A minimal promoter region of approximately 200 base pairs was identified that retained nearly full transcriptional activity. Binding sites for potential transcription factors were delineated within a GC-rich segment by DNase I footprinting. Expression studies revealed that ATFa accumulates in the nuclei of transfected cells, and the nuclear localization signal was defined next to the leucine zipper domain. As revealed by hybridization with mouse ATFa sequences, low levels of ATFa mRNAs were ubiquitously distributed in fetal or adult mice, with enhanced expression in particular tissues, like squamous epithelia and specific brain cell layers. The possible significance of coexpression of ATFa, ATF-2, and Jun at similar sites in the brain is discussed.

In vivo association of ATFa with JNK/SAP kinase activities

The human ATFa proteins belong to the CREB/ATF family of transcription factors. We have previously shown that the ATFa proteins may contribute to the modulation of the transcriptional activity of the Jun/Fos complexes (Chatton et al. (1994). Oncogene, 9, 375-385). We now show that a protein kinase activity is strongly associated with ATFa in vivo, as revealed by coimmunoprecipitation of ATFa/kinase complexes from whole cell extracts, with antibodies against ATFa. Two independent regions were found to be implicated in kinase binding: a major interaction site is located within the N-terminal 82 residues comprising an important metal-chelating element; a weaker binding site corresponds to the basic sequence element preceding the C-terminal leucine-zipper of ATFa. Induction experiments suggest that each of these ATFa domains may interact with different kinases. The major activity is associated with the ATFa N-terminal domain. Based on its response to various inducers, on both in vitro and in vivo binding assays, and on its immunological properties, this activity most likely corresponds to the 54/55 kDa JNK2 protein. Taken together, these observations suggest that the ATFa proteins, among other CREB/ATF proteins, may be important effectors of cell signalling pathways.

[Diplopia as a complication after surgery for strabismus in adolescents and adults]

Diplopia may occur following surgery for the correction of constant manifest strabismus. Young children rarely complain of diplopia because of the plasticity of their visual system and the rapid development of suppression. However, in older children and adults post-operative diplopia may occur either as a transient well-tolerated phenomenon or occasionally as an intractable problem. It is a standard practice to carry out tests prior to surgery to try and predict the risk of post-operative diplopia, although the value of these tests and the incidence and severity of diplopia following squint surgery is not well documented. We reviewed the records of these 22 out of all our patients operated for squint who had diplopia (aged 13-45). 13 subjects presented diplopia only for 1 or 2 days after surgery 8 had intermittent one with good tolerance and 1 acquired constant diplopia (she was operated). Pre- and post-operative agents which could have had an impact on diplopia occurrence were evaluated. Diplopia was found in 48% patients who had positive test predicting the risk of post-operative diplopia. The test thus seems to be quite limited in its reliability and prior to surgery the patients should be thoroughly informed about a possibility of diplopia occurring as a surgery complication.

[Results of treatment for anisometropic amblyopia with and with squint]

Children with anisometropy greater than 1.0 D were selected from among the patients of the Squint Therapy Consulting Unit of the Ophthalmological Clinic of Medical Academy in Lódź. They were divided into two groups with or without squint. The relationships between positive results of treatment and the degree of anisometropy, initial visual acuity, patients' age and the type and duration od treatment were studied. The degree of binocular vision was evaluated as one the criterions of the recovery in both groups. Higher anisometropy was associated with higher amblyopia. The improvement was achieved in a greater percent of cases in the group with squint. The results were better in lower anisometropy and in younger children, but positive results were achieved also in older patients. There was no correlation between the age od patients and the degree of anisometropy. On account of the lack of stability in visual acuity, supporting occlusion was often indicated.

Jun and Fos heterodimerize with ATFa, a member of the ATF/CREB family and modulate its transcriptional activity

Three related clones encoding proteins (ATFa1, 2 and 3) with specific ATF/CRE DNA-binding activities have been isolated from HeLa cell cDNA libraries. All three isoforms have weak effects on the basal activity of the adenovirus E2a promoter. We present evidence suggesting that a C-terminal element of the ATFa molecules negatively interferes with the intrinsic activation function of these proteins. We also show that coexpression of ATFa with c-Jun, Jun-B or Jun-D stimulates ATFa-dependent reporter activity, while coexpression of c-Fos has no effect. Deletion analyses indicate that the metal-binding region of ATFa is dispensible for this effect, but that the domain comprising the leucine-zipper region of ATFa is required. Reciprocal co-immunoprecipitation experiments and electrophoretic band-shift assays with in vitro synthesized proteins reveal direct interactions between ATFa and Jun or Fos. The ATFa/c-Jun heterodimers, but not the ATFa/c-Fos complexes, bind efficiently to ATF, CRE or AP1 sites. The detection of ATFa-Jun complexes in crude extracts from HeLa cells transfected with ATFa and c-Jun expression vectors suggests that such ATFa/c-Jun heterodimers also form in vivo. Altogether these results indicate that the ATFa proteins may contribute to the modulation of the activity of the Jun/Fos complexes by altering their DNA-binding and transcriptional properties.

Establishment and characterization of B-like lymphoblastoid cell lines by long-term culture of primary explants from human myasthenic thymus

Using a simple method of long-term culture, it was possible to obtain B-like lymphoblastoid cell lines (LyCLs) from myasthenic thymuses. Successful cultures were carried out from 14 out of 15 hyperplastic thymuses and in 1 out of 3 myasthenic thymoma, whereas none of the 8 control thymuses, nor the 2 Myasthenia gravis-associated normally involuted thymuses, nor the Myasthenia gravis-associated lymphoma gave rise to LyCL. All the LyCLs secreted immunoglobulins (Ig), either IgG or IgM. None of these Ig reacted with acetylcholine receptor or with other antigens known to be often involved in autoimmune diseases. EBV antigens were found in all the LyCLs as well as in the corresponding donors at the time of thymectomy. HLA characterization of some LyCLs and the corresponding donors showed that class II MHC antigens were expressed normally or with mild differences. However, 86% of the LyCL tested did not express class I MHC antigens.

Transcriptional activation by the adenovirus larger E1a product is mediated by members of the cellular transcription factor ATF family which can directly associate with E1a

We recently isolated three cDNA clones encoding closely related proteins (ATFa1, ATFa2, and ATFa3) that belong to the activating transcription factor-cyclic AMP-responsive element family of cellular transcription factors. Using cotransfection experiments, we showed that these proteins mediate the transcriptional activation induced by the adenovirus E1a 13S mRNA gene product and that the zinc-binding domains present in both E1a conserved region 3 and the most N-terminal portion of the ATFa proteins play crucial roles in this activity. Reciprocal coimmunoprecipitation experiments demonstrated direct interactions between these proteins. Neither the conserved region 3 domain of E1a nor the N-terminal metal-binding element of ATFa is essential for these interactions. The simultaneous alteration of both the N-terminal and the C-terminal domains of ATFa abolished E1a binding, while either mutation alone failed to impair these interactions.

[Antiphospholipid antibodies (aPL): detection and clinical significance]

Phospholipid-binding antibodies are heterogeneous immunoglobulins of G and/or M and/or A class which can be detected in association with a variety of pathologies. However they can also occur in the absence of any clinical manifestations. Despite their paradoxical in vitro anticoagulant activity, phospholipid-binding antibodies, either primary or secondary, are frequently associated with venous and/or arterial thrombotic events. Hence, their detection has to be performed in several major clinical situations, cerebral attack, myocardial infarction, recurrent fetal loss, deep vein thrombosis ... Their course has to be controlled at least every six months. Since the incidence of phospholipid-binding antibodies in auto-immune pathologies is high, immunological disorders should also be considered. As yet there is no standardized assay of phospholipid-binding antibodies, either functional with respect to their anticoagulant activity, or immunological (ELISA). It is not established whether they possess an own pathogenic potential or appear as a secondary response following cellular alterations known to be thrombogenic. However it has been suggested that they could participate in the disruption of the hemostatic balance towards procoagulant tendency resulting in thrombosis.

Recombinational biases in the rearranged C1-inhibitor genes of hereditary angioedema patients

DNA structural changes responsible for hereditary angioedema were sought in the C1-inhibitor gene, which contains unusually dense clusters of Alu repeats in various orientations. Among patients belonging to 45 unrelated families, eight partial C1-inhibitor gene deletions and a partial duplication were found. Four deletions had one of the boundaries within the gene and the other in extragenic regions--in three cases 5' of the gene and in one case 3' of the gene. The boundaries of the partial duplication and of the remaining four deletions mapped instead within a few kilobases of exon 4. The same element--Alu 1--the first of three tandem Alu repeats preceding exon 4, contained one of the breakpoints of each of these five rearrangements. Moreover, these recombination breakpoints spread over the entire length of Alu 1, in contrast with the tight clustering observed near the 5' end of Alu sequences rearranged in other human genes. Thus, two uncommon recombinational biases are observed in the Alu rearrangements of hereditary angioedema patients; one promotes the occurrence of intragenic breakpoints in a single Alu repeat, and the other allows the breaks to be distributed over the entire Alu structure rather than within the hot spot of the left Alu monomer. A region of potential Z-DNA structure, located 1.7 kb upstream of Alu 1, may contribute to both peculiarities.

A randomized study of on-line plasma perfusion over protein A-sepharose and 5-fluorouracil chemotherapy in patients with metastatic colorectal carcinoma

To evaluate the safety of on-line plasma perfusion over protein-A sepharose and the therapeutic advantage of combining plasma perfusion (PP) over protein-A sepharose with 5-fluorouracil (5-FU) chemotherapy in patients with metastatic colorectal carcinoma (MCRC), thirty patients were randomized after surgery of primary CRC to receive a combination of 5-FU and PP over protein-A sepharose (group A), or a combination of 5-FU and PP over sepharose (group B), or 5-FU alone (group C). Bi-weekly on-line PP over 200 ml protein-A sepharose gel (group A) or 200 ml sepharose gel (group B) were performed with a Cobe 2997 blood cell separator for a maximum of 19 treatments per patient. 5-FU was given at 1000 mg/m2/d on days 1-5 of a 4-weekly cycle until progression. PP was well tolerated and no severe or life-threatening toxicity was observed. Mild clinical side-effects consisted of fever and chills (36% in group A, 23% in group B). The most common biological effects of PP over protein-A sepharose were significant drops in IgG (66% of pre-PP values), CH50 and C3 (73% of pre-PP values) and a significant generation of C3a and C5a anaphylatoxins. Tumor response rates were 40% for group A, 0% for group B and 20% for group C. The median survival times tended to be longer in group A (17 months) than in group B (10 months) and in group C (9 months). This is the first randomized trial showing some therapeutic advantage in combining PP over protein-A sepharose with conventional chemotherapy in MCRC.

A Randomized Study of On-Line Plasma Perfusion over Protein A-Sepharose and 5-Fluorouracil Chemotherapy in Patients with Metastatic Colorectal Carcinoma

To evaluate the safety of on-line plasma perfusion over protein-A sepharose and the therapeutic advantage of combining plasma perfusion (PP) over protein-A sepharose with 5-fluorouracil (5-FU) chemotherapy in patients with metastatic colorectal carcinoma (MCRC), thirty patients were randomized after surgery of primary CRC to receive a combination of 5-FU and PP over protein-A sepharose (group A), or a combination of 5-FU and PP over sepharose (group B), or 5-FU alone (group C). Bi-weekly on-line PP over 200 ml protein-A sepharose gel (group A) or 200 ml sepharose gel (group B) were performed with a Cobe 2997 blood cell separator for a maximum of 19 treatments per patient. 5-FU was given at 1000 mg/m2/d on days 1-5 of a 4-weekly cycle until progression. PP was well tolerated and no severe or life-threatening toxicity was observed. Mild clinical side-effects consisted of fever and chills (36% in group A, 23% in group B). The most common biological effects of PP over protein-A sepharose were significant drops in IgG (66% of pre-PP values), CH50 and C3 (73% of pre-PP values) and a significant generation of C3a and C5a anaphylatoxins. Tumor response rates were 40% for group A, 0% for group B and 20% for group C. The median survival times tended to be longer in group A (17 months) than in group B (10 months) and in group C (9 months). This is the first randomized trial showing some therapeutic advantage in combining PP over protein-A sepharose with conventional chemotherapy in MCRC.

A randomized study of combined 5-fluorouracil and plasma perfusion over protein A-sepharose in human advanced colorectal carcinoma

To evaluate the advantage with regard to toxicity, response rate, time to progression and survival of combination chemoimmunotherapy over single-agent chemotherapy in patients with metastatic colorectal carcinoma (CRC), 30 patients were randomized to receive a combination of 5-fluorouracil (5-FU) by continuous i.v. infusion and plasma perfusion (PP) over protein A-Sepharose (group A), or a combination of 5-FU and PP over sepharose (group B) or 5-FU alone (group C). 5-FU was given at 1,000 mg/m2/d on days 1-5 of a 4-weekly cycle until progression. Patients of groups A and B received bi-weekly on-line PPs until disease progression or for a maximum of 19 treatments. PP was well tolerated and no severe or life-threatening toxicity was observed. The response rates were 10% for the group A (1 PR), 0% for the group B and 20% for the group C (1 CR + 1 PR). The times to tumor progression for patients in groups A and C were 22 months, 12 and 11 months, respectively and the median survival times were 17 months, 10 months and 9 months. Although the time to progression and survival tended to be higher in patients treated with protein A. PP, these differences were not statistically significant. This is the first report of a randomized trial showing some therapeutic advantage in combining protein A. PP with 5-FU in CRC patients. Further randomized studies are required to demonstrate the real true value of this chemoimmunotherapeutic approach.

An estimate on the frequency of duplicated haplotypes and silent alleles of human C4 protein polymorphism. I. Investigations in healthy Caucasoid families

The frequency of duplicated and non-expressed C4 alleles was determined by segregation analysis in 31 German and five French families with altogether 274 individuals by submitting the complete data from C4 protein phenotyping, including C4 beta chains, and the other classical MHC markers to the family analysis programme (FAP). From 120 unrelated German haplotypes the following frequencies were derived for silent alleles: C4A*Q0 0.2000, C4B*Q0 0.2083, and for the total of homo- and heteroduplicated C4A resp. C4B alleles: C4"DA"* 0.1333, C4"DB"* 0.1000. The true occurrence of the duplicated C4A*2, "DB*21" haplotype, first observed in French families, was found to be 0.0250 in the German sample. While the frequency of duplicated C4 haplotypes confirms earlier estimates, the increase in the frequency of silent alleles corresponds to those assumed from investigations at the DNA level. The results demonstrate classical protein typing with inclusion of C4 beta chain types to be an indispensable and powerful tool for haplotype recognition; they support the hypothesis that deletion at one C4 locus is accompanied by duplication at the other in a majority of haplotypes.

Molecular basis of complete C4 deficiency. A study of three patients

The highly polymorphic fourth component of human complement (C4) is usually encoded by two genes, C4A and C4B, adjacent to the 21-hydroxylase (21-OH) genes and is also remarkable by the high frequency of the null alleles, C4A*Q0 and C4B*Q0. Complete C4 deficiency is exceptional because this condition appears only in homozygotes for the very rare double-null haplotype C4AQ0,BQ0. This condition in most cases gives rise to systemic lupus erythematosus and an increased susceptibility to infections. The molecular basis for complete C4 deficiency has not yet been established. Therefore we studied the DNA of three previously described C4 deficient patients belonging to unrelated families by restriction fragment length polymorphism analysis using C4 and 21-OH probes. These studies revealed a deletion of the C4B and 21-OHA genes in two patients and no deletion at all in the third patient. Therefore, complete C4 deficiency as a result of homozygosity for the C4AQ0, BQ0 haplotype is not a consequence of a deletion of the C4 genes. The molecular basis of this genetic abnormality is certainly very complex and may vary also from one case to another.

Differential utilization of the same reading frame in a Xenopus homeobox gene encodes two related proteins sharing the same DNA-binding specificity

Xenopus XlHbox 1 produces two transcripts during early development. One encodes a long open reading frame (ORF) and the other a short ORF sharing the same homeodomain, but differing by an 82 amino acid domain at the amino terminus. The long protein amino terminus is conserved with many other homeodomain proteins, and its absence from the short protein could have functional consequences. Some viral genes also utilize a single ORF to encode transcription factors of antagonistic functions. The overall organization of the homologous genes in frog and man is similar, supporting the notion that both transcripts are of functional significance. Studies on XlHbox 1 function show that the region common to the long and short proteins has a sequence-specific DNA-binding activity, and that microinjection of specific antibodies into embryos results in the loss of structures derived from cells normally expressing XlHbox 1.

[Polymorphism of C4 and factor B in type I diabetes]

The haplotypic frequencies of the fourth component of complement (C4) and factor B (Bf) have been determined in 44 Alsatian type 1 diabetics. An increased frequency of the rare allele Bf F1 (9.1% vs 1.5%) and of the silent alleles of C4 (C4 AQO: 21.6% vers 15.5% -C4 BQO: 29.6% vs 16.0%) was observed in diabetics in comparison to the general population of the same geographic area. A complete HLA haplotype determination has been obtained in 24 type 1 French diabetics. Three haplotypes were associated with the diabetic susceptibility: HLA-A30 CW5 B18 BfF1 C4A3BQO DR3 (18.75% vs 0.86%), HLA-A1 CW7 B8 BfS C4AQOB1 DR3 (15.58% vs 4.17%), HLA-A2 CW3 BW62 BfS C4A3B3 DR4 (6.25% vs 0.45%). The authors suggest that the silent alleles of C4 could modulate the expression of the diabetic susceptibility genes by lowering of the serum C4 hemolytic activity.

Antigenic determinants expressed by human C4 allotypes; a study of 325 families provides evidence for the structural antigenic model

The antigenic determinants of human C4 have been defined by human IgG antisera, Rodgers (Rg) and Chido (Ch), in hemagglutination-inhibition assays (HAI). Eight (2 Rg and 6 Ch) are of high frequency, greater than 90%, and 1, WH, is of low frequency, 15%. The phenotypic combinations are complex; generally, C4A expresses Rg, and C4B has Ch, but reverse antigenicities have been established both by HAI and by sequence data of selected C4 allotypes. A study of 325 families provides data on the antigenic expression of each C4 allotype and demonstrates strong associations. A structural model for the antigenic determinants of C4 proteins has been proposed and is completely supported by the family material. Of the 16 possible antigenic combinations for C4 proteins, only 3 are undetected. A new Ch combination has been recorded in two French families. The reported sequence variation within the C4d region can account for the antigenic determinants but leaves the location of electrophoretic variation in C4 still unclear.

Complement C4 phenotypes in dementia of the Alzheimer type

Complement C4 phenotype distribution was studied in 64 patients with dementia of the Alzheimer type. In contrast to reported findings we failed to find a significant association between C4B2 gene frequency and Alzheimer's dementia.

The study of a French family with two duplicated C4A haplotypes

The finding of two duplicated C4A haplotypes in a normal French family led to a detailed study of their C4 polymorphism. The father had an extremely rare A*6A*11, B*QO haplotype inherited by all of his children and the mother had the more common A*3A*2, B*QO haplotype. Two HLA identical daughters only have four C4A alleles. The father's A11 allotype expresses Ch:1 (Chido) rather than Rg:1 (Rodgers) and represents a new Ch phenotype Ch:1,-2,-3,-4,-5,-6. In order to clarify the genetic background in this unusual family, DNA studies of restriction fragment length polymorphisms (RFLPs) were undertaken. The father's rare haplotype, which expresses two C4A allotypes, results from a long and a short C4 gene normally associated with the A*6, B*1 that also exhibits the Bg/II RFLP. As it travels in an extended MHC haplotype HLA A2, B57(17), C2*C, BF*S, DR7 that is most frequently associated with A*6, B*1, we postulate that the short C4B has been converted in the alpha chain region to a C4A gene which produces a C4A protein. This report of a short C4A gene is the first example in the complex polymorphism of C4.