Surgical management of dysthyroid diplopia with preservation of the anterior ciliary vascularization: review of ten cases.

PURPOSE: During the surgical correction of dysthyroid diplopia, the risk of ischemia by transection of the anterior ciliary arteries is well-known. In order to avoid this, we modified the classical surgical technique: (1) through the preservation of the vascular pedicles during muscle recession and (2) if necessary, through a plication (instead of a resection) of the ipsilateral antagonist muscle. The objective to be achieved is thus the resolution of the diplopia without ischemic complications. SUBJECTS AND METHODS: We report a prospective series of 10 patients with dysthyroid ophthalmopathy, causing strabismic diplopia, all operated on by the same surgeon (BR) after at least 12 months of euthyroidism. Data collection included: history of previous decompressive surgery, surgical procedure, and oculomotor status before and after surgery. RESULTS: Ten patients (8 females), aged 51 to 74 years (mean age, 58.00 ± 7.62 years), were collected between 2008 and 2012. All patients had one or more vascular risk factors (diabetes, smoking, obesity, high blood pressure). With a follow-up from 16 to 67 months (mean ± SD 27.7 months ± 14.87), surgical outcomes were excellent: diplopia was cured in all cases, with recovery of stereoscopic vision. We had no operative or postoperative complications. CONCLUSIONS: The technique of preservation of the anterior ciliary vascularization, which is particularly justified for these fragile patients, is compatible with moderate muscle recessions. For larger deviations, in which a larger recession might increase the proptosis, it is possible to add a plication of the ipsilateral antagonist. This surgical technique made possible the suppression of the diplopia in all cases.

Meeting the demand for innate and adaptive immunities during evolution.

An ideal immune system should provide each individual with rapid and efficient responses, a diverse repertoire of recognition and effector molecules and a certain flexibility to match the changing internal and external environment. It should be economic in cells and genes. Specific memory would be useful. It should not be autoreactive. These requirements, a mixture of innate and adaptive immunity features, are modulated in function of the dominant mode of selection for each species of metazoa during evolution (K or r). From sponges to man, a great diversity of receptors and effector mechanisms, some of them shared with plants, are articulated around conserved signalling cascades. Multiple attempts at combining innate and adaptive immunity somatic features can be observed as new somatic mechanisms provide individualized repertoires of receptors throughout metazoa, in agnathans, prochordates, echinoderms and mollusks. The adaptive immunity of vertebrates with lymphocytes and their specific receptors of the immunoglobulin superfamily, the major histocompatibility complex, developed from innate immunity evolutionary lines that can be traced back in earlier deuterostomes.

Heterogeneity of endothelial junctions is reflected by differential expression and specific subcellular localization of the three JAM family members.

Endothelial cells are linked to each other through intercellular junctional complexes that regulate the barrier and fence function of the vascular wall. The nature of these intercellular contacts varies with the need for permeability: For example, in brain the impervious blood-brain barrier is maintained by "tight" contacts between endothelial cells. By contrast, in high endothelial venules (HEVs), where lymphocytes continuously exit the bloodstream, the contacts are generally leaky. The precise molecular components that define the type of junction remain to be characterized. An immunoglobulin superfamily molecule named JAM-2, specifically expressed in lymphatic endothelial cells and HEVs, was recently identified. JAM-3 was cloned and characterized in the current study, and JAM-1, -2, and -3 were shown to form a novel protein family belonging to the larger cortical thymocyte Xenopus (CTX) molecular family. Using antibodies specific for each of the 3 family members, their specific participation in different types of cell-cell contact in vivo and their specific and differential localization in lateral contacts or tight junctions were demonstrated. Furthermore, it was shown that JAM-1 and JAM-2 differentially regulate paracellular permeability, suggesting that the presence of JAM-1, -2, or -3 in vascular junctions may play a role in regulating vascular function in vivo.

Major histocompatibility complex and immunoglobulin loci visualized by in situ hybridization on Xenopus chromosomes.

A technique for fluorescent in situ hybridization (FISH) on chromosomes of the amphibian Xenopus laevis is described. Positive results were obtained with cDNA probes of about 1kb when at least three adjacent copies of the gene are present. The immunoglobulin heavy chain locus is in the centre of the long arm of chromosome 1. Previously, family studies showed that bona fide MHC class Ib genes segregated independently. Now we show that MHC class II alpha and beta genes and class Ib genes are on the same acrocentric chromosome, with MHC in the middle of the long arm, the class Ib complex (XNC) at the tip or the same arm. Each locus or complex is found on only one pair of chromosomes confirming the diploidization of these genes in the pseudotetraploid X. laevis.

Biochemical analysis of the Xenopus laevis TCR/CD3 complex supports the "stepwise evolution" model.

The TCR/CD3 complex of a cold-blooded vertebrate, the amphibian Xenopus laevis, was biochemically characterized with a cross-reactive polyclonal antiserum recognizing a conserved epitope in the cytoplasmic domain of CD3E. The specificity and utility of this reagent was validated by Western blot analysis and immunoprecipitation of the well-characterized chicken TCR/CD3 complex. Cross-reactivity with the X. laevis CD3E protein was demonstrated by specific staining of sorted CD8+ cells. Immunohistology on both tadpoles and adult tissues suggests this antiserum will be instrumental in the localization of Xenopus T cells and most likely NK cells. Double staining of tissue sections with an anti-CD8 monoclonal antibody confirmed that this staining is specific. The antiserum was also used for the biochemical analyses of X. laevis TCR/CD3 complex. The 75-kDa alphabeta TCR heterodimer could be separated into a 40-kDa acidic TCR alpha chain and a 35-kDa basic TCR beta chain. Two CD3 proteins, both comigrating at approximately 19 kDa, were associated with the TCR heterodimer. Removal of N-linked carbohydrates yielded CD3 proteins of 19 kDa and 16.5 kDa, most likely representing the CD3epsilon and CD3gamma/delta homologues, respectively. An additional band of 110 kDa represents a multimeric complex of the TCR heterodimer covalently linked to a CD3 dimer. These properties of the Xenopus TCR/CD3 complex substantiate a stepwise evolutionary model for the CD3 protein family.

B-cell development in the amphibian Xenopus.

The amphibian Xenopus and mammals have similar organization and usage of their immunoglobulin gene loci with combinatorial joining of V, D and J elements. The differences in B-cell development between mammals and this amphibian are due to major differences in developmental kinetics, cell number and lymphoid organ architecture. Unlike mammals, the immune system of Xenopus develops early under pressure to develop quickly and to produce a heterogeneous repertoire before lymphocyte numbers reach 5,000, thereby imposing a limitation on clonal amplification. In addition, it is submitted to metamorphosis. Thus, during the early antigen-independent period, several features of B-cell development related to immune diversification are under strict genetically preprogramed control: 1) D reading frames contribute complementary determining region 3 with features that occur in mammals by somatic selection, 2) the temporal stepwise utilization of V(H) genes in Xenopus occur in families probably because of structural DNA features rather than their position in the locus. Larval and adult immune responses differ in heterogeneity. Larval rearrangements lack N diversity. During the course of immune responses, somatic mutants are generated at the same rate as in other vertebrates but are not optimally selected, probably due to the simpler organization of the lymphoid organs, with neither lymph nodes nor germinal centers resulting in poor affinity maturation. Switch from IgM to other isotypes is mediated by loop-excision deletion of the IgM constant region gene via switch regions which, unlike their mammalian counterpart, are A-T rich and reveal conserved microsites for the breakpoints.

Trans-species polymorphism of the major histocompatibility complex-encoded proteasome subunit LMP7 in an amphibian genus, Xenopus.

LMP7 (PSMB8) is a major histocompatibility complex (MHC)-encoded catalytic subunit of 20S immunoproteasome, which is responsible for the production of antigenic peptide to be presented by the MHC class I molecules. Two highly diverged allelic lineages of LMP7, termed LMP7A and LMP7B, have been identified previously in an amphibian, Xenopus laevis. Fourteen Xenopus species were analyzed by genomic Southern hybridization using LMP7A- and LMP7B-specific probes. Ten had both LMP7A and LMP7B, and the other 4 had only LMP7A. Identification of LMP7A and LMP7B was confirmed by reverse transcription-polymerase chain reaction/sequencing analysis of LMP7 mRNA including eight diagnostic amino acid residues that discriminate the two allelic lineages. These data suggest that these two allelic lineages were established more than 80 million years ago, and were transmitted from species to species. Trans-species evolution has so far been reported for MHC class I and II molecules in mammals and teleost fish, and is believed to be a basis for the extraordinary polymorphism of these molecules. A similar mode of evolution of the LMP7 alleles in Xenopus provides a possible explanation for the linkage of the LMP7 gene with the MHC in all vertebrates analyzed to date.

Axolotl MHC architecture and polymorphism.

The MHC of the urodele amphibian Ambystoma mexicanum consists of multiple polymorphic class I loci linked, so far as yet known, to a single class II B locus. This architecture is very different from that of the anuran amphibian Xenopus. The number of class I loci in the axolotl can vary from 6 to 21 according to the haplotypes as shown by cDNA analysis and Southern blot studies in families. These loci can be classified into seven sequence groups with features ranging from the class Ia to the class Ib type. All individuals express genes from at least three of the seven groups, and all individuals possess the class Ia-like type.

Secondary thyroidectomy in patients with prior thyroid surgery for benign disease: a study of 203 cases.

BACKGROUND: The goal of this study was to evaluate the complication rate of secondary thyroidectomy in patients with prior thyroid surgery for benign disease. METHODS: Over an 8-year period, 203 thyroid reoperations were performed on 202 patients. All information relating to operative procedures, pathology, and complications was recorded prospectively. RESULTS: There were 24 men and 178 women with a mean age of 52 years. Prior surgery was unilateral in 136 cases (67%) and bilateral in 67 cases (33%), and 14 patients (6.9%) had more than 1 previous thyroid operation. For euthyroid or pretoxic recurrent nodular goiter, 190 reoperations were performed and 13 reoperations were performed for recurrent thyrotoxicosis. Twenty-three cancers were found in a specimen (11.4%). Completion thyroidectomy was done in 143 patients. Postoperative complications occurred in 21 patients (10.4%): recurrent laryngeal nerve palsy (7 patients), hypocalcemia (8 patients), hematoma requiring surgical evacuation (5 patients), and wound infection (1 patient). Complications remained permanent in 4 patients (2%). CONCLUSIONS: The permanent complication rate is higher in thyroid reoperations than in primary thyroid operations. However, we believe that this 2% rate is low enough to allow reoperation whenever it is necessary, provided precise operative rules are respected.

Two ancient allelic lineages at the single classical class I locus in the Xenopus MHC.

Unlike all other vertebrates examined to date, there is only one detectable class I locus in the Xenopus MHC. On the bases of a nearly ubiquitous and high tissue expression, extensive polymorphism, and MHC linkage, this gene is of the classical or class Ia type. Sequencing analysis of class Ia cDNAs encoded by eight defined MHC haplotypes reveals two very old allelic lineages that perhaps emerged when humans and mice diverged from a common ancestor up to 100 million years ago. The unprecedented age of these lineages suggests that different class Ia genes from ancestors of the laboratory model Xenopus laevis are now expressed as alleles in this species. The lineages are best defined by their cytoplasmic and alpha2 peptide-binding domains, and there are highly diverse alleles (defined by the alpha1 peptide-binding domain) in each lineage. Surprisingly, the alpha3 domains are homogenized in both lineages, suggesting that interallelic gene conversion/recombination maintains the high sequence similarity.

Expression, linkage, and polymorphism of MHC-related genes in rainbow trout, Oncorhynchus mykiss.

The architecture of the MHC in teleost fish, which display a lack of linkage between class I and II genes, differs from all other vertebrates. Because rainbow trout have been examined for a variety of immunologically relevant genes, they present a good teleost model for examining both the expression and organization of MHC-related genes. Full-length cDNA and partial gDNA clones for proteasome delta, low molecular mass polypeptide (LMP) 2, TAP1, TAP2A, TAP2B, class Ia, and class IIB were isolated for this study. Aside from the expected polymorphisms associated with class I genes, LMP2 and TAP2 are polygenic. More specifically, we found a unique lineage of LMP2 (LMP2/delta) that shares identity to both LMP2 and delta but is expressed like the standard LMP2. Additionally, two very different TAP2 loci were found, one of which encodes polymorphic alleles. In general, the class I pathway genes are expressed in most tissues, with highest levels in lymphoid tissue. We then analyzed the basic genomic organization of the trout MHC in an isogenic backcross. The main class Ia region does not cosegregate with the class IIB locus, but LMP2, LMP2/delta, TAP1A, and TAP2B are linked to the class Ia locus. Interestingly, TAP2A (second TAP2 locus) is a unique lineage in sequence composition that appears not to be linked to this cluster or to class IIB. These results support and extend the recent findings of nonlinkage between class I and II in a different teleost order (cyprinids), suggesting that this unique arrangement is common to all teleosts.

Duplication and MHC linkage of the CTX family of genes in Xenopus and in mammals.

The effects of whole genome duplications that characterize the evolution of vertebrates have been studied on the gene of the Xenopus thymocyte molecule CTX and its mammalian relatives. CTX, with an extracellular part consisting of one V and one C2 external domain, defines a new subset of the immunoglobulin superfamily and is conserved from amphibians to mammals. The number of CTX loci, their polymorphism, and their genetic linkages have been studied in several Xenopus species and in humans. In the genetically simplest species, X. tropicalis (2n = 20), the unique CTX locus is linked to the MHC. In the polyploid species, all CTX genes, unlike many other immune system genes, have remained in the genome; i.e. there are two CTX loci in the tetraploid species X. laevis (2n = 6) and six CTX loci in the dodecaploid species X. ruwenzoriensis (2n = 108). In X. laevis, one CTX gene is linked to the MHC and the other not, presumably because one set of MHC class I and II has been deleted from the corresponding linkage group. The various mammalian homologues are less related to each other than are the Xenopus CTX genes among each other, and they do not cross-hybridize with each other because they stem from the ancient polyploidization. Some human CTX homologies are on chromosomes 11 and 21, but others are on chromosomes 1, 6 and 19, which contain MHC paralogous regions; this suggests that a very ancient linkage group has been preserved.

CTX, a Xenopus thymocyte receptor, defines a molecular family conserved throughout vertebrates.

CTX, a cortical thymocyte marker in Xenopus, is an immunoglobulin superfamily (Igsf) member comprising one variable and one constant C2-type Igsf domain, a transmembrane segment and a cytoplasmic tail. Although resembling that of the TCR and immunoglobulins, the variable domain is not encoded by somatic rearrangement of the gene but by splicing of two half-domain exons. The C2 domain, also encoded by two exons, has an extra pair of cysteines. The transmembrane segment is free of charged residues, and the cytoplasmic tail (70 amino acids) contains one tyrosine and many glutamic acid residues. ChT1, a chicken homologue of CTX, has the same structural and genetic features, and both molecules are expressed on the thymocyte surface. We cloned new mouse (CTM) and human (CTH) cDNA and genes which are highly homologous to CTX/ChT1 but not lymphocyte specific. Similarity with recently described human cell surface molecules, A33 antigen and CAR (coxsackie and adenovirus 5 receptor), and a number of expressed sequence tags leads us to propose that CTX defines a novel subset of the Igsf, conserved throughout vertebrates and extending beyond the immune system. Strong homologies within vertebrate sequences suggest that the V and C2 CTX domains are scions of a very ancient lineage.

Development of the early B cell population in Xenopus.

Like mammals, the amphibian Xenopus uses combinatorial joining of the immunoglobulin V, D and J elements and multiple rearrangements to generate its B cell repertoire. Xenopus larvae hatch 2 days after fertilization and individuals are under pressure to develop an immune repertoire when the number of available cells is small (approximately 5 and 200 IgM-positive cells on days 5 and 11 after fertilization, respectively). In the liver, in a first phase of differentiation spanning days 5-12 after fertilization before immunological competence, the heavy (H) chain locus starts rearranging followed by the light (L) chain locus 3 days later. By immunohistology the first B cells expressing H and L chain are detectable on day 10. Despite the small number of cells available and the lack of external antigen selection at these early stages, the repertoire is heterogeneous. The VH families are used stepwise, although their genes are interspersed in the genome. The earliest family used (VH1) is homologous to the VH3 family of human and to the VH7183 of the mouse which are also overrepresented in early mammalian development. In the second phase, from day 12-13 onwards, the spleen differentiates and the animal becomes immunologically competent. The V, D and J usage is similar to that of adults although VDJ junctions lack N nucleotides until metamorphosis. A preferential reading frame for D and one specific DJ junction are overrepresented during this second phase. The visible bias toward homology-based junction results in fact from selection after rearrangement.