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E Lamoyi

Publications and source records attributed to E Lamoyi.

At least 19 recordsLinked to original sources
PubMed2006

In vitro cell fusion between CD4(+) and HIV-1 Env(+) T cells generates a diversity of syncytia varying in total number, size and cellular content.

Syncytia formation in HIV infections is driven by the virus fusion-active molecules (Env) interacting with membrane components of hosts cells. HIV-syncytia are usually interpreted as pathogenic entities and although they may potentially vary in size, numbers and types of constituent cells, little is known about the extent and significance of their diversity. Here, we describe numerically the cell population dynamics and the diversity of syncytia produced in the in vitro cell-fusion between two Jurkat T cell lines, one CD4(+) and the other Env(+). Cell-fusion partners were differentially stained with the lipophilic DiI and DiO, or with the cytoplasmic CMFDA and CMTMR tracers and syncytia showing double fluorescence were counted in a flow cytometer. The total number of syncytia formed, their size, cellular complexity and ratio of CD4(+)/Env(+) cells recruited, varied significantly in relation with time of reaction and initial proportions of fusion partners. The considerable structural diversity of syncytia formed, in so limited an in vitro cell fusion reaction, suggests that a greater heterogeneity may be formed in the natural course of disease. Identification of the main determinants of syncytia diversity allows for a detailed study of the relation between the syncytia structure and function.

CD4 Antigens↗
PubMed2005

Human immunodeficiency virus 1 (HIV-1) envelope-dependent cell-cell fusion modulation by HIV-positive sera is related to disease progression.

Fusion of CD4+ cells by HIV-1 envelope proteins (Env) is a mechanism of virus spread and cell damage. Production of antibodies able to influence cell-cell fusion in vivo may affect the course of the infection. The effect of sera from 49 HIV-1-positive patients was tested on an in vitro fusion assay using Env-expressing and normal Jurkat T cells labelled with DiI and DiO dyes, and flow cytometry for quantification of cell-cell fusion. Sera varied in their activity on fusion: 69.4 % inhibited, 24.5 % had no effect and 6.1 % enhanced cell fusion. Fusion activity correlated positively with the CD4+ T-cell count and inversely with the viral load. Removal of IgG or IgM from sera reduced or eliminated inhibition and enhancing activities, respectively. Antibodies with inhibitory activity predominate in early and intermediate stages of infection, whereas loss of inhibition or enhancement of fusion correlates with progression to AIDS.

Cell Fusion↗
PubMed2001

Developmental regulation of connexin 43 expression in fetal mouse testicular cells.

Multiple connexins have been identified in testicular cells. Several lines of evidences indicate that, among them, connexin 43 (Cx43) may be unique for control of gonad development and spermatogenesis. To date, however, it is not known whether Cx43 is expressed in the fetal testis and what possible types of cellular interactions mediated by this connexin are critical to male fertility. In the present work, expression of Cx43 was investigated at various developmental ages in cryosections from mouse testis by using specific antibodies against Cx43. In serial or double-labeled sections, Cx43 localization was compared with immunocytochemical distribution of steroidogenic enzyme, 3beta-hydroxysteroid dehydrogenase (3betaHSD), Mullerian inhibitory hormone (MIH), and germinal nuclear cell antigen (GCNA1), which are specific markers, respectively, of interstitial Leydig, Sertoli, and germinal cells. Sections were analyzed by fluorescence microscopy. We found that Cx43 immunofluorescence (IF) was uniformly distributed in the undifferentiated gonad at 11.5 days post coitus (dpc) and in cells of the mesonephric tubules. In the undifferentiated gonad, Cx43 was localized between primordial germ cells and somatic cells. At 12.5 dpc, when the gonad has undergone sexual differentiation, in the interstitium Cx43 was localized in Leydig cells and in the seminiferous cord it was localized between adjacent Sertoli cells. In Leydig and Sertoli cells, Cx43 labeling increased at 14.5, 16.5, and 18.5 dpc. From day 12.5 up to 18.5 dpc, Cx43 was also localized in cell borders between germinal and Sertoli cells. In conclusion, this study demonstrates that from the earliest stages of gonadal development, Cx43 is expressed in the principal cell types that participate in the control of male fertility. It also shows that Cx43 expression in Leydig and Sertoli cells increase during fetal life. Finally, it provides evidence that, throughout embryonic life, Cx43 forms gap junctions between Sertoli and germinal cells.

Animals↗
PubMed2001

Expression of connexin43 in mouse Leydig, Sertoli, and germinal cells at different stages of postnatal development.

Connexin 43 (Cx43) is the most abundant and ubiquitously distributed gap junction protein in testicular cells. Lack of Cx43 expression results in male infertility. We investigated whether Cx43 is expressed and regulated in Leydig, Sertoli and germinal cells at different stages of postnatal development. Cx43 was detected using three different antibodies shown by immunoblotting to be highly specific. At different postnatal ages Cx43 localization was compared in serial or double labeled testicular cryosections with immunocytochemical distribution of steroidogenic enzyme, 3 betahydroxysteroid-dehydrogenase (3betaHSD), Mullerian inhibitory hormone (MIH), and germinal nuclear cell antigen (GNCA1), which are specific markers of interstitial Leydig, Sertoli and germinal cells, respectively. In the interstitium, round cell clumps (RCC) with lipid droplets positive for 3betaHSD and Cx43 were frequently found at intertubular areas at birth and Cx43 was mainly localized at cell membrane appositions. From day 3, the number and size of 3betaHSD-positive RCC started to decrease, and reached a minimum at 7-14 dpp; Cx43 expressed by them is progressively downregulated. From day 21 an increase in the size and number of RCC positive for Cx43 and 3betaHSD was found that continued at 24, 26 and 28 days and reached a maximum at 35 and 60 dpp. Biphasic expression of interstitial Cx43 and 3betaHSD was also found to be positively and temporally correlated with fluctuations in intratesticular testosterone content at all ages studied. In the seminiferous cord (SC), Cx43 was expressed at birth between adjacent Sertoli cells (MIH positive) localized at the periphery, as well as in their cytoplasm projections that surround centrally localized gonocytes. From days 3 to 7, Cx43 labeling increased in Sertoli cells mainly at their apical border. At day 14, Cx43 distribution in Sertoli cells changed from apical to basal in parallel to migration of germinal (GNCA1-positive) cells from the periphery to the center of the SC. At all these ages, Cx43 was also localized at cell borders between Sertoli and germinal cells. In conclusion, this study demonstrates that Cx43 in Leydig cells is regulated during postnatal development in an age and functional dependent manner. In the tubule, it is demonstrated that Cx43 is modulated in Sertoli cells during the neonatal and prepubertal period. We also provide evidence for the first time that Cx43-gap junctions communicate between Sertoli and germinal cells before and during the first wave of spermatogenesis.

3-Hydroxysteroid Dehydrogenases↗
PubMed2001

Effect of oral zinc supplementation upon Taenia crassiceps murine cysticercosis.

The effect of zinc supplementation on Taenia crassiceps murine cysticercosis was studied in susceptible BALB/cAnN mice. Female offspring of mice supplemented with high zinc throughout gestation and lactation were intraperitoneally infected with T. crassiceps cysticerci. Offspring from nonsupplemented mothers were used as controls. Significantly fewer parasites were recovered from zinc-supplemented mice (Zsm) 30 days after infection. Increased resistance was not related to the IgG antibody response. At early stages of infection, T cells from Zsm proliferated to T. crassiceps antigens, whereas cells from control mice did not respond. Infection caused in both groups a decrease in CD3+ cell percentages, which was more pronounced in the controls, and paralleled by a decrease in CD8+ cells; CD3+ and CD8+ percentages returned to normal levels at later stages of infection. In contrast, the CD4+ subpopulation only decreased in control mice. Intracellular cytokine determinations indicate that zinc supplementation favored a stronger and persistent type-1 T cell response in cysticerci-infected mice, which probably participates in the observed increased resistance.

Administration, Oral↗
PubMed1998

Increased resistance to Taenia crassiceps murine cysticercosis in Qa-2 transgenic mice.

We previously reported important differences in resistance to Taenia crassiceps murine cysticercosis between BALB/c substrains. It was suggested that resistance might correlate with expression of the nonclassic class I major histocompatibility complex (MHC) Qa-2 antigen; BALB/cAnN is Qa-2 negative and highly susceptible to T. crassiceps, whereas BALB/cJ expresses Qa-2 and is highly resistant. In this study, we investigated the role of Qa-2 in mediating resistance to cysticercosis by linkage analysis and infection of Qa-2 transgenic mice. In BALB/cAnN x (C57BL/6J x BALB/cAnN)F1 and BALB/cAnN x (BALB/cJ x BALB/cAnN)F1 backcrosses, the expression of Qa-2 antigen correlated with resistance to cysticercosis. Significantly fewer parasites were recovered from infected Qa-2 transgenic male and female mice than from nontransgenic mice of similar genetic background. These results clearly demonstrate that the Qa-2 MHC antigen is involved in resistance to T. crassiceps cysticercosis.

Animals↗
PubMed1996

Genetic control of susceptibility to Taenia crassiceps cysticercosis.

We previously reported that genes within the major histocompatibility complex influence the intensity of Taenia crassiceps murine cysticercosis. This genetic control, readily apparent in mice of BALB background, was further studied in H-2 congenic and recombinant B10 mice as well as in BALB/c substrains differing in expression of Qa-2 antigens. Similarly low parasite numbers were found in all B10-derived strains infected, regardless of H-2 haplotype, indicating that the effect of H-2 genes in controlling susceptibility is overridden in mice of B10 background. BALB/c substrains differed significantly in susceptibility. BALB/cAnN was highly susceptible, whereas BALB/cJ, in contrast, was highly resistant and BALB/cByJ showed intermediate susceptibility. Susceptibility or resistance in BALB/c substrains may be associated to differences known to distinguish them, such as serum testosterone levels and Qa-2 protein expression. In bidirectional F1 hybrids of C57BL/6J and BALB/cAnN resistance to cysticercosis was inherited as a dominant autosomal trait. In F1 hybrids of BALB/cJ with BALB/cAnN, BALB/cByJ and BALB.K resistance was also inherited as a dominant trait. However, in (BALB/cAnN x BALB/cByJ)F1 and (BALB/cAnN x BALB.K)F1 hybrids, dominant susceptibility to cysticercosis was observed.

Animals↗
PubMed1995

Carbohydrate epitopes of Entamoeba histolytica cell surface glycoproteins are major targets of the human humoral response.

The antigens of Entamoeba histolytica recognized by antibodies in 11 individual sera from patients treated for amebic liver abscess were determined both by immunoprecipitation of metabolically-radiolabeled whole trophozoite proteins and by immunoblotting.Collectively, twenty-s even antigens ranging from 167 to 21 kDa were detected in immunoblots of whole trophozoite extracts; eight of these were recognized by all tested patient sera. Immunoprecipitation studies also revealed a complex amebic antigenic profile. Of a total of twenty immunoprecipitated polypeptides (from 200 to 24 kDa), seventeen were uniquely recognized by the patient sera. Eight of these seventeen antigens were immunoprecipitated by most immune sera. The cellular localization of trophozoite antigens was determined by analyzing plasma membrane and soluble cytosol fractions. Plasma membranes contained virtually as many antigenic moieties as the total trophozoite extract; in contrast, the soluble fraction was antigenically less complex. Mild periodate oxidation of plasma membrane antigens indicated that surface glycoproteins are highly immunogenic for the human host and that antibodies to their carbohydrate epitopes are a major component of the total response of most patients.

Animals↗
PubMed1995

Depressed T-cell proliferation associated with susceptibility to experimental Taenia crassiceps infection.

Peritoneal infection with Taenia crassiceps cysticerci of naturally resistant (C57BL/10J and C57BL/6J) and susceptible (BALB/cAnN) mice induces a cellular immune depression. T-cell proliferation in response to concanavalin A (ConA) or anti-CD3 was significantly depressed in infected mice of all strains tested. However, in resistant mice, the diminished response to ConA was transient and animals recovered normal responsiveness at day 40, whereas susceptible mice remained suppressed throughout the 40 days of the experiment. In contrast, the proliferative response to anti-CD3 was lower in infected mice than in noninfected controls regardless of differences in natural susceptibility of the strains. Intraperitoneal injection of mice with a parasite extract also induced a depression of the response to ConA, although not as strong as that produced by the parasite itself. This depression is not due to direct effects by parasite antigens over host lymphocytes, as proliferation is not affected by the presence of cysticercal antigens added in vitro. Diminished interleukin-2 production during the parasitosis accounts at least in part for the diminished responses to ConA. A primary infection favors parasite establishment after a second challenge, pointing to the relevance of the immunodepression in generating a host environment favorable to the parasite.

Animals↗
PubMed1990

Antigens in electron-dense granules from Entamoeba histolytica as possible markers for pathogenicity.

In vitro interaction of Entamoeba histolytica with collagen induces intracellular formation and release of electron-dense granules (EDG) and stimulation of collagenolytic activity. Purified EDG contain 1.66 U of collagenase per mg of protein. Thus, EDG may participate in tissue destruction during invasive amebiasis. Monoclonal antibodies (MAbs) L1.1 and L7.1 reacted specifically with EDG in enzyme-linked immunosorbent assay (ELISA) and immunofluorescence and immunoelectron microscopy. MAb L7.1 immunoprecipitated three polypeptides with molecular weights of 95,000, 68,000, and 28,000 from lysates of biosynthetically labeled E. histolytica. Both MAbs recognized the pathogenic E. histolytica axenic strains HM1:IMSS, HM38:IMSS, and HK-9 but failed to react in ELISA with Entamoeba moshkovskii, Entamoeba invadens, and E. histolytica-like Laredo. In addition, MAb L7.1 reacted with one E. histolytica isolate from a symptomatic patient but did not react with four of five isolates from asymptomatic patients. EDG antigens were detected by a MAb L7.1-based ELISA in E. histolytica-containing fecal samples from symptomatic, but not asymptomatic, individuals. These results suggest that the EDG antigen detected with MAb L7.1 may be differentially expressed in pathogenic and nonpathogenic E. histolytica.

Animals↗
PubMed1989

Allotypes of the constant region of the rabbit T cell receptor beta-2 chain.

Our laboratory previously reported that there was restriction fragment length polymorphism of TCR C beta genes in rabbits. EcoRI digests of DNA from different rabbits gave fragments of 9 and 6 kb (C beta a) or 14 and 6 kb (C beta b) that hybridized to a C beta cDNA probe. We also reported that the 9- and 14-kb types segregated as Mendelian traits and that there were allotypic differences in the first exon of the C beta 1 genes of C beta a and C beta b animals. Here we report the DNA sequence of the C beta 2 gene present in the 6-kb EcoRI fragment from a C beta b animal and compare the exon sequences with that of a cDNA from a C beta a animal. We find replacement changes in the first and third exons that probably represent allotypic forms of the rabbit C beta 2 gene. The genomic DNA 5' of exon 1 of both beta 1 and beta 2 contain alternating purine/pyrimidine repeat sequences. The genomic C beta 2 has an open reading frame of 69 amino acids in frame with exon 1 similar to a longer one previously found 5' of exon 1 of C beta 1. Further 5' of this region, rabbit C beta 1 and C beta 2 DNA sequences are only about 66% similar. Both the C beta 1 and C beta 2 sequences have two chi sequences; one in exon 1 with a perfect match and one in the intron downstream of exon 1 with one mismatch. Alternating purine/pyrimidine repeats and chi sequences found in rabbit C beta 1 and C beta 2 genes may have contributed to process(es) of gene duplication and/or conversion.

Amino Acid Sequence↗
PubMed1989

Genomic sequence and organization of rabbit Tcrb constant region genes.

We previously reported that some rabbits have three different copies of T-cell receptor b (Tcrb) constant region genes unlike man, mice, and rats who generally have two copies. Two of these C beta genes were found on an approximately 14 kilobase (kb) and one on an approximately 6 kb Eco RI fragment. The gene on the 6 kb fragment is of beta 2 type. A previously described portion of the 14 kb fragment appeared to have sequences characteristic of C beta 1. We have now shown that the 6 kb fragment is adjacent to and 3' of the 14 kb fragment. Furthermore, the second linked sequence of C beta gene present on the 14 kb fragment resembles to a large extent the C beta 2 gene present on the 6 kb fragment. Moreover, this second C beta gene has a 5' cluster of J beta sequences resembling J beta 2 of other species. However, exon 4 and the 3' untranslated region (3'UT) are of the beta 1 type. Mapping studies using Southern analyses of both genomic DNA and the 14 kb clone have identified another cluster of J beta 2 sequences 5' of the third tandem C beta 2 gene present on the 6 kb Eco RI fragment. Thus, the second gene on the 14 kb fragment appears to be a chimeric genomic Tcrb gene that may have arisen by an unequal crossing-over event analogous to that which may have deleted C beta 1, D beta 2, and J beta 2 in NZW mice.

Animals↗
PubMed1988

Linked genetic markers of the rabbit kappa light chain are not linked to the Tcr beta chain genes.

In order to investigate linkage, we used serum allotypes of the two rabbit C kappa isotypes and restriction fragment length polymorphisms (RFLPs) of the genes for V kappa, C kappa, and T-cell receptor C beta. The inheritance of these genetic markers was studied through backcross and F2 matings. Southern analysis and hybridization of genomic DNA with a C kappa probe detected a 5 kb Pst I fragment linked to expression of the K2bas1 allotype and the presence of the kappa 1bbas gene and a 6.6 kb Pst I fragment linked to the expression of the K1b9 allotype, the presence of the kappa 2bas2 gene and lack of expression of the K2bas1 allotype. A V kappa probe detected a 1.3 kb Eco RI fragment linked to the presence of the kappa 1bbas gene and expression of the K2bas1 allotype. In contrast, the 9 or 14 kb Eco RI RFLP (C beta a or C beta b) detected with a Tcr beta chain probe segregated independently from C kappa allotypes and RFLPs. It has previously been found that C kappa and C beta are also unlinked in man, whereas in the mouse they are linked at a distance of approximately 8 centimorgans.

Animals↗
PubMed1987

Genomic DNA encoding rabbit T cell receptor beta-chains: isotypes and allotypes of C beta.

We have discovered sequence differences in DNA encoding the first exon of rabbit T cell receptor beta-chains from unrelated rabbits that probably reflect allelic C beta 1 allotypes. Rabbit I was from a colony bred to maintain the K1-expression mutation Basilea, and rabbit II was from a colony bred to maintain the K1b9 allotype. Genomic DNA from rabbits I and II also exhibit restriction fragment length polymorphism of C beta on Southern blots. In addition, several different restriction enzyme digests of DNA from rabbit I give three bands, whereas DNA from rabbit II gives two when probed with C beta. An approximately 14-kb cloned genomic DNA fragment from rabbit I has two copies of C beta exon 1 and a 6-kb fragment has a third copy, suggesting that rabbit I has three different C beta genes. The DNA sequence of a germ-line genomic DNA fragment encoding the first exon of the beta-chain constant region from rabbit I also has an open reading frame encoding 140 amino acids immediately 5' of the C beta sequence. A corresponding sequence had previously been found in a cDNA clone from the second rabbit (rabbit II).

Alleles↗
PubMed1987

A cluster of rabbit T-cell beta-chain variable region genes.

A genomic Eco RI DNA fragment of 4291 base pairs contains three V beta genes (V44T0, V44T1, and V44T2), each represented as only a single copy in the haploid genome of the rabbit. These V beta do not appear to be pseudogenes; all three can be found on approximately 1.3 kb (mature size) transcripts in thymus RNA, although they do not contain classical upstream promoter sequences. V beta T0 and T1 exhibit high DNA sequence homologies with mouse V beta 10 and V beta 1 genes, respectively (approximately 81 and 73%). In the mouse, the two genes are also closely linked. Rabbit V beta gene T2 resembles mouse V beta 11 and human YT35 DNA sequences but the homologies are lower (approximately 63%). The deduced protein sequences of the rabbit and mouse gene pairs are also conserved and ratios of replacement changes to silent base changes are low, suggesting that there has been selection for conservation of certain portions of the protein sequences. In contrast, the DNA and deduced protein sequences of the adjacent closely linked rabbit V beta genes are remarkably different from each other (approximately 54-65% DNA; approximately 33-55% protein homologies). These facts suggest early duplication of V beta genes and evolutionary conservation of certain members.

Amino Acid Sequence↗
PubMed1987

Evolution of genes for allelic and isotypic forms of immunoglobulin kappa chains and of the genes for T-cell receptor beta chains in rabbits.

New insights into the evolution of the families of genes encoding immunoglobulins and T-cell receptors of rabbits (Oryctolagus cuniculus) have come from molecular genetic studies. In contrast to human and mouse, rabbits were shown to have two genes for the constant region of immunoglobulin light chains (C kappa 1 and C kappa 2 isotypes) and complex allelic variants of K1 (allotypes). Although K1 allotype protein sequences differed at up to 41% of the amino acid positions, 3' untranslated, 5', and 3' flanking regions were conserved, and in the coding regions 78-80% of the codons with differences had replacement changes. Proportions of silent changes and changes in noncoding regions were comparable. Thus, in spite of their markedly different protein sequences, the K1b4, b5, and b9 allotypes appeared to be products of allelic genes. Molecular genetic analyses suggested that they may have undergone rapid divergence after an ancestral K2-like gene duplicated. Some rabbits were found to have two similar T-cell receptor C beta genes as do humans and many strains of mice, but others appeared to have three different C beta. In addition, we found allotypic forms of C beta. Some of the C beta allotypic differences occurred at positions where analogous C kappa allotypic differences were found. We also found V beta in mouse and human that were more similar to rabbit V beta than closely linked rabbit genes were to each other. This contrasts with rabbit immunoglobulin VH gene sequences that reflect concerted evolution. The data suggested that T-cell receptor V beta genes duplicated prior to mammalian radiation.

Alleles↗