Cytotoxic activity and T cell receptor repertoire in tumor-infiltrating lymphocytes of adrenal cell carcinomas

The cytotoxic activity and T cell receptor (TCR) V repertoire in tumor-infiltrating lymphocytes (TIL) of three primary adrenal cell carcinomas were analyzed. Fresh, non-cultured TIL from two of the three tumors showed low but significant lysis of the autologous tumor, and for one of the patients this activity was strongly enhanced upon culture in interleukin-2. An allogeneic adrenal cell carcinoma line and the K562 or Daudi targets included as controls were not killed. Phenotypic analysis of freshly isolated TIL demonstrated that the cells from the two patients that demonstrated cytolytic capacity mainly consisted of CD45RO⁺ T cells. In vitro cultured TIL lines from these patients demonstrated a high percentage of CD8⁺ cells expressing either the V6 gene or the V8 gene product, as measured with a panel of mAb specific for TCR V and V gene products. Analysis of the TCR V gene mRNA expression in freshly isolated non-cultured TIL, using a polymerase-chain-reaction-assisted cDNA-amplification assay, confirmed the strong expression of the genes coding for the TCR V6 or the V8. This assay also demonstrated a more restricted TCR V gene usage in the TIL as compared to peripheral blood lymphocytes from the same patient.This study was supported by the Swedish Cancer Society and by the Cancer Society in Stockholm     

Allelic divergence in the human insulin gene provides evidence for intragenic recombination events in the non-coding regions: evidence for existence of new alleles

Intragenic polymorphism of the human insulin gene (INS) was investigated in Korean subjects. The 1.9 kb INS sequence, including the 5 to 3 flanking regions, was amplified using the polymerase chain reaction (PCR), and analyzed by direct sequencing. All nucleotide sequences in the coding regions were the same as INS sequences previously reported, and four nucleotides, at positions +216, +1045, +1367, and +1380 in the non-coding regions, were found to be polymorphic. In addition to the previously identified polymorphic alleles l (A-C-C-C) and 1 (T-G-T-A), new nucleotide arrangements were also identified and designated 4 (A-C-C-A), 5 (A-G-C-C), 6 (A-C-T-C), and 2 (T-C-C-C). It was concluded that the new alleles may originate by intragenic recombination within INS during chromosomal crossing-over between the 1 and 1 alleles. The allele 1 was the predominant form in our sample; the new variant alleles, as well as allele 1, appeared to be much less frequent in INSs genes of the Korean subjects studied. Furthermore, the new alleles were detected only in heterozygous form. These results suggest that intragenic recombination can account for allelic divergence in INS.     

Analysis of T cell receptor Vβ gene usage during the course of disease in patients with chronic hepatitis B

The T cell receptor (TCR) is a heterodimeric molecule expressed on the surface of T cells and recognizes foreign peptides presented by the major histocompatibility complex on the surface of antigen-presenting cells or virusinfected cells. Analysis of TCR usage by T cells which recognize hepatitis B virus (HBV) provides further insight into the participation of T cell populations during the course of disease. In this study, we examined the T-cell-proliferative response and the TCR V gene usage of peripheral blood mononuclear cells in 3 patients with clinical evidence typical of chronic hepatitis B. All 3 patients had significant T-cell proliferative responses against HBV core antigen (HBcAg) during the remission stage, while no responses were detected during the acute exacerbation stage. In addition, the TCR V₇ gene was utilized more frequently in T cells recognizing HBcAg during remission, while TCR V₁ and V₂ were utilized at a higher percentage during acute exacerbation. On the contrary, the T cell proliferative response against HBV surface antigen was undetectable and no specific V gene was utilized more frequently by all 3 patients, regardless of disease state. Our longitudinal studies, although based on a small sample of patients, demonstrate that the population of HBcAg-activated T cells alters during the course of disease in chronic hepatitis B patients.     

Erratum: Cloning and sequencing of the phycocyanin gene from Spirulina maxima and its evolutionary analysis

The genes were cloned for the two apoprotein subunits, and ,of phycocyanin from the cyanobacterium Spirulina maxima = Arthrospiramaxima) strain F3. The - and -subunit gene-coding regionscontain 489 bp and 519 bp, respectively. The -subunit gene is upstreamfrom the -subunit gene, with a 111-bp segment separating them.Similarities between the -subunits of S. maxima and nine othercyanobacteria were between 58% and 99%, as were those between the -subunits. The maximum similarity between the - and -subunits from S. maxima was 27%.     

Heterogeneity of the hemoglobin of the Ohrid trout (Salmo L. typicus)

We have analyzed the hemoglobins of five individual trout from the Ohrid Lake (Salmo L. typicus) by electrophoretic methods, by reversed-phase high-performance liquid chromatography, and by limited structural analyses. The two major classes of hemoglobin are type I (35% of total) and type IV (65%). Type IV is the major oxygen-transporting hemoglobin; it consists of three types of chain (in about equal quantities) and three types of chain (one major and two minor types). Several structural differences have been observed between these three (IV) chains and between the three (IV) chains, suggesting a complex genetic system governing the synthesis of these proteins. Moreover, a few amino acid substitutions occur at positions involved in contacts between chains, which suggests that differences in oxygen affinity may exist between these various type IV hemoglobins. Type I hemoglobin is less complex because it contains one type of chain and two chains; the latter two differ in numerous positions, suggesting duplications of the (I)-globin gene. The and chains of type I hemoglobin differ considerably from the and chains of type IV hemoglobin, indicating the existence of (I)- and (I)-globin genes separate from the (IV)- and (IV)- globin genes.This study was supported in part by the Yugoslav-American Joint Funds, pp 812 (to G.D.E.), and by United States Public Health Service Research Grant HLB-05168 (to T.H.J.H.).     

A structural model for elongation factor 1 (EF-1) and phosphorylation by protein kinase CKII

EF-1a binds aminoacyl-tRNA to the ribosome with the hydrolysis of GTP; the complex facilitates the exchange of GDP for GTP to initiate another round of elongation. To examine the subunit structure of EF-1 and phosphorylation by protein kinase CKII, recombinant , , and subunits from rabbit were expressed in E. coli and the subunits were reconstituted into partial and complete complexes and analyzed by gel filtration. To determine the availability of the and subunits for phosphorylation by CKII, the subunits and the reconstituted complexes were examined as substrates for CKII. Formation of the nucleotide exchange complex increased the rate of phosphorylation of the subunit and reduced the Km, while addition of to or the complex inhibited phosphorylation by CKII. However, a had little effect on phosphorylation of . Thus, the and subunits in EF-1 were differentially phosphorylated by CKII, in that phosphorylation of was altered by association with other subunits, while the site on was always available for phosphorylation by CKII. From the availability of the subunits for phosphorylation by CKII and the composition of the reconstituted partial and complete complexes, a model for the subunit structure of EF-1 consisting of (22)2 is proposed and discussed.     

Preparation of a series of sulfated tetrasaccharides from shark cartilage chondroitin sulfate D using testicular hyaluronidase and structure determination by 500 MHz1H NMR spectroscopy

Six tetrasaccharide fractions were isolated from shark cartilage chondroitin sulfate D by gel filtration chromatography followed by HPLC on an amine-bound silica column after exhaustive digestion with testicular hyaluronidase. Their structures were determined unambiguously by one- and two-dimensional 500 MHz¹H NMR spectroscopy in conjunction with HPLC analysis of chondroitinase AC-II digests of the tetrasaccharides. One fraction was found to contain two tetrasaccharide components. All the seven tetrasaccharides shared the common core structure GlcA1-3GalNAc1-4GlcA1-3GalNAc with various sulfation profiles. Four were disulfated comprising of two monosulfated disaccharide units GlcA1-3GalNAc(4-sulfate) and/or GlcA1-3GalNAc(6-sulfate), whereas the other three were hitherto unreported trisulfated tetrasaccharides containing a disulfated disaccharide unit GlcA(2-sulfate)1-3GalNAc(6-sulfate) and a monosulfated disaccharide unit GlcA1-3GalNAc(4-or 6-sulfate). These sulfated tetrasaccharides were demonstrated to serve as appropriate acceptor substrates for serum -N-acetylgalactosaminyltransferase, indicating their usefulness as authentic oligosaccharide substrates or probes for the glycobiology of sulfated glycosaminoglycans.Abbreviations NFU National formulary unit - COSY correlation spectroscopy - HOHAHA homonuclear Hartmann-Hahn - 1D or 2D one- or two-dimensional - IdoA l-iduronic acid - GlcA d-gluco-4-enepyranosyluronic acid - Di-0S GlcA1-3GalNAc - Di-4S GlcA1-3GalNAc(4-sulfate) - Di-4S GlcA1-3GalNAc(4-sulfate) - Di-6S GlcA1-3GalNAc(6-sulfate) - Di-6S GlcA1-3GalNAc(6-sulfate) - Di-diS _d GlcA(2-sulfate)1-3GalNAc(6-sulfate) - Di-diS_E GlcA1-3GalNAc(4, 6-disulfate) - U G, U, 2S, 4S, and 6S represent GlcA, GalNAc, GlcA, 2-O-sulfate, 4-O-sulfate, and 6-O-sulfate, respectively     

Immunohistological analyses of neutral glycosphingolipids and gangliosides in normal mouse skeletal muscle and in mice with neuromuscular diseases

The expression of neutral glycosphingolipids (GSLs) and gangliosides was investigated in cryosections of normal mouse skeletal muscle and in muscle of mice with neuromuscular diseases using indirect immunofluorescence microscopy. Transversal and longitudinal sections were immunostained with specific polyclonal antibodies against lactosylceramide, lacto-N-neotetraosylceramide, globoside, G_M3(Neu5Ac), G_M3(Neu5Gc) and G_M1(Neu5Ac) as well as monoclonal anti-Forssman GSL antibody. In normal CBA/J mouse muscle (control) the main immunohistochemically detected ganglioside was G_M3(Neu5Ac) followed by moderately expressed G_M3(Neu5Gc) and G_M1. The neutral GSLs lactosylceramide and globoside were stained with almost identical, high fluorescence intensity. Low amounts of lacto-N-neotetraosylceramide and trace quantities of Forssman GSL were immunostained. All GSLs were detected in the sarcolemma, but also in considerable amounts at the intracellular level. Mice with neuromuscular diseases were the A2G-adr mouse mutant (a model for human recessive myotonia of Becker type), the BL6-wr mutant (a model for motor neuron disease) and the BL10-mdx mouse mutant (a model for human Duchenne muscular dystrophy). No changes in GSL expression were found in the A2G-adr mouse, while muscle of the BL6-wr mouse showed increased intensity of immunofluorescence in stainings with anti-lactosylceramide and anti-G_M3(Neu5Ac) antibodies. Muscle of BL10-mdx mice showed the most prominent changes in GSL expression with reduced fluorescence intensity for all antibodies. Major differences were not observed in the intensities of GSLs, but there were significant differences in the patterns of distribution on plasma membrane and at the subcellular level. The exact nature and pathogenesis of these changes should be elucidated since such investigations could furnish advances in understanding the functional role of neutral GSLs and gangliosides in normal as well as in diseased muscle. Abbreviations: BSA, bovine serum albumin; DAPI, 4, 6-diamidine-2-phenylindole-dihydrochloride; DTAF, dichlorotriazinylamino-fluorescein; GSL(s), glycosphingolipid(s); Neu5Ac,N-acetylneuraminic acid; Neu5Gc,N-glycolylneuraminic acid [53]; PBS, phosphate buffered saline. The designation of the following glycosphingolipids follows the IUPAC-IUB recommendations [54] and the nomenclature of Svennerholm [55]. Lactosylceramide or LacCer, Gal1-4Glc1-1Cer; gangliotriaosylceramide or GgOse₃Cer, GalNAc1-4Gal1-4Glc1-1Cer; globotriaosylceramide or GbOse₃Cer, Gal1-4Gal1-4Glc1-1Cer; gangliotetraosylceramide or GgOse₃Cer, Gal1-3GalNAc1-4Gal1-4Glc1-1Cer; globotetraosylceramide or GbOse₄Cer, GalNAc1-3Gal1-4Gal1-4Glc1-1Cer; lacto-N-neotetraosylceramide or nLcOse₄Cer, Gal1-4GlcNAc1-3Gal1-4Glc1-1Cer; Forssman GSL or GbOse₅Cer, GalNAc1-3GalNAc1-3GAl1-4Gal1-4Glc1-1Cer; G_M3, II³Neu5Ac-LacCer; G_M1, II³Neu5Ac-GgOse₄Cer.     

Regioselective deacetylation of peracetylated monosaccharide derivatives by polyethylene glycol-modified lipase for the oligosaccharide synthesis

Lipase modified with polyethylene glycol became soluble and active in organic solvents, and catalyzed regioselective deacetylation of peracetylated monosaccharide derivatives in 1,1,1-trichloroethane. The deacetylation occurred only at the positions of C-4 and C-6 of the glycopyranoside ring. Especially, peracetylated methyl -D-xylopyranoside and peracetylated L-serine--D-xylopyranoside were hydrolyzed only at the position of C-4. Subsequently, one of the resulting products, that is L-serine-2,3-di-O-acetyl--D-xylopyranoside, was coupled with galactose residue to obtain L-serine-4-O-(-D-galactopyranosyl)--D-xylopyranoside, a model compound of the carbohydrate-protein linkage region of proteoglycans.     

Correlation between the Vß4+CD8+ T-cell population and theH-2 d haplotype

The Vß4 ⁺ T-cell population was examined with a newly established antibody, KT4, specific for Vß4. Between 4.8% and 19.4% of CD3⁺ peripheral T cells from various inbred strains of mice or Fl hybrids expressed Vß4. The CD4 T-cell population had higher numbers of V4⁺ T cells (5.5%–20.6%) than the CD8 T-cell population (2.5%–10.7%). Deletion of certain Vexpressing T cells due to the presence of the Mls^a antigen and/or the absence of certainTcrb-V genes increased relative numbers of Vß4⁺ T cells. The data suggest that V4⁺ CD8⁺ T cells might be positively selected by H-2^d molecules.     

Protein kinase C β from Friend erythroleukemia cells is associated with chromatin and DNA

Certain protein kinase C (PKC) isotypes are localized to the nucleus during cellular proliferation in murine erythroid cells, as well as in human promyelocytic leukemia and erythroleukemia cells. Because the structure of these PKC isotypes contains a conserved cysteine-rich region that contains the zinc finger DNA binding motif, we tested the hypothesis that selected PKC isotypes found in Friend erythroleukemia cells can bind to DNA. Cell lysates from murine Friend erythroleukemia cells, which express , I, and II PKC, expressed greater amounts of the isoforms than the isoform of PKC in their nuclei, and PKC I was found in the chromatin of these cells. Lysates of these cells were tested for their ability to bind to a DNA-cellulose columm. Bound proteins were eluted with a step gradient of increasing KCl concentrations, and eluant fractions were then subjected to immunoblot analysis using isotype-specific antibodies to the and I isotypes of PKC. DNA binding was detected for the PKC I isotype, which is present in the nucleus, but not for the more abundant PKC isotype, which resides primarily in the cytoplasm. These results demonstrate that PKC can associate with DNA, and that this association is isotype specific in Friend erythroleukemia cells. (Mol Cell Biochem151: 107–111, 1995)     

T-cell receptor-specific monoclonal antibodies against a V β 11-positive mouse T-cell clone

Two monoclonal antibodies specific for the mouse T-cell receptor (Tcr) have been established by immunization with a V 11⁺ T-cell clone, clone C6. One is a rat antibody, KT11 (IgG2b, k), specific for the V chain of C6, V 11. This was demonstrated by the fact that the strain distribution pattern of KT11⁺ cells was similar to that of V 5, 8, 9, 11, 12, and 13 and that the gene that encodes the molecule detected by KT11 was closely linked to V 8 in (B10 × SJL)F₁ × SJL backcross mice. Furthermore, V of C6 has been cloned from a gt10 cDNA library and was demonstrated to be identical to the V 11 published sequences. All strains of mice that do not express major histocompatibility complex class II E molecules had higher numbers of KT11^– cells than E⁺ strains. The KT11⁺ population in A strain mice and its H-2 congenic strains, however, was not affected by the presence or absence of E molecules. The other is a mouse antibody, KTL2 (IgM), specific for the idiotope of the Tcr expressed on the clone C6. Both antibodies were mitogenic and induced cytotoxicity. Expression of epitopes detected by KT11 or KTL2 was down-modulated by a T3-specific antibody 145-2C11.     

Anti-(transforming growth factor β) antibodies with predefined specificity inhibit metastasis of highly tumorigenic human xenotransplants in nu/nu mice

Monoclonal antibodies (mAb) were prepared against conjugated transforming growth factor 1 (TGF1) peptides: amino acid positions 48–60 and positions 86–101. Two antibodies, mAb 16-3G1 [anti-(48–60)] and mAb 5-2G6 [anti-(86–101)] cross-reacted with native TGF1,-2 and-3 (16-3G1) or only with native TGF1 (5-2G6). Both mAb were used to characterize TGF-mediated effects on the metastatic potential in nude mice of human carcinoma cell line SLU-1 and its metastatic subline SLU-M1. Autocrine TGF1-mediated up-regulation of cell proliferation and its suppression by anti-TGF antibodies in vitro was recorded for SLU-M1 cells whereas SLU-1 cell proliferation in vitro appeared to be refractory to anti-TGF antibodies and exogenous TGF-1. However, the potential of s.c. tumours to develop distant metastases in nude mice was about the same for both cell lines. Development of primary tumours and distant metastases could be suppressed by treatment of mice with anti-TGF antibodies. Thus we assume that the metastatic potential of tumour cells is independent of TGF-mediated growth-regulation effects in vitro. The anti-TGF-induced suppression of tumour progression and metastasis in nude mice might rather result from stimulation of the immune surveillance. TGF-mediated autocrine down-regulation of MHC-unrestricted cytotoxicity of activated human monocytes and CD56⁺ LAK cells and its reversion by anti-TGF antibodies could be readily demonstrated. In all our experimental series, the neutralizing potential of both anti-TGF antibodies, though directed against opposite sites of the TGF1 molecule, was very similar.     

Flavonglykoside in Blüten vonPaeonia arborea undPaeonia suffruticosa

Summary Three glycosides have been isolated fromPaeonia arborea: kaempferol-3--glucoside-7--glucoside (Paeonoside), apigenin-7--glucoside, and apigenin-7-rhamnoglucoside (Rhoifolin).Paeonia suffruticosa also contains these three compounds but its main glycoside is kaempferol-3--glucoside (astragalin), which is present inPaeonia arborea only in traces.     

Structure and evolution of the HLA Class II SXβ gene

The class II major histocompatibility complex antigens are cell-surface heterodimers consisting of an a and a chain. Cosmid cloning has shown that the three families of clas II antigens, DR, DQ, and DP, are encoded within the HLA-D region of chromosome 6 as a series of discrete gene clusters. The DP cluster contains two pairs of a and genes, one of which encodes the biochemically-defined DP antigen. In order to assess whether the other two genes, SXa and SX, are also expressed, potential coding regions have been subcloned and sequenced. The SX3 gene is shown to contain region closely homologous to all six exons of DP. A 1 bp deletion in the 2 exon, also observed for the SX4 allele, causes a translation frameshift, suggesting that SX is a pseudogene. However, all the other exons, as well as their splice sites and the putative promoter region, appear to be intact.     

Brain β-Amyloid Accumulation in Transgenic Mice Expressing Mutant Superoxide Dismutase 1

Oxidative stress is implicated in both the deposition and pathogenesis of -amyloid (A) protein in Alzheimers disease (AD). Accordingly, overexpression of the antioxidant enzyme superoxide dismutase 1 (SOD1) in neuronal cells and transgenic AD mice reduces A toxicity and accumulation. In contrast, mutations in SOD1 associated with amyotrophic lateral sclerosis (ALS) confer enhanced pro-oxidative enzyme activities. We therefore examined whether ALS-linked mutant SOD1 overexpression in motor neuronal cells or transgenic ALS mice modulates A toxicity or its accumulation in the brain. Aggregated, but not freshly solubilised, substrate-bound A peptides induced degenerative morphology and cytotoxicity in motor neuron-like NSC-34 cells. Transfection of NSC-34 cells with human wild-type SOD1 attenuated A-induced toxicity, however this neuroprotective effect was also observed for ALS-linked mutant SOD1. Analysis of the cerebral cortex, brainstem, cerebellum and olfactory bulb from transgenic SOD1^G93A mice using enzyme-linked immunosorbent assay of acid–guanidine extracts revealed age-dependent elevations in A levels, although not significantly different from wild-type mouse brain. In addition, brain amyloid protein precursor (APP) levels remained unaltered as a consequence of mutant SOD1 expression. We therefore conclude that mutant SOD1 overexpression promotes neither A toxicity nor brain accumulation in these ALS models.     

Ein fluoreszenzmikroskopischer Nachweis von β-Glucosidase in Wurzeln vonCicer arietinum (L.)

Zusammenfassung Die Lokalisierung von -Glucosidasen in Wurzeln der Kichererbse [Cicer arietinum (L.)] wurde in einem einstufigen fluoreszenz-optischen Verfahren mit 4-Methyl-umbelliferyl-D-glucosid untersucht. Am Beispiel der Kichererbse wird gezeigt, daß in polyphenolhaltigen Pflanzen herkömmliche Azokupplungsverfahren zur Glucosidaselokalisierung nicht anwendbar sind. Die mit der neuen Methode erhaltenen Ergebnisse decken sich im wesentlichen mit denen aus vergleichbaren Untersuchungen und zeigen, daß -Glucosidasen nicht vorhanden sind. Aryl--Glucosidasen wurden vorwiegend im äußeren Cortexbereich gefunden und nehmen mengenmäßig zur Wurzelspitze hin zu.

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Localization of -glucosidase in roots ofCicer arietinum (L.) by a fluorescence technique

Summary The localization of -glucosidases in roots of garbanzo beans [Cicer arietinum (L.)] has been investigated by a one-step fluorescence optical procedure using 4-methylumbelliferyl--D-glucoside. It is shown that the well known azo-coupling test for the localization of glucosidases cannot be applied in polyphenol containing plants. The results obtained with the new method are comparable with those described in other investigations and further show that -glucosidases are absent from the root tissues investigated. The aryl--glucosidases were mainly detected in the outer region of the cortex and quantitatively increase towards the root tip.

     

Qualitative and quantitative composition of pigments in Phaeodactylum tricornutum (Bacillariophyceae) stressed by iron

The effect of Fe(III) deficiency on qualitative and quantitative changes in pigment composition in Phaeodactylum tricornutum Bohlin was demonstrated by HPLC and AAS. Maximum content of pigments showed the diatom cells incubated at the optimum iron concentration, i.e., 10 M. The contents of chlorophyll a, chlorophyll c ₁+c ₂, fucoxanthin, diadinoxanthin and ,-carotene were 109.99, 20.16, 40.39, 1.29 and 1.48 fg per cell, respectively. The results obtained showed that Fe(III) affected qualitative and quantitative pigment composition in P. tricornutum. The content of individual pigments, proportions between accompanying pigments and their ratios to chlorophyll a were important indicators of phytoplankton response to iron stress. The strong reduction in ,-carotene content, several times (2–5) increase in diadinoxanthin level as compared to ,-carotene, and high amount of diadinoxanthin in relation to chlorophyll a were observed in algae growing at very low Fe(III) concentrations, 0.001 and 0.01 M. The data suggested that phytoplankton pigments could be a potential physiological marker.     

Orientation of the porphyrin ring in artificial chlorophyll membranes

Summary A sensitive photometric method is described by which the dichroism of lipid bilayer membranes in aqueous phase can be measured. The method is applied to black films with incorporated chlorophylla andb. With chlorophylla a relatively large dichroism is found in the Soret band and a much weaker dichroism in the red band. From the experimental data, the angles _B and _R between the blue and red transition moments and the membrane can be obtained. _B and _R are then used to calculate the angle of the porphyrin ring with respect to the membrane surface. For chlorophylla and three different lipids, values of between 44 and 49° are found.     

Stimulation and inhibition of cardiac myocyte proliferation in vitro

Summary We have examined the effect of crude cardiac tissue extracts as well as that of several growth factors and triiodothyronin (T3) on DNA synthesis of cardiac myocytes in culture. Extracts from embryonic and adult cardiac tissue stimulated DNA synthesis of myocytes. Atrial myocytes exhibited overall higher degree of stimulation than their ventricular counterparts and extracts from adult atrial tissue had the highest apparent mitogenic activity for atrial myocytes. We have shown that adult heart contains basic fibroblast growth factor (bFGF), especially in the atria [1]. Transforming growth factor (TGF) and insulin-like growth factors (IGFs) are also accumulated in cardiac tissues [2, 3]. We found that bFGF and the IGFs stimulate myocyte cell proliferation and DNA synthesis. These factors also stimulate cardiac non-muscle proliferation, especially in the presence of serum. TGF inhibited proliferation and DNA synthesis and cancelled the effect of bFGF or IGFs on the myocytes. T3 also diminished the bFGF-induced mitogenic stimulation of cardiomyocytes. Our data suggest that these factors may be involved in the regulation of cardiomyocyte proliferation in vivo.Abbreviations bFGF basic Fibroblast Growth Factor - BSA Bovine Serum Albumin - DM Defined Medium - Fes Fetal calf serum - FITC Fluorescein - IGF Insulin-like Growth Factor - IgG Immunoglobulin - LI Labeling Index - PBS Phosphate Buffered Saline - T3 Triiodothyronine - TGF Transforming Growth Factor