Durable recovery of the macular architecture and functionality of a diagnosed age-related macular degeneration 1 year after a single intravitreal injection of dobesilate

Among the age-related diseases that affect vision, age-related macular degeneration is the most frequent cause of blindness in patients older than 60 years. In this communication, we report the full anatomical and functional recovery of a patient diagnosed with wet age-related macular degeneration 1 year after a single intravitreal injection of dobesilate.

Treatment of dry age-related macular degeneration with dobesilate

The authors present anatomical and functional evidences of dry age-macular degeneration improvement, after intravitreal treatment with dobesilate. Main outcomes measures were normalisation of retinal structure and function, assessed by optical coherence tomography, fundus-monitored microperimetry, electrophysiology and visual acuity. The effect might be related to the normalisation of the outer retinal architecture.

Topical treatment of actinic keratoses with potassium dobesilate 5% cream. a preliminary open-label study

BACKGROUND

Fibroblast growth factor (FGF) is involved in skin tumorigenesis: it promotes cell viability, induces angiogenesis and stimulates invasiveness. Dobesilate is a drug that blocks the activity of FGF. The primary objective was to evaluate the efficacy and tolerability of potassium dobesilate 5% cream in the treatment of actinic keratoses.

METHODS

Potassium dobesilate 5% cream was applied twice daily for 16 weeks to actinic keratosis lesions in 30 patients. The lesions were evaluated clinically at an initial baseline visit, at intermediate visits, and at 16 weeks of treatment. -

RESULTS

The use of potassium dobesilate 5% cream for 16 weeks induced complete regression in 70% of evaluated actinic keratoses, corresponding to grade I, II and III clinical variants, and a partial response (at least 75% reduction of lesions) in 20% of the cases.

CONCLUSION

Our preliminary trial shows that potassium dobesilate exerts anti-tumorigenic effects and may play a useful role in the chemoprevention of skin cancers.

Dobesilate diminishes activation of the mitogen-activated protein kinase ERK1/2 in glioma cells

Fibroblast growth factors (FGFs) and their receptors, regularly expressed at high levels in gliomas, are further upregulated during the transition of the tumor from low- to high-grade malignancy, and are essential for glioma progression. FGFs induce upregulation of the mitogen-activated protein kinase (MAPK) signaling cascade in cultured glioma cells, which suggests that MAPK pathway participates in the FGF-dependent glioma development. Recently, it has been shown that dobesilate, an inhibitor of FGF mitogenic activity, shows antiproliferative and proapoptotic activities in glioma cell cultures. Accordingly, it should be expected this new synthetic FGF inhibitor to affect the activation levels of MAPK. Here we report that immunocytochemical and Western blot data unequivocally show that treatment of cell cultures with dobesilate causes a significant decrease of the intracellular levels of ERK1/2 activation, one of the components of the MAPK signalling cascade. This finding supports an important role for dobesilate in glioma growth, suggesting that dobesilate should be a treatment to be born in mind for glioma management.

Dobesilate inhibits the activation of signal transducer and activator of transcription 3, and the expression of cyclin D1 and bcl-XL in glioma cells

OBJECTIVES

Because fibroblast growth factor (FGF) causes the intracellular accumulation of activated signal transducer and activator of transcription 3 (STAT3), we assessed whether dobesilate, a synthetic FGF inhibitor that has been reported to show antiproliferative and proapoptotic activities in glioma cell cultures, down-regulates the STAT3 signaling pathway in growing cultures of those cells. Because STAT3 signaling pathway plays pleiotropic roles in tumor proliferation, maintenance of STAT3 in its inactive state may prevent glioma growth and spreading.

METHODS

Rat glioma C6 cells were treated with dobesilate and cultures were evaluated immunocytochemically for STAT3 activation and enhancement of the expression rate of cyclin D1 and bcl-XL.

RESULTS

Dobesilate abrogates the accumulation of activated STAT3 in glioma cells. The decrease in the intracellular levels of activated STAT3 by the dobesilate treatment runs parallel with a significant attenuation of cyclin D1 and bcl-XL expression.

CONCLUSION

Treatment with inhibitors of FGF down-regulates the STAT3 signaling pathway. These alterations could be correlated to the already observed inhibition of cell proliferation and promotion of apoptosis in glioma cell cultures by dobesilate. The reported results may open new avenues for developing new treatments against these tumors.

Dihydroxy-2,5 benzenesulphonate (dobesilate) elicits growth arrest and apoptosis in glioma cells

OBJECTIVES

Dihydroxy-2,5 benzenesulphonate (dobesilate) is used as an oral agent for treatment of vascular complications of diabetic retinopathy. We previously showed that blockade of fibroblast growth factor (FGF) driving angiogenesis with dobesilate inhibited new blood vessel formation in a mouse gelatine plug assay. In the present study we assessed the effects of dobesilate in rat glioma cells.

METHODS

Rat C6 cells line were grown as adherent cells in Dulbecco modified Eagle medium supplemented with 1% (v/v) fetal bovine serum and antibiotics. Calcium dobesilate was added in independent experiments at the following concentrations: 10, 25, 50, 75 and 100 microM, and cells were incubated for 24 hours. Effects of dobesilate in glioma cell proliferation and survival were assessed using crystal violet staining and TUNEL assay, respectively.

RESULTS

Incubation of glioma cells with dobesilate for 24 hours concentration-dependently decreased cell proliferation with an apparent IC50 of 25 microM, and this antiproliferative effect was related to a significant increase in glioma cell apoptosis.

CONCLUSIONS

The results suggest that dobesilate is a promising candidate leading to the development of a new adjuvant therapeutic strategy for gliomas.

A novel solenoid fold in the cell wall anchoring domain of the pneumococcal virulence factor LytA

Choline binding proteins are virulence determinants present in several Gram-positive bacteria. Because anchorage of these proteins to the cell wall through their choline binding domain is essential for bacterial virulence, their release from the cell surface is considered a powerful target for a weapon against these pathogens. The first crystal structure of a choline binding domain, from the toxin-releasing enzyme pneumococcal major autolysin (LytA), reveals a novel solenoid fold consisting exclusively of beta-hairpins that stack to form a left-handed superhelix. This unique structure is maintained by choline molecules at the hydrophobic interface of consecutive hairpins and may be present in other choline binding proteins that share high homology to the repeated motif of the domain.

Solution structure and interaction with basic and acidic fibroblast growth factor of a 3-kDa human platelet factor-4 fragment with antiangiogenic activity

Platelet factor-4 is a protein belonging to the family of ELR-negative CXC chemokines which binds to fibroblast growth factor and inhibits its mitogenic activity. Platelet factor-4 also inhibits tumor growth by mechanisms involving antiangiogenesis. Antiangiogenic activity in vitro has also been shown for the 24-residue C-terminal fragment of the protein, which decreases the affinity between basic fibroblast growth factor and its cell-surface receptor. In this study, the preferential conformation of this fragment in solution has been determined and has been found to be composed of two helical subdomains. In addition, we show that the fragment forms a specific 1:1 complex with acidic and basic fibroblast growth factors and that both subdomains are probably required for inhibition of fibroblast growth factor-driven mitogenesis. Finally, we show that the binding of the fragment alters the structure of the fibroblast growth factors, although some of such alterations do not seem related with the inhibition of mitogenic activity. Since this fragment has recently been shown to inhibit fibroblast growth factor-induced angiogenesis in vivo when injected intraperitoneally, these results are relevant for developing new antiangiogenic treatments.

The activation of fibroblast growth factors by heparin: synthesis, structure, and biological activity of heparin-like oligosaccharides

An effective strategy has been designed for the synthesis of oligosaccharides of different sizes structurally related to the regular region of heparin; this is illustrated by the preparation of hexasaccharide 1 and octasaccharide 2. This synthetic strategy provides the oligosaccharide sequence containing a D-glucosamine unit at the nonreducing end that is not available either by enzymatic or chemical degradation of heparin. It may permit, after slight modifications, the preparation of oligosaccharide fragments with different charge distribution as well. NMR spectroscopy and molecular dynamics simulations have shown that the overall structure of 1 in solution is a stable right-hand helix with four residues per turn. Hexasaccharide 1 and, most likely, octasaccharide 2 are, therefore, chemically well-defined structural models of naturally occurring heparin-like oligosaccharides for use in binding and biological activity studies. Both compounds 1 and 2 induce the mitogenic activity of acid fibroblast growth factor (FGF1), with the half-maximum activating concentration of 2 being equivalent to that of heparin. Sedimentation equilibrium analysis with compound 2 suggests that heparin-induced FGF1 dimerization is not an absolute requirement for biological activity.

Sequence analysis of heparan sulfate epitopes with graded affinities for fibroblast growth factors 1 and 2

Proteins that belong to the fibroblast growth factor (FGF) family regulate proliferation, migration, and differentiation of many cell types. Several FGFs, including the prototype factors FGF-1 and FGF-2, depend on interactions with heparan sulfate (HS) proteoglycans for activity. We have assessed tissue-derived HS fragments for binding to FGF-1 and FGF-2 to identify the authentic saccharide motifs required for interactions. Sequence information on a range of N-sulfated HS octasaccharides spanning from low to high affinity for FGF-1 was obtained. All octasaccharides with high affinity for FGF-1 (> or =0.5 m NaCl required for elution) contained an internal IdoUA(2-OSO(3))-GlcNSO(3)(6-OSO(3))-IdoUA(2-OSO(3))-trisaccharide motif. Octasaccharides with a higher overall degree of sulfation but lacking the specific trisaccharide motif showed lower affinity for FGF-1. FGF-2 was shown to bind to a mono-O-sulfated HS 6-mer carrying a single internal IdoUA(2-OSO(3))-unit. However, a di-O-sulfated -IdoUA(2-OSO(3))-GlcNSO(3)-IdoUA(2-OSO(3))-trisaccharide sequence within a HS 8-mer gave stronger binding. These findings show that not only the number but also the positions of individual sulfate groups determine affinity of HS for FGFs. Our findings support the notion that FGF-dependent processes can be modulated in vivo by regulated expression of distinct HS sequences.

Abolished angiogenicity and tumorigenicity of rat glioma by 1-naphthalenemonosulfonate

Suramins and suradistas, an important group of potential anti-cancer agents, inhibit fibroblast growth factor (FGF) mitogenic activity. It has been shown that naphthalenesulfonates, with a common chemical function to the family of suramins and suradistas, mimic their inhibitory activity, abolishing FGF-induced angiogenesis in vivo, and inducing apoptosis of C6 glioma cells in culture. In the present report, we show that intratumoral administration of 1-naphthalenemonosulfonate induces a considerable regression of gliomas in rats, significantly enhances apoptosis, and attenuates tumor angiogenesis. These findings may lead to new approaches for the treatment of glioblastoma, a most common primary malignant brain tumor of very poor prognosis, as well as of other angiogenesis-dependent malignancies.

Myo-inositol hexasulphate and low molecular weight heparin binding to human acidic fibroblast growth factor: a calorimetric and FTIR study

The interaction of an amino-terminal-truncated 139 amino-acids form of human acidic fibroblast growth factor with myo-inositol hexasulphate and low molecular weight (3500 g mol(-1)) heparin has been studied by isothermal titration calorimetry, differential scanning calorimetry and Fourier transform infrared spectroscopy. A slightly higher affinity for the monosaccharide has been measured. The binding of the ligands causes an increase of 13--15 degrees C in the melting temperature of the free protein (45 degrees C). From measured enthalpy and heat capacity changes, calculations of changes in accessible surface areas have been made. These calculations, together with infrared spectroscopy data, indicate that a small conformational change is induced by the binding of both ligands. This conformational change would affect the tertiary structure, not the secondary one.

Fibroblast growth factors in myocardial ischemia / reperfusion injury and ischemic preconditioning

Angiogenic growth factors such as fibroblast growth factors (FGFs) are currently in clinical trials for accelerating blood vessel formation in myocardial and limb ischemic conditions. However, recent experimental evidence suggests that FGFs can also participate as endogenous cardioprotective agents. In this report, the current knowledge for FGFs implication in myocardial ischemic tolerance will be summarized. Pharmacologic preconditioning with drugs as FGFs that mimic the beneficial effects of ischemic preconditioning could lead to novel therapeutic approaches for the treatment of ischemic disorders including myocardial infarction and stroke.

Acidic fibroblast growth factor inhibits junctional communication of Schwann cells in culture

The effect of acidic fibroblast growth factor (aFGF) was investigated on junctional communication of rat Schwann cells (SC) in culture. As measured by dye transfer, the incidence of coupling between SC was very low during the phase of proliferation and increased slowly and progressively with time under culture conditions that induced the myelinating phenotype. Treatment with aFGF alone or in combination with heparin decreased markedly coupling between SC in both culture stages. The coupling inhibition was rapid, the earliest effects being apparent 5-15 min after addition of growth factor, and was transient with a slower recovery of coupling at 1-3 h. The uncoupling effect of aFGF could be prevented by an inhibitor of protein-tyrosine kinase. Addition of heparin to cultures decreased the most effective aFGF concentration by 100-fold, from 100 ng ml-1 to 1 ng ml-1. The dose-response curves exhibited a characteristic window-shape. The results suggest that FGF might be involved in the regulation of the junctional communication between rat SC via tyrosine kinases.

Energetics of myo-inositol hexasulfate binding to human acidic fibroblast growth factor effect of ionic strength and temperature

The binding of myo-inositol hexasulfate to an N-terminal truncated 132-amino-acid human acidic fibroblast growth factor form was studied by isothermal titration calorimetry. The technique yields values for the enthalpy change and equilibrium constant, from which the Gibbs energy and entropy change can also be calculated. Experiments in different buffers and pH values show that the proton balance in the reaction is negligible. Experiments at pH 7.0 in the presence of 0.2-0.6 M NaCl showed that the enthalpy and Gibbs energy changes parallel behaviour with ionic strength change, with values in the -21 to -11 kJ x mol(-1) range in the first case and in the -31 to -22 kJ x mol(-1) range in the second. No dependence of entropy on ionic strength was found, with a constant value of approximately 35 J x K(-1) x mol(-1) at all ionic strengths studied. The results can be interpreted in molecular terms by a model in which competitive binding of 3-4 chloride ions to the myo-inositol-binding site is assumed. Isothermal titration calorimetry was also performed at different temperatures and yielded a value of -142+/-13 J x K(-1) x mol(-1) for the heat-capacity change at pH 7.0 and 0.4 M NaCl. Using different parametric equations in the literature, changes on ligand binding in the range -100 to -200 A2 in solvent-accessible surface areas, both polar and apolar, were calculated from thermodynamic data. These values suggest a negligible overall conformational change in the protein when the ligand binds and agree closely with calculations performed with NMR structural data, in which it is shown that the most important negative change in total solvent-accessible surface area occurs in the amino acids Ile56, Gln57, Leu58 and Leu149, in the high-affinity receptor-binding region of the protein.

1H NMR structural characterization of a nonmitogenic, vasodilatory, ischemia-protector and neuromodulatory acidic fibroblast growth factor

A shortened genetically engineered form of acidic fibroblast growth factor (aFGF), that includes amino acids 28-154 of the full-length sequence (154 residues) plus Met in substitution of Leu27, does not induce cell division even though it is recognized by the cell membrane receptor, triggers the early mitogenic events, and retains the neuromodulatory, vasoactive, and cardio- and neuroprotective properties of the native full-length molecule. Taken together, these properties make this truncated aFGF a promising compound in the treatment of a wide assortment of neurological and cardiovascular pathologies where aFGF mitogenic activity is dispensable. Differences in biological activities between the shortened aFGF and the wild-type form have been attributed to lack of stability, and to the specific amino acid sequence missing at the N-terminus. Here we show that this shortened aFGF form has a three-dimensional structure even more stable than the wild-type protein at the mitogenic assay conditions; that this structure is similar to that of the wild type except at site 1 of interaction with the cell membrane receptor; that its lack of mitogenic activity cannot be attributed to the specific missing sequence; and that the vasodilatory activity of aFGF seems impaired by alterations of the three-dimensional structure of site 2 of interaction with the cell membrane receptor.

Partial IGF affinity of circulating N- and C-terminal fragments of human insulin-like growth factor binding protein-4 (IGFBP-4) and the disulfide bonding pattern of the C-terminal IGFBP-4 domain

Within the IGF axis, the insulin-like growth factor-binding proteins (IGFBPs) are known to play a pivotal role in cell proliferation and differentiation. Defined proteolysis of the IGFBPs is proposed to be an essential mechanism for regulating IGF bioavailability. The generated IGFBP fragments in part exhibit different IGF-dependent and -independent biological activities. Characterizing naturally occurring forms of IGFBPs in human plasma, we identified both a N- and a C-terminal fragment of IGFBP-4 by means of immunoreactivity screening. As a source for peptide isolation, we used large amounts of human hemofiltrate obtained from patients with chronic renal failure. Purification of the IGFBP-4 peptides from hemofiltrate was performed by consecutive cation-exchange and reverse-phase chromatographic steps. Mass spectrometric and sequence analysis revealed an M(r) of 13 233 for the purified N-terminal fragment spanning residues Asp(1)-Phe(122) of IGFBP-4 and an M(r) of 11 344 for the C-terminal fragment extending from Lys(136) to Glu(237). Proteolytic digestion and subsequent biochemical analysis showed that the six cysteines of the C-terminal IGFBP-4 fragment are linked between residues 153-183, 194-205, and 207-228 (disulfide bonding pattern, 1-2, 3-4, and 5-6). Plasmon resonance spectroscopy, ligand blot analysis, and saturation and displacement studies demonstrated a very low affinity of the C-terminal IGFBP-4 fragment for the IGFs (IGF-II, K(d) = 690 nM; IGF-I, K(d) > 60 nM), whereas the N-terminal fragment retained significant IGF binding properties (IGF-II, K(d) = 17 nM; IGF-I, K(d) = 5 nM). This study provides the first molecular characterization of circulating human IGFBP-4 fragments formed in vivo exhibiting an at least 5-fold decrease in the affinity of the N-terminal IGFBP-4 fragment for the IGFs and a very low IGF binding capacity of the C-terminal fragment.

Fibroblast growth factor cardioprotection against ischemia-reperfusion injury may involve K+ ATP channels

We investigated whether the adenosine triphosphate (ATP)-sensitive K+ (K+ATP) channel that was implicated in the ischemic preconditioning (I-PC) phenomenon, has a role in the cardioprotective effects of fibroblast growth factors (FGFs). For this purpose, we administered glibenclamide, a specific K+ATP channel blocker, before acidic fibroblast growth factor (aFGF, FGF-1) treatment, in rat heart subjected to left ventricular ischemia for 20 minutes followed by reperfusion for 24 hours. Creatine kinase (CK) activity was analyzed in myocardial tissue to assess the degree of cardiac injury. FGF-1 treatment markedly maintains CK activity. This cardioprotective effect of FGF-1 was blocked by glibenclamide. As shown by ultrastructural data, Ca2+ overload and associated cardiomyocyte alterations shown in glibenclamide-treated rats were not observed in specimens from the FGF-1 group. These findings suggest that FGF serves as an effector in I-PC and support a clinical interest of these proteins for increasing myocardial ischemic tolerance.

Fibroblast growth factor and hydrocephalus

The immunohistochemical localization of basic fibroblast growth factor (bFGF) was studied in ventricular ependyma and choroid plexus of aged-matched normotensive and spontaneously hypertensive rats at different ages using a polyclonal antibody against bFGF. The bFGF-like immunoreactivity was observed in brain ependyma and choroid plexus of young and old normotensive rats. However, a progressive loss of immunoreactivity was observed with age in spontaneously hypertensive rats, that was associated with a progressive cerebroventricular dilation. These results show a new neuroendocrine anomaly to be added to the many others previously observed in this rat strain, when they develop hydrocephalus as they age.

Cardioprotection from ischemia by fibroblast growth factor: role of inducible nitric oxide synthase

Growing evidence from both animal experiments and clinical observations indicates that fibroblast growth factor (FGF) plays a protective role in myocardial reperfusion injury. The molecular and cellular mechanisms that lead to this postischemic myocardial protection, however, remain largely unexplored. We studied the cardioprotective effects of human recombinant acidic fibroblast growth factor (aFGF, FGF-1) in a rat model of myocardial reperfusion injury, induced by 20 minutes of left coronary artery occlusion followed by 24 hours of reperfusion. Intravenous FGF-1 administration at the onset of heart reperfusion attenuated both the functional impairment and the histological changes of ischemia/reperfusion injury. FGF-1 increases more than twice the left ventricular contractile function (p <0.005) compared to vehicle-treated rats. As shown by histology, myocardial tissue is better preserved with FGF-1 treatment. The infarct size, normalized for the area at risk, was significantly smaller in the FGF-1 group (p <0.01) than in the vehicle group. Furthermore, FGF-1 administration resulted in expression of inducible nitric oxide synthase (iNOS) in the area at risk. Since increased expression of iNOS could potentiate cardioprotection against myocardial reperfusion injury, our findings support a new non-mitogenic role for FGF and add a clinical interest for this protein in increasing myocardial ischemic tolerance.

Apoptosis of glioma cells induced by the fibroblast growth factor inhibitor 1,3,6-naphthalenetrisulfonate

Fibroblast growth factors (FGFs) are powerful angiogenic polypeptides that are involved in the autocrine growth stimulation of gliomas. We report here that addition to glioma cell cultures of 1,3,6-naphthalenetrisulfonate (NTS), an inhibitor of the mitogenic activity of FGFs, significantly enhanced apoptosis, as assessed by terminal deoxynucleotidyl transferase (TdT) assay. The pro-apoptotic effect of NTS was time-dependent. These findings suggest that FGF may play a pivotal role in the survival of glioma cells, and support a clinical interest of NTS as a leading compound for the development of new antitumorals.

Common binding sites for beta-amyloid fibrils and fibroblast growth factor-2 in heparan sulfate from human cerebral cortex

Heparan sulfate found in the cerebral plaques of Alzheimer's disease binds to beta-amyloid (Abeta) fibrils. This interaction has been proposed to enhance fibril deposition and mediate Abeta-induced glia activation and neurotoxicity. On the other hand, heparan sulfate augments signaling of fibroblast growth factor-2 (FGF-2), a neuroprotective factor that antagonizes the neurotoxic effects of Abeta. We defined structures in heparan sulfate from human cerebral cortex that bind Abeta fibrils. The minimal binding site is found in N-sulfated hexasaccharide domains and contains critical 2-O-sulfated iduronic acid residues. By contrast, binding of Abeta monomers requires, in addition, 6-O-sulfate groups on glucosamine residues. The binding specificity of fibrillar Abeta is shared by FGF-2, and we here show that cerebral heparan sulfate domains selected for binding to Abeta-(1-40) fibrils bind also to FGF-2. These data suggest that neurotoxic and neuroprotective signals may converge by competing for the same binding sites on the heparan sulfate chain.

Fibroblast growth factor protects the kidney against ischemia-reperfusion injury

Ischemia-reperfusion injury, a common source of renal dysfunction in adults, is associated with tubular epithelial cell damage. Since fibroblast growth factors (FGF) attenuated tissue injury after transient myocardial ischemia, we hypothesized that acidic fibroblast growth factor (aFGF; FGF-1) would attenuate renal ischemia-reperfusion injury. We studied the effects of FGF-1 in a rat model of acute renal failure induced by bilateral renal ischemia (60 min) and 1, 2 or 7 days reperfusion. After FGF-1 administration at the onset of renal reperfusion, there was less functional impairment of the kidneys. The histological changes were not as severe as in controls. Increases in serum creatinine and blood urea nitrogen 24 h after reperfusion were attenuated by 35% (p< 0.01) and by 53% (p< 0.001), respectively, in FGF-1-treated animals compared to vehicle-treated rats. The ischemia/reperfusion-induced increase in tissue myeloperoxidase, a marker of neutrophil infiltration, was mitigated (67% reduction, p< 0.05) with FGF-1 treatment. As shown by histology, neutrophil infiltration and tubular cell necrosis in medulla were less pronounced (p< 0.0001 and p< 0.05, respectively) in animals receiving FGF-1. Furthermore, ischemia-induced apoptosis, prevalent in tubular cells of the cortex, was also attenuated by FGF-1-treatment (83% reduction, p< 0.0001). Pretreatment of animals with Nw-nitro-L-arginine (L-NNA), an inhibitor of nitric oxide synthase, abolished the attenuating effects of FGF-1 on neutrophil infiltration, suggesting that nitric oxide might participate in the anti-inflammatory effects of FGF-1 in this experimental design. Our data support a role for FGF-1 in attenuation of renal damage or failure after ischemia-reperfusion injury of the kidney, in part at least by inhibition of neutrophil infiltration.

Inhibition of intra-tumoral angiogenesis and glioma growth by the fibroblast growth factor inhibitor 1,3,6-naphthalenetrisulfonate

1,3,6-naphthalenetrisulfonate (NTS) can inhibit the proliferation in vitro of cells of various origin including glioma. We have studied the effects of NTS on intra-tumoral angiogenesis and tumor growth in the rabbit cornea after implantation of C6 rat glioma cells. It was found that neovascularization and glioma growth were abolished by topical administration of NTS. This effect could be mediated by both induction of programmed cell death and inhibition of growth, in endothelium and in tumor cells, most likely as a consequence of the disruption of the autocrine and paracrine effects of FGF released from endothelial and tumor cells. The results suggest that NTS is a promising candidate to lead the development of new angiogenesis inhibitors for the treatment of cancer and other diseases whose progression is dependent upon the development of new blood vessels.

Suppression of acidic fibroblast growth factor-dependent angiogenesis by the antigrowth activity of 1,3,6-naphthalenetrisulfonate

Growth factor-induced angiogenesis was studied using subcutaneously implanted gelatin sponges loaded with 10 mg ml-1 of acidic fibroblast growth factor (aFGF) in 20 micrograms ml-1 PBS heparin. The administration of 1,3,6-naphthalenetrisulfonate (NTS) directly into the sponge (20 mg ml-1) or intraperitoneally (200 mg kg-1) blocks invasion of the sponge by vasculature. Since angiogenesis is essential for tumor progression, the findings of the present study that NTS is an efficient inhibitor of neovascularization warrant further investigation of the potential clinical utility of this angiostatic agent for treating tumor growth and metastasis.

Systemic administration of acidic fibroblast growth factor ameliorates the ischemic injury of the retina in rats

The central neuroprotective effects against ischemic injury of fibroblast growth factor (FGF), administered either directly into the central nervous system or systemically, is well documented. Here we show in a rat model of transient retinal ischemia that the neuroprotective effect of systemically administered acidic fibroblast growth factor (aFGF, FGF-1) extends to the retina. Histological findings show a lower decrease of retinal ganglion cells and inner nuclear layer cells (P < 0.0001) in animals receiving FGF-1. These results suggest that FGF may function as a natural protection agent during transient retinal ischemia and further document that an efficient neuroprotection of central nervous tissues can be obtained by systemic administration of this protein. Our data may, thus, contribute to the development of novel and safe therapeutic approach for the treatment of the ischemic injury of the retina.

Solution structure of acidic fibroblast growth factor bound to 1,3, 6-naphthalenetrisulfonate: a minimal model for the anti-tumoral action of suramins and suradistas

Recent data show that anti-angiogenesis may provide a promising route to treat cancer. Fibroblast growth factors (FGFs) are powerful angiogenic polypeptides, whose mitogenic activity requires the presence of heparin-like compounds. It has been shown that angiogenesis promoted by FGFs on inhibition by monoclonal antibodies and antisense targeting can also inhibit tumour growth. Derivatives of suramin, a polysulfonated binaphthyl urea and binaphthylsulfonated derivatives of distamycin, suradistas, constitute an important group of potential anti-cancer agents. These compounds compete with heparin in forming tight complexes with FGFs. This inhibits the recognition of these growth factors by their tyrosine kinase membrane receptors thereby suppressing their angiogenic activity. Here we show that 1,3,6-naphthalenetrisulfonate, a common chemical function of the suramins and suradistas with the highest anti-angiogenic activity inhibits the mitogenic activity of acidic fibroblast growth factor, and that this inhibition is relieved by increasing concentrations of heparin in the assay. We have also solved the three-dimensional structure in solution of the protein complexed to this compound. The structural data provide clues that may help in understanding the inhibitory effect of suramins and suradistas, and could contribute to the development of new anti-tumoral drugs.

Acidic fibroblast growth factor rescues gerbil hippocampal neurons from ischemic apoptotic death

Neurotrophic factors have been shown to support the survival of injured neurons and promote their recovery. Here, we investigated whether acidic fibroblast growth factor (aFGF) could modify programmed cell death caused by transient forebrain ischemia in the gerbil. The data show that systemic administration of 2.6 microg aFGF after 5 min ischemia followed by 7 days of brain reperfusion significantly (p < 0.05) reduced the occurrence of apoptotic cell death in CA1 neurons. These data suggest that aFGF would contribute to brain protection after acute stroke.

Spasmolytic effect of acidic fibroblast growth factor in early cerebral vasospasm in the rat

BACKGROUND

In animal models of subarachnoid hemorrhage (SAH), basilar artery spasm has been described. Since fibroblast growth factors (FGFs) dilate rat basilar artery in vivo, we tested whether systemic administration of acidic fibroblast growth factor (aFGF) can reverse the basilar artery spasm following rat SAH.

METHODS

SAH was mimicked by injecting autologous blood into the cisterna magna. We used a digital substraction angiography system in order to evaluate the spasmolytic effect of aFGF administered via the axillary artery 7 minutes after the injection of the autologous blood. Control animals received vehicle solution in the same manner.

RESULTS

Intraarterial bolus injection of 2.6 micrograms aFGF, but not the solvent, reverses the acute basilar artery narrowing caused by SAH (23.05% of the baseline value at 5 minutes post-SAH).

CONCLUSIONS

Our results suggest an important role for FGFs in the cerebral tone regulation and support a clinical interest of FGFs in preventing cerebral ischemia following SAH, particularly if these vasoactive effects are added to the known neuroprotective effects of FGFs.

Intravenous fibroblast growth factor penetrates the blood-brain barrier and protects hippocampal neurons against ischemia-reperfusion injury

BACKGROUND

Fibroblast growth factors (FGFs) play a role in neuronal survival after brain ischemia when administered intrace-rebrally. However, the clinical problems that chronic intracerebral infusion of FGFs involves may restrict its use. The purpose of this study was to analyze if FGFs administered intravenously might afford neuroprotection against transient brain ischemia in the light of new published data that suggest that these polypeptides cross the blood brain-barrier (BBB).

METHODS

The efficacy of acidic fibroblast growth factor (aFGF) treatment was analyzed in a gerbil model of 5 min forebrain ischemia followed by 7 days of reperfusion. Native and nonmitogenic aFGF was injected in gerbils as a bolus through a jugular vein at the onset of reperfusion. Control animals received in the same manner vehicle solution alone. Seven days later, neuroprotection was evaluated histologically. Penetration of the FGF across the BBB was assessed by autoradiographic studies in rats. For that purpose, we injected through the jugular vein 0.1 microgram of uniformly labeled native 14C-basic fibroblast growth factor (bFGF), 0.1 microgram of heat-denatured 14C-bFGF, or a coinjection of 14C-bFGF with a 900-fold excess of unlabeled bFGF. Two hours later, animals were killed for morphological studies.

RESULTS

We report that a venous injection of either native or nonmitogenic form of aFGF after 5 min forebrain ischemia in the gerbil significantly reduced the occurrence of delayed neuronal death (DND) in the CA1 sector of the hippocampus. We also confirmed that blood-borne 14C-bFGF accumulates in CA1 pyramidal neurons.

Fibroblast growth factor-1 prevents myocardial apoptosis triggered by ischemia reperfusion injury

BACKGROUND

Apoptosis is a constant feature of reperfusion injury in ischemic cardiac myocytes, leading to late cell death. Since fibroblast growth factors (FGFs) inhibit apoptosis in differentiated cells, we hypothesized that FGF-1 (acidic FGF), in its native form, and a non-mitogenic isoform would attenuate myocardial ischemia-reperfusion- induced apoptosis.

METHODS AND RESULTS

The effect of native and non-mitogenic fibroblast growth factor-1 mutein (FGF-1 and m-FGF-1) on apoptosis assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) method was tested in a rat model of 20 min regional myocardial ischemia and 24h reperfusion. Myocardial ischemia followed by reperfusion resulted in a high myocardial apoptosis rate in the area at risk. When given as a systemic bolus inmediately after myocardial ischemia, both FGF-1 and m-FGF-1 significantly reduced apoptosis (by 60 and 61.2, respectively; p<0.0001).

CONCLUSIONS

The programed myocyte cell death triggered by ischemia-reperfusion injury is attenuated by FGF-1 in its native or non mitogenic isoforms, suggesting that this effect does not depend on the mitogenic properties of this protein. FGF-1 would contribute to the functional preservation of the myocardium after acute myocardial infarction.

Destabilization, oligomerization and inhibition of the mitogenic activity of acidic fibroblast-growth factor by aurintricarboxylic acid

The triphenylmethane derivative aurintricarboxylic acid has been used to inhibit angiogenesis, vascular smooth muscle cell proliferation and cell transformation, an effect that has been attributed to its relatively nonspecific inhibitory activity of protein-nucleic acid interactions. Here, we show that this compound binds to acidic fibroblast growth factor, a prototypic member of a family of protein mitogens activated by heparin, altering its physicochemical properties and decreasing its mitogenic activity. Counteraction of the effects of aurintricarboxylic acid by heparin shows that the two compounds have opposite and reversible effects on acidic fibroblast growth factor structure and biological activity. The studies reported here may contribute to a deeper understanding of the inhibition of fibroblast-growth-factor-dependent mitogenesis of relevance to future pharmacologic developments.

Kinins are implicated of the hypotensive effect of acidic fibroblast growth factor

Acidic fibroblast growth factor causes an acute and transient nitric oxide-dependent hypotensive effect in experimental animals. However, this response is not found, or is very small, in vitro. We hypothesized that plasma mediators, such as kinins, are involved in aFGF-induced hypotension. We studied the hypotensive effect of intravenous aFGF (1 microg) in control Wistar rats, and compared this response to that in Wistar rats treated with a bradykinin receptor antagonist Na-adamantaneacetyl-D-Arg-(Hyp3,Thi5,8,D-Phe7]-brad yki nin), in kininogen-deficient Brown-Norway-Katholiek (BNK) rats, and in rats depleted of kininogen after repeated treatment with ellagic acid. FGF was administered in the jugular vein and mean arterial pressure was measured through a femoral artery catheter. Following treatment with the bradykinin receptor antagonist, the hypotensive effect of aFGF was reduced 38% with 58 microg of antagonist and by 60% with the 420 microg dose (9 +/- 1 vs 22 +/- 3mm Hg, p<0.01). Mean blood pressure decrease was 12 +/- 1 in BNK rats (p<0.01, vs control) and 10 +/- 2 mm Hg in kininogen-depleted ellagic acid-treated rats (p<0.05, vs control). These findings implicate kinins as necessary mediators for the hypotensive effect of aFGF in vivo. A full hypotensive effect of aFGF requires sufficient amounts of kininogens, the precursor molecules of kinins, as well as bradykinin receptors.

Serum levels of basic fibroblast growth factor in acute myocardial infarction

As it has been reported that basic fibroblast growth factor (bFGF) is a circulating peptide and bFGF gene expression is increased after myocardial ischemia, this study was designed to investigate the serum levels of bFGF in patients with acute myocardial infarction (AMI). Using a bFGF enzyme-linked immunoassay, bFGF levels were determined in venous blood of 15 patients with AMI on admission, at 10 days, and 30 days after infarction, and of 15 age-matched healthy volunteers who were used as controls. bFGF serum levels on admission were similar to normal values (7.48 +/- 2.3 vs 8.14 +/- 2.9 pg/ml). However, they significantly increased (16.82 +/- 3.4 pg/ml; p <0.05) 10 days after the onset of AMI, and at 30 days they returned to baseline (7.07 +/- 2.9 pg/ml). The increased bFGF levels at the second week post AMI suggest that bFGF plays an important role in mediating the development of coronary collateral circulation after myocardial ischemia in humans.

Role of fibroblast growth factors in neural trauma

Following a traumatic insult to the adult mammalian central nervous system (CNS), a complex of molecular and cellular responses ensues. Several peptide growth factors seem implicated in the CNS traumatic response. Furthermore, several of them, like some of the members of the fibroblast growth factor family of polypeptides seem to have a protective role. The purpose of this article is to point toward some basic aspects of FGFs neuroprotective activity against traumatic CNS injuries for the development of novel therapeutic strategies in neural trauma.

A partly folded state of acidic fibroblast growth factor at low pH

Acid denaturation of acidic fibroblast growth factor (aFGF) at low ionic strength was monitored by far-ultraviolet circular dichroism and intrinsic fluorescence. The two spectroscopic probes displayed non-coincident transitions, which suggested the accumulation of partly folded species around pH 4.0. Although under these conditions the fluorescence of aFGF resembled that of the unfolded form of the protein, far-ultraviolet circular dichroism and proton nuclear magnetic resonance spectra indicated the presence of persistent secondary and tertiary structure. Moreover, at pH 4.0, aFGF showed cooperative thermal denaturation and interacted weakly with the hydrophobic probe N-phenyl-1-naphthylamine, showing a relatively high level of structure that did not fit into the classical molten globule category. This intermediate is also capable of interacting with liposomes and might represent a membrane translocation-competent form.

Three-dimensional solution structure and stability of phage 434 Cro protein

1H NMR resonances of the phage 434 Cro protein were assigned using standard 2D NMR methods, and its solution structure determined using 867 distance constraints in distance geometry (DIANA) calculations ultimately refined by restrained molecular dynamics (GROMOS). In the 20 best NMR structures, the average pairwise backbone and heavy atom RMSDs are 0.63 +/- 0.14 and 1.53 +/- 0.15 A, respectively, for the structurally well-defined residues 4-65. Residues 1-3 and 66-71 at the N- and C-termini are structurally disordered. The region 4-65 includes five alpha-helices and tight turns which define the hydrophobic core of the protein. The backbone and heavy atom RMSDs for residues 4-65 are 0.92 +/- 0.12 and 1.99 +/- 0.12 A, respectively, for the NMR versus the crystal structures, but there are significant differences in the side-chain conformations and solvent accessibilities for some core residues. Analytical ultracentrifugation experiments confirm that 434 Cro is monomeric even at the high NMR concentrations. 434 Cro folding under NMR solution conditions is two-state as indicated by coincident urea denaturation curves from circular dichroism and intrinsic fluorescence measurements. They yield values for 434 Cro stability which show good correspondence to the free energy for global unfolding determined by NMR hydrogen exchange measurements for the slowest exchanging amide protons.

A non-mitogenic form of acidic fibroblast growth factor reduces neutrophil infiltration in rat ischemic reperfused heart

We studied the effects of a non-mitogenic form of acidic fibroblast growth factor (aFGF) on neutrophil infiltration in a rat model of myocardial ischemia (20 min) and reperfusion (24 hr). Neutrophil infiltration, as assessed by measurement of myeloperoxidase (MPO) activity was compared in homogenates of the infarcted left ventricle and the non-infarcted septum which was used as a reference of normal tissue. Myocardial ischemia followed by reperfusion resulted in severe myocardial injury and high cardiac MPO activity indicative of neutrophil accumulation in the ischemic myocardium. A systemic bolus (i.v.) of aFGF (2.6 microg) administered immediately after myocardial ischemia, significantly reduced (p<0.001) the MPO activity in the ischemic reperfused left ventricle compared to vehicle-treated rats. Furthermore, aFGF significantly attenuated tissue damage and neutrophil accumulation in the area at risk after myocardial ischemia and reperfusion as assessed by conventional histology. The mechanism of this protective effect appears to be related to inhibition of neutrophil extravasation, a critical step in neutrophil-induced myocardial reperfusion injury. Thus, non-mitogenic aFGF appears as an effective cardioprotective treatment for myocardial infarction.

Osteopromotion for cranioplasty: an experimental study in rats using acidic fibroblast growth factor

BACKGROUND

Many growth factors influence the bone healing cascade. Furthermore, the occasional failure of bone repair may in part be due to perturbation in the activation of local growth factors. Local activation of fibroblast growth factors (FGFs) at the fracture site may serve to increase neovascularization, and induce early granulation formation that can affect bone healing.

METHODS

We have performed a rat parietal (6 x 3 mm) critical size defect (CSD). Human recombinant acidic fibroblast growth factor (hraFGF) imbided in agarose was topically administered at the craniectomy site. Control animals received agarose alone in the same manner. Three weeks after surgery, osteopromotion was histologically evaluated.

RESULTS

hraFGF-treated animals show a continuous bridge of regenerated bone extending from one edge of the defect to the other. None of the parietal defects that had been treated with agarose contained new bone in the central portion.

CONCLUSION

Our results suggest an important role of FGFs to promote large cranioplasty repair and support the use of these proteins as an alternative choice for bone grafts and bone substitutes.

Protective effects of acidic fibroblast growth factor against cardiac arrhythmias induced by ischemia and reperfusion in rats

An in vivo study has been conducted to evaluate the effect of acidic fibroblast growth factor (aFGF) on cardiac arrhythmias which occur in transient myocardial ischemia followed by reperfusion. In a rat model of myocardial ischemia and reperfusion, cardiac arrhythmias were assessed during the first three minutes of reperfusion. Systemic administration of 2.6 micrograms aFGF just before coronary recirculation resulted in a significant reduction in incidence and severity of ventricular extra beats (VEBs), ventricular tachycardia (VT) and ventricular fibrillation (VF), compared with control rats (VT incidence: 30% vs 80%, VF incidence: 10% vs 40%; episodes of VT: 4.1 +/- 0.34 vs 8.8 +/- 0.95; episodes of VF: 4.8 +/- 0.32 vs 11.5 +/- 1.47). Our results suggest a novel role for FGFs as potential antiarrhythmic agents.

Protection of rat myocardium by mitogenic and non-mitogenic fibroblast growth factor during post-ischemic reperfusion

The effects of acidic fibroblast growth factor (FGF-1) and basic fibroblast growth factor (FGF-2) and a non mitogenic form of FGF1 on myocardial ischemia and reperfusion were assessed. Rats underwent 10 minutes of coronary artery occlusion followed by 24 hours of reperfusion. Creatinine kinase content of the affected myocardium showed that both fibroblast growth factors 1 and 2 effectively protected against ischemia reperfusion injury (p < 0.01), and that the vasoactive but nonmitogenic form of the FGF1 was equally protective (p < 0.01 versus control + vehicle). The results were confirmed by light and electron-microscopy histological studies. Histological evaluations after treatment with the non-mitogenic fibroblast growth factor 1 showed that it did not generate the severe hyperplasia and connective tissue disorganization observed with the native mitogenic proteins. The possibility of using a non-mitogenic form of fibroblast growth factor for cardio-protection circumvents many of the potentially undesirable effects that may derive from systemically introducing broad spectrum acting fibroblast growth factors in vivo. This myocardial protection observed 24 hours after the treatment with fibroblast growth factors, and the efficacy of the non-mitogenic form of the protein, also suggest that the protective effect of fibroblast growth factors may be due to the increased blood flow rather than to angiogenesis.

Loss of basic fibroblast growth factor in the subcommissural organ of old spontaneously hypertensive rats

The immunocytochemical localization of basic fibroblast growth factor (bFGF) was studied in subcommissural organ (SCO) of aged-matched normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive (SH) rats at 10, 14 and 18 months of age using a polyclonal antibody against bFGF. The bFGF-like immunoreactivity (bFGF-ir) was observed in SCO ependymal cells of young and old normotensive rats. However, a progressive loss of bFGF-immunopositive ependymal SCO cells was observed with age in SH rats (27.24, 57.5 and 96.9% in 10, 14 and 18 months old respectively) compared with aged-matched WKY normotensive rats. Considering the potential role of the SCO in sleep regulation and sodium homeostasis, which are altered in essential hypertension, these data show a new neuroendocrine anomaly to be added to the many others previously observed in this rat strain, when they develop hypertension as they get old.

Sleep promoting effects of intravenously administered acidic fibroblast growth factor

The influence of acidic fibroblast growth factor (aFGF) on sleep was studied in conscious rabbits. An intravenous (i.v.) bolus injection of aFGF induced a significant increase in sleep duration in comparison with animals that received vehicle solution. Somnogenic effects were obtained 30 min following i.v. aFGF administration and lasted about 75 min. Furthermore, the somnogenic effects of aFGF were prevented by pretreatment with the nitric oxide synthase inhibitor L-NAME. Our findings demonstrate a somnogenic effect of aFGF which requires crossing the blood-brain barrier (BBB) and implicate that nitric oxide sleep pathway may be involved in this biological effect.

Fibroblast growth factor decreases locomotor activity in rats

The spontaneous locomotor behavior of rats receiving subcutaneous administration of either acidic or basic fibroblast growth factors was recorded in an activity cage. We report that doses between 1 and 100 micrograms/kg significantly decreased the horizontal and vertical activity, as well as the exploratory and stereotypy behavior of the rats. These effects of fibroblast growth factors seem to be specific since (i) they were cancelled by protein hydrolysis and anti-fibroblast growth factor antibodies, (ii) they were unrelated to their hypotensive activity and (iii) they were not attributable to their high structural similarity with the cytokine interleukin-1. Thus fibroblast growth factors did not show any thermogenic activity, did not affect the hypothalamic output of corticotropin-releasing factor and did not change the plasma levels of corticosterone. Pretreatment of the rats with a specific inhibitor of brain nitric oxide synthase prevented the effects of fibroblast growth factors, suggesting the involvement of nitric oxide in these behavioral modifications. Our results contribute to the accumulating evidence describing non-mitogenic activities of fibroblast growth factors.

Three-dimensional structure of acidic fibroblast growth factor in solution: effects of binding to a heparin functional analog

Acidic and basic fibroblast growth factors (aFGF and bFGF; FGFs) are paradigms of a group of nine closely related proteins known as the fibroblast growth factor family. FGFs induce mitosis in most mesoderm- and neuroectoderm-derived cells, and appear to be involved in diseases caused by anomalous cell proliferation. In vitro assays show that binding to heparin-like glycosaminoglycans is required to elicit the mitogenic activity of these proteins. It has been shown that myo-inositol hexasulfate (MIHS) emulates heparin in the mitogenesis assays of aFGF, and a low-resolution three-dimensional structure in solution of this protein bound to MIHS has been reported. Here we describe the 1H-NMR three-dimensional structure in solution of the free aFGF. Comparison of this structure with that of the protein bound to MIHS, upgraded to a level of refinement equivalent to that of the free protein, shows that MIHS binding causes some slight conformational changes with an increase in the definition of the structure. In addition, amide exchange H/2H rates of the most protected protons, and exchange data of the intermediate and fast-exchanging ones show that the free protein is less stable (< or = 2 kcal/mol) and more flexible in terms of local unfolding equilibria, respectively, than the MIHS-bound one. Thus, MIHS binding to aFGF causes a decrease of its flexibility, which translates into an enhancement of the definition of its three-dimensional structure. The increase of aFGF rigidity affects regions that include those involved in recognizing the cell membrane receptor. Thus, our data suggest that enhancement of structural definition may play a key role in the modulation of the affinity of aFGF by its receptor, and, consequently, of its specific mitogenic activity.

Correction of hypertension by normalization of endothelial levels of fibroblast growth factor and nitric oxide synthase in spontaneously hypertensive rats

Acidic and basic fibroblast growth factors (FGFs) share a wide range of diverse biological activities. To date, low levels of FGF have not been correlated with a pathophysiologic state. We report that blood vessels of spontaneously hypertensive rats are shown to be associated with a marked decrement in endothelial basic FGF content. This decrement correlates both with hypertension and with a decrease in the endothelial content of nitric oxide synthase. Restoration of FGF to physiological levels in the vascular wall, either by systemic administration or by in vivo gene transfer, significantly augmented the number of endothelial cells with positive immunostaining for nitric oxide synthase, corrected hypertension, and ameliorated endothelial-dependent responses to vasoconstrictors. These results suggest an important role for FGFs in blood pressure homeostasis and open new avenues for the understanding of the etiology and treatment of hypertension.

X-ray structure of native full-length human fibroblast-growth factor at 0.25-nm resolution

Acidic fibroblast-growth factor (aFGF) is one of the typical members of a group of nine polypeptides of relatively similar amino acid sequence known as the fibroblast-growth-factor family of proteins. Widely distributed throughout the organism, fibroblast-growth factors seem to be involved in numerous physiological processes ranging from control of cell proliferation and differentiation to modulation of animal behaviour and arterial blood pressure. This wide assortment of biological activities explains their involvement in numerous pathologies. Instability and low yields of the purified protein have precluded high-resolution structural studies of the physiological form of aFGF. Nevertheless, modifications introduced recently into the synthesis and purification procedures of this protein have allowed preparations of samples that, as shown here, are reliable substrates to obtain crystals suitable for X-ray-diffraction studies. These analyses have allowed us to elucidate the three-dimensional structure of the physiological form of human aFGF by molecular-replacement methods, from the previously reported structure of a shortened form of bovine aFGF that was stabilized by point-directed mutagenesis. The structure was refined at a resolution of 0.25 nm to an R factor of 20.4% for 13,109 reflections between 0.6 nm and 0.25 nm, with rmsd of 1.1 pm and 1.9 degrees from ideal bond lengths and bond angles, respectively. Human aFGF folds according to a beta-trefoil topology. This fold consist of six beta-strand pairs. Three of them form a six-stranded beta-barrel structure that is capped at one end by the other three pairs arranged in a triangular array. The N-terminus of aFGF up to residue Pro19 appears flexible in the structure and does not specifically interact with the rest of the molecule.