Isolation of fibroblast growth factor from bovine adrenal gland: physicochemical and biological characterization

Fibroblast growth factor-2 signaling modulates matrix reorganization and cell cycle turnover rate in the regenerating tail of Hemidactylus flaviviridis

Lizards restore their lost tail by the recruitment of multipotent cells which are selectively differentiated into varied cell types so as to sculpt a new tail. The precise coordination of the events involved in this complex process requires crosstalk between many signaling molecules and differential regulation of several mediators that facilitate the achievements of various milestones of regeneration. Fibroblast growth factor-2 is one such signaling molecule which activates a number of intracellular signaling pathways. Herein, the regulatory role of FGF2 during tail regeneration in Hemidactylus flaviviridis was investigated. Upon inhibition of FGFR using SU5402, the FGF2 levels were found to be significantly reduced at both transcript and protein level. Further, the compromised levels of the gelatinases, namely MMP2 and MMP9 in the tail tissues of treated lizards indicate that FGF2 regulates the activity of these enzymes perhaps to facilitate the recruitment of multipotent mesenchymal cells (blastema). The in vivo 5BrdU incorporation assay showed a lower cell proliferation rate in FGF2 signal inhibited animals during all the proliferative stages of regeneration studied. This observation was substantiated by decreased levels of PCNA in treated group. Moreover, from the combined results of Caspase-3 localization and its expression levels in the regenerates of control and SU5402 treated lizards it can be deduced that FGF2 signal regulates apoptosis as well during early stages of regeneration. Overall, the current study indicates beyond doubt that FGF2 signaling plays a pivotal role in orchestrating the matrix reorganization and cell cycle turnover during lizard tail regeneration.

Exercise-induced cognitive plasticity, implications for mild cognitive impairment and Alzheimer's disease

Lifestyle factors such as intellectual stimulation, cognitive and social engagement, nutrition, and various types of exercise appear to reduce the risk for common age-associated disorders such as Alzheimer’s disease (AD) and vascular dementia. In fact, many studies have suggested that promoting physical activity can have a protective effect against cognitive deterioration later in life. Slowing or a deterioration of walking speed is associated with a poor performance in tests assessing psychomotor speed and verbal fluency in elderly individuals. Fitness training influences a wide range of cognitive processes, and the largest positive impact observed is for executive (a.k.a. frontal lobe) functions. Studies show that exercise improves additional cognitive functions such as tasks mediated by the hippocampus, and result in major changes in plasticity in the hippocampus. Interestingly, this exercise-induced plasticity is also pronounced in APOE ε4 carriers who express a risk factor for late-onset AD that may modulate the effect of treatments. Based on AD staging by Braak and Braak (1991) and Braak et al. (1993) we propose that the effects of exercise occur in two temporo-spatial continua of events. The “inward” continuum from isocortex (neocortex) to entorhinal cortex/hippocampus for amyloidosis and a reciprocal “outward” continuum for neurofibrillary alterations. The exercise-induced hypertrophy of the hippocampus at the core of these continua is evaluated in terms of potential for prevention to stave off neuronal degeneration. Exercise-induced production of growth factors such as the brain-derived neurotrophic factor (BDNF) has been shown to enhance neurogenesis and to play a key role in positive cognitive effects. Insulin-like growth factor (IGF-1) may mediate the exercise-induced response to exercise on BDNF, neurogenesis, and cognitive performance. It is also postulated to regulate brain amyloid β (Aβ) levels by increased clearance via the choroid plexus. Growth factors, specifically fibroblast growth factor and IGF-1 receptors and/or their downstream signaling pathways may interact with the Klotho gene which functions as an aging suppressor gene. Neurons may not be the only cells affected by exercise. Glia (astrocytes and microglia), neurovascular units and the Fourth Element may also be affected in a differential fashion by the AD process. Analyses of these factors, as suggested by the multi-dimensional matrix approach, are needed to improve our understanding of this complex multi-factorial process, which is increasingly relevant to conquering the escalating and intersecting world-wide epidemics of dementia, diabetes, and sarcopenia that threaten the global healthcare system. Physical activity and interventions aimed at enhancing and/or mimicking the effects of exercise are likely to play a significant role in mitigating these epidemics, together with the embryonic efforts to develop cognitive rehabilitation for neurodegenerative disorders.

Inhibition of LH-stimulated androgen production in rat immature Leydig cells: Effects on nuclear receptor steroidogenic factor 1 by FGF2

Both fibroblast growth factor 2 (FGF2) and luteinizing hormone (LH) have been reported to regulate androgen production in Leydig cells in progenitor Leydig cells. The objective of the present study is to examine the regulation of androgen production in rat immature Leydig cells (ILCs). ILCs were isolated from 35-day-old rat testes and cultured in DMEM/F12 medium with LH (1 ng/ml) or FGF2 (10 ng/ml). 5alpha-Androstane-3alpha, 17beta-diol (3alpha-DIOL), the primary androgen in ILCs, and testosterone (T) were measured by Radioimmuno assay. The results showed the LH stimulated androgen production in ILCs, and FGF2 did not. However, FGF2 decreased the LH-stimulated androgen production. Real-time PCR and enzyme assay showed that FGF2 decreased levels of several steroidogenic enzymes, inhibited the expressions of steroidogenic acute regulatory (StAR) protein and steroidogenic factor 1 (Nr5a1) in LH-stimulated ILCs. FGF2-mediated inhibition of Nr5a1gene expression may be the mechanism through which FGF2 inhibits LH-stimulated androgen production.

A turn-like structure "KKPE" segment mediates the specific binding of viral protein A27 to heparin and heparan sulfate on cell surfaces

Vaccinia viral envelope protein A27 (110 amino acids) specifically interacts with heparin (HP) or heparan sulfate (HS) proteoglycans for cell surface attachment. To examine the binding mechanism, a truncated soluble form of A27 (sA27-aa; residues 21-84 of A27) with Cys(71) and Cys(72) mutated to Ala was used as the parent molecule. sA27-aa consists of two structurally distinct domains, a flexible Arg/Lys-rich heparin-binding site (HBS) (residues 21-32; (21)STKAAKKPEAKR(32)) and a rigid coiled-coil domain (residues 43-84), both essential for the specific binding. As shown by surface plasmon resonance (SPR), the binding affinity of sA27-aa for HP (K(A) = 1.25 x 10(8) m(-1)) was approximately 3 orders of magnitude stronger than that for nonspecific binding, such as to chondroitin sulfate (K(A) = 1.65 x 10(5) m(-1)). Using site-directed mutagenesis of HBS and solution NMR, we identified a "KKPE" segment with a turn-like conformation that mediates specific HP binding. In addition, a double mutant T22K/A25K in which the KKPE segment remained intact showed an extremely high affinity for HP (K(A) = 1.9 x 10(11) m(-1)). Importantly, T22K/A25K retained the binding specificity for HP and HS but not chondroitin sulfate, as shown by in vitro SPR and in vivo cell adhesion and competitive binding assays. Molecular modeling of the HBS was performed by dynamics simulations and provides an explanation of the specific binding mechanism in good agreement with the site-directed mutagenesis and SPR results. We conclude that a turn-like structure introduced by the KKPE segment in vaccinia viral envelope protein A27 is responsible for its specific binding to HP and to HS on cell surfaces.

Basic fibroblast growth factor, neurofilament, and glial fibrillary acidic protein immunoreactivities in the myenteric plexus of the rat esophagus and colon

The enteric nervous system consists of a number of interconnected networks of neuronal cell bodies and fibers as well as satellite cells, the enteric glia. Basic fibroblast growth factor (bFGF) is a mitogen for a variety of mesodermal and neuroectodermal-derived cells and its presence has been described in many tissues. The present work employs immunohistochemistry to analyze neurons and glial cells in the esophageal and colic enteric plexus of the Wistar rat for neurofilament (NF) and glial fibrillary acidic proteins (GFAP) immunoreactivity as well as bFGF immunoreactivity in these cells. Rats were processed for immunohistochemistry; the distal esophagus and colon were opened and their myenteric plexuses were processed as whole-mount preparations. The membranes were immunostained for visualization of NF, GFAP, and bFGF. NF immunoreactivity was seen in neuronal cell bodies of esophageal and colic enteric ganglia. GFAP-immunoreactive enteric glial cells and processes were present in the esophageal and colic enteric plexuses surrounding neuronal cell bodies and axons. A dense net of GFAP-immunoreactive processes was seen in the ganglia and connecting strands of the myenteric plexus. bFGF immunoreactivity was observed in the cytoplasm of the majority of the neurons in the enteric ganglia of esophagus and colon. The two-color immunoperoxidase and immunofluorescence methods revealed bFGF immunoreactivity also in the nucleus of GFAP-positive enteric glial cells. The results suggest that immunohistochemical localization of NF and GFAP may be an important tool in the study of the plasticity in the enteric nervous system. The presence of bFGF in neurons and glia of the myenteric plexus of the esophagus and the colon indicates that this neurotrophic factor may exert autocrine and paracrine actions in the enteric nervous system.

Increased fibroblast growth factor-like autoantibodies in serum from a subset of patients with cancer-associated hypercalcemia

Basic fibroblast growth factor (bFGF) is a potent tumor angiogenesis factor which lacks an amino-terminal signal sequence and does not normally circulate in serum from normal subjects. Naturally-occurring autoantibodies which mimicked basic fibroblast growth factor were described in serum from patients with multiple endocrine neoplasia type 1 prolactinoma or sporadic growth-hormone-secreting adenoma associated with increased bFGF. Since bFGF was increased in serum from a variety of cancers, we used endothelial cell proliferation assay(s) to test for bioactivity in the IgG fraction of serum from 56 patients with cancer-associated hypercalcemia, and normal or control subjects. We now report increased IgG-like endothelial cell activity in serum from a hyper prolactinemic subset (4/19 breast cancer; 1/14 renal cancer; 0/23 lung cancer) of cancer-associated hypercalcemic subjects. Highest activity was found in serum from three breast cancer patients who suffered spinal cord compression/metastases. The activity had properties of antiidiotype bFGF antibodies including reaction with anti-human IgG antibodies, and complete neutralization by rabbit antibodies to intact bFGF. The activity in endothelial cells persisted after storage at 0-4 C for 5 yrs; and [prepared by SDS-PAGE and immunoblotting with anti-human IgG] had apparent mol wt corresponding to the heavy chains of IgG. Serum IgG-like activity from 5 of 5 breast cancer patients and 2 of 2 prostate cancer subjects tested [prepared by anti-bFGF antibody, protein-A immunoaffinity, and hydroxyapatite (HA) chromatography] yielded peak HA-adsorbed activity that eluted with 0.4 M sodium phosphate, and was neutralized 70% by antibodies to intact bFGF. Cancer sera mean peak specific activity (12.0 ng-eq bFGF/ug protein) (n = 7) significantly exceeded (P < 0.001) normal sera mean peak specific activity (0.46 ng-eq bFGF/ug protein) (n = 6) in the 0.4 M sodium phosphate eluate fraction from hydroxyapatite columns. These results imply that long-lasting, bioactive FGF-like autoantibodies may arise spontaneously (and contribute to pathophysiology) in subsets of cancer patients with osseous metastases.

Failure of airway healing in an ovine autotransplantation model that includes basic fibroblast growth factor

OBJECTIVE

Basic fibroblast growth factor is among the most potent promoters of angiogenesis. Its ability to enhance the blood supply to ischemic airways or nonvascularized tracheal autograft has been demonstrated. Its cumulative effect with muscular wrapping and its efficacy in a noncanine large animal model remain unknown. Treatment with basic fibroblast growth factor and muscular wrapping were compared with no special treatment and with muscular wrapping alone in an ovine tracheal autotransplantation model.

METHODS

All sheep underwent orthotopic tracheal transplantation with 5 to 8 ring autografts in the cervical trachea. Fifteen sheep were classified randomly into the following three groups: no treatment (group A, n = 5), muscular wrapping with the right sternomastoid muscle (group B, n = 5), and topical administration of fibrin glue enriched with 2 microg/cm(2) basic fibroblast growth factor (group C, n = 5).

RESULTS

Devascularized tracheal autografts were unable to maintain their structural integrity without other treatment (group A). However, the grafts were surrounded by well-vascularized connective tissue. In the muscular wrapping group (group B), infections occurred around the grafts, and the muscular wrapping was subject to necrosis. No neovascularization of the grafts occurred. Therapy with basic fibroblast growth factor (group C) led to improved muscular wrapping circulation and to adherence to the tracheal stumps. However, no success was achieved in validating the circulation in the grafts.

CONCLUSIONS

In contrast to the results achieved by other authors with canine models, the neovascularization of tracheal autografts was not achieved in sheep with the topical administration of basic fibroblast growth factor. Cranially pediculated muscular wrapping led to poorer circulation in the tissue around the graft than did no therapy at all.

Maintenance of Intermediolateral Spinal Cord Neurons by Fibroblast Growth Factor Administered to the Medullectomized Rat Adrenal Gland: Dependence on Intact Adrenal Innervation and Cellular Organization of Implants

We have previously shown that basic fibroblast growth factor (bFGF; 2 microg), when administered in gelfoams implanted to medullectomized adult rat adrenal glands, maintains target-deprived preganglionic neurons located in the intermediolateral column (IML) of the spinal cord. We show now that administration of 600 or 60 ng/implant/organ of the biologically active recombinant protein also maintains IML-neurons. The effects depend on an intact organ nerve supply since administration of bFGF-implants to the medullectomized and denervated (splanchnicotomized) organ abolishes the maintenance effects for IML-neurons. A possible regeneration of cholinergic nerve fibres was assessed by quantitative determination of choline acetyltransferase (ChAT)-activity and ultrastructurally under various treatments. When compared to a cytochrome-(Cyto)-C treatment, bFGF significantly increased ChAT-activity in the innervated adrenal gland after 4 weeks, suggesting that sprouting of cholinergic nerve fibres and/or recovery of enzyme activity had occurred. Electron microscopically, unmyelinated axons associated with Schwann cells were only found in bFGF, but not in Cyto-C-implants. We conclude that exogenous bFGF or a yet unidentified trophic molecule possibly induced by bFGF in the adrenal gland acts as a retrogradely transported messenger serving for the maintenance of spinal cord IML-neurons in vivo. By stimulating axonal sprouting, bFGF might facilitate access of trophic material to nerve fibres.

Effect of intravenous bisphosphonates on release of basic fibroblast growth factor in serum of patients with cancer-associated hypercalcemia

Basic fibroblast growth factor (bFGF) is a potent tumor angiogenesis factor and normal constituent of bone extracellular matrix which does not normally circulate in serum of nonpregnant adult humans. We examined the effects of acute administration of intravenous bisphosphonates on release of bFGF in human serum. Twenty seven men and women (mean age, 64 yr) with cancer-associated hypercalcemia, the majority of whom had osseous metastases, were treated once with an intravenous bisphosphonate. Nearly all twelve patients with elevated baseline serum bFGF ranging from 5-27 pg/mL showed significant decreases in serum bFGF (2-7 days) after iv bisphosphonate treatment. The mathematical product of the patients' initial serum bFGF and intial serum calcium concentration, the 'Ca x bFGF product', was significantly negatively (r = -0.91, P < 0.001) correlated with the acute change in serum bFGF level. No consistent relationship was observed between serum bFGF and serum parathyroid hormone related peptide (PTHrP) levels in the hypercalcemic cancer patients. In a subset of patients with non-hematological malignancies and low baseline serum bFGF, acute changes in serum bFGF were significantly negatively (r = -0.66, P < 0.01) correlated with acute change in serum calcium concentration. These results indicate that release of bFGF in serum of patients with cancer-associated hypercalcemia likely depends predominantly on increased bone resorption. Acute change in low serum levels of bFGF in patients with cancer-associated hypercalcemia treated with intravenous bisphosphonates may be physiologically inversely regulated by acute change in the serum calcium concentration.

Differential regulation of the fibroblast growth factor (FGF) family by alpha(2)-macroglobulin: evidence for selective modulation of FGF-2-induced angiogenesis

The fibroblast growth factor (FGF) family has an important role in processes such as angiogenesis, wound healing, and development in which precise control of proteinase activity is important. The human plasma proteinase inhibitor alpha(2)-macroglobulin (alpha(2)M) regulates cellular growth by binding and modulating the activity of many cytokines and growth factors. These studies investigate the ability of native and activated alpha(2)M (alpha(2)M*) to bind to members of the FGF family. Both alpha(2)M and alpha(2)M* bind specifically and saturably to FGF-1, -2, -4, and -6, although the binding to alpha(2)M* is of significantly higher affinity. Neither alpha(2)M nor alpha(2)M* bind to FGF-5, -7, -9, or -10. FGF-2 was chosen for more extensive study in view of its important role in angiogenesis. It was demonstrated that FGF-2 binds to the previously identified TGF-beta binding site. The alpha(2)M* inhibits FGF-2-dependent fetal bovine heart endothelial cell proliferation in a dose-dependent manner. Unexpectedly, alpha(2)M* does not affect FGF-2-induced vascular tubule formation on Matrigel basement membrane matrix or collagen gels. Further studies demonstrate that FGF-2 partitions between fluid-phase alpha(2)M* and solid-phase Matrigel or collagen. These studies suggest that the ability of alpha(2)M* to modulate the activity of FGF-2 is dependent on an interplay with extracellular matrix components. (Blood. 2001;97:3450-3457)

Fibroblast growth factor-2 inhibits the maturation of pro-insulin-like growth factor-II (Pro-IGF-II) and the expression of insulin-like growth factor binding protein-2 (IGFBP-2) in the human adrenocortical tumor cell line NCI-H295R

The IGF system is thought to play a major role in adrenocortical tumorigenesis. In this study, we used the NCI H295R cell line as a model to investigate the effects of fibroblast growth factor-2 (FGF-2), a potent mitogen for normal adrenal cells, on the proliferation and on the expression of the IGF system in cultured adrenocortical tumor cells. Three immunoreactive FGF-2 isoforms of molecular masses 18, 22, and 24 kDa were detected in H295R cell extracts. Recombinant human FGF-2 stimulated the proliferation of adrenocortical tumor cells in a dose- and time-dependent manner, with a maximal effect at a concentration of about 1 ng/ml. Treatment of H295R cells with 10 ng/ml FGF-2 for 7 days had no significant effect on IGF-II messenger RNA levels. However, a marked increase in levels of intracellular IGF-II protein was detected by immunoblotting. In contrast, FGF-2 induced a marked decrease in the amount of IGF-II protein secreted, with the disappearance of mature IGF-II and secretion of higher molecular forms of the growth factor, suggesting modifications of IGF-II processing. Cell cultures in the presence of brefeldin A (1 microg/ml), a specific inhibitor of protein secretion, suggested that FGF-2 did not increase IGF-II synthesis but instead inhibited the secretion of pro-IGF-II from H295R cells, thereby impairing the final steps of IGF-II processing to the mature 7.5-kDa peptide. At the same concentrations, FGF-2 also decreased both IGFBP-2 messenger RNA and secreted protein, which might increase IGF-II bioavailability. No proteolysis of IGFBP-2 was detected in FGF-2-conditioned medium. Altogether, these results indicate that FGF-2 is mitogenic for NCI H295R tumor cells and regulates the expression of both IGF-II and IGFBP-2 in this tumor model. Moreover, this study shows a novel effect of FGF-2, by which this growth factor modulates the processing of pro-IGF-II.

Transplantation of primary bovine adrenocortical cells into scid mice

Bovine adrenocortical cells were transplanted into scid mice, using a small cylinder inserted beneath the kidney capsule. The tissue formed from primary bovine adrenocortical cells replaced the essential functions of the animals' own adrenal glands, which were removed during the cell transplantation procedure. Most adrenalectomized animals bearing transplanted cells survived indefinitely, whereas adrenalectomized control animals died following surgery. Formation of well-vascularized tissue at the site of transplantation was associated with stable levels of cortisol in the blood, replacing the mouse glucocorticoid (corticosterone). Ultrastructurally, the cultured cells before transplantation had characteristics of rapidly growing cells, but tissue formed in vivo showed features associated with active steroidogenesis. We investigated two potentially critical aspects of the procedure: the provision of support for angiogenesis in the transplant by the inclusion of FGF-secreting 3T3 cells with the adrenocortical cells; and the administration of synthetic steroids as a temporary replacement for steroids lost by adrenalectomy. We found that FGF was required for the rapid formation of well-vascularized tissue, whereas steroid administration avoided some early mortality but was not absolutely required. In contrast to transplants formed from clonal cells, which did not usually secrete aldosterone, transplants formed from primary bovine adrenocortical cells, even though derived from the zona fasciculata, secreted aldosterone as well as cortisol.

Heparin-binding angiogenic factors (basic fibroblast growth factor and vascular endothelial growth factor) in early neonatal life

This study investigated whether serum levels of the potent angiogenic factors basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF), which are abundantly produced in utero by the placenta and fetal tissues, change after birth at term, consequent to diminished angiogenic but increased adaptational demands in extrauterine life. Moreover, whether serum levels of the above factors correlate with sex, birth weight, or mode of delivery was also evaluated. One milliliter of blood was drawn from 30 healthy, appropriate for gestational age, full-term infants on d 1 (N1) and 4 (N4) postnatally. In 10 of the above cases maternal and umbilical cord blood samples were also drawn. Serum was analyzed by enzyme immunoassays, using commercial kits. Levels of bFGF and VEGF were significantly lower in maternal serum than in umbilical cord (p = 0.02 and 0.036, respectively) or N1 (p = 0.009 and 0.006, respectively) and N4 serum (p = 0.009 and 0.006, respectively). Levels of bFGF in umbilical cord serum did not differ significantly from those in N1 and N4. In contrast, levels of VEGF rose in N1, differing significantly from levels in umbilical cord serum (p = 0.008). Both factors did not change from N1 to N4. Neither bFGF nor VEGF serum levels depended on sex, mode of delivery, or birth weight. In conclusion, bFGF levels in neonates do not differ from levels in fetuses, possibly reflecting diminished angiogenesis in extrauterine life, which already has started in utero. On the contrary, neonatal levels of VEGF rise significantly after birth, possibly signifying adaptation demands, in addition to angiogenesis, as VEGF is also considered a regulator of normal function.

Regulation of the hypothalamic-pituitary-adrenal axis by cytokines: actions and mechanisms of action

Glucocorticoids are hormone products of the adrenal gland, which have long been recognized to have a profound impact on immunologic processes. The communication between immune and neuroendocrine systems is, however, bidirectional. The endocrine and immune systems share a common "chemical language," with both systems possessing ligands and receptors of "classical" hormones and immunoregulatory mediators. Studies in the early to mid 1980s demonstrated that monocyte-derived or recombinant interleukin-1 (IL-1) causes secretion of hormones of the hypothalamic-pituitary-adrenal (HPA) axis, establishing that immunoregulators, known as cytokines, play a pivotal role in this bidirectional communication between the immune and neuroendocrine systems. The subsequent 10-15 years have witnessed demonstrations that numerous members of several cytokine families increase the secretory activity of the HPA axis. Because this neuroendocrine action of cytokines is mediated primarily at the level of the central nervous system, studies investigating the mechanisms of HPA activation produced by cytokines take on a more broad significance, with findings relevant to the more fundamental question of how cytokines signal the brain. This article reviews published findings that have documented which cytokines have been shown to influence hormone secretion from the HPA axis, determined under what physiological/pathophysiological circumstances endogenous cytokines regulate HPA axis activity, established the possible sites of cytokine action on HPA axis hormone secretion, and identified the potential neuroanatomic and pharmacological mechanisms by which cytokines signal the neuroendocrine hypothalamus.

RNA and protein interactions modulated by protein arginine methylation

This review summarizes the current status of protein arginine N-methylation reactions. These covalent modifications of proteins are now recognized in a number of eukaryotic proteins and their functional significance is beginning to be understood. Genes that encode those methyltransferases specific for catalyzing the formation of asymmetric dimethylarginine have been identified. The enzyme modifies a number of generally nuclear or nucleolar proteins that interact with nucleic acids, particularly RNA. Postulated roles for these reactions include signal transduction, nuclear transport, or a direct modulation of nucleic acid interactions. A second methyltransferase activity that symmetrically dimethylates an arginine residue in myelin basic protein, a major component of the axon sheath, has also been characterized. However, a gene encoding this activity has not been identified to date and the cellular function for this methylation reaction has not been clearly established. From the analysis of the sequences surrounding known arginine methylation sites, we have determined consensus methyl-accepting sequences that may be useful in identifying novel substrates for these enzymes and may shed further light on their physiological role.

Improved airway healing using basic fibroblast growth factor in a canine tracheal autotransplantation model

OBJECTIVE

We studied 22 dogs to examine the effect of basic fibroblast growth factor (bFGF) alone, in comparison with omental or muscular wrapping on airway healing in a tracheal autotransplantation model.

SUMMARY BACKGROUND DATA

Basic fibroblast growth factor is one of the most potent promoters of angiogenesis and has an ability to enhance blood supply to the ischemic airway. Topical administration of a fibrin glue enriched with 5 microg/cm2 bFGF, determined as a proportion of surface area of the tracheal grafts, improved revascularization of orthotopic canine tracheal autografts in a previous study.

METHODS

All animals received orthotopic tracheal transplantation using 6-ring autografts that occupied a distal part of the thoracic trachea. Twenty-two animals were classified randomly into the following four groups: no treatment (Group G1, n = 4), muscular wrapping (Group G2, n = 4), omental wrapping (Group G3, n = 4), and topical administration of fibrin glue enriched with 5 microg/cm2 bFGF (Group G4, n = 10). Autografts were harvested 60 days after transplantation and assessed by the percent patency and histology.

RESULTS

Devascularized tracheal autografts could not maintain their structural integrity without other treatments (Group G1). In contrast, more than half of all autografts receiving treatments remained viable, as demonstrated by gross and histologic findings (Groups G2, G3, and G4). Treatments with bFGF and omentum showed significantly better graft viability than no treatment. However, there was no statistical difference in the viability of tracheal autografts among the three treatment groups. In terms of the time performance ratio, bFGF was the best treatment for the devascularized autografts.

CONCLUSIONS

Topical administration of bFGF was superior to the omental or muscular wrapping in terms of the time performance ratio. Clinical trials will be necessary to determine whether these findings are applicable to humans.

Increased bFGF level in the serum of patients with phenytoin-induced gingival overgrowth

To elucidate the involvement of bFGF (basic fibroblast growth factor) in the pathogenesis of phenytoin-induced gingival overgrowth, we measured the concentration of bFGF in the serum of 36 epileptic patients taking phenytoin and in 94 normal volunteers by enzyme-linked immunosorbent assay technique. The concentration of phenytoin in serum was determined by high-performance liquid chromatography. In 34 of 36 patients taking phenytoin in this investigation, apparent gingival overgrowth was noticed. The mean concentration of bFGF was 33.9+/-18.5 pg/ml in the overgrowth group and 10.6+/-5.2 pg/ml in the volunteer group (p<0.01). The serum phenytoin level did not correlate (r=0.22, p=0.2) with the degree of gingival overgrowth but there was a significant correlation (r=0.38, p=0.023) between the degree of gingival overgrowth and the serum bFGF level. However, no correlation was observed among age, daily phenytoin dose, total phenytoin dose, duration of phenytoin therapy, serum phenytoin level, or serum bFGF level. The results suggested that enhanced serum bFGF level was implicated in the pathogenesis of phenytoin-induced gingival overgrowth.

Developmental and functional biology of the primate fetal adrenal cortex

The unique characteristics of the primate (particularly human) fetal adrenal were first realized in the early 1900s when its morphology was examined in detail and compared with that of other species. The unusual architecture of the human fetal adrenal cortex, with its unique and disproportionately enlarged fetal zone, its compact definitive zone, and its dramatic remodeling soon after birth captured the interest of developmental anatomists. Many detailed anatomical studies describing the morphology of the developing human fetal adrenal were reported between 1920 and 1960, and these morphological descriptions have not changed significantly. More recently, it has become clear that fetal adrenal cortical growth involves cellular hypertrophy, hyperplasia, apoptosis, and migration and is best described by the migration theory, i.e. cells proliferate in the periphery, migrate centripetally, differentiate during their migration to form the functional cortical zones, and then likely undergo apoptosis in the center of the cortex. Consistent with this model, cells of intermediate phenotype, arranged in columnar cords typical of migration, have been identified between the definitive and fetal zones. This cortical area has been referred to as the transitional zone and, based on the expression of steroidogenic enzymes, we consider it to be a functionally distinct cortical zone. Elegant experiments during the 1950s and 1960s demonstrated the central role of the primate fetal adrenal cortex in establishing the estrogenic milieu of pregnancy. Those findings were among the first indications of the function and physiological role of the human fetal adrenal cortex and led Diczfalusy and co-workers to propose the concept of the feto-placental unit, in which DHEA-S produced by the fetal adrenal cortex is used by the placenta for estrogen synthesis. Tissue and cell culture techniques, together with improved steroid assays, revealed that the fetal zone is the primary source of DHEA-S, and that its steroidogenic activity is regulated by ACTH. In recent years, function of the human and rhesus monkey fetal adrenal cortical zones has been reexamined by assessing the localization and ontogeny of steroidogenic enzyme expression. The primate fetal adrenal cortex is composed of three functionally distinct zones: 1) the fetal zone, which throughout gestation does not express 3 beta HSD but does express P450scc and P450c17 required for DHEA-S synthesis; 2) the transitional zone, which early in gestation is functionally identical to the fetal zone but late in gestation (after 25-30 weeks) expresses 3 beta HSD, P450scc, and P450c17, and therefore is the likely site of glucocorticoid synthesis, and 3) the definitive zone, which lacks P450c17 throughout gestation but late in gestation (after 22-24 weeks) expresses 3 beta HSD and P450scc, and therefore is the likely site of mineralocorticoid synthesis. Indirect evidence, based on effects of P450c21 deficiency and maternal estriol concentrations, indicate that the fetal adrenal cortex produces cortisol and DHEA-S early in gestation (6-12 weeks). However, controversy exists as to whether cortisol is produced de novo or derived from the metabolism of progesterone, as data regarding the expression of 3 beta HSD in the fetal adrenal cortex early in gestation are conflicting. During the 1960s, Liggins and colleagues demonstrated that in the sheep, cortisol secreted by the fetal adrenal cortex late in gestation regulates maturation of the fetus and initiates the cascade of events leading to parturition. Those pioneering discoveries provided insight into the mechanism underlying the timing of parturition and therefore were of particular interest to obstetricians and perinatologists confronted with the problems of preterm labor. However, although cortisol emanating from the fetal adrenal cortex promotes fetal maturation in primates as it does in sheep, its role in the regulation of primate parturition, unlike that in sheep

Peptide growth factors and the adrenal cortex

Increasing evidence suggests that the actions of classical stimulants of adrenocortical growth and function, such as ACTH or dietary sodium restriction, may partially be mediated via locally produced regulators. Several peptide growth factors, such as basic fibroblast growth factor, insulin-like growth factors, and transforming growth factor-beta 1, have emerged in recent years as multifunctional molecules that typically play such regulatory roles. Adrenocortical cells are highly responsive to these growth factors, in particular in the regulation of cell growth and differentiated functions, such as steroidogenesis. In addition, growth factor expression in the adrenal cortex has been shown to be regulated by physiological stimulants. The spatial expression, release, and activation of these growth factors may, therefore, locally mediate or amplify the actions of the hypothalamo-pituitary axis and the renin-angiotensin system on adrenocortical proliferation, differentiation, and steroidogenesis.

Role of growth factors in the developmental regulation of the human fetal adrenal cortex

Development of the human fetal adrenals is characterized by rapid growth and high levels of steroidogenic activity during the latter two-thirds of pregnancy. By midgestation, the human fetal adrenals are composed of two distinct cortical zones: the predominant fetal zone, which occupies 80-90% of the cortical volume and produces large amounts of the delta 5-steroid dehydroepiandrosterone sulfate, and the narrow definitive zone, which surrounds the fetal zone. Late in gestation, the peripheral portion of the fetal zone develops into a third, functionally distinct compartment, the transitional zone, which is the likely site of cortisol synthesis. Soon after birth, the adrenal cortex is remodeled and the fetal zone disappears. The adult cortical zones are thought to arise from the definitive zone, which persists postnatally. Development of the human fetal adrenals is regulated primarily by corticortropin (ACTH) secreted from the fetal pituitary. However, as ACTH is not a mitogen per se, its proliferative actions on human fetal adrenal cortical cells are thought to be mediated by autocrine/paracrine growth factors produced by adrenal cortical cells in response to ACTH. In addition, these growth factors appear to modulate the functional response of fetal adrenal cortical cells to ACTH. The roles of several growth factors, including the insulin like growth factors I and II (IGF-I and IGF-II), epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), activin, inhibin, and the transforming growth factors alpha and beta (TGF-alpha and TGF-beta) have been examined. In cultured human fetal adrenal cortical cells, EGF, bFGF, and IGF-I and -II are mitogenic, whereas activin and TGF-beta inhibit proliferation. IGF-II, activin, and TGF-beta also modulate ACTH-stimulated steroidogenesis. Human fetal adrenal cortical cells express IGF-II, bFGF and the activin/inhibin subunits, and the abundance of mRNAs for each of these factors is up-regulated by ACTH, suggesting that these growth factors are autocrine/paracrine mediators of ACTH action. Thus, although human adrenal development is primarily regulated by ACTH, its actions appear to be mediated/modulated by a cohort of locally expressed growth factors, the net effect of which results in the unique growth and steroidogenic activity of the human fetal adrenal cortex.

TGF-beta rescues target-deprived preganglionic sympathetic neurons in the spinal cord

Transforming growth factors beta (TGF-beta), a family of pleiotropic cytokines, are widely distributed in the developing and adult nervous system. In order to further determine the neural functions of TGF-beta, we have localized the TGF-beta isoforms 1, 2 and 3 in the adult rat adrenal medulla and studied the neuroprotective capacity of one representative family member, TGF-beta 2, for those spinal cord neurons which innervate adrenal chromaffin cells and which die after destruction of the adrenal medulla. Unilateral electrothermal destruction of the adrenal medulla led to the disappearance of 25% of sympathetic preganglionic neurons, which are located in the intermediolateral (IML) column of thoracic spinal cord segments 7-10 and can be selectively marked by NADPH-diaphorase. The neurons which disappeared following adrenomedullectomy constitute the full set of neurons that innervate the adrenal medulla. Implantation of gelfoam soaked with 0.5 micrograms TGF-beta 2 into the adrenal wound cavity rescued all spinal cord neurons in the IML ipsilaterally to the lesioned side. Cytochrome c was not effective. Injections of [125I]TGF-beta 2 into the adrenal medulla did not result in retrograde transport and subsequent labelling of spinal cord neurons, suggesting that TGF-beta may exert its neuroprotective actions by indirect mechanisms. TGF-beta applied to cultured adrenocortical cells did not overtly increase the amount of mRNA for fibroblast growth factor-2, an established trophic molecule for sympathetic preganglionic spinal cord neurons. The mechanisms by which TGF-beta exerts its neurotrophic effect are therefore unclear. Even so, our data provide the first evidence that TGF-beta may play an important role in vivo in the control of maintenance of a population of spinal cord neurons.

Co-existence of NADPH-diaphorase, fibroblast growth factor-2 and fibroblast growth factor receptor in spinal autonomic system suggests target-specific actions

In the rat spinal cord, we found substantial co-existence of fibroblast growth factor-2, fibroblast growth factor receptor (type-1 or flg) immunoreactivity and reduced nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase activity (a histochemical marker for neuronal nitric oxide synthase) in preganglionic autonomic cell groups of intermediate layers VI, VII and X. Anti-fibroblast growth factor-2 and anti-nitric oxide synthase binding sites were confined to the cytoplasm of reactive neurons as judged by immunogold electron microscopy. Within the major autonomic nucleus, i.e. intermediolateral column, three different populations were identified: (i) fibroblast growth factor and fibroblast growth factor receptor, (ii) fibroblast growth factor/NADPH-diaphorase and (iii) NADPH-diaphorase-only stained cell groups. Sympathoadrenal neurons were prelabelled with fluorescent tracer Fast Blue and co-stained for fibroblast growth factor-like protein and NADPH-diaphorase, suggesting heterologous diversification of neuronal phenotypes and functional organization in the spinal autonomic system. Our findings suggest intriguing roles for nitric oxide and fibroblast growth factor-2 cytokine in the preganglionic sympathetic spinal cord system: The "short-term" diffusible messenger nitric oxide may act as "tonic" and/or "phasic" signal within rostrocaudally oriented function-specific preganglionic units necessary for integrated target control. The "long-term" messenger fibroblast growth factor-2 may be involved in, for example, cytokine-dependent regulation of neuronal NADPH-diaphorase/nitric oxide synthase. Furthermore, co-existence of NADPH-diaphorase, fibroblast growth factor-2 and receptor in sympathoadrenal neurons suggest mutual target-specific regulatory functions, e.g. hormone release and blood perfusion or maintenance of phenotype and plasticity responsiveness of adrenal medullary tissue.

Quantification of myotrophin from spontaneously hypertensive and normal rat hearts

A novel peptide, myotrophin, has been isolated, purified, cloned, and sequenced from the hearts of spontaneously hypertensive rats (SHR) and from dilated cardiomyopathic human heart tissue. Myotrophin accelerates myocyte growth by stimulating protein synthesis (not by altering myocardial cell division). Our successive studies were conducted to evaluate the pathophysiological significance of myotrophin; a solid-phase radioimmunoassay technique was developed for quantifying the protein in hypertrophied and normal hearts. Specific antipeptide antibody was raised in rabbits against a peptide that represents a selected amino acid sequence of a 17-amino acid myotrophin segment by using the multiple antigenic peptide technique. The specificity of the antibody was evaluated by determining the affinity constant after constructing the Scatchard plot obtained from the ratio of bound to free myotrophin against bound myotrophin. The value obtained was 2.61 x 10(7) L/mol. The specificity was further demonstrated by Western blot analysis, in which a single protein band was obtained in the region of 12 kD. Pretreatment of the antibody with myotrophin completely blocked the binding sites, because no protein band was detected on the immunoblot. The antibody prevented the myocardial protein synthesis induced by myotrophin as revealed by the blockage of the stimulation of [3H]leucine incorporation into myocyte protein. Quantification of myotrophin from different heart tissues was achieved by Western blot and dot blot analyses. Amounts of myotrophin present in different dots were determined by using a video image analyzer. The level of myotrophin in the embryonic tissue was found to be similar in male normal and SHR hearts.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence for fibroblast growth factor mediation of compensatory adrenocortical proliferation

The role of basic fibroblast growth factor (bFGF) in the neurally mediated control of compensatory adrenocortical cell proliferation which occurs in response to unilateral adrenalectomy has been investigated. Three isoforms of bFGF have been identified in the rat adrenal with Western blots and bFGF immunoreactivity is most concentrated in the glomerulosa cells. A high affinity binding site (Kd = 10 pM) was identified in primary cultures of rat glomerulosa cells. Using autoradiography of 125I-bFGF binding, in vivo bFGF binding sites were found concentrated in the glomerulosa as well as the capsule cells. The compensatory adrenocortical proliferation was blocked by suramin and bFGF receptor density appeared to be regulated during this proliferation. These results support a role for bFGF in autocrine and paracrine stimulation of proliferation in the adrenal cortex and capsule. To specifically block the receptor-mediated effect of bFGF in this response, we have developed an antisense strategy. Antisense oligodeoxynucleotide targeted against bFGF-receptor mRNA blocks the proliferative effect of bFGF in primary glomerulosa cell cultures by approximately 50%. These results indicate that this antisense strategy interferes with the expression of bFGF-receptors and is an effective technique to reduce the proliferative effect of bFGF via the effect on its receptor.

Basic fibroblast growth factor-induced increase in 125I-human chorionic gonadotropin binding to luteinizing hormone receptors in cultured immature Leydig cells is mediated by binding to heparan sulfate proteoglycans

Previous studies have shown that basic fibroblast growth (bFGF) has a biphasic effect on 125I-hCG binding to LH receptors in cultured Leydig cells from immature rats. Low concentrations of bFGF (0.1-1.0 ng/ml) progressively decreased binding, while higher concentrations (10-100 ng/ml) progressively increased binding above nadir levels. In the present studies, treatment of cultured immature Leydig cells with heparinase I and/or heparinase III, which enzymatically remove heparan sulfate proteoglycans, had no effect on basal binding of 125I-hCG to LH receptors or the decrease in binding due to treatment with low bFGF concentrations; however, this treatment dramatically reduced the secondary increase in binding following the addition of higher bFGF concentrations. These results strongly support the idea that the secondary increase in 125I-hCG binding to LH receptors elicited by treatment with higher bFGF concentrations is mediated by bFGF binding to heparan sulfate proteoglycans associated with the plasma membrane and/or extracellular matrix.

Evidence that biphasic effects of basic fibroblast growth factor on 5-ene-3 beta-hydroxysteroid dehydrogenase-isomerase activity in cultured immature Leydig cells are mediated by binding to heparan sulfate proteoglycans

The present studies examined the effects of heparin, heparinase, insulin or insulin-like growth factor-I on basic fibroblast growth factor actions on 5-ene-3 beta-hydroxysteroid dehydrogenase-isomerase activity of cultured immature rat Leydig cells. Treatment with basic fibroblast growth factor alone (0.025-20 ng/ml) for 2 days had a biphasic effect on enzyme activity, with lower concentrations (0.025-1 ng/ml) progressively inhibiting activity to approximately 20% of control, while higher concentrations (2.5-20 ng/ml) partially reversed the inhibitive effects. The inclusion of 10 micrograms/ml heparin, a concentration reported to inhibit growth factor binding to heparan sulfate proteoglycans, blocked the increase in enzyme activity elicited by higher growth factor concentrations, but had no effect on the progressive decline in activity due to lower concentrations. Concomitant treatment with heparinase I and III, which specifically hydrolyze heparan sulfate proteoglycans, had a similar effect. In addition, both insulin and insulin-like growth factor-I partially reversed the inhibition of enzyme activity due to treatment with 1 ng/ml basic fibroblast growth factor. These studies suggest that some basic fibroblast growth factor actions on cultured immature Leydig cells are mediated by binding to heparan sulfate proteoglycans, and that both insulin and insulin-like growth factor-I can reverse the inhibitive effects on 5-ene-3 beta-hydroxysteroid dehydrogenase-isomerase activity.

Cell blotting and isoelectric focusing of neuroblastoma-derived heparin-binding neurotrophic activities: detection of basic fibroblast growth factor protein and mRNA

Neuroblastoma cells have been shown to contain growth factors, which may be involved in the regulation of cell proliferation and/or differentiation. We have examined whether human IMR-32 neuroblastoma cells store factors with a capacity to promote neuron survival and differentiation. Heparin affinity chromatography, cell blotting, and isoelectric focusing of IMR-32 cell extracts revealed multiple neurotrophic activities at molecular weights of 16.8, 24.1, 39.0, 45.3, 52.3 and isoelectric points of 4.0, 5.0, 8.3, 9.0. Immunocytochemistry, immunoblotting, and radio-immunoassay with specific antibodies suggests that one neurotrophic activity is immunologically identical with basic fibroblast growth factor (bFGF). This assumption is supported by Northern blot analysis, which shows a 6.0 kb bFGF transcript.

Biphasic effect of basic fibroblast growth factor on 125I-human chorionic gonadotropin binding to cultured immature Leydig cells

The present studies examined the effects of basic fibroblast growth factor (bFGF or FGF-2) on 125I-human chorionic gonadotropin (hCG) binding to cultured immature rat Leydig cells. We found that low concentrations of bFGF (0.1-1.0 ng/ml) inhibited 125I-hCG binding to cultured immature Leydig cells in a dose- and time-dependent manner; however, this inhibition was reversed partially at higher bFGF concentrations (10-200 ng/ml). The decline in 125I-hCG binding by bFGF was due to a reduction in the number of binding sites per cell and not to a change in receptor affinity for the ligand. The inclusion of 10 micrograms/ml heparin (a concentration that is reported to block bFGF binding to heparan sulfate proteoglycans) with increasing bFGF concentrations had no effect on the inhibition of 125I-hCG binding by low bFGF concentrations, but completely blocked the secondary increase in binding by higher bFGF concentrations. In addition, neither varying heparin concentrations (0.1-25 micrograms/ml) nor insulin or insulin-like growth factor-I had any effect on the inhibition of 125I-hCG binding by 1 ng/ml bFGF. These studies suggest that receptor-mediated actions of bFGF (inhibition of hCG binding by low bFGF concentrations) on cultured immature Leydig cells are unaffected by heparin; however, the secondary increase in 125I-hCG binding observed with higher bFGF concentrations (mediated by bFGF binding to heparan sulfate proteoglycans) is blocked by heparin.

Transforming growth factor beta 1 and adrenocorticotropin differentially regulate the synthesis of adrenocortical cell heparan sulfate proteoglycans and their binding of basic fibroblast growth factor

Adrenocortical differentiated functions are under the control of both endocrine hormones such as ACTH and local factors such as transforming growth factor beta (TGF beta) or basic fibroblast growth factor (bFGF). Besides their regulatory actions on the synthesis of corticosteroids, these two classes of factors also exert some important effects on the cellular environment. We have examined here the regulation by ACTH and TGF beta of adrenocortical cell proteoglycan synthesis and secretion. Under basal conditions, adrenocortical cells synthesized and secreted several species of sulfated proteoglycans, 80% of them being recovered in solution in the culture medium. When analyzed by ion exchange chromatography, the cell extracts and the media from cells metabolically labeled with 35S-sulfate were found to contain two and three species of radioactive sulfated proteoglycans, respectively. All species were proteoheparan-sulfates. Treatment of adrenocortical cells with TGF beta 1 or ACTH resulted in a significant increase of the incorporation of 35S into both secreted and cell-associated proteoglycans. ACTH stimulated more than three times the amount of secreted proteoglycans eluting from DEAE-Trisacryl as peak B, whereas TGF beta preferentially increased the amount of peak C. No important modification of the size of the synthesized proteoglycans was observed. The subpopulation of heparan sulfate proteoglycans capable to bind bFGF was also largely increased after ACTH or TGF beta treatment and paralleled the variation in overall proteoheparan sulfate synthesis. Thus those effects of TGF beta and ACTH on proteoglycan synthesis may participate in an increased ability of adrenocortical cells to bind and respond to bFGF.

Evidence for basic fibroblast growth factor receptors in cultured immature Leydig cells

Previous studies have shown that basic fibroblast growth factor (bFGF) can modulate basal and luteinizing hormone/human chorionic gonadotropin (LH/hCG)-stimulated Leydig cell functions. It has not been ascertained whether these actions are due to direct or indirect effects on Leydig cells. To resolve this question, a multi-step procedure was used to isolate highly-purified Leydig cells from immature rats. 125I-bFGF binding studies were performed on cultured cells. Scatchard analysis of the data indicated a single binding site with an apparent Kd of 82 pM and a binding capacity of approximately 2800 sites per cell. Both bFGF and acidic FGF similarly were effective in displacing 125I-bFGF, suggesting that the receptor binds both bFGF and aFGF. However, neither hCG, follicle-stimulating hormone (FSH), insulin, insulin-like growth factor-1 (IGF-1), prolactin, platelet-derived growth factor (PDGF) or epidermal growth factor (EGF) were effective competitors. When binding studies were conducted on cultured testicular interstitial cellular fractions that are normally discarded during Leydig cell purification, bFGF receptors were identified in these fractions. These results demonstrate that bFGF can have direct effects on Leydig cells through specific receptors; however, because other interstitial cell type(s) also have bFGF receptors, they stress the importance of using highly purified cells when evaluating bFGF actions on Leydig cells.

Fibroblast growth factor reserves the bacterial retardation of wound contraction

Chronic granulating wounds were established in rats by excising burns inoculated with Escherichia coli. Recombinant human basic fibroblast growth factor was applied at dosages of 1, 10, and 100 micrograms/cm2 to the wounds of three groups of 20 animals on days 5, 9, 12, 15, and 18 after injury. The rate of wound closure was compared with that of similarly wounded animals treated with saline vehicle alone. High levels of bacteria caused significant retardation of wound contraction. The addition of basic fibroblast growth factor at the 100 micrograms/cm2 dosage level markedly improved the rate of wound closure whereas inert vehicles applied alone were ineffective. Since bacterial counts did not decrease in the basic fibroblast growth factor treated wounds, basic fibroblast growth factor was not inherently bactericidal. Histologic examination of the wounds treated with basic fibroblast growth factor showed increased cellularity with increased numbers of fibroblasts and round cells. These results suggest basic fibroblast growth factor can overcome the defect in healing created by bacterial infection, and this peptide may have efficacy in the management of the contaminated wound.

Never ending growth and a growth factor. I. Immunocytochemical evidence for the presence of basic fibroblast growth factor in a tapeworm

Basic fibroblast growth factor immunoreactivity (bFGF-IR) was detected in a specific set of nerve cells in the central nervous system of the gull-tapeworm Diphyllobothrium dendriticum (Cestoda)--an obligatory endoparasite. The long varicose processes of the bFGF-IR neurons extend along the two main nerve cords, which contain an actively growing population of nerve cells. A neurotrophic function for the bFGF-like material is proposed. The adult tapeworm lives in the intestine of a homeothermic host and has a pattern of very active and never ending growth. The larval stages live in poikilothermic hosts and grow very slowly. The bFGF-IR nerve cells occur both in II stage larvae and in adult worms. Thus, no correlation between the presence of bFGF-IR and the general growth rate of the worm was found. Western blot analysis revealed the presence of an anti-bFGF immunoreactive peptide with a molecular mass of 47 kDa in both larval and adult worms.

Appearance of malignant phenotype with partial loss of hormone dependency in androgen-dependent Shionogi Carcinoma 115 transfected with hst-1 gene

Shionogi Carcinoma 115 (SC 115) and Chiba Subline 2 (CS 2) are an androgen-dependent mouse tumor and an androgen-independent subline derived from SC 115, respectively. Since new expression of the transforming oncogene hst-1 might be related with autonomous progression in CS 2, the present study was designed to examine the influence of expression of hst-1 gene on SC 115. The transfectants of SC 115 with hst-1 still retained androgen sensitivity of growth, although the cells could grow without androgen. The transfectants, however, developed fibroblast-like appearance in the absence of androgen, in contrast to SC 115, which showed epithelial-like appearance after deprivation of androgen. The transfectants acquired an ability to form colonies in soft agar in the absence of androgen. SC 115 could not form tumors in intact mice, but the transfectants formed tumors at a high rate in male mice but not in female ones. From these results, it was concluded that expression of hst-1 was able to alter the phenotype of the androgen-dependent tumor with partial loss of androgen-dependency, and these changes might be advantageous for malignant progression.

Isolation and characterization of two different molecular forms of basic fibroblast growth factor extracted from human placental tissue

Basic fibroblast growth factor (bFGF) was purified to homogeneity from human placental tissue on a semi-large scale. Placental bFGF consists of two proteins of apparent molecular masses 16,000 and 18,000 dalton, as determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis under non-reducing conditions. Microsequence analysis showed that both proteins have the same N-terminal sequence Pro-Ala-Leu-Pro-Glu-Asp-Gly-Gly-Ser-Gly-Ala-Phe..., which is identical with that of (1-146) bFGF extracted from human brain. After reduction by dithiothreitol or mercaptoethanol, placental bFGF appears as a single protein of 16,000 dalton. The reduced protein displays the same ability to stimulate the proliferation of CCL39 fibroblasts as the non-reduced doublet. These data indicate that bFGF extracted from placental tissue consists of two proteins with different apparent molecular masses which do not differ in their N-terminal sequence but in their oxidation state.

Effect of bFGF on the inhibition of contraction caused by bacteria

Bacterial contamination of open wounds significantly inhibits wound contraction required in the healing process. Basic fibroblast growth factor (bFGF) has been shown to overcome contraction inhibition in wound-healing models impaired by diabetes or steroids. This study was designed to determine the effect of bFGF on wound contraction inhibition in an area contaminated with bacterial overgrowth. The topically applied bFGF reversed inhibition to wound contraction that normally occurs with bacterial contamination. This reversal does not appear to be due to increased collagen synthesis since bFGF has been shown to decrease collagen synthesis and the treated wounds showed no increase in breaking strength. The use of bFGF significantly decreased the number of days required for wound healing (P less than 0.01) despite active bacterial invasion and may be of value in the treatment of human contaminated wounds.

Proteoheparan sulfates contribute to the binding of basic FGF to its high affinity receptors on bovine adrenocortical cells

Bovine adrenocortical cells in primary culture express the basic fibroblast growth factor (bFGF) gene and their proliferation is stimulated by this growth factor. We report here the characterization of bFGF receptors on these cells. Binding studies revealed the presence of two bFGF receptor types: a limited number (4,300 sites/cell) of high affinity sites (Kd congruent to 2 pM) and a larger number (230,000 sites/cell) of lower affinity sites (Kd congruent to 400 pM). Cross-linking of 125I-bFGF to adrenocortical cells revealed two bands at 145 kDa and 125 kDa which are attributed to molecular complexes between the high affinity receptors and their ligand. These high affinity receptors possess N-linked carbohydrate chains that are important for proper cell surface expression but are devoid of glycosaminoglycan chains. The low-affinity (2 M NaCl-sensitive) binding sites are totally degraded by heparitinase treatment of adrenocortical cells indicating that low-affinity sites are borne by heparan sulfate proteoglycans. However, heparitinase treatment also reduced partially the binding of bFGF to high-affinity (2 M NaCl-resistant) sites. This argues for a contribution of heparan sulfate proteoglycans to the binding of bFGF to high-affinity receptors. Exogenous soluble heparin or heparan sulfate did not restore normal high affinity bFGF binding onto heparitinase-treated cells, suggesting that heparan sulfate proteoglycans either must be membrane-anchored or must contain specific structural features to enhance FGF binding to high-affinity receptors. Taken together with previous reports, this work supports the hypothesis that bFGF may act as an autocrine growth factor in the adrenal cortex.

Growth factor regulation of adrenal cortex growth and function

The control of adrenal cortex growth in vivo during development or under certain stress conditions is still very poorly understood at the molecular level. Some information can be collected however from in vitro experiments. Acidic and basic FGF appear to be the most potent mitogens, so far, for primary cultures of adult adrenocortical cells, whereas EGF can also stimulate growth of fetal cells. Several growth factors have emerged in the recent years as multifunctional molecules that play important regulatory functions on adrenocortical steroidogenesis. These include EGF, IL-1, insulin, IGF-1 and TGF beta. In certain cases (e.g. IGF-1, TGF beta), these factors participate in autocrine loops of regulation. The differential expression, release and activation of these factors might locally regulate the steroidogenic action of the hormonal signals delivered through the hypothalamo-pituitary-adrenal axis.

Endothelin releasing activity in calf serum and porcine follicular fluid

Bovine calf serum (CS) and porcine follicular fluid (PFF) added to bovine aortic endothelial cells (BAEC) in culture stimulate endothelin (ET) release. Sorbent extraction of acidified calf serum and PFF using Bond Elut C18 yields a product with an activity 30% that of the starting material. Fractionation of Bond Elut C18 extracted CS or PFF using HPLC yields peaks of activity with retention times similar to those of TGF beta and activin A, respectively. TGF beta is 10-fold more potent than activin A to stimulate ET release from BAECs. The observation that TGF beta and activin A are dose-additive but not effect-additive to stimulate ET release is compatible with the conclusion that these two substances act through a similar mechanism. Thus, TGF beta and/or activin A-related peptides may contribute to the ET releasing activity observed in acidified Bond Elut C18 extracted CS and PFF. The identity of ET-releasing activity in native CS and PFF remains to be established.

Acidic fibroblast growth factor (aFGF) is present in the fluid of brain tumour pseudocysts

Fluid samples from brain tumour pseudocysts were examined for the presence of Fibroblast Growth Factor (FGF). Fluids were collected from 6 patients with differentiated low grade gliomas (group A), 3 anaplastic gliomas (group B) and 3 metastases (group C). For FGF assays pooled fluids from group A, B, and C were subjected to affinity chromatography on a Heparin-Sepharose column. Each pool contained endothelial cell mitogenic activity which eluted in the 1.2 M NaCl fraction and to a lesser degree in the 0.6 M fraction of Heparin-Sepharose high affinity chromatography. Mitogenic activity in the 1.2 M NaCl fraction of Heparin-Sepharose chromatography suggests the presence of acidic FGF (aFGF).