Neurotrophic effects of basic and acidic fibroblast growth factors are not mediated through glial cells

Basic and acidic fibroblast growth factors (bFGF, aFGF) increase the survival of fetal hippocampal pyramidal neurons in serum-free cultures. bFGF is also a mitogen for astrocytes either in highly purified glial cultures or as a contaminant in neuronal cultures. The possibility that bFGF enhances neuronal survival indirectly through stimulating glial proliferation is unlikely. In the presence of 1 ng/ml bFGF, the total number of contaminating astrocytes (as defined by immunohistochemical staining for glial fibrillary acidic protein (GFAP] was increased to 4.3% vs 0.9% in control hippocampal cultures. aFGF did not significantly increase astrocyte number while supporting neuronal survival. Two other agents which stimulated equal or greater astrocytic proliferation, epidermal growth factor (EGF) and 10% serum, did not support neurons, and bFGF still significantly increased neuronal survival in their presence. When glial proliferation was inhibited by aphidicolin, contamination decreased to 0.1% in controls and 1.0% with 1 ng/ml bFGF, yet the neurons remained responsive to FGF. Cultures lacking any detectable GFAP-positive cells were identified, and even in the absence of glial cells, aFGF and bFGF increased neuronal survival. Because there is no significant correlation between the neuronal response and astrocyte number, it appears that bFGF and aFGF can directly support neuronal survival.

Receptor- and heparin-binding domains of basic fibroblast growth factor

Two functional domains in the primary structure of basic fibroblast growth factor (FGF) have been identified on the basis of their ability to interact with the FGF receptor, bind radiolabeled heparin, and modulate the cellular response to FGF. Peptides derived from these two functional domains can act as partial agonists and antagonists in biological assays of FGF activity. Peptides related to the sequences of FGF-(24-68)-NH2 and FGF-(106-115)-NH2 inhibit thymidine incorporation into 3T3 fibroblasts when they are stimulated by FGF but have no effect when the cells are treated with either platelet-derived growth factor or epidermal growth factor. They also possess partial agonist activity and can stimulate DNA synthesis when tested in the absence of exogenous FGF. The active peptides have no effect on the binding of epidermal growth factor to its receptor on A431 cells and they can modulate the effects of FGF, but not fibronectin, on endothelial cell adhesion. The results suggest the possibility of designing specific analogs of FGF that are capable of inhibiting the biological effects of FGF.

Induction of c-fos, calcitonin gene expression, and acidic fibroblast growth factor production in a multipeptide-secreting neuroendocrine cell line

The multipeptide-secreting 44-2C cell line maintains differentiated function when grown in a serum-free, growth factor- and hormone-deprived milieu. The cells continue to synthesize and secrete calcitonin (CT), CT gene-related peptide, neurotensin, and somatostatin and respond to cellular secretagogues such as GRF and acidic and basic fibroblast growth factor. We designed experiments to ascertain the functional role(s) of cellular factors involved in the maintenance of the differentiated state in 44-2C cells. We report here the phenotypic transformation that occurs in these cells in the course of adjustment to the serum-free state. We also show the differential increase in CT-specific mRNA, the transient induction of c-fos, and the characterization of biologically active acidic fibroblast growth factor.

An in vivo model for study of the angiogenic effects of basic fibroblast growth factor

We have investigated the angiogenic effects of basic fibroblast growth factor following its implantation in slow release beads under the kidney capsule. The presence of basic fibroblast growth factor in the subcapsular space induced a marked angiogenic response maximal at 1 microgram dose per kidney. Histological examination at the site of treatment failed to reveal evidence of an inflammatory response, thus supporting the observation that basic fibroblast growth factor alone can stimulate in vivo neovascularization. Beads pretreated with saline or with human growth hormone had no angiogenic effect. Because of the readily accessible location in the retroperitoneal space, the ease of drug delivery, and the marked vascular proliferation seen in response to FGF, our results suggest that the kidney capsule is an excellent model for study of the physiological role played by FGF and related peptides in promoting angiogenesis in vivo.

The inhibition of low density lipoprotein metabolism by transforming growth factor-beta mediates its effects on steroidogenesis in bovine adrenocortical cells in vitro

Transforming growth factor-beta (TGF beta) has a differential effect on the growth and function of bovine adrenocortical cells in vitro. TGF beta inhibits basal as well as ACTH- or angiotensin II-stimulated steroid formation, with no evidence of change in cell growth. The major inhibitory effect of TGF beta occurs at a step before cholesterol formation, since treatment of adrenocortical cells with TGF beta decreased not only delta 4-steroid levels but also delta 5-steroid levels. The addition of cholesterol reverses the suppression of steroidogenesis induced by TGF beta. To determine the mechanism of this inhibition, the effect of TGF beta on low density lipoprotein (LDL) metabolism was investigated. Cells treated with TGF beta showed a significant suppression of [125I]iodohuman LDL ([125I]LDL) binding to the cell surface, followed by decreases in internalization and proteolytic degradation of [125I]LDL. Maximal inhibition of LDL metabolism was observed at a concentration of 1 ng/ml (4 X 10(-11) M) TGF beta. The stimulation of LDL metabolism by ACTH was also inhibited by TGF beta, and the inhibition observed correlated well with the inhibition of steroidogenesis. The inhibitory effect of TGF beta on [125I]LDL binding results from the decrease in the maximal LDL-binding capacity. The stimulation of LDL uptake induced by Bu2cAMP, cholera toxin, forskolin, and Ang II was also decreased by treatment with 1 ng/ml TGF beta. The specificity of this effect is quite high, since the inhibitory effects of TGF beta on LDL metabolism were not observed with either inhibin A or activin, two molecules that have considerable structural homology to TGF beta. We conclude that TGF beta specifically suppresses LDL metabolism in bovine adrenocortical cell cultures and that this step may mediate, at least in part, its role as a potent inhibitor of steroidogenesis.

Multiple influences of a heparin-binding growth factor on neuronal development

Heparin-binding growth factor-2 (HBGF-2; also known as basic fibroblast growth factor) is mitogenic for most anchorage-dependent cells. It is shown here that HBGF-2 stimulates cell-substratum adhesion and neurite extension in the sympathetic nerve cell line PC12. When HBGF-2 is adsorbed to artificial extracellular matrices consisting of heparin or chondroitin sulfate, it causes the formation of cellular aggregates or circles of cells, respectively. HBGF-2 is also a nerve cell survival molecule, for it potentiates the survival of primary cultures of embryonic chick ciliary ganglion cells but not of embryonic neural retina cells. Finally, a series of synthetic peptides from the HBGF-2 sequence is described that selectively alter the biological effects of HBGF-2. The amphiphilic nature of one of these peptides is discussed with respect to its ability to stimulate cell adhesion.

Isolation and partial characterization of basic fibroblast growth factor from bovine testis

A basic fibroblast growth factor (FGF) has been purified to homogeneity from bovine testis, using ammonium sulfate precipitation of the crude extract followed by three chromatographic steps, involving cation-exchange, heparin-Sepharose, and reversed-phase HPLC. Gas-phase sequence analysis showed the amino-terminal amino acid sequence of the isolated polypeptide as His-Phe-Lys-Asp-Pro-Lys-Arg-Leu-Tyr-, which is identical to the amino-terminal of the (16-146) fragment of basic FGF previously characterized from corpus luteum, adrenal, and kidney. The purified FGF was shown to have the same biological activity as that of basic FGF (1-146). This finding suggests that basic FGF is present in testis and may act as a local regulator of testicular function. In addition, testicular FGF might play an important role in spermatogenesis and/or the development of testis.

Fibroblast growth factors are present in the extracellular matrix produced by endothelial cells in vitro: implications for a role of heparinase-like enzymes in the neovascular response

Salt extracts of the extracellular matrix (ECM) that is produced by vascular and capillary endothelial cells contain mitogens that are indistinguishable from basic and acidic fibroblast growth factors (FGFs). The biological activity found in these extracts is retained by heparin-Sepharose affinity columns and elutes with salt concentrations similar to those required to elute FGFs (i.e. 1.1 - 2M NaCl). Antisera raised against synthetic fragments of basic and acidic FGF crossreact with the ECM-derived mitogens. Radioiodinated basic FGF binds to the ECM formed by both vascular and capillary endothelial cells, a result that is consistent with the observation that FGF-like mitogens are found on the ECM. The binding of FGF to the ECM is negligible when the ECM has been pretreated with heparinase or heparitinase suggesting that the mitogen is interacting with a heparin-like glycosaminoglycan in the ECM. The digestion of the ECM with several grades of hyaluronidase, chondroitinase or chondro-4-sulfatase or chondro-6-sulfatase has little or no effect on 125I-FGF binding to the ECM. In view of the fact that many, if not all cells, produce heparan sulfates and that these glycosaminoglycans are associated with the external surface of the cell and the ECM, a model is proposed suggesting that the neovascular response induced by tumours and some normal tissues may be mediated at least in part, by the initial release of heparinase-like enzymes rather than angiogenic factors (FGFs) per se. The release of these enzymes would effectively mobilize a secondary local release of FGF from the ECM which then induces a proliferative response.

Distribution of fibroblast growth factors (FGFs) in tissues and structure-function studies with synthetic fragments of basic FGF

Acidic and basic fibroblast growth factors (FGFs) are characterized by their high affinity for heparin and their capacity to stimulate angiogenesis in vivo. While both molecules are structurally distinct they have 53% homology in their primary sequence and exist in similar molecular forms. These heparin-binding growth factors are also characterized by a wide distribution, a characteristic that may be attributable, at least in part, to their production by endothelial cells and their storage in the extracellular matrix. Structure-function studies with synthetic fragments of basic FGF have identified two peptidic sequences that cross-react with FGF receptor and that can modulate the cellular response to basic FGF. Both functional domains bind radiolabeled heparin, inhibit cell growth, and can interfere with stimulation of neurite outgrowth, cell adhesion, and differentiated cell function. The possible application of these antagonists to defining the role of FGF in wound repair, nerve regeneration, and vascularization of the vasovasorum is discussed.

bFGF is the putative natural growth factor for human melanocytes

Normal human melanocytes, unlike pigment cells from metastatic melanomas, do not survive in culture in routine, serum-supplemented media. The search for natural growth factors for melanocytes has shown that mitogenic activity is ubiquitous in several tissues and in melanomas. Of several known growth factors tested, basic fibroblast growth factor (bFGF) was the only one mitogenic for melanocytes but only in the presence of cyclic-adenosine-monophosphate (cAMP) stimulators. The mitogenic activity toward melanocytes in tissues and melanoma cell extracts had high affinity for heparin and antibodies to bFGF synthetic peptides. These results suggest that one of the growth factors for melanocytes might be bFGF or a bFGF-like polypeptide and that autocrine production of bFGF-like molecules by melanoma cells may contribute to the malignant phenotype of melanocytes. Because acidic FGF (aFGF) did not stimulate growth, the receptors for bFGF on melanocytes might be significantly different from those for a FGF.

Fibroblast growth factor as an intraovarian hormone: differential regulation of steroidogenesis by an angiogenic factor

The potential role of fibroblast growth factor (FGF) in the regulation of granulosa cell differentiation was investigated because of its recent identification as the corpus luteum angiogenic factor. Treatment of rat ovarian granulosa cells with FGF inhibits the capacity of follicle stimulating hormone to stimulate estrogen production and to induce luteinizing hormone receptors. In contrast, although incubations with FGF can inhibit the estrogen-sensitive component of progesterone synthesis, the presence of FGF with suboptimal concentrations of follicle stimulating hormone significantly enhances the synthesis of progesterone. This capacity to differentially regulate steroidogenesis in the granulosa cell is comparable to the potency of FGF (ED50 = 30 pg/ml, 10(-12) M) in other in vitro assays. The observation that an angiogenic factor, like FGF, can specifically increase the sensitivity of progesterone synthesis and simultaneously inhibit estrogen formation supports the hypothesis that this growth factor plays an important role in the development and maintenance of a functional corpus luteum. As such, FGF may be involved in the local regulation of follicular selection, growth and atresia by simple virtue of its capacity to induce a neovascular response on one hand and by its ability to modulate the differentiated response to gonadotropins on the other.

Purification and partial characterization of a mitogenic factor from bovine liver: structural homology with basic fibroblast growth factor

Two mitogenic peptides in bovine liver extract were purified to apparent homogeneity by monitoring the purification steps with two in vitro bioassays; one based on stimulation of adult bovine aortic arch endothelial cell proliferation and the other incorporation of [3H]thymidine to mouse fibroblast 3T3 cells. The purification procedure involved cation-exchange chromatography followed by affinity chromatography on heparin-Sepharose and two steps of reversed-phase HPLC. The purified material showed the same biological activity as pituitary basic fibroblast growth factor (FGF). Amino acid analyses of the purified mitogen yielded a similar, but not identical composition to that of bovine pituitary basic FGF(1-146) reported previously. Gas-phase microsequencing identified two sequences in equal amounts in the purified preparation. Furthermore, the sequencing results are in accord with the theoretical data obtained when two truncated forms of basic FGF, corresponding to FGF(12-146) and (16-146), are being sequenced simultaneously. Basic FGF(12-146) is a novel truncated form of basic FGF which has not been isolated before although the (16-146) fragment has been found previously in kidney, corpus luteum, and adrenal. SDS-PAGE analysis could not separate the two forms and showed that both migrated as a protein of about 15,100 daltons, which is slightly smaller than intact basic FGF(1-146) (16,200 daltons). These results, taken together, indicate that at least some of the mitogenic activity in liver may be derived from basic FGF-related polypeptides.

Differential effects of transforming growth factor type beta on the growth and function of adrenocortical cells in vitro

Transforming growth factor type beta (TGF-beta) suppresses basal as well as corticotropin (ACTH)-stimulated steroid formation by bovine adrenocortical cells in culture. The effect is dose dependent and is not accompanied by any change in adrenocortical cell growth. The minimum effective dose of TGF-beta is 4 X 10(-13) M (10 pg/ml), and maximal inhibition is observed at a concentration of 4 X 10(-11) M (1 ng/ml). A 16- to 20-hr incubation with TGF-beta is required to decrease steroidogenesis, and 12-18 hr are required before cells treated with TGF-beta recover complete responsiveness to corticotropin. Increases in cAMP mediated by corticotropin, forskolin, and isobutylmethylxanthine are not modified by the addition of TGF-beta; thus adenylate cyclase activity is unaffected by TGF-beta. Although TGF-beta inhibits the formation of all of the delta 4-steroids measured (including cortisol, corticosterone, aldosterone, and androstenedione), its effect can be completely reversed by the addition of 25-hydroxycholesterol, pregnenolone, or progesterone to the cells. In contrast, the addition of low density lipoprotein has no effect suggesting that TGF-beta targets the conversion of cholesterol precursors to cholesterol. The results demonstrate a highly potent effect of TGF-beta on the differentiated function of the adrenocortical cell. The inhibition of steroidogenesis can be dissociated from any effect on cell proliferation, and it occurs distal to the formation of cAMP but proximal to the formation of cholesterol. The results suggest that in the adrenal, TGF-beta or TGF-beta-like proteins may be playing an important role in modifying the differentiated state of the adrenocortical cell.

Basic fibroblast growth factor induces angiogenesis in vitro

Fibroblast growth factors (FGFs) are potent mitogens for vascular and capillary endothelial cells in vitro and can stimulate the formation of blood capillaries (angiogenesis) in vivo. A crucial event in this process is the invasion of the perivascular extracellular matrix by sprouting endothelial cells. Using a recently developed in vitro model of angiogenesis, we show here that highly purified basic pituitary FGF can induce capillary endothelial cells to invade a three-dimensional collagen matrix and to organize themselves to form characteristic tubules that resemble blood capillaries. We also show that basic FGF concomitantly stimulates endothelial cells to produce a urokinase-type plasminogen activator, a protease that has been implicated in the neovascular response. The results demonstrate that basic FGF can stimulate processes that are characteristic of angiogenesis in vivo, including endothelial cell migration, invasion, and production of plasminogen activator.

Isolation of an amino terminal extended form of basic fibroblast growth factor

Extraction of bovine pituitaries in the presence of enzyme inhibitors (2 mM PMSF, 2 mM sodium tetrathionate, 15 microM pepstatin A, and 1 mM EDTA) resulted in the isolation of two distinct forms of basic fibroblast growth factor. Partial characterization of both molecules showed one form to be identical to basic FGF(1-146) which has already been reported by our laboratory. The second form was estimated by SDS-PAGE to have a molecular weight of 17,000 Daltons which is slightly larger than that of basic FGF(1-146). Amino acid analysis shows the presence of 8 new residues more than basic FGF(1-146) which accounts for the difference in molecular weight. Gas-phase sequencing of this molecule indicated that it bears a blocked amino terminus. Furthermore, this higher molecular weight form of basic FGF did not show immunoreactivity with antibodies specific for the amino terminus of basic FGF(1-146) but cross reacted with antibodies generated against midportion fragments of basic FGF(1-146), indicating that the molecule is amino terminally extended. Like basic FGF(1-146), the molecule is a potent mitogenic factor for vascular endothelial cells. Taken together these results demonstrate the existence of a precursor form of basic FGF which is extended by 8 residues at the amino terminus with the first residue being blocked.

Inhibition of endothelial cell proliferation by type beta-transforming growth factor: interactions with acidic and basic fibroblast growth factors

TGF beta is a potent (ED50 approximately 10(-11) M) inhibitor of the proliferative activities of both acidic and basic FGF on vascular and capillary endothelial cells in vitro. The inhibition of cell growth is dose-dependent and characteristic of a non-competitive interaction. The results demonstrate that TGF beta and FGF can interact at the cellular level to modulate growth and suggest that many of the biological activities of FGF observed in vitro and in vivo (ie angiogenesis, cell growth, cell differentiation) may be regulated by the presence of TGF beta and related proteins (ie inhibin) in the local cellular milieu. The possible identity of TGF beta with the inhibitors of endothelial cell growth detected in in vitro assays of crude extracts is discussed.

A prospective comparison of gentamicin and metronidazole and moxalactam in the prevention of septic complications associated with elective operations of the colon and rectum

Bacteriologic evidence suggests that Latamoxef (moxalactam) is effective against colonic bacteria which cause infection during colonic and rectal operations. In a prospective comparative study, 86 patients undergoing colorectal operations were randomized to receive intravenously 24 hour antibiotic cover with either gentamicin and metronidazole or moxalactam. Six patients (13 per cent) in the gentamicin and metronidazole group and five (12 per cent) in the moxalactam group had wound sepsis develop. Perineal wound sepsis (31 per cent) was significantly more common than abdominal wound sepsis (7 per cent). No complications were noted from the use of moxalactam. No clinical evidence of abnormal bleeding was seen and the results of studies on coagulation and platelet function postoperatively were normal. The results suggest that moxalactam provides effective, safe prophylaxis comparable with established antibiotic combinations in patients undergoing colorectal operations.

The molecular weight forms of rat growth hormone secreted in response to growth hormone-releasing factor

The different molecular weight forms of immunoreactive growth hormone (irGH) secreted by the anterior pituitary of rats were evaluated during basal and stimulated secretion in vitro and in vivo. Anterior pituitary cells maintained in a monolayer culture system secreted only a 22,000-Da form of GH based on Sephacryl S-200 column chromatography. This was also true for the irGH secreted in response to growth hormone-releasing factor and prostaglandin E2 stimulation. In contrast, the molecular weight forms of irGH found in plasma under basal conditions included an approximately 90,000-Da form as well as the expected 22,000-Da form. The concentrations of both forms increased following growth hormone-releasing factor stimulation although there was a shift in the ratio of the forms secreted. These results suggest that the larger molecular weight forms of rat GH observed in plasma may be the result of some postsecretory process which occurs in blood and suggests a possible regulatory function for the larger molecular weight forms as it pertains to the bioavailability of GH in vivo.

Fibroblast growth factor promotes survival of dissociated hippocampal neurons and enhances neurite extension

Basic fibroblast growth factor (FGF) has been found to increase neuronal survival and neurite extension in a highly purified population of fetal rat hippocampal neurons under well-defined serum-free cell culture conditions. In the presence of FGF, neuronal survival after 7 days in culture on a simple plastic substrate is increased 4-fold, to 54% of the initial population. Survival is increased 2-fold to 40% on polyornithine-laminin. When FGF was bound to plastic or heparin substrates, neurite outgrowth was significantly increased to lengths comparable to those seen with laminin; however, FGF produced no further increase in neurite outgrowth on laminin. Half-maximal survival was observed at FGF concentrations of about 15 pg/ml (1 pM); half-maximal process outgrowth occurred at about 375 pg/ml (20 pM). The responsive cells were identified as neurons by their labeling with tetanus toxin and by antibodies to neurofilaments and to the neuron-specific enolase. Astrocytes, identified by the presence of glial fibrillary acidic protein, constituted about 10% of cells present at 1 week both in the presence and in the absence of FGF. These results strongly suggest that, in addition to its known mitogenic effects on nonneuronal cells, FGF possesses neurotrophic activity for hippocampal neurons.

Type beta transforming growth factor (TGF-beta) is a potent stimulator of the basal secretion of follicle stimulating hormone (FSH) in a pituitary monolayer system

In view of striking similarities between TGF-beta and inhibin, we investigated the possibility that TGF-beta might modulate pituitary hormone release in vitro. Long term incubations of beta transforming growth factor (TGF-beta) with rat anterior pituitary cells for 48 hr stimulates the basal secretion of FSH in a dose-dependent manner. The secretion of LH, TSH, GH, ACTH and PRL is not modified by TGF-beta. The minimal effective concentration of TGF-beta is 10 pg/ml (less than 500 attomolar) and is dose dependent over a range from 1 pg to 10 ng/ml. Treatment of cells with TGF-beta for short incubation times (4 hr) in assays similar to that used for hypophysial releasing factors is not effective, indicating that TGF-beta acts through a cellular mechanism distinct from that of LRF. Inhibin-A, recently characterized on the basis of its capacity to specifically inhibit the secretion of FSH in the 48 hr bioassay system inhibits the stimulatory effect of TGF-beta on FSH-release. Analyses of the dose response curves indicate that the interaction occurs in a typical non-competitive manner. The results suggest that a TGF-beta-like molecule, present in follicular fluid, may be responsible for the FSH-releasing activity ("anti-inhibin" activity) observed by us and others during the process of isolating inhibin from follicular fluids. They also suggest an important role for inhibin and the TGF-beta related molecules in modulating pituitary gonadotropin release.

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

The angiogenic growth factors present in the bovine adrenal gland have been purified by a combination of differential salt precipitation, ion exchange chromatography, and heparin-Sepharose chromatography. They consist of 2 single chain polypeptides with apparent mol wt of 16,000 and 15,000. Sequence analysis of the first 14 residues of both peptides identified the sequences as Pro-Ala-Leu-Pro-Glu-Asp-Gly-Gly-Ser-Gly-Ala-Phe-Pro-Pro for 1 of the peptides and His-Phe-Lys-Asp-Pro-Lys-Arg-Leu-Tyr-x-Lys-Asn-Gly-Gly for the other. The first sequence is identical to residues 1-14 of bovine pituitary and brain fibroblast growth factor (FGF), while the second is identical to residues 1-14 of the corpus luteum (CL) FGF, which is an amino-terminally truncated form of FGF and is otherwise similar, if not identical, to FGF. The biological activity of adrenal FGF is indistinguishable from that of pituitary or brain FGF and CL FGF. They are highly active in triggering the proliferation of culture bovine vascular endothelial cells derived from either large vessels (aortic arch) or CL and adrenal cortex capillaries (half-maximal stimulation at 20-40 pg/ml and saturation at 400-600 pg/ml). In vivo implants containing 50 ng to 1 microgram adrenal-derived growth factors stimulate neovascularization in the chorioallantoic membrane of the chick embryo. In addition to being mitogenic for vascular endothelial cells, adrenal FGFs stimulate the proliferation of a wide variety of mesoderm- and neuroectoderm-derived cells, including vascular smooth muscle cells, granulosa and adrenal cortex cells, rabbit costal chondrocytes, and corneal endothelial cells.

Relative potencies of human, rat, bovine/caprine, porcine and ovine hypothalamic growth hormone-releasing factors to release growth hormone by the rat anterior pituitary in vitro

Synthetic rat, human, bovine/caprine, porcine and ovine growth hormone-releasing factor (GRF) were tested for their capacity to release growth hormone (GH) by the rat anterior pituitary in vitro. All peptides elicited parallel and dose-dependent increases in GH release and produced similar maximal GH secretion. Rat GRF was 3-6 times more potent in stimulating the release of GH than all other GRFs, while human, bovine/caprine, porcine and ovine GRF had potencies that were not statistically different. The increased potency of both rat GRF(1-27)NH2 and rat GRF(1-23)NH2 when compared to human GRF(1-27)NH2 and human GRF(1-23)NH2, respectively, suggests that the increased potency of this molecule resides in structural differences in the amino terminal of native GRF. The results demonstrate increased sensitivity of rat pituitary cells for their homologous releasing factor.

Immunoreactive fibroblast growth factor (FGF) in a transplantable chondrosarcoma: inhibition of tumor growth by antibodies to FGF

Using a radioimmunoassay for bovine pituitary fibroblast growth factor (FGF), we have established the presence of the immunoreactive mitogen in extracts of a transplantable mouse chondrosarcoma. Both neutral and acidic extracts of the tumor contain an immunoreactive FGF (ir-FGF) that cross-reacts in a parallel and dose-dependent fashion in the radioimmunoassay. The ir-FGF is retained on heparin-Sepharose affinity columns and can be detected in the same molecular weight forms as rat pituitary FGF. Mice (C57/Bl) inoculated with the tumor (10 mg, im) show a decreased rate of tumor growth when passively immunized with the antiserum to FGF. The results establish the presence of FGF in this tumor and implicate its role in the etiology of its development.

Growth hormone-releasing factor: a new chapter in neuroendocrinology

The isolation and characterization of growth hormone-releasing factor (GRF) has initiated a new and exciting era in our understanding of the neuroendocrine regulation of pituitary growth hormone (GH) secretion. This report briefly describes the isolation and characterization of GRF, factors which modulate the GH response to GRF and the effects of chronic administration and deprivation of GRF on somatic growth. The intent of this report is to serve as a general introduction on biochemical and physiological aspects of GRF. The following reports from this symposium will then cover many of these topics in much greater detail.

Immunohistochemical evidence that growth hormone-releasing factor (GRF) neurons contain an amidated peptide derived from cleavage of the carboxyl-terminal end of the GRF precursor

Antisera were raised against synthetic replicates of the carboxyl-terminal (C-terminal) fragment of the precursor to human GH-releasing factor (GRF) (pre-proGRF) whose structure was predicted from the complementary DNA cloned from a pancreatic tumor. These antisera were used along with antisera to human GRF itself to search for the presence of related molecules in the human hypothalamus, with an immunohistochemical approach. The antisera to pre-proGRF that recognize specifically the C-terminal amidated form of pre-proGRF stain GRF neurons in their cell bodies, fibers, and nerve endings that are in contact with portal capillaries of the median eminence. Antisera against the nonamidated form of the molecule did not give any staining in the hypothalamus. These results strongly suggest that human hypothalamic GRF derives from a precursor immunologically related (and probably identical) to the tumorous one and that this precursor is cleaved inside GRF cell bodies to give, in addition to the GRF-44-NH2 a second amidated peptide, the C-terminal pre-proGRF that is transported distally to nerve endings and most probably coreleased with GRF into portal capillaries.

Retina- and eye-derived endothelial cell growth factors: partial molecular characterization and identity with acidic and basic fibroblast growth factors

Two retina-derived growth factors have been isolated on the basis of their ability to stimulate the proliferation of capillary endothelial cells in vitro. Gas-phase sequence analysis identified the amino-terminal sequence of the major form of the mitogen as being identical with residues 1-35 of bovine basic fibroblast growth factor (FGF). Amino-terminal sequence analysis of the second form identified 28 residues that are indistinguishable from those of brain acidic FGF (residues 1-28). The possibility that these retina-derived endothelial cell growth factors are related to, if not identical with, basic and acidic FGF is supported by observations that they have similar molecular weights (15000-16000), similar retention behavior on all steps of chromatography (ion-exchange, heparin-Sepharose), and similar amino acid compositions and that they cross-react with antibodies to basic and acidic FGF. The eye-derived growth factors, like FGF, are potent stimulators of capillary endothelial cell growth in vitro. The results identify the major retina-derived endothelial cell growth factor as indistinguishable from basic FGF and demonstrate the presence of an acidic FGF in the eye. They suggest that at least some of the mitogenic, angiogenic, and neovascularizing activities described as being present in the retina are due to the existence of FGF in this tissue. The implications of this finding on the etiology and pathophysiology of vasoproliferative diseases of the eye are discussed.

Primary structure of bovine brain acidic fibroblast growth factor (FGF)

The major anionic mitogenic polypeptide for endothelial cells, acidic fibroblast growth factor (FGF), has been purified to homogeneity from bovine brain and its complete primary structure established by gas-phase sequence analysis. The 140 amino acid (Mr 16,000) protein has been previously shown to be a potent growth factor for many diverse cell types of mesodermal origin, in vitro, and an angiogenic agent, in vivo. The amino acid sequence of bovine brain acidic FGF has a 53% absolute homology with that of bovine pituitary basic FGF suggesting that these endothelial cell mitogens are derived from a single ancestral gene.

Corpus luteum angiogenic factor is related to fibroblast growth factor

An angiogenic growth factor present in bovine corpus luteum (CL) has been purified to apparent homogeneity by a combination of differential salt precipitation, ion exchange chromatography, and heparin-Sepharose chromatography. It is a single chain polypeptide with an apparent mol wt of 15,000 and an amino acid composition similar to that previously reported for pituitary and brain fibroblast growth factor (FGF). Sequence analysis of the first 17 residues of the CL-derived growth factor identified the sequence; His-Phe-Lys-Asp-Pro-Lys-Arg-Leu-Tyr-X-Lys-Asn-Gly-Gly-X-Phe-Leu. This sequence is identical to residues 16-33 of bovine pituitary and brain FGF, indicating that the CL-derived growth factor is an amino-terminally truncated form of FGF and is otherwise similar, if not identical, to FGF. The biological activity of CL FGF is indistinguishable from that of pituitary or brain FGF. It is highly active in triggering the proliferation of cultured bovine vascular endothelial cells derived either from large vessels (aortic arch) or from corpus luteum and adrenal cortex capillaries (half-maximal stimulation at 20-40 pg/ml and saturation at 400-600 pg/ml). In vivo implants containing 50 ng to 1 microgram CL-derived growth factor stimulate neovascularization in the chorioallantoic membrane of the chick embryo. In addition to being mitogenic for vascular endothelial cells, CL FGF also stimulates the proliferation of a wide variety of mesoderm- and neuroectoderm-derived cells, including vascular smooth muscle cells, granulosa and adrenal cortex cells, rabbit costal chondrocytes, and corneal endothelial cells.

Isolation and partial characterization of an endothelial cell growth factor from the bovine kidney: homology with basic fibroblast growth factor

Two kidney-derived mitogens have been isolated by ion exchange, heparin-Sepharose and reverse-phase high-performance liquid chromatography on the basis of their capacity to stimulate the proliferation of bovine vascular endothelial cells in vitro. Gas phase sequence analysis identified the amino terminal sequences His-Phe-Lys-Asp-Pro-Lys-Arg-Leu-Tyr-X-Lys-Asn-Gly-Gly-Phe-Phe-Leu and His-Phe-Lys-Asp-Pro-Lys-Arg-Leu, respectively. The sequences are identical to residues 16-32 and 16-23 of bovine basic pituitary Fibroblast Growth Factor (FGF). The possibility that these kidney-derived mitogens are related, if not identical, to pituitary basic FGF is supported by the observations that they have similar molecular weights (15-16 kDa), similar retention behavior on all steps of chromatography and similar amino acid compositions, and they share at least some structural homology. Moreover, the kidney-derived growth factors, like basic FGF, are potent stimulators of capillary endothelial cells, granulosa cells, adrenocortical cells and vascular smooth-muscle cells (ED50 = 50 pg). The results demonstrate the existence of a kidney-derived FGF and suggest that at least some of the mitogenic, angiogenic and neovascularising activities described to be present in the kidney are due to the presence of an FGF-like molecule in this tissue.

Primary structure of bovine pituitary basic fibroblast growth factor (FGF) and comparison with the amino-terminal sequence of bovine brain acidic FGF

The two major mitogenic polypeptides for endothelial cells have been purified to homogeneity. The complete primary structure of bovine pituitary basic fibroblast growth factor (FGF) and the amino-terminal amino acid sequence of bovine brain acidic FGF have been established by gas-phase sequence analyses. Homogeneous preparations of these polypeptides are potent mitogens (basic FGF, ED50 approximately equal to 60 pg/ml; acidic FGF ED50 approximately equal to 6000 pg/ml) for many diverse cell types including capillary endothelial cells, vascular smooth muscle cells, and adrenocortical and granulosa cells; in vivo, basic FGF is a powerful angiogenic agent in the chick chorioallantoic membrane assay. The available protein sequence data demonstrate the existence of significant structural homology between the two polypeptides.

Immunoreactive and biologically active growth hormone-releasing factor in the rat placenta

Rat placentas from fetuses of 18 and 20 days of gestation were collected, extracted, and examined for their capacity to stimulate GH release in vitro. The crude extract stimulated, in a dose-dependent fashion, GH release by rat anterior pituitary cells in monolayer culture. The biological and immunological activities retained on antirat GH-releasing factor immunoaffinity columns eluted on Sephadex G-75 (fine) columns with an estimated mol wt of 5000 daltons. Reverse phase HPLC of this material revealed the presence of two forms of GRF activity that eluted with retention times identical to those of synthetic rat GRF and its methionine sulfoxide counterpart [Met(O)27]GRF. The results demonstrate the presence of an immunoreactive and biologically active GRF in the rat placenta that is indistinguishable from rat hypothalamic GRF.

A nonmitogenic pituitary function of fibroblast growth factor: regulation of thyrotropin and prolactin secretion

The addition of fibroblast growth factor (FGF) to primary cultures of rat anterior pituitary cells modifies their response to thyrotropin-releasing factor in a dose-dependent manner. While the pituitary response to the other releasing factors (corticotropin-releasing factor, growth hormone-releasing factor, and gonadotropin-releasing factor) is not altered, FGF increases both the sensitivity of the cells to thyrotropin-releasing factor and the amounts of prolactin and thyrotropin released. A minimum of 24 hr of preincubation with FGF is required to modify the pituitary response, and maximal effects were observed with 48 and 72 hr of preincubation. The effective doses of FGF are similar to those described for its mitogenic activity (i.e., 1-100 pM), but inhibition of cell growth with 5-fluorodeoxyuridine does not modify the effect of FGF on thyrotropin and prolactin release. These results suggest a novel paracrine, if not autocrine, role of pituitary FGF in the homeostatic mechanisms that regulate the secretion of prolactin and thyrotropin. They also suggest that the biological significance of the presence of FGF in various tissues may not be directly related to its in vitro mitogenic activity.

Acidic fibroblast growth factor (FGF) from bovine brain: amino-terminal sequence and comparison with basic FGF

Acidic fibroblast growth factor (FGF) from bovine brain has been isolated by a combination of salt precipitation, ion-exchange chromatography, heparin-Sepharose affinity chromatography and reverse phase h.p.l.c. The amino acid composition of the mitogen is indistinguishable from that of acidic FGF previously purified. The amino-terminal sequence of acidic FGF was established as Phe-Asn-Leu- Pro-Gly-Asn-Tyr-Lys-Pro-Lys-Leu-X-Tyr-X-Ser-Asn-Gly-X-Tyr-Phe-Leu-Arg-Il e-Leu-Pro-Asp-Gly. Acidic FGF is structurally different from basic FGF as judged by mol. wt., amino acid composition and sequence. In vitro biological comparison of the two growth factors indicates that acidic and basic FGFs possess the same intrinsic activities to stimulate the proliferation of aorta, vein or capillary endothelial cells and adrenal cortex cells, but acidic FGF is 30-100 times less potent, depending on the cell type.

Human brain fibroblast growth factor. Isolation and partial chemical characterization

Fibroblast growth factor (FGF) has been purified to homogeneity from human brain by a procedure involving salt precipitation, cation-exchange chromatography, Heparin-Sepharose affinity chromatography and reverse-phase HPLC. Isolation was monitored by radioimmunoassay and/or by testing column fractions for their capacity to stimulate the proliferation of vascular endothelial cells in vitro. The amino-terminal sequence of human brain FGF was determined as Pro-Ala-Leu-Pro-Glu-Asp-Gly-Gly-Ser-Gly-Ala-Phe-Pro-. This sequence is identical to that of the amino-terminal region of bovine FGF. Additional evidence, including amino acid composition, chromatographic retention behavior, and immunoreactivity suggest that the human and bovine mitogens are very similar in structure.

Immunoreactive fibroblast growth factor (FGF) in rat tissues: molecular weight forms and the effects of hypophysectomy

Rat tissues were extracted at neutral pH with dilute (0.15 M) ammonium sulfate and examined for presence of fibroblast growth factor immunoreactivity (ir-FGF). Ir-FGF was found in substantial amounts in all the tissues but higher amounts were found in liver and kidney. Gel filtration column chromatography showed the presence of three molecular weight peaks of ir-FGF, one associated with the void volume (the major form in kidney extract), another with an apparent molecular weight of 150-180,000 Da (the major form in serum) and a third one of 70,000 Da (the major form in the other tissues examined: pituitary, brain, liver, spleen and thymus). No immunoreactivity coeluted with authentic FGF purified from bovine pituitary glands, suggesting that FGF is present in neutral extracts in association with binding molecules and/or precursors. Hypophysectomy had no major effect on ir-FGF in the tissues, but increased its amount in serum. The results establish a wide distribution of FGF in several embryologically, morphologically and developmentally distinct tissues and indicate that the pituitary is not the major source of FGF immunoreactivity, although it can be involved in the regulation of plasma levels.

Effect of temocillin and moxalactam on platelet responsiveness and bleeding time in normal volunteers

The effects of temocillin and moxalactam on platelet responsiveness and bleeding time were examined in healthy male volunteers. In the first study, moxalactam (4 g intravenously every 12 h) was given to six subjects; template bleeding times were at least doubled in five subjects 12 to 14 h after 7 doses (P = 0.008) and in all six subjects 12 to 14 h after 13 doses (P = 0.004). ADP-induced primary aggregation was approximately halved after 7 (P = 0.026) and 13 doses (P = 0.008), and there was a markedly increased tendency toward disaggregation. Collagen-induced aggregation was also halved, but the effect only reached statistical significance after 13 doses (P = 0.008). There was essentially no effect on primary aggregation in response to the thromboxane receptor agonist U46619 or to platelet activating factor. Temocillin (4 g intravenously every 12 h) was given to eight subjects, three of whom had participated in the moxalactam study 8 weeks earlier. Temocillin had no significant effect on template bleeding time 12 to 14 h after 7 or 13 doses. However, in four subjects, the endpoint may have been less abrupt. There was no significant effect on ADP-induced primary aggregation or responsiveness to collagen. Even after 13 doses of temocillin, secondary aggregation in response to normal concentrations of ADP was demonstrable in the platelet-rich plasma of all eight subjects. Neither antibiotic had any effect on prothrombin times. Thus, with methodology that readily detected the effects of moxalactam on hemostasis, we were unable to demonstrate any unequivocal deleterious effects of temocillin at its maximum recommended dose. Temocillin may therefore be particularly useful for the treatment of many gram-negative infections in patients at increased risk of clinical bleeding.

Fibroblast growth factor in the human placenta

Fibroblast growth factor (FGF) has been purified 333,000-fold from human placenta by a combination of salt precipitation, cation-exchange chromatography, and Heparin-Sepharose affinity chromatography. Molecular weight (15-16 kDaltons), amino acid composition, bioactivity and immunological crossreactivity with bovine pituitary FGF indicate that the mitogens from the two species are closely related molecules.

Radioimmunoassay for fibroblast growth factor (FGF): release by the bovine anterior pituitary in vitro

A radioimmunoassay (RIA) was developed to measure fibroblast growth factor (FGF) using antiserum generated against a synthetic replicate of [Tyr10]FGF(1-10). The antisera, previously shown to be capable of inhibiting the biological action of FGF on bovine aortic arch endothelial cells in vitro, are highly specific for the amino-terminus of FGF. In the RIA, the antisera recognize the decapeptide antigen [Tyr10]FGF(1-10) and the intact mitogen on an equimolar basis and show less than 0.01% cross-reactivity with N-acetyl-[Tyr10]FGF(1-10). Bovine adenohypophysial cells maintained in primary monolayer culture release and ir-FGF which is indistinguishable from the intact mitogen in as much as it is retained on heparin-Sepharose affinity columns and shows a dose-dependent and parallel displacement in RIA. The release of ir-FGF by the bovine adenohypophysis can be increased with forskolin (10(-5) M) or KCl (50 mM). Preincubation of pituitary cells with 17 beta-estradiol has no measurable effects on basal ir-FGF, but increases the release after KCl treatment 2-3-fold. These results show that ir-FGF can be released by the bovine adenohypophysis in vitro and lend credence to the hypothesis that FGF plays a physiological role in the homeostatic mechanisms regulating mesoderm-derived cell growth.

GRF is a highly potent activator of adenylate cyclase in the normal human, bovine and rat pituitary: interaction with somatostatin

The effect of GRF adenylate cyclase activation was studied in normal human, bovine and rat pituitary tissues. Human GRF (hGRF) activates adenylate cyclase in normal human pituitary membrane preparations in a concentration dependent manner (ED5 0 = 10(-11) M). In bovine pituitary cells hGRF stimulates GH secretion into the medium (ED5 0 = 7 X 10(-12) M) and activates adenylate cyclase (ED5 0 = 10(-11) M). In normal rat pituitary cells in monolayer culture, rat GRF (rGRF) stimulates adenylate cyclase (ED5 0 = 3 X 10(-11) M). In normal human pituitary membrane preparations and in normal rat pituitary cells in culture, somatostatin inhibits GRF-stimulated adenylate cyclase in a non-competitive manner, while it does not affect basal (i.e. non-stimulated) adenylate cyclase levels. VIP, a peptide which is structurally homologous to hGRF and rGRF is a weak GRF-agonist and activates adenylate cyclase in human and rat pituitary preparations at concentrations greater than 10 nM.

The effects of testosterone and estrogen on the pituitary growth hormone response to growth hormone-releasing factor

The effects of testosterone and estrogen on the pituitary growth hormone response to hypothalamic growth hormone-releasing factor (GRF) were evaluated in vivo using male and female rats and in vitro using a pituitary cell monolayer culture system. In vivo the increase in plasma growth hormone (GH) concentration in response to a 500 ng/kg dose of GRF was similar in gonadectomized male and female rats. Pretreatment of intact and gonadectomized male rats with testosterone caused significant enhancement of the pituitary GH response to GRF, whereas pretreatment of gonadectomized female rats with 17 beta-estradiol did not alter the response. The GH response to GRF was not different between prepubertal (i.e., 30-day-old) male and female rats. However, following puberty (i.e., by 60 days of age), the response in male rats was significantly greater than that observed in female rats. The in vitro preincubation of anterior pituitary cells with either testosterone or 17 beta-estradiol did not cause any shift in the dose-response curve between GRF and GH. These results demonstrated that androgens play an active role in modulating the pituitary response to GRF in vivo.

Immunoreactive fibroblast growth factor in cells of peritoneal exudate suggests its identity with macrophage-derived growth factor

Peritoneal exudate cells were collected from thioglycollate stimulated mice, extracted an examined for the presence of immunoreactive and bioactive fibroblast growth factor (FGF). The crude extract stimulated in a dose dependent fashion the proliferation of vascular endothelial cells derived from the bovine aortic arch. The extract also showed a parallel and dose-dependent inhibition of binding in a highly specific radioimmunoassay for FGF. The immunoreactive FGF (ir-FGF) contained in the extract was retained on a heparin-sepharose affinity column as is characteristic of pituitary FGF. Reverse-phase HPLC of the macrophage-derived material reveals one biologically active form of FGF which coelutes with the major form of immunoreactivity. The results demonstrate the presence of FGF in these cells and suggest that at least one of the hitherto unidentified mitotic activities in these extracts is due to a mitogen indistinguishable from FGF.

Temocillin in the treatment of chest infections

In our study, 16 patients with acute infection complicating severe respiratory disease were treated with temocillin 2g or 3g daily for 5 to 10 days. In 10 patients, a recognised respiratory pathogen, either Haemophilus influenzae (temocillin-sensitive) or Streptococcus pneumoniae (temocillin-resistant), was isolated from sputum before the start of treatment. 13 patients improved clinically but 5 subsequently relapsed. Two patients failed to respond, and 1 died of respiratory failure. There was no clearcut relationship between the clinical progress and sensitivity of the isolated pathogen to temocillin, and there were no adverse effects associated with the administration of temocillin.

Somatostatin-28 [1-12]-like peptides

The search for a peptide corresponding to the NH2-terminus of somatostatin-28 (SS-28) in tissues has led to the isolation and characterization of somatostatin-28[1-12] from pancreas and hypothalamus. Somatostatin-28[1-12]-like immunoreactivity [SS-28 [1-12]-LI] is widely distributed throughout the central nervous system and the digestive system of rodents and primates, reaching levels comparable to those of somatostatin-14 (SS-14). Antibodies directed against the C-terminal end of the dodecapeptide are more specific and constitute excellent markers for the "prosomatostatin" system in mammalian tissues. In rat brain, SS-28[1-12]-LI material is highly concentrated in nerve fibres and terminals, especially in the median eminence, layer I of neocortex, the outer molecular layer of the dentate gyrus and the striatum. Additionally, immunoreactivity is observed in large multipolar or occasionally pyramidal-like neurons of the neocortex. SS-28[1-12] is secreted from hypothalamus and amygdala by a calcium dependent mechanism. No biological role is presently known for the dodecapeptide. Two other peptides of Mr = 8000 (8 K) and Mr = 5000 (5 K) which contain SS-28[1-12] at their carboxy-termini are present in acid extracts from rat pancreas, brain and spinal cord. These two peptides were isolated from an acid extract of rat brains using ion-exchange chromatography, gel permeation chromatography and reverse-phase HPLC. Results from amino acid analysis and partial sequencing were compared to the sequence of the cDNA encoding rat pre-prosomatostatin (prepro-SS) and revealed that the 8 K peptide is a 76 amino acid molecule corresponding to prepro-SS[25-100] and that the 5K peptide, which contains 44 amino acids, corresponds to prepro-SS [57-100]. The 5 K peptide was generated after cleavage of a Leu-Leu bond at position 56-57 of prepro-SS. The four most predominant peptides of the "prosomatostatin system" presently characterized are: SS-14, SS-28[1-12], SS-28 and prepro-SS[25-100]. Studies on pooled perfusates from rat hypothalamic tissue show that prepro-SS[25-100] is released with SS-28[1-12] in vitro and accounts for 22% of the total SS-28[1-12]-like immunoreactive material released during depolarization. The 5 K peptide is apparently not secreted. The presence of prepro-SS[25-100] in brain implies that, first, prosomatostatin can serve as an immediate precursor for SS-14 without going through SS-28 as an intermediate step and second, other peptides could conceivably be derived from the cryptic portion of the precursor.

Lung tissue penetration of temocillin

Eight patients about to have the whole or part of a lung resected were given a 2g bolus dose of temocillin. A series of serum samples and a piece of peripheral lung tissue were collected and assayed for temocillin concentration. 30 minutes after drug administration, the mean serum and tissue concentrations were 172 mg/L and 45 mg/kg respectively.

Inhibition of aldosterone production in the adrenal glomerulosa by atrial natriuretic factor

Several forms of the polypeptide atrial natriuretic factor (ANF) have been isolated recently from rat and human atria and identified; they are probably associated with the secretory granules of atrial tissue. The potent ability of ANFs to increase urine sodium content is mediated by their direct action on the kidney. We report here the high intrinsic activity of a synthetic replicate of one form of this molecule, ANF(8-33)(ref. 7), to inhibit directly basal aldosterone secretion and its ability to antagonize the stimulatory effects of adrenocorticotropin (ACTH) and angiotensin II (AN-II) on the secretion of aldosterone by rat adrenoglomerulosa cells in vitro. Our results suggest that ANF is of clinical importance in the management of aldosterone-dependent hypertension by modifying the adrenocortical response to endogenous ACTH and AN-II.