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A Baird

Publications and source records attributed to A Baird.

At least 73 records · Page 4Linked to original sources
PubMed1995

A comprehensive analysis of the distribution of FGF-2 and FGFR1 in the rat brain.

We have examined the cellular distribution of both FGF-2 and FGFR1 immunoreactivity and their mRNAs throughout the normal adult rat brain in order to reconcile numerous disparate findings in the published literature. The results confirm a widespread distribution of FGF-2 and FGFR1 in the rat brain, and different regions express distinct patterns of FGF-2 and FGFR1 mRNA and protein: neuronal and non-neuronal cells show different subcellular distributions that vary according to the area where they are located. The intensity of the staining and hybridization also varies according to the loci examined and the cell type involved. Astrocytes contain the highest levels of FGF-2 and FGFR1 mRNAs, and characteristically, possess high levels of immunoreactive FGF-2 within the nucleus. Amongst non-neuronal cells, oligodendrocytes do not synthesize or contain significant levels of FGF-2 immunoreactivity however, they do express FGFR1 mRNA. In these cells, immunoreactive FGFR1 is mainly associated with the myelin sheaths of neuronal fibers. In ventricular systems, ependymal cells synthesize and contain immunoreactive FGFR1. In contrast, only cells lining the lateral wall of the IIIrd ventricle express FGF-2 mRNA. Subependymal cells contain high levels of both FGF-2 and FGFR1 immunoreactivity. Neurons express low levels of FGF-2 mRNA and immunoreactive FGF-2 is localized predominantly to the perikaryon. However, selected populations of neurons, such as CA2 field of the hippocampus, show high levels of FGF-2 mRNA, in which the nucleus is strongly immunopositive. Similarly, high levels of FGFR1 mRNA are localized to select populations of neurons (e.g. amygdala). FGFR1 immunoreactivity is mainly associated with myelinated fiber tracts (e.g. striatum), and some neurons show immunoreactivity in the perikaryon (e.g. hippocampus), the nucleus (e.g. mesencephalic trigeminal nucleus), or in axonal projections (e.g. hypothalamus). Remarkably, in many of the areas studied, FGF-2 and FGFR1 mRNA and/or their translated protein do not co-localize in neurons (e.g. neo-cortices) or even in the same regions of the brain (e.g. substantia nigra). In other instances, mRNAs for both FGF-2 and FGFR1 colocalize (e.g. supraoptic nucleus). The brain, in contrast to peripheral tissues, contains high levels of FGF-2 and actively expresses its gene under normal physiological conditions. The highly specific anatomical distribution of immunoreactive FGF-2 in neuronal and non-neuronal brain cells, supports the notion that it plays a multifunctional role in the CNS under normal physiology. By correlating the localization and the synthesis of FGF-2 and one of its high affinity receptors, FGFR1, in the CNS, it should be possible to obtain a better understanding of the roles of FGF-2 in normal and pathological conditions.

Animals↗
PubMed1995

Expression of acidic FGF mRNA in rat auditory brainstem during postnatal maturation.

In situ hybridization was used to investigate the mRNA distribution of acidic and basic fibroblast growth factor (aFGF and bFGF) in the auditory brainstem of neonatal and adult rats. bFGF mRNA was not detected at any age. In adult rats, aFGF mRNA was strongly expressed in the principal neurons of the anteroventral and posteroventral cochlear nuclei, but not in the octopus cells. In the dorsal cochlear nucleus, aFGF mRNA was seen only in scattered smaller vertical cells. aFGF was strongly expressed in the nucleus of the trapezoid body and in all periolivary cell groups, but not in the medial and lateral olivary nuclei. No expression was observed in the lemniscal nuclei or in the central nucleus of the inferior colliculus, but large neurons in the external zone of the colliculus were labeled. Developmentally, low levels of aFGF expression appeared in the cochlear nuclei and olivary nuclei between P0 and P6. This expression increased rapidly during the onset of hearing, between P10 and P14, and reached adult level by P14-P17. Labeling in collicular neurons appeared slightly later. The results suggest that the appearance of strong aFGF mRNA expression is related to the onset of function.

Aging↗
PubMed1995

A fibroblast growth factor binding protein in human cerebral spinal fluid.

A soluble protein which binds basic fibroblast growth factor (FGF-2) has been detected in cerebral spinal fluid from normal individuals and patients with Alzheimer's disease and Parkinson's disease. This 70-85 kDa protein is recognized by an antibody to the extracellular domain of the high affinity FGF receptor and is not detected by an antibody to the intracellular domain of the FGF receptor, suggesting that it consists of a truncated portion of the extracellular domain of the high affinity FGF receptor. This FGF-BP appears to be identical to the two IgG-like loop form of FGFR-1 identified and purified from human and bovine blood. The possibility that this FGF-BP may play a role in transporting, sequestering, or even delivering the FGFs to target cells in the CNS is discussed.

Alzheimer Disease↗
PubMed1995

Central action of basic fibroblast growth factor on ingestive behaviour in mice.

Intracerebroventricular (ICV) infusion of basic fibroblast growth factor (FGF-2) at 50 ng/h for 5 days in male BALB/c mice suppressed the daily intakes of water and food (n = 4). Intakes were reduced on the second day, and were suppressed until the second day after stopping the infusion. The same infusion for 4 days had little effect on the high intakes of 0.3 M NaCl solution and water induced by prolonged ICV infusion of angiotensin II, or the daily food intake in these experiments (n = 7). However, the same infusion for 3-4 days reduced the increased intake of NaCl solution in Na-depleted mice (n = 8), reduced the increased water intake of water-restricted mice (n = 6 or n = 7), and reduced daily food intake in both experiments. Ventricular enlargement was noted in mice at the end of these experiments but, for reasons advanced, did not appear to account for the responses. The results indicate that FGF-2 may have an inhibitory role in these ingestive behaviours.

Angiotensin II↗
PubMed1995

Basic fibroblast growth factor increases dopaminergic graft survival and function in a rat model of Parkinson's disease.

The clinical use of fetal neural grafts as an intracerebral source of dopamine for patients with Parkinson's disease has met with limited success. Since basic fibroblast growth factor (bFGF) enhances the survival and growth of dopaminergic neurons in vitro, we explored whether cells genetically modified to produce bFGF would improve the functional efficacy of dopaminergic neurons implanted into rats with experimental Parkinson's disease. Results show that bFGF-producing cells grafted together with fetal dopamine neurons have potent growth-promoting effects on the implanted neurons in vivo. Moreover, rats implanted with such co-grafts display the most pronounced behavioural improvements post-grafting. These findings not only provide insight into the function of bFGF in situ, but also suggest an approach for enhancing the survival and function of dopamine neurons grafted into the damaged brain.

Animals↗
PubMed1995

Expression of biologically active basic fibroblast growth factor by genetically modified rat primary skin fibroblasts.

Basic fibroblast growth factor (FGF-2) is normally expressed as a cell-associated protein, and accordingly it is not clear how it exerts its action on target cells in vivo. It has been proposed that cells release, by death or other mechanisms, small amounts of FGF-2 that then acts in an autocrine manner. To address the question of whether it is necessary that FGF-2 remain cell associated or needs to be secreted from cells to have biological activity, we expressed the 18-kDa form of FGF-2 in primary fibroblasts as a cell-associated (FGF-2-B) or as a secreted (FGF-2-S) protein. FGF-2 protein is detected in cell lysates and membrane fractions of both cell types, whereas it is present in significant amounts only in the conditioned medium of FGF-2-S cells. No FGF-2 is detected in control (untransfected) cells. FGF-2-S cells also grow faster than the control of FGF-2-B cells. Yet, when evaluated for their ability to promote the survival of embryonic hippocampal neurons in vitro, both the cell types are active, establishing the activity of the transgene product. We conclude that FGF-2 is active when engineered to be expressed as a cell-associated form or secreted from cells.

Animals↗
PubMed1995

High affinity immunoreactive FGF receptors in the extracellular matrix of vascular endothelial cells--implications for the modulation of FGF-2.

We recently characterized three FGF-binding proteins (FGF-BPs) which are soluble forms of the extracellular domains of the high affinity FGF receptors (Hanneken, A. M., W. Ying, N. Ling, and A. Baird. Proc. Natl. Acad. Sci. USA. 1994. 91:9170-9174). These proteins circulate in blood and have been proposed to modulate the biological activity of the FGF family of proteins. Immunohistochemical studies now demonstrate that these soluble, truncated FGF receptors are also present in the basement membranes of retinal vascular endothelial cells. These immunoreactive proteins can be detected with antibodies raised to the extracellular domain of FGFR-1 but not with antibodies raised to either the juxtamembrane domain or the cytoplasmic domain of FGFR-1. Western blotting of human retinal extracts with the antibody raised to the extracellular domain of FGFR-1 detects specific, low molecular mass proteins at 85 kD and 55 kD, corresponding in size to the FGF-BPs, which are not detected with antibodies against the cytoplasmic domain of the receptor. The interaction of this receptor with the extracellular matrix is not dependent on the presence of FGF-2. Immunoreactive receptors are still detected in vascular basement membranes after the removal of FGF-2 with heparitinase. In addition, the recombinant extracellular domain of FGFR-1 continues to bind to corneal endothelial cell matrix after endogenous FGF-2 has been removed with 2 M NaCl. Acid treatment, which has been shown to disrupt protein interactions with the extracellular matrix, leads to a significant reduction in the presence of the matrix form of the FGF receptor. This loss can be restored with exogenous incubations of the recombinant extracellular domain of FGFR-1. This report is the first demonstration that a truncated form of a high affinity growth factor receptor can be localized to the extracellular matrix. These findings add to the list of binding proteins associated with the extracellular matrix (IGFBP-5) and suggest a potentially new regulatory mechanism for controlling the biological availability of FGF, and other peptide growth factors, in the extracellular matrix.

Amino Acid Sequence↗
PubMed1995

Adenosine diphosphate ribosylation of fibroblast growth factor-2.

Basic fibroblast growth factor (FGF-2) is posttranslationally modified by the enzymatic transfer of ADP-ribose from nicotinamide adenine dinucleotide (NAD). When sonicated nuclei of adrenal capillary endothelial or SK-Hep1 cells are incubated with [32P]NAD, FGF-2 is rapidly ADP-ribosylated in a dose- and time-dependent fashion. Proteins structurally related to FGF-2 (FGF-6 and -7) are readily modified, suggesting that they share a common substrate motif. Yet, FGF-1, the most structurally homologous member of the FGF family, is a poor substrate. The reaction is also specific; interleukin-1 alpha, transforming growth factor-alpha, nerve growth factor, insulin-like growth factor-I, and granulocyte macrophage-colony stimulating factor are not substrates for ribosylation. Because the ADP ribosylation of FGF-2 is acid resistant but base and hydroxylamine sensitive, the linkage appears to be mediated through arginine. Most importantly, however, we also establish that endogenous FGF-2 is a substrate for ribosylation. As such, an immunoreactive ADP-ribosylated FGF-2 is detected in extracts of SK-Hep1 nuclei when they are incubated with [32P]NAD. Taken together, these findings suggest that the role played by ADP ribosylation in signal transduction, DNA repair, the control of the cell cycle, and cell differentiation may involve its ability to target molecules such as FGF-2.

Adenocarcinoma↗
PubMed1995

Soluble forms of the high-affinity fibroblast growth factor receptor in human vitreous fluid.

PURPOSE: Fibroblast growth factor-binding proteins (FGF-BPs) have been identified recently in blood and other biologic fluids and have been shown to be identical to a truncated form of the high-affinity cell surface FGF receptor. The authors examined the hypothesis that FGF-BPs also are present in human vitreous fluid. METHODS: Vitreous fluid obtained from 12 patients was incubated overnight with heparin-Sepharose, FGF-2 heparin-Sepharose, and wheat germ agglutinin (WGA)-Sepharose, a lectin known to bind to high-affinity FGF receptors. The precipitated proteins were characterized by immunoblotting using two FGF receptor antibodies raised to either the extracellular domain of FGFR-1 or the intracellular domain of FGFR-1. RESULTS: A 70- to 85-kd FGF-BP was detected in the vitreous in each of the 12 eyes examined. A 55-kd FGF-BP was detected in six of the samples. Both the 70-to 85-kDa and the 55-kDa proteins were precipitated by FGF-2 heparin-Sepharose but not by heparin-Sepharose alone, suggesting that the interaction was dependent on the presence of FGF-2. The proteins bound avidly to WGA-Sepharose. Western blot analysis revealed that the proteins were recognized by an antibody raised to the extracellular domain of the high-affinity FGF receptor but not by an antibody raised to the intracellular domain of the FGF receptor, indicating they are likely to be truncated portions of the extracellular domain of the high-affinity FGF receptor. CONCLUSIONS: Vitreous fluid contains 70- to 85-kd and 55-kd FGF-BPs that have biochemical and immunologic characteristics similar to the extracellular domain of the high-affinity FGF receptor. These naturally occurring FGF-BPs may sequester free FGF in the vitreous cavity and may modulate the biologic activity of FGF in vitreoretinal diseases.

Aged↗
PubMed1994

Storage, metabolism, and processing of 125I-fibroblast growth factor-2 after intracerebral injection.

Basic fibroblast growth factor (FGF-2) is a potent trophic agent for both neuronal and non-neuronal cells of the mammalian CNS. It can enhance survival and neurite outgrowth of a variety of neuronal types in vitro and in vivo, and recently has been shown to stimulate neuroblast proliferation in culture. To determine the most effective means of introducing FGF-2 into the brain, and to further our understanding of the behavior of exogenous FGF-2 following intracerebral injection, we examined the diffusion and degradation of 125I-FGF-2 following intraventricular or intraparenchymal injection. SDS-PAGE and autoradiography show that when radiolabelled FGF-2 is injected into the parenchyma of the rat brain, it remains at the site of injection where it is detectable for several days. During this time, it is slowly metabolized to 2 specific heparin-binding metabolic fragments that are virtually identical to the ones described for its metabolism by neurons and astrocytes in vitro. Microscopic examination and autoradiography of these tissue sections show that within these areas, FGF-2 diffuses throughout the site of injection. Initially, it migrates along adjacent fiber tracts, binds to specific cells and to basement membranes of the microvasculature, but later on it remains associated to basement membranes and non-neuronal cells. Based on its slow clearance and slow rate metabolic degradation, this FGF-2 is presumed to be in a sequestered form and to have limited activity. In contrast, the intraventricular injection of 125I-FGF leads to a rapid clearance, with some binding to ependymal cells lining the ventricles and little translocation into the parenchyma.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Identification of soluble forms of the fibroblast growth factor receptor in blood.

We have purified three acidic (FGF-1) and basic (FGF-2) fibroblast growth factor binding proteins (FGF-BP1, FGF-BP2, and FGF-BP3) from human plasma and calf serum and demonstrate the presence of these circulating FGF-BPs in blood. Each are truncated forms of the high-affinity FGF receptor (FGFR-1). FGF-BP1 and FGF-BP2 have estimated molecular masses of 70-85 kDa and 55-60 kDa, respectively, and are detected by using 125I-labeled FGF-2 ligand blotting. Immunoblotting with four distinct antibodies to FGFR-1 reveals that FGF-BP1 and FGF-BP2 are immunologically and biochemically related to the extracellular domain of FGFR-1. Reverse-phase HPLC chromatography resolves FGF-BP2 into two proteins with estimated molecular masses of 55 kDa and 60 kDa. Protein sequencing of the amino terminus of FGF-BP2 and FGF-BP3 reveals identity with the extracellular domain of the two-IgG-loop form of human FGFR-1. The FGF-BPs do not require heparin to bind FGF-2 on affinity columns, but heparin does enhance their recovery from blood. These FGF-BPs may play an important physiological role in regulating the biological activity of FGF and the other members of the FGF family of growth factors.

Amino Acid Sequence↗
PubMed1994

Anti-B16-F10 melanoma activity of a basic fibroblast growth factor-saporin mitotoxin.

BACKGROUND: The authors attached basic fibroblast growth factor (FGF-2), a growth factor for numerous tumors and normal cell types, to saporin (SAP), a ribosome-inactivating protein isolated from the plant Saponaria officinalis. The conjugate (FGF-SAP) then was tested for antitumor activity using B16-F10 melanoma cells. This rapidly growing murine melanoma cell line has been used classically as a model to screen antitumor agents. METHODS: B16-F10 cells in culture were used for in vitro experiments or introduced into C57BL/6 mice to demonstrate the in vivo antitumor activities of FGF-SAP. RESULTS: FGF-SAP was found to be an extremely effective cytocidal agent in vitro with an ED50 of 30-60 pM. The effects were specific for FGF-2 receptors, as shown by the ability of FGF-2 to block FGF-SAP action. In the in vivo models, FGF-SAP was found to increase survival time, inhibit tumor growth, and decrease metastases. CONCLUSIONS: The authors conclude that this mitotoxin has potent in vitro and in vivo effects on B16-F10 cells, supporting the hypothesis that ligand-mediated cytotoxicity can control tumor growth.

Animals↗
PubMed1994

Expression and activities of a recombinant basic fibroblast growth factor-saporin fusion protein.

A fusion protein containing the full-length sequences of the mitogen, basic fibroblast growth factor (FGF-2), and the ribosome-inactivating protein, saporin (SAP), has been expressed in E. coli. As expected, it binds with high affinity to heparin-Sepharose like FGF-2 and can displace the binding of radiolabeled FGF-2 to its high affinity receptor. In contrast, the fusion protein only has much lower ribosome-inactivating activity than free saporin, although full ribosome-inactivating protein activity can be generated by proteolytic removal of the FGF-2 moiety. Cytotoxicity experiments with B16-F10 mouse melanoma cells establish that the fusion protein is active as a chemical conjugate against these intact cells. Presumably these cells have the ability to activate the SAP component of the fusion protein through an intra-cellular metabolism of the fusion protein. Because we also show the fusion protein has tumor growth inhibition properties and antimetastatic activity in in vivo models of melanoma, the findings support the hypothesis that FGF-based ligand-mediated cytotoxicity can serve to target cytotoxic agents in vivo.

Animals↗
PubMed1994

Effects of transforming growth factor beta 1 on scar production in the injured central nervous system of the rat.

In the central nervous system (CNS), nerve regeneration after traumatic injury fails. The formation of a dense fibrous scar is thought to restrict in part the growth of axonal projections, providing one of the many reasons that complete lesions of neural pathways in the adult mammalian CNS are rarely followed by significant functional recovery. In order to determine which mechanisms mediate scar formation in the CNS and to investigate whether they can be modulated in vivo, we have attempted to define the potential role of trophic factors. Our previous studies have shown the focal elevation of transforming growth factor beta 1 (TGF beta 1) expression in lesioned CNS tissue. In the studies described here, we demonstrate that TGF beta 1 participates in the scarring response in the rat brain. First, the elevated protein levels of TGF beta 1 are localized to specific populations of injury-responsive cells in the traumatized CNS. Furthermore, the injection of TGF beta 1 into the brains of injured rats causes a dramatic increase in the scarring response. Conversely, when neutralizing TGF beta 1 antibodies are administered, the deposition of fibrous scar tissue and the formation of a limiting glial membrane that borders the lesion is significantly attenuated, thus establishing a role for the endogenous growth factor in regulation of the non-glial component of the scar. In implicating TGF beta 1 in the scarring response in the CNS, the potential use for TGF beta 1 antagonists as inhibitors of scar formation in the injured mammalian CNS is self-evident.

Animals↗
PubMed1994

Potential mechanisms regulating the extracellular activities of basic fibroblast growth factor (FGF-2).

Basic fibroblast growth factor (FGF-2) is nearly ubiquitous in its distribution, leading numerous investigators to propose that there must exist highly specific mechanisms to regulate its bioavailability. Moreover, in each of the tissues where it can be localized, numerous cells are its potential target. The identification of these mechanisms could serve as an important step in developing novel strategies to inhibit FGF action. It could be possible to block such FGF-dependent activities as angiogenesis, tumor growth, reproduction, and selected diseases of cell proliferation. Over the course of the past several years, we have attempted to describe some of the processes that might regulate a target cell's ability to activate FGF-2 in its local milieu.

Animals↗
PubMed1994

In vivo and in vitro effects of androgen on fibroblast growth factor-2 concentrations in the human prostate.

Prostatic growth is primarily regulated by dihydrotestosterone (DHT). Recent studies have demonstrated that a large number of growth factors are present in the human benign prostatic hyperplasia (BPH) prostate, including epidermal growth factor (EGF), transforming growth factor-alpha (TGF-alpha), transforming growth factor beta (TGF-beta), insulin-like growth factor (IGF), and basic fibroblast growth factor (bFGF) (FGF-2). DHT may mediate its mitogenic effects in the prostate by regulating growth factors. To test this hypothesis, we have utilized a histoculture androgen sensitivity assay (HASA) in which 3H-thymidine incorporation is measured in aliquots of BPH tissue in histoculture with either added DHT or hydroxyflutamide (HF). The resulting DHT/HF ratio is an expression of the androgen sensitivity of the tissue. In this study, we have compared the DHT/HF ratio for 3H-thymidine incorporation to the DHT/HF ratio for FGF-2 measured in the histocultured prostates. The DHT/HF ratio for the HASA studies of 3H-thymidine incorporation averaged 2.68 compared to the DHT/HF ratio for FGF-2 in the same specimens of 1.01. These values were significantly different, therefore indicating no relationship between DHT stimulation and FGF-2 levels. In addition, FGF-2 levels were measured in human BPH prostates from patients medically castrated with megesterol acetate and estradiol 17-beta prior to surgery. These values were not significantly different, and therefore do not suggest any effect of DHT on the concentration of prostatic FGF-2. Although these studies did not show any effect of DHT on the regulation of prostatic FGF-2, they do indicate that the HASA assay is feasible and appropriate to use in the study of relationships between DHT and various growth factors.

Androgen Antagonists↗
PubMed1994

Fibroblasts genetically modified to produce nerve growth factor induce robust neuritic ingrowth after grafting to the spinal cord.

The influences of neurotrophic factors on adult mammalian spinal cords are incompletely understood. In the present experiment, we utilized somatic gene transfer to examine the effects of nerve growth factor (NGF) on the unlesioned spinal cords of adult Fischer rats. Fischer 344 rat primary fibroblasts were genetically modified in vitro to produce and secrete NGF, then grafted to spinal cords at the T7 level. Grafts survived in vivo for periods of up to 1 year, and induced an extremely robust ingrowth of spinal neurites. Control and basic fibroblast growth factor-producing grafts did not promote extensive neurite growth. Neurites penetrating the NGF grafts were of sensory origin, since they labeled immunocytochemically for calcitonin gene-related peptide but not markers of other neuronal transmitter phenotypes. Electron microscopy revealed that neurites within NGF-secreting grafts were enveloped in glial cell processes and that axons frequently became myelinated. These results indicate that (i) genetically modified cell grafts are a useful model for studying trophic factor effects in the adult mammalian spinal cord, (ii) sensory neurites maintain robust NGF responsiveness into adulthood, and (iii) sprouting neurites can follow glial channels and become myelinated in the adult spinal cord. Grafts of fibroblasts genetically modified to secrete trophic factors merit study as potential tools for promoting regeneration after spinal cord injury.

Animals↗