Biomedical subjects

M Goldfarb

Publications and source records attributed to M Goldfarb.

At least 19 recordsLinked to original sources

PubMed2001

Signaling by fibroblast growth factors: the inside story.

Polypeptide growth factors bind to the extracellular domains of cell surface receptors, triggering activation of receptor-intrinsic or receptor-associated protein kinases. Although this central thesis is widely accepted, one family of proteins, the fibroblast growth factors (FGFs), have for more than a decade attracted a research "counterculture" looking for direct FGF actions inside cells. Goldfarb discusses how the search for alternative signaling pathways is moving mainstream with the help of two recent publications reporting specific intracellular targets for FGF and FGF-like proteins.

Animals↗

PubMed2001

Fibroblast growth factor homologous factors are intracellular signaling proteins.

Fibroblast growth factors (FGFs) mediate cell growth, differentiation, migration, and morphogenesis by binding to the extracellular domain of cell surface receptors, triggering receptor tyrosine phosphorylation and signal transduction [1-5]. FGF homologous factors (FHFs) were discovered within vertebrate DNA sequence databases by virtue of their sequence similarity to FGFs [3, 6, 7], but the mechanism of FHF action has not been reported. We show here that FHF-1 is associated with the MAP kinase (MAPK) scaffold protein Islet-Brain-2 (IB2) [8] in the brain and in specific cell lines. FHF/IB2 interaction is highly specific, as FHFs do not bind to the related scaffold protein IB1(JIP-1b) [9, 10], nor can FGF-1 bind to IB2. We further show that FHFs enable IB2 to recruit a specific MAPK in transfected cells, and our data suggest that the scaffolds IB1 and IB2 have different MAPK specificities. Hence, FHFs are intracellular components of a tissue-specific protein kinase signaling module.

Animals↗

PubMed2001

Multiple effector domains within SNT1 coordinate ERK activation and neuronal differentiation of PC12 cells.

Differentiation of neuronal precursor cells in response to neurotrophic differentiation factors is accompanied by the activation of membrane-anchored SNT signaling adaptor proteins. Two classes of differentiation factors, the neurotrophins and fibroblast growth factors, induce rapid tyrosine phosphorylation of SNT1(FRS2alpha), which in turn enables SNT1 to recruit Shp2 tyrosine phosphatase and Grb2 adaptor protein in complex with the Ras GDP/GTP exchange factor Sos. To determine effector functions of SNT that promote neuronal differentiation of PC12 pheochromocytoma cells, we engineered a chimeric protein, SNT1(IRS)CX, bearing the effector region of SNT1 and the insulin receptor recognition domains of IRS2. Insulin promoted tyrosine phosphorylation of SNT1(IRS)CX in transfected PC12 cells accompanied by sustained activation of ERK1/2 mitogen-activated protein kinases and neuronal differentiation. The SNT1(IRS)CX-mediated response was dependent on endogenous Ras, MEK, and Shp2 activities. Mutagenesis of SNT1(IRS)CX identified three classes of effector motifs within SNT critical for both sustained ERK activation and neuronal differentiation: 1) four phosphotyrosine motifs that mediate recruitment of Grb2, 2) two phosphotyrosine motifs that mediate recruitment of Shp2, and 3) a C-terminal motif that functions by helping to recruit Sos. We discuss possible mechanisms by which three functionally distinct SNT effector motifs collaborate to promote a downstream biochemical and biological response.

3T3 Cells↗

PubMed2001

Analysis of antibody to milk proteins in HIV positive/negative sera using two-dimensional electrophoresis, western blot and immunoassay.

Homology between the 120 envelope glycoprotein of HIV-1 virus and alpha-lactalbumin (a milk protein) stimulated interest in analysis of antibody in HIV-1 positive plasma to cow's milk. Western blots of a two-dimensional (2-D) separation of milk were assayed with nine HIV-1 positive plasmas and nine control sera. The control sera from reference labs represented various disease problems. All nine HIV-1 positive plasma had antibody to between two and five milk proteins. All nine HIV-1 positive plasma had antibody to albumin and immunoglobulin (IgG); in addition, seven reacted with butyrophilin, five with alpha-lactalbumin, six with casein. Four of the control sera had no antibody to milk proteins; three had minor reactivity to casein and two, one diagnosed as an IgM Lyme positive, one diagnosed with Helicobacter pylori detected three and four milk proteins. None of the control sera had antibody to albumin or alpha-lactalbumin. Bovine and human albumin have almost identical sequence, and antibody generated to bovine serum albumin could react with human serum albumin. To look at this, three of the HIV-1 positive plasmas were assayed with 2-D Western blots of human milk and did have reactivity with albumin and IgG. Also, the protein butyrophilin is highly immunogenic and has significant homology with human neural and cellular proteins. Whether these antibodies can be causing allergy or autoimmune disease is speculative, but they indicate an immune system which is highly activated.

Cross Reactions↗

PubMed2001

Transient urethral obstruction predisposes to ascending pyelonephritis and tubulo-interstitial disease: studies in rats.

Chronic tubulo-interstitial disease, an important cause of end-stage renal disease, often results from the combined effects of a disturbed urinary outflow tract and urinary tract infection. Acute unilateral ureteral obstruction in rats rapidly induces foci of medullary necrosis, confined to the region of the papilla and fornices. This injury may provide a nidus for bacterial invasion and may invoke reactive and regenerative changes, ultimately leading to chronic pyelonephritis and tubulo-interstitial nephropathy. To explore this possibility, adult rats underwent renal morphological evaluation 2-7 days following transient 24-h unilateral ureteral obstruction. In some experiments the bladder was inoculated with bacteria (10(8)-10(9) cfu/ml Escherichia coli in 0.5 ml) after release of ureteral obstruction, with subsequent cultures obtained from the pelvis of both kidneys and from the urinary bladder. Morphologic evaluation of perfusion-fixed kidneys, 2-7 days after the release of 24-h ureteral obstruction disclosed papillary necrosis, urothelial proliferation, marked inner-stripe interstitial expansion, and fibrosis and proximal tubular (S3) dilatation. The lateral (perihilar region) was predominantly affected, with lesions spreading from the fornices. There was some progression of interstitial fibrosis during the postobstructive time course or following more prolonged ureteral obstruction. By contrast, infection hardly contributed to the tubulointerstitial changes. In rats subjected to infection, cultures were positive in all 15 postobstructive kidneys, as opposed to five contralateral kidneys (P < 0.0001). Viable counts from the postobstructive kidney were also higher than those from the contralateral side (79,000 +/- 12,000 vs 2900 +/- 1600 cfu/ml, mean +/- SEM, P < 0.0001), and were comparable to those obtained from the bladder (77,000 +/- 13,000 cfu/ml). We conclude that transient ureteral obstruction predisposes to ascending pyelonephritis and to tubulointerstitial disease. This vulnerability may relate to altered urodynamics and medullary tissue destruction.

Animals↗

PubMed2001

SNT-1/FRS2alpha physically interacts with Laloo and mediates mesoderm induction by fibroblast growth factor.

Members of the fibroblast growth factor (FGF) ligand family play a critical role in mesoderm formation in the frog Xenopus laevis. While many components of the signaling cascade triggered by FGF receptor activation have been identified, links between these intracellular factors and the receptor itself have been difficult to establish. We report here the characterization of Xenopus SNT-1 (FRS2alpha), a scaffolding protein previously identified as a mediator of FGF activity in other biological contexts. SNT-1 is widely expressed during early Xenopus development, consistent with a role for this protein in mesoderm formation. Ectopic SNT-1 induces mesoderm in Xenopus ectodermal explants, synergizes with low levels of FGF, and is blocked by inhibition of Ras activity, suggesting that SNT-1 functions to transmit signals from the FGF receptor during mesoderm formation. Furthermore, dominant-inhibitory SNT-1 mutants inhibit mesoderm induction by FGF, suggesting that SNT-1 is required for this process. Expression of dominant-negative SNT-1 in intact embryos blocks mesoderm formation and dramatically disrupts trunk and tail development, indicating a requirement for SNT-1, or a related factor inhibited by the mutant construct, during axis formation in vivo. Finally, we demonstrate that SNT-1 physically associates with the Src-like kinase Laloo, and that SNT-1 activity is required for mesoderm induction by Laloo, suggesting that SNT-1 and Laloo function as components of a signaling complex during mesoderm formation in the vertebrate.

Adaptor Proteins, Signal Transducing↗

PubMed2001

Compensated heart failure predisposes to outer medullary tubular injury: studies in rats.

BACKGROUND: Heart failure (HF) is considered a putative factor predisposing to acute renal failure (ARF). Since outer medullary hypoxic injury may play an important role in the pathogenesis of acute tubular necrosis, we explored the impact of experimental HF on the propensity to develop ARF with hypoxic medullary injury following the inhibition of prostaglandin and nitric oxide synthesis. METHODS: Compensated, high-output HF was induced in Sprague-Dawley rats by aorto-caval fistula. At the eighth to ninth postoperative day, the rats were injected with indomethacin and N(omega) nitro-L-arginine methyl ester (L-NAME; ARF protocol) and were sacrificed 24 hours later for morphologic evaluation. RESULTS: Kidney function comparably declined in HF-ARF rats and in control sham operated animals (CTR-ARF). Nevertheless, outer medullary hypoxic damage with medullary thick ascending limb (mTAL) necrosis occurred almost exclusively in the HF-ARF group (11 +/- 4% vs. 0.2 +/- 0.2% of tubules in CTR-ARF, P < 0.03). In a third group of HF animals subjected to vehicles only (HF-Nil), kidney function was preserved and renal morphology remained intact. Papillary-tip necrosis was consistently found in all animals subjected to indomethacin and L-NAME, irrespective of preconditioning. Morphometric evaluation disclosed that HF was not associated with mTAL hypertrophy. CONCLUSIONS: Incipient HF predisposes to hypoxic outer medullary injury, probably reflecting the impact of regional vasoconstrictive stimuli rather than tubular hypertrophy when protective local vasodilating mechanisms are hampered. The presence and extent of outer medullary hypoxic damage cannot be predicted from the functional derangement, which in the experimental settings may also represent prerenal azotemia or papillary damage.

Acute Kidney Injury↗

PubMed2001

Renal effects of nabumetone, a COX-2 antagonist: impairment of function in isolated perfused rat kidneys contrasts with preserved renal function in vivo.

The constitutive cyclooxygenase (COX)-1 enzyme has been considered the physiologically important isoform for prostaglandin synthesis in the normal kidney. It has, therefore, been suggested that selective inhibitors of the 'inducible' isoform (COX-2) may be free from renal adverse effects. We studied the renal effects of the predominantly COX-2 antagonist nabumetone in isolated perfused kidneys. As compared with controls, kidneys removed after in vivo administration of oral nabumetone (15 mg/kg) disclosed altered renal function with reduced glomerular filtration rate, filtration fraction, and urine volume and enhanced hypoxic outer medullary tubular damage. By contrast, renal function and morphology were not affected in vivo by nabumetone or its active metabolite 6-methoxy-2-naphthylacetic acid. The latter agent (10-20 mg/kg i.v.) did not significantly alter renal microcirculation, as opposed to a selective substantial reduction in medullary blood flow noted with the nonselective COX inhibitor indomethacin (5 mg/kg i.v.). In a rat model of acute renal failure, induced by concomitant administration of radiocontrast, nitric oxide synthase, and COX inhibitors, the decline in kidney function and the extent of hypoxic medullary damage with oral nabumetone (80 mg/kg) were comparable to a control group, and significantly less than those induced by indomethacin. In rats subjected to daily oral nabumetone for 3 consecutive weeks, renal function and morphology were preserved as well. Both nabumetone and 6-methoxy-2-naphthylacetic acid reduced renal parenchymal prostaglandin E2 to the same extent as indomethacin. It is concluded that while nabumetone adversely affects renal function and may intensify hypoxic medullary damage ex vivo, rat kidneys are not affected by this agent in vivo, both in acute and chronic studies. COX selectivity may not explain the renal safety of nabumetone.

Acute Kidney Injury↗

PubMed1999

Initiation of mammalian liver development from endoderm by fibroblast growth factors.

The signaling molecules that elicit embryonic induction of the liver from the mammalian gut endoderm or induction of other gut-derived organs are unknown. Close proximity of cardiac mesoderm, which expresses fibroblast growth factors (FGFs) 1, 2, and 8, causes the foregut endoderm to develop into the liver. Treatment of isolated foregut endoderm from mouse embryos with FGF1 or FGF2, but not FGF8, was sufficient to replace cardiac mesoderm as an inducer of the liver gene expression program, the latter being the first step of hepatogenesis. The hepatogenic response was restricted to endoderm tissue, which selectively coexpresses FGF receptors 1 and 4. Further studies with FGFs and their specific inhibitors showed that FGF8 contributes to the morphogenetic outgrowth of the hepatic endoderm. Thus, different FGF signals appear to initiate distinct phases of liver development during mammalian organogenesis.

Animals↗

PubMed1999

Genomic organization and embryonic expression of the mouse fibroblast growth factor 9 gene.

Fibroblast growth factor 9 (FGF9), originally cloned as glial-activating factor from human glioma cells, is expressed in adult rat brain and kidney. Here we report the chromosomal localization, genomic organization, and embryonic expression pattern of the mouse Fgf9 gene. Fgf9 maps to chromosome 14 near the Ctla6 locus. The gene spans more than 34 kb and contains three exons and two introns. Translation initiation occurs in exon 1, and translation termination occurs in exon 3. Fgf9 RNA was detected during mouse embryogenesis in several tissues in which Fgf gene expression has not been previously described, including intermediate mesoderm of late-stage gastrulation, ventricular myocardium, lung pleura, skeletal myoblasts in the early limb bud, spinal cord motor neurons, olfactory bulb, and gut lumenal epithelium. Fgf9 is coexpressed with other Fgf genes in some skeletal myoblasts, in limb apical ectoderm, in craniofacial ectoderm, and in the retina, inner ear, and tooth bud. Dev Dyn 1999;216:72-88.

Amino Acid Sequence↗

PubMed1999

Tissue oxygenation modifies nitric oxide bioavailability.

OBJECTIVE: Because changes in blood oxygenation acutely alter vascular tone, we explored a possible modulation of nitric oxide-induced vasodilation (nitrovasodilation) by oxygen. METHODS: We studied the effects of manipulation of tissue oxygenation on renal parenchymal nitric oxide (NO) with a selective NO electrode placed in the well-oxygenated renal cortex or in the physiologically hypoxemic outer medulla. RESULTS: In the cortex, as expected, NO signals fell in response to the NO synthase (NOS) inhibitor L-NAME. By contrast, in the outer medulla, NO signals paradoxically rose following NOS inhibition, known to intensify local hypoxia. Other manipulations that intensify outer medullary hypoxia (such as indomethacin or radiologic contrast media) increased local NO readings, while measures known to ameliorate outer medullary hypoxia (furosemide, L-arginine, hypotension) reduced regional NO readings. CONCLUSIONS: Oxygen appears to modulate NO bioavailability, in particular, in tissues with low ambient pO2, perhaps through enhanced binding to oxygenated hemoglobin. It is proposed that this phenomenon may participate in physiological microvascular regulation, with hypoxemia enhancing NO concentration, while hyperoxemia resulting in accelerated NO removal.

Animals↗

PubMed1998

Novel recognition motif on fibroblast growth factor receptor mediates direct association and activation of SNT adapter proteins.

Fibroblast growth factors (FGFs) stimulate tyrosine phosphorylation of a membrane-anchored adapter protein, FRS2/SNT-1, promoting its association with Shp-2 tyrosine phosphatase and upstream activators of Ras. Using the yeast two-hybrid protein-protein interaction assay, we show that FRS2/SNT-1 and a newly isolated SNT-2 protein directly bind to FGF receptor-1 (FGFR-1). A juxtamembrane segment of FGFR-1 and the phosphotyrosine-binding domain of SNTs are both necessary and sufficient for interaction in yeast and in vitro, and FGFR-mediated SNT tyrosine phosphorylation in vivo requires these segments of receptor and SNT. Our findings establish SNTs as direct protein links between FGFR-1 and multiple downstream pathways. The SNT binding motif of FGFR-1 is distinct from previously described phosphotyrosine-binding domain recognition motifs, lacking both tyrosine and asparagine residues.

3T3 Cells↗

PubMed1998

Quality indicators using hospital discharge data: state and national applications.

BACKGROUND: Demand for information about the quality of health care has escalated. Yet many organizations lack well-specified quality measures, statistical expertise, or the requisite data to produce such information. The Healthcare Cost and Utilization Project Quality Indicators (HCUP QIs) represent one approach to measuring health care quality using readily available data on hospital inpatients. METHODS: The HCUP QIs, developed in 1994, address clinical performance rather than other dimensions of quality such as satisfaction or efficiency. The 33 indicators produce rates that represent measures of outcomes (mortality and complications), utilization, and access. In lieu of complex multivariate techniques, two methods were used: (1) restrictions in defining patient subgroups to isolate homogeneous at-risk populations and (2) standardization when populations are diverse. Stratified analyses are recommended when patient or hospital factors are believed to influence the outcome. A simple method for making statistical comparisons to national rates was developed. The HCUP QI software, available in both mainframe and microcomputer applications, have enabled organizations to use their own data to produce comparative statistics and examine trends over time. Results summarized at the individual hospital or aggregate level are being used to stimulate continuous quality improvement initiatives. CONCLUSIONS: The HCUP QIs offer a low-cost alternative for organizations that have access to administrative data. Current users include hospital associations, state health departments, statewide data organizations, and individual hospitals. Although the HCUP QIs are intended to serve as indicators, not definitive measures, of quality, they were designed to highlight quality concerns and to target areas for more intensive study.

Benchmarking↗

PubMed1998

Computerized depression screening and awareness.

The DEPRESSION Awareness, Recognition and Treatment (D/ART) program under the sponsorship of the National Institutes of Health has made consistent efforts to help educate many communities around the nation about depression. One important aspect of this effort includes offering free screening for depression to the general public. Since new technology often promotes curiosity and interest, a computerized depression screening and awareness program was created to use at fairs and other local events. Individuals who participated completed a computerized version of the Center for Epidemiological Studies Depressed Mood Scale (CES-D) and then received a one page printout that described the common symptoms of depression, a score indicative of their level of depressed mood, a brief explanation of the score, and a telephone number where additional information could be obtained. This paper details the construction of the computerized version of the CES-D including an evaluation of psychometric properties and consumer satisfaction with the program.

Adult↗

PubMed1997

Amino acid residues which distinguish the mitogenic potentials of two FGF receptors.

Fibroblast growth factors mediate cellular responses by interacting with a family of related receptor tyrosine kinases (FGFRs). We have previously shown that FGFR-1, but not of FGFR-4, ectopically expressed in BaF3 lymphoid cells allows for proliferation in response to FGFs, and that the intracellular signaling halves of these two receptors distinguish their mitogenic potentials (Wang et al., 1994). In order to map the residues which functionally distinguish these receptors, a panel of chimeric receptors whose cytodomains bear different contributions from FGFR-1 and FGFR-4 were constructed and characterized. The behavior of these chimeras implicate amino acids from both the kinase insert and kinase domains in receptor-mediated proliferation. Specifically, two tyrosine residues present in the short kinase insert domain of FGFR-1 and absent from FGFR-4 are a necessary, but not sufficient, component of a fully mitogenic receptor, suggesting that tyrosine phosphorylation in the kinase insert promotes a mitogenic signaling pathway. A strongly mitogenic receptor also requires one or two FGFR-1-specific residues from either of two regions within the kinase domain. One of these regions is within the kinase domain's activation loop, where FGFR-1, but not FGFR-4, bears a key aspartate residue. The mitogenic potentials of FGFR-1, FGFR-4, and the chimeric receptors strongly correlates with the magnitude of ligand-induced receptor autophosphorylation in BaF3 cells. We discuss mechanisms by which these few key amino acid differences may determine the levels of ligand-induced FGF receptor autophosphorylation and mitogenic potency.

Amino Acid Sequence↗

PubMed1997

Chromosomal mapping of two novel human FGF genes, FGF11 and FGF12.

The fibroblast growth factor (FGF) family comprises to date 12 members, which are involved in various physiological processes throughout embryogenesis and adult life. Two novel members of the family have been identified recently (FGF11 and FGF12). Using in situ hybridization on metaphasic chromosomes, we have been able to assign FGF11 to band p12-p13 of human chromosome 17 and FGF12 to band q28 of human chromosome 3.

Base Sequence↗

PubMed1997

Of worms and men: an evolutionary perspective on the fibroblast growth factor (FGF) and FGF receptor families.

FGFs (fibroblast growth factors) play major roles in a number of developmental processes. Recent studies of several human disorders, and concurrent analysis of gene knock-out and properties of the corresponding recombinant proteins have shown that FGFs and their receptors are prominently involved in the development of the skeletal system in mammals. We have compared the sequences of the nine known mammalian FGFs, FGFs from other vertebrates, and three additional sequences that we extracted from existing databases: two human FGF sequences that we tentatively designated FGF10 and FGF11, and an FGF sequence from Caenorhabditis elegans. Similarly, we have compared the sequences of the four FGF receptor paralogs found in chordates with four non-chordate FGF receptors, including one recently identified in C. elegans. The comparison of FGF and FGF receptor sequences in vertebrates and nonvertebrates shows that the FGF and FGF receptor families have evolved through phases of gene duplications, one of which may have coincided with the emergence of vertebrates, in relation with their new system of body scaffold.

Amino Acid Sequence↗

PubMed1997

Murine FGF-12 and FGF-13: expression in embryonic nervous system, connective tissue and heart.

The molecular cloning of cDNAs encoding murine fibroblast growth factor-13 (FGF-13/FHF-2) and three isoforms of murine FGF-12 (FHF-1) is described. Like their highly conserved human counterparts, murine FGF-12 and FGF-13 are part of a distinct subfamily of FGF-like proteins characterized by a greater degree of amino acid sequence cross-homology and by conserved N-terminal domains which do not include secretion signal sequences. In addition to their expression in several adult tissues, both of these FGF genes are prominently and regionally expressed in midgestation mouse embryos, as revealed by in situ hybridization. Fgf12 and fgf13. RNAs were detected in developing central nervous system in cells outside the proliferating ependymal layer, and fgf13 RNA was also found throughout the peripheral nervous system. Fgf12 is expressed in developing soft connective tissue of the limb skeleton and in presumptive connective tissue linking vertebrae and ribs. Both FGF genes are also expressed in the myocardium of the heart, with fgf12 RNA found only in the atrial chamber and fgf13 RNA detected in both atrium and ventricle. On the basis of their novel structure and patterns of expression, FGF-12 and FGF-13 are anticipated to perform embryonic functions distinct from other known FGF molecules.

Adult↗