scispace - formally typeset
Search or ask a question

Showing papers by "University of Alabama at Birmingham published in 1994"


Journal ArticleDOI
TL;DR: In this paper, the influence of NO on membrane lipid peroxidation induced by O2-, H2O2, and OH derived from xanthine oxidase (XO) and by ONOO- was assessed by formation of thiobarbituric acid-reactive products and by liquid chromatography-mass spectrometry.

1,371 citations


Journal ArticleDOI
TL;DR: There is sufficient evidence of a protective effect to warrant continued investigation of the role of soyfoods in cancer prevention, and in vitro, animal, and epidemiological data are examined.
Abstract: International variations in cancer rates have been attributed, at least in part, to differences in dietary intake. Recently, it has been suggested that consumption of soyfoods may contribute to the relatively low rates of breast, colon, and prostate cancers in countries such as China and Japan. Soybeans contain a number of anticarcinogens, and a recent National Cancer Institute workshop recommended that the role of soyfoods in cancer prevention be investigated. In this review, the hypothesis that soy intake reduces cancer risk is considered by examining relevant in vitro, animal, and epidemiological data. Soybeans are a unique dietary source of the isoflavone genistein, which possesses weak estrogenic activity and has been shown to act in animal models as an antiestrogen. Genistein is also a specific inhibitor of protein tyrosine kinases; it also inhibits DNA topoisomerases and other critical enzymes involved in signal transduction. In vitro, genistein suppresses the growth of a wide range of can...

1,369 citations


Journal ArticleDOI
25 Mar 1994-Science
TL;DR: Levels of soluble Fas were elevated in patients with systemic lupus erythematosus, and mice injected with soluble Fas displayed autoimmune features.
Abstract: Fas is an apoptosis-signaling receptor molecule on the surface of a number of cell types. Molecular cloning and nucleotide sequence analysis revealed a human Fas messenger RNA variant capable of encoding a soluble Fas molecule lacking the transmembrane domain because of the deletion of an exon encoding this region. The expression of soluble Fas was confirmed by flow cytometry and immunocytochemical analysis. Supernatants from cells transfected with the variant messenger RNA blocked apoptosis induced by the antibody to Fas. Levels of soluble Fas were elevated in patients with systemic lupus erythematosus, and mice injected with soluble Fas displayed autoimmune features.

1,142 citations


Journal ArticleDOI
TL;DR: The presence of nitrotyrosine indicates that oxidants derived from nitric oxide such as peroxynitrite are generated in human atherosclerosis and may be involved in its pathogenesis.
Abstract: Oxidation of lipoproteins is important for the initiation and propagation of the atherosclerotic lesion and may involve secondary oxidants derived from nitric oxide. Nitric oxide (NO) reacts at near diffusion limited rates with superoxide (O2-.) to form the strong oxidant, peroxynitrite (ONOO-). Nitration on the ortho position of tyrosine is a major product of peroxynitrite attack on proteins. Nitrotyrosine was detected in atherosclerotic lesions of formalin-fixed human coronary arteries with polyclonal and monoclonal antibodies. Binding was pronounced in and around foamy macrophages within the atheroma deposits. Nitration was also observed in early subintimal fatty streaks. Antibody binding was completely blocked by co-incubation with 10mM nitrotyrosine, but not by equivalent concentrations of aminotyrosine or phosphotyrosine. The presence of nitrotyrosine indicates that oxidants derived from nitric oxide such as peroxynitrite are generated in human atherosclerosis and may be involved in its pathogenesis.

1,141 citations


Book ChapterDOI
TL;DR: This chapter presents that essentially all of the nitric oxide produced by rat alveolar macrophages activated with phorbol ester is converted to peroxynitrite, a strong oxidant that can be stored for weeks in alkaline solution or even entrapped in solid forms.
Abstract: Publisher Summary Nitric oxide (.NO) is an important and largely unrecognized mediator of oxygen radical injury because it contains an unpaired electron that readily combines with many free radicals. Endothelium and neurons produce nitric oxide as an intercellular messenger, which has important roles in vasoregulation and synaptic plasticity. Nitric oxide reacts rapidly with superoxide to form the strong oxidant, peroxynitrite anion (ONOO - ). Activated macrophages and neutrophils can produce nitric oxide and superoxide at similar rates. This chapter presents that essentially all of the nitric oxide produced by rat alveolar macrophages activated with phorbol ester is converted to peroxynitrite. Peroxynitrite is not a free radical because the unpaired electrons on nitric oxide and superoxide have combined to form a new N–O bond in peroxynitrite. Peroxynitrite anion can be stored for weeks in alkaline solution or even entrapped in solid forms. During its decomposition at physiological pH, peroxynitrite can produce some of the strongest oxidants known in a biological system, initiating reactions characteristic of hydroxyl radical, nitronium ion, and nitrogen dioxide. The unusual stability of peroxynitrite as an anion contributes to its toxicity by allowing it to diffuse far from its site of formation while being selectively reactive with cellular targets.

980 citations


Journal ArticleDOI
TL;DR: A multicenter randomized trial that compared amphotericin B with fluconazole as treatment for candidemia, with the most common diagnoses being renal failure, nonhematologic cancer, and gastrointestinal disease.
Abstract: Background Amphotericin B has long been the standard treatment for candidemia, but its use is complicated by its toxicity. More recently, fluconazole, a water-soluble triazole with activity against candida species and little toxicity, has become available. We conducted a multicenter randomized trial that compared amphotericin B with fluconazole as treatment for candidemia. Methods To be eligible, patients had to have a positive blood culture for candida species, a neutrophil count ≥ 500 per cubic millimeter, and no major immunodeficiency. Patients were randomly assigned to receive either amphotericin B (0.5 to 0.6 mg per kilogram of body weight per day) or fluconazole (400 mg per day), each continued for at least 14 days after the last positive blood culture. Outcomes were assessed by a group of investigators blinded to treatment assignment. Results Of the 237 patients enrolled, 206 met all entry criteria. The most common diagnoses were renal failure, nonhematologic cancer, and gastrointestinal disease. T...

969 citations


Journal ArticleDOI
TL;DR: The recommendations for monitoring and selection of patients for liver biopsy identify patients at potential risk for CSLD, and thus significantly reduce the number or patients who would be exposed to this procedure.
Abstract: Methotrexate (MTX) has become an important drug in the treatment of rheumatoid arthritis (RA). The American College of Rheumatology convened a committee to assess the risks of development of clinically significant liver disease (CSLD) during MTX treatment, to evaluate the risk and role of surveillance liver biopsies, and to provide recommendations about monitoring patients for liver toxicity. The committee recommends obtaining liver blood tests (alanine aminotransferase [ALT], aspartate aminotransferase [AST], alkaline phosphatase, albumin, bilirubin), hepatitis B and C serologic studies, and other standard tests including complete blood cell count and serum creatinine tests prior to starting treatment with MTX. A pretreatment liver biopsy should be considered only for patients with a history of prior excessive alcohol consumption, persistently abnormal baseline AST values, or chronic hepatitis B or C infection. At intervals of every 4-8 weeks the AST, ALT, and albumin levels should be monitored. Routine surveillance liver biopsies are not recommended for RA patients receiving traditional doses of MTX. However, a biopsy should be performed if a patient develops persistent abnormalities on liver blood tests. These are defined as elevations (above the upper limit of laboratory normal) in the AST in 5 of 9 determinations within a given 12-month interval (6 of 12 if tests are performed monthly) or a decrease in serum albumin below the normal range. The recommendations for monitoring and selection of patients for liver biopsy identify patients at potential risk for CSLD, and thus significantly reduce the number or patients who would be exposed to this procedure. Close monitoring is essential to reduce the risk of unrecognized serious liver disease. These recommendations should be revised as necessary to reflect new and compelling information.

790 citations


Journal ArticleDOI
TL;DR: It is concluded that dihydrorhodamine is a sensitive and efficient trap for peroxynitrite and may serve as a probe for each other's production and also as an important mediator of free radical-induced cellular injury.

703 citations


Journal ArticleDOI
TL;DR: The results suggest that the reaction of O2- with .NO is involved in the development of atherosclerotic disease by yielding a potent mediator of lipoprotein oxidation, as well as by limiting .NO stimulation of vascular smooth muscle guanylate cyclase activity.
Abstract: The role of reactive oxygen species in the vascular pathology associated with atherosclerosis was examined by testing the hypothesis that impaired vascular reactivity results from the reaction of nitric oxide (.NO) with superoxide (O2-), yielding the oxidant peroxynitrite (ONOO-). Contractility studies were performed on femoral arteries from rabbits fed a cholesterol-supplemented diet. Cholesterol feeding shifted the EC50 for acetylcholine (ACh)-induced relaxation and impaired the maximal response to ACh. We used pH-sensitive liposomes to deliver CuZn superoxide dismutase (SOD; superoxide:superoxide oxidoreductase, EC 1.15.1.1) to critical sites of .NO reaction with O2-. Intravenously injected liposomes (3000 units of SOD per ml) augmented ACh-induced relaxation in the cholesterol-fed group to a greater extent than in controls. Quantitative immunocytochemistry demonstrated enhanced distribution of SOD in both endothelial and vascular smooth muscle cells as well as in the extracellular matrix. SOD activity in vessel homogenates of liposome-treated rabbits was also increased. Incubation of beta very low density lipoprotein with ONOO- resulted in the rapid formation of conjugated dienes and thiobarbituric acid-reactive substances. Our results suggest that the reaction of O2- with .NO is involved in the development of atherosclerotic disease by yielding a potent mediator of lipoprotein oxidation, as well as by limiting .NO stimulation of vascular smooth muscle guanylate cyclase activity.

701 citations


Journal ArticleDOI
TL;DR: Edwin Blalock discusses how these shared ligands and receptors are used as a common chemical language for communication within and between the immune and neuroendocrine systems, suggesting an immunoregulatory role for the brain and a sensory function for the immune system.

685 citations


Journal ArticleDOI
TL;DR: Acute DSS-induced colitis does not require the presence of T cells or B cells because it occurred in C.B17 severe combined immunodeficient mice that lack these cells, and its induction may result from a toxicity of DSS for colonic epithelial cells.

Journal ArticleDOI
11 Aug 1994-Nature
TL;DR: Major oligoclonal expansions of these CD8+ T lymphocytes may represent an important component of the primary immune response to viral infections and may help to clarify both the immunopathogenic and the protective mechanisms of HIV infection.
Abstract: A SIGNIFICANT proportion (up to 70%) of individuals experience an acute clinical syndrome of varying severity associated with primary infection with the human immunodeficiency virus (HIV). We report here studies on six individuals who showed an acute HIV syndrome which generally resolved within four weeks, concomitant with a dramatic downregulation of viraemia. To characterize the T-cell-mediated primary immune response to HIV, we used combined semiquantitative polymerase chain reaction assay and cytofluorometry to analyse the T-cell antigen receptor repertoire in sequential peripheral blood mononuclear cells from the patients. We found major oligoclonal expansions in a restricted set of variable-domain beta-chain (V beta) families. Cells expressing the expanded V beta s predominantly expressed the CD8 T-cell differentiation antigen and mediated HIV-specific cytotoxicity. Major oligoclonal expansions of these CD8+ T lymphocytes may represent an important component of the primary immune response to viral infections and may help to clarify both the immunopathogenic and the protective mechanisms of HIV infection.

Journal ArticleDOI
TL;DR: Data suggest that toxic levels of peroxynitrite may be formed in the lungs of patients with acute lung injury, and nitrotyrosine formation in rat lung sections incubated in vitro with peroxyrosine, but not nitric oxide or reactive oxygen species.
Abstract: Activated alveolar macrophages and epithelial type II cells release both nitric oxide and superoxide which react at near diffusion-limited rate (6.7 x 10(9) M-1s-1) to form peroxynitrite, a potent oxidant capable of damaging the alveolar epithelium and pulmonary surfactant. Peroxynitrite, but not nitric oxide or superoxide, readily nitrates phenolic rings including tyrosine. We quantified the presence of nitrotyrosine in the lungs of patients with the adult respiratory distress syndrome (ARDS) and in the lungs of rats exposed to hyperoxia (100% O2 for 60 h) using quantitative immunofluorescence. Fresh frozen or paraffin-embedded lung sections were incubated with a polyclonal antibody to nitrotyrosine, followed by goat anti-rabbit IgG coupled to rhodamine. Sections from patients with ARDS (n = 5), or from rats exposed to hyperoxia (n = 4), exhibited a twofold increase of specific binding over controls. This binding was blocked by the addition of an excess amount of nitrotyrosine and was absent when the nitrotyrosine antibody was replaced with nonimmune IgG. In additional experiments we demonstrated nitrotyrosine formation in rat lung sections incubated in vitro with peroxynitrite, but not nitric oxide or reactive oxygen species. These data suggest that toxic levels of peroxynitrite may be formed in the lungs of patients with acute lung injury.

Journal ArticleDOI
TL;DR: Ketoconazole, the first oral azole to be introduced, is less well tolerated than either fluconazole or itraconazole and is associated with more clinically important toxic effects, including hepatitis and inhibition of steroid hormone synthesis.
Abstract: The oral azole drugs--ketoconazole, fluconazole, and itraconazole--represent a major advance in systemic antifungal therapy. Among the three, fluconazole has the most attractive pharmacologic profile, including the capacity to produce high concentrations of active drug in cerebrospinal fluid and urine. Ketoconazole, the first oral azole to be introduced, is less well tolerated than either fluconazole or itraconazole and is associated with more clinically important toxic effects, including hepatitis and inhibition of steroid hormone synthesis. However, ketoconazole is less expensive than fluconazole and itraconazole--an especially important consideration for patients receiving long-term therapy. All three drugs are effective alternatives to amphotericin B and flucytosine as therapy for selected systemic mycoses. Ketoconazole and itraconazole are effective in patients with the chronic, indolent forms of the endemic mycoses, including blastomycosis, coccidioidomycosis, and histoplasmosis; itraconazole is also effective in patients with sporotrichosis. Fluconazole is useful in the common forms of fungal meningitis--namely, coccidioidal and cryptococcal meningitis. In addition, fluconazole is effective for selected patients with serious candida syndromes such as candidemia, and itraconazole is the most effective of the azoles for the treatment of aspergillosis.

Journal ArticleDOI
TL;DR: A fuzzy neural network will be a layered, feedforward, neural net that has fuzzy signals and/or fuzzy weights.

Journal ArticleDOI
18 Feb 1994-Science
TL;DR: Results suggest that NO production and its extracellular movement may be links in the pathway from NMDA receptor activation to changes in chemical signaling in surrounding synaptic terminals in the cerebral cortex.
Abstract: L-Glutamate and norepinephrine are examples of a major excitatory neurotransmitter and a neuromodulator in the cerebral cortex, respectively. Little is known of how chemical signaling between the anatomically distinct chemical pathways occurs. Specific activation of the N-methyl-D-aspartate (NMDA) class of glutamate receptor in synaptosomal preparations from guinea pig cerebral cortex caused release of both of these chemicals, and this release was blocked by agents that inhibit nitric oxide (NO) production or remove NO from the extracellular space. Furthermore, neurotransmitter release correlated with cortical NO production after NMDA receptor stimulation. These results suggest that NO production and its extracellular movement may be links in the pathway from NMDA receptor activation to changes in chemical signaling in surrounding synaptic terminals in the cerebral cortex.

Journal ArticleDOI
TL;DR: It is suggested that cGMP-dependent activation of the cAMP kinase may be responsible in part at least for the NO-dependent inhibition of proliferation of subcultured rat aortic SMC.
Abstract: Recent studies indicate that nitric oxide (NO) and guanosine 3',5'-cyclic monophosphate (cGMP) may inhibit the proliferation of vascular smooth muscle cells (SMC) in vitro. The purpose of this stud...


Journal ArticleDOI
TL;DR: Acid reflux is the primary factor in the development of Barrett's esophagus and bile reflux parallels acid reflux and, at best, may have a synergistic role, while aggressive acid suppression with omeprazole markedly decreases both.

Journal ArticleDOI
TL;DR: Five attributes of health care delivery that define patients' perceptions of quality and satisfaction are identified and managerial implications for diagnosing quality concerns of patients are discussed.
Abstract: Patient-based determinants of quality and satisfaction play an important role in choosing a health care provider. This study identifies five attributes of health care delivery that define patients' perceptions of quality and satisfaction. Managerial implications for diagnosing quality concerns of patients are discussed.

Journal ArticleDOI
TL;DR: Analysis of antibody sequences in CLL indicates that CLL cells use a repertoire characteristic of mature cells, and suggests that antigen may play a role in the pathogenesis of this disease.

Journal ArticleDOI
TL;DR: A tuned transmission line resonator developed in theory and in practical design for the clinical NMR volume coil application at 4.1 tesla has been demonstrated to be a function of the electromagnetic properties of the load itself and uncompromised high field advantages of signal‐to‐noise and spatial resolution.
Abstract: A tuned transmission line resonator has been developed in theory and in practical design for the clinical NMR volume coil application at 4.1 tesla. The distributed circuit transmission line resonator was designed for high frequency, large conductive volume applications where conventional lumped element coil designs perform less efficiently. The resonator design has made use of a resonant coaxial cavity, which could be variably tuned to the Larmor frequency of interest by tunable transmission line elements. Large head- and body-sized volumes, high efficiencies, and broad tuning ranges have been shown to be characteristic of the transmission line resonator to frequencies of 500 MHz. The B1 homogeneity of the resonator has been demonstrated to be a function of the electromagnetic properties of the load itself. By numerically solving Maxwell's equations for the fully time-dependent B1 field, coil homogeneity was predicted with finite-element models of anatomic structure, and inhomogeneities corrected for. A how-to exposition of coil design and construction has been included. Simple methods of quadrature driving and double tuning the transmission line resonator have also been presented. Human head images obtained with a tuned transmission line resonator at 175 MHz have clearly demonstrated uncompromised high field advantages of signal-to-noise and spatial resolution.

Journal ArticleDOI
TL;DR: Preliminary data is reported suggesting that shaping with verbal feedback further enhances the motor recovery and may be termed learned nonuse.
Abstract: A new approach to the rehabilitation of movement, based primarily on the principles of operant conditioning, was derived from research with deafferented monkeys. The analysis suggests that a certain proportion of excess motor disability after certain types of injury involves a learned suppression of movement and may be termed learned nonuse. Learned nonuse can be overcome by changing the contingencies of reinforcement so that they strongly favor use of an affected upper extremity in the chronic postinjury situation. The techniques employed here involved 2 weeks of restricting movement of the opposite (unaffected) extremity and training of the affected limb. Initial work with humans has been with chronic stroke patients for whom the approach has yielded large improvements in motor ability and functional independence. We report here preliminary data suggesting that shaping with verbal feedback further enhances the motor recovery.

Journal ArticleDOI
TL;DR: Data indicate that matrix metalloproteinases are expressed in cell-type, tissue, and reproductive cycle-specific patterns, consistent with regulation by steroid hormones, and with specific roles in the complex tissue growth and remodeling processes occurring in the endometrium during the reproductive cycle.
Abstract: Matrix metalloproteinases are a highly regulated family of enzymes, that together can degrade most components of the extracellular matrix. These proteins are active in normal and pathological processes involving tissue remodeling; however, their sites of synthesis and specific roles are poorly understood. Using in situ hybridization, we determined cellular distributions of matrix metalloproteinases and tissue inhibitor of metalloproteinase-1, an inhibitor of matrix metalloproteinases, in endometrium during the reproductive cycle. The mRNAs for all the metalloproteinases were detected in menstrual endometrium, but with different tissue distributions. The mRNA for matrilysin was localized to epithelium, while the others were detected in stromal cells. Only the transcripts for the 72-kD gelatinase and tissue inhibitor of metalloproteinases-1 were detected throughout the cycle. Transcripts for stromelysin-2 and the 92-kD gelatinase were only detected in late secretory and menstrual endometrium, while those for matrilysin, the 72-kD gelatinase, and stromelysin-3 were also consistently detected in proliferative endometrium. These data indicate that matrix metalloproteinases are expressed in cell-type, tissue, and reproductive cycle-specific patterns, consistent with regulation by steroid hormones, and with specific roles in the complex tissue growth and remodeling processes occurring in the endometrium during the reproductive cycle.

Journal ArticleDOI
TL;DR: The results indicate that the genetic and biological diversity of HIV-2 is far greater than previously appreciated and suggest that there may be subtype-specific differences in virus biology.
Abstract: The virulence properties of human immunodeficiency virus type 2 (HIV-2) are known to vary significantly and to range from relative attenuation in certain individuals to high-level pathogenicity in others. These differences in clinical manifestations may, at least in part, be determined by genetic differences among infecting virus strains. Evaluation of the full spectrum of HIV-2 genetic diversity is thus a necessary first step towards understanding its molecular epidemiology, natural history of infection, and biological diversity. In this study, we have used nested PCR techniques to amplify viral sequences from the DNA of uncultured peripheral blood mononuclear cells from 12 patients with HIV-2 seroreactivity. Sequence analysis of four nonoverlapping genomic regions allowed a comprehensive analysis of HIV-2 phylogeny. The results revealed (i) the existence of five distinct and roughly equidistant evolutionary lineages of HIV-2 which, by analogy with HIV-1, have been termed sequence subtypes A to E; (ii) evidence for a mosaic HIV-2 genome, indicating that coinfection with genetically divergent strains and recombination can occur in HIV-2-infected individuals; and (iii) evidence supporting the conclusion that some of the HIV-2 subtypes may have arisen from independent introductions of genetically diverse sooty mangabey viruses into the human population. Importantly, only a subset of HIV-2 strains replicated in culture: all subtype A viruses grew to high titers, but attempts to isolate representatives of subtypes C, D, and E, as well as the majority of subtype B viruses, remained unsuccessful. Infection with all five viral subtypes was detectable by commercially available serological (Western immunoblot) assays, despite intersubtype sequence differences of up to 25% in the gag, pol, and env regions. These results indicate that the genetic and biological diversity of HIV-2 is far greater than previously appreciated and suggest that there may be subtype-specific differences in virus biology. Systematic natural history studies are needed to determine whether this heterogeneity has clinical relevance and whether the various HIV-2 subtypes differ in their in vivo pathogenicity.

Journal ArticleDOI
TL;DR: Reduction in plasma Hcy by interventions to increase plasma folate concentration may decrease CAD risk, and no difference in the geometric mean of vitamin B-12 concentration was found between patients and control subjects.

Journal ArticleDOI
21 Oct 1994-Cell
TL;DR: The results identify Sec9 as the yeast cognate of SNAP-25 and suggest that SNARE complexes acting at specific stages of vesicular transport serve as the ultimate targets of regulation by members of the Sec4/Ypt1/Rab family of GTPases.

Journal ArticleDOI
TL;DR: It is reported that syndecan 4 (ryudocan/amphiglycan) is present in focal adhesions of a number of cell types and represents a new transmembrane focal adhesion component, probably involved in their assembly.
Abstract: Focal adhesion formation in fibroblasts results from complex transmembrane signaling processes initiated by extracellular matrix molecules. Although a role for integrins with attendant tyrosine kinases has been established, there is evidence that cell surface heparan sulfate proteoglycans (HSPGs) are also involved with an associated role of protein kinase C. The identity of the proteoglycan has remained elusive, but we now report that syndecan 4 (ryudocan/amphiglycan) is present in focal adhesions of a number of cell types. Affinity-purified antibodies raised against a unique portion of the cytoplasmic domain of syndecan 4 core protein recognized an HSPG of similar characteristics to those of syndecan 4. These antibodies stained focal adhesions only after cell permeabilization and recognized differing mammalian species. Syndecan 4 was associated with focal adhesions that contained either beta 1 or beta 3 integrin subunits and those that formed on substrates of fibronectin, laminin, vitronectin, or type I collagen. No focal adhesions were found that were vinculin-containing but lacked syndecan 4. In contrast, syndecan 2, whose cytoplasmic domain is closely homologous to syndecan 4, does not appear to be a focal adhesion component. Thus, syndecan 4 represents a new transmembrane focal adhesion component, probably involved in their assembly.

Journal ArticleDOI
TL;DR: The signaling pathways which lead to motility and cell proliferation diverge at the immediate post-receptor stage, and it is suggested that this is accomplished by differential activation of effector molecules.
Abstract: We recently have demonstrated that EGF receptor (EGFR)-induced cell motility requires receptor kinase activity and autophosphorylation (P. Chen, K. Gupta, and A. Wells. 1994. J. Cell Biol. 124:547-555). This suggests that the immediate downstream effector molecule contains a src homology-2 domain. Phospholipase C gamma (PLC gamma) is among the candidate transducers of this signal because of its potential roles in modulating cytoskeletal dynamics. We utilized signaling-restricted EGFR mutants expressed in receptor devoid NR6 cells to determine if PLC activation is necessary for EGFR-mediated cell movement. Exposure to EGF (25 nM) augmented PLC activity in all five EGFR mutant cell lines which also responded by increased cell movement. Basal phosphoinositide turnover was not affected by EGF in the lines which do not present the enhanced motility response. The correlation between EGFR-mediated cell motility and PLC activity suggested, but did not prove, a causal link. A specific inhibitor of PLC, U73122 (1 microM) diminished both the EGF-induced motility and PLC responses, while its inactive analogue U73343 had no effect on these responses. Both the PLC and motility responses were decreased by expression of a dominant-negative PLC gamma-1 fragment in EGF-responsive infectant lines. Lastly, anti-sense oligonucleotides (20 microM) to PLC gamma-1 reduced both responses in NR6 cells expressing wild-type EGFR. These findings strongly support PLC gamma as the immediate post receptor effector in this motogenic pathway. We have demonstrated previously that EGFR-mediated cell motility and mitogenic signaling pathways are separable. The point of divergence is undefined. All kinase-active EGFR mutants induced the mitogenic response while only those which are autophosphorylated induced PLC activity. U73122 did not affect EGF-induced thymidine incorporation in these motility-responsive infectant cell lines. In addition, the dominant-negative PLC gamma-1 fragment did not diminish EGF-induced thymidine incorporation. All kinase active EGFR stimulated mitogen-activated protein (MAP) kinase activity, regardless of whether the receptors induced cell movement; this EGF-induced MAP kinase activity was not affected by U73122 at concentrations that depressed the motility response. Thus, the signaling pathways which lead to motility and cell proliferation diverge at the immediate post-receptor stage, and we suggest that this is accomplished by differential activation of effector molecules.

Book ChapterDOI
TL;DR: This chapter reviews the different classes of amphipathic helices in apolipoproteins, using a combination of powerful computer programs to develop a comparison database and to analyze these structures.
Abstract: Publisher Summary The dominant structural motif of the peripheral apolipoproteins is the amphipathic helix, which is responsible for the reversible association of these proteins with lipids, as well as for many biological functions mediated by these apolipoproteins. This chapter reviews the different classes of amphipathic helices, using a combination of powerful computer programs to develop a comparison database and to analyze these structures. It also discusses their evolutionary origins, physical-chemical properties, X-ray structure determination, and conformational analysis. Although the structures of these lipoprotein classes are similar, they differ in relative proportion of lipids, in the apolipoprotein: lipid ratio and in the apolipoprotein species. The amphipathic α helix plays a pivotal role in the structure and functions of the exchangeable apolipoproteins. Site-directed mutagenesis and other molecular biology-based techniques are available for probing the structural motif. The location and properties of the amphipathic helices in apolipoproteins and the results are compared with recently developed and ever-expanding computer methods for the location and characterization. A variety of structure-function studies, including the activation of lipoprotein lipase, receptor recognition, lecithin-cholesterol acyltransferase (LCAT) activation, and antiviral and anti-inflammatory activities are also discussed.