scholarly journals Specific Binding of Autographa californica M Nucleopolyhedrovirus Occlusion-Derived Virus to Midgut Cells of Heliothis virescens Larvae Is Mediated by Products of pif Genes Ac119 and Ac022 but Not by Ac115

2005 ◽  
Vol 79 (24) ◽  
pp. 15258-15264 ◽  
Author(s):  
Taro Ohkawa ◽  
Jan O. Washburn ◽  
Ronika Sitapara ◽  
Eric Sid ◽  
Loy E. Volkman
Keyword(s):  
Heliothis Virescens ◽  
Specific Binding ◽  
Autographa Californica ◽  
Early Event ◽  
Target Cells ◽  
Primary Target ◽  
Specific Receptors ◽  
Attachment Proteins ◽  
By Products

ABSTRACT Per os infectivity factors PIF1 (Ac119) and PIF2 (Ac022), like P74, are essential for oral infection of lepidopteran larval hosts of Autographa californica M nucleopolyhedrovirus (AcMNPV). Here we show that Ac115 also is a PIF (PIF3) and that, unlike PIF1 and PIF2, it does not mediate specific binding of AcMNPV occlusion-derived virus (ODV) to midgut target cells. We used an improved in vivo fluorescence dequenching assay to compare binding, fusion, and competition among control AcMNPV ODV and the ODVs of AcMNPV PIF1, PIF2, and PIF3 deletion mutants. Our results showed that binding and fusion of PIF1 and PIF2 mutants, but not the PIF3 mutant, were both qualitatively and quantitatively different from those of control ODV. Unlike control and PIF3-deficient ODV, an excess of PIF1- or PIF2-deficient ODV failed to compete effectively with control ODV's binding to specific receptors on midgut epithelial cells. Moreover, the levels of PIF1- and PIF2-deficient ODV binding were depressed threefold compared to control levels. Binding, fusion, and competition by PIF3-deficient ODV, however, were all indistinguishable from those of control ODV. These results implicated PIF1 and PIF2 as ODV envelope attachment proteins that mediate specific binding to primary target cells within the midgut. In contrast, PIF3 mediates another unidentified, but critical, early event during primary infection.

scholarly journals P74 Mediates Specific Binding of Autographa californica M Nucleopolyhedrovirus Occlusion-Derived Virus to Primary Cellular Targets in the Midgut Epithelia of Heliothis virescens Larvae

2004 ◽  
Vol 78 (13) ◽  
pp. 6786-6791 ◽  
Author(s):  
Eric J. Haas-Stapleton ◽  
Jan O. Washburn ◽  
Loy E. Volkman
Keyword(s):  
Heliothis Virescens ◽  
Trichoplusia Ni ◽  
Specific Binding ◽  
Autographa Californica ◽  
Target Cells ◽  
Wild Type ◽  
Specific Receptor ◽  
Cellular Targets

ABSTRACT P74, an envelope protein of the occlusion-derived virus (ODV) of Autographa californica M nucleopolyhedrovirus (AcMNPV), is critical for oral infection of Trichoplusia ni larvae. The role of P74 during primary infection, however, is unknown. Here we provide evidence that P74 facilitates binding of AcMNPV ODV to a specific receptor within the larval midgut epithelia of another host species, Heliothis virescens. We adapted a fluorescence dequenching assay to compare binding, fusion, and competition of wild-type AcMNPV ODV in vivo with itself and with the ODV of a p74-deficient AcMNPV mutant. We found that relative to wild-type ODV, binding and fusion of ODV deficient in P74 were both qualitatively and quantitatively different. Unlike wild-type ODV, an excess of P74-deficient ODV failed to compete effectively with wild-type ODV binding, and the overall binding level of the mutant ODV was one-third that of the wild type. These results implicated P74 as an ODV attachment protein that binds to a specific receptor on primary target cells within the midgut.

scholarly journals Direct in vivo demonstration by radioautography of specific binding sites for calcitonin in skeletal and renal tissues of the rat.

1980 ◽  
Vol 85 (3) ◽  
pp. 682-694 ◽  
Author(s):  
H Warshawsky ◽  
D Goltzman ◽  
M F Rouleau ◽  
J J Bergeron
Keyword(s):  
Binding Sites ◽  
Alveolar Bone ◽  
Specific Binding ◽  
Biologically Active ◽  
Target Cells ◽  
Rat Tissues ◽  
Specific Binding Sites ◽  
Calcitonin Receptors

An in vivo binding assay using radioautography was employed to visualize calcitonin receptors in rat tissues. At 2 min after intravenous injection of biologically active 125I-salmon calcitonin, free hormone was separated from bound hormone by intracardiac perfusion with lactated Ringer's followed by fixation with 2.5% glutaraldehyde. Various tissues were removed and processed for light and electron microscope radioautography. These were compared to tissues removed from animals that received identical amounts of labeled hormone with a large excess of unlabeled calcitonin. Among the tissues investigated, kidney and bone demonstrated labeling. In kidney, most silver grains were located over vesicles below the brush border of cells of theproximal convoluted tubules. These grains were still present after simultaneous injection of excess unlabeled hormone and most likely represented binding to sites involved with ingestion and degradation of hormone from the urinary filtrate. In contrast, grains localized to the basal surfaces of distal convoluted tubule cells were significantly reduced in number in control animals and represented sites of saturable, specific hormone binding. In bone, specific binding sites were found only at the periphery of osteoclasts. These labeled cells were located at resorption sites examined in tibia, humerus, and alveolar bone. This demonstration of the localization of 124I-calcitonin in situ provides a new approach for study the interaction of calcium-regulating hormones with their target cells.

IL-10 Present in the B Lymphoma Microenvironment Drives Macrophages to Efficient Tumour Suppressing Cells with High Phagocytic Activity in Presence of Rituximab.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1582-1582
Author(s):  
Josee Golay ◽  
Marzia Leidi ◽  
Elisa Gotti ◽  
Giuseppe Palumbo ◽  
Martino Introna
Keyword(s):  
Specific Binding ◽  
Alternative Activation ◽  
Target Cells ◽  
Blood Monocytes ◽  
Phagocytic Capacity ◽  
B Lymphoma ◽  
Human Macrophages ◽  
Gm Csf

Abstract Since macrophages have been implicated as major players in the mechanism of action of Rituximab (Mabthera®) in vivo, we have investigated the factors that modulate their tumour cell killing potential in vitro. Human macrophages expressing CD16, CD32 and CD64, were differentiated from CD14+ peripheral blood monocytes by culture for 5–7 days in presence of M-CSF. Binding of rituximab opsonised target cells was measured after 5 minutes incubation of macrophages with CFSE labelled B-CLL cells and FACS analysis. Phagocytosis was quantified after 2 hours at 37°C by microscopic count of stained slide preparations. ADCC was measured by standard release assays. Rituximab induced specific binding of CD20+ target cells to macrophages and this was followed by phagocytosis, but not ADCC. Phagocytosis was maximal at 0.1 μg/ml rituximab and was not significantly affected by CD20 expression levels on target cells. The CD16A polymorphism at amino acid 158 (Val/Phe) that affects IgG binding did not significantly modify the efficacy of phagocytosis at different rituximab doses, possibly due to the role of additional Fcγ receptors. Indeed phagocytosis was blocked by excess human immunoglobulins. Since macrophages can be differentiated to M1 type or M2 type cells with either GM-CSF or M-CSF, respectively, and can be classically activated by pro-inflammatory stimuli (IFNγ + LPS) or undergo alternative activation with cytokines such as IL-4 or IL-10, we have analysed the effect of these different polarisation programs on the phagocytosis mediated by rituximab. Macrophages differentiated in presence of M-CSF showed a 2–3 fold greater phagocytic capacity compared to GM-CSF induced cells. Furthermore addition of IL-10 significantly increased, whereas IL-4 decreased phagocytosis by both M-CSF and GM-CSF differentiated macrophages. LPS/IFNγ had little effect. Expression of CD16, CD32A/C and CD64 correlated with the phagocytic capacity of the different polarised populations, suggesting that M-CSF and IL-10 induced maximal phagocytosis through upregulation of several activating FcγRs. Several B lymphoma cell lines were observed to secrete 400–1300 pg/ml IL-10 in vitro and co-culture of human macrophages with lymphoma supernatant increased significantly their phagocytic capacity. These data suggest that IL-10 produced in the lymphoma microenviroment may activate macrophages to become M2 type cells with high phagocytic capacity. Thus usually tumour promoting M2 type macrophages within the lymphoma would become tumour suppressing in presence of rituximab.

scholarly journals Nef Enhances Human Immunodeficiency Virus Type 1 Infectivity Resulting from Intervirion Fusion: Evidence Supporting a Role for Nef at the Virion Envelope

2001 ◽  
Vol 75 (13) ◽  
pp. 5851-5859 ◽  
Author(s):  
Jing Zhou ◽  
Christopher Aiken
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Leukemia Virus ◽  
Early Event ◽  
Target Cells ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT The human immunodeficiency virus type 1 (HIV-1) accessory protein Nef stimulates viral infectivity by facilitating an early event in the HIV-1 life cycle. Although no structural or biochemical defects in Nef-defective HIV-1 particles have been demonstrated, the Nef protein is incorporated into HIV-1 particles. To localize the function of Nef within the virus particle, we developed a novel technology involving fusion of enveloped donor HIV-1 particles bearing core defects with envelope-defective target virions bearing HIV-1 receptors. Although neither virus alone was capable of infecting CD4+ target cells, the incubation of donor and target virions prior to addition to target cells resulted in infection. This effect, termed “virion transcomplementation,” required a functional Env protein on the donor virus and CD4 and an appropriate coreceptor on target virions. To provide evidence for intervirion fusion as the mechanism of complementation, experiments were performed using dual-enveloped HIV-1 particles bearing both HIV-1 and ecotropic murine leukemia virus (E-MLV) Env proteins as donor virions. Infection of CD4-negative target cells bearing E-MLV receptors was prevented by HIV-1 entry inhibitors when added before, but not after, incubation of donor and target virions prior to the addition to cells. When we used Nef+and Nef− donor and target virions, Nef enhanced infection when present in donor virions. In contrast, no effect of Nef was detected when present in the target virus. These results reveal a potential mechanism for enhancing HIV-1 diversity in vivo through the rescue of defective viral genomes and provide a novel genetic system for the functional analysis of virion-associated proteins in HIV-1 infection.

Interaction of anabolic steroids with glucocorticoid receptor sites in rat muscle cytosol

1975 ◽  
Vol 229 (5) ◽  
pp. 1381-1386 ◽  
Author(s):  
M Mayer ◽  
F Rosen
Keyword(s):  
Skeletal Muscle ◽  
Glucocorticoid Receptors ◽  
Specific Binding ◽  
Anabolic Steroids ◽  
Repeated Administration ◽  
Glucocorticoid Hormones ◽  
Receptor Sites ◽  
Specific Receptors

While glucocorticoid hormones act catabolically on skeletal muscle through their binding to glucocorticoid-specific receptors in the cytosol, androgens exert anabolic responses but no androgen-specific binding proteins could be detected in this responsive tissue. However, various nonradioactive androgens were effective in displacing labeled dexamethasone or cortisol from their respective cytoplasmic receptors in muscle, both in vitro and in vivo. The inhibition of glucocorticoid binding by androgens is competitive, and could be observed following a single or repeated administration of the androgens to adrenalectomized-castrated animals. The synthetic androgen fluoxymesterone and the hormone testosterone displayed Ki values of 7.5 X 10(-6) M and 1 X 10(-5) M, respectively, for the inhibition of [3H]dexamethasone binding in muscle cytosol. On the basis of competition experiments it is postulated that interaction of androgens with glucocorticoid receptors prevents the binding of glucocorticoids and might be responsible in part for the anabolic effects of pharmacologic doses of androgens in muscle.

Renal potassium adaptation: role of the Na+-K+ pump in rat cortical collecting tubules

1989 ◽  
Vol 256 (2) ◽  
pp. F279-F284 ◽  
Author(s):  
Y. Fujii ◽  
S. K. Mujais ◽  
A. I. Katz
Keyword(s):  
Specific Binding ◽  
Intrinsic Property ◽  
Hydrolytic Activity ◽  
Early Event ◽  
Base Line ◽  
Potassium Adaptation ◽  
High K ◽  
K Secretion ◽  
Collecting Tubules

To evaluate the mechanism of renal potassium adaptation we explored several facets of Na+-K+-ATPase function during K loading in rat cortical collecting tubule (CCT). Urinary K excretion increased within the 1st day after initiation of dietary loading to a level matching intake, indicating the early onset of K adaptation. CCT Na+-K+-ATPase activity after 1 and 2 days on the high-K diet was not different from that observed in control animals, whereas it increased to threefold base line after 7 days. Similarly, the specific binding of ouabain was unchanged by 2 days of high-K diet, but was increased on the 7th day. In contrast, there was an early increase in Rb uptake that persisted throughout the period of observation. Acute (60 min) KCl infusion into control rats led to a significant increase in Rb uptake, whereas Na+-K+-ATPase hydrolytic activity remained unchanged. In the isolated perfused kidney, increasing perfusate K led to an increase in CCT Rb uptake similar to that observed in vivo, again without altering the hydrolytic activity of the enzyme. We conclude that K adaptation is an early event developing rapidly after initiation of dietary change. In its early phase the Na+-K+ pump responds by increasing K-transport rate to accommodate the acute homeostatic need; when the requirement for increased K secretion is sustained, a different adaptive pattern emerges characterized by an increase in the number of pumps. The adaptive response to an acute K load appears to be an intrinsic property of the pump independent of hormonal influences.

Atrial natriuretic factor receptors in cultured renomedullary interstitial cells

1990 ◽  
Vol 258 (4) ◽  
pp. C692-C699 ◽  
Author(s):  
B. M. Fontoura ◽  
D. R. Nussenzveig ◽  
K. M. Pelton ◽  
T. Maack
Keyword(s):  
Atrial Natriuretic Factor ◽  
Cultured Cells ◽  
Specific Binding ◽  
Renal Medulla ◽  
Interstitial Cells ◽  
Effective Dosage ◽  
Target Cells ◽  
Natriuretic Factor ◽  
Atrial Natriuretic

To gain further insight on the cell types that may mediate the effects of atrial natriuretic factor (ANF) in the renal medulla, we determined the distribution and function of biological (B) and clearance (C) receptors of ANF in renomedullary interstitial cells (RMIC). Studies were performed in the 3rd-17th passages of RMIC obtained from a primary culture of the rat renal medulla. Electron microscopy of the cultured cells showed the typical morphological features of RMIC "in vivo," including prominent lipid droplets. RMIC have a very high density of high-affinity specific binding sites of ANF-(1-28) [23,000 sites/cell; dissociation constant (Kd) = 50 pM]. There was only minimal binding of C-ANF-(4-23) (less than 2,500 sites/cell), a specific ligand of C-ANF receptors. ANF-(1-28) markedly increased guanosine 3',5'-cyclic monophosphate (cGMP) from 1.3 +/- 0.3 to 106 +/- 22 pmol cGMP/10(6) cells [50% effective dosage (ED50) = 1.2 nM]. The effect of ANF-(1-28) on cGMP was nearly additive to that of sodium nitroprusside and was not potentiated or antagonized by C-ANF-(4-23). The density of guanylate cyclase-coupled B-ANF receptors and the ANF-induced increase in cGMP in RMIC are higher than those reported to date in other target cells. This suggests that RMIC may mediate some of the known effects of ANF in the renal medulla.

scholarly journals Detection of PD-L1 expression in temozolomide-resistant glioblastoma by using PD-L1 antibodies conjugated with lipid-coated superparamagnetic iron oxide

2021 ◽  
Author(s):  
Gilbert Lee ◽  
Wan-Li Lin ◽  
Duen-Pang Kuo ◽  
Yi-Tien Li ◽  
Yu-Wei Chang ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Binding Capacity ◽  
Specific Binding ◽  
Superparamagnetic Iron Oxide ◽  
Blue Staining ◽  
Target Cells ◽  
Poor Prognostic Factor ◽  
Mri Diagnosis

Abstract Background: Targeted superparamagnetic iron oxide (SPIO) nanoparticles are a promising tool for molecular magnetic resonance imaging (MRI) diagnosis. Lipid-coated SPIO nanoparticles have a nonfouling property that can reduce nonspecific binding to off-target cells and prevent agglomeration, making them suitable contrast agents for molecular MRI diagnosis. PD-L1 is a poor prognostic factor for patients with glioblastoma. Most recurrent glioblastomas are temozolomide-resistant. Diagnostic probes targeting PD-L1 could help early diagnosis and be used to predict the responses of targeted PD-L1 immunotherapy in patients with primary and recurrent glioblastoma. In this study, we conjugated lipid-coated SPIO nanoparticles with PDL1 antibodies to identify PDL1 expression in glioblastoma or temozolomide-resistant glioblastoma by using MRI.Results: The synthesized PD-L1 antibody–conjugated SPIO (PDL1-SPIO) nanoparticles were characterized using dynamic light scattering, zeta potential assays, transmission electron microscopy images, in vitro cell affinity assay, and in vivo MRI analysis. These data demonstrated that PDL1-SPIO has a specific binding capacity to PD-L1 of the mouse glioblastoma cell line (GL261). The presence and quantity of PDL1-SPIO in temozolomide-resistant glioblastoma cells and tumor tissue were confirmed through Prussian blue staining and in vivo T2* map MRI, respectively.Conclusions: These findings revealed that PDL1-SPIO can specifically target temozolomide-resistant glioblastoma with PD-L1 expression and can be quantified with MRI analysis, thereby making it suitable for the diagnosis of PD-L1 expression in temozolomide-resistant glioblastoma in vivo.

Correlation between in vitro and in vivo Data of Radiolabeled Peptide for Tumor Targeting

2019 ◽  
Vol 19 (12) ◽  
pp. 950-960
Author(s):  
Soghra Farzipour ◽  
Seyed Jalal Hosseinimehr
Keyword(s):  
Tumor Targeting ◽  
Single Photon ◽  
Specific Binding ◽  
Specific Interaction ◽  
Photon Emission ◽  
Emission Computed Tomography ◽  
Mixed Effect ◽  
Radiolabeled Peptides

Tumor-targeting peptides have been generally developed for the overexpression of tumor specific receptors in cancer cells. The use of specific radiolabeled peptide allows tumor visualization by single photon emission computed tomography (SPECT) and positron emission tomography (PET) tools. The high affinity and specific binding of radiolabeled peptide are focusing on tumoral receptors. The character of the peptide itself, in particular, its complex molecular structure and behaviors influence on its specific interaction with receptors which are overexpressed in tumor. This review summarizes various strategies which are applied for the expansion of radiolabeled peptides for tumor targeting based on in vitro and in vivo specific tumor data and then their data were compared to find any correlation between these experiments. With a careful look at previous studies, it can be found that in vitro unblock-block ratio was unable to correlate the tumor to muscle ratio and the success of radiolabeled peptide for in vivo tumor targeting. The introduction of modifiers’ approaches, nature of peptides, and type of chelators and co-ligands have mixed effect on the in vitro and in vivo specificity of radiolabeled peptides.

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