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Tolcher AW, Bendell JC, Papadopoulos KP, Burris HA, Patnaik A, Jones SF, Rasco D, Cox DS, Durante M, Bellew KM, Park J, Le NT, Infante JR. A phase IB trial of the oral MEK inhibitor trametinib (GSK1120212) in combination with everolimus in patients with advanced solid tumors. Ann Oncol 2015; 26:58-64. [PMID: 25344362 DOI: 10.1093/annonc/mdu482] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND This phase Ib trial investigated the safety, tolerability, and recommended phase II dose and schedule of the MEK inhibitor trametinib in combination with the mammalian target of rapamycin (mTOR) inhibitor everolimus. Secondary objectives included pharmacokinetic (PK) characterization and evaluation of clinical activity. PATIENTS AND METHODS A total of 67 patients with advanced solid tumors were enrolled in this open-label, single-arm, dose-escalation study. Dose escalation followed a 3 + 3 design. Patients were assigned to one of 10 different cohorts, involving either daily dosing with both agents or daily dosing with trametinib and intermittent everolimus dosing. This included an expansion cohort comprising patients with pancreatic tumors. PKs samples were collected predose, as well as 1, 2, 4, and 6 h post-dose on day 15 of the first treatment cycle. RESULTS Concurrent treatment with trametinib and everolimus resulted in frequent treatment-related adverse events, including mucosal inflammation (40%), stomatitis (25%), fatigue (54%), and diarrhea (42%). PK assessment did not suggest drug-drug interactions between these two agents. Of the 67 enrolled patients, 5 (7%) achieved partial response (PR) to treatment and 21 (31%) displayed stable disease (SD). Among the 21 patients with pancreatic cancer, PR was observed in 1 patient (5%) and SD in 6 patients (29%). CONCLUSIONS This study was unable to identify a recommended phase II dose and schedule of trametinib in combination with everolimus that provided an acceptable tolerability and adequate drug exposure.
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Affiliation(s)
- A W Tolcher
- South Texas Accelerated Research Therapeutics LLC, San Antonio.
| | - J C Bendell
- Sarah Cannon Research Institute/Tennessee Oncology, PLLC, Nashville
| | | | - H A Burris
- Sarah Cannon Research Institute/Tennessee Oncology, PLLC, Nashville
| | - A Patnaik
- South Texas Accelerated Research Therapeutics LLC, San Antonio
| | - S F Jones
- Sarah Cannon Research Institute/Tennessee Oncology, PLLC, Nashville
| | - D Rasco
- South Texas Accelerated Research Therapeutics LLC, San Antonio
| | - D S Cox
- GlaxoSmithKline, Collegeville
| | | | - K M Bellew
- Pharmaceutical Companies of Johnson and Johnson, Greater Philadelphia Area
| | - J Park
- GlaxoSmithKline, Collegeville
| | - N T Le
- Novartis, East Hanover, USA
| | - J R Infante
- Sarah Cannon Research Institute/Tennessee Oncology, PLLC, Nashville
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Young G, Boshkov LK, Sullivan JE, Raffini LJ, Cox DS, Boyle DA, Kallender H, Tarka EA, Soffer J, Hursting MJ. Argatroban therapy in pediatric patients requiring nonheparin anticoagulation: an open-label, safety, efficacy, and pharmacokinetic study. Pediatr Blood Cancer 2011; 56:1103-9. [PMID: 21488155 DOI: 10.1002/pbc.22852] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Accepted: 09/02/2010] [Indexed: 11/06/2022]
Abstract
BACKGROUND An increasing number of pediatric patients suffer from thrombotic events necessitating anticoagulation therapy including heparins. Some such patients develop heparin-induced thrombocytopenia (HIT) and thus require alternative anticoagulation. As such, studies evaluating the safety, efficacy, and dosing of alternative anticoagulants are required. PROCEDURE In this multicenter, single arm, open-label study, 18 patients ≤ 16 years old received argatroban for either a suspicion of or being at risk for HIT, or other conditions requiring nonheparin anticoagulation. Endpoints included thrombosis, thromboembolic complications, and bleeding. RESULTS Patients (ages, 1.6 weeks to 16 years) received argatroban usually for continuous anticoagulation (n = 13) or cardiac catheterization (n = 4). One catheterization patient received a 250 µg/kg bolus only; 17 patients received argatroban continuous infusion (median (range)) 1.1 (0.3-12) µg/kg/min (of whom four received a bolus) for 3.0 (0.1-13.8) days. In patients without bolus dosing, typically argatroban 1 µg/kg/min was initiated, with therapeutic activated partial thromboplastin times (aPTTs) (1.5-3× baseline) achieved within 7 hr. Within 30 days, thrombosis occurred in five patients (two during therapy). No one required amputation or died due to thrombosis during therapy. Two patients had major bleeding. Pharmacometric analyses demonstrated the optimal initial argatroban dose to be 0.75 µg/kg/min (if normal hepatic function), with dose reduction necessary in hepatic impairment. CONCLUSIONS In pediatric patients requiring nonheparin anticoagulation, argatroban rapidly provides adequate levels of anticoagulation and is generally well tolerated. For continuous anticoagulation, argatroban 0.75 µg/kg/min (0.2 µg/kg/min in hepatic impairment), adjusted to achieve therapeutic aPTTs, is recommended.
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Affiliation(s)
- G Young
- Division of Hematology/Oncology, Children's Hospital Los Angeles, Los Angeles, California, USA.
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Kurzrock R, Patnaik A, Rosenstein L, Fu S, Papadopoulos KP, Smith DA, Falchook GS, Chambers G, Gauvin JL, Naing A, Smith LS, Gonzalez T, Tsimberidou AM, Mays TA, Cox DS, Hong DS, DeMarini DJ, Le NT, Morris SR, Tolcher AW. Phase I dose-escalation of the oral MEK1/2 inhibitor GSK1120212 (GSK212) dosed in combination with the oral AKT inhibitor GSK2141795 (GSK795). J Clin Oncol 2011. [DOI: 10.1200/jco.2011.29.15_suppl.3085] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Tolcher AW, Bendell JC, Patnaik A, Papadopoulos K, Bellew KM, Cox DS, Xu Y, Burris HA, Le N, Infante JR. A phase Ib study of the MEK inhibitor GSK1120212 combined with gemcitabine in patients with solid tumors: Interim results. J Clin Oncol 2011. [DOI: 10.1200/jco.2011.29.4_suppl.278] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
278 Background: GSK1120212 (212) is a reversible, allosteric inhibitor of MEK1/MEK2. The objectives of this open-label, single-arm study are to evaluate the safety, pharmacokinetics (PK), and anti-tumor activity of 212 + gemcitabine (gem), and to determine the recommended phase II regimen (RP2R) in patients (pts) with advanced solid tumors. Methods: 212 (1-2.5mg) is given continuously, orally, once daily. Gem (1,000mg/m2) is infused on days 1, 8, and 15 every 28 days. Doses are escalated to the maximum tolerated dose (MTD) and followed by an expansion cohort to confirm the RP2R tolerability. Results: 28 pts received ≥ 1 dose of 212 + gem, including 8 pancreatic, 6 breast, and 4 non-small cell lung (NSCLC) cancer pts. The MTD and RP2R is 2mg 212 + 1,000mg/m2 gem. Dose-limiting toxicities (DLTs) are G3/G4 febrile neutropenia (n=2), G3 AST elevation (n=2), and G2 uveitis (n=1). 16 serious adverse events (SAEs) were reported; 5 were considered to be related to study drugs (1 pneumonitis, 3 febrile neutropenia, 1 dyspnea). All DLTs and SAEs have resolved. The most common AEs at the RP2R (n=18) were rash (78%), fatigue (67%), thrombocytopenia (61%), neutropenia (50%), decreased appetite (50%), nausea (44%), diarrhea and constipation (39%); all ≤ G2 except thrombocytopenia (17% ≥ G3) and neutropenia (33% ≥ G3). Co-administration did not affect the PK profiles of 212 or gem. 25 pts had measurable disease at baseline. 1 pancreatic cancer pt with previous radiotherapy and 2 cycles of gem achieved a partial response and stayed on study for 6 months. 3 additional pancreatic cancer pts reported stable disease; 2 of which were on the study for 3.5-5 months and the third pt continues in the study. 1 triple-negative breast cancer pt, refractory to chemotherapy, and 1 parotid cancer pt experienced a complete response of their target lesions. Conclusions: 212 + gem is tolerable with an acceptable safety profile in this pt population, with evidence of clinical activity in pancreatic cancer. A randomized phase II study in previously untreated patients with metastatic pancreatic cancer is underway to investigate the clinical activity of this combination. [Table: see text]
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Affiliation(s)
- A. W. Tolcher
- The START Center for Cancer Care, San Antonio, TX; Sarah Cannon Research Institute, Nashville, TN; GlaxoSmithKline Research and Development, Collegeville, PA
| | - J. C. Bendell
- The START Center for Cancer Care, San Antonio, TX; Sarah Cannon Research Institute, Nashville, TN; GlaxoSmithKline Research and Development, Collegeville, PA
| | - A. Patnaik
- The START Center for Cancer Care, San Antonio, TX; Sarah Cannon Research Institute, Nashville, TN; GlaxoSmithKline Research and Development, Collegeville, PA
| | - K. Papadopoulos
- The START Center for Cancer Care, San Antonio, TX; Sarah Cannon Research Institute, Nashville, TN; GlaxoSmithKline Research and Development, Collegeville, PA
| | - K. M. Bellew
- The START Center for Cancer Care, San Antonio, TX; Sarah Cannon Research Institute, Nashville, TN; GlaxoSmithKline Research and Development, Collegeville, PA
| | - D. S. Cox
- The START Center for Cancer Care, San Antonio, TX; Sarah Cannon Research Institute, Nashville, TN; GlaxoSmithKline Research and Development, Collegeville, PA
| | - Y. Xu
- The START Center for Cancer Care, San Antonio, TX; Sarah Cannon Research Institute, Nashville, TN; GlaxoSmithKline Research and Development, Collegeville, PA
| | - H. A. Burris
- The START Center for Cancer Care, San Antonio, TX; Sarah Cannon Research Institute, Nashville, TN; GlaxoSmithKline Research and Development, Collegeville, PA
| | - N. Le
- The START Center for Cancer Care, San Antonio, TX; Sarah Cannon Research Institute, Nashville, TN; GlaxoSmithKline Research and Development, Collegeville, PA
| | - J. R. Infante
- The START Center for Cancer Care, San Antonio, TX; Sarah Cannon Research Institute, Nashville, TN; GlaxoSmithKline Research and Development, Collegeville, PA
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Infante JR, Fecher LA, Nallapareddy S, Gordon MS, Flaherty KT, Cox DS, DeMarini DJ, Morris SR, Burris HA, Messersmith WA. Safety and efficacy results from the first-in-human study of the oral MEK 1/2 inhibitor GSK1120212. J Clin Oncol 2010. [DOI: 10.1200/jco.2010.28.15_suppl.2503] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Thompson DS, Flaherty K, Messersmith W, Harlacker K, Nallapareddy S, Vincent C, DeMarini DJ, Cox DS, O'Neill VJ, Burris HA. A three-part, phase I, dose-escalation study of GSK1120212, a potent MEK inhibitor, administered orally to subjects with solid tumors or lymphoma. J Clin Oncol 2009. [DOI: 10.1200/jco.2009.27.15_suppl.e14584] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
e14584 Background: GSK1120212 is a potent and highly selective inhibitor of MEK1, a component of the MAP kinase pathway. GSK1120212 demonstrates efficient inhibition of p-ERK which correlates with inhibition of cell proliferation and induction of apoptosis. PO administration of GSK1120212 achieved tumor regression in multiple mouse xenograft models. The objectives of this study are to define the maximum tolerated dose (MTD) and to evaluate the pharmacokinetics (PK) and pharmacodynamic (PD) effects of GSK1120212. Methods: In Part 1, patients (pts) with solid tumors or lymphoma are enrolled in successive cohorts and receive a single PO dose of GSK1120212 followed by QD doses on days 1 - 21 of each 28-day cycle. Tumor response is assessed Q 8 weeks. PK blood samples are collected from all pts. Ophthalmic exams are administered at baseline and as clinically warranted. Dose escalation occurs via an accelerated titration followed by a standard 3+3 escalation. In Part 2, pts with pancreatic or K-Ras mutant CRC will be enrolled at the MTD. In Part 3, pts with biopsiable tumors will enroll at MTD and sub-MTD doses. Tumor biopsies will be taken pre- and post-dose to measure pERK and other markers of cell proliferation. Results: Six pts with advanced malignancies (neuroendocrine, thyroid, colorectal (n=2), melanoma (n=2) have been treated with tablets at four dose levels: 0.125 (n=2), 0.25 (n=1), 0.5 (n=2), and 1.0 mg (n=1). No DLTs or grade 2 toxicities have been reported. One patient was on study for over 17 weeks. Based on mean AUC and Cmax, GSK1120212 exposures following 15 days of repeat-dose administration were approximately dose proportional across the dose range (0.125–0.5 mg) with a median Tmax of approximately 1.5 hours. Conclusions: GSK1120212 has been well tolerated to date. Dose escalation is ongoing. [Table: see text]
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Affiliation(s)
- D. S. Thompson
- Sarah Cannon Research Institute, Nashville, TN; University of Pennsylvania, Philadelphia, PA; University of Colorado Cancer Center, Aurora, CO; GlaxoSmithKline, Research Triangle Park, NC; GlaxoSmithKline, Collegeville, PA; GlaxoSmithKline, King of Prussia, PA
| | - K. Flaherty
- Sarah Cannon Research Institute, Nashville, TN; University of Pennsylvania, Philadelphia, PA; University of Colorado Cancer Center, Aurora, CO; GlaxoSmithKline, Research Triangle Park, NC; GlaxoSmithKline, Collegeville, PA; GlaxoSmithKline, King of Prussia, PA
| | - W. Messersmith
- Sarah Cannon Research Institute, Nashville, TN; University of Pennsylvania, Philadelphia, PA; University of Colorado Cancer Center, Aurora, CO; GlaxoSmithKline, Research Triangle Park, NC; GlaxoSmithKline, Collegeville, PA; GlaxoSmithKline, King of Prussia, PA
| | - K. Harlacker
- Sarah Cannon Research Institute, Nashville, TN; University of Pennsylvania, Philadelphia, PA; University of Colorado Cancer Center, Aurora, CO; GlaxoSmithKline, Research Triangle Park, NC; GlaxoSmithKline, Collegeville, PA; GlaxoSmithKline, King of Prussia, PA
| | - S. Nallapareddy
- Sarah Cannon Research Institute, Nashville, TN; University of Pennsylvania, Philadelphia, PA; University of Colorado Cancer Center, Aurora, CO; GlaxoSmithKline, Research Triangle Park, NC; GlaxoSmithKline, Collegeville, PA; GlaxoSmithKline, King of Prussia, PA
| | - C. Vincent
- Sarah Cannon Research Institute, Nashville, TN; University of Pennsylvania, Philadelphia, PA; University of Colorado Cancer Center, Aurora, CO; GlaxoSmithKline, Research Triangle Park, NC; GlaxoSmithKline, Collegeville, PA; GlaxoSmithKline, King of Prussia, PA
| | - D. J. DeMarini
- Sarah Cannon Research Institute, Nashville, TN; University of Pennsylvania, Philadelphia, PA; University of Colorado Cancer Center, Aurora, CO; GlaxoSmithKline, Research Triangle Park, NC; GlaxoSmithKline, Collegeville, PA; GlaxoSmithKline, King of Prussia, PA
| | - D. S. Cox
- Sarah Cannon Research Institute, Nashville, TN; University of Pennsylvania, Philadelphia, PA; University of Colorado Cancer Center, Aurora, CO; GlaxoSmithKline, Research Triangle Park, NC; GlaxoSmithKline, Collegeville, PA; GlaxoSmithKline, King of Prussia, PA
| | - V. J. O'Neill
- Sarah Cannon Research Institute, Nashville, TN; University of Pennsylvania, Philadelphia, PA; University of Colorado Cancer Center, Aurora, CO; GlaxoSmithKline, Research Triangle Park, NC; GlaxoSmithKline, Collegeville, PA; GlaxoSmithKline, King of Prussia, PA
| | - H. A. Burris
- Sarah Cannon Research Institute, Nashville, TN; University of Pennsylvania, Philadelphia, PA; University of Colorado Cancer Center, Aurora, CO; GlaxoSmithKline, Research Triangle Park, NC; GlaxoSmithKline, Collegeville, PA; GlaxoSmithKline, King of Prussia, PA
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Stone AA, Marco CA, Cruise CE, Cox DS, Neale JM. Are stress-induced immunological changes mediated by mood? A closer look at how both desirable and undesirable daily events influence sIgA antibody. Int J Behav Med 2006; 3:1-13. [PMID: 16250763 DOI: 10.1207/s15327558ijbm0301_1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
This investigation tested a three-path model of mood as a mediator of the relation between stress and immunity. Seventy-two married men completed end-of-day diaries in which they rated their mood for that day and the desirability of the day's events for I2 weeks. Events were coded as either desirable (nonstressful) or undesirable (stressful) in nature. Immunological functioning was assessed by secretory immunoglobulin-A NgA) antibody response lo an oral antigen. Regression analyses indicated that negative mood partially mediated the immunological response to both undesirable and desirable events. Undesirable events lowered antibody levels primarily by increasing negative mood: desirable events increased antibody levels by decreasing negative mood. Evidence for mediation by positive mood beyond that found for negative mood was weak.
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Affiliation(s)
- A A Stone
- Department of Psychiatry and Behavioral Science, State University of New York, Stony Brook 11794-8790, USA
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Cox DS, Scott KR, Gao H, Raje S, Eddington ND. Influence of multidrug resistance (MDR) proteins at the blood-brain barrier on the transport and brain distribution of enaminone anticonvulsants. J Pharm Sci 2001; 90:1540-52. [PMID: 11745712 DOI: 10.1002/jps.1104] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Previous in vitro studies evaluating the permeability of enaminones suggested that their blood-brain barrier (BBB) transport might be influenced by the presence of an efflux mechanism. Therefore, transport mechanisms responsible for these anticonvulsants across the BBB were examined. The transport of enaminones (1 x 10(-4) M) were evaluated over 120 min with verapamil (50 microM) and probenecid (100 microM) using bovine brain microvessel endothelial cells (BBMECs) to assess the role of multidrug resistant (MDR) transport proteins [i.e., P-glycoprotein (Pgp) and MDR protein 1 (MRP1)] on efflux, respectively. Uptake studies in the presence and absence of rhodamine 123 (R123; 3.2 and 5.0 microM) were also performed in a Pgp overexpressing cell line, MCF-7/Adr. Select enaminone esters (12.5 mg/kg) were administered intravenously to mdr 1 a/b (+/+), mdr 1 a/b (-/-) knockout and probenecid pretreated mice (20 +/- 5g). Enaminones and R123 were assayed with validated ultraviolet and fluorescence high-performance liquid chromatography methods, respectively. Verapamil and probenecid significantly ( p>0.05) inhibited the transport of select enaminone esters across BBMECs. Two enaminones caused a statistically significant increase in the uptake of R123 in MCF-7/Adr cells. Concentrations of select enaminones in mdr 1 a/b (-/-) mice brains were significantly higher ( p<0.05) compared with those in mdr 1 a/b (+/+) mice brains; however, no differences were observed in probenecid pretreated animals. Taken together, these results strongly suggest that Pgp may influence enaminone transport at the BBB and hence affect epilepsy treatment with these agents.
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Affiliation(s)
- D S Cox
- Pharmacokinetics Biopharmaceutics Laboratory, Department of Pharmaceutical Science, School of Pharmacy, University of Maryland, 100 Penn Street, AHB, Baltimore, Maryland 21201, USA
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Cox DS, Gao H, Raje S, Scott KR, Eddington ND. Enhancing the permeation of marker compounds and enaminone anticonvulsants across Caco-2 monolayers by modulating tight junctions using zonula occludens toxin. Eur J Pharm Biopharm 2001; 52:145-50. [PMID: 11522479 DOI: 10.1016/s0939-6411(01)00172-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Zonula occludens toxin (Zot), a protein elaborated from Vibrio cholerae, has been shown to be capable of reversibly opening tight junctions between intestinal cells The objective of this study was to examine the effect of Zot on the flux of various molecules across Caco-2 cell monolayers. In addition, the transport of a series of anticonvulsants, the enaminones was also evaluated in the presence of Zot. The flux of [(14)C]mannitol, [(14)C]inulin and various enaminones across Caco-2 cell monolayers (n=6) was examined after pre-incubation for 1h with Zot (0 or 4000ng/ml) or phosphate-buffered saline (PBS). At the end of the incubation period, the flux of radiolabeled compounds or enaminones (1x10(-4)M) was assessed over a 2-h period. In addition, dose-response studies with Zot (0, 1000, 2000 or 4000ng/ml) were performed using mannitol. The flux of both mannitol and inulin significantly increased (P<0.05) in the presence of Zot. The transport of the enaminones with Zot ranged from 9.42 to 26.83x10(-5)cm/s vs. 4.68 to 13.83x10(-5)cm/s without Zot. Zot significantly increased the transport of all agents tested. This suggests that the co-administration of drugs with Zot may be a useful delivery strategy to increase the intestinal permeability and hence oral absorption of poorly bioavailable agents.
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Affiliation(s)
- D S Cox
- Pharmacokinetics Biopharmaceutics Laboratory, Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, 100 Penn Street, Baltimore, MD, USA
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Cox DS, Du J, Scott KR, Gao H, Eddington ND. Determination of the enaminone DM5, an anti-epileptic agent, in mouse plasma and brain tissue by high-performance liquid chromatography with ultraviolet detection. J Chromatogr B Biomed Sci Appl 2000; 749:191-6. [PMID: 11145056 DOI: 10.1016/s0378-4347(00)00411-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Enaminone derivatives of the 4-carbomethoxy-5-methylcyclohexane-1,3-dione series represent a new and potentially active series of compounds for the treatment of Epilepsy. Enaminone esters have been previously evaluated as compounds with potent oral anticonvulsant activity similar to class 1 anticonvulsants phenytoin, carbamazepine, and lamotrigine. DM5, a member of this class with -Cl in the para-substituted position, has been assessed to have the most potent pharmacological activity (ED50) in both the mouse and rat. A selective and specific high-performance liquid chromatography method was developed to quantitate DM5 in plasma and brain tissue in mice. Reverse phase chromatography with ultraviolet (lambda = 307 nm) detection was utilized to quantitate eluate. A C18 analytical column was used and the mobile phase consisted of acetonitrile and 0.05 M NaH2PO4 buffer (60:40; v/v). Liquid-liquid extraction with ether was used to extract the DM5 from plasma or brain homogenates. DM5 and carbamazepine (internal standard) eluted at approximately 6.0 and 9.0 min without any interfering peaks. The calibration curves were found to be linear (r > or = 0.9999) in the range of 0.1-5.0 microg/ml or microg/g. Intra-run precision's were in all in the range of 90%. The absolute recovery of the analyte in brain and plasma samples was < or = 90%. The valid method accurately quantified DM5 in plasma and brain tissue samples collected from a pharmacokinetic study consisting of an intravenous bolus in the tail vein of wild type and genetically altered mice.
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Affiliation(s)
- D S Cox
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, 21201, USA
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Abstract
Enaminones, enamines of ss-dicarbonyl compounds, have been know for many years. In our initial account (Current Med. Chem. 1994, 1, 159-175), we reported on the anticonvulsant activity of a series of enaminones, notably methyl 4-[(p-chlorophenyl)amino]-6-methyl-2-oxo-cyclohex-3-en- 1-oate, 9a (R=CH3, R1=4-Cl), which, in animal tests, compared favorably to phenytoin and carbamazepine. Since that time, further research in our laboratory and other laboratories have expanded the therapeutic potential of these compounds. In addition to new anticonvulsant derivatives, we have uncovered a novel brain transport mechanism for the enaminones and developed a preliminary regression model for further synthetic direction. These topics will each be presented and elaborated.
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Affiliation(s)
- N D Eddington
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland at Baltimore, Baltimore, MD 21201-4403, USA
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Burstein AH, Cox DS, Mistry B, Eddington ND. Phenytoin pharmacokinetics following oral administration of phenytoin suspension and fosphenytoin solution to rats. Epilepsy Res 1999; 34:129-33. [PMID: 10210027 DOI: 10.1016/s0920-1211(98)00107-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The administration of phenytoin suspension in conjunction with enteral nutrition supplements through nasogastric (NG) feeding tubes to humans has been associated with suboptimal phenytoin absorption, subtherapeutic concentrations, and breakthrough seizures. Postulated mechanisms include chelation to proteins and electrolytes in the enteral feeding, binding to NG tubing, and alterations in gastrointestinal pH resulting in precipitation of phenytoin. The purpose of this pilot study was to evaluate the oral absorption of commercially available fosphenytoin injectable solution compared to phenytoin suspension in the rat to determine whether equivalent oral fosphenytoin and phenytoin suspension doses should be used for future human studies of fosphenytoin oral absorption in the presence of concomitant enteral nutrition. A single oral 30 mg/kg phenytoin equivalents dose of either commercially available fosphenytoin or phenytoin suspension was administered to male Wistar rats following an overnight fast. Blood samples (0.3 ml) for phenytoin plasma concentration were obtained from a jugular vein catheter at baseline and 0.5, 1, 1.5, 2, 3, 4, 5, 8, 12 and 24 h post-study drug administration and analyzed by high performance liquid chromatography (HPLC) (CV% < 6). Mean phenytoin Cmax was 85% [corrected] (P = 0.010) higher in fosphenytoin vs phenytoin treated rats. Tmax was 2.4 h (62%, P=0.021) shorter in fosphenytoin vs phenytoin treated rats. No significant differences in AUClast were found. The presence of a phosphate ester moiety does not appear to inhibit the appearance of phenytoin following oral administration of fosphenytoin. Phenytoin plasma concentration profiles following oral administration of fosphenytoin are characterized by higher Cmax and shorter Tmax values relative to oral administration of phenytoin suspension.
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Affiliation(s)
- A H Burstein
- School of Pharmacy, Department of Pharmacy Practice and Science, University of Maryland, Baltimore 21201-1082, USA.
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Marcus AC, Morra M, Rimer BK, Stricker M, Heimendinger J, Wolfe P, Darrow SL, Hamilton L, Cox DS, Miller N, Perocchia RS. A feasibility test of a brief educational intervention to increase fruit and vegetable consumption among callers to the Cancer Information Service. Prev Med 1998; 27:250-61. [PMID: 9579004 DOI: 10.1006/pmed.1998.0246] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND In this paper, results are reported from a pilot study designed to test the feasibility of a proactive educational intervention delivered to callers of the Cancer Information Service (CIS). METHODS The study used a randomized two-group design (intervention vs control). Callers assigned to the intervention condition received a brief educational intervention at the end of usual service to increase fruit and vegetable consumption. As part of the intervention, key education messages and materials drawn from the 5 A Day for Better Health program of the National Cancer Institute were provided to CIS callers over the telephone and then reinforced with two follow-up mailings. RESULTS Results from this pilot study indicated high levels of adherence to protocol by CIS Information Specialists who delivered the intervention to eligible CIS callers. Results obtained from the 4-week telephone follow-up interviews indicated that intervention subjects (n = 142) reported higher consumption of fruits and vegetables, averaging approximately 0.75 servings more per day (P < 0.01) than control subjects (n = 134). CONCLUSION Nearly 80% of CIS callers endorsed the strategy of providing 5 A Day information at the end of usual service, even if such information was not specifically requested by the caller (i.e., the information was provided to CIS callers proactively.
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Affiliation(s)
- A C Marcus
- AMC Cancer Research Center, Denver, Colorado 80214, USA
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Stone AA, Neale JM, Cox DS, Napoli A, Valdimarsdottir H, Kennedy-Moore E. Daily events are associated with a secretory immune response to an oral antigen in men. Health Psychol 1995. [PMID: 7805639 DOI: 10.1037//0278-6133.13.5.440] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
To examine a hypothesized link between daily stressful events and secretory immunoglobulin A (sIgA) antibody, 96 adults from the community completed daily event questionnaires and gave daily saliva samples for up to 12 weeks. They also ingested a capsule of a novel protein to challenge their secretory immune systems. The questionnaire yielded measures of negative and positive experiences, of their content, and of negative and positive affect. On a within-subjects, day-to-day basis, reporting more desirable events was related to more sIgA antibody, and reporting more undesirable events was related to less. Desirable events also had lagged (1 and 2 days), positive effects on sIgA levels. Undesirable work events and desirable leisure and household events were more strongly related to sIgA than events in other categories. Positive affect related directly to sIgA, and negative mood related inversely to same-day sIgA.
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Affiliation(s)
- A A Stone
- Department of Psychiatry, State University of New York at Stony Brook 11794-8790
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Stone AA, Neale JM, Cox DS, Napoli A, Valdimarsdottir H, Kennedy-Moore E. Daily events are associated with a secretory immune response to an oral antigen in men. Health Psychol 1994; 13:440-6. [PMID: 7805639 DOI: 10.1037/0278-6133.13.5.440] [Citation(s) in RCA: 105] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
To examine a hypothesized link between daily stressful events and secretory immunoglobulin A (sIgA) antibody, 96 adults from the community completed daily event questionnaires and gave daily saliva samples for up to 12 weeks. They also ingested a capsule of a novel protein to challenge their secretory immune systems. The questionnaire yielded measures of negative and positive experiences, of their content, and of negative and positive affect. On a within-subjects, day-to-day basis, reporting more desirable events was related to more sIgA antibody, and reporting more undesirable events was related to less. Desirable events also had lagged (1 and 2 days), positive effects on sIgA levels. Undesirable work events and desirable leisure and household events were more strongly related to sIgA than events in other categories. Positive affect related directly to sIgA, and negative mood related inversely to same-day sIgA.
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Affiliation(s)
- A A Stone
- Department of Psychiatry, State University of New York at Stony Brook 11794-8790
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Cox DS. TQM: a primer. J Assoc Healthc Philanthr 1994:21-4. [PMID: 10125181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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Cox DS. The annual appeal: a communications tool. J Assoc Healthc Philanthr 1992:37-8. [PMID: 10124369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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Yamashita K, Eastcott JW, Taubman MA, Smith DJ, Cox DS. Effect of adoptive transfer of cloned Actinobacillus actinomycetemcomitans-specific T helper cells on periodontal disease. Infect Immun 1991; 59:1529-34. [PMID: 1825991 PMCID: PMC257872 DOI: 10.1128/iai.59.4.1529-1534.1991] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Previously we isolated several Actinobacillus actinomycetemcomitans-specific T-cell clones from the spleens and lymph nodes of immunized Rowett rats. These clones were characterized as W3/13+, W3/25+, OX8-, and OX22-, suggesting a T helper (Th) phenotype. In the current experiments, 10(6) cells from a single A. actinomycetemcomitans-specific clone (A3) were adoptively transferred to a group (AaTh; n = 13) of normal heterozygous rats (rnu/+) at 28 days of age. A second group received no T cells (AaNT; n = 15), and a third group also received no T cells (NAaNT, n = 11). Beginning 1 day after transfer, the first and second groups were infected orally with A. actinomycetemcomitans for 5 consecutive days. The presence of infection was confirmed immediately after challenge and after 5 months, when the experiments were ended. Significantly higher numbers of lymphocytes were recovered from the gingival tissues of the first group than from those of either of the other groups. Also, this group showed significantly elevated (P less than 0.01) serum immunoglobulin G and immunoglobulin M antibody to A. actinomycetemcomitans in an enzyme-linked immunosorbent assay when compared with both other groups. Bone loss was significantly lower (P less than 0.01) in recipients of A. actinomycetemcomitans-specific cloned cells when compared with the other infected group and was approximately equal to the bone loss of the uninfected group. These results are consistent with the hypothesis that T-cell regulation can affect periodontal disease. In this regulation, T helper cells appear to interfere with periodontal bone loss.
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Affiliation(s)
- K Yamashita
- Department of Immunology, Forsyth Dental Center, Boston, Massachusetts 02115
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Stone AA, Schwartz JE, Valdimarsdottir H, Napoli A, Neale JM, Cox DS. An alternative statistical treatment for summarizing the central tendency of replicate assay data. J Immunol Methods 1991; 136:111-7. [PMID: 1995704 DOI: 10.1016/0022-1759(91)90256-f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Standard assay procedures call for multiple replicates for the purpose of averaging random error from individual replicate scores to obtain a reliable estimate of the true score and for the purpose of specifying the degree of variability within the assay. In this paper we focus on the variability and magnitude of within-assay replicates in order to improve the estimate of the true score. A rule is presented for deciding (1) when individual replicates should be omitted from the computation of the assay's summary score or (2) when an entire sample of replicates should be discarded based on the pattern of replicate scores. It is suggested that this rule improves the reliability of the estimated assay score and this is supported by an illustrative analysis of lymphocyte proliferation assays.
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Affiliation(s)
- A A Stone
- Department of Psychiatry, State University of New York, Stony Brook 11794-8790
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Neale JM, Cox DS, Valdimarsdottir H, Stone AA. The relation between immunity and health: comment on Pennebaker, Kiecolt-Glaser, and Glaser. J Consult Clin Psychol 1988. [PMID: 3198828 DOI: 10.1037//0022-006x.56.4.636] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Neale JM, Cox DS, Valdimarsdottir H, Stone AA. The relation between immunity and health: Comment on Pennebaker, Kiecolt-Glaser, and Glaser. J Consult Clin Psychol 1988; 56:636-7. [PMID: 3198828 DOI: 10.1037/0022-006x.56.4.636] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Abstract
The field of psychoimmunology has rapidly expanded in recent years and various parameters of the immune system have been examined in relation to psychological factors. The secretory immune system is one of the more interesting aspects of the entire immune system because it protects mucosal membranes from invading organisms. Stress-produced changes in secretory immunoglobulin A (s-IgA) as measured by radial immunodiffusion assays have been reported in several studies. We present three reasons why total s-IgA protein, the measure derived from radial immunodiffusion assays, may not be a reasonable measure of immune system functioning, and we suggest an alternative method for examining secretory IgA that focuses on s-IgA antibody response to a novel antigen.
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Affiliation(s)
- A A Stone
- Department of Psychiatry and Behavioral Science, State University of New York at Stony Brook
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Stone AA, Cox DS, Valdimarsdottir H, Jandorf L, Neale JM. Evidence that secretory IgA antibody is associated with daily mood. J Pers Soc Psychol 1987. [PMID: 3585705 DOI: 10.1037//0022-3514.52.5.988] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
In this study, we examined the secretory immune system, the body's first line of defense against invading organisms, and its relation to daily fluctuations of mood. Specifically, secretory immunoglobulin A (sIgA) was studied. Unlike other psychoimmunity studies that examined all sIgA protein regardless of specificity to invading organisms, ours examined an antigen-specific sIgA response to the oral administration of a harmless protein (rabbit albumin) and monitored the antibody produced in response to the protein. Dental students recorded their daily mood thrice weekly for 8 1/3 weeks, and parotid saliva was obtained from subjects during these contacts. Using a within-subjects analyses strategy, we found that antibody response was lower on days with high negative mood relative to days with lower negative mood, and conversely, sIgA antibody response was higher on days with high positive mood relative to days with lower positive mood. Results from total sIgA protein were in the opposite direction, although not significantly so. These results extend our knowledge of immunological changes and mood, and they suggest that minor life events' role in health may be mediated by the secretory immune system.
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Abstract
In this study, we examined the secretory immune system, the body's first line of defense against invading organisms, and its relation to daily fluctuations of mood. Specifically, secretory immunoglobulin A (sIgA) was studied. Unlike other psychoimmunity studies that examined all sIgA protein regardless of specificity to invading organisms, ours examined an antigen-specific sIgA response to the oral administration of a harmless protein (rabbit albumin) and monitored the antibody produced in response to the protein. Dental students recorded their daily mood thrice weekly for 8 1/3 weeks, and parotid saliva was obtained from subjects during these contacts. Using a within-subjects analyses strategy, we found that antibody response was lower on days with high negative mood relative to days with lower negative mood, and conversely, sIgA antibody response was higher on days with high positive mood relative to days with lower positive mood. Results from total sIgA protein were in the opposite direction, although not significantly so. These results extend our knowledge of immunological changes and mood, and they suggest that minor life events' role in health may be mediated by the secretory immune system.
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Abstract
Sprague-Dawley rats were administered DNP-BGG on day one of pregnancy by either local mammary gland vicinity injection or by gastric intubation. All rats later received local mammary gland vicinity injection of DNP-BGG on day 11 of pregnancy. Milk and serum were collected post-parturition. IgA and IgG antibody was separated in the milk and IgG antibody in the serum. The relative average affinity constant (KO) was determined by a modification of the Farr assay. Milk IgG affinity was found to be considerably higher than the affinity of IgG in the serum. IgA affinity in the milk of rats which received the antigen by gastric intubation demonstrated antibody affinity much greater than the affinity of milk antibody in rats which simply received mammary gland vicinity injection (1.8 x 10(8) vs. 1.4 x 10(6) l/M). The results indicate that much of the IgG antibody in milk may be locally synthesized. Gut-associated lymphoid tissue may act as a source of antigen specific memory cells for peripheral secretory tissues.
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Cox DS, Vansant KC. Resources: cancer prevention. Md Med J 1985; 34:83-90. [PMID: 3849650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Abstract
The 25-item Hopkins Symptom Checklist ( HSCL -25) was used on two occasions four weeks apart to identify self-reported symptoms of anxiety and depression in patients attending a family planning service. Only 28 per cent of patients classified as anxious to start with remained so four weeks later, but 62 per cent of those with high depression scores and 74 per cent of those with high depression and high anxiety scores maintained significant levels of depression. The implications of these findings for routine screening are discussed.
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Cox DS. How we met a donor's challenge. J Natl Assoc Hosp Dev 1984:15, 17. [PMID: 10310035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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29
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Cox DS, Taubman MA. Oral induction of the secretory antibody response by soluble and particulate antigens. Int Arch Allergy Appl Immunol 1984; 75:126-31. [PMID: 6206000 DOI: 10.1159/000233602] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The ability of gastric intubation of a soluble or a particulate form of dinitrophenylated bovine gamma-globulin (DNP-BGG) to induce salivary IgA antibody was examined. Gastric intubation of the particulate form of the antigen tended to induce a greater response than did equivalent doses of the soluble form. However, systemic immunization with the soluble form of the antigen prior to gastric intubation of antigen increased the salivary IgA response. Prior systemic injection of the particulate form did not increase the salivary IgA response. Immunoreactivity of the particulate moiety of the particulate antigen did not seem to be a factor in the observed differences, since three different synthetic particulate antigens with identical hapten-protein moieties produced the same results (i.e. prior injection with the synthetic particulate antigens did not increase the salivary IgA response).
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Abstract
The effect of the introduction of antigen by gastric intubation on the locally stimulated mammary gland IgA antibody (Ab) response was examined. Rats receiving a particulate DNP antigen by gastric intubation prior to injection in the vicinity of the mammary glands ( MGV ) demonstrated increased levels of IgA Ab in milk. Soluble DNP antigen introduction by gastric intubation did not lead to increased IgA Ab levels in milk. Prior administration of either form of DNP antigen by gastric intubation did not affect the IgG response. Only those rats receiving particulate DNP antigen by intubation demonstrated salivary IgA Ab. Particulate forms of antigen administered by intubation can provide a means of increasing the locally induced IgA response at a secretory site.
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Abstract
A sensitive modification of the ammonium sulfate precipitation assay for antibody affinity is described. The assay combines small reaction volumes and a 32P volume marker to determine the average relative affinity of small amounts of antibody to DNP hapten. The assay is relatively safe since two beta-particle emitters are utilized instead of two gamma-ray emitters. The assay has proven useful for the determination of small amounts of antibody such as might be found in secretions and column fractions.
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Cox DS, Taubman MA. Systemic priming of the secretory antibody response with soluble and particulate antigens and carriers. The Journal of Immunology 1982. [DOI: 10.4049/jimmunol.128.4.1844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Cox DS, Taubman MA. Systemic priming of the secretory antibody response with soluble and particulate antigens and carriers. J Immunol 1982; 128:1844-8. [PMID: 6174617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Abstract
The salivary antibody response produced after remote secretory site (mammary gland) injection of soluble or particulate DNP antigens was examined in the rat. IgA and IgG salivary antibody and IgG serum antibody concentrations were determined by an ELISA technique. Two experiments were performed using DNP-BGG as the soluble antigen and either DNP-S. mutans or DNP-BGG-S. mutans as particulate antigens. Approximately equivalent IgA antibody responses were produced when soluble or particulate antigens were injected locally at a secretory site. However, a greater salivary IgA response was observed with the soluble antigen when the antigens were injected in the vicinity of a secretory site (mammary glands) remote from the salivary glands (experiment 1: 123 +/- 46 vs 2 +/- 1 ng IgA per millilitre of saliva, and experiment 2: 212 +/- 59 vs 45 +/- 21 ng IgA per millilitre of saliva). In both experiments, prior remote secretory site injection of the soluble antigen was able to prime for a significantly increased salivary IgA response (more than three-fold) after a local injection in the vicinity of the salivary gland. The particulate antigens did not lead to priming of the salivary antibody response. Prior remote secretory site injection of soluble antigen, but not of the particulate antigens, also increased salivary and serum IgG antibody levels above the levels observed with an injection at either site alone.
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Abstract
We have investigated the binding of 125I-concanavalin A (125I-Con A) and 125I-succinyl concanavalin A (125I-s-Con A) to rat fibroblasts (16C line) as a function of the concentration of added lectin, and the alterations to this binding behaviour caused by drugs which modify the cytoskeleton. The changes in cell behaviour which occur at different levels of binding have also been studied. As shown previously for some other systems, the binding of Con A is complex and partly co-operative. Three phases can be distinguished in our system: (i) pre-nucleation binding, (ii) binding which shows a small positive slope in a Scatchard plot and a Hill coefficient greater than unity, and which therefore is incipiently co-operative, and (iii) post-co-operative binding. The co-operative phase of binding is paralleled by progressive inhibition of EGTA-mediated cell detachment from substrata, with inhibition being complete when this phase of binding is complete. Likewise, the phagocytosis of latex spheres is progressively inhibited up to a threshold which coincides with the completion of co-operative binding. Thirdly, cells pretreated with Con A round up with colchicine (10(−5) M) if co-operative finding is complete, but adopt broad epithelial shapes if it is not. s-Con A does not show cooperative binding, and correspondingly does not inhibit EGTA-mediated cell detachment, or show a distinct threshold in the inhibition of phagocytosis, or promote the 2 types of shape change with colchicine. The pattern of Con A binding is drastically altered by pretreatment of cells with cytochalasin B or azide. The Scatchard and Hill plots show that the co-operative phase remains and is complete at about the same level of binding, but that it is more readily nucleated and takes place against a changed number and/or distribution of receptors. Pretreatment of cells with colchicine causes changes in the pattern of binding which are different from those observed with cytochalasin B or azide and are more difficult to interpret. We conclude that a reciprocal relationship exists between the cellular actomyosin and the state of cell surface receptors. Perturbation of actomyosin by cytochalasin B or azide can enhance the freedom of some receptors to participate in a co-operative rearrangement which facilitates the binding of further molecules of lectin. Vice versa, the co-operative event has a feedback influence on the cellular actomyosin to cause alterations of cellular response.
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