RESUMEN
The incretins are a class of hormones released from the small bowel that act on the endocrine pancreas to potentiate insulin secretion in a glucose-dependent manner. Due to the requirement for an elevated glucose concentration for activity, the incretins, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1, have potential in the treatment of non-insulin-dependent diabetes mellitus. A series of synthetic peptide GIP fragments was generated for the purpose of elucidating the bioactive domain of the molecule. Peptides were screened for stimulation of cyclic AMP (cAMP) accumulation in Chinese hamster ovary cells transfected with the rat islet GIP receptor. Of the GIP fragments tested, GIP(1-14) and GIP(19-30) demonstrated the greatest cAMP-stimulating ability over the range of concentrations tested (up to 20 microM). In contrast, GIP fragments corresponding to amino acids 15-42, 15-30, 16-30 and 17-30 all demonstrated weak antagonism of GIP(1-42) activity. Competitive-binding displacement studies indicated that these peptides were low-affinity ligands for the GIP receptor. To examine biological activity in vivo, a bioassay was developed in the anesthetized rat. Intravenous infusion of GIP(1-42) (1 pmol/min/100 g) with a concurrent intraperitoneal glucose load (1 g/kg) significantly reduced circulating blood glucose excursions through stimulation of insulin release. Higher doses of GIP(1-14) and GIP(19-30) (100 pmol/min/100 g) also reduced blood glucose excursions.
Asunto(s)
Polipéptido Inhibidor Gástrico/química , Secuencia de Aminoácidos , Animales , Sitios de Unión , Unión Competitiva , Células CHO/metabolismo , Cricetinae , AMP Cíclico/metabolismo , Polipéptido Inhibidor Gástrico/genética , Polipéptido Inhibidor Gástrico/farmacología , Infusiones Intravenosas , Insulina/análisis , Insulina/sangre , Insulina/metabolismo , Secreción de Insulina , Masculino , Datos de Secuencia Molecular , Páncreas/efectos de los fármacos , Páncreas/metabolismo , Fragmentos de Péptidos/síntesis química , Fragmentos de Péptidos/metabolismo , Perfusión , Ratas , Ratas Wistar , Receptores de la Hormona Gastrointestinal/biosíntesis , Receptores de la Hormona Gastrointestinal/genética , Relación Estructura-Actividad , TransfecciónAsunto(s)
Dipeptidil Peptidasa 4/metabolismo , Polipéptido Inhibidor Gástrico/metabolismo , Fragmentos de Péptidos/farmacología , Sustitución de Aminoácidos , Animales , Unión Competitiva , Células CHO , Cricetinae , AMP Cíclico/metabolismo , Diabetes Mellitus Tipo 2 , Diseño de Fármacos , Polipéptido Inhibidor Gástrico/química , Humanos , Hidrólisis , Fragmentos de Péptidos/síntesis química , Fragmentos de Péptidos/metabolismo , Ratas , Receptores de la Hormona Gastrointestinal/efectos de los fármacos , Receptores de la Hormona Gastrointestinal/genética , Receptores de la Hormona Gastrointestinal/metabolismo , Proteínas Recombinantes de Fusión/metabolismo , Sistemas de Mensajero Secundario/efectos de los fármacos , Espectrometría de Masa por Láser de Matriz Asistida de Ionización DesorciónRESUMEN
The potential of double-wavelength interferometry is well known, especially regarding the capability of performing absolute distance measurements of rough targets with high resolutions. We describe the experimental results obtained with a demonstration model of a double-wavelength interferometer with superheterodyne detection. Our system, implemented with two four-quadrant detectors to improve the detection probability, has demonstrated the ability to reach resolutions of 0.2 mm at 5-m distances on rough targets in 50-ms integration time.
RESUMEN
The purpose of this study was to compare, using cell blot analysis, the association of gingival tissue mononuclear cells (GTMC) isolated from lesions displaying histories of early-onset periodontitis (EOP; typically B-lymphocyte dominated) and gingivitis (typically T-lymphocyte dominated) with the B-cell stimulating cytokine, interleukin (IL)-4, and the T-cell stimulating cytokine, IL-2. Eleven EOP patients and 11 age- and gender-similar gingivitis control (GC) subjects participated. Gingival tissue adjacent to the alveolar crest normally removed during surgery was digested in collagenase-containing media and GTMC were isolated by density gradient centrifugation. Cells were separated into four aliquots. One was left unstimulated; the remainder were stimulated for 2 hours with Porphyromonas gingivalis outer membrane protein, mitogen Concanavalin A, or common antigen tetanus toxoid. Cells then were centrifuged onto transfer membranes and incubated in RPMI 1640 media for 6 hours to allow absorption of secreted cytokine. Membranes were treated with monoclonal anti-IL-2 or anti-IL-4, followed by a biotin-conjugated second layer, streptavidin-alkaline phosphatase and nitro blue tetrazolium/5-bromo-4-chloro-indolyl-phosphate (NBT/BCIP) color development. A higher percentage of GTMC from EOP patients were IL-2+ when stimulated with P. gingivalis compared with GTMC from GC patients (20 +/- 2% vs. 12 +/- 2%, P < 0.003). A higher percentage of non-stimulated GTMC from EOP patients produced IL-4 than from GC (22 +/- 4% vs. 6 +/- 3%, P < 0.00007), as well as when stimulated with P. gingivalis (22 +/- 3% vs. 13 +/- 2%, P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)