RESUMEN
PURPOSE: Over 40% of newly diagnosed metastatic breast cancer patients are ≥ 70 years old; however, this population is less likely to be represented in clinical trials. The objective of this study was to analyze PFS, dose reductions, dose delays, and toxicity in a geriatric population receiving palbociclib in a non-trial setting. METHODS: Patients with metastatic breast cancer receiving palbociclib in any line of therapy were identified from a cohort of 845 patients at a large academic institution. Dose delays, dose reductions, and toxicities were retrospectively extracted from the medical record. Data were analyzed using Fischer's exact test for categorized variables and T test/Wilcoxon rank-sum test for continuous variables. PFS and OS were analyzed using the Kaplan-Meier method. RESULTS: 605 patients who met eligibility criteria were included. 160 patients were ≥ 65 years old and 92 patients were ≥ 70 years old. Patients ≥ 70 had a significantly increased number of dose reductions (p = 0.03) and dose delays (p = 0.02) compared to the younger patients. There was no significant increase in toxicities, including neutropenic fever, infections, or hospitalizations, in the ≥ 70 cohort (p = 0.3). The ≥ 70 cohort had a significantly improved PFS as compared to the younger cohort (p = 0.02); however, age was no longer a significant variable in the multivariate analysis. CONCLUSIONS: Palbociclib was well tolerated in the geriatric population and there was no difference in PFS between older and younger patients. These results are reassuring as palbociclib becomes the frontline standard of care therapy for patients.
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Neoplasias de la Mama/tratamiento farmacológico , Piperazinas/administración & dosificación , Inhibidores de Proteínas Quinasas/administración & dosificación , Piridinas/administración & dosificación , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Persona de Mediana Edad , Piperazinas/efectos adversos , Inhibidores de Proteínas Quinasas/efectos adversos , Piridinas/efectos adversos , Estudios Retrospectivos , Análisis de Supervivencia , Resultado del TratamientoRESUMEN
BACKGROUND: We aimed to evaluate the associations between systemic sclerosis (SSc)-related systemic manifestations and esophageal function using high-resolution manometry (HRM). METHODS: Patients with SSc that had undergone HRM between 1/2004 and 9/2014 were identified and HRMs were analyzed according to the Chicago Classification. Clinical characteristics were identified via retrospective chart review and compared among motility diagnoses while adjusting for age, gender, race, and SSc-disease duration. KEY RESULTS: Seventy-nine patients (85% female, ages 25-77) were included. Clinical characteristics were compared between patients with absent contractility (AC, n = 40), ineffective esophageal motility (IEM; n = 15), and normal motility (n = 19); the five remaining patients met criteria for other motility diagnoses. Groups differed in severity of skin involvement measured by the modified Rodnan skin score (0-51): AC (adjusted mean 12.6), IEM (4.4), normal (4.3), p = 0.043. Pulmonary function tests [percent predicted FVC and DLCO) were lower in AC (adjusted mean, FVC: 70.3, DLCO 51.1), than IEM (FVC: 92.0; DLCO: 76.9) and normal motility (FVC: 80.0; DLCO: 67.2), p values 0.057 (FVC) and 0.007 (DLCO). Groups did not differ by SSc-disease duration, autoantibodies, or reported symptoms of dysphagia or reflux. CONCLUSIONS & INFERENCES: In patients with SSc, absent esophageal contractility on HRM was associated with increased skin disease severity and worse lung function. Obtaining HRM to identify SSc patients with more severe esophageal dysfunction could be considered to enable implementation of management strategies in patients potentially at risk for increased morbidity and mortality.
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Trastornos de la Motilidad Esofágica/fisiopatología , Esófago/fisiopatología , Esclerodermia Sistémica/fisiopatología , Adulto , Anciano , Trastornos de la Motilidad Esofágica/complicaciones , Femenino , Humanos , Masculino , Manometría , Persona de Mediana Edad , Estudios Retrospectivos , Esclerodermia Sistémica/complicacionesRESUMEN
The use of extracorporeal carbon dioxide removal (ECCO2R) is well established as a therapy for patients suffering from acute respiratory failure. Development of next generation low blood flow (<500 mL/min) ECCO2R devices necessitates more efficient gas exchange devices. Since over 90% of blood CO2 is transported as bicarbonate (HCO3(-)), we previously reported development of a carbonic anhydrase (CA) immobilized bioactive hollow fiber membrane (HFM) which significantly accelerates CO2 removal from blood in model gas exchange devices by converting bicarbonate to CO2 directly at the HFM surface. This present study tested the hypothesis that dilute sulfur dioxide (SO2) in oxygen sweep gas could further increase CO2 removal by creating an acidic microenvironment within the diffusional boundary layer adjacent to the HFM surface, facilitating dehydration of bicarbonate to CO2. CA was covalently immobilized onto poly (methyl pentene) (PMP) HFMs through glutaraldehyde activated chitosan spacers, potted in model gas exchange devices (0.0151 m(2)) and tested for CO2 removal rate with oxygen (O2) sweep gas and a 2.2% SO2 in oxygen sweep gas mixture. Using pure O2 sweep gas, CA-PMP increased CO2 removal by 31% (258 mL/min/m(2)) compared to PMP (197 mL/min/m(2)) (P<0.05). Using 2.2% SO2 acidic sweep gas increased PMP CO2 removal by 17% (230 mL/min/m(2)) compared to pure oxygen sweep gas control (P<0.05); device outlet blood pH was 7.38 units. When employing both CA-PMP and 2.2% SO2 sweep gas, CO2 removal increased by 109% (411 mL/min/m(2)) (P<0.05); device outlet blood pH was 7.35 units. Dilute acidic sweep gas increases CO2 removal, and when used in combination with bioactive CA-HFMs has a synergistic effect to more than double CO2 removal while maintaining physiologic pH. Through these technologies the next generation of intravascular and paracorporeal respiratory assist devices can remove more CO2 with smaller blood contacting surface areas. STATEMENT OF SIGNIFICANCE: A clinical need exists for more efficient respiratory assist devices which utilize low blood flow rates (<500 mL/min) to regulate blood CO2 in patients suffering from acute lung failure. Literature has demonstrated approaches to chemically increase hollow fiber membrane (HFM) CO2 removal efficiency by shifting equilibrium from bicarbonate to gaseous CO2, through either a bioactive carbonic anhydrase enzyme coating or bulk blood acidification with lactic acid. In this study we demonstrate a novel approach to local blood acidification using an acidified sweep gas in combination with a bioactive coating to more than double CO2 removal efficiency of HFM devices. To our knowledge, this is the first report assessing an acidic sweep gas to increase CO2 removal from blood using HFM devices.
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Dióxido de Carbono/sangre , Anhidrasas Carbónicas/metabolismo , Materiales Biocompatibles Revestidos/química , Gases/química , Membranas Artificiales , Animales , Bovinos , Humanos , Concentración de Iones de Hidrógeno , Sulfitos/sangre , Dióxido de Azufre/químicaRESUMEN
Artificial lung devices comprised of hollow fiber membranes (HFMs) coated with the enzyme carbonic anhydrase (CA), accelerate removal of carbon dioxide (CO2) from blood for the treatment of acute respiratory failure. While previous work demonstrated CA coatings increase HFM CO2 removal by 115 % in phosphate buffered saline (PBS), testing in blood revealed a 36 % increase compared to unmodified HFMs. In this work, we sought to characterize the CO2 mass transport processes within these biocatalytic devices which impede CA coating efficacy and develop approaches towards improving bioactive HFM efficiency. Aminated HFMs were sequentially reacted with glutaraldehyde (GA), chitosan, GA and afterwards incubated with a CA solution, covalently linking CA to the surface. Bioactive CA-HFMs were potted in model gas exchange devices (0.0119 m(2)) and tested for esterase activity and CO2 removal under various flow rates with PBS, whole blood, and solutions containing individual blood components (plasma albumin, red blood cells or free carbonic anhydrase). Results demonstrated that increasing the immobilized enzyme activity did not significantly impact CO2 removal rate, as the diffusional resistance from the liquid boundary layer is the primary impediment to CO2 transport by both unmodified and bioactive HFMs under clinically relevant conditions. Furthermore, endogenous CA within red blood cells competes with HFM immobilized CA to increase CO2 removal. Based on our findings, we propose a bicarbonate/CO2 disequilibrium hypothesis to describe performance of CA-modified devices in both buffer and blood. Improvement in CO2 removal rates using CA-modified devices in blood may be realized by maximizing bicarbonate/CO2 disequilibrium at the fiber surface via strategies such as blood acidification and active mixing within the device.
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Órganos Artificiales , Dióxido de Carbono/metabolismo , Anhidrasa Carbónica II/metabolismo , Pulmón , Animales , Dióxido de Carbono/sangre , Dióxido de Carbono/aislamiento & purificación , Bovinos , Enzimas Inmovilizadas/metabolismo , Humanos , Técnicas In Vitro , Cinética , Ensayo de Materiales , Membranas Artificiales , Intercambio Gaseoso Pulmonar/fisiología , Insuficiencia Respiratoria/fisiopatología , Insuficiencia Respiratoria/terapia , Especificidad de la EspecieRESUMEN
Extracorporeal CO2 removal from circulating blood is a promising therapeutic modality for the treatment of acute respiratory failure. The enzyme carbonic anhydrase accelerates CO2 removal within gas exchange devices by locally catalyzing HCO3 (-) into gaseous CO2 within the blood. In this work, we covalently immobilized carbonic anhydrase on the surface of polypropylene hollow fiber membranes using glutaraldehyde activated chitosan tethering to amplify the density of reactive amine functional groups for enzyme immobilization. XPS and a colorimetric amine assay confirmed higher amine densities on the chitosan coated fiber compared to control fiber. Chitosan/CA coated fibers exhibited accelerated CO2 removal in scaled-down gas exchange devices in buffer and blood (115% enhancement vs. control, 37% enhancement vs. control, respectively). Carbonic anhydrase immobilized directly on hollow fiber membranes without chitosan tethering resulted in no enhancement in CO2 removal. Additionally, fibers coated with chitosan/carbonic anhydrase demonstrated reduced platelet adhesion when exposed to blood compared to control and heparin coated fibers.
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Anhidrasas Carbónicas/metabolismo , Quitosano/química , Enzimas Inmovilizadas/metabolismo , Glutaral/química , Pulmón/química , Membranas Artificiales , Animales , Dióxido de Carbono/aislamiento & purificación , Microscopía Electrónica de Rastreo , Espectroscopía de Fotoelectrones , OvinosRESUMEN
Mannose analogues (2-deoxy-D-glucose, 2-deoxy-2-fluoro-D-glucose and 2-amino-2-deoxy-D-mannose) have been used to study glycosylphosphatidylinositol (GPtdIns) biosynthesis and GPtdIns protein anchoring in protozoal and mammalian systems. The effects of these analogues on GPtdIns biosynthesis and GPtdIns-protein anchoring of the human malaria parasite Plasmodium falciparum were evaluated in this study. At lower concentrations of 2-deoxy-D-glucose and 2-deoxy-2-fluoro-D glucose (0.2 and 0.1 mm, respectively), GPtdIns biosynthesis is inhibited without significant effects on total protein biosynthesis. At higher concentrations of 2-deoxy-D-glucose and 2-deoxy-2-fluoro-D-glucose (1.5 and 0.8 mm, respectively), the incorporation of [3H]glucosamine into glycolipids was inhibited by 90%, and the attachment of GPtdIns anchor to merozoite surface protein-1 (MSP-1) was prevented. However, at these concentrations, both sugar analogues inhibit MSP-1 synthesis and total protein biosynthesis. In contrast to 2-deoxy-2-fluoro-D-glucose and 2-amino-2-deoxy-D-mannose (mannosamine), the formation of new glycolipids was observed only in the presence of tritiated or nonradiolabelled 2-deoxy-D-glucose. Mannosamine inhibits GPtdIns biosynthesis at a concentration of 5 mm, but neither an accumulation of aberrant intermediates nor significant inhibition of total protein biosynthesis was observed in the presence of this analogue. Furthermore, the [3H]mannosamine-labelled glycolipid spectrum resembled the one described for [3H]glucosamine labelling. Total hydrolysis of mannosamine labelled glycolipids showed that half of the tritiated mannosamine incorporated into glycolipids was converted to glucosamine. This high rate of conversion led us to suggest that no actual inhibition from GPtdIns biosynthesis is achieved with the treatment with mannosamine, which is different to what has been observed for mammalian cells and other parasitic protozoa.
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Glicosilfosfatidilinositoles/biosíntesis , Manosa/análogos & derivados , Plasmodium falciparum/efectos de los fármacos , Plasmodium falciparum/metabolismo , Animales , Desoxiglucosa/farmacología , Fluorodesoxiglucosa F18/farmacología , Hexosaminas/farmacología , Manosa/farmacología , Proteína 1 de Superficie de Merozoito/biosíntesis , Proteínas Protozoarias/biosíntesisRESUMEN
Phosphofructokinase from Bacillus stearothermophilus (BsPFK) is a model allosteric enzyme system in which the interactions between substrates and allosteric effectors have been extensively studied. However, the oligomeric nature of BsPFK has made it difficult to determine the molecular basis of the allosteric regulation because of the multitude of different types of heterotropic and homotropic interactions that are possible between the four active sites and four allosteric sites in the native tetramer. In an attempt to alleviate the complexity of the system and thereby allow the quantitation of a single interaction between one active site and one allosteric site, site-directed mutagenesis has been coupled with a hybrid-forming scheme to create and isolate a tetramer of BsPFK in which only a single active site and a single allosteric site are capable of binding their respective ligands with high (i.e., near wild type) affinity. Characterization of this single allosteric interaction indicates that the free energy involved in the inhibition by the allosteric effector phosphoenolpyruvate (PEP) is 1.48 +/- 0.15 kcal/mol compared to the 3.58 +/- 0.02 kcal/mol measured for the enzyme.
Asunto(s)
Geobacillus stearothermophilus/enzimología , Fosfofructoquinasa-1/química , Fosfofructoquinasa-1/metabolismo , Regulación Alostérica , Sitio Alostérico , Sustitución de Aminoácidos , Sitios de Unión , Fructosafosfatos/metabolismo , Cinética , Sustancias Macromoleculares , Mutagénesis Sitio-Dirigida , Fosfoenolpiruvato/metabolismo , Fosfofructoquinasa-1/aislamiento & purificación , Proteínas Recombinantes/química , Proteínas Recombinantes/aislamiento & purificación , Proteínas Recombinantes/metabolismo , TermodinámicaRESUMEN
Various factors influencing the performance of a Hadamard transform time-of-flight mass spectrometer (HT-TOFMS) have been investigated. Using a nitrogen corona discharge to produce an ion stream of N2+, N3+, and N4+, it is found for spectra containing only N4+ that the signal-to-noise ratio (SNR) closely approaches the value calculated from the ion background by assuming that the ion background follows a Poisson distribution. In contrast, for a more intense beam containing N2+, N3+, and N4+, the SNR is less than its theoretical value because of the appearance of discrete spikes in the mass spectrum caused by deviations in the actual modulation sequence from the ideal one. These spikes can be reduced, however, by decreasing the modulation voltage. Under these optimized conditions, the pseudo-random sequence length is varied to understand how it alters SNR, mass resolution, and scan speed. When the length of the pseudo-random sequence is doubled, the SNR increases by the square root of 2 while the time necessary to record a mass spectrum also doubles. Mass resolution can be varied between 500 and 1200 at m/z = 609 as the sequence length, modulation speed (10 MHz, 25 MHz), and acquisition rate (up to 50 MHz) are changed. Scan speeds of 6000 passes per s can be obtained using a sequence containing 4095 elements modulated at 25 MHz. The capability to tailor the HT-TOFMS to increase the scan speed and resolution with a constant 50% duty cycle makes the technique extremely appealing as a mass analyzer for measuring rapid changes in the composition of an ion stream.
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Espectrometría de Masa por Ionización de Electrospray/métodos , Algoritmos , Interpretación Estadística de Datos , Indicadores y Reactivos , Nitrógeno/química , Distribución Aleatoria , Reserpina/químicaRESUMEN
The binding of phosphoenolpyruvate (PEP) to the single allosteric site on phosphofructokinase (EC ) from Bacillus stearothermophilus (BsPFK) diminishes the ability of the enzyme to bind the substrate fructose 6-phosphate (Fru-6-P). Comparisons of crystal structures with either Fru-6-P or phosphoglycolate, an analog of PEP, bound have shown that Arg-162 interacts with the negatively charged Fru-6-P. Upon the binding of phosphoglycolate, Arg-162 is virtually replaced by Glu-161, which introduces a potential coulombic repulsion between enzyme and substrate [Schirmer, T. & Evans, P. R. (1990) Nature (London) 343, 140-145]. It has previously been proposed that this structural transition explains the allosteric inhibition in BsPFK, and this explanation has appeared in textbooks to illustrate how an allosteric ligand can influence substrate binding at a distance. Site-directed mutagenesis has been employed to create three mutants of BsPFK that substitute an alanine residue for Glu-161, Arg-162, or both. The E161A mutation does not affect the inhibition of BsPFK by PEP at 25 degrees C, and while the R162A mutation decreases BsPFK's affinity for Fru-6-P by approximately 30-fold, R162A diminishes the effectiveness of PEP inhibition by only 1/3. Combining E161A and R162A produces behavior comparable to R162A alone. These and other data suggest that the movement of Glu-161 and Arg-162 does not play the central role in producing the allosteric inhibition by PEP as originally envisioned in the Schirmer and Evans mechanism.
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Geobacillus stearothermophilus/enzimología , Fosfofructoquinasa-1/metabolismo , Regulación Alostérica , Humanos , Mutagénesis Sitio-Dirigida , Fosfofructoquinasa-1/genética , Espectrometría de Fluorescencia , TermodinámicaRESUMEN
We are investigating the structure and biosynthesis of glycosyl-phosphatidylinositols (GPI) in the protozoa Toxoplasma gondii, Plasmodium falciparum, Plasmodium yoelii and Paramecium primaurelia. This comparison of structural and biosynthesis data should lead us to common and individual features of the GPI-biosynthesis and transport in different organisms.
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Eucariontes/metabolismo , Glicosilfosfatidilinositoles/metabolismo , Animales , Glicosilfosfatidilinositoles/biosíntesis , Glicosilfosfatidilinositoles/química , Histocitoquímica , Estructura Molecular , Paramecium/metabolismo , Plasmodium falciparum/metabolismo , Plasmodium yoelii/metabolismo , Toxoplasma/metabolismoRESUMEN
Twenty-three tennis players with a symptomatic full-thickness rotator cuff tear underwent anterior acromioplasty and rotator cuff repair. There were 8 small tears (less than 1 cm), 5 moderate tears (1 to 3 cm), 2 large tears (3 to 5 cm), and 8 massive tears (greater than 5 cm). The dominant shoulder was involved in all patients and all were unable to play tennis before surgery. Eleven patients experienced a traumatic event that caused an injury, 6 while playing tennis, and 12 patients had a gradual onset of symptoms. At average follow-up of 42 months, 19 patients (83%) achieved a good result, were pain-free, and were able to play tennis at their presymptomatic competitive level. Three patients (13%), all with massive tears, had a satisfactory result and were able to play tennis, although at a lower competitive level secondary to weakness. One patient (4%), who also had a massive tear, had an unsatisfactory result and was unable to play tennis.
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Lesiones del Manguito de los Rotadores , Traumatismos de los Tendones/cirugía , Tenis/lesiones , Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Dimensión del Dolor , Rango del Movimiento Articular , Manguito de los Rotadores/cirugía , RoturaRESUMEN
In an attempt to further delineate the role of magnetic resonance (MR) imaging in evaluating knee pathology, a retrospective study of 60 patients who underwent MR scanning before arthroscopy was undertaken. For medial meniscus tears, the sensitivity of MR imaging was 97% whereas its specificity was 77%. For lateral meniscus tears, MR imaging was 90% sensitive and 87% specific. The positive predictive value of MR imaging was 85% for medial meniscus tears and only 79% for lateral meniscus tears. The negative predictive value was 95% for the medial meniscus and 94% for the lateral meniscus. MR imaging had an accuracy of 93% in assessing anterior cruciate ligament pathology also. These results begin to clarify the role of MR imaging in evaluating intraarticular knee pathology. Grade III signals represented tears at arthroscopy more than 90% of the time. False-positive results occurred more frequently than false negative results did. The high negative predictive value of MR imaging indicates that with a negative MR image, the orthopaedist can reliably conclude that no meniscal pathology is present. MR imaging is a useful diagnostic tool; however, it should be used selectively and in conjunction with the clinical examination in evaluating internal derangements of the knee.
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Traumatismos de la Rodilla/diagnóstico , Articulación de la Rodilla/patología , Rodilla/patología , Imagen por Resonancia Magnética , Adulto , Lesiones del Ligamento Cruzado Anterior , Artroscopía , Femenino , Humanos , Traumatismos de la Rodilla/epidemiología , Masculino , Valor Predictivo de las Pruebas , Estudios Retrospectivos , Sensibilidad y Especificidad , Lesiones de Menisco TibialRESUMEN
Structural features contributing to the antigenic recognition of the small globular hormone avian pancreatic polypeptide (APP) by a polyclonal antiserum have been defined using a solution phase radioimmunoassay technique. Cross-reactivity studies with PP homologues suggest that the surface residues within the alpha-helix of the peptide may be antigenic, whereas hydrophilicity and atomic mobility predictive methods implicate the molecules beta-turn region. Immunochemical data and circular dichroism measurements on a timed trypsin digest of APP indicate that the secondary structure of the alpha-helix is vital for the molecule's immunological competence. Immunoreactivities of iodinated derivatives of APP, as well as that of peptide fragments of APP and its homologues, support the importance of teritary structure involving the interaction of the polyproline and alpha helices. The highly mobile C-terminal residues 34-36 (His-Arg-Tyr-NH2) have been found by immunological analysis to be unimportant. Arginine residue 33, which has been conserved through vertebrate evolution, is a major antigenic contributor, since a large decrease in immunoreactivity, not accompanied by a significant change in conformation, was observed upon specific removal of this residue by carboxypeptidase B. These results are consistent with a "discontinuous" epitopic model for APP in which Arg-33 and exposed residues in the alpha-helix are principal components of an epitope or epitopes mediated by the secondary and tertiary structures of the molecule.
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Epítopos/análisis , Polipéptido Pancreático/inmunología , Animales , Carboxipeptidasas , Fenómenos Químicos , Química , Reacciones Cruzadas , Yodo , Fragmentos de Péptidos/inmunología , Péptidos/inmunología , Radioinmunoensayo , TripsinaRESUMEN
By use of the indirect immunofluorescence technique, the cellular localization of thyrotropin-releasing hormone (TRH) was studied in the gastrointestinal tract of rats and guinea pigs of different ages. TRH-like immunoreactivity (LI) was observed in many pancreatic islet cells of young rats and guinea pigs but only in single cells of 6-month-old rats. In aged guinea pigs, a reduction in the number of TRH-positive cells was evident; however, numerous strongly fluorescent cells were still present. In the guinea pig, TRH-LI was in addition observed in gastrin cells in the stomach. TRH-positive nerve fibers occurred in the myenteric plexus of the oesophagus, stomach and intestine of the rat, and in the muscle layers of the guinea pig. These results suggest a functional role of TRH both as hormone and neuroactive compound in various portions and sites of the gastro-intestinal tract of the rat and guinea pig.
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Sistema Digestivo/análisis , Glándulas Endocrinas/análisis , Islotes Pancreáticos/análisis , Estómago/análisis , Hormona Liberadora de Tirotropina/análisis , Animales , Sistema Digestivo/inervación , Cobayas , Inmunohistoquímica , Islotes Pancreáticos/metabolismo , Masculino , Ratas , Estómago/inervaciónRESUMEN
A new technique to obstruct the pancreatic ducts was developed by injecting zein solution into the common bile duct of the rat. Four weeks after the injection, the fate of the endocrine pancreas was investigated by studying (a) pancreatic content of four pancreatic hormones, (b) histology and immunohistochemistry of the pancreas, (c) i.v. glucose tolerance and i.v. insulin tolerance tests for monitoring plasma glucose, insulin, and pancreatic polypeptide (PP) levels in vivo, and (d) in vitro perifusion of pancreatic tissue slices to assess insulin and PP secretion. In zein-injected rats, the total pancreatic content of insulin, glucagon, PP, and somatostatin was reduced to 80, 70, 40, and 20%, respectively, of the corresponding controls. In response to insulin-induced hypoglycemia, the plasma PP levels rose to about one-half that of the controls. By contrast, perifused zein-injected rat pancreases released several times more PP than the controls in response to carbachol stimulation. In zein-injected rats, total pancreatic protein was reduced to 20% of the controls and pancreatic amylase was almost absent, reflecting practically complete loss of acinar tissue. Thus, this experimental model appears to be suitable for producing chronic pancreatic insufficiency in the rat and provides a useful model for studying both endocrine and exocrine functions in the small rodent.
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Insuficiencia Pancreática Exocrina/fisiopatología , Islotes Pancreáticos/fisiopatología , Animales , Modelos Animales de Enfermedad , Prueba de Tolerancia a la Glucosa , Técnicas In Vitro , Insulina/metabolismo , Secreción de Insulina , Masculino , Páncreas/patología , Polipéptido Pancreático/metabolismo , Ratas , Ratas Endogámicas , Zeína/farmacologíaRESUMEN
White Leghorn hens, 14 to 29 wk of age, were surgically prepared with cannulae for collecting secretions from the cystic duct and the duct draining the ventral pancreatic lobe and for infusing the jugular vein with avian pancreatic polypeptide (aPP) or saline. A plasma infusion rate that produced a plasma level of 15 ng of aPP/mL was used. A comparison of values obtained during saline infusion with those obtained during aPP infusion indicated that pancreatic and biliary secretory volumes and pancreatic total protein concentration were significantly depressed by aPP. The pH of pancreatic and biliary secretions were not significantly affected by aPP. Because aPP also depresses gastric secretion and motility in hens, it is proposed that its physiological role may be to oppose or modulate the actions of other, stimulatory gastrointestinal hormones.
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Bilis/metabolismo , Pollos/fisiología , Jugo Pancreático/metabolismo , Polipéptido Pancreático/farmacología , Animales , Bilis/efectos de los fármacos , Femenino , Jugo Pancreático/efectos de los fármacosRESUMEN
Oxyntomodulin, glucagon, and a glucagon-like peptide (GLP) have been isolated from the endocrine pancreas of the alligator gar (Lepisosteus spatula), a ganoid fish. The three peptides were isolated by gel filtration and HPLC and were identified by size, composition, and glucagon-like immunoreactivity. The amino acid sequences of the oxyntomodulin and GLP were determined. The oxyntomodulin contains 36 amino acid residues and its sequence is H S Q G T F T N D Y S K Y L D T R R A Q D F V Q W L M S T K R S G G I T. The composition of the glucagon is identical to the N-terminal 29 residues of the gar oxyntomodulin. The single form of GLP found contains 34 amino acid residues in the following sequence: H A D G T Y T S D V S S Y L Q D Q A A K K F V T W L K Q G Q D R R E. These findings suggest that all three peptides are derived from a common precursor.
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Peces/metabolismo , Hormonas Gastrointestinales/aislamiento & purificación , Péptidos Similares al Glucagón/aislamiento & purificación , Glucagón/aislamiento & purificación , Islotes Pancreáticos/análisis , Péptidos/aislamiento & purificación , Secuencia de Aminoácidos , Aminoácidos/análisis , Animales , Cromatografía en Gel , Cromatografía Líquida de Alta Presión , Femenino , Masculino , Datos de Secuencia Molecular , Oxintomodulina , RadioinmunoensayoRESUMEN
Reaction of avian pancreatic polypeptide with an iodine monochloride reagent at both pH 4 and pH 7.5 results in the differential modification of the four tyrosine residues in this peptide hormone. A total of 19 distinct iodinated derivatives were isolated by reverse-phase high-performance liquid chromatography, and their sites of iodination were characterized by both tryptic mapping and leucine aminopeptidase techniques coupled with HPLC. The pH 4 reaction produced 16 derivatives which, overall, represented substantial iodination at each tyrosine residue, whereas the pH 7.5 reaction was more directed, producing only 7 derivatives. Iodination at the C-terminal tyrosineamide 36 predominated at both pH values, and diiodo-Tyr 36 was found in the majority of the pH 7.5 derivatives. The relative of the four tyrosine residues with ICl were as follows: at pH 7.5, Tyr 36 much greater than Tyr 21 much greater than Tyr 27 greater than Tyr 7; at pH 4, Tyr 36 greater than Tyr 27 greater than Tyr 7 greater than Tyr 21.
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Yodo/análisis , Polipéptido Pancreático/análisis , Secuencia de Aminoácidos , Animales , Sitios de Unión , Aves , Cromatografía Líquida de Alta Presión , Concentración de Iones de Hidrógeno , Hidrólisis , Tripsina/farmacología , Pavos , Tirosina/análisisRESUMEN
Insulin and a 36-residue peptide with homology to pancreatic polypeptide (PP) were isolated from the endocrine pancreas of the alligator gar (Lepisosteus spatula), a ganoid fish, by gel filtration and HPLC. Heterologous radioimmunoassays were used to detect insulin-like and PP-like immunoreactivities during purification of the two peptides. The sequence of the 36-amino acid peptide containing a C-terminal tyrosinamide was identical at 31 of 36 positions to porcine neuropeptide Y (NPY). The amino acid sequence of this peptide is YPPKPENPGEDAPPEELAKYYSALRHYINLITRQRY-NH2. The second peptide, gar insulin, contains 52 amino acid residues and is composed of a 21-residue A chain and a 31-residue B chain. The sequence of the A chain is GIVEQCCHKPCTIYELENYCN. The sequence of the B chain is AANQHLCGSHLVEALYLVCGEKGFFYNPNKV.
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Peces/fisiología , Insulina/aislamiento & purificación , Islotes Pancreáticos/análisis , Polipéptido Pancreático/aislamiento & purificación , Secuencia de Aminoácidos , Animales , Sustancias Macromoleculares , Datos de Secuencia Molecular , Fragmentos de Péptidos/análisis , Homología de Secuencia de Ácido Nucleico , Especificidad de la EspecieRESUMEN
The amino acid sequence of a peptide isolated from the Pacific salmon (Oncorhynchus kisutch) endocrine pancreas has been determined. This simple 36 residue peptide is a member of the pancreatic polypeptide family. It contains a C-terminal tyrosinamide and is more homologous with porcine neuropeptide Y (NPY) (83%) and peptide YY (75%) than any of the previously characterized pancreatic polypeptides (PP). This peptide appears to be the major but not the only representative of this family of peptides present in the endocrine pancreas of this fish. This peptide is referred to as salmon pancreatic polypeptide (salmon PP).