RESUMEN
AIMS/HYPOTHESIS: Exendin-4 is a 39 amino acid agonist of the glucagon-like peptide receptor and has been approved for treatment of type 2 diabetes. Many reports describe an increased incidence of acute pancreatitis in humans treated with exendin-4 (exenatide). Previous studies have evaluated the effect of exendin-4 on beta cells and beta cell function. We evaluated the histological and biochemical effects of exendin-4 on the pancreas in rats. METHODS: We studied 20 Sprague-Dawley male rats, ten of which were treated with exendin-4 and ten of which were used as controls. The study period was 75 days. Serum and pancreatic tissue were removed for biochemical and histological study. Blood glucose, amylase, lipase, insulin and adipocytokines were compared between the two groups. RESULTS: Animals treated with exendin-4 had more pancreatic acinar inflammation, more pyknotic nuclei and weighed significantly less than control rats. They also had higher serum lipase than control animals. Exendin-4 treatment was associated with lower insulin and leptin levels as well as lower HOMA values than in the untreated control group. CONCLUSIONS/INTERPRETATION: Although the use of exendin-4 in rats is associated with decreased weight gain, lower insulin resistance and lower leptin levels than in control animals, extended use of exendin-4 in rats leads to pancreatic acinar inflammation and pyknosis. This raises important concerns about the likelihood of inducing acute pancreatitis in humans receiving incretin mimetic therapy.
Asunto(s)
Hipoglucemiantes/farmacología , Páncreas/metabolismo , Péptidos/farmacología , Ponzoñas/farmacología , Adipoquinas/sangre , Alanina Transaminasa/sangre , Amilasas/sangre , Amilasas/efectos de los fármacos , Animales , Aspartato Aminotransferasas/sangre , Glucemia/efectos de los fármacos , Glucemia/metabolismo , Peso Corporal/efectos de los fármacos , Exenatida , Humanos , Insulina/sangre , Lipasa/sangre , Lipasa/efectos de los fármacos , Masculino , Páncreas/citología , Páncreas/efectos de los fármacos , Páncreas/patología , Pancreatitis/inducido químicamente , Pancreatitis/patología , Ratas , Ratas Sprague-DawleyRESUMEN
Both hypobaric exposure at 0.5 atmospheres absolute (ATA) and hyperbaric pressure exposure at 3.5-8 ATA slowed transplantable tumor growth. These experiments detailed the hyperbaric pressure exposure. C3H/HeN-MTV+ mice, bearing the 16/C transplantable murine mammary adenocarcinoma and exposed to 18 days' treatment by a hyperbaric chamber at 3.5-8 ATA, had tumor weights that averaged 50-75% less than the tumor weights in mice caged at ambient ("sea level") pressure. A series of experiments was run to investigate this response to hyperbaric pressure exposure. After mice underwent continuous exposure to 3.5-8 ATA normoxic (normal oxygen) hyperbaric pressure with use of either argon or nitrogen inert gas, which began 3 days after tumor inoculation, tumors were removed at about 3 weeks' growth from these pressure-exposed mice and measured for growth by weighing. Final tumor weight in pressure-exposed experimental mice was significantly less than tumor weight in paired groups of tumor-bearing controls that received no hyperbaric pressure. Tumor weight was inversely related to pressure "dose," although the small pressure range produced an effect at all pressures used. The number of compression-decompression cycles to which the animals were subjected, however, was related positively to tumor weight at necropsy. Continued tumor growth in mice subjected to frequent pressure change (in conjunction with pressure exposure that otherwise limited tumor size) was unexplained by these experiments. The greatest difference between tumor weights in controls and pressure-exposed animals was seen with 2 weeks' continuous pressure exposure. A limited profile of blood tests was performed, and these reflected only minor, expected change in the pressure-exposed experimental animals. The data at hand did not suggest a mechanism by which chronic normoxic hyperbaric pressure limited tumor size.
Asunto(s)
Adenocarcinoma/patología , Presión Atmosférica , Oxigenoterapia Hiperbárica , Neoplasias Mamarias Experimentales/patología , Animales , Peso Corporal , División Celular , Femenino , Oxigenoterapia Hiperbárica/instrumentación , Ratones , Ratones Endogámicos , Nitrógeno , Tamaño de los ÓrganosRESUMEN
Inasmuch as solid tumor growth and some intervention methods for tumor control have often been related to the low oxygen levels in tumor tissue, and a special role for hypoxia, perhaps even in oncogenesis, has been suggested by observations of unexpectedly low tumor incidence in mice caged a lifetime in the environment of a simulated altitude, inbred C3H/HeN mammary tumor virus-positive mice bearing transplanted tumors (16/C murine mammary adenocarcinoma) were exposed to atmospheric pressure variants ranging from 0.33 to 2.0 in different sequences 24 hours/day. Breathing gases included air, 100% oxygen, and other nitrogen--oxygen combinations. Exposure to the pressure sequences was continuous, beginning on the third day after tumor inoculation and continuing until planned necropsy at 1, 2, or 3 weeks. Actual tumor weight was used as a measure of effect. Mice caged at simulated altitude had tumors that averaged 45% of the weight of control tumors. The maximum effect occurred with continuous 2-week exposure to 0.43 atm. beginning on day 3 of tumor growth. At necropsy, these experimental tumors weighed an average of 15% of the control tumor weight. Life-span studies showed a maximum of 36% increase in longevity in the hypobaric pressure-exposed mice when compared to that of unexposed controls.
Asunto(s)
Adenocarcinoma/fisiopatología , Neoplasias Mamarias Experimentales/fisiopatología , Presión , Anaerobiosis , Animales , División Celular , Femenino , Neoplasias Mamarias Experimentales/microbiología , Virus del Tumor Mamario del Ratón/aislamiento & purificación , Ratones , Ratones Endogámicos , Índice MitóticoRESUMEN
Male Syrian hamsters fed a commercial diet were given a series of 12 intratracheal instillations of 3 mg benzo (alpha) pyrene adherent to 3 mg Fe2O3 in 0.2 ml 0.15 M NaCl at weekly intervals. After the last instillation, the hamsters were randomly assigned to receive either 100, 1600, or 3300 (later reduced to 2400) mug retinyl acetate per week in divided intragastric doses. Hamsters in the 2400-mug retinyl acetate group had a significantly higher incidence of respiratory tract tumors than those in the group given 100 mug retinyl acetate per week. Liver vitamin A stores increased dramatically in the groups given 1600 and 2400 mug retinyl acetate and corresponded to the administration of retinyl acetate p.o. Serum vitamin A values were not consistently related to retinyl acetate administration or to hepatic stores of vitamin A.
Asunto(s)
Benzopirenos , Carcinógenos , Carcinoma/inducido químicamente , Neoplasias Glandulares y Epiteliales/inducido químicamente , Neoplasias del Sistema Respiratorio/inducido químicamente , Sarcoma/inducido químicamente , Vitamina A/toxicidad , Adenocarcinoma/inducido químicamente , Adenoma/inducido químicamente , Animales , Carcinoma de Células Escamosas/inducido químicamente , Carcinosarcoma/inducido químicamente , Cricetinae , Dieta , Sinergismo Farmacológico , Fibrosarcoma/inducido químicamente , Hiperplasia/inducido químicamente , Intubación Intratraqueal , Hígado/análisis , Masculino , Metaplasia/inducido químicamente , Neoplasias Experimentales/inducido químicamente , Papiloma/inducido químicamente , Sarcoma Experimental/inducido químicamente , Vitamina A/análisis , Vitamina A/sangreRESUMEN
Identification and assessment of cell populations in bronchoalveolar lavage (BAL) specimens may he used to follow the course of a disease state or response to specific therapy. Beyond cellular assessment, there are indications that the presence and quantity of soluble surface antigens released from activated cells may lead to improved understanding and facilitated diagnosis of a number of disease states. This study evaluated soluble markers (sCD4 and sCD8) in BAL and serum from HIV-infected individuals undergoing diagnostic bronchoscopy, and compared these values to flow cytometry-quantified BAL and peripheral blood cell CD4 and CD8. Patient pulmonary diagnosis (based on cytology and microbiology) was compared with patient blood and BAL-soluble and cell-bound CD4 and CD8 to determine the relationship of these markers to disease states in this population. Serum sCD8 in patients with fungal infections was significantly elevated above sCD8 in patients with Pneumocystis carinii or pulmonary bacterial infections, p = 0.0001. BAL sCD4/sCD8 ratio was also significantly different in patients with bacterial vs. fungal pulmonary infections, p = 0.01. These findings suggest that soluble markers, particularly elevated sCD8, may be an important indication of pulmonary disease progression in these HIV+ patients with fungal infections.
Asunto(s)
Líquido del Lavado Bronquioalveolar/química , Antígenos CD4/análisis , Antígenos CD8/análisis , Infecciones por VIH/inmunología , Relación CD4-CD8 , Femenino , Citometría de Flujo , Humanos , Masculino , Neumonía por Pneumocystis/inmunologíaRESUMEN
We correlated quantity of streptococcal polysaccharides and endocarditis production by those bacterial strains. To investigate this finding further, we studied the composition of the glycocalyx using a spectrophotometric assay and lectin analysis of exopolysaccharides from endocarditis- and non-endocarditis-producing strains of viridans streptococci. Identical weights of glycocalyx from the clinical endocarditis isolates produced significantly different absorbances as compared with the nonendocarditis isolates (P < 0.0012, Wilcoxon rank test). Lectin-binding experiments showed that endocarditis-producing streptococci contained increased amounts of glucose, galactose, sialic acid, and mannose. These data suggest that the glycocalyx of endocarditis-producing viridans streptococci is both qualitatively and quantitatively different from non-endocarditis-producing isolates. These differences can be measured in vitro.
Asunto(s)
Endocarditis Bacteriana/microbiología , Glicoproteínas/química , Hexosas/análisis , Polisacáridos/química , Streptococcus/química , Glicoproteínas/aislamiento & purificación , Hexosas/metabolismo , Humanos , Lectinas/metabolismo , Polisacáridos/aislamiento & purificación , Streptococcus/clasificaciónRESUMEN
BACKGROUND: Management of recurrent spontaneous pneumothorax or symptomatic pleural effusion often uses thoracoscopic pleurodesis, about which many questions remain. Both effectiveness and toxicity of agents currently used for pleurodesis were evaluated in a rabbit model. METHODS: Agents administered were autologous blood 1 mL/kg, talc slurry (70 mg x mL(-1) x kg(-1)), and doxycycline 10 mg/mL, given through a chest tube to 30 rabbits. Controls had only chest tubes inserted. At 30 days surfaces were graded by gross observation and histologic examination. Blood and lung tissue from all animals were analyzed for enzymes and blood chemistries. RESULTS: Gross observations showed mediastinal thickening and adhesions with doxycycline, and threadlike adhesions with talc. Autologous blood was only slightly more effective than a chest tube alone. Talc significantly increased angiotensin converting enzyme activity in serum, whereas doxycycline changed liver function enzymes and produced tissue toxicity. CONCLUSIONS: Doxycycline produced effective pleurodesis but yielded remarkably severe local effects. The distant sequelae of talc and doxycycline pleurodesis-histologic changes in the contralateral lung and serum enzyme elevations-suggests undesirable systemic effects for the commonly used agents, and autologous blood exhibited no significant pleurodesis, short-term. The search for the ideal agent for chemical pleurodesis continues.
Asunto(s)
Antibacterianos/farmacología , Sangre , Doxiciclina/farmacología , Pleurodesia/métodos , Talco/farmacología , Animales , Antibacterianos/administración & dosificación , Doxiciclina/administración & dosificación , Femenino , Pleura/patología , Pleurodesia/efectos adversos , Conejos , Talco/efectos adversosRESUMEN
OBJECTIVE: Staphylococcus epidermidis adherence to indwelling polymers is important in prosthetic valve endocarditis. Earlier studies have related streptococcal endocarditis to isolates with high levels of cell-associated hexoses. The objective of the present study was to determine if a relationship exists between an S epidermidis isolate assay score and production/severity of experimental endocarditis. DESIGN: Groups of patient S epidermidis isolates were screened for surface hexoses and an animal model of endocarditis with isolates testing highest and lowest on the screen was produced. Disease severity produced by 'high hexose' versus 'low hexose' organisms was evaluated. Endocarditis responding variables were bacterial vegetation weight and log(10) colony forming units (cfu) and in survival tests, comparative time to death with different isolates. Bacterial characteristics were not measured. Baseline data showed a vegetation weight difference so that with a ß error of 0.20 and a two-tailed α error of 0.05, a significant difference would be noted using 30 animals. A total of 64 animals was used. POPULATION STUDDED: Bacterial isolates from two patient groups (n=42 and n=68) on which in vitro assays were run. An animal model of endocarditis (n=64) was used to evaluate four selected isolates for vegetation size, log(10) cfu/g, and survival time. MAIN RESULTS: In a group of S epidermidis endocarditis animals evaluated for time of death, a significantly more rapid death time resulted in the group dosed with the high hexose-scoring organism (P<0.025). Vegetations and log(10) cfu produced by test high hexose isolates averaged larger but were not significantly different. CONCLUSIONS: A significantly more rapid death rate occurs in untreated endocarditis using a high hexose isolate than with S epidermidis with low surface hexoses. Using bacterial vegetation and cfu as endpoints, however, experimental endocarditis using patient isolates of S epidermidis does not show the same strong correlation to bacterial surface hexoses as does streptococcal endocarditis.
RESUMEN
OBJECTIVE: To evaluate the importance of thrombocytopenia in streptococcal endocarditis using an animal model. DESIGN: A model of human septic endocarditis was established in rats (polyethylene catheters across the aortic valve and administration of Streptococcus sanguis, 5×10(7) colony forming units [cfu] intravenous). Thrombocytopenia at four levels was produced by antiplatelet serum. Secondary methods of producing thrombocytopenia were also evaluated. At sacrifice (96 h after platelet depletion and 72 h after infection), vegetations were removed, weighed, diluted, plated and counted. Potential mechanisms of the dose-response relationship between vegetation density and platelet count were evaluated. SETTING: Controlled research laboratory experiments. POPULATION STUDIED: Animal models of streptococcal endocarditis. MAIN RESULTS: The bacterial density of the aortic valve vegetations significantly increased as the platelet count decreased (P=0.0007). In severely thrombocytopenic animals (two-dose antiplatelet serum), data suggest increased vegetation embolism. Platelet depletion, which was minimal with chemical methods, was produced most effectively by antithrombocyte serum. Platelet surfaces in endocarditis were found to express elevated CD62p proteins (72.7% endocarditis, 34.7% control). Platelet protein fractions were evaluated in vitro by both streptocidal (P=0.19) and phagocytosis-stimulating assays. Platelet presence in mature aortic valve vegetations averaged only about 2%. CONCLUSIONS: In platelet depletion experiments using a rat model, a dose-response relationship of peripheral circulating platelet depletion to aortic valve vegetation density was found. The mechanism relating thrombocytopenia to endocarditis severity remains unresolved.
RESUMEN
It is well recognized that the administration of beta blockers to patients after myocardial infarction improves survival. This retrospective cohort and prospective study sought to define the usage of a large hospitalist group and enhance this usage by education and the utilization of a uniform discharge summary. All patients with a discharge diagnosis of acute myocardial infarction were included for analysis. The use of beta blockers by the hospitalist group was initially collected retrospectively and compared with two large cohorts. The data were presented to the hospitalist group. Prospective data collection then commenced. Retrospective analysis of the use of beta blockers showed a rate of 68% as compared with 21% and 34% in two large cohorts (P < .0001). After data were reviewed and conference occurred, prospective use of beta blockers increased to 90% (P < .0005). Patients with myocardial infarction were extremely likely to be treated with beta blockers by this hospitalist group. Review of previous usage and review of contraindications along with the use of a uniform discharge summary resulted in a significant increase in the use of these life-saving drugs.
Asunto(s)
Antagonistas Adrenérgicos beta/uso terapéutico , Utilización de Medicamentos/estadística & datos numéricos , Médicos Hospitalarios/estadística & datos numéricos , Infarto del Miocardio/tratamiento farmacológico , Pautas de la Práctica en Medicina , Anciano , Anciano de 80 o más Años , Estudios de Cohortes , Contraindicaciones , Femenino , Humanos , Masculino , Missouri/epidemiología , Infarto del Miocardio/mortalidad , Estudios Prospectivos , Estudios RetrospectivosRESUMEN
BACKGROUND: The objective of this study was to assess the value of intercellular adhesion molecule-1 (ICAM-1) levels in bronchoalveolar lavage (BAL) specimens. METHODS: BALs from 44 unselected patients undergoing routine diagnostic bronchoscopy with bronchoalveolar lavage were studied. Cell-free supernatants of the BAL specimens were frozen at -70 degrees C until tested. BAL ICAM-1 concentration was measured using enzyme immunoassay and degree of patient illness assessed by modified APACHE II scores. RESULTS: ICAM-1 in BAL fluid was positively correlated to the patient illness score (modified APACHE II) at a p value of 0.026. No such association was found between ICAM-1 levels and cigarette use or infection with pneumocystis carinii, although a few individuals in the smoker's group with pulmonary infection had 10-fold elevations of BAL ICAM-1. CONCLUSIONS: BAL ICAM-1 may relate to the pulmonary pathogenic process as supported by the association between modified APACHE II scores and ICAM-1 values. Specific pulmonary-related diagnosis and BAL ICAM-1 did not produce significant relationships in this study.
Asunto(s)
Líquido del Lavado Bronquioalveolar/química , Molécula 1 de Adhesión Intercelular/análisis , Neumonía Bacteriana/diagnóstico , Neumonía por Pneumocystis/diagnóstico , APACHE , Humanos , Proyectos Piloto , Fumar/efectos adversosRESUMEN
Pulmonary sarcoidosis, a human disease of unknown cause, has no animal model. Sarcoidosis patients have serum antibodies specific for Helicobacter pylori and its surface enzyme urease. H. pylori do not survive in the high-oxygen pulmonary atmosphere, but urease may access the lung by oesophageal reflux. A model was established in rats to study gastro-oesophageal reflux of urease into the airways. Pathology in tissues from human sarcoidosis patients was compared with that in the rat model. Changes observed in the rat model included prominent peribronchial lymphocytic infiltration, which is seen occasionally in human sarcoidosis. Granulomas, pathognomonic for human sarcoidosis, occurred occasionally in the lungs of rats given urease protein intratracheally, but were widespread when urease was coupled to microbeads and administered intravenously. Biomarkers associated with human sarcoidosis (interleukin1-ß and platelet-activating factor) were up-regulated acutely in the rat model. Further investigations with this model may provide significant insights into the origin and pathogenesis of pulmonary diseases in man and other species that carry gastric Helicobacter spp. and its associated enzyme.
Asunto(s)
Antígenos Bacterianos/sangre , Modelos Animales de Enfermedad , Granuloma/inmunología , Helicobacter pylori/inmunología , Enfermedades Pulmonares/inmunología , Sarcoidosis Pulmonar/inmunología , Ureasa/inmunología , Administración Oral , Adulto , Animales , Femenino , Reflujo Gastroesofágico/complicaciones , Granuloma/metabolismo , Granuloma/patología , Humanos , Interleucina-1beta/metabolismo , Pulmón/metabolismo , Pulmón/patología , Enfermedades Pulmonares/metabolismo , Enfermedades Pulmonares/patología , Linfocitos/patología , Masculino , Persona de Mediana Edad , Factor de Activación Plaquetaria/metabolismo , Ratas , Ratas Sprague-Dawley , Sarcoidosis Pulmonar/metabolismo , Sarcoidosis Pulmonar/patología , Ureasa/administración & dosificaciónAsunto(s)
Hidrazinas , Neoplasias Intestinales/inducido químicamente , Deficiencia de Vitamina A/complicaciones , Adenocarcinoma/inducido químicamente , Animales , Dieta , Interacciones Farmacológicas , Hidrazinas/administración & dosificación , Mucosa Intestinal , Neoplasias Intestinales/complicaciones , Metabolismo de los Lípidos , Hígado/metabolismo , Masculino , Metástasis de la Neoplasia , Ratas , Ratas Endogámicas , Factores de Tiempo , Vitamina A/administración & dosificación , Vitamina A/efectos adversos , Vitamina A/sangre , Vitamina A/metabolismoRESUMEN
A quantitative method to determine glycocalyx production by strains of viridans group streptococci from patients with endocarditis is presented. There is good correlation between this new tryptophan quantitative assay and qualitative assays employing polysaccharide stains (ruthenium red, periodic acid-Schiff, and Cellufluor) or the Molisch test. The quantification of the glycocalyx production in glucose substrate in vitro by viridans group streptococci correlates with the size of cardiac vegetation and ease of antimicrobial sterilization in experimental endocarditis. The relationship of in vitro quantification of glycocalyx to maintenance of infection, morbidity of infection, and antimicrobial treatment is discussed.
Asunto(s)
Endocarditis Bacteriana/microbiología , Glicoproteínas/análisis , Polisacáridos/análisis , Infecciones Estreptocócicas/microbiología , Streptococcus/metabolismo , Animales , Modelos Animales de Enfermedad , Glicoproteínas/biosíntesis , Humanos , Polisacáridos/biosíntesis , Conejos , Coloración y Etiquetado , TriptófanoRESUMEN
Bacteria persist within abscesses despite the presence of neutrophils, and patients with abscesses have high rates of subsequent infections. A model was developed to study neutrophil function in rabbits with Staphylococcus aureus abscesses. Blood neutrophils from rabbits with 2-week-old (chronic) abscesses had diminished bactericidal capacity and decreased superoxide production compared with rabbits with 24-h (acute) abscesses. Rabbits with chronic abscesses did not produce serum opsonic factors that enhanced bacterial killing. A bactericidal assay performed with chronic abscess fluid in the suspending medium revealed inhibition of neutrophil killing. The inhibition could be replicated with a neutrophil lysate but not by an S. aureus supernatant. Rabbits with chronic abscesses have diminished blood neutrophil bactericidal capacity and superoxide formation, and the abscess fluid milieu is inhibitory to neutrophil function.
Asunto(s)
Absceso/inmunología , Actividad Bactericida de la Sangre , Neutrófilos/inmunología , Infecciones Estafilocócicas/inmunología , Staphylococcus aureus/inmunología , Enfermedad Aguda , Animales , Enfermedad Crónica , Modelos Animales de Enfermedad , Proteínas Opsoninas/biosíntesis , Proteínas Opsoninas/inmunología , Fagocitosis/inmunología , ConejosRESUMEN
To assess the role of glycocalyx production in the pathogenesis of endocarditis caused by viridans group streptococci in adult patients, glycocalyx production was examined for 49 blood culture isolates. The tryptophan assay, a quantitative spectrophotometric test, was used to measure cell-adherent glycocalyx production. Absorbance values of the isolates that produced endocarditis were significantly higher (means, 0.166 versus 0.060 [P less than 0.001]). At a breakpoint of absorbance of 0.120, the sensitivity of the test was 0.83, the specificity was 0.96, and the predictive value was 0.95. These data suggest that the in vitro tryptophan assay of glycocalyx production by viridans group streptococci has potential value as a predictor of clinical pathogenicity.