RESUMEN
This paper compares Petrifilm™ aerobic count (AC) plates to drop plating on R2A agar plates as an alternative method for biofilm bacteria enumeration after application of a disinfectant. A Pseudomonas aeruginosa biofilm was grown in a Centers for Disease Control and Prevention biofilm reactor (ASTM E2562) and treated with 123 ppm sodium hypochlorite (as free chlorine) according to the Single Tube Method (ASTM E2871). Aliquots from the same dilution tubes were plated on Petrifilm™ AC plates and drop plated on R2A agar plates. The Petrifilm™ AC and R2A plates were incubated for 48 and 24 h, respectively, at 36 ± 1 °C. After nine experimental runs performed by two technicians, the mean difference in biofilm log densities [log biofilm density (LD) = log10(CFU/cm(2))] between the two methods for control coupons, treated coupons, and log reduction (LR) was 0.052 (p = 0.451), -0.102 (p = 0.303), and 0.152 (p = 0.313). Equivalence testing was used to assess equivalence of the two plating methods. The 90 % confidence intervals for the difference in control and treated mean LDs between methods were (-0.065, 0.170) and (-0.270, 0.064), both of which fall within a (-0.5, +0.5) equivalence criterion. The 90 % confidence interval for the mean LR difference (-0.113, 0.420) also falls within this equivalence criterion. Thus, Petrifilm™ AC plates were shown to be statistically equivalent to drop plating on R2A agar for the determination of control LDs, treated LDs, and LR values in an anti-biofilm efficacy test. These are the first published results that establish equivalency to a traditional plate counting technique for biofilms and for a disinfectant assay.
Asunto(s)
Bacterias/efectos de los fármacos , Bacterias/crecimiento & desarrollo , Biopelículas , Desinfectantes/farmacología , Pruebas de Sensibilidad Microbiana , Recuento de Colonia Microbiana , Pseudomonas aeruginosa/efectos de los fármacos , Pseudomonas aeruginosa/crecimiento & desarrolloRESUMEN
Obesity rates have steadily increased over the past two decades. To address the epidemic in women, the Health Resources and Services Administration's Maternal and Child Health Bureau, Division of Healthy Start and Perinatal Services (HRSA/MCHB/DHSPS) awarded 14 demonstration grants to community health centers, health departments, universities and community-based organizations in 12 states to develop innovative approaches aimed at reducing the prevalence of overweight and obesity, specifically in women of childbearing age. Grantees implemented modified or existing evidence-based programs (EBP) or promising practices tailored to the geographic locations, cultures and traditional values of the communities. A review of the 15 programs implemented from 2004 to 2007 was conducted using the methodology outlined in the Transparent Reporting of Evaluations with Nonrandomized Designs Statement to identify indicators of successful program implementation. The six indicators identified were: (1) supportive organizational culture with adequate resources and appropriate staff; (2) attention to the needs of the service population; (3) a referral system that links participants to appropriate services; (4) flexible schedules; (5) support for child care and transportation; and (6) formal and informal support systems to keep participants engaged and motivated. Two of the programs that reported improved participant outcomes are available for replication: La Vida Sana, La Vida Feliz in Illinois was designated as a promising practice by the Association of Maternal and Child Health Programs and Sisters in Action in Michigan was rated as a moderate evidence-based program by the Agency for Healthcare Research and Quality.
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Práctica Clínica Basada en la Evidencia/métodos , Servicios de Salud Materna , Obesidad/prevención & control , Evaluación de Procesos y Resultados en Atención de Salud , Vigilancia de la Población/métodos , Evaluación de Programas y Proyectos de Salud/métodos , Peso Corporal , Femenino , Humanos , Innovación Organizacional , EmbarazoRESUMEN
The MBEC™ Physiology & Genetics Assay recently became the first approved ASTM standardized biofilm disinfectant efficacy test method. This report summarizes the results of the standardization process using Pseudomonas aeruginosa biofilms. Initial ruggedness testing of the MBEC method suggests that the assay is rugged (i.e., insensitive) to small changes to the protocol with respect to 4 factors: incubation time of the bacteria (when varied from 16 to 18h), treatment temperature (20-24°C), sonication duration (25-35min), and sonication power (130-480W). In order to assess the repeatability of MBEC results across multiple tests in the same laboratory and the reproducibility across multiple labs, an 8-lab study was conducted in which 8 concentrations of each of 3 disinfectants (a non-chlorine oxidizer, a phenolic, and a quaternary ammonium compound) were applied to biofilms using the MBEC method. The repeatability and reproducibility of the untreated control biofilms were acceptable, as indicated by small repeatability and reproducibility standard deviations (SD) (0.33 and 0.67 log10(CFU/mm(2)), respectively). The repeatability SDs of the biofilm log reductions after application of the 24 concentration and disinfectant combinations ranged from 0.22 to 1.61, and the reproducibility SDs ranged from 0.27 to 1.70. In addition, for each of the 3 disinfectant types considered, the assay was statistically significantly responsive to the increasing treatment concentrations.
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Biopelículas/efectos de los fármacos , Desinfectantes/farmacología , Pseudomonas aeruginosa/efectos de los fármacos , Pseudomonas aeruginosa/fisiología , Concentración de Iones de Hidrógeno , Pruebas de Sensibilidad Microbiana/métodos , Reproducibilidad de los Resultados , Sonicación , Temperatura , Factores de TiempoRESUMEN
Increasing amino acid availability (via infusion or ingestion) at rest or postexercise enhances amino acid transport into human skeletal muscle. It is unknown whether alterations in amino acid availability, from ingesting different dietary proteins, can enhance amino acid transport rates and amino acid transporter (AAT) mRNA expression. We hypothesized that the prolonged hyperaminoacidemia from ingesting a blend of proteins with different digestion rates postexercise would enhance amino acid transport into muscle and AAT expression compared with the ingestion of a rapidly digested protein. In a double-blind, randomized clinical trial, we studied 16 young adults at rest and after acute resistance exercise coupled with postexercise (1 h) ingestion of either a (soy-dairy) protein blend or whey protein. Phenylalanine net balance and transport rate into skeletal muscle were measured using stable isotopic methods in combination with femoral arteriovenous blood sampling and muscle biopsies obtained at rest and 3 and 5 h postexercise. Phenylalanine transport into muscle and mRNA expression of select AATs [system L amino acid transporter 1/solute-linked carrier (SLC) 7A5, CD98/SLC3A2, system A amino acid transporter 2/SLC38A2, proton-assisted amino acid transporter 1/SLC36A1, cationic amino acid transporter 1/SLC7A1] increased to a similar extent in both groups (P < 0.05). However, the ingestion of the protein blend resulted in a prolonged and positive net phenylalanine balance during postexercise recovery compared with whey protein (P < 0.05). Postexercise myofibrillar protein synthesis increased similarly between groups. We conclude that, while both protein sources enhanced postexercise AAT expression, transport into muscle, and myofibrillar protein synthesis, postexercise ingestion of a protein blend results in a slightly prolonged net amino acid balance across the leg compared with whey protein.
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Sistemas de Transporte de Aminoácidos/biosíntesis , Aminoácidos/metabolismo , Proteínas en la Dieta/administración & dosificación , Proteínas de la Leche/administración & dosificación , Músculo Esquelético/fisiología , Entrenamiento de Fuerza/métodos , Proteínas de Soja/administración & dosificación , Administración Oral , Adulto , Sistemas de Transporte de Aminoácidos/efectos de los fármacos , Aminoácidos/efectos de los fármacos , Proteínas en la Dieta/metabolismo , Método Doble Ciego , Ingestión de Alimentos/fisiología , Femenino , Humanos , Masculino , Músculo Esquelético/efectos de los fármacos , Proteínas de Soja/farmacocinética , Regulación hacia Arriba/efectos de los fármacos , Regulación hacia Arriba/fisiología , Proteína de Suero de Leche , Adulto JovenRESUMEN
Satellite cells are a heterogeneous population of myogenic precursors responsible for muscle growth and repair in mammals. The objectives of the experiment were to examine the growth rates and degree of heterogeneity within bovine satellite cells (BSC) isolated from young and adult animals. The BSC were harvested from the semimembranosus of young (4.3 ± 0.5 d) and adult (estimated 24 to 27 mo) cattle and cultured en masse. Young animal BSC re-enter the cell cycle sooner and reach maximal 5-ethynyl-2'-deoxyuridine (EdU) incorporation earlier (P < 0.05) than adult contemporaries. Adult BSC contain fewer (P < 0.05) MyoD and myogenin immunopositive nuclei than BSC isolated from young animals after 3, 4, and 5 d in culture. These results indicate that BSC from young animals activate, proliferate, and differentiate sooner than isolates from adult animals. Lineage heterogeneity within BSC was examined using antibodies specific for Pax7 and Myf5, lineage markers of satellite cells, and myoblasts. Immunocytochemistry revealed the majority of Pax7-expressing BSC also express Myf5; a minor population (~5%) fails to exhibit Myf5 immunoreactivity. The percentage of Pax7:Myf5 BSC from young animals decreases sooner (P < 0.05) in culture than adult BSC, indicating a more rapid rate of muscle fiber formation. A subpopulation immunopositive for Myf5 only was identified in both ages of BSC isolates. The growth kinetics and heterogeneity of young BSC was further evaluated by clonal analysis. Single cell clones were established and analyzed after 10 d. Colonies segregated into 2 groups based upon population doubling time. Immunostaining of the slow-growing colonies (population doubling time ≥ 3 d) revealed that a portion exhibited asymmetric distribution of the lineage markers Pax7 and Myf5, similar to self-renewable mouse muscle stem cells. In summary, these results offer insight into the heterogeneity of BSC and provide evidence for subtle differences between rodent and bovine myogenic precursors.
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Envejecimiento/fisiología , Bovinos/fisiología , Células Satélite del Músculo Esquelético/citología , Células Satélite del Músculo Esquelético/fisiología , Animales , Células Cultivadas , Femenino , MasculinoRESUMEN
We evaluated growth-related responses to ractopamine in steers and heifers. Sixteen Angus steers (512 kg) and 16 Angus heifers (473 kg) housed in individual pens were used in a complete block design. At 90 to 97 d before the experiment, steers were implanted with 120 mg of trenbolone acetate and 24 mg of estradiol-17beta (Component TE-S) and heifers were implanted with 140 mg of trenbolone acetate and 14 mg of estradiol-17beta (Component TE-H). Treatments were arranged as a 2 x 2 factorial and included sex (steer vs. heifer) and ractopamine-HCl (0 or 200 mg/d). Cattle were fed a diet based on steam-flaked corn once daily. Blood and LM and biceps femoris (BF) biopsy samples were collected on d 0 (before ractopamine feeding) and after 14 and 28 d of ractopamine feeding. Serum insulin concentrations were not affected by ractopamine or sex. Serum IGF-I concentrations were greater in steers than heifers (P < 0.001), and steers demonstrated greater IGF-I mRNA expression in BF than heifers (P = 0.05). Ractopamine decreased serum IGF-I concentrations in heifers on d 14, but increased serum IGF-I concentrations in steers on d 28 (sex x ractopamine x day interaction; P = 0.03). Ractopamine did not affect (P >or= 0.19) mRNA expression of IGF-I, IGFBP-3, or calpastatin in BF or LM. However, ractopamine led to increases in LM expression of IGFBP-5 in heifers, but to decreases in expression in steers (ractopamine x sex interaction; P = 0.04). Ractopamine decreased myosin heavy chain IIA mRNA expression in BF (P = 0.04) but not in LM (P = 0.99). Ractopamine decreased beta(2)-receptor mRNA expression in LM of steers on d 14, but not on d 28; in contrast, expression of beta(2)-receptor mRNA in LM of heifers was not affected by ractopamine (sex x ractopamine x day interaction; P = 0.03). Although there were a few criteria for which ractopamine led to differences in response between steers and heifers, there were no striking disparities to suggest that the effectiveness of ractopamine would markedly differ between sexes.
Asunto(s)
Bovinos/crecimiento & desarrollo , Sustancias de Crecimiento/farmacología , Músculo Esquelético/efectos de los fármacos , Fenetilaminas/farmacología , Animales , Proteínas de Unión al Calcio/sangre , Bovinos/sangre , Femenino , Expresión Génica/efectos de los fármacos , Insulina/sangre , Proteína 3 de Unión a Factor de Crecimiento Similar a la Insulina/sangre , Factor I del Crecimiento Similar a la Insulina/análisis , Masculino , Músculo Esquelético/crecimiento & desarrollo , Músculo Esquelético/metabolismo , Reacción en Cadena de la Polimerasa , Factores SexualesRESUMEN
Toxicokinetic data have traditionally been presented as maximum observed plasma concentrations (C(max)) and area under the concentration time curve (AUC) values. These values have been used to compare exposures across studies and species to provide valuable interpretation of drug safety data. Increasingly, questions are asked of toxicology studies to more accurately describe the concentration effect relationships in terms of compound affinity for target and off-target receptors. C(max) values can immediately be referenced to known pharmacological activities, particularly when the extent of plasma protein binding is taken into account. This provides a measure of the more pharmacologically relevant free drug exposure. AUC values on the other hand contain the component of time, which means that direct comparison to pharmacological activity values are not immediately possible. Conversion of AUC to average plasma concentration (C(av)) provides a simple and convenient means to allow such a comparison without losing any information imparted by AUC values. In this paper, the benefit and advantage of applying C(av) values is illustrated using examples taken from the literature.
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Seguridad de Productos para el Consumidor , Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos , Farmacocinética , Pruebas de Toxicidad/métodos , Animales , Área Bajo la Curva , Relación Dosis-Respuesta a Droga , Humanos , Preparaciones Farmacéuticas/administración & dosificación , Factores de TiempoRESUMEN
The requirements for safe testing of pharmaceuticals in humans places substantial emphasis on the translation of safety testing performed in animals to man. The comparison of systemic exposure in animals and man has taken on increasing importance in this assessment, with the underlying assumption that plasma concentrations will elicit the same response in different species. This assumption may be flawed for a number of different reasons, one of which is differences in drug disposition between species leading to high doses required in animal species to yield equivalent systemic exposure to humans and consequent higher exposure to organs such as the intestine and liver. Hepatic clearance can vary substantially, particularly between rodents and man, resulting in vast differences in the dose-exposure relationship. A specific example of a non-nucleoside reverse transcriptase inhibitor, which causes substantial auto-induction in rodents, is used to illustrate this situation and the impact this has on the interpretation of safety extrapolation from animals to man. In such circumstances, it is important to recognize the impact of species differences in drug clearance and disposition and consider broader input in the assessment of clinical safety.
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Nitrilos/farmacocinética , Pirazoles/farmacocinética , Inhibidores de la Transcriptasa Inversa/farmacocinética , Adolescente , Adulto , Animales , Perros , Relación Dosis-Respuesta a Droga , Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos , Femenino , Humanos , Mucosa Intestinal/metabolismo , Hígado/metabolismo , Masculino , Ratones , Persona de Mediana Edad , Nitrilos/administración & dosificación , Pirazoles/administración & dosificación , Ratas , Ratas Sprague-Dawley , Inhibidores de la Transcriptasa Inversa/administración & dosificación , Especificidad de la EspecieRESUMEN
Skeletal muscle growth is accomplished chiefly through the actions of satellite cells, a heterogeneous population that includes the adult muscle stem cell. Located adjacent to a mature muscle fiber, satellite cells typically reside in a quiescent state. Little information exists detailing satellite cell regulation of reversible G(0). One member of the mitosin family of centromere proteins, LEK1 (leucine/glutamic acid/lysine protein 1), is present in the nucleus of nondividing mouse satellite cells. The objective of this study was to evaluate LEK1 as a marker of quiescent bovine satellite cells (BSC) in vitro and in vivo. The BSC were isolated from young bull calves (< or =7 d) and cultured in vitro for up to 9 d before fixation and immunostaining for LEK1. Results demonstrated that all myogenic cells contain the protein, with immunostaining primarily within the nucleus and immediate perinuclear region. Immunocytochemical detection of LEK1 in cryosections of mature cows revealed that the protein was present in a fraction of satellite cells and muscle fiber nuclei. Approximately 20% of Pax7-expressing satellite cells contained LEK1. An equivalent percentage of myonuclei, as defined by nuclei within a dystrophin boundary, contained nuclear LEK1. To gain insight into the functional role of LEK1, BSC were transiently transfected with plasmids coding for putative dominant inhibitory LEK1 proteins [DeltaLEK1(991) and DeltaLEK1(911)] and evaluated for cell proliferation. Both forms of DeltaLEK1 inhibited (P < 0.05) BSC proliferation, as indicated by a decrease in Ki67 immunopositive cells. In C2C12 myoblasts, DeltaLEK1(911) inhibited (P < 0.05) myoblast determination protein 1 (MyoD)-directed muscle gene transcriptional activity; DeltaLEK1(991) had no effect on TnI-Luc transcription. By contrast, both DeltaLEK1 fusion proteins inhibited myogenin expression in BSC without disrupting myoblast fusion. These results provide evidence that LEK1 serves to coordinate proliferation and differentiation in myogenic cells. Coupling the immunostaining pattern and functional data, we propose that LEK1 may serve as a useful marker for satellite cells that are preparing to fuse into adjacent fibers as well as an indicator of recently added myonuclei.
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Bovinos/fisiología , Proteínas Cromosómicas no Histona/fisiología , Desarrollo de Músculos/fisiología , Fibras Musculares Esqueléticas/fisiología , Células Satélite del Músculo Esquelético/fisiología , Animales , Western Blotting/veterinaria , Proliferación Celular , Femenino , Inmunohistoquímica/veterinaria , Masculino , Fibras Musculares Esqueléticas/citología , Mutagénesis , Plásmidos/farmacología , Células Satélite del Músculo Esquelético/citología , Transfección/veterinariaRESUMEN
1. Growing knowledge of the pathogenesis of human immunodeficiency virus (HIV)-1 infection has led to the identification of potential virus sanctuary sites within the central nervous system and gut-associated lymphoid tissue. 2. Maraviroc is a novel CCR5 antagonist for the treatment of HIV-1 infection. Disposition studies have been performed within the preclinical testing of maraviroc to determine its distribution to these anatomical sites. 3. Maraviroc, which is a substrate of the efflux transporter P-glycoprotein, shows limited distribution to the central nervous system as evidenced by cerebrospinal fluid concentrations that were 10% of the free plasma concentration following intravenous infusion to rats. Tissue distribution studies also indicated limited distribution of radioactivity into brain tissue of rats. 4. Radioactivity in gut-associated lymphoid tissue lymph nodes exceeded the concentrations in blood and concentrations in the contents of thoracic ducts of the lymphatic system were similar to blood levels following intravenous administration to rats.
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Encéfalo/metabolismo , Ciclohexanos/farmacocinética , Inhibidores de Fusión de VIH/farmacocinética , Mucosa Intestinal/metabolismo , Tejido Linfoide/metabolismo , Triazoles/farmacocinética , Animales , Ciclohexanos/administración & dosificación , Evaluación Preclínica de Medicamentos , Estudios de Factibilidad , VIH/efectos de los fármacos , Inhibidores de Fusión de VIH/administración & dosificación , Masculino , Maraviroc , Ratas , Distribución Tisular , Triazoles/administración & dosificaciónRESUMEN
Two experiments evaluated the effects of conventional and natural feedlot management systems (MS) on ractopamine-HCl (RAC) response in yearling steers. Feedlot performance, carcass characteristics, skeletal muscle gene expression, and circulating IGF-I concentrations were measured. The conventional system included a combined trenbolone acetate and estradiol implant, Revalor-S (IMP), as well as monensin-tylosin feed additives (IA). Treatments were arranged in a 2 x 2 factorial and included: 1) natural (NAT): no IMP-no IA, no RAC; 2) natural plus (NAT+): no IMP-no IA, RAC; 3) conventional (CON): IMP-IA, no RAC; and 4) conventional plus (CON+): IMP-IA, RAC. In Exp. 1, one hundred twenty crossbred steers (initial BW = 400 +/- 26 kg) were allotted randomly to treatment in a randomized complete block design (BW was blocking criteria); pen was the experimental unit. In Exp. 2, twenty-four individually fed crossbred steers (initial BW = 452 +/- 25 kg) were used in a randomized complete block design (BW was blocking criteria) and assigned to the same treatments as Exp. 1, with 6 steers/treatment. In Exp. 2, serum was harvested on d 0 and 31 and within the 28-d RAC feeding period, at d 0, 14, and 28. Longissimus biopsy samples were taken on d 0, 14, and 28 of the RAC feeding period for mRNA analysis of beta-adrenergic receptors and steady-state IGF-I mRNA. In Exp. 1, ADG, G:F, final BW, and HCW were greatest for CON+ (P < 0.01). During the final 37 d, RAC increased ADG (P = 0.05) and increased overall G:F (P = 0.02). Marbling score was reduced (P = 0.02), and yield grade was improved with RAC (P = 0.02), but RAC did not affect dressing percentage (P = 0.96) or HCW (P = 0.31). In Exp. 2, MS x RAC interactions were detected in ADG and G:F the last 28 d, overall ADG and overall G:F, final BW, and HCW (P < 0.01). Dressing percentage, yield grade, and marbling score were not altered by MS or RAC (P > 0.10). Circulating IGF-I concentration was increased on d 31 by the conventional MS, and concentration was greater throughout the study than NAT steers (P < 0.01). Circulating IGF-I concentrations were not changed by RAC (P = 0.49). Abundance of beta(1)-AR mRNA tended to increase (P = 0.09) with RAC, but RAC did not affect beta(2)-AR, beta(3)-AR, or IGF-I mRNA (P > 0.40). Management system did not affect beta(1)-AR, beta(2)-AR, beta(3)-AR, or IGF-I mRNA (P > 0.18), yet a trend (P = 0.06) for MS x RAC for beta(2)-AR mRNA was detected. These results indicate that response to RAC is affected by feedlot management practices.
Asunto(s)
Agonistas Adrenérgicos beta/farmacología , Crianza de Animales Domésticos/métodos , Bovinos/fisiología , Fenetilaminas/farmacología , Fenómenos Fisiológicos Nutricionales de los Animales , Animales , Biopsia/veterinaria , Peso Corporal , Bovinos/genética , Bovinos/metabolismo , Factor I del Crecimiento Similar a la Insulina/biosíntesis , Factor I del Crecimiento Similar a la Insulina/genética , Masculino , Músculo Esquelético/efectos de los fármacos , Músculo Esquelético/metabolismo , ARN Mensajero/biosíntesis , ARN Mensajero/genética , Distribución Aleatoria , Receptores Adrenérgicos beta/biosíntesis , Receptores Adrenérgicos beta/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa/veterinariaRESUMEN
Six Holstein steers (231 +/- 17 kg) housed in metabolism crates were used in a randomized complete block design with three blocks of two steers based on previous serum insulin-like growth factor (IGF)-I concentrations. One of the two steers in each block was implanted with 120 mg trenbolone acetate and 24 mg oestradiol-17beta on day 0. None of the steers was fed ractopamine-HCl in the initial 28 days, and then all steers were fed 200 mg of ractopamine-HCl per steer daily from day 28 until the end of the trial. Steers were fed a corn-based diet (62% rolled corn, 20% expeller soya bean meal and 15% alfalfa hay) twice daily with an average dry matter intake of 4.8 kg/day. Blood and M. longissimus biopsy samples were collected prior to implantation and on days 14, 28, 42 and 56. There was an implant x ractopamine interaction for retained nitrogen (p < 0.05); ractopamine feeding led to only small improvements in nitrogen retention for implanted steers (45.9 g/day vs. 44.5 g/day), whereas ractopamine led to larger increases in nitrogen retention for non-implanted steers (39.0 g/day vs. 30.4 g/day). Implantation increased (p < 0.05) and ractopamine tended to decrease (p = 0.06) serum IGF-I concentrations. Implantation tended to increase (p = 0.16) and ractopamine decreased (p < 0.05) mRNA expression of IGF-I in the M. longissimus. Ractopamine decreased mRNA expression of beta(1)- and beta(2)-receptors in M. longissimus (p
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Bovinos/metabolismo , Estradiol/farmacología , Músculo Esquelético/metabolismo , Nitrógeno/metabolismo , Fenetilaminas/farmacología , Acetato de Trembolona/análogos & derivados , Aumento de Peso/efectos de los fármacos , Alimentación Animal , Fenómenos Fisiológicos Nutricionales de los Animales , Animales , Bovinos/sangre , Bovinos/crecimiento & desarrollo , Digestión , Combinación de Medicamentos , Implantes de Medicamentos , Interacciones Farmacológicas , Factor I del Crecimiento Similar a la Insulina/metabolismo , Masculino , Músculo Esquelético/patología , Nitrógeno/sangre , Reacción en Cadena de la Polimerasa/métodos , Reacción en Cadena de la Polimerasa/veterinaria , ARN Mensajero/metabolismo , Acetato de Trembolona/farmacologíaRESUMEN
An experiment was conducted to determine the relationship between feeding ractopamine and different amounts of MP on growth and carcass characteristics of feedlot heifers. Seventy-two crossbred heifers (475 kg of initial BW) were fed individually a diet based on steam-flaked corn for ad libitum intake for 29 d. Heifers were implanted with 140 mg of trenbolone acetate and 14 mg of estradiol-17beta 60 d before the experiment. Treatments were arranged as a 2 x 3 factorial and included 0 or 200 mg of ractopamine-HCl (23 ppm)/ d, and urea, solvent soybean meal, or expeller soybean meal (ESBM) as the predominant protein supplement. The amounts of MP supplied by the urea, solvent soybean meal, and ESBM diets were 688, 761, and 808 g/ d, respectively, calculated according to level 1 of the NRC model. Body weights were obtained 1 d before ractopamine feeding and at slaughter. Blood samples were obtained 1 d before starting the experiment and 13 d later. Ractopamine improved ADG, efficiency of gain, carcass-adjusted ADG, and carcass-adjusted efficiency of gain (P < 0.01). For ADG, heifers demonstrated a ractopamine x protein source interaction (P < 0.05); heifers not fed ractopamine had greater ADG when fed ESBM than when fed urea, whereas for heifers fed ractopamine there were no differences (P > or = 0.10) among protein supplements. This interaction was not observed for carcass-adjusted ADG (P = 0.60). Final live weights (P = 0.02) and carcass weights (P = 0.01) were greater with ractopamine feeding. Carcass marbling scores and yield grades were not affected by ractopamine or protein source (P > or = 0.39). Plasma total alpha-amino N and glucose concentrations decreased more from pretreatment concentrations when heifers were fed ractopamine (P < 0.05). Feeding ractopamine to heifers for 28 d before slaughter improved ADG and efficiency of gain without any large effects on carcass characteristics. The MP supply does not need to be increased from that provided by finishing diets based on steam-flaked corn with urea as the primary N supplement to allow the maximal response to ractopamine by finishing heifers.
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Agonistas Adrenérgicos beta/farmacología , Bovinos/crecimiento & desarrollo , Proteínas en la Dieta/administración & dosificación , Fenetilaminas/farmacología , Agonistas Adrenérgicos beta/administración & dosificación , Alimentación Animal/análisis , Animales , Glucemia/análisis , Bovinos/fisiología , Proteínas en la Dieta/clasificación , Proteínas en la Dieta/metabolismo , Suplementos Dietéticos , Femenino , Ácido Láctico/sangre , Fenetilaminas/administración & dosificación , Distribución Aleatoria , Urea/sangreRESUMEN
In Experiment 1, lambs were randomly assigned to 0.25, 1.00, 2.50, 5.00 and 10.00 g/day of dietary ruminally protected L-carnitine (RPLC) and were allowed to adapt for 20 days. Plasma samples were obtained at 0, 120 and 240 min after RPLC feeding. Plasma L-carnitine (LC) concentrations increased (p<0.01) for all levels of RPLC treatment, however, no differences were observed due to level of RPLC or time. Plasma LC concentrations were 27.05 and 57.83 micromol/l for baseline and pooled RPLC treated sheep, respectively. In Experiment 2, lambs were randomly assigned to 0, 0.125, 1.06 and 2.0 g/day of RPLC and were adapted as in Experiment 1. Plasma was collected at 0, 15, 30, 60, 90, 180, 240 and 360 min after oral ammonia challenge (300 mg/kg BW urea). Plasma LC concentrations increased with treatment relative to control (p<0.01). Plasma LC concentrations were 35.7, 44.2, 60.5 and 65.7 micromol/l for the 0, 0.125, 1.06 and 2.0 g/day treatments, respectively. RPLC tended to decrease plasma ammonia at some time points (time x treatment; p=0.10). We conclude that RPLC increased plasma LC concentrations, but had only modest effects on plasma ammonia concentrations and had no effect on plasma urea or glucose concentrations.
Asunto(s)
Amoníaco/sangre , Carnitina/farmacología , Carnitina/farmacocinética , Rumen/metabolismo , Ovinos/sangre , Adaptación Fisiológica , Amoníaco/toxicidad , Alimentación Animal , Fenómenos Fisiológicos Nutricionales de los Animales , Animales , Área Bajo la Curva , Glucemia/metabolismo , Carnitina/sangre , Relación Dosis-Respuesta a Droga , Distribución Aleatoria , Urea/sangreRESUMEN
The pharmaceutical industry continues to look for ways to reduce drug candidate attrition throughout the drug discovery and development process. A significant cause of attrition is due to safety issues arising either as a result of animal toxicity testing or in the clinical programme itself. A factor in the assessment of safety during early drug development is the pharmacokinetic profile of the compound. This allows safety data to be considered in the light of systemic drug exposure and therefore permits a quantitative assessment. This is particularly applicable when assessing the risk of a new chemical entity (NCE) in relation to safety parameters such as QT interval prolongation, where free plasma concentrations have been shown to be predictive of this property in relation to potency in preclinical testing. Prior to actual human exposure it is therefore important to be able to predict reliably the pharmacokinetic behaviour of an NCE in order to place such safety findings into a quantitative risk context. The emerging science of pharmacogenetics is likely to further our ability to assess the risk of NCEs to populations and individuals due to genetic variance. The drug metabolizing enzyme CYP2D6 has been recognized as providing the potential to result in widely differing systemic drug exposure in the patient population due to polymorphic expression. Further knowledge is likely to add to our understanding of population differences in exposure and response and aid in the identification of risk factors. One potential strategy for improving the effectiveness of the drug discovery process is to obtain clinical pharmacokinetic data more rapidly in order to assess more accurately the potential for both efficacy and safety of an NCE. Whilst procedures and technologies are available that allow this on the microdose scale, it is important that we recognize potential limitations of these approaches in order that they can be applied beneficially.
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Diseño de Fármacos , Farmacocinética , Farmacología Clínica , Toxicología/métodos , Humanos , FarmacogenéticaRESUMEN
Voriconazole is a new triazole antifungal agent with potent, wide-spectrum activity. Its pharmacokinetics and metabolism have been studied in mouse, rat, rabbit, dog, guinea pig, and humans after single and multiple administration by both oral and intravenous routes. Absorption of voriconazole is essentially complete in all species. The elimination of voriconazole is characterized by non-linear pharmacokinetics in all species. Consequently, pharmacokinetic parameters are dependent upon dose, and a superproportional increase in area under the curve is seen with increasing dose in rat and dog toxicology studies. Following multiple administration, there is a decrease in systemic exposure. This is most pronounced in mouse and rat, less so in dog, and not observed in guinea pig or rabbit. Repeat-dose toxicology studies in mouse, rat, and dog have demonstrated that induction of cytochrome P450 by voriconazole (autoinduction of metabolism) is responsible for the decreased exposure in these species. Autoinduction of metabolism is not observed in humans, and plasma steady-state concentrations remain constant with time. Voriconazole is extensively metabolized in all species. The major pathways in humans involve fluoropyrimidine N-oxidation, fluoropyrimidine hydroxylation, and methyl hydroxylation. Also, N-oxidation facilitates cleavage of the molecule, resulting in loss of the fluoropyrimidine moiety and subsequent conjugation with glucuronic acid. Major pathways are represented in animal species. The major circulating metabolite in rat, dog, and human is the N-oxide of voriconazole. It is not thought to contribute to efficacy since it is at least 100-fold less potent than voriconazole against fungal pathogens in vitro.
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Óxidos N-Cíclicos/metabolismo , Óxidos N-Cíclicos/farmacocinética , Pirimidinas/metabolismo , Pirimidinas/farmacocinética , Triazoles/metabolismo , Triazoles/farmacocinética , Adulto , Animales , Área Bajo la Curva , Cromatografía Líquida de Alta Presión , Óxidos N-Cíclicos/sangre , Óxidos N-Cíclicos/orina , Perros , Relación Dosis-Respuesta a Droga , Heces/química , Femenino , Ácido Glucurónico/metabolismo , Cobayas , Humanos , Masculino , Ratones , Óxidos/metabolismo , Unión Proteica , Pirimidinas/sangre , Pirimidinas/orina , Conejos , Ratas , Ratas Sprague-Dawley , Conteo por Cintilación , Caracteres Sexuales , Especificidad de la Especie , Triazoles/sangre , Triazoles/orina , Rayos Ultravioleta , VoriconazolRESUMEN
The pharmacokinetics of selamectin were evaluated in cats and dogs, following intravenous (0.05, 0.1 and 0.2 mg/kg), topical (24 mg/kg) and oral (24 mg/kg) administration. Following selamectin administration, serial blood samples were collected and plasma concentrations were determined by high performance liquid chromatography (HPLC). After intravenous administration of selamectin to cats and dogs, the mean maximum plasma concentrations and area under the concentration-time curve (AUC) were linearly related to the dose, and mean systemic clearance (Clb) and steady-state volume of distribution (Vd(ss)) were independent of dose. Plasma concentrations after intravenous administration declined polyexponentially in cats and biphasically in dogs, with mean terminal phase half-lives (t(1/2)) of approximately 69 h in cats and 14 h in dogs. In cats, overall Clb was 0.470 +/- 0.039 mL/min/kg (+/-SD) and overall Vd(ss) was 2.19 +/- 0.05 L/kg, compared with values of 1.18 +/- 0.31 mL/min/kg and 1.24 +/- 0.26 L/kg, respectively, in dogs. After topical administration, the mean C(max) in cats was 5513 +/- 2173 ng/mL reached at a time (T(max)) of 15 +/- 12 h postadministration; in dogs, C(max) was 86.5 +/- 34.0 ng/mL at T(max) of 72 +/- 48 h. Bioavailability was 74% in cats and 4.4% in dogs. Following oral administration to cats, mean C(max) was 11,929 +/- 5922 ng/mL at T(max) of 7 +/- 6 h and bioavailability was 109%. In dogs, mean C(max) was 7630 +/- 3140 ng/mL at T(max) of 8 +/- 5 h and bioavailability was 62%. There were no selamectin-related adverse effects and no sex differences in pharmacokinetic parameters. Linearity was established in cats and dogs for plasma concentrations up to 874 and 636 ng/mL, respectively. Pharmacokinetic evaluations for selamectin following intravenous administration indicated a slower elimination from the central compartment in cats than in dogs. This was reflected in slower clearance and longer t(1/2) in cats, probably as a result of species-related differences in metabolism and excretion. Inter-species differences in pharmacokinetic profiles were also observed following topical administration where differences in transdermal flux rates may have contributed to the overall differences in systemic bioavailability.
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Antiparasitarios/farmacocinética , Ivermectina/análogos & derivados , Ivermectina/farmacocinética , Administración Oral , Administración Tópica , Animales , Antiparasitarios/administración & dosificación , Antiparasitarios/sangre , Área Bajo la Curva , Gatos , Cromatografía Líquida de Alta Presión , Perros , Relación Dosis-Respuesta a Droga , Femenino , Semivida , Inyecciones Intravenosas , Ivermectina/administración & dosificación , Ivermectina/sangre , MasculinoRESUMEN
A series of potent indole-containing endothelin antagonists were evaluated in rat pharmacokinetic studies as part of a rational drug design program. Early compounds in this series were found to show poor gastrointestinal absorption, limiting their utility as oral agents. Structural modifications and pharmacokinetic studies indicated that reducing the overall H-bonding potential, through a reduction in the number of H-bond donors and acceptors, could increase absorption of the molecules. There was a correlation between calculated H-bonding capacity and rate of permeability across Caco-2 monolayers for this series of compounds. Caco-2 permeability was also shown to be indicative of the estimated extent of absorption in rats. Balancing the requirements of absorption and systemic clearance lead to the selection of an alcohol-containing compound, compound 7a (single enantiomer of compound 7) that was moderately absorbed after oral administration and converted to an active acid metabolite, which itself was of low intrinsic clearance. Species differences were observed between the absorption of compound 7a in rat and dog and also in the extent of conversion to the acid metabolite. Absorption was estimated at 30% in rat and 100% in dog. Approximately 30% of the absorbed drug was converted to systemically available acid metabolite in rat, compared with only 3% in dog.
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Antagonistas de los Receptores de Endotelina , Endotelina-1/metabolismo , Indoles/administración & dosificación , Indoles/farmacocinética , Absorción Intestinal/fisiología , Administración Oral , Animales , Células CACO-2/metabolismo , Perros , Femenino , Humanos , Indoles/química , Masculino , Ratas , Ratas Sprague-Dawley , Receptor de Endotelina A , Especificidad de la Especie , Relación Estructura-ActividadRESUMEN
1. UK-343,664 is a novel potent and selective PDE5 inhibitor. Plasma clearances in the male and female rat were high (120 and 54 ml min(-1) kg(-1)), giving rise to short elimination half-lives (0.2 and 0.3h respectively). Lower clearance in dog (14 ml min(-1) kg(-1)) was the primary factor resulting in a longer elimination half-life (3.7 h). The higher clearance in rat than dog was in agreement with in vitro metabolism rates in hepatic microsomes. 2. The volume of distribution was lower in rat (1.3-2.11 kg(-1)) compared with dog (4.61 kg(-1)) probably due to increased plasma protein binding in rat (96 versus 81% in dog). 3. Oral bioavailabilities were 2, 12 and 70% in the male and female rat and dog respectively. Tmax < or = 0.5 h in all animals. 4. In multiple oral dose studies, increased systemic exposure was seen with increasing dose up to doses of 200 mg kg(-1) in rat and 150 mg kg(-1) in dog. A marked super-proportional increase in the male rat indicated a capacity-limited clearance at high doses. 5. At the maximal dose of 200 mg kg(-1) in the female rat, no clinical signs were observed after 14 days of treatment. Only minimal signs were recorded in the male rat and dog at the highest dose levels investigated. 6. After single oral or intravenous doses of [14C]-UK-343,664, the majority of radioactivity was excreted in the faeces of both species. 7. UK-343,664 was extensively metabolized in both rat and dog. The major primary pathways in dog involved piperazine N-deethylation and loss of a two carbon fragment from the piperazine ring (N,N'-de-ethylation). More extensive metabolism in the rat included additional notable metalbolites arising from hydroxylation and lactamization of the piperazine ring, which were only minor metabolites in the dog.
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3',5'-GMP Cíclico Fosfodiesterasas/antagonistas & inhibidores , Inhibidores de Fosfodiesterasa/metabolismo , Inhibidores de Fosfodiesterasa/farmacocinética , Piperazinas/metabolismo , Piperazinas/farmacocinética , Pirimidinonas/metabolismo , Pirimidinonas/farmacocinética , Administración Oral , Animales , Proteínas Sanguíneas/metabolismo , Radioisótopos de Carbono , Fosfodiesterasas de Nucleótidos Cíclicos Tipo 5 , Perros , Heces/química , Femenino , Inyecciones Intravenosas , Masculino , Inhibidores de Fosfodiesterasa/administración & dosificación , Piperazinas/administración & dosificación , Unión Proteica , Pirimidinonas/administración & dosificación , Ratas , Ratas Sprague-Dawley , Caracteres Sexuales , Especificidad de la EspecieRESUMEN
1. UK-343,664 is a potent and specific PDE5 inhibitor. Following single oral doses to human volunteers, it exhibited non-proportional pharmacokinetics over the dose range 30-800 mg. Over this 27-fold dose range, Cmax and AUCt increased 247- and 287-fold respectively. The half-life (4-6 h) was similar at all doses. No systemic exposure was quantifiable at doses <10 mg. 2. UK-343,664 is a lipophilic molecule (log D7.4 = 3.1) and as such is expected to be cleared mainly by metabolism. Based on studies with expressed human P450 enzymes it was concluded that the metabolism of UK-343,664 was predominantly mediated by CYP3A4. With a moderate Km = 76 microM for this enzyme, saturation of first-pass metabolism alone was considered unlikely to account for the non-proportional pharmacokinetics. 3. UK-343,664 showed high affinity for P-glycoprotein in vitro, with a Km = 7.3 microM. In transport studies in LLC-PK1 cell monolayers transfected with P-glycoprotein, UK343,664 showed marked polarized transport which was concentration dependent. 4. The high affinity of UK-343,664 for P-glycoprotein is considered to be the primary source of the non-proportional pharmacokinetic profile observed in man.