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The rodent granular retrosplenial cortex (gRSC) has reciprocal connections to the hippocampus to support fear memories. Although activity-dependent plasticity occurs within the RSC during memory formation, the intrinsic and morphological properties of RSC neurons are poorly understood. The present study used whole-cell recordings to examine intrinsic neuronal firing and morphology of neurons in layer 2/3 (L2/3) and layer 5 (L5) of the gRSC in adult male rats. Five different classifications were observed: regular-spiking (RS), regular-spiking afterdepolarization (RSADP), late-spiking (LS), burst-spiking (BS), and fast-spiking (FS) neurons. RSADP neurons were the most commonly observed neuronal class, identified by their robust spike frequency adaptation and pronounced afterdepolarization (ADP) following an action potential (AP). They also had the most extensive dendritic branching compared with other cell types. LS neurons were predominantly found in L2/3 and exhibited a long delay before onset of their initial AP. They also had reduced dendritic branching compared with other cell types. BS neurons were limited to L5 and generated an initial burst of two or more APs. FS neurons demonstrated sustained firing and little frequency adaptation and were the only nonpyramidal firing type. Relative to adults, RS neurons from juvenile rats (PND 14-30) lacked an ADP and were less excitable. Bath application of group 1 mGluR blockers attenuated the ADP in adult neurons. In other fear-related brain structures, the ADP has been shown to enhance excitability and synaptic plasticity. Thus, understanding cellular mechanisms of the gRSC will provide insight regarding its precise role in memory-related processes across the lifespan.NEW & NOTEWORTHY This is the first study to demonstrate that granular retrosplenial cortical (gRSC) neurons exhibit five distinctive firing types: regular spiking (RS), regular spiking with an afterdepolarization (RSADP), late spiking (LS), burst spiking (BS), and fast spiking (FS). RSADP neurons were the most frequently observed cell type in adult gRSC neurons. Interestingly, RS neurons without an ADP were most common in gRSC neurons of juvenile rats (PND 14-30). Thus, the ADP property, which was previously shown to enhance neuronal excitability, emerges during development.
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Fenômenos Eletrofisiológicos/fisiologia , Giro do Cíngulo/citologia , Giro do Cíngulo/fisiologia , Neurônios/fisiologia , Fatores Etários , Animais , Masculino , Técnicas de Patch-Clamp , Ratos , Ratos Endogâmicos F344RESUMO
Experience-dependent neuronal plasticity is a fundamental substrate of learning and memory. Intrinsic excitability is a form of neuronal plasticity that can be altered by learning and indicates the pattern of neuronal responding to external stimuli (e.g. a learning or synaptic event). Associative fear conditioning is one form of learning that alters intrinsic excitability, reflecting an experience-dependent change in neuronal function. After fear conditioning, intrinsic excitability changes are evident in brain regions that are a critical part of the fear circuit, including the amygdala, hippocampus, retrosplenial cortex, and prefrontal cortex. Some of these changes are transient and/or reversed by extinction as well as learning-specific (i.e. they are not observed in neurons from control animals). This review will explore how intrinsic neuronal excitability changes within brain structures that are critical for fear learning, and it will also discuss evidence promoting intrinsic excitability as a vital mechanism of associative fear memories. This work has raised interesting questions regarding the role of fear learning in changes of intrinsic excitability within specific subpopulations of neurons, including those that express immediate early genes and thus demonstrate experience-dependent activity, as well as in neurons classified as having a specific firing type (e.g. burst-spiking vs. regular-spiking). These findings have interesting implications for how intrinsic excitability can serve as a neural substrate of learning and memory, and suggest that intrinsic plasticity within specific subpopulations of neurons may promote consolidation of the memory trace in a flexible and efficient manner.
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Potenciais de Ação , Encéfalo/fisiologia , Condicionamento Clássico/fisiologia , Medo/fisiologia , Memória/fisiologia , Plasticidade Neuronal/fisiologia , Neurônios/fisiologia , Tonsila do Cerebelo/fisiologia , Animais , Extinção Psicológica/fisiologia , Giro do Cíngulo/fisiologia , Hipocampo/fisiologia , Córtex Pré-Frontal/fisiologiaRESUMO
OBJECTIVE: To describe perioperative characteristics and outcomes of dogs surgically treated for intestinal intussusception. STUDY DESIGN: Multi-institutional, retrospective study. ANIMALS: One hundred fifty-three client-owned dogs with intestinal intussusception. METHODS: Dogs were included when they had undergone surgical treatment of a confirmed intestinal intussusception. Medical records were reviewed for demographics and clinical data, including surgical complications (graded 1-4). Follow-up was obtained via telephone interview with owners and referring veterinarians. RESULTS: Dogs had a median age of 10 months (range, 2-156), and the most common location for intussusception was ileocolic (66/153 [43%]). Most cases had no identifiable cause (104/155 [67%]). Intestinal resection and anastomosis (IRA) was performed in 129 of 153 (84%) dogs; enteroplication was performed in 28 of 153 (18%) dogs, including 13 with and 15 without IRA. Intraoperative complications occurred in 10 of 153 (7%) dogs, all involving intestinal damage during attempted manual reduction. The median duration of follow-up after discharge was 334 days (interquartile range, 15-990; range, 1-3302). Postoperative complications occurred in 53 of 153 (35%) dogs, including 22 of 153 (14%) with severe (grade 3 or 4) events. Diarrhea, regurgitation, and septic peritonitis were the most common postoperative complications; intussusception recurred in four of 153 (3%) dogs, all within 72 hours postoperatively. Fourteen-day postoperative mortality rate was 6%. CONCLUSION: Surgical treatment of intestinal intussusception was curative in most dogs, even when an underlying cause was not identified. Surgical complications were common, including a 14% risk of life-threatening short-term complications. CLINICAL SIGNIFICANCE: Surgical treatment of intestinal intussusception offers an excellent prognosis, but the potential life-threatening complications should be considered.
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Procedimentos Cirúrgicos do Sistema Digestório/veterinária , Doenças do Cão/cirurgia , Complicações Intraoperatórias/veterinária , Intussuscepção/veterinária , Complicações Pós-Operatórias/veterinária , Anastomose Cirúrgica/veterinária , Animais , Cães , Feminino , Intussuscepção/cirurgia , Masculino , Recidiva , Estudos RetrospectivosRESUMO
Medial prefrontal cortex (mPFC) is critical for the expression of long-term conditioned fear. However, the neural circuits involving fear memory acquisition and retrieval are still unclear. Two subregions within mPFC that have received a lot of attention are the prelimbic (PL) and infralimbic (IL) cortices (e.g., Santini E, Quirk GJ, Porter JT. J Neurosci 28: 4028-4036, 2008; Song C, Ehlers VL, Moyer JR Jr J Neurosci 35: 13511-13524, 2015). Interestingly, PL and IL may play distinct roles during fear memory acquisition and retrieval but the underlying mechanism is poorly understood. One possibility is that the intrinsic membrane properties differ between these subregions. Thus, the current study was carried out to characterize the basic membrane properties of mPFC neurons in different layers and subregions. We found that pyramidal neurons in L2/3 were more hyperpolarized and less excitable than in L5. This was observed in both IL and PL and was associated with an enhanced h-current in L5 neurons. Within L2/3, IL neurons were more excitable than those in PL, which may be due to a lower spike threshold and higher input resistance in IL neurons. Within L5, the intrinsic excitability was comparable between neurons obtained in IL and PL. Thus, the heterogeneity in physiological properties of mPFC neurons may underlie the observed subregion-specific contribution of mPFC in cognitive function and emotional control, such as fear memory expression. NEW & NOTEWORTHY This is the first study to demonstrate that medial prefrontal cortical (mPFC) neurons are heterogeneous in both a layer- and a subregion-specific manner. Specifically, L5 neurons are more depolarized and more excitable than those neurons in L2/3, which is likely due to variations in h-current. Also, infralimbic neurons are more excitable than those of prelimbic neurons in layer 2/3, which may be due to differences in certain intrinsic properties, including input resistance and spike threshold.
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Córtex Pré-Frontal/citologia , Células Piramidais/fisiologia , Potenciais de Ação , Animais , Medo , Masculino , Memória , Córtex Pré-Frontal/fisiologia , Células Piramidais/classificação , Ratos , Ratos Sprague-DawleyRESUMO
Neuronal activity in medial prefrontal cortex (mPFC) is critical for the formation of trace fear memory, yet the cellular mechanisms underlying these memories remain unclear. One possibility involves the modulation of intrinsic excitability within mPFC neurons that project to the basolateral complex of amygdala (BLA). The current study used a combination of retrograde labeling and in vitro whole-cell patch-clamp recordings to examine the effect of trace fear conditioning on the intrinsic excitability of layer 5 mPFC-BLA projection neurons in adult rats. Trace fear conditioning significantly enhanced the intrinsic excitability of regular spiking infralimbic (IL) projection neurons, as evidenced by an increase in the number of action potentials after current injection. These changes were also associated with a reduction in spike threshold and an increase in h current. In contrast, trace fear conditioning reduced the excitability of regular spiking prelimbic (PL) projection neurons, through a learning-related decrease of input resistance. Interestingly, the amount of conditioned freezing was (1) positively correlated with excitability of IL-BLA projection neurons after conditioning and (2) negatively correlated with excitability of PL-BLA projection neurons after extinction. Trace fear conditioning also significantly enhanced the excitability of burst spiking PL-BLA projection neurons. In both regions, conditioning-induced plasticity was learning specific (observed in conditioned but not in pseudoconditioned rats), flexible (reversed by extinction), and transient (lasted <10 d). Together, these data suggest that intrinsic plasticity within mPFC-BLA projection neurons occurs in a subregion- and cell-type-specific manner during acquisition, consolidation, and extinction of trace fear conditioning. Significance statement: Frontal lobe-related function is vital for a variety of important behaviors, some of which decline during aging. This study involves a novel combination of electrophysiological recordings from fluorescently labeled mPFC-to-amygdala projection neurons in rats with acquisition and extinction of trace fear conditioning to determine how specific neurons change during behavior. This is the first study to demonstrate that trace fear conditioning significantly alters the intrinsic excitability of mPFC-to-amygdala projection neurons in a subregion- and cell-type-specific manner, which is also transient and reversed by extinction. These data are of broad interest to the neuroscientific community, and the results will inspire additional studies investigating the cellular mechanisms underlying circuit-specific changes within the brain as a result of associative learning and memory.
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Tonsila do Cerebelo/fisiologia , Condicionamento Clássico/fisiologia , Medo/fisiologia , Sistema Límbico/fisiologia , Vias Neurais/fisiologia , Córtex Pré-Frontal/fisiologia , Tonsila do Cerebelo/citologia , Animais , Fenômenos Eletrofisiológicos/fisiologia , Extinção Psicológica , Aprendizagem/fisiologia , Sistema Límbico/citologia , Masculino , Memória/fisiologia , Vias Neurais/citologia , Plasticidade Neuronal/fisiologia , Técnicas de Patch-Clamp , Córtex Pré-Frontal/citologia , Desempenho Psicomotor/fisiologia , Ratos , Ratos Endogâmicos F344RESUMO
Learning-induced modulation of neuronal intrinsic excitability is a metaplasticity mechanism that can impact the acquisition of new memories. Although the amygdala is important for emotional learning and other behaviors, including fear and anxiety, whether learning alters intrinsic excitability within the amygdala has received very little attention. Fear conditioning was combined with intracellular recordings to investigate the effects of learning on the intrinsic excitability of lateral amygdala (LA) neurons. To assess time-dependent changes, brain slices were prepared either immediately or 24-h post-conditioning. Fear conditioning significantly enhanced excitability of LA neurons, as evidenced by both decreased afterhyperpolarization (AHP) and increased neuronal firing. These changes were time-dependent such that reduced AHPs were evident at both time points whereas increased neuronal firing was only observed at the later (24-h) time point. Moreover, these changes occurred within a subset (32%) of LA neurons. Previous work also demonstrated that learning-related changes in synaptic plasticity are also evident in less than one-third of amygdala neurons, suggesting that the neurons undergoing intrinsic plasticity may be critical for fear memory. These data may be clinically relevant as enhanced LA excitability following fear learning could influence future amygdala-dependent behaviors.
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Tonsila do Cerebelo/fisiologia , Condicionamento Psicológico/fisiologia , Medo/fisiologia , Neurônios/fisiologia , Potenciais de Ação , Animais , Masculino , Ratos , Ratos Sprague-DawleyRESUMO
A series of isoprenylated coumarins has been designed, synthesized, and evaluated against human pancreatic adenocarcinoma cell line PANC-1 under nutrient-rich and nutrient-deprived conditions. The compounds described investigate the effect of isoprenyl chain length and positioning on cell growth inhibition. The majority of these compounds displayed cytotoxicity against PANC-1 cells selectively in the absence of essential amino acids, glucose, and serum, and showed no cytotoxicity under nutrient-rich conditions. In this study, compound 6 exhibited the highest cytotoxic activity with an LC50 value of 4µM and induced apoptosis-like morphological changes in PANC-1 cells after a 24-h incubation. The evaluated structure-activity relationships show that substitution at the 6-position and the presence of a farnesyl isoprenyl tail are important structural features for enhanced preferential cytotoxicity. These findings provide important information to designing other structural analogues for potential application as novel pancreatic antitumor agents.
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Antineoplásicos/farmacologia , Cumarínicos/farmacologia , Neoplasias Pancreáticas/patologia , Antineoplásicos/síntese química , Antineoplásicos/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Cumarínicos/síntese química , Cumarínicos/química , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Estrutura Molecular , Relação Estrutura-AtividadeRESUMO
"Use it or lose it" is a popular adage often associated with use-dependent enhancement of cognitive abilities. Much research has focused on understanding exactly how the brain changes as a function of experience. Such experience-dependent plasticity involves both structural and functional alterations that contribute to adaptive behaviors, such as learning and memory, as well as maladaptive behaviors, including anxiety disorders, phobias, and posttraumatic stress disorder. With the advancing age of our population, understanding how use-dependent plasticity changes across the lifespan may also help to promote healthy brain aging. A common misconception is that such experience-dependent plasticity (e.g., associative learning) is synonymous with synaptic plasticity. Other forms of plasticity also play a critical role in shaping adaptive changes within the nervous system, including intrinsic plasticity - a change in the intrinsic excitability of a neuron. Intrinsic plasticity can result from a change in the number, distribution or activity of various ion channels located throughout the neuron. Here, we review evidence that intrinsic plasticity is an important and evolutionarily conserved neural correlate of learning. Intrinsic plasticity acts as a metaplasticity mechanism by lowering the threshold for synaptic changes. Thus, learning-related intrinsic changes can facilitate future synaptic plasticity and learning. Such intrinsic changes can impact the allocation of a memory trace within a brain structure, and when compromised, can contribute to cognitive decline during the aging process. This unique role of intrinsic excitability can provide insight into how memories are formed and, more interestingly, how neurons that participate in a memory trace are selected. Most importantly, modulation of intrinsic excitability can allow for regulation of learning ability - this can prevent or provide treatment for cognitive decline not only in patients with clinical disorders but also in the aging population.
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Envelhecimento , Aprendizagem/fisiologia , Memória/fisiologia , Plasticidade Neuronal , Neurônios/fisiologia , Envelhecimento/fisiologia , Animais , Aplysia , Humanos , Camundongos , RatosRESUMO
Introduction: New learning results in modulation of intrinsic plasticity in the underlying brain regions. Such changes in intrinsic plasticity can influence allocation and encoding of future memories such that new memories encoded during the period of enhanced excitability are linked to the original memory. The temporal window during which the two memories interact depends upon the time course of intrinsic plasticity following new learning. Methods: Using the well-characterized lateral amygdala-dependent auditory fear conditioning as a behavioral paradigm, we investigated the time course of changes in intrinsic excitability within lateral amygdala neurons. Results: We found transient changes in the intrinsic excitability of amygdala neurons. Neuronal excitability was increased immediately following fear conditioning and persisted for up to 4 days post-learning but was back to naïve levels 10 days following fear conditioning. We also determined the relationship between learning-induced intrinsic and synaptic plasticity. Synaptic plasticity following fear conditioning was evident for up to 24 h but not 4 days later. Importantly, we demonstrated that the enhanced neuronal intrinsic excitability was evident in many of the same neurons that had undergone synaptic plasticity immediately following fear conditioning. Interestingly, such a correlation between synaptic and intrinsic plasticity following fear conditioning was no longer present 24 h post-learning. Discussion: These data demonstrate that intrinsic and synaptic changes following fear conditioning are transient and co-localized to the same neurons. Since intrinsic plasticity following fear conditioning is an important determinant for the allocation and consolidation of future amygdala-dependent memories, these findings establish a time course during which fear memories may influence each other.
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Experience-dependent synaptic and intrinsic plasticity are thought to be important substrates for learning-related changes in behavior. The present study combined trace fear conditioning with both extracellular and intracellular hippocampal recordings to study learning-related synaptic and intrinsic plasticity. Rats received one session of trace fear conditioning, followed by a brief conditioned stimulus (CS) test the next day. To relate behavioral performance with measures of hippocampal CA1 physiology, brain slices were prepared within 1 h of the CS test. In trace-conditioned rats, both synaptic plasticity and intrinsic excitability were significantly correlated with behavior such that better learning corresponded with enhanced long-term potentiation (LTP; r = 0.64, P < 0.05) and a smaller postburst afterhyperpolarization (AHP; r = -0.62, P < 0.05). Such correlations were not observed in pseudoconditioned rats, whose physiological data were comparable to those of poor learners and naive and chamber-exposed control rats. In addition, acquisition of trace fear conditioning did not enhance basal synaptic responses. Thus these data suggest that within the hippocampus both synaptic and intrinsic mechanisms are involved in the acquisition of trace fear conditioning.
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Condicionamento Psicológico/fisiologia , Medo/fisiologia , Hipocampo/fisiologia , Plasticidade Neuronal/fisiologia , Sinapses/fisiologia , Animais , Potenciação de Longa Duração/fisiologia , Masculino , Memória/fisiologia , Ratos , Ratos Endogâmicos F344RESUMO
A description and the performance of the very small angle neutron scattering diffractometer at the National Institute of Standards and Technology are presented. The measurement range of the instrument extends over three decades of momentum transfer q from 2â ×â 10-4 to 0.7â Å-1. The entire scattering angle range from 8â ×â 10-5 to π/6â rad (30°) can be measured simultaneously using three separate detector carriages on rails holding nine 2D detector arrays. Versatile choices of collimation options and neutron wavelength selection allow the q resolution and beam intensity to be optimized for the needs of the experiment. High q resolution is achieved using multiple converging-beam collimation with circular pinholes combined with refractive lenses and prisms. Relaxed vertical resolution with much higher beam intensity can be achieved with narrow slit collimation and a broad wavelength range chosen by truncating the moderator source distribution below 4â Å with a Be crystalline filter and above 8â Å with a supermirror deflector. Polarized beam measurements with full polarization analysis are also provided by a high-performance supermirror polarizer and spin flipper, capable of producing flipping ratios of over 100, along with a high-efficiency 3He polarization analyzer.
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Background: Hepatocellular carcinoma (HCC) is the most common form of primary liver cancer in dogs. Despite this, relatively few reports of this disease exist pertaining to prognostic factors and outcome. Aim: To evaluate factors associated with survival in dogs with all subtypes of HCC diagnosed on histopathology. Methods: A retrospective single institutional study was carried out on 94 client-owned dogs with a histopathologic diagnosis of HCC between 2007 and 2018 obtained by biopsy (21/94) or attempted definitive resection (73/94). Signalment, preoperative features, surgical findings, and postoperative outcomes were recorded. Associations between survival to discharge data were collected and univariable logistical regression was carried out. Kaplan-Meier survival analysis was carried out to identify negative risk factors for long-term prognosis. Results: The median survival time (MST) for all patients was 707 days (95% CI = 551-842). MST was not significantly different (p > 0.05) between patients who had suspected versus incidentally diagnosed HCC (695 vs. 775 days), between complete versus incomplete surgical margins (668 vs. 834 days), or between patients with massive subtype versus nodular/diffuse subtype (707 vs. 747 days). Logistical regression identified an association with the excision of the right medial lobe and risk of perioperative death (OR = 9.2, CI 1.5-55.9, p = 0.016). An American Society of Anesthesiologists score ≥4, disease present within the quadrate lobe, and elevated blood urea nitrogen, potassium or gamma-glutamyltransferase were identified as negative prognosticators during multivariable Cox regression. Preoperative imaging (ultrasound or CT) agreed with the surgical location in 91% of the cases. Preoperative cytology was consistent with a diagnosis of HCC in 15/32 (46.9%) cases. Conclusion: Type of diagnosis (incidental vs presumed), completeness of excision, and subtype were not associated with MST in this study. Preoperative identification of tumors within the central division may be related to a less favorable outcome. Results of preoperative cytology were not highly sensitive for identifying a malignancy.
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Carcinoma Hepatocelular/veterinária , Doenças do Cão/etiologia , Neoplasias Hepáticas/veterinária , Animais , Carcinoma Hepatocelular/classificação , Carcinoma Hepatocelular/diagnóstico , Carcinoma Hepatocelular/etiologia , Doenças do Cão/classificação , Doenças do Cão/diagnóstico , Cães , Estimativa de Kaplan-Meier , Neoplasias Hepáticas/classificação , Neoplasias Hepáticas/diagnóstico , Neoplasias Hepáticas/etiologia , Margens de Excisão , Prognóstico , Estudos Retrospectivos , Análise de SobrevidaRESUMO
INTRODUCTION: Cognitive deficits during aging are pervasive across species and learning paradigms. One of the major mechanisms thought to play a role in age-related memory decline is dysregulated calcium (Ca2+ ) homeostasis. Aging is associated with impaired function of several calcium-regulatory mechanisms, including calcium-binding proteins that normally support intracellular Ca2+ regulation. This age-related calcium-binding protein dysfunction and changes in expression lead to disrupted maintenance of intracellular Ca2+ , thus contributing to memory decline. Other work has found that age-related cognitive deficits can be mitigated by either blocking Ca2+ entry into the cytosol or preventing its release from intracellular Ca2+ stores. However, the effect of calcium-binding protein administration on cognitive function during aging is not well-understood. Our laboratory has previously shown that the calcium-binding protein apoaequorin (AQ) is neuroprotective during oxygen-glucose deprivation, a model of in vitro ischemia characterized by calcium-induced excitotoxicity. The current experiments assessed the effect of direct dorsal hippocampal AQ infusion on trace and context fear memory in adult and aged rats. METHODS: Adult (3-6 months) and aged (22-26 months) male F344 rats were randomly assigned to different experimental infusion groups before undergoing trace fear conditioning and testing. In experiment 1, rats received bilateral dorsal hippocampal infusions of either vehicle or AQ (4% w/v) 24 hr before trace fear conditioning. In experiment 2, rats received bilateral dorsal hippocampal infusions of either vehicle or 4% AQ 1 hr before trace fear conditioning and 1 hr before testing. RESULTS: Aged rats displayed impaired trace and context fear memory. While a single AQ infusion 24 hr before trace fear conditioning was insufficient to rescue age-related trace fear memory deficits, AQ infusion 1 hr before both conditioning and testing abolished age-related context fear memory deficits. CONCLUSIONS: These results suggest that intrahippocampal infusion of AQ may reverse aging-related deficits in hippocampus-dependent context fear memory.
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Condicionamento Clássico , Medo , Equorina , Animais , Apoproteínas , Hipocampo , Masculino , Memória , Ratos , Ratos Endogâmicos F344 , Proteínas RecombinantesRESUMO
Brain aging is accompanied by an accumulation of damaged proteins, which results from deterioration of cellular quality control mechanisms and decreased protein degradation. The ubiquitin-proteasome system (UPS) is the primary proteolytic mechanism responsible for targeted degradation. Recent work has established a critical role of the UPS in memory and synaptic plasticity, but the role of the UPS in age-related cognitive decline remains poorly understood. Here, we measured markers of UPS function and related them to fear memory in rats. Our results show that age-related memory deficits are associated with reductions in phosphorylation of the Rpt6 proteasome regulatory subunit and corresponding increases in lysine-48 (K48)-linked ubiquitin tagging within the basolateral amygdala. Increases in K48 polyubiquitination were also observed in the medial prefrontal cortex and dorsal hippocampus. These data suggest that protein degradation is a critical component of age-related memory deficits. This extends our understanding of the relationship between the UPS, aging, and memory, which is an important step toward the prevention and treatment of deficits associated with normal cognitive aging and memory-related neurodegenerative diseases.
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Tonsila do Cerebelo/metabolismo , Envelhecimento Cognitivo/psicologia , Condicionamento Clássico , Medo/fisiologia , Hipocampo/metabolismo , Transtornos da Memória/etiologia , Memória/fisiologia , Córtex Pré-Frontal/metabolismo , Complexo de Endopeptidases do Proteassoma/fisiologia , Proteólise , Ubiquitina/fisiologia , Animais , Masculino , Fosforilação , Complexo de Endopeptidases do Proteassoma/metabolismo , Ratos Endogâmicos F344 , Ubiquitina/metabolismoRESUMO
Amplification and overexpression of erbB2 (Her-2/neu) proto-oncogene has been linked to human malignancies including tumors of the breast, ovary, and stomach. It has been implicated in tumor growth, sensitivity to standard chemotherapy, prognosis of patients, and disease-free survival. Although the clinical use of trastuzumab (Herceptin) has prolonged the survival of breast cancer patients with erbB2-overexpressing tumors, there is an urgent need for more potent and orally bioavailable small-molecule inhibitors. CP-724,714 is a potent inhibitor of erbB2 receptor autophosphorylation in intact cells and is currently undergoing phase I clinical trials. Here, we describe the effects of CP-724,714 in vitro and in vivo in human breast cancer models. CP-724,714 is selective for inhibiting growth of HER2-driven cell lines. In addition, we show that it induces G1 cell cycle block in erbB2-overexpressing BT-474 human breast carcinoma cells and inhibits erbB2 autophosphorylation in xenografts when administered p.o. to athymic mice. It induces a marked reduction of extracellular signal-regulated kinase and Akt phosphorylation, tumor cell apoptosis, and release of caspase-3. P.o. administration (q.d. or b.i.d.) of CP-724,714 inhibits the growth of erbB2-overexpressing tumors in athymic mice without overt adverse effects.
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Inibidores de Proteínas Quinases/farmacologia , Quinazolinas/farmacologia , Receptor ErbB-2/antagonistas & inibidores , Animais , Apoptose/efeitos dos fármacos , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Ciclo Celular/efeitos dos fármacos , Processos de Crescimento Celular/efeitos dos fármacos , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Feminino , Humanos , Camundongos , Camundongos Nus , Células NIH 3T3 , Fosforilação/efeitos dos fármacos , Proto-Oncogene Mas , Proteínas Proto-Oncogênicas c-akt/metabolismo , Receptor ErbB-2/metabolismo , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Many factors govern conditioning effectiveness, including the intertrial interval (ITI) used during training. The present study systematically varied the training ITI during both trace and long-delay fear conditioning. Rats were trained using one of six different ITIs and subsequently tested for conditioning to the white noise conditioned stimulus (CS) and the training context. After trace conditioning, percent freezing to the CS was positively correlated with training ITI, whereas percent freezing to the context was negatively correlated with training ITI. In contrast, when rats were trained using a long-delay paradigm, freezing during the CS test session did not vary as a function of training ITI; rats exhibited robust freezing at all ITIs. The long-delay conditioned rats exhibited relatively low levels of freezing during the context test. Thus, trace is more sensitive than long-delay fear conditioning to variations in the training ITI. These data suggest that training ITI is an important variable to consider when evaluating age or treatment effects, where the optimal ITI may vary with advancing age or pharmacological treatment.
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Condicionamento Clássico/fisiologia , Medo , Memória/fisiologia , Estimulação Acústica , Análise de Variância , Animais , Comportamento Animal , Eletrochoque/efeitos adversos , Reação de Congelamento Cataléptica/fisiologia , Masculino , Ratos , Ratos Sprague-Dawley , Fatores de TempoRESUMO
PURPOSE: The insulin-like growth factor (IGF) signaling pathway is implicated in cellular mitogenesis, angiogenesis, tumor cell survival, and tumorigenesis. Inhibition of this pathway results in decreased cell growth, inhibition of tumor formation in animal models, and increased apoptosis in cells treated with cytotoxic chemotherapy. We generated and characterized a human monoclonal antibody that targeted the IGF receptor. EXPERIMENTAL DESIGN: By use of XenoMouse technology, we generated CP-751,871, a fully human IgG2 antibody with high affinity (K(d) = 1.5 nmol/L) for human IGF-1R and evaluated its biological, pharmacologic, and antitumor properties. RESULTS: This antibody blocks binding of IGF-1 to its receptor (IC(50) 1.8 nmol/L), IGF-1-induced receptor autophosphorylation (IC(50) 0.42 nmol/L) and induced the down-regulation of IGF-1R in vitro and in tumor xenografts. The extent of IGF-1R down-regulation in vivo was proportional to CP-751,871 concentrations in the serum of tumor-bearing mice. Pharmacokinetic profiles in cynomolgus monkeys indicated a close to linear increase of exposure following i.v. dosing of antibody in the range of 3 to 100 mg/kg. CP-751,871 showed significant antitumor activity both as a single agent and in combination with Adriamycin, 5-fluorouracil, or tamoxifen in multiple tumor models. A biomarker assay was developed to establish the relationship between circulating antibody concentrations and down-regulation of IGF-1R in peripheral blood cells. The concentration of CP-751,871 required to down-regulate 50% of IGF-1R on peripheral blood cells was 0.3 nmol/L. CONCLUSION: These data suggest that inhibition of the IGF cascade by use of this monoclonal antibody may be of clinical benefit in the treatment of human cancers.
Assuntos
Anticorpos Monoclonais/imunologia , Neoplasias Colorretais/patologia , Mieloma Múltiplo/patologia , Receptor IGF Tipo 1/imunologia , Receptor IGF Tipo 1/fisiologia , Animais , Antineoplásicos/farmacologia , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Modelos Animais de Doenças , Regulação para Baixo , Imunoglobulina G/imunologia , Fator de Crescimento Insulin-Like I/metabolismo , Macaca fascicularis , Camundongos , Fosforilação , Receptor IGF Tipo 1/biossíntese , Transdução de Sinais , Transplante Heterólogo , Células Tumorais CultivadasRESUMO
Aberrant expression or activity of epidermal growth factor receptor (EGFr) or the closely related p185(erbB2) can promote cell proliferation and survival and thereby contribute to tumorigenesis. Specific antibodies and low molecular-weight tyrosine kinase inhibitors of both proteins are in clinical trials for cancer treatment. CP-654577 is a potent inhibitor selective for p185(erbB2), relative to EGFr tyrosine kinase, and selectively reduces erbB2 autophosphorylation in intact cells. Treatment of SKBr3 human breast cancer cells with CP-654577 reduces the levels of the activated form of mitogen-activated protein kinase, increases the levels of cyclin-dependent kinase inhibitor p27(kip1) and reduces expression of cyclins D and E. These biochemical changes result in a reduced level of phosphorylated retinoblastoma protein and an inhibition of cell-cycle progression at G(1). Apoptosis is triggered in both SKBr3 and another high erbB2-expressing cell line, BT474, by exposure to 1 micro M CP-654577, but this effect is not observed in MCF7 cells that express low erbB2. Levels of activated Akt, an important positive regulator of cell survival, are reduced within 2 h of exposure to 250 nM CP-654577, and this may contribute to the increased apoptosis. These biochemical effects are distinct from those produced by Tarceva, a selective EGFr inhibitor. The antitumor activity of CP-654577 was investigated in athymic mice bearing s.c. tumors from Fischer rat embryo fibroblasts transfected with erbB2. CP-654577 produced a dose-dependent reduction of p185(erbB2) autophosphorylation and inhibited the growth of these tumors. CP-654577 warrants further evaluation in tumors with high expression of p185(erbB2) and may differ from selective EGFr inhibitors or nonselective dual EGFr/erbB2 inhibitors in efficacy and therapeutic index.
Assuntos
Neoplasias da Mama/tratamento farmacológico , Inibidores Enzimáticos/farmacologia , Proteínas Serina-Treonina Quinases , Quinazolinas/farmacologia , Receptor ErbB-2/antagonistas & inibidores , Células 3T3 , Animais , Apoptose/efeitos dos fármacos , Neoplasias da Mama/enzimologia , Neoplasias da Mama/patologia , Ciclo Celular/efeitos dos fármacos , Divisão Celular/efeitos dos fármacos , Ativação Enzimática/efeitos dos fármacos , Cloridrato de Erlotinib , Feminino , Humanos , Camundongos , Camundongos Nus , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Fosforilação/efeitos dos fármacos , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas c-akt , Receptor ErbB-2/metabolismo , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Shoulder injuries in pediatric athletes are typically caused by acute or overuse injuries. The developing structures of the shoulder lead to injury patterns that are distinct from those of adult athletes. Overuse injuries often affect the physeal structures of the proximal humerus and can lead to pain and loss of sports participation. Shoulder instability is common in pediatric athletes, and recurrence is also a concern in this population. Fractures of the proximal humerus and clavicle are typically treated with conservative management, but there is a trend toward surgical intervention.
Assuntos
Atletas , Traumatismos em Atletas/epidemiologia , Lesões do Ombro/epidemiologia , Criança , Humanos , Incidência , Estados Unidos/epidemiologiaRESUMO
Slipped capital femoral epiphysis (SCFE) is a relatively common hip disorder often seen in overweight, peripubertal children. Although the exact etiology is uncertain, it is generally accepted that underlying endocrinopathies play a role in the pathogenesis. Hypothyroidism is the endocrine disorder cited most commonly in association with SCFE, and patients often have no history of thyroid dysfunction at the time of presentation. Despite being a well-recognized risk factor, recommendations for screening thyroid function in patients with typical presentations of SCFE have not been deemed cost-effective; however, there is data to support screening for hypothyroidism in patients with atypical presentations of SCFE or short stature. Hypothyroidism may have a significant impact on healing and bone union after surgical management of SCFE and there is a paucity of case reports in the literature describing potential peri- and postoperative complications. We performed a systematic review of the literature of all reported cases of SCFE with associated hypothyroidism using the search terms, which demonstrated a physiologic relationship between hypothyroidism and SCFE. Two case reports of SCFE in patients with hypothyroidism and associated complications are presented with the literature review. There is a physiologic relationship between thyroid dysfunction and SCFE, and we postulate that profound hypothyroidism may contribute to delayed healing or nonunion in patients undergoing operative management. We support the recommendation to screen patients with short stature, atypical presentation of SCFE, or perisistent nonunion after surgery. In cases of hypothyroidism, we recommend thyroid hormone replacement and laboratory confirmation of return to euthyroid state prior to operative intervention.