Role of Cyclooxygenase-2 in Head and Neck Tumorigenesis

The cyclooxygenase-2 (COX-2) is a potent enzyme that converts arachidonic acid to prostaglandins (PG), including PGE2, a key mediator of inflammation and angiogenesis. Importantly, COX-2 is activated in response to inflammatory stimuli, where it is also believed to promote the development and progression of head and neck cancers (HNC). COX-2 can mediate its protumorigenic effect through various mechanisms, such as inducing cell proliferation, inhibition of apoptosis, and suppressing the host’s immune response. Furthermore, COX-2 can induce the production of vascular endothelial growth factors, hence, promoting angiogenesis. Indeed, the ability of COX-2 inhibitors to selectively restrict the proliferation of tumor cells and mediating apoptosis provides promising therapeutic targets for cancer patients. Thus, in this comprehensive review, we summarized the reported differential expression patterns of COX-2 in different stages of head and neck carcinogenesis—from potentially premalignant lesions to invasive carcinomas. Furthermore, we examined the available meta-analysis evidence for COX-2 role in the carcinogenesis of HNC. Finally, further understanding of the biological processes of COX-2 and its role in orchestrating cell proliferation, apoptosis, and angiogenesis may give therapeutically beneficial insight to develop the management plan of HNC patients and improve their clinical outcomes.     

Localization of Function Within the Dorsal Hippocampus: The Role of the CA3 Subregion in Paired-Associate Learning.

Computational models and electrophysiological data suggest that the CA3 subregion of the hippocampus supports the formation of arbitrary associations; however, no behavioral studies have been conducted to test this hypothesis. Rats with neurotoxin-induced lesions of dorsal dentate gyrus (DG), CA3, or CA1 were tested on object-place and odor-place paired-associate tasks to test whether the mechanism that supports paired-associate learning is localized to the CA3 subregion of the dorsal hippocampus or whether all hippocampal subregions contribute to paired-associate learning. The data indicate that rats with DG or CA1 lesions learned the tasks as well as controls; however, CA3-lesioned rats were impaired in learning the tasks. Thus, the CA3 subregion of the dorsal hippocampus contains a mechanism to support paired-associate learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of Fimbria-Fornix, Hippocampus, and Amygdala Lesions on Discrimination Between Proximal Locations.

The conditioned cue preference (CCP) task was used to study the information required to discriminate between spatial locations defined by adjacent arms of an 8-arm radial maze. Normal rats learned the discrimination after 3 unreinforced preexposure (PE) sessions and 4 food paired-unpaired training trials. Fimbria-fornix lesions made before, but not after, PE, and hippocampus lesions made at either time, blocked the discrimination, suggesting that the 2 structures processed different information. Lateral amygdala lesions made before PE facilitated the discrimination. This amygdala-mediated interference with the discrimination was the result of a conditioned approach response that did not discriminate between the 2 arm locations. A hippocampus/fimbria-fornix system and an amygdala system process different information about the same learning situation simultaneously and in parallel. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Recovery of spatial alternation deficits following selective hippocampal destruction with kainic acid": Correction to Kesslak and Gage (1986).

Reports an error in "Recovery of spatial alternation deficits following selective hippocampal destruction with kainic acid" by J. Patrick Kesslak and Fred H. Gage (Behavioral Neuroscience, 1986[Apr], Vol 100[2], 280-283). In the aforementioned article, the degrees of freedom reported in the Results section are incorrect. In the sixth paragraph on page 281, the second sentence should read as follows: Results of the ANOVA indicated a significant effect for surgical treatments. F(2, 25)=25.44, p1986-21445-001.) Examined whether the sympathetic ingrowth of superior cervical ganglion (SCG) fibers sprouting into the hippocampus following kainic acid (KA) lesion of CA3 and CA4 pyramidal cells in male Sprague-Dawley rats would contribute to behavioral recovery. 31 Ss were trained on a forced-choice task. After reaching criterion performance levels, Ss received either KA (8 nM/0.4 μl) or saline injections into the hippocampus and were again tested on the forced-choice task. Half of the Ss had their SCG removed 35 days after injections, and all were again tested on the forced-choice task. Analysis of variance (ANOVA) showed Ss receiving KA took significantly longer to reach criterion following injections. Removal of the SCG after recovery reintroduced the performance deficit of KA-treated Ss on the alternation task; no other group showed any effect for SCG removal. Results indicate that the SCG may have a modulatory effect in behavioral recovery, although other mechanisms may also be operating. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Coupling image processing and stress analysis for damage identification in a human premolar tooth

Non-carious cervical lesions are characterized by the loss of dental hard tissue at the cement-enamel junction (CEJ). Exceeding stresses are therefore generated in the cervical region of the tooth that cause disruption of the bonds between the hydroxyapatite crystals, leading to crack formation and eventual loss of enamel and the underlying dentine.Damage identification was performed by image analysis techniques and allowed to quantitatively assess changes in teeth. A computerized two-step procedure was generated and applied to the first left maxillary human premolar. In the first step, dental images were digitally processed by a segmentation method in order to identify the damage. The considered morphological properties were the enamel thickness and total area, the number of fragments in which the enamel is chipped. The information retrieved by the data processing of the section images allowed to orient the stress investigation toward selected portions of the tooth. In the second step, a three-dimensional finite element model based on CT images of both the tooth and the periodontal ligament was employed to compare the changes occurring in the stress distributions in normal occlusion and malocclusion. The stress states were analyzed exclusively in the critical zones designated in the first step.The risk of failure at the CEJ and of crack initiation at the dentin-enamel junction through the quantification of first and third principal stresses, von Mises stress, and normal and tangential stresses, were also estimated.     

基于标记提取分水岭算法的医学图像分割

针对医学图像分割中分水岭算法的过分割问题,提出了一种改进的基于标记提取的分水岭算法．此算法埘分水岭算法进行厂两点改进：一是在预处理阶段,先对原始图像做腐蚀滤波和膨胀滤波处理,将原始吲像与腐蚀图像相加后减去膨胀图像得到合并图像,再对合并图像做开、闭运算,从而达到滤除原始图像中的噪声和非感知信息、保留原始图像结构信息的目的;二是在分割阶段,对开、闭运算后的图像进行分水岭分割,该分割由形态梯度计算、标记提取和分水岭分割二部分组成．改进后的算法因为无需进行分割后的区域合并处理,降低了分割的复杂性,同时能较好地抑制慨部医学图像中的过分割问题,并把图像中的病变区域有效分割出来．     

The influence of hippocampal lesions on the discrimination of structure and on spatial memory in pigeons (Columba livia).

Pigeons (Columba livia) were trained with a spatial structural discrimination, which was based on the spatial relationship among the components of a pattern, and a feature-binding structural discrimination, which was based on how different visual features within a pattern were combined. Neither discrimination was impaired by damage to the hippocampus and area parahippocampalis. The lesions impaired performance on a spatial working memory and a spatial reference memory task in open field. The results indicate an intact hippocampus is not essential for the solution of structural discriminations in pigeons and the hippocampus is important for processing some types of spatial information--that used in navigation, but not other types--that used in spatial structural discriminations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Involvement of Ventral Pallidum in Prefrontal Cortex-Dependent Aspects of Spatial Working Memory.

Ventral pallidum (VP) is an important source of limbic input to medial thalamus. Three studies examined the role of VP in spatial memory tasks impaired by medial thalamic lesions. In the 1st study, rats with VP lesions were impaired performing delayed matching trained with retractable levers (DMRL), a measure sensitive to prefrontal (but not hippocampal) damage. The 2nd study demonstrated dose-dependent DMRL impairment following microinjection of gamma-aminobutyric acidA, glutamate, or mu-opioid agonists in VP. In the 3rd study, VP lesions had no effect on varying choice radial-maze delayed nonmatching, a measure sensitive to hippocampal (but not prefrontal) lesions. These results suggest a common role in spatial memory for VP and other components of prefrontal-ventral striatopallidothalamic circuits distinct from hippocampal function. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential Fos Expression Following Aspiration, Electrolytic, or Excitotoxic Lesions of the Perirhinal Cortex in Rats.

The authors explored the possibility that there are different neural consequences, beyond the primary site of brain damage, following perirhinal cortex (PRh) lesions made in different ways. Fos expression was used as a marker for neuronal activation and compared across the forebrains of rats that underwent the different types of surgery. Electrolytic and excitotoxic PRh lesions produced dramatic increases in Fos expression in the cortex, and excitotoxic and aspiration PRh lesions increased Fos expression in the dentate gyrus. These data are consistent with the hypothesis that different lesion methods have separable effects on neural function in regions outside the lesion site that could account for inconsistencies in the literature regarding the behavioral effects of PRh lesions on tests of spatial memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Effects of Hippocampal Lesions on Response, Direction, and Place Learning in Rats.

Rats with hippocampal or sham lesions were trained to find food on a T maze located at 2 positions. Response rats were required to make a right or left turn. Direction rats were required to go in a consistent direction (east or west). Place rats were required to go to a consistent location, relative to room cues. One place group had distinguishable start points at the 2 maze positions, whereas another place group had start points facing the same side of the room. Controls took longer to solve a place problem than the response and direction problems when the start points were not distinguishable. Rats with hippocampal lesions were not different than controls on the response problem but were impaired on the direction and place problems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)