Mechanisms of Nausea and Vomiting: Current Knowledge and Recent Advances in Intracellular Emetic Signaling Systems

Nausea and vomiting are common gastrointestinal complaints that can be triggered by diverse emetic stimuli through central and/or peripheral nervous systems. Both nausea and vomiting are considered as defense mechanisms when threatening toxins/drugs/bacteria/viruses/fungi enter the body either via the enteral (e.g., the gastrointestinal tract) or parenteral routes, including the blood, skin, and respiratory systems. While vomiting is the act of forceful removal of gastrointestinal contents, nausea is believed to be a subjective sensation that is more difficult to study in nonhuman species. In this review, the authors discuss the anatomical structures, neurotransmitters/mediators, and corresponding receptors, as well as intracellular emetic signaling pathways involved in the processes of nausea and vomiting in diverse animal models as well as humans. While blockade of emetic receptors in the prevention of vomiting is fairly well understood, the potential of new classes of antiemetics altering postreceptor signal transduction mechanisms is currently evolving, which is also reviewed. Finally, future directions within the field will be discussed in terms of important questions that remain to be resolved and advances in technology that may help provide potential answers.     

Distribution of nitric oxide synthase immunoreactivity in the mouse brain

Nitric oxide (NO) is a gaseous intercellular messenger with a wide range of neural functions. NO is synthesized by activation of different isoforms of nitric oxide synthases (NOS). At present NOS immunoreactivity has been described in mouse brain in restricted and definite areas and no detailed mapping studies have yet been reported for NOS immunoreactivity. We have studied the distribution of neuronal NOS-containing neurons in the brain of three months male mice, using a specific commercial polyclonal antibody against the neuronal isoform of nitric oxide synthase (nNOS). Neuronal cell bodies exhibiting nNOS immunoreactivity were found in several distinct nuclei throughout the brain. The neurons that were positively stained exhibited different intensities of reaction. In some brain areas (i.e., cortex, striatum, tegmental nuclei) neurons were intensely stained in a Golgi-like fashion. In other regions, immunoreactive cells are moderately stained (i.e., magnocellular nucleus of the posterior commissure, amygdaloid nucleus, interpeduncular nucleus, lateral periaqueductal gray) or weakly stained (i.e., vascular organ of the lamina terminalis, hippocampus, inferior colliculus, reticular nucleus). In the mouse, the NO-producing system appears well developed and widely diffused. In particular, nNOS immunoreactive neurons seem chiefly present in several sensory pathways like all the nuclei of the olfactory system, as well as in many regions of the lymbic system. These data suggest a widespread role for the NO system in the mouse nervous system.     

听觉诱发电位信号的小波消噪方法研究

本文对听觉诱发电位(auditory brainstem response,ABR)的信号消噪方法进行研究,采用Daubechies5(DB5)小波分析方法进行去噪处理。首先在MATLAB中对信号进行频谱分析,然后再利用小波工具箱找到DB5是适合于分析ABR信号的最优小波基,结合频谱分析结果提出小波系数的选取算法。研究表明选用DB5小波对测量信号进行变换处理,该分析方法不仅大大减少了叠加次数,同时也得到了更好的去噪效果。最后,在程序中实现了上述小波消噪算法,并依照临床感兴趣的Ⅰ-Ⅴ五波的波间潜伏期设计出波形评估程序,从而进一步证实了上述理论的可靠性。     

Stress Adaptation and the Brainstem with Focus on Corticotropin-Releasing Hormone

Stress adaptation is of utmost importance for the maintenance of homeostasis and, therefore, of life itself. The prevalence of stress-related disorders is increasing, emphasizing the importance of exploratory research on stress adaptation. Two major regulatory pathways exist: the hypothalamic–pituitary–adrenocortical axis and the sympathetic adrenomedullary axis. They act in unison, ensured by the enormous bidirectional connection between their centers, the paraventricular nucleus of the hypothalamus (PVN), and the brainstem monoaminergic cell groups, respectively. PVN and especially their corticotropin-releasing hormone (CRH) producing neurons are considered to be the centrum of stress regulation. However, the brainstem seems to be equally important. Therefore, we aimed to summarize the present knowledge on the role of classical neurotransmitters of the brainstem (GABA, glutamate as well as serotonin, noradrenaline, adrenaline, and dopamine) in stress adaptation. Neuropeptides, including CRH, might be co-localized in the brainstem nuclei. Here we focused on CRH as its role in stress regulation is well-known and widely accepted and other CRH neurons scattered along the brain may also complement the function of the PVN. Although CRH-positive cells are present on some parts of the brainstem, sometimes even in comparable amounts as in the PVN, not much is known about their contribution to stress adaptation. Based on the role of the Barrington’s nucleus in micturition and the inferior olivary complex in the regulation of fine motoric—as the main CRH-containing brainstem areas—we might assume that these areas regulate stress-induced urination and locomotion, respectively. Further studies are necessary for the field.     

Tinnitus and Hearing Loss in Hamsters (Mesocricetus auratus) Exposed to Loud Sound.

Hamsters were trained to go left and right to sounds on their left and right sides, respectively. Silent trials were occasionally given in which no sound was presented. Hamsters exposed to a loud 2- or 10-kHz tone in 1 ear often shifted their responding on the silent trials to the side of the exposed ear, suggesting that they perceived a sound in that ear (i.e., tinnitus). The degree of tinnitus was related to the degree of the accompanying hearing loss (estimated by the auditory brainstem response). However, a conductive hearing loss (plugging 1 ear) did not cause a hamster to test positive for tinnitus. Tinnitus could be demonstrated within minutes following tone exposure, indicating an immediate onset, as occurs in humans. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The sleep-like nature of early mammalian behavioral rhythms: Theoretical comment on Todd et al. (2010).

Early sleep patterns lack several of the major defining physiological criteria used to identify sleep states in adult animals, but many typical aspects of mature sleep can nevertheless be demonstrated at surprisingly early stages of development. In Todd, Gibson, Shaw, & Blumberg (2010), the ability to compensate for enforced sleep deprivation is found to be present already shortly after birth in laboratory rats, an altricial mammalian species. Whereas the brainstem is capable of resisting enforced wakefulness by an increasing “pressure” to fall asleep, “catch-up” replacement of the lost sleep by means of longer subsequent sleep durations requires forebrain participation. This investigation represents an initial foray into the theoretically important area of the ontogeny of homeostatic regulatory mechanisms for behaviorally crucial neurophysiological processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Gamma Knife Treatment of Brainstem Metastases

The management of brainstem metastases is challenging. Surgical treatment is usually not an option, and chemotherapy is of limited utility. Stereotactic radiosurgery has emerged as a promising palliative treatment modality in these cases. The goal of this study is to assess our single institution experience treating brainstem metastases with Gamma Knife radiosurgery (GKRS). This retrospective chart review studied 41 patients with brainstem metastases treated with GKRS. The most common primary tumors were lung, breast, renal cell carcinoma, and melanoma. Median age at initial treatment was 59 years. Nineteen (46%) of the patients received whole brain radiation therapy (WBRT) prior to or concurrent with GKRS treatment. Thirty (73%) of the patients had a single brainstem metastasis. The average GKRS dose was 17 Gy. Post-GKRS overall survival at six months was 42%, at 12 months was 22%, and at 24 months was 13%. Local tumor control was achieved in 91% of patients, and there was one patient who had a fatal brain hemorrhage after treatment. Karnofsky performance score (KPS) >80 and the absence of prior WBRT were predictors for improved survival on multivariate analysis (HR 0.60 (p = 0.02), and HR 0.28 (p = 0.02), respectively). GKRS was an effective treatment for brainstem metastases, with excellent local tumor control.     

Infant temperament and the brainstem auditory evoked response in later childhood.

Brainstern auditory evoked responses (BAERs) were evaluated on 10–12-year-old children (N?=?56) who had been classified as high or low reactive to unfamiliar stimuli at 4 months of age. BAER measurement was selected because high reactive infants tend to become inhibited or fearful young children, and adult introverts have a faster latency to wave V of the BAER than do extroverts. Children previously classified as high reactive at 4 months had larger wave V components than did low reactive children, a finding that possibly suggests greater excitability in projections to the inferior cofliculus. The fact that a fundamental feature of brainstem activity differentiated preadolescent children belonging to two early temperamental groups supports the value of gathering physiological data in temperament research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

基于模板缩放的小脑与脑干组织的图像分割

提出了一种基于模板缩放的分割方法,用于数字人切片图像中小脑与脑干组织的分割.算法首先将图像序列分段.通过在每一段中采用边缘检测的方法获得单张分割模板,然后进行形态学运算控制模板缩放实现图像的连续自动分割.实验结果表明,该算法的分割结果与图像分割的"金标准"符合很好,分割相似指数(DSI)大于70%,且分割效率高,有助于...