The importance of context: when relative relief renders pain pleasant

Context can influence the experience of any event. For instance, the thought that "it could be worse" can improve feelings towards a present misfortune. In this study we measured hedonic feelings, skin conductance, and brain activation patterns in 16 healthy volunteers who experienced moderate pain in two different contexts. In the "relative relief context," moderate pain represented the best outcome, since the alternative outcome was intense pain. However, in the control context, moderate pain represented the worst outcome and elicited negative hedonic feelings. The context manipulation resulted in a "hedonic flip," such that moderate pain elicited positive hedonics in the relative relief context. Somewhat surprisingly, moderate pain was even rated as pleasant in this context, despite being reported as painful in the control context. This "hedonic flip" was corroborated by physiological and functional neuroimaging data. When moderate pain was perceived as pleasant, skin conductance and activity in insula and dorsal anterior cingulate were significantly attenuated relative to the control moderate stimulus. "Pleasant pain" also increased activity in reward and valuation circuitry, including the medial orbitofrontal and ventromedial prefrontal cortices. Furthermore, the change in outcome hedonics correlated with activity in the periacqueductal grey (PAG) of the descending pain modulatory system (DPMS). The context manipulation also significantly increased functional connectivity between reward circuitry and the PAG, consistent with a functional change of the DPMS due to the altered motivational state. The findings of this study point to a role for brainstem and reward circuitry in a context-induced "hedonic flip" of pain.

Baseline reward circuitry activity and trait reward responsiveness predict expression of opioid analgesia in healthy subjects

Variability in opioid analgesia has been attributed to many factors. For example, genetic variability of the μ-opioid receptor (MOR)-encoding gene introduces variability in MOR function and endogenous opioid neurotransmission. Emerging evidence suggests that personality trait related to the experience of reward is linked to endogenous opioid neurotransmission. We hypothesized that opioid-induced behavioral analgesia would be predicted by the trait reward responsiveness (RWR) and the response of the brain reward circuitry to noxious stimuli at baseline before opioid administration. In healthy volunteers using functional magnetic resonance imaging and the μ-opioid agonist remifentanil, we found that the magnitude of behavioral opioid analgesia is positively correlated with the trait RWR and predicted by the neuronal response to painful noxious stimuli before infusion in key structures of the reward circuitry, such as the orbitofrontal cortex, nucleus accumbens, and the ventral tegmental area. These findings highlight the role of the brain reward circuitry in the expression of behavioral opioid analgesia. We also show a positive correlation between behavioral opioid analgesia and opioid-induced suppression of neuronal responses to noxious stimuli in key structures of the descending pain modulatory system (amygdala, periaqueductal gray, and rostral-ventromedial medulla), as well as the hippocampus. Further, these activity changes were predicted by the preinfusion period neuronal response to noxious stimuli within the ventral tegmentum. These results support the notion of future imaging-based subject-stratification paradigms that can guide therapeutic decisions.

Polymorphous low grade adenocarcinoma of the parotid gland: A case report with cytohistological correlation and its immunohistochemical study

Polymorphous low-grade adenocarcinoma is a rare salivary gland malignant tumor of low aggressiveness, commonly occurring in minor salivary glands. Its origin in major salivary glands is considered exceedingly rare. We report a case of polymorphous low grade adenocarcinoma arising from left parotid in a 21-yearold female patient.Journal of Pathology of Nepal (2012) Vol. 2, 331-334DOI: http://dx.doi.org/10.3126/jpn.v2i4.6890

Histological pattern of esophageal cancer at BP Koirala memorial cancer hospital in Nepal: a three year retrospective study

Background: The incidence of esophageal adenocarcinoma is increasing in trends. Squamous cell carcinoma is associated with tobacco and alcohol consumption. Adenocarcinoma is often associated with a history of gastroesophageal reflux disease and Barrett's esophagus. The aim of this study was to find out the histological pattern of esophageal cancer in one of the largest Cancer center in Nepal.Materials and Methods: Between January 2008 and December 2011, a total of 106 cases of esophageal cancer were received in the department of pathology, BP Koirala Memorial Cancer Hospital. Relevant clinical data were retrieved from computer database of the hospital.Results: A total of 106 cases of esophageal carcinomas were diagnosed during a three years period. There were 68 (64.15%) cases of squamous cell carcinoma, 33 (31.13%) cases of adenocarcinoma including signet ring cell carcinoma, 4 (3.76%) cases of undifferentiated carcinoma and 1 (0.94%) case of small cell carcinoma. The esophageal cancer was most common in the age group of 61-70 years of age. Distal third of esophagus was the most common site for esophageal carcinoma, followed by middle esophagus and proximal esophagus.Conclusion: The most frequent type of esophageal carcinoma is squamous cell carcinoma followed by adenocarcinoma. Distal esophagus is the most common site with male preponderance.Journal of Pathology of Nepal (2012) Vol. 2, 277-281DOI: http://dx.doi.org/10.3126/jpn.v2i4.6877

P5-11-14: Flat Epithelial Atypia of the Breast: A Single Institution Experience

Background: Flat epithelial atypia of the breast is a relatively new entity of unknown significance. Our objective is to evaluate our surgical experience with this diagnosis.

Methods: A single institution database of breast patients from 2005–2010 was used to identify women who were diagnosed with flat epithelial atypia on core biopsy and subsequently underwent surgical excision. Patient data regarding history, type and reason for biopsy, and associated pathology was collected. Individuals diagnosed with flat epithelia atypia and cancer on core biopsies in the same breast were excluded.

Results: There were 52 patients who underwent surgical excision for the primary diagnosis of flat epithelial atypia. There were 3 (6%) patients with a personal history of breast cancer, 14 (27%) patients with a family history of breast cancer, and 11 (21%) patients with a concurrent new diagnosis of breast cancer in the contralateral breast. Core biopsy was recommended in most (81%) cases because of suspicious calcifications on mammography. Twenty-eight (54%) patients were found to have flat epithelial atypia associated with other atypical breast hyperplasia and 24 (46%) had flat epithelial atypia as the most significant lesion on core biopsy. In 8 (15%) patients, there was a sonographic correlate that was biopsied; 5 had only flat epithelial atypia and 3 had flat epithelial atypia associated with other atypical hyperplasia. Of the 52 patients there were 4 (8%) patients who upstaged to ductal carcinoma in-situ on surgical excision. There were no cases of invasive carcinoma. All ductal carcinoma in-situ cases were associated with other atypical breast hyperplasia, not flat epithelial atypia alone.

Conclusion: Though flat epithelial atypia may be associated with an increased risk of breast cancer, surgical excision of pure flat epithelial atypia may not be necessary. Larger studies are needed to corroborate these findings.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-11-14.

The effect of treatment expectation on drug efficacy: imaging the analgesic benefit of the opioid remifentanil

Evidence from behavioral and self-reported data suggests that the patients' beliefs and expectations can shape both therapeutic and adverse effects of any given drug. We investigated how divergent expectancies alter the analgesic efficacy of a potent opioid in healthy volunteers by using brain imaging. The effect of a fixed concentration of the μ-opioid agonist remifentanil on constant heat pain was assessed under three experimental conditions using a within-subject design: with no expectation of analgesia, with expectancy of a positive analgesic effect, and with negative expectancy of analgesia (that is, expectation of hyperalgesia or exacerbation of pain). We used functional magnetic resonance imaging to record brain activity to corroborate the effects of expectations on the analgesic efficacy of the opioid and to elucidate the underlying neural mechanisms. Positive treatment expectancy substantially enhanced (doubled) the analgesic benefit of remifentanil. In contrast, negative treatment expectancy abolished remifentanil analgesia. These subjective effects were substantiated by significant changes in the neural activity in brain regions involved with the coding of pain intensity. The positive expectancy effects were associated with activity in the endogenous pain modulatory system, and the negative expectancy effects with activity in the hippocampus. On the basis of subjective and objective evidence, we contend that an individual's expectation of a drug's effect critically influences its therapeutic efficacy and that regulatory brain mechanisms differ as a function of expectancy. We propose that it may be necessary to integrate patients' beliefs and expectations into drug treatment regimes alongside traditional considerations in order to optimize treatment outcomes.

A multisensory investigation of the functional significance of the "pain matrix"

Functional neuroimaging studies in humans have shown that nociceptive stimuli elicit activity in a wide network of cortical areas commonly labeled as the "pain matrix" and thought to be preferentially involved in the perception of pain. Despite the fact that this "pain matrix" has been used extensively to build models of where and how nociception is processed in the human brain, convincing experimental evidence demonstrating that this network is specifically related to nociception is lacking. The aim of the present study was to determine whether there is at least a subset of the "pain matrix" that responds uniquely to nociceptive somatosensory stimulation. In a first experiment, we compared the fMRI brain responses elicited by a random sequence of brief nociceptive somatosensory, non-nociceptive somatosensory, auditory and visual stimuli, all presented within a similar attentional context. We found that the fMRI responses triggered by nociceptive stimuli can be largely explained by a combination of (1) multimodal neural activities (i.e., activities elicited by all stimuli regardless of sensory modality) and (2) somatosensory-specific but not nociceptive-specific neural activities (i.e., activities elicited by both nociceptive and non-nociceptive somatosensory stimuli). The magnitude of multimodal activities correlated significantly with the perceived saliency of the stimulus. In a second experiment, we compared these multimodal activities to the fMRI responses elicited by auditory stimuli presented using an oddball paradigm. We found that the spatial distribution of the responses elicited by novel non-target and novel target auditory stimuli resembled closely that of the multimodal responses identified in the first experiment. Taken together, these findings suggest that the largest part of the fMRI responses elicited by phasic nociceptive stimuli reflects non nociceptive-specific cognitive processes.

Flexible cerebral connectivity patterns subserve contextual modulations of pain

The perception of pain can be significantly modulated by the behavioral context. Here, we investigated how contextual modulations of pain are subserved in the human brain. We independently modulated the attentional and emotional context of painful stimuli and recorded brain activity by using functional magnetic resonance imaging. Our results confirm that attention to pain and a negative emotional context increases pain perception and this is concomitantly associated with increased neural activity in the anterior insular cortex. Connectivity analyses further reveal that during attentional and emotional modulations of pain, the anterior insula selectively and flexibly connects to attentional and emotional brain networks in frontoparietal and medial temporal lobe areas, respectively. We conclude that the flexible functional connectivity of the anterior insula to other functional systems of the brain, for example, attentional and emotional brain networks, subserves the extraordinary sensitivity of the pain experience to contextual modulations.

Unravelling the mystery of pain, suffering, and relief with brain imaging

In humans, the experience of pain and suffering is conveyed specifically by language. Noninvasive neuroimaging techniques now provide an account of neural activity in the human brain when pain is experienced. Knowledge gleaned from neuroimaging experiments has shaped contemporaneous accounts of pain. Within the biopsychosocial framework, nociception is undoubtedly required for survival, but is neither necessary nor sufficient for the consciousness of pain in humans. Pain emerges from the brain, which also exerts a top-down influence on nociception. In the brains of patients with chronic pain, neuroimaging has revealed subtle but significant structural, functional, and neurochemical abnormalities. Converging evidence suggests that the chronic pain state may arise from dysfunction of the frontal-limbic system. Further research in the clinical pain population will continue to identify neural mechanisms that contribute to the experience and consequence of pain, which may then be targeted therapeutically.

Computer-aided diagnosis of pulmonary nodules using a two-step approach for feature selection and classifier ensemble construction

OBJECTIVE

Accurate classification methods are critical in computer-aided diagnosis (CADx) and other clinical decision support systems. Previous research has reported on methods for combining genetic algorithm (GA) feature selection with ensemble classifier systems in an effort to increase classification accuracy. In this study, we describe a CADx system for pulmonary nodules using a two-step supervised learning system combining a GA with the random subspace method (RSM), with the aim of exploring algorithm design parameters and demonstrating improved classification performance over either the GA or RSM-based ensembles alone.

METHODS AND MATERIALS

We used a retrospective database of 125 pulmonary nodules (63 benign; 62 malignant) with CT volumes and clinical history. A total of 216 features were derived from the segmented image data and clinical history. Ensemble classifiers using RSM or GA-based feature selection were constructed and tested via leave-one-out validation with feature selection and classifier training executed within each iteration. We further tested a two-step approach using a GA ensemble to first assess the relevance of the features, and then using this information to control feature selection during a subsequent RSM step. The base classification was performed using linear discriminant analysis (LDA).

RESULTS

The RSM classifier alone achieved a maximum leave-one-out Az of 0.866 (95% confidence interval: 0.794-0.919) at a subset size of s=36 features. The GA ensemble yielded an Az of 0.851 (0.775-0.907). The proposed two-step algorithm produced a maximum Az value of 0.889 (0.823-0.936) when the GA ensemble was used to completely remove less relevant features from the second RSM step, with similar results obtained when the GA-LDA results were used to reduce but not eliminate the occurrence of certain features. After accounting for correlations in the data, the leave-one-out Az in the two-step method was significantly higher than in the RSM and the GA-LDA.

CONCLUSIONS

We have developed a CADx system for evaluation of pulmonary nodule based on a two-step feature selection and ensemble classifier algorithm. We have shown that by combining classifier ensemble algorithms in this two-step manner, it is possible to predict the malignancy for solitary pulmonary nodules with a performance exceeding that of either of the individual steps.

Quantitative analysis of spatial distortions of diffusion techniques at 3T

Diffusion has been widely adopted in the clinical setting to study the microstructural tissue changes in conjunction with anatomic imaging and metabolic imaging to offer insights on the status of the tissue injury or lesion. However, geometric distortions caused by magnetic susceptibility effects, eddy currents and gradient imperfections greatly affect the clinical utility of the diffusion images. Several diffusion methods have been proposed in the recent years to obtain diffusion parameters with increased accuracy. In most cases, the comparisons to the clinical standard echo-planar imaging (EPI) diffusion are done visually without quantitative measurements. In this study, we present three simple, complementary quantitative methods of nonrigid image registration and shape analyses for evaluating spatial distortions on magnetic resonance images with application in comparing single-shot fast spin-echo (SSFSE) and EPI based diffusion measurements. These methods have confirmed the SSFSE based diffusion method is less distorted than the EPI based one, which is generally accepted through visual inspection.

The structural and optical properties of InN nanodots grown with various V/III ratios by metal-organic chemical vapor deposition

Self-assembled InN nanodots have been prepared at 650 degrees C with various V/III ratios from 500 to 30 000 by metal-organic chemical vapor deposition (MOCVD). It is found that the dot density and morphological size as well as the optical properties all display drastic changes at V/III = 12 000. Generally, denser and smaller InN nanodots with higher emission energy and narrower linewidth were obtained when growth was conducted at V/III ratios slightly lower than 12 000 as compared to those at higher V/III ratios. The physical properties of our MOCVD-grown InN nanodots are sensitive to the surface structure and the morphology is very similar to molecular beam epitaxially grown GaN and InN films, which may be used as a guide to optimize the InN growth.

The effects of age and aboriginality on the incidence of low birth weight in mountain townships of Taiwan

BACKGROUND

This study aimed to examine the associations between aboriginality, age, demographic and socioeconomic factors of the mother and the risk of low birth weight (LBW) in mountain townships of Taiwan.

METHODS

We analyzed the LBW proportion of single live babies born to 2032 first-time mothers between 2004 and 2005. Data were analyzed using the chi-square test, analysis of variance, the Scheffe test and logistic regression.

RESULTS

About 14.8% of Aboriginal mothers and 18.7% of Aboriginal teen mothers gave birth to infants of LBW. Aboriginal mothers were found to be at higher risk of delivering LBW infants; however, after controlling for marital status and education, the influence of aboriginality and age was no longer significant.

CONCLUSIONS

Marital status and education are more important determinants of LBW than aboriginality and age in mountain townships of Taiwan.

Enterolith causing afferent loop obstruction: a case report and literature review

Enterolith formation is a rare cause of afferent limb obstruction following Billroth II gastrectomy and Roux-en-Y hepaticojejunostomy surgery. A case of ascending cholangitis caused by an enterolith incarcerated in the afferent loop of a 15-year-old Roux-en-Y hepaticojejunostomy was emergently decompressed under direct ultrasound guidance prior to surgery. This is the thirteenth reported case of an enterolith causing afferent loop obstruction. A discussion of our management approach and a review of the relevant literature are presented.

Analysis of the UCHL1 genetic variant in Parkinson's disease among Chinese

The inverse association of the functional ubiquitin carboxy-terminal hydrolase L1 (UCHL1) S18Y variant with Parkinson's disease (PD) among Caucasian populations has been debated. We conducted a large-scale analysis to investigate the age-of-onset effect of the UCHL1 variant in PD among ethnic Chinese. Individual data sets from 5 centers comprising a total of 4088 study subjects were analyzed. In the univariate analysis, only data from 1 center showed a trend towards a protective effect among young subjects. However, in the combined analysis, no significant association between the UCHL1 variant and PD was detected (A allele frequency 0.531 vs. 0.528, p=0.87, OR 1.01, 95% CI 0.92-1.1). Among subjects less than 60 years old, the OR is 0.99 (95% CI 0.84-1.16, p=0.88). A multivariate logistic regression analysis showed that family history, UCHL1 variant and the interaction of UCHL1 variant and age at onset (p=0.816) were not significantly associated with PD.