Effects of smoking on thermal pain threshold in deprived and minimally-deprived habitual smokers

Modulation of Brain Network Topological Properties in Knee Osteoarthritis by Electroacupuncture in Rats

Introduction

Osteoarthritis is a chronic, ongoing disease that affects patients, and pain is considered a key factor affecting patients, but the brain changes during the development of osteoarthritis pain are currently unclear. In this study, we used electroacupuncture (EA) to intervene the rat model of knee osteoarthritis and analyzed the changes in topological properties of brain networks using graph theory.

Methods

Sixteen SD rat models of right-knee osteoarthritis with anterior cruciate ligament transection (ACLT) were randomly divided into electroacupuncture intervention group and control group. The electroacupuncture group was intervened on Zusanli (ST36) and Futu (ST32) for 20 min each time, five times a week for 3 weeks, while the control group was applied sham stimulation. Both groups were measured for pain threshold. The small-world properties and node properties of the brain network between the two groups after the intervention were statistically analyzed by graph theory methods.

Results

The differences are mainly in the changes in node attributes between the two groups, such as degree centrality, betweenness centrality, and so on in different brain regions (P<0.05). Both groups showed no small-world characteristics in the brain networks of the two groups. The mechanical thresholds and thermal pain thresholds were significantly higher in the EA group than in the control group (P<0.05).

Conclusion

The study demonstrated that electroacupuncture intervention enhanced the activity of nodes related to pain circuit and relieved pain in osteoarthritis, which provides a complementary basis for explaining the effect of electroacupuncture intervention on pain through graphical analysis of changes in brain network topological properties and helps to develop an imaging model for pain affected by electroacupuncture.

Sinomenine alleviates dorsal root ganglia inflammation to inhibit neuropathic pain via the p38 MAPK/CREB signalling pathway

The objective of study was to investigate the inhibitory effect of sinomenine on neuropathic pain on dorsal root ganglia (DRG). The DRG cell line and spinal nerve ligation (SNL) model were used in this study. The effect of sinomenine on the cell viability was examined by MTT assay. The expression of p38 MAPK, NF-κB, c-fos, SP and TNF-α was detected by using immunofluorescence and immunohistochemistry assay. We also assessed the level of p-CaMKII, COX-2, p-CREB, IL-17A, TLR4 and IL-1β via western blotting and RT-qPCR. Compared to the controls, sinomenine showed a protective effect on TNF-α-induced apoptosis on DRG cells in a dose-dependent manner, with an increase of cell viability and a decrease of reactive oxygen species level as well as LDH release. Parallelly, sinomenine treatment significantly reduced the expression of various factors related to stress and inflammation, including p38 MAPK, NF-κB, c-fos, p-CAMKII, COX-2, p-CREB, TLR4 and IL-17A in DRG cells in vitro. Furthermore, we found that administration of sinomenine significantly reduced mechanical withdrawal threshold and thermal withdrawal latency and inhibited the inflammation and activation of p38 signaling in SNL rats. It is noting that combined therapy of sinomenine and pulsed radiofrequency exhibited higher efficacy of dorsal root ganglia inflammation than single treatment as well as the combination of oxycodone and pulsed radiofrequency. Sinomenine inhibited the apoptosis of DRG cell by regulating p38 MAPK/CREB signalling pathway, which provides evidence to alleviate neuropathic pain in clinic.

Association between physical activity and pain processing in adults with chronic low back pain compared to pain-free controls

BACKGROUND

Pain sensitivity has been negatively associated with physical activity levels. Few studies have examined associations between experimentally induced pain sensitivity and physical activity in adults with chronic low back pain and pain-free controls.

OBJECTIVE

The objective of this study was to examine associations between physical activity levels and how an individual processes pain using experimentally induced pain stimuli.

METHODS

Seventy subjects (CLBP = 49; mean age = 46.8 ± 14.9; Pain-free = 21; mean age = 45.3 ± 18.2, n of females = 46) participated. A self-report questionnaire derived from the International Physical Activity Questionnaire (IPAQ) was used to calculate an activity level index. Pain sensitivity was assessed via quantitative sensory testing (QST) at the right lower extremity.

RESULTS

Moderate (U = 688, p< 0.05) and vigorous (U = 649, p< 0.05) physical activity levels were higher in pain-free vs. individuals with CLBP. Activity level was not associated with pain sensitivity (Pain-free: R2 = 0.02, p> 0.05; CLBP: R2 = 0.01, p> 0.05). Both moderate (R2 = 0.49, p< 0.05) and vigorous (R2 = 0.68, p< 0.01) physical activity were associated with pain modulation amongst pain-free individuals.

CONCLUSIONS

Findings suggest that physical activity influences pain modulation amongst pain-free individuals, however no relationship exists once CLBP is present. However, future investigation will elucidate the extent to which physical activity level either prevents CLBP or is effective in alleviating CLBP.

Assessment of pain in adolescents: Influence of gender, smoking status and tobacco abstinence

PURPOSE

We examined sex differences between smokers and nonsmokers in pain threshold, tolerance, and intensity and the effect of pain on cardiovascular measures, withdrawal, and craving during acute smoking abstinence.

METHODS

Ninety-six (53 smokers, 43 nonsmokers) adolescents completed the Cold Pressor Task (CPT) to assess pain responses after minimal (1h) and 42-hour smoking deprivation. Vital signs and craving were assessed before and after CPT completion.

RESULTS

Smokers, compared to nonsmokers, had significantly lower pain tolerance (p<0.01) and pain threshold (p<0.001). Female smokers had significantly lower pain tolerance prior to, and following, 42-hour deprivation compared to male smokers (p's<0.01), male nonsmokers (p's<0.01), and female nonsmokers (p's<0.001), while male smokers demonstrated significantly decreased pain tolerance following 42-hour deprivation (p<0.05). Additionally, during minimal deprivation, at time of hand removal, female smokers had higher pain intensity compared to female nonsmokers (p<0.05) and male smokers (p<0.01). Withdrawal was not significantly correlated with any CPT measures or subjective pain during or following minimal deprivation or acute abstinence. Craving was associated with pain 15s after hand submersion (p=0.007) at 42-hour deprivation.

CONCLUSIONS

Smokers had a lower pain threshold than non-smokers, with female smokers demonstrating lower pain tolerance during minimal deprivation than all comparison groups, and, continuing to have diminished pain tolerance compared to female nonsmokers following 42h of abstinence. Male smokers demonstrated tobacco-deprivation-induced reductions in pain tolerance. Further study of pain-related factors that may contribute to relapse and maintenance of smoking behaviors, and mechanisms of these relationships among adolescent smokers is warranted.

Pressure and cold pain threshold reference values in a large, young adult, pain-free population

Background and aims

Currently there is a lack of large population studies that have investigated pain sensitivity distributions in healthy pain free people. The aims of this study were: (1) to provide sex-specific reference values of pressure and cold pain thresholds in young pain-free adults; (2) to examine the association of potential correlates of pain sensitivity with pain threshold values.

Methods

This study investigated sex specific pressure and cold pain threshold estimates for young pain free adults aged 21–24 years. A cross-sectional design was utilised using participants (n =617) from the Western Australian Pregnancy Cohort (Raine) Study at the 22-year follow-up. The association of site, sex, height, weight, smoking, health related quality oflife, psychological measures and activity with pain threshold values was examined. Pressure pain threshold (lumbar spine, tibialis anterior, neck and dorsal wrist) and cold pain threshold (dorsal wrist) were assessed using standardised quantitative sensory testing protocols.

Results

Reference values for pressure pain threshold (four body sites) stratified by sex and site, and cold pain threshold (dorsal wrist) stratified by sex are provided. Statistically significant, independent correlates of increased pressure pain sensitivity measures were site (neck, dorsal wrist), sex (female), higher waist-hip ratio and poorer mental health. Statistically significant, independent correlates of increased cold pain sensitivity measures were, sex (female), poorer mental health and smoking.

Conclusions

These data provide the most comprehensive and robust sex specific reference values for pressure pain threshold specific to four body sites and cold pain threshold at the dorsal wrist for young adults aged 21–24 years. Establishing normative values in this young age group is important given that the transition from adolescence to adulthood is a critical temporal period during which trajectories for persistent pain can be established.

Implications

These data will provide an important research resource to enable more accurate profiling and interpretation of pain sensitivity in clinical pain disorders in young adults. The robust and comprehensive data can assist interpretation of future clinical pain studies and provide further insight into the complex associations of pain sensitivity that can be used in future research.

Acute analgesic effects of nicotine and tobacco in humans: a meta-analysis

Although animal models have consistently demonstrated acute pain inhibitory effects of nicotine and tobacco, human experimental studies have yielded mixed results. The main goal of this meta-analysis was to quantify the effects of nicotine/tobacco administration on human experimental pain threshold and tolerance ratings. A search of PubMed and PsycINFO online databases identified 13 eligible articles, including k = 21 tests of pain tolerance (N = 393) and k = 15 tests of pain threshold (N = 339). Meta-analytic integration for both threshold and tolerance outcomes revealed that nicotine administered through tobacco smoke and other delivery systems (eg, patch, nasal spray) produced acute analgesic effects that may be characterized as small to medium in magnitude (Hedges g = 0.35, 95% confidence interval = 0.21-0.50). Publication bias-corrected estimates remained significant and indicated that these effects may be closer to small. Sex composition was observed to be a significant moderator, such that pain threshold effects were more robust among samples that included more men than women. These results help to clarify a mixed literature and may ultimately help to inform the treatment of both pain and nicotine dependence. Pain and tobacco smoking are both highly prevalent and comorbid conditions. Current smoking has been associated with more severe chronic pain and physical impairment. Acute nicotine-induced analgesia could make smoking more rewarding and harder to give up. Future research should use dynamic measures of experimental pain reactivity and further explore biopsychosocial mechanisms of action.

Smoking increases risk of pain chronification through shared corticostriatal circuitry

Smoking is associated with increased incidence of chronic pain. However, the evidence is cross-sectional in nature, and underlying mechanisms remain unclear. In a longitudinal observational study, we examined the relationship between smoking, transition to chronic pain, and brain physiology. In 160 subjects with subacute back pain (SBP: back pain lasting 4-12 weeks, and no prior back pain [BP] for at least 1 year) pain characteristics, smoking status, and brain functional properties were measured repeatedly over 1 year. Sixty-eight completed the study, subdivided into recovering (SBPr, n = 31) and persisting (SBPp, n = 37), based on >20% decrease in BP over the year. Thirty-two chronic back pain (CBP: duration > 5 years) and 35 healthy controls were similarly monitored. Smoking prevalence was higher in SBP and CBP but not related to intensity of BP. In SBP, smoking status at baseline was predictive of persistence of BP 1 year from symptom onset (differentiating SBPp and SBPr with 0.62 accuracy). Smoking status combined with affective properties of pain and medication use improved prediction accuracy (0.82). Mediation analysis indicated the prediction of BP persistence by smoking was largely due to synchrony of fMRI activity between two brain areas (nucleus accumbens and medial prefrontal cortex, NAc-mPFC). In SBP or CBP who ceased smoking strength of NAc-mPFC decreased from precessation to postcessation of smoking. We conclude that smoking increases risk of transitioning to CBP, an effect mediated by corticostriatal circuitry involved in addictive behavior and motivated learning.

The influence of physical activity on pain thresholds in patients with depression and multiple somatoform symptoms

OBJECTIVES

Pain is a common symptom with high occurrence in somatoform syndromes and depressive disorders. Research in this area often focuses on experimental induction of pain and subsequent assessment of pain thresholds, ensuring repeatable stimuli of defined quality. Results on sensitivity to experimental pain in major depression are inconclusive, and data on pain thresholds in multiple somatoform symptoms are scarce. The goals of the present study were to differentiate between groups regarding the pressure pain thresholds, and to investigate the possible influence of physical activity on the pain thresholds in these groups. We postulate that physical fitness and physical activity influence pain thresholds in depression and persons with multiple somatoform symptoms.

METHODS

Thirty-eight persons with major depression, 26 persons with a minimum of 6 to 8 somatoform symptoms (somatoform symptom index 8, SSI-8), and 47 healthy participants participated in the study. Baseline values of pressure pain thresholds assessed at different sites of the body were compared with those after 1 week of increased and 1 week of reduced physical activity.

RESULTS

We used repeated measurement design (MANCOVA) and partial correlations for data analysis. Depressed participants reported lower pain thresholds compared with controls, and persons with SSI-8 showed intermediate thresholds. After 1 week of physical activity, participants reported higher pain thresholds. Men had higher pain thresholds following activity as compared with women. Participants who reported higher general fitness also showed higher pain thresholds. Sensitivity to pressure pain is associated with depression, but not with multiple somatoform symptoms.

DISCUSSION

Short low-graded exercise can have reducing effects on perception of pressure pain. Physical activity level is a relevant covariate when using pressure pain assessment. Reduced general fitness can partially account for lower pain thresholds in depression.

Alcohol and tobacco use and heart rate reactivity to a psychosocial stressor in an adolescent population

BACKGROUND

Few studies have investigated physiological stress (re)activity in relation to substance use, especially in adolescents. Using substances is one way to stimulate physiological arousal, therefore inherent hypo-arousal may be associated with substance use in adolescents. The purpose of this study was to examine the relation of autonomic nervous system (ANS) activity with alcohol and tobacco use in adolescents.

METHODS

ANS activity and perceived stress during a social stress procedure were examined in relation to substance use. 275 Dutch adolescents from a general population study provided complete data. Heart rate was recorded continuously during a pre-task rest period, a stressful task period and a post-task recovery period. Alcohol and tobacco use were self-reported.

RESULTS

Adolescents who consumed a medium and high number of alcoholic drinks per week (more than two) exhibited lower heart rates during the entire stress procedure as compared to those who consumed a low number of alcoholic drinks. Adolescents who smoked every day portrayed blunted heart rate reactivity to stress as compared to adolescents who smoked less frequently or not at all. Perceived stress was not related to alcohol or tobacco use.

CONCLUSIONS

Overall lower heart rate in adolescents who drank more and blunted heart rate reactivity to stress in those who used tobacco every day may indicate inherent hypo-arousal of the ANS system in those vulnerable to use substances more often. These adolescents may actively seek out substances in order to achieve a more normalized state of arousal.

Pain, nicotine, and smoking: research findings and mechanistic considerations

Tobacco addiction and chronic pain represent 2 highly prevalent and comorbid conditions that engender substantial burdens upon individuals and systems. Interrelations between pain and smoking have been of clinical and empirical interest for decades, and research in this area has increased dramatically over the past 5 years. We conceptualize the interaction of pain and smoking as a prototypical example of the biopsychosocial model. Accordingly, we extrapolated from behavioral, cognitive, affective, biomedical, and social perspectives to propose causal mechanisms that may contribute to the observed comorbidity between these 2 conditions. The extant literature was 1st dichotomized into investigations of either effects of smoking on pain or effects of pain on smoking. We then integrated these findings to present a reciprocal model of pain and smoking that is hypothesized to interact in the manner of a positive feedback loop, resulting in greater pain and increased smoking. Finally, we proposed directions for future research and discussed clinical implications for smokers with comorbid pain disorders. We observed modest evidence that smoking may be a risk factor in the multifactorial etiology of some chronically painful conditions and that pain may come to serve as a potent motivator of smoking. We also found that whereas animal studies yielded consistent support for direct pain-inhibitory effects of nicotine and tobacco, results from human studies were much less consistent. Future research in the emerging area of pain and smoking has the potential to inform theoretical and clinical applications with respect to tobacco smoking, chronic pain, and their comorbid presentation. (PsycINFO Database Record (c) 2011 APA, all rights reserved).

A randomised double-blind crossover trial of the potential analgesic effect of a transdermal nicotine patch in non-smokers based on objective and subjective assessment

OBJECTIVE

The results of studies of the analgesic effect of nicotine in humans are complex because these studies have included smokers with variable smoking histories. We investigated whether the use of a 17.5 mg transdermal nicotine (TDN) patch decreased the magnitude of pressure pain on the hands of healthy non-smoking volunteers.

DESIGN

This was a randomised double-blind crossover trial. A TDN patch or placebo (drug-free bandage) was applied randomly on the anterior chest of non-smoking volunteers 1 h before the experiments. We measured minimum perceived current and pain threshold on the right hand and then evaluated the magnitude of pressure pain by using the Pain Vision PS-2100 (Nipro Co., Osaka, Japan) which helps in objective quantitative assessment of pain magnitude. After estimating minimum perceived current, pressure pain was produced using a combination of 100-g discs and a rod. The rod and the discs weighing 0 (no disc), 200 (two discs), 400 (four discs), 200 (two discs) and 0 g (no disc) were placed consecutively in this order on the right hand and pain threshold was measured. At the same time, volunteers were asked to rate pain on a numerical rating scale (NRS). Minimum perceived current is the current at which the volunteer perceives the first sensation on applying gradually increasing pulsed current. Pain threshold is the compatible electrode current at which the volunteer feels the intensity of pressure pain. Pain degree is calculated as (pain threshold-minimum perceived current)/minimum perceived current × 100.

PARTICIPANTS

Forty non-smoking volunteers were enrolled in this study.

RESULTS

No significant differences between groups were observed in minimum perceived current, pain threshold, pain degree or NRS. Of the volunteers who received the nicotine patch, four became anorexic and nauseated and two required anti-emetics.

CONCLUSION

The nicotine patch had no analgesic effect in non-smoking volunteers.

Enhanced pain perception prior to smoking cessation is associated with early relapse

Accumulated evidence suggests that nicotine induces analgesia, and endogenous pain regulatory mechanisms may be altered by chronic smoking. The extent to which individual differences in pain perception are related to smokers' ability to abstain from smoking has not been directly examined. Seventy-one smokers who were interested in quitting completed a pre-cessation laboratory session which included the cold pressor test (CPT). Pain ratings were collected during and after CPT. Also, mood changes, cardiovascular measures, and salivary cortisol samples were evaluated prior to, during, and after CPT. Participants attended 4 weekly follow-up assessment sessions after their quit day. Cox regression analysis revealed that higher pain ratings during and after CPT predicted greater risk for smoking relapse. These results remained significant after affective and physiological responses to CPT were controlled, suggesting that pain ratings prior to smoking cessation are potentially useful in identifying smokers who are at greater risk of early smoking relapse and may reflect underlying putative risk for nicotine dependence and relapse.

The effects of depression and smoking on pain severity and opioid use in patients with chronic pain

Depression and smoking are common comorbid conditions among adults with chronic pain. The aim of this study was to determine the independent effects of depression on clinical pain and opioid use among patients with chronic pain according to smoking status. A retrospective design was used to assess baseline levels of depression, clinical pain, opioid dose (calculated as morphine equivalents), and smoking status in a consecutive series of patients admitted to a 3-week outpatient pain treatment program from September 2003 through February 2007. Depression was assessed using the Centers for Epidemiologic Studies-Depression scale, and clinical pain was assessed using the pain severity subscale of the Multidimensional Pain Inventory. The study cohort (n=1241) included 313 current smokers, 294 former smokers, and 634 never smokers. Baseline depression (P=.001) and clinical pain (P=.001) were greater among current smokers compared to former and never smokers, and the daily morphine equivalent dose was greater among smokers compared to never smokers (P=.005). In multivariate linear regression analyses, baseline pain severity was independently associated with greater levels of depression, but not with smoking status. However, status as a current smoker was independently associated with greater opioid use (by 27mg/d), independent of depression scores. The relationship between depression, smoking status, opioid use, and chronic pain is complex, and both depression and smoking status may be potentially important considerations in the treatment of patients with chronic pain who utilize opioids. This study found that pain severity was associated with greater depression but not smoking; however, smoking was associated with greater opioid use, independent of depression.

Beta2* nicotinic acetylcholine receptors modulate pain sensitivity in acutely abstinent tobacco smokers

INTRODUCTION

Nicotine and tobacco smoking administration have demonstrated antinociceptive effects that are mediated by the nicotinic acetylcholine receptor containing the beta2* subunit (beta(2)*-nAChR). In this study, we examined the relationship between beta(2)*-nAChR availability and nociception during acute withdrawal in human tobacco smokers using [(123)I]5-IA-85380 ([(123)I]5-IA) and single photon emission computed tomography (SPECT) brain imaging.

METHODS

Tobacco smokers (n = 24, aged 34 +/- 11 years) participated in the cold pressor task during acute withdrawal (up to 3 hr) and a second cold pressor task following 7-13 days of smoking abstinence on the day they were imaged with [(123)I]5-IA SPECT. The cold pressor task is used to measure pain sensitivity (when subjects first feel pain) and pain tolerance (when subjects cannot withstand pain).

RESULTS

Following 7-13 days of tobacco smoking abstinence, increased pain sensitivity, for example, shorter time to first feel pain, was significantly associated with higher beta(2)*-nAChR availability in the thalamus (r = -.43), parietal (r = -.50), frontal (r = -.55), anterior cingulate (r = -.44), temporal (r = -.43), and occipital (r = -.48) cortices. The percent change in pain sensitivity from the first to second cold pressor task was significantly correlated with beta(2)*-nAChR availability in the thalamus (r = -.57), cerebellum (r = -.50), striatum (r = -.057), parietal (r = -.46), anterior cingulate (r = -.48), temporal (r = -.55), and occipital (r = -.57) cortices. Similar associations were not observed with pain tolerance.

DISCUSSION

This suggests that beta(2)*-nAChRs play a role in pain sensitivity but not pain tolerance during tobacco smoking withdrawal. If individuals are more likely to relapse in response to painful stimuli, lower beta(2)*-nAChR availability during acute abstinence may be protective.

Haemodynamic reactions to acute psychological stress and smoking status in a large community sample

Exaggerated haemodynamic reactions to acute psychological stress have been implicated in a number of adverse health outcomes. This study examined, in a large community sample, the cross-sectional associations between haemodynamic reactivity and self-reported smoking status. Blood pressure and heart rate were measured at rest and in response to a 3-minute arithmetic stress task. Participants were classified as current, ex-, or non-smokers by their response to a simple prompt. Smokers had significantly smaller SBP and DBP reactions to acute stress than ex- and non-smokers; current and ex-smokers had lower HR reactivity. These effects remained significant following adjustment for a host of variables likely to be associated with reactivity and/or smoking. Although the act of smoking acutely increases haemodynamic activity, the present findings contribute to a growing body of literature showing that smokers have blunted reactivity to mental stress. They also support the hypothesis that blunted reactivity may be characteristic of a range of dependencies. The present results also suggest that smoking status needs to be considered in the design and analysis of stress reactivity studies.

Tobacco/nicotine and endogenous brain opioids

Smoking is a major public health problem with devastating health consequences. Although many cigarette smokers are able to quit, equal numbers of others cannot! Standard medications to assist in smoking cessation, such as nicotine replacement therapies and bupropion, are ineffective in many remaining smokers. Recent developments in the neurobiology of nicotine dependence have identified several neurotransmitter systems that may contribute to the process of smoking maintenance and relapse. These include: especially dopamine, but also norepinephrine, 5-hydroxytryptamine, acetylcholine, endogenous opioids, gamma-aminobutyric acid (GABA), glutamate, and endocannabinoids. The present review examines the limited contribution of the endogenous opioid system to the complex effects of nicotine/tobacco smoking.

Self-reported hard physical work combined with heavy smoking or overweight may result in so-called Modic changes

Background

Recently, the MRI finding of "Modic changes" has been identified as pathologic spinal condition that probably reflects a vertebral inflammatory process (VIP), which coincides with spinal pain in most. We hypothesized that heavy smoking in combination with macro- or repeated microtrauma could lead to VIP. The objectives were to investigate if combinations of self-reported heavy smoking, hard physical work, and overweight would be more strongly linked with VIP than with other spinal conditions, such as degenerated discs and non-specific low back pain (LBP).

Methods

Secondary analysis was made of a data base pertaining to a population-based cross-sectional study. A population-generated cohort of 412 40-yr old Danes provided questionnaire information on smoking, weight, height, type of work, and LBP. MRI was used to determine the presence/absence of disc degeneration and of VIP. Associations were tested between three explanatory variables (type of work, smoking, and body mass index) and four outcome variables (LBP in the past year, more persistent LBP in the past year, disc degeneration, and VIP). Associations with these four outcome variables were studied for each single explanatory variable and for combinations of two at a time, and, finally, in a multivariable analysis including all three explanatory variables.

Results

There were no significant associations between the single explanatory variables and the two pain variables or with disc degeneration. However, VIP was found in 15% of non-smokers vs. 26% of heavy smokers. Similarly, VIP was noted in 11% of those in sedentary jobs vs. 31% of those with hard physical work. Further, the prevalence of VIP in those, who neither smoked heavily nor had a hard physical job was 13%, 25% in those who either smoked heavily or had a hard physical job, and 41% in those who both smoked heavily and worked hard. The odds ratio was 4.9 (1.6–13.0) for those who were both heavy smokers and had a hard physical job as compared to those who were classified as "neither". Similar but weaker findings were noted for the combination of overweight and hard physical work but not for the combination of smoking and overweight.

Conclusion

Hard physical work in combination with either heavy smoking or overweight is strongly associated with VIP. If this finding can be reproduced in other studies, it may have consequences in relation to both primary and secondary prevention of LBP, because blue collar workers, who are most likely to experience the consequences of LBP, also are those who are most likely to smoke.

Test-retest reliability of pressure pain threshold measurements of the upper limb and torso in young healthy women

The goal of this study was to determine the intra- and interday reliability of pressure pain thresholds (PPT) in the upper extremity and torso of asymptomatic women. Nineteen healthy women (20-39 years) with no underlying musculoskeletal problems had 3 PPT trials performed on 8 different locations in the upper extremity and torso over 4 consecutive days. The test-retest reliability of PPT values was robust and highly consistent over the 4 days. The PPT intraclass correlations (ICC) were highly consistent and repeatable over the 4 days of testing (day 1: ICC = 0.94; day 2: ICC = 0.96; day 3: ICC = 0.97 and day 4: ICC = 0.96). When compared with baseline measurements obtained on day 1, the PPT values were significantly lower (P < .05) on days 2, 3, and 4 at all 8 locations. Although the PPT test-retest reliability is robust and consistent throughout the 4 days, there appears to be a similar overall decline in the magnitude of the absolute PPT response at each of the 8 locations. A specific explanation for this greater overall sensitivity in PPTs at all 8 locations is lacking; however, a centrally mediated alteration in pressure/pain sensation could contribute to the overall trend observed in this study.

PERSPECTIVE

PPT measurements of the upper limb and torso will be significantly lower with repeated measures over a short period time. A standardized evaluation grid should be included in baseline so as to accurately evaluate the progression in shoulder rehabilitation in women with shoulder dysfunction.

Tobacco control for anesthesiologists

Anesthesiologists daily witness the consequences of tobacco use, the most common preventable cause of death. Smoking-related diseases such as atherosclerosis and chronic obstructive pulmonary disease increase anesthetic risk, and even smokers without overt disease are at increased risk for morbidity such as pulmonary and wound-related complications. Evidence suggests that stopping smoking will reduce the frequency of these complications. Nicotine and the other constituents of cigarette smoke, such as carbon monoxide, have important physiologic effects that may affect perioperative management. In addition, it is now apparent that the scheduling of elective surgery represents an excellent opportunity for smokers to quit in the long term. This review serves as an introduction to tobacco control for anesthesiologists, first examining issues of importance to perioperative management. It then discusses how anesthesiologists and other perioperative physicians can help address tobacco use, both at an individual level with their patients, and by contributing to the implementation of effective public health strategies in their countries. Anesthesiologists can play a key role in helping their patients quit smoking. Effective tobacco control measures applied to surgical patients will not only improve immediate perioperative outcomes but also long-term health.

Antinociception induced by chronic exposure of rats to cigarette smoke

To investigate if chronic exposure to cigarette smoke induces analgesia, rats were exposed to concentrated cigarette smoke in an environmental chamber over four successive 5-day blocks (6 h/day), with 2 smoke-free days between blocks. A control group was exposed to room air. Tail flick latencies increased significantly (analgesia) during each smoke exposure block, with a relative decline in analgesia across blocks (tolerance) and a return to control levels during the first three smoke-free interludes while remaining higher after the conclusion of the 4-week exposure period. Mechanical (von Frey) withdrawal thresholds declined over time in smoke-exposed and control groups, with the smoke-exposed group showing significantly lower thresholds. Plasma nicotine reached 95.4 +/- 32 (S.D.) ng/ml at the end of weekly smoke exposure and declined to 44.9 +/- 10.6 ng/ml 24 h after withdrawal. Rats lost weight during smoke exposure and quickly regained weight during smoke-free interludes and at the cessation of smoke exposure. Analgesia may contribute to the initiation of smoking, and rapid reversal of the analgesic effect following acute exposure may contribute to the difficulty in quitting smoking.

Smoking and smokeless tobacco: increased risk for oral pain

Tobacco has been linked with several pain conditions that include musculoskeletal pain, rheumatoid arthritis, and fibromyalgia. This study documented associations between smoking and smokeless tobacco use and measures of orofacial pain and oral pain impacts (activity reduction and trouble with sleep) assessed during a 48-month time period. These data were collected as part of the Florida Dental Care Study, a longitudinal study of oral health among 873 adults aged 45 years and older at baseline. Twenty-five percent of the study participants were current users of some form of tobacco, and 34% were former users. Separate models were tested for smoking and smokeless tobacco. Current tobacco users were at increased risk of experiencing a range of painful oral symptoms. We also found that behavioral impacts associated with oral pain are sensitive to differences in tobacco use status. Our data also support the supposition that once tobacco cessation occurs, the risk for pain associated with oral disease decreases significantly. No differences were found between former users and those never having used tobacco across any of the pain measures. Strengths of the current study include the longitudinal methodology, assessment of different pain symptoms with potentially differing etiology, and that several markers of tobacco use were used (prevalence, consumption, and duration).

PERSPECTIVE

This study considers the harmful effects of tobacco use on oral health. Smokers were at significantly increased risk for oral pain and related limitation of daily activities. The data also suggest that the risk for oral pain associated with tobacco use decreases significantly if tobacco cessation occurs.

Cannabis, tobacco, and caffeine use modify the blood pressure reactivity protection of ascorbic acid

Cannabis, caffeine, and tobacco use are associated with increased mesolimbic dopamine activity. Ascorbic acid (AA) modulates some dopaminergic agent effects, and was recently found to decrease systolic blood pressure (SBP) stress reactivity. To examine how AA SBP stress reactivity protection varies by use of these substances, data from an AA trial (Cetebe, 3000 mg/day for 14 days; N=108) were compared by substance use level regarding SBP reactivity to the anticipation and actual experience phases of a standardized psychological stressor (10 min of public speaking and arithmetic). Self-reported never users of cannabis, persons not currently smoking tobacco, and persons consuming three or more caffeine beverages daily all exhibited AA SBP stress reactivity protection to the actual stressor, but not during the anticipation phase. Conversely, self-reported ever cannabis users, current tobacco smokers, and persons consuming less than three caffeine beverages daily exhibited the AA SBP protection during the anticipation phase, but only the lower caffeine consumption group exhibited AA protection during both phases. Covariates (neuroticism, extraversion, and depression scores, age, sex, body mass index) were all nonsignificant. Results are discussed in terms of dopaminergic effects of these substances, modulation of catecholaminergic and endothelial activity, and AA support of coping styles.

Intraocular pressure changes: the influence of psychological stress and the Valsalva maneuver

The effects of psychological stress and the Valsalva maneuver on short-term variations of intraocular pressure (IOP) were studied in 49 healthy adults. Psychological stress consisted of mental arithmetic tasks presented in counterbalanced order by computer and by the experimenter. Additionally, a standardized Valsalva maneuver was performed (in counterbalanced order with the psychological stressors). IOP was measured with a Goldmann tonometer before and after performance of each stressor. All three stressors transiently and highly significantly increased IOP, although the Valsalva maneuver produced changes of a greater magnitude (10.2 mmHg) than the psychological stressors (1.3 mmHg). Subjective stress ratings and heart rate increased in response to all stressors. There were no effects of task sequence, eye muscle tension, sex, smoking status (some smokers misreported their smoking status), or regular marijuana use, but regular physical exercise was associated with less IOP increase during psychological stress.

Antinociceptive effects of the novel neuronal nicotinic acetylcholine receptor agonist, ABT-594, in mice

ABT-594 [5-((2R)-azetidinylmethoxy)-2-chloropyridine], a novel neuronal nicotinic acetylcholine receptor agonist, produced significant antinociceptive effects in mice against both acute noxious thermal stimulation--the hot-plate and cold-plate tests--and persistent visceral irritation--the abdominal constriction (writhing) assay (maximally-effective dose in each test 0.62 micromol/kg, i.p.). This effect was not stereoselective since the S-enantiomer, A-98593 [5-((2S)-azetidinylmethoxy)-2-chloropyridine], produced similar antinociceptive effects in this dose range. The effect in the hot-plate test peaked at 30 min after i.p. administration and was still present 60 min, but not 120 min, after injection. ABT-594 was orally active, but 10-fold less potent by this route than after i.p. administration. The antinociceptive effect of ABT-594 was prevented, but not reversed, by the noncompetitive neuronal nicotinic acetylcholine receptor antagonist mecamylamine (5 micromol/kg, i.p.). In contrast, the antinociceptive effect of ABT-594 was not prevented by hexamethonium (10 micromol/kg, i.p.), a neuronal nicotinic acetylcholine receptor antagonist that does not readily enter the central nervous system, nor by naltrexone (0.8 micromol/kg), an opioid receptor antagonist. Thus, initiation of antinociception by ABT-594 involves activation of central nicotinic acetylcholine receptors, but does not require activation of naltrexone-sensitive opioid receptors. The antinociceptive effects of morphine and ABT-594 in the mouse hot-plate test appeared to be additive, but ABT-594 did not potentiate the respiratory depression produced by morphine when the two compounds were coadministered. ABT-594 reduced body temperature and spontaneous exploration in the antinociceptive dose range, but did not reliably impair motor coordination in the rotarod test. Thus, it is unlikely that the antinociceptive effects result simply from impaired motor function. The compound also produced an anxiolytic-like effect in the elevated plus maze (at 0.019 and 0.062 micromol/kg, i.p.). Preliminary safety testing revealed an ED50 for overt seizure production of 1.9 micromol/kg, i.p. and an LD50 of 19.1 micromol/kg i.p. in mice, values 10 and 100 times the minimum effective antinociceptive dose of the compound. ABT-594 increased the duration of ethanol-induced hypnotic effects, tended to increase pentobarbital-induced hypnotic effects (P = 0.0502), and had no effect on pentobarbital-induced lethality. These data indicate that ABT-594 is a centrally acting neuronal nicotinic acetylcholine receptor agonist with potent antinociceptive and anxiolytic-like effects in mice.

The effects of recent food, alcohol, and tobacco intake and the temporal scheduling of testing on cardiovascular activity at rest and during psychological stress

Participants in cardiovascular psychophysiological studies receive various instructions regarding restraints on alcohol, food, and tobacco intake prior to testing. Further, although the hour of testing is frequently a concern, little attention is paid to month of the year. In the present study, we examined cardiovascular activity at rest and in response to a laboratory stress task in 1,272 men in terms of these variables. Alcohol consumption among alcohol users and food intake within 4 hr of testing were associated with higher baseline diastolic blood pressure (BP) but lower baseline heart rate (HR). Tobacco use in smokers within 1 hr of testing was associated with elevated baseline BP and HR. Hour of testing was related to baseline HR, whereas month of the year was associated with baseline BP. In contrast to these baseline effects, cardiovascular reactions to the laboratory stress task were largely immune to these contextual influences.

Smoking produces a smaller increase in heart rate in the natural smoking environment than in the laboratory

We tested whether the physiological effects of smoking a cigarette under standard conditions in a laboratory are similar to those seen in a room at home. On two separate test days ten healthy smokers were prepared with a small physiological recorder and were then requested to carry out a protocol requiring them to smoke one of their cigarettes in their usual way either (1) in the laboratory where they had never smoked previously, or (2) at home, alone in a quiet room where they regularly smoke. The experiment which counterbalanced the order of testing showed that in both test situations smoking produced a clear increase in heart rate (HR) and in skin conductance (SC); however, when testing was carried out in the home environment the increase in the HR was significantly less than in the laboratory. No significant differences were found for the baseline HR values in the two environments and there were no significant situational effects in the SC data. It was concluded that under conditions of normal smoking, data on the physiological effects of a cigarette in the laboratory may not be fully generalizable to those seen in the natural smoking situation. Several possible mechanisms of this situationally-specific effect of smoking were discussed.