Occurrence of Taenia species in pigs in slaughterhouses in Phu Tho province, northern Vietnam.

Pigs act as the intermediate hosts of the zoonotic tapeworms Taenia solium and Taenia asiatica, as well as of the non-zoonotic Taenia hydatigena. In Vietnam, human taeniasis and cysticercosis have been reported throughout the country; however, data on porcine cysticercosis are scarce. Our study aimed to estimate the prevalence of Taenia spp. in slaughtered pigs in two districts in Phu Tho, a mountainous province in northern Vietnam from where neurocysticercosis patients commonly originate. The carcasses of 399 pigs from 51 small-scale abattoirs were checked for cysticerci, while tongue, liver, masseter muscles, diaphragm and heart were sliced and examined. Retrieved cysticerci underwent polymerase chain reaction-restriction fragment length polymorphism and sequencing for species confirmation. Blood was also collected to detect antibodies by lentil lectin-purified glycoprotein enzyme-linked immunoelectrotransfer blot (LLGP-EITB) and recombinant T24H antigen (rT24H)-EITB and circulating antigens by B158/B60 Ag-ELISA. In two pigs, T. asiatica cysticerci were found, confirming the presence of the parasite in pigs in Vietnam at a low prevalence (0.5%; 95% exact confidence interval (CI): 0-1.19%). Cysticerci of T. solium were found in none of the pigs, although one serum sample was positive for antibodies in both LLGP-EITB and rT24H-EITB. Furthermore, a high prevalence of T. hydatigena cysticercosis was observed (18.0%; 95% Wilson score CI: 14.6-22.1%). In more than half of the T. hydatigena-positive pigs, circulating antigens were detected by Ag-ELISA, confirming that this test cannot be used to diagnose T. solium cysticercosis in this region. Finally, Spirometra erinaceieuropaei was found in one pig liver. It is the first record of this zoonotic cestode species in pigs in Vietnam. Overall, the findings confirmed the complex epidemiology of Taenia spp. in pigs in Vietnam.

Long-term outcome in survivors of neonatal tetanus following specialist intensive care in Vietnam.

BACKGROUND: Neonatal tetanus continues to occur in many resource-limited settings but there are few data regarding long-term neurological outcome from the disease, especially in settings with critical care facilities. METHODS: We assessed long-term outcome following neonatal tetanus in infants treated in a pediatric intensive care unit in southern Vietnam. Neurological and neurodevelopmental testing was performed in 17 survivors of neonatal tetanus and 18 control children from the same communities using tools previously validated in Vietnamese children. RESULTS: The median age of children assessed was 36 months. Eight neonatal tetanus survivors and 9 community control cases aged < 42 months were tested using the Bayley III Scales of Infant and Toddler Development (Bayley III-VN) and 8 neonatal tetanus survivors and 9 community controls aged ≥42 months were tested using the Movement Assessment Battery for Children. No significant reductions in growth indices or neurodevelopmental scores were shown in survivors of neonatal tetanus compared to controls although there was a trend towards lower scores in neonatal tetanus survivors. Neurological examination was normal in all children except for two neonatal tetanus survivors with perceptive deafness and one child with mild gross motor abnormality. Neonatal tetanus survivors who had expienced severe disease (Ablett grade ≥ 3) had lower total Bayley III-VN scores than those with mild disease (15 (IQR 14-18) vs 24 (IQR 19-27), p = 0.05) with a significantly lower cognitive domain score (3 (IQR 2-6) severe disease vs 7 (IQR 7-8) mild disease, p = 0.02). CONCLUSIONS: Neonatal tetanus is associated with long-term sequelae in those with severe disease. In view of these findings, prevention of neonatal tetanus should remain a priority.

Diagnostic value of cerebral vasospasm by transcranial doppler ultrasound in Vietnamese patients with subarachnoid hemorrhage.

OBJECTIVE: Although the application of transcranial Doppler (TCD) ultrasonography in clinical diagnosis of cerebral vasospasm is popular in clinical practice in Vietnam, available evidence of the predictive value of vasospasm on TCD in the literature was mostly reported from large institutions in developed countries. Hence, this study was conducted to evaluate the value of TCD ultrasonography in the diagnosis of vasospasm in patients with subarachnoid hemorrhage (SAH) in Vietnam. PATIENTS AND METHODS: This is a prospective observational study of all aneurysmal SAH patients consecutively admitted to a single center between 2008 and December 2011. TCD and 64-slice computed tomographic angiography (CTA) were used to cerebral vasospasm in SAH patients. RESULTS: 316 patients were analyzed (mean age = 52.97±12.27 years, 52.2% males). There were statistically significant difference rates of the cerebral vasospasm by Hunt and Hess Classification and Fisher classification (p <0.01). The proportion of the patients with cerebral vasospasm who were diagnosed exactly by TCD was 95.2%, while the proportion of the patients without cerebral vasospasm diagnosed exactly was 91.5%. TCD predictive diagnostic value was the highest, with the sensitivity of 0.95 (95% CI: 0.91-0.98), specificity of 0.91 (95% CI: 0.85-0.96), positive predictive value of 0.94 (5% CI: 0.90-0.97) and negative predictive value of 0.93 (95 CI: 0.87-0.97). Hemiplegia was the clinical symptom with the highest diagnostic value with the sensitivity of 0.34 (95% CI: 0.27-0.41), specificity of 0.92 (95% CI: 0.86-0.96), positive predictive value of 0.86 (95% CI: 0.76-0.93) and negative predictive value of 0.49 (95% CI: 0.41-0.54). CONCLUSIONS: Evidence of vasospasm diagnosis on TCD ultrasonography was found with high accuracy. Current study enables to suggest the wide application of TCD in Vietnam health facilities from central to grassroots levels instead of the CTA use.

Chalcone synthase and its functions in plant resistance.

Chalcone synthase (CHS, EC 2.3.1.74) is a key enzyme of the flavonoid/isoflavonoid biosynthesis pathway. Besides being part of the plant developmental program the CHS gene expression is induced in plants under stress conditions such as UV light, bacterial or fungal infection. CHS expression causes accumulation of flavonoid and isoflavonoid phytoalexins and is involved in the salicylic acid defense pathway. This review will discuss CHS and its function in plant resistance.

Real-time Subject-specific Head and Facial Mimic Animation System using a Contactless Kinect Sensor and System of Systems Approach.

Facial palsies due to stroke, accidental and sportive injuries or sometimes without etiology, affect the professional and personal lives of involved patients. These disorders are not only a functional handicap but also a social integration impairment. The recovery of facial mimics with a normal and symmetrical facial expression allows involved patients to improve their living conditions and social identity. Current approaches lack of visual feedbacks. To monitor facial mimics and head movements in a quantitative and objective manners, a computer-aided animation system needs to be developed. Numerous systems have been proposed using single camera, stereo camera, 3-D scanner, and Kinect approaches. In particular, Kinect contactless sensor has been proven to be very suitable for 3-D facial simulation applications. However, little studies have employed the Kinect sensor for real-time head animation applications. Consequently, this study developed a real-time head and facial mimic animation system using the contactless Kinect sensor and the system of systems approach. To evaluate the accuracy of the subject-specific Kinect-based geometrical models, magnetic resonance imaging (MRI) data were used. As results, the mean distance deviation between generated Kinect-based and reconstructed MRI-based geometrical head models are approximately 1 mm for two tested subjects. The generation times are 9.7 s ± 0.3 and 0.046 s ± 0.005 by using the full facial landmarks and MPEG-4 facial landmarks respectively. Real-time head and facial mimic animations were illustrated. Particularly, the system could be executed at a very high framerate (60 fps). Further developments relate to the integration of texture information and internal structures such as a skull and muscle network to develop a full subject specific head and facial mimic animation system for facial mimic rehabilitation.

Method transfer for fast liquid chromatography in pharmaceutical analysis: application to short columns packed with small particle. Part II: gradient experiments.

Liquid chromatography (LC) is currently considered as the gold standard in pharmaceutical analysis. Today, there is an increasing need for fast and ultra-fast methods with good efficiency and resolution for achieving separations in a few minutes or even seconds. A previous article (i.e. method transfer for fast LC in pharmaceutical analysis. Part I: isocratic separation) described a simple methodology for performing a successful method transfer from conventional LC to fast and ultra-fast LC in isocratic mode. However, for performing complex separations, the gradient mode is often preferred. Thus, this article reports transfer rules for chromatographic separations in gradient mode. The methodology was applied for the impurity profiling of pharmaceutical compounds, following two strategies. A first approach, using short columns (20-50mm) packed with 3.5microm particles and optimized HPLC instrumentation (with reduced extra-column and dwell volumes), was applied for the separation of a pharmaceutical drug and eight related impurities. Special attention was paid to the dwell (gradient delay) volume, which causes the most detrimental effect for transferring a gradient method. Therefore, the dwell volume was simultaneously decreased with the column dead volume. Under optimal conditions, it was possible to reduce the analysis time by a factor of 10, with an acceptable loss in resolution since the column length reduction is less critical in gradient than isocratic mode. The second tested approach was Ultra Performance Liquid Chromatography (UPLC), where sub-2microm particles were used simultaneously with very high pressures (up to 1000bar). A complex pharmaceutical mixture containing 12 compounds was separated in only 1.5min allowing a reduction of the analysis time by a factor of 15 in comparison to a conventional method, with similar peak capacity.

Validation of an ultra-fast UPLC-UV method for the separation of antituberculosis tablets.

A simple method using ultra performance LC (UPLC) coupled with UV detection was developed and validated for the determination of antituberculosis drugs in combined dosage form, i. e. isoniazid (ISN), pyrazinamide (PYR) and rifampicin (RIF). Drugs were separated on a short column (2.1 mm x 50 mm) packed with 1.7 mum particles, using an elution gradient procedure. At 30 degrees C, less than 2 min was necessary for the complete separation of the three antituberculosis drugs, while the original USP method was performed in 15 min. Further improvements were obtained with the combination of UPLC and high temperature (up to 90 degrees C), namely HT-UPLC, which allows the application of higher mobile phase flow rates. Therefore, the separation of ISN, PYR and RIF was performed in less than 1 min. After validation (selectivity, trueness, precision and accuracy), both methods (UPLC and HT-UPLC) have proven suitable for the routine quality control analysis of antituberculosis drugs in combined dosage form. Additionally, a large number of samples per day can be analysed due to the short analysis times.

Recent developments in liquid chromatography--impact on qualitative and quantitative performance.

In order to reduce the analysis time and maintain good efficiency in liquid chromatography (LC), several solutions are currently being investigated. The focus of this study was to compare, both qualitatively and quantitatively, the chromatographic performance of a conventional LC with selected approaches, namely monolithic supports, high temperature LC (up to 90 degrees C), and sub-2 microm particles combined with high pressure (up to 1000 bar). This comparison was achieved from a qualitative point of view with a special attention paid to the analysis of time reduction, efficiency improvement, and pressure constraint. For this purpose, the different approaches were discussed using Knox curves and other kinetic plots. It appeared that columns packed with sub-2 microm particles under high-pressure conditions (UPLC) were well adapted and this option represents an attractive alternative to conventional LC; however, the other alternative approaches should not be neglected. The quantitative evaluation of these techniques was performed on the basis of the validation of results of a pharmaceutical formulation (Rapidocaïne), following SFSTP 2003 guidelines. Fast-LC approaches demonstrated equivalent performance to conventional LC in terms of trueness, precision, and accuracy profile, with a significant time reduction (up to 8x) according to the selected methodology.

High throughput liquid chromatography with sub-2 microm particles at high pressure and high temperature.

In this study, ultra performance liquid chromatography (UPLC) using pressures up to 1,000 bar and columns packed with sub-2 microm particles has been combined with high temperature mobile phase conditions (up to 90 degrees C). By using high temperature ultra performance liquid chromatography (HT-UPLC), it is possible to drastically decrease the analysis time without loss in efficiency. The stability and chromatographic behavior of sub-2 microm particles were evaluated at high temperature and high pressure. The chromatographic support remained stable after 500 injections (equivalent to 7,500 column volumes) and plate height curves demonstrated the capability of HT-UPLC to obtain fast separations. For example, a separation of nine doping agents was performed in less than 1 min with sub-2 microm particles at 90 degrees C. Furthermore, a shorter column (30 mm length) was used and allowed a separation of eight pharmaceutical compounds in only 40s.

Method transfer for fast liquid chromatography in pharmaceutical analysis: application to short columns packed with small particle. Part I: isocratic separation.

Liquid chromatography (LC) is considered to be the gold standard in pharmaceutical analysis. Today, there is a need for fast and ultra-fast methods with good efficiency and resolution for achieving separations in few minutes or even seconds. The present work describes a simple methodology for performing a successful method transfer from conventional LC to fast and ultra-fast LC. In order to carry out fast separations, short columns (20-50mm) packed with small particles (3.5 and 1.7 microm) were used and their chromatographic performance was compared to that of a conventional column (150 mm, 5 microm). For that purpose, an optimized LC system was employed to limit extra-column volumes which can have a dramatic impact on efficiency and resolution. This paper reports the fundamental equations used for transferring an isocratic chromatographic separation performed with a given column geometry and chemistry to a smaller column packed with similar or identical stationary phase, without influence on chromatographic performance. For this purpose, the flow rate and the injected volume need to be adapted. The effect of column length and particle size reduction on chromatographic resolution and analysis time was described for an isocratic separation. Using the method transfer equations, it is possible to predict the new conditions to be used, for fast and ultra-fast separations. In this work, ultra-fast separations were achieved thanks to a new generation of instrumentation (ultra performance liquid chromatography, UPLC) which uses simultaneously short column packed with sub-2 microm particles and ultra-high pressure (up to 1000 bar). This work demonstrates an analysis time reduction up to a factor 12, compared to a conventional LC separation, without affecting the quality of separation. Therefore, the complete resolution of a pharmaceutical formulation was achieved in only a few seconds.

Association between in-hospital guideline adherence and postdischarge major adverse outcomes of patients with acute coronary syndrome in Vietnam: a prospective cohort study.

OBJECTIVE: We aimed to determine the association between physician adherence to prescribing guideline-recommended medications during hospitalisation and 6-month major adverse outcomes of patients with acute coronary syndrome in Vietnam. DESIGN: Prospective cohort study. SETTING: The study was carried out in two public hospitals in Vietnam between January and October 2015. Patients were followed for 6 months after discharge. PARTICIPANTS: Patients who survived during hospitalisation with a discharge diagnosis of acute coronary syndrome and who were eligible for receiving at least one of the four guideline-recommended medications. EXPOSURES: Guideline adherence was defined as prescribing all guideline-recommended medications at both hospital admission and discharge for eligible patients. Medications were antiplatelet agents, beta-blockers, ACE inhibitors or angiotensin II receptor blockers and statins. MAIN OUTCOME MEASURE: Six-month major adverse outcomes were defined as all-cause mortality or hospital readmission due to cardiovascular causes occurring during 6 months after discharge. Cox regression models were used to estimate the association between guideline adherence and 6-month major adverse outcomes. RESULTS: Overall, 512 patients were included. Of those, there were 242 patients (47.3%) in the guideline adherence group and 270 patients (52.3%) in the non-adherence group. The rate of 6-month major adverse outcomes was 30.5%. A 29% reduction in major adverse outcomes at 6 months after discharge was found for patients of the guideline adherence group compared with the non-adherence group (adjusted HR, 0.71; 95% CI, 0.51 to 0.98; p=0.039). Covariates significantly associated with the major adverse outcomes were percutaneous coronary intervention, prior heart failure and renal insufficiency. CONCLUSIONS: In-hospital guideline adherence was associated with a significant decrease in major adverse outcomes up to 6 months after discharge. It supports the need for improving adherence to guidelines in hospital practice in low-income and middle-income countries like Vietnam.

Chromatographic behaviour and comparison of column packed with sub-2 microm stationary phases in liquid chromatography.

In order to reduce the analysis time and maintain good efficiency in liquid chromatography, it is advisable to simultaneously decrease the column length and the particle size of the chromatographic support. Therefore, several manufacturers have developed and commercialized short columns filled with particles that have a diameter smaller than 2 microm. The focus of this work was to check the chromatographic performance of such columns and compare possibilities offered by sub-2 microm supports with conventional columns in terms of analysis time reduction and efficiency improvements. For this purpose, different parameters were discussed namely: separation impedance (E), Knox curves (h,v), and number of plates by time unit (N/t0). Kinetic plots were also drawn. It appeared that sub-2 microm supports were well adapted to improve chromatographic performance and to reduce the analysis time. Furthermore, it was also demonstrated that the best chromatographic performances were reached with high pressure systems (up to 1000 bar).

Expression of altered alpha2-adrenergic phenotypic traits in normotensive humans at genetic risk of hereditary (essential) hypertension.

BACKGROUND: Essential (hereditary) hypertension is a common, though complex, trait with substantial heritability, but a still-obscure mode of inheritance. In this disorder with relatively late onset, knowledge of phenotypes with earlier penetrance would aid genetic analyses, as well as assessment of risk. OBJECTIVE: Because alpha2-adrenergic receptor alterations are among the most heritable in experimental genetic hypertension, we hypothesized enhanced expression of alpha2-adrenergic phenotypic traits in still-normotensive humans at genetic risk of hypertension. METHODS: We evaluated hemodynamic (blood pressure, cardiac output, systemic vascular resistance, stroke volume, and cardiac contractility) and biochemical (plasma drug, catecholamine, renin, and chromogranin A levels) responses to alpha2-adrenergic blockade with intravenous yohimbine in 84 normotensive subjects stratified by genetic risk of essential hypertension (67 with positive family histories and 17 with negative family histories of hypertension), as well as 18 subjects with established essential hypertension. Results were evaluated by analysis of variance, normal likelihood ratio test, and by maximum likelihood analysis for bimodality (i.e. mixtures) of response distributions. RESULTS: Blood pressure rose (P<0.001) during alpha2-adrenergic blockade, with greater response (P<0.001) in members of the hypertensive than in members of the normotensive group. Hemodynamically, the rise in blood pressure resulted from an increase in cardiac output (P<0.001), with associated increases in stroke volume (P=0.002) and cardiac contractility (P=0.006), without an overall change in systemic vascular resistance. Biochemically, plasma norepinephrine (P<0.001), epinephrine (P=0.001), and chromogranin A (P=0.02) rose, suggesting augmentation of efferent exocytotic sympathoadrenal activity. Cardiac output and stroke volume responses were correlated to increments in plasma catecholamines (especially epinephrine) for the positive group, but not for the negative group. Baseline plasma catecholamines predicted increments of stroke volume after administration of yohimbine (P=0.003-0.007) for the positive but not for the negative group. Simultaneous comparison of means and variances of cardiac output and stroke volume alpha2-adrenergic responses, by using a normal likelihood ratio test, revealed highly significant (P=0.025 to P<0.0001) differences between the groups of subjects with and without family histories of hypertension. Frequency histogram suggested that there was a bimodal distribution of responses of stroke volume to alpha2-adrenergic blockade for the normotensive group with positive family histories of hypertension; maximum likelihood analysis strongly rejected the hypothesis of a unimodal distribution, whereas the hypothesis of bimodality could not be rejected (chi2=18.4, P=0.0004). The second (exaggerated) mode of response of stroke volume to alpha2-adrenergic blockade, defined by maximum likelihood analysis, was found for 9.5% of subjects in the normotensive group with positive family histories of hypertension, and was characterized by significantly different responses of cardiac output (P=0.001), stroke volume (P<0.001), contractility (P<0.001), heart rate (P=0.03), systemic vascular resistance (P<0.001), and epinephrine (P<0.001). Even prior to alpha2-adrenergic blockade, baseline stroke volume (P=0.01), heart rate (P=0.04), systemic vascular resistance (P=0.005), and catecholamine (P=0.001-0.005) values for this subgroup were different than control values. CONCLUSIONS: We conclude that heterogeneous, bimodally distributed hemodynamic responses to alpha2-adrenergic blockade in subjects with positive family histories of hypertension suggest a discrete subgroup with early expression of perhaps Mendelian traits associated with risk of later development of hypertension. Such phenotypic traits ('intermediate phenotypes'), with earlier penetrance than hypertension itself, can be

Pain responses to experimental chewing in myofascial pain patients.

Although patients with myofascial pain of the masticatory muscles often report that chewing exacerbates their pain, this has never been verified experimentally. In this study, pain was assessed before and after chewing in 20 asymptomatic subjects and in 61 patients with muscle pain. First, self-reports of pain were obtained with a checklist and on five-point category scales (CAT) at the screening visit. None of the asymptomatic subjects reported that mastication or other jaw movements caused pain. On the other hand, the majority of patients reported that movements were painful (67.2%, checklist; 78.7%, CAT). Afterward, pain intensity at rest and after chewing on wax for 3 min was reported on 100-mm Visual Analogue Scales (VAS). No asymptomatic subjects had pain before or after the chewing test, while about 50% of the patients reported an increase of pain after chewing. In this subgroup, mean pain intensity increased by 102.6%. However, mean pain intensity after chewing decreased by 56.6% in about 30% of the patient sample. These patients had significantly higher resting pain than the first subgroup. These data show that a short chewing test can exacerbate pain in most myofascial pain patients but has no effect in asymptomatic subjects. Surprisingly, the exercise decreased pain in an important subgroup of patients. These results suggest that two subgroups of myofascial pain patients may exist with opposite reactions to exercise. It remains to be seen if these reactions are due to two different pathologies or to the fact that the pre-exercise pain levels were significantly different in the two groups.

Power and sample size calculations for clinical trials of myofascial pain of jaw muscles.

When a clinical trial is planned, the approximate number of subjects needed for significant differences between/among groups to be detected must be estimated. Sample-size calculations provide the investigator with this information. This paper discusses the choice of outcome measures and describes the steps used to estimate the numbers of subjects necessary for a study that compares treatments for patients with chronic myofascial pain of jaw muscles. Within- and between-subject variances were estimated for the chosen variables, the subjects' pain ratings on visual analogue scales. Sample sizes were then calculated for theoretical differences between groups by pre-treatment means and overall standard deviations (Cohen, 1977). The results of this analysis can be used by other researchers when planning studies involving these types of patients.

Renal kallikrein excretion: role of ethnicity, gender, environment, and genetic risk of hypertension.

BACKGROUND AND OBJECTIVE: Alterations in renal kallikrein excretion are well-described in hypertension, and kallikrein excretion may predict risk of developing hypertension, but kallikrein excretion has not been directly compared across several ethnic strata, nor have the effects of ethnicity, gender, environment, and genetic risk of hypertension been simultaneously considered as determinants of kallikrein. METHODS: We investigated determinants of kallikrein excretion in a cross-section of n = 204 normotensive subjects stratified by ethnicity (119 Caucasian, 33 African-American, 52 Asian), gender (109 men, 95 women), environment (spontaneous electrolyte intake/excretion), and heredity (genetic risk (family history) of hypertension). Results were interpreted by analysis of variance (with Bonferroni post hoc comparison corrections), analysis of covariance, multiple linear regression, and maximum likelihood. RESULTS: Urinary kallikrein activity varied substantially (F = 5.30, P = 0.006) across the three ethnic groups, with African-American values approximately 50% lower than Caucasian (P = 0.005) or Asian (P = 0.02). Ethnicity and gender (T = 3.24, P = 0.001) had independent effects on kallikrein, with women excreting approximately 50% more kallikrein than men, regardless of ethnicity. Subjects at genetic risk of hypertension were over-represented (P = 0.048) in the lower stratum of a bimodal distribution of kallikrein excretion (chi-square = 29.6, P < 0.001). Potassium excretion was diminished in African-Americans (P < 0.001 to P = 0.002), and in a multivariate analysis, potassium excretion was the strongest correlate of kallikrein excretion (T = 4.10, P = 0.0001). In a subset of Caucasian and African-American individuals, African-Americans exhibited diminished excretion of not only kallikrein and potassium, but also aldosterone (P = 0.003), suggesting a mechanistic link between potassium and kallikrein excretion in their ethnic variations. CONCLUSIONS: Kallikrein excretion is influenced by several independent determinants, both hereditary (gender, ethnicity, and genetic risk of hypertension) and environmental (potassium intake and excretion). Ethnicity and environment may interact uniquely to influence kallikrein, as demonstrated by the case of African-Americans with diminutions of both kallikrein and potassium excretion. These results suggest a mechanism whereby kallikrein excretion is diminished in African-Americans, as well as therapeutic strategies to correct this deficiency. Finally, the identified determinants of kallikrein excretion will require analytic adjustment during genetic studies of this 'intermediate phenotype' in hypertension. Journal of Human Hypertension (2000) 14, 461-468

Gender differences in pain.

A review of the literature on gender and clinical pain reveals a disproportionate representation of women receiving treatment for many pain conditions and suggests that women report more severe pain, more frequent pain, and pain of longer duration than do men. Gender differences in pain perception have also been extensively studied in the laboratory, and ratings of experimentally induced pain also show some sex disparity, with females generally reporting lower pain thresholds and tolerance than males. However, there is little consensus on whether these apparent differences reflect the way men and women respond to pain, differing social rules for the expression of pain, or biologic differences in the way noxious stimuli are processed. In this paper, our working hypothesis is that the higher prevalence of chronic orofacial pain in women is a result of sex differences in generic pain mechanisms and of as-yet unidentified factors unique to the craniofacial system. We will review the evidence concerning gender differences in the prevalence of pain conditions, with a focus on orofacial pain conditions. Evidence and hypotheses concerning biologic and psychosocial factors that could influence prevalence rates will also be discussed.

Comparison of pain and quality of life in bruxers and patients with myofascial pain of the masticatory muscles.

Although it has been suggested that bruxism is a cause or a risk factor in myofascial pain of the masticatory muscles, the prevalence of pain in bruxers and its characteristics have not been assessed or compared to those of myofascial pain patients in general. In this study, self-reports of pain and quality of life were recorded on 100-mm visual analogue and five-point category scales from two research populations: (1) 19 nocturnal bruxers who participated in a polysomnographic study and (2) 61 patients with myofascial pain of the masticatory muscles with no evidence of bruxism who participated in a controlled clinical trial on the efficacy of oral splints. The data show that pain was more intense in those bruxers who reported pain than among the myofascial pain patients, even though pain was not the chief complaint of bruxers. Both conditions reduced the patient's quality of life, although pain patients (either bruxism or myofascial pain) appeared to be much more affected than bruxers who were pain-free. The fact that pain from bruxism was worst in the morning suggests that it is possibly a form of postexercise muscle soreness. Myofascial pain, which was worst late in the day, is likely to have a different etiology.

Comorbidity between myofascial pain of the masticatory muscles and fibromyalgia.

This study compared myofascial pain of the masticatory muscles to fibromyalgia. Study data show that, in both myofascial pain and fibromyalgia patients, facial pain intensity and its daily pattern and effect on quality of life are very similar. This indicates that fibromyalgia should be included in the differential diagnosis for myofascial pain of the masticatory muscles. However, with the higher prevalence of neurologic and gastrointestinal symptoms, and the stronger words used to describe the affective dimension of pain, it is apparent that fibromyalgia may be a more debilitating condition than myofascial pain of the masticatory muscles. Since the intensity of facial pain was strongly and significantly correlated to the body-pain index in fibromyalgia but not in myofascial pain patients, it can be concluded that facial pain may be part of the clinical manifestations of fibromyalgia, but it is unlikely to be related to body pain in myofascial pain patients. On the other hand, while body pain is episodic in most myofascial pain patients, it is constant and more severe in the majority of fibromyalgia patients. This difference in the pain patterns suggests that body pain in fibromyalgia and myofascial pain could have different etiologies. The lack of correlation between the intensity of pain and the length of time since onset also supports the concept that myofascial pain of the masticatory muscles and fibromyalgia are unlikely to be progressive disorders.