In Vitro Induction of Human Regulatory T Cells Using Conditions of Low Tryptophan Plus Kynurenines.

Thymic regulatory T cells (tTregs) and induced regulatory T cells (iTregs) suppress murine acute graft-versus-host disease (GVHD). Previously, we demonstrated that the plasmacytoid dendritic cell indoleamine 2,3-dioxygenase (IDO) fosters the in vitro development of human iTregs via tryptophan depletion and kynurenine (Kyn) metabolites. We now show that stimulation of naïve CD4+ T cells in low tryptophan (low Trp) plus Kyn supports human iTreg generation. In vitro, low Trp + Kyn iTregs and tTregs potently suppress T effector cell proliferation equivalently but are phenotypically distinct. Compared with tTregs or T effector cells, bioenergetics profiling reveals that low Trp + Kyn iTregs have increased basal glycolysis and oxidative phosphorylation and use glutaminolysis as an energy source. Low Trp + Kyn iTreg viability was reliant on interleukin (IL)-2 in vitro. Although in vivo IL-2 administration increased low Trp + Kyn iTreg persistence on adoptive transfer into immunodeficient mice given peripheral blood mononuclear cells to induce GVHD, IL-2-supported iTregs did not improve recipient survival. We conclude that low Trp + Kyn create suppressive iTregs that have high metabolic needs that will need to be addressed before clinical translation.

Clinical grade manufacturing of human alloantigen-reactive regulatory T cells for use in transplantation.

Regulatory T cell (Treg) therapy has the potential to induce transplantation tolerance so that immunosuppression and associated morbidity can be minimized. Alloantigen-reactive Tregs (arTregs) are more effective at preventing graft rejection than polyclonally expanded Tregs (PolyTregs) in murine models. We have developed a manufacturing process to expand human arTregs in short-term cultures using good manufacturing practice-compliant reagents. This process uses CD40L-activated allogeneic B cells to selectively expand arTregs followed by polyclonal restimulation to increase yield. Tregs expanded 100- to 1600-fold were highly alloantigen reactive and expressed the phenotype of stable Tregs. The alloantigen-expanded Tregs had a diverse TCR repertoire. They were more potent than PolyTregs in vitro and more effective at controlling allograft injuries in vivo in a humanized mouse model.

Experimental pain sensitivity differs as a function of clinical pain severity in symptomatic knee osteoarthritis.

OBJECTIVE: Pain in knee osteoarthritis (OA) has historically been attributed to peripheral pathophysiology; however, the poor correspondence between objective measures of disease severity and clinical symptoms suggests that non-local factors, such as altered central processing of painful stimuli, also contribute to clinical pain in knee OA. Consistent with this notion, recent evidence demonstrates that patients with knee OA exhibit increased sensitivity to painful stimuli at body sites unaffected by clinical pain. DESIGN: In order to further investigate the contribution of altered pain processing to knee OA pain, the current study tested the hypothesis that symptomatic knee OA is associated with enhanced sensitivity to experimental pain stimuli at the knee and at remote body sites unaffected by clinical pain. We further anticipated that pain sensitivity would differ as a function of the OA symptom severity. Older adults with and without symptomatic knee OA completed a series of experimental pain assessments. A median split of the Western Ontario and McMaster Universities Index of Osteoarthritis (WOMAC) was used to stratify participants into low vs high OA symptom severity. RESULTS: Compared to controls and the low symptom group, individuals in the high symptom group were more sensitive to suprathreshold heat stimuli, blunt pressure, punctuate mechanical, and cold stimuli. Individuals in the low symptomatic OA group subgroup exhibited experimental pain responses similar to the pain-free group on most measures. No group differences in endogenous pain inhibition emerged. CONCLUSIONS: These findings suggest that altered central processing of pain is particularly characteristic of individuals with moderate to severe symptomatic knee OA.

Vitamin D, race, and experimental pain sensitivity in older adults with knee osteoarthritis.

OBJECTIVE: Low circulating serum levels of 25-hydroxyvitamin D (referred to hereafter as vitamin D) have been correlated with many health conditions, including chronic pain. Recent clinical practice guidelines define vitamin D levels <20 ng/ml as deficient and levels of 21-29 ng/ml as insufficient. Vitamin D insufficiency, including the most severe levels of deficiency, is more prevalent in black Americans. Ethnic and race group differences have been reported in both clinical and experimental pain, with black Americans reporting increased pain. The purpose of this study was to examine whether variations in vitamin D levels contribute to race differences in knee osteoarthritis pain. METHODS: The sample consisted of 94 participants (74% women), including 45 blacks and 49 whites with symptomatic knee osteoarthritis. Their average age was 55.8 years (range 45-71 years). Participants completed a questionnaire on knee osteoarthritis symptoms and underwent quantitative sensory testing, including measures of sensitivity to heat-induced and mechanically induced pain. RESULTS: Blacks had significantly lower levels of vitamin D compared to whites, demonstrated greater clinical pain, and showed greater sensitivity to heat-induced and mechanically induced pain. Low levels of vitamin D predicted increased experimental pain sensitivity, but did not predict self-reported clinical pain. Group differences in vitamin D levels significantly predicted group differences in heat pain and pressure pain thresholds at the index knee and ipsilateral forearm. CONCLUSION: These data demonstrate that race differences in experimental pain are mediated by differences in the vitamin D level. Vitamin D deficiency may be a risk factor for increased knee osteoarthritis pain in black Americans.

Generation and large-scale expansion of human inducible regulatory T cells that suppress graft-versus-host disease.

Adoptive transfer of thymus-derived natural regulatory T cells (nTregs) effectively suppresses disease in murine models of autoimmunity and graft-versus-host disease (GVHD). TGFß induces Foxp3 expression and suppressive function in stimulated murine CD4+25- T cells, and these induced Treg (iTregs), like nTreg, suppress auto- and allo-reactivity in vivo. However, while TGFß induces Foxp3 expression in stimulated human T cells, the expanded cells lack suppressor cell function. Here we show that Rapamycin (Rapa) enhances TGFß-dependent Foxp3 expression and induces a potent suppressor function in naive (CD4+ 25-45RA+) T cells. Rapa/TGFß iTregs are anergic, express CD25 at levels higher than expanded nTregs and few cells secrete IL-2, IFNγ or IL-17 even after PMA and Ionomycin stimulation in vitro. Unlike other published methods of inducing Treg function, Rapa/TGFß induces suppressive function even in the presence of memory CD4+ T cells. A single apheresis unit of blood yields an average ~240 × 109 (range ~ 70-560 × 109) iTregs from CD4+25- T cells in ≤ 2 weeks of culture. Most importantly, Rapa/TGFß iTregs suppress disease in a xenogeneic model of GVHD. This study opens the door for iTreg cellular therapy for human diseases.

Methods used by Dental Practice-based Research Network (DPBRN) dentists to diagnose dental caries.

OBJECTIVES: To (1) identify the methods that dentists in The Dental Practice-Based Research Network (DPBRN) use to diagnose dental caries; (2) quantify their frequency of use and (3) test the hypothesis that certain dentist and dental practice characteristics are significantly associated with their use. METHODS: A questionnaire about methods used for caries diagnosis was sent to DPBRN dentists who reported doing some restorative dentistry; 522 dentists participated. Questions included the use of dental radiographs, the dental explorer, laser fluorescence, air-drying and fiber-optic devices and magnification as used when diagnosing primary, secondary/recurrent or non-specific caries lesions. Variations on the frequency of their use were tested using multivariate analysis and Bonferroni tests. RESULTS: Overall, the dental explorer was the instrument most commonly used to detect primary occlusal caries and caries at the margins of existing restorations. In contrast, laser fluorescence was rarely used to help diagnose occlusal primary caries. For proximal caries, radiographs were used to help diagnose 75%­100% of lesions by 96% of the DPBRN dentists. Dentists who use radiographs most often to assess proximal surfaces of posterior teeth were significantly more likely to also report providing a higher percentage of patients with individualized caries prevention (p=.040) and seeing a higher percentage of pediatric patients (p=.001). CONCLUSION: The use of specific diagnostic methods varied substantially. The dental explorer and radiographs are still the most commonly used diagnostic methods..

Interferon (IFN) beta acts downstream of IFN-gamma-induced class II transactivator messenger RNA accumulation to block major histocompatibility complex class II gene expression and requires the 48-kD DNA-binding protein, ISGF3-gamma.

Interferon (IFN) gamma, a cardinal proinflammatory cytokine, induces expression of the gene products of the class II locus of the major histocompatibility complex (MHC), whereas IFN-alpha or -beta suppresses MHC class II expression. The mechanism of IFN-beta-mediated MHC class II inhibition has been unclear. Recently, a novel factor termed class II transactivator (CIITA) has been identified as essential for IFN-gamma-induced MHC class II transcription. We studied the status of IFN-gamma-induced CIITA messenger RNA (mRNA) accumulation and CIITA-driven transactivation in IFN-beta-treated cells and used cell lines that had defined defects in the type I IFN response pathway to address the roles of IFN signaling components in the inhibition of MHC class II induction. IFN-beta treatment did not suppress IFN-gamma-induced accumulation of CIITA mRNA. After cells were stably transfected with CIITA, endogenous MHC class II genes were constitutively expressed, and MHC class II promoters, delivered by transfection, were actively transcribed in CIITA-expressing cells. Expression of these promoters was significantly impaired by pretreatment with IFN-beta. These results suggest that IFN-beta acts downstream of CIITA mRNA accumulation, and acts in part by reducing the functional competence of CIITA for transactivating MHC class II promoters. IFN stimulated gene factor 3 (ISGF3) gamma was essential for IFN-beta to mediate inhibition of MHC class II induction, regardless of whether MHC class II transcription was stimulated by IFN-gamma or directly by CIITA expression. Results of these experiments suggest that inhibition of MHC class II in IFN-beta-treated cells requires expression of gene(s) directed by the ISGF3-IFN-stimulated response element pathway, and that these gene product(s) may act by blocking CIITA-driven transcription of MHC class II promoters.

Modulation of susceptibility to HIV-1 infection by the cytotoxic T lymphocyte antigen 4 costimulatory molecule.

CD4 T cells activated in vitro by anti-CD3/28-coated beads are resistant to infection by CC chemokine receptor 5 (CCR5)-dependent HIV-1 isolates. In vivo, antigen-presenting cells (APCs) activate CD4 T cells in part by signaling through the T cell receptor and CD28, yet cells stimulated in this manner are susceptible to HIV-1 infection. We show that cytotoxic T lymphocyte antigen 4 (CTLA-4) engagement counteracts the CD28 antiviral effects, and that the ratio of CTLA-4 to CD28 engagement determines the susceptibility of HIV-1 infection. Furthermore, unopposed CTLA-4 signaling provided by CD28 blockade promotes vigorous HIV-1 replication, despite minimal T cell proliferation. Finally, CTLA-4 antibodies decrease the susceptibility of antigen-activated CD4 T cells to HIV, suggesting a potential approach to prevent or limit viral spread in HIV-1-infected individuals.

CD40 ligand (CD154) triggers a short-term CD4(+) T cell activation response that results in secretion of immunomodulatory cytokines and apoptosis.

Signals generated through CD28-B7 and CD40 ligand (CD40L)-CD40 interactions have been shown to be crucial for the induction of long-term allograft survivability. We have recently demonstrated that humanized anti-CD40L (hu5C8) prevents rejection of mismatched renal allografts in primates. To investigate potential mechanisms of CD40L-induced allograft acceptance, we coimmobilized hu5C8 with suboptimal amounts of anti-CD3 to stimulate CD4(+) T cells. We now report that anti-CD3/CD40L costimulation results in CD28-independent activation and subsequent deletion of resting T cells. Coligation of CD3 and CD40L increased expression of CD69, CD25, and CD54 on CD4(+) T cells. We also found that costimulation with anti-CD3/CD40L resulted in enhanced production of interleukin (IL)-10, interferon gamma, and tumor necrosis factor alpha but not IL-2 or IL-6. Interestingly, after several days, anti-CD3/CD40L-mediated activation was followed by apoptosis in a significant population of cells. Consistent with that observation, anti-CD3/CD40L did not enhance the antiapoptotic proteins Bcl-2 and Bcl-xL. Further, the addition of CD28 at 24 h failed to rescue those cells induced to die after costimulation with anti-CD3/CD40L. Together, these data suggest that the graft-sparing effect of hu5C8 in vivo may result in part from early and direct effects on CD4(+) T cells, including a vigorous induction of immunomodulatory cytokines and/or apoptosis of allograft-specific T cells.

Productive infection of neonatal CD8+ T lymphocytes by HIV-1.

CD8+ T lymphocytes confer significant but ultimately insufficient protection against HIV infection. Here we report that activated neonatal CD8+ T cells can be productively infected in vitro by macrophage-tropic (M-tropic) HIV-1 isolates, which are responsible for disease transmission, whereas they are resistant to T cell-tropic (T-tropic) HIV strains. Physiological activation of CD8-alpha/beta+ CD4- T cell receptor-alpha/beta+ neonatal T cells, including activation by allogeneic dendritic cells, induces the accumulation of CD4 messenger RNA and the expression of CD4 Ag on the cell surface. The large majority of anti-CD3/B7.1-activated cord blood CD8+ T cells coexpress CD4, the primary HIV receptor, as well as CCR5 and CXCR4, the coreceptors used by M- and T-tropic HIV-1 strains, respectively, to enter target cells. These findings are relevant to the rapid progression of neonatal HIV infection. Infection of primary HIV-specific CD8+ T cells may compromise their survival and thus significantly contribute to the failure of the immune system to control the infection. Furthermore, these results indicate a previously unsuspected level of plasticity in the neonatal immune system in the regulation of CD4 expression by costimulation.

Use of caries-preventive agents in children: findings from the dental practice-based research network.

PURPOSE: Scientific evidence supports the application of caries-preventive agents in children and adolescents, and this knowledge must be applied to the practice of dentistry. There are few multi-region data that allow for comparisons of practice patterns between types of dental practices and geographical regions. The objective of the present study was to characterise the use of specific caries-preventive agents for paediatric patients in a large multi-region sample of practising clinicians. METHODS: The present study surveyed clinicians from the Dental Practice-based Research Network who perform restorative dentistry in their practices. The survey consisted of a questionnaire that presented a range of questions about caries risk assessment and the use of preventive techniques in children aged 6 to 18 years. RESULTS: Dental sealants (69%) or in-office fluoride (82%) were the most commonly used caries-preventive agents of the caries preventive regimens. The recommendation of at-home caries-preventive agents ranged from 36% to 7%,with the most commonly used agent being non-prescription fluoride rinse. Clinicians who practised in a large group practice model and clinicians who come from the Scandinavian region use caries risk assessment more frequently compared to clinicians who come from regions that had, predominantly, clinicians in private practice. Whether or not clinicians used caries risk assessment with their paediatric patients was poorly correlated with the likelihood of actually using caries-preventive treatments on patients. CONCLUSIONS: Although clinicians reported the use of some form of in-office caries-preventive agent, there was considerable variability across practices. These differences could represent a lack of consensus across practising clinicians about the benefits of caries-preventive agents, or a function of differing financial incentives, or patient pools with differing levels of overall caries risk.

Antiviral effect and ex vivo CD4+ T cell proliferation in HIV-positive patients as a result of CD28 costimulation.

Because stimulation of CD4+ lymphocytes leads to activation of human immunodeficiency virus-type 1 (HIV-1) replication, viral spread, and cell death, adoptive CD4+ T cell therapy has not been possible. When antigen and CD28 receptors on cultured T cells were stimulated by monoclonal antibodies (mAbs) to CD3 and CD28 that had been immobilized, there was an increase in the number of polyclonal CD4+ T cells from HIV-infected donors. Activated cells predominantly secreted cytokines associated with T helper cell type 1 function. The HIV-1 viral load declined in the absence of antiretroviral agents. Moreover, CD28 stimulation of CD4+ T cells from uninfected donors rendered these cells highly resistant to HIV-1 infection. Immobilization of CD28 mAb was crucial to the development of HIV resistance, as cells stimulated with soluble CD28 mAb were highly susceptible to HIV infection. The CD28-mediated antiviral effect occurred early in the viral life cycle, before HIV-1 DNA integration. These data may facilitate immune reconstitution and gene therapy approaches in persons with HIV infection.

Differential regulation of HIV-1 fusion cofactor expression by CD28 costimulation of CD4+ T cells.

Activation of CD4(+) T lymphocytes from human immunodeficiency virus-type 1 (HIV-1)-infected donors with immobilized antibodies to CD3 and CD28 induces a virus-resistant state. This effect is specific for macrophage-tropic HIV-1. Transcripts encoding CXCR4/Fusin, the fusion cofactor used by T cell line-tropic isolates, were abundant in CD3/CD28-stimulated cells, but transcripts encoding CCR5, the fusion cofactor used by macrophage-tropic viruses, were not detectable. Thus, CD3/CD28 costimulation induces an HIV-1-resistant phenotype similar to that seen in some highly exposed and HIV-uninfected individuals.

Caries Diagnosis in Dental Practices: Results From Dentists in a Brazilian Community.

The aim of this study was to assess practices related to diagnosis of dental caries among dentists (n=217) from Araraquara, São Paulo State, Brazil. Data on sociodemographic information and practitioner characteristics were collected using a pretested questionnaire, and data on practices related to caries diagnosis were gathered by using a translated and culturally adapted questionnaire from the US National Dental Practice-Based Research Network. Descriptive statistics and regression analyses were used for data analysis. Respondents reported using in most of their patients radiographs (Rx) to diagnose proximal caries (59%), explorer (Ex) for the diagnosis of occlusal caries (64%) and on the margins of existing restorations (79%), as well as air jet (AJ) with drying (92%). Magnification (M) (25%), fiber optic transillumination (FOTI; 14%), and laser fluorescence (LF) (3%) were used in the minority of patients. Regression analysis revealed that the following dentists' characteristics were significantly associated (p<0.05) with the use of diagnostic methods on a greater percentage of their patients: advanced degree (Rx, FOTI), higher percentage of patients with individualized caries prevention (Rx, FOTI, M), more years since dental school graduation (Ex, M), and work in an exclusively private practice model (LF). In conclusion, most Brazilian dentists from Araraquara reported they most commonly use visual, tactile, and radiographic imaging for the diagnosis of dental caries. Some dentists' characteristics, such as time from dental school graduation and having a postgraduation course, were associated with the use of certain diagnostic methods.

Native reptiles alter their foraging in the presence of the olfactory cues of invasive mammalian predators.

Invasive mammalian predators are linked to terrestrial vertebrate extinctions worldwide. Prey naïveté may explain the large impact invasive predators have on native prey; prey may fail to detect and react appropriately to the cues of novel predators, which results in high levels of depredation. In Australia, the feral cat (Felis catus) and the red fox (Vulpes vulpes) are implicated in more than 30 animal extinctions and the naïveté of native prey is often used to explain this high extinction rate. Reptiles are one group of animals that are heavily preyed upon by F. catus and V. vulpes. However, very few studies have examined whether reptiles are naive to their cues. In this study, we examine the ability of two native reptile species (Morethia boulengeri and Christinus marmoratus) to detect and distinguish between the chemical cues of two invasive predators (V. vulpes and F. catus) and three native predators (spotted-tailed quoll, Dasyurus maculatus; dingo, Canis lupus dingo; eastern brown snake, Pseudonaja textilis), as well as two non-predator controls (eastern grey kangaroo, Macropus giganteus and water). We conducted experiments to quantify the effects of predator scents on lizard foraging (the amount of food eaten) during 1 h trials within Y-maze arenas. We found both study species reduced the amount they consumed when exposed to predator scents-both native and invasive-indicating that these species are not naive to invasive predators. An evolved generalized predator-recognition system, rapid evolution or learned behaviour could each explain the lack of naïveté in some native Australian reptiles towards invasive predators.

Molecular genetic analysis of volatile-anesthetic action.

The mechanism(s) and site(s) of action of volatile inhaled anesthetics are unknown in spite of the clinical use of these agents for more than 150 years. In the present study, the model eukaryote Saccharomyces cerevisiae was used to investigate the action of anesthetic agents because of its powerful molecular genetics. It was found that growth of yeast cells is inhibited by the five common volatile anesthetics tested (isoflurane, halothane, enflurane, sevoflurane, and methoxyflurane). Growth inhibition by the agents is relatively rapid and reversible. The potency of these compounds as yeast growth inhibitors directly correlates with their lipophilicity as is predicted by the Meyer-Overton relationship, which directly correlates anesthetic potency of agents and their lipophilicity. The effects of isoflurane on yeast cells were characterized in the most detail. Yeast cells survive at least 48 h in a concentration of isoflurane that inhibits colony formation. Mutants resistant to the growth-inhibitory effects of isoflurane are readily selected. The gene identified by one of these mutations, zzz4-1, has been cloned and characterized. The predicted ZZZ4 gene product has extensive homology to phospholipase A2-activating protein, a GO effector protein of mice. Both zzz4-1 and a deletion of ZZZ4 confer resistance to all five of the agents tested, suggesting that signal transduction may be involved in the response of these cells to volatile anesthetics.

Judgment of the Quality of Restorative Care as Predictors of Restoration Retreatment: Findings from the National Dental PBRN.

The primary aim of this study was to test the hypothesis that a patient's subjective assessments of the dentist's technical competence, quality of care, and anticipated restoration longevity during a restorative visit are predictive of restoration outcome. This prospective cohort study involved 3,326 patients who received treatment for a defective restoration in a permanent tooth, participated in a baseline patient satisfaction survey, and returned for follow-up. Of the 4,400 restorations that were examined by 150 dentists, 266 (6%) received additional treatment after baseline. Reporting satisfaction with the technical skill of the dentist or quality of the dental work at baseline was not associated with retreatment after baseline. However, patients' views at baseline that the fee was reasonable (odds ratio [OR], 1.6) was associated with retreatment after baseline, whereas satisfaction at baseline with how long the filling would last (OR, 0.6) was associated with less retreatment. These findings suggest that retreatment occurs more often for patients who at baseline are satisfied with the cost or who at baseline have less confidence in the restoration. The authors found no associations between restoration retreatment and the patients' baseline evaluations of the technical skills of their dentists or perceptions of quality care. KNOWLEDGE TRANSFER STATEMENT: Dental patients' ratings of their dentist's skills were not related to a restoration needing retreatment. Patients focus on other aspects of the dental visit when making this judgment.

Orofacial pain symptom prevalence: selective sex differences in the elderly?

This study investigated sex differences in orofacial pain symptoms in a sample of elderly adults. Furthermore, differences across sex were tested on symptom continuity, overall duration, pain severity, activity reduction, and health care utilization, related to each specific symptom. Telephone interviews were conducted with a stratified random sample of community dwelling older (65+) north Floridians. A total of 5860 households were contacted and screened, with 75.3% participating to the point where their eligibility for the study could be determined. Of the remaining households, 1636 completed the interview. Of the total sample, 17.4% reported experiencing at least one of the four target orofacial pain symptoms (jaw joint pain, face pain, oral sores, burning mouth) during the past year, suggesting that orofacial pain symptoms are common in older adults. Our findings for prevalence of each specific symptom (jaw joint pain, 7.7%; face pain, 6.9%; oral sores, 6.4%; toothache, 12.0%; burning mouth, 1.7%) are similar to those estimated by the 1989 National Health Interview Survey, for the US adult population. Consistent with other epidemiological and clinical studies, we found that females were more likely to report jaw joint pain and face pain than males. In contrast to clinical studies, no differences were found on subjective ratings of pain severity, for any symptom. Differences across sex were most likely to be reported for jaw joint pain related variables, suggesting undetermined sex-uniqueness for these symptoms. In contrast to previous studies, older females tended to report lower levels of health care utilization than older males. This is the first study to our knowledge that reports orofacial symptom-specific sex differences among the elderly.

Health care utilization by older adults in response to painful orofacial symptoms.

The purpose of this study was to determine which specific attributes of painful orofacial symptoms serve as predictors of health care utilization in a population based sample of elderly subjects. Furthermore, we documented patterns of health care utilization selection by type of health care provider. To our knowledge, these specific utilization patterns have never before been reported in the pain literature. Telephone interviews were conducted with a stratified random sample of 1636 community dwelling older (65+) north Floridians. A total of 5860 households were contacted and screened, with 75.3% participating to the point where their eligibility for the study could be determined. The percentage of subjects reporting health care utilization for a specific symptom ranged from 62 to 32%. One or more health care visits were reported by at least 50% of those reporting symptoms of toothache pain, facial pain, jaw joint pain and burning mouth in the past 12 months. These rates suggest that elderly individuals are willing and able to seek health care for painful orofacial symptoms. We found that pain intensity was the best predictor of whether an elderly individual utilized health care or not, which suggests that some pain intensity threshold may exist at which health care seeking behavior is initiated. The overall number of visits was not predicted by pain intensity but by other qualities more associated with time or level of dysfunction caused by the symptom. We also found that elderly adults, typically seek care for toothache from a dentist and from physicians for painful orofacial symptoms not associated with the teeth or mouth. These decisions regarding the selection of a health care professional may, in part, be a function of financial and insurance considerations, anatomical site and perception of the role of dentistry in orofacial care.

Sex differences in the perception of noxious experimental stimuli: a meta-analysis.

Fillingim and Maixner (Fillingim, R.B. and Maixner, W., Pain Forum, 4(4) (1995) 209-221) recently reviewed the body of literature examining possible sex differences in responses to experimentally induced noxious stimulation. Using a 'box score' methodology, they concluded the literature supports sex differences in response to noxious stimuli, with females displaying greater sensitivity. However, Berkley (Berkley, K.J., Pain Forum, 4(4) (1995) 225-227) suggested the failure of a number of studies to reach statistical significance suggests the effect may be small and of little practical significance. This study used meta-analytic methodology to provide quantitative evidence to address the question of the magnitude of these sex differences in response to experimentally induced pain. We found the effect size to range from large to moderate, depending on whether threshold or tolerance were measured and which method of stimulus administration was used. The values for pressure pain and electrical stimulation, for both threshold and tolerance measures, were the largest. For studies employing a threshold measure, the effect for thermal pain was smaller and more variable. The failures to reject the null hypothesis in a number of these studies appear to have been a function of lack of power from an insufficient number of subjects. Given the estimated effect size of 0.55 threshold or 0.57 for tolerance, 41 subjects per group are necessary to provide adequate power (0.70) to test for this difference. Of the 34 studies reviewed by Fillingim and Maixner, only seven were conducted with groups of this magnitude. The results of this study compels to caution authors to obtain adequate sample sizes and hope that this meta-analytic review can aid in the determination of sample size for future studies.