Discharge patterns of human C-fibers induced by itching and burning stimuli

1. The aim of this investigation was to study the peripheral neural mechanisms of the C-fiber-mediated modalities of burning pain and itch by the use of microneurography of human unmyelinated afferents. 2. Sixteen stable recordings of single C-fibers and 6 multiunit recordings were obtained from the superficial radial nerves of volunteers. All units were excited by stimulating their receptive fields with von Frey bristles (range 10-600 mN), and all but four units were also driven by radiant heat stimulation. 3. Histamine was iontophoretically applied to the receptive fields of these units for 20 or 30 s and was found to provoke itching sensations lasting several minutes, together with wheal and flare responses. Subsequently a solution containing 20 or 30% mustard oil was applied to the receptive field of the respective unit, which provoked a sensation of burning pain. 4. One-half of the units were excited by histamine, and the median discharge rates derived from interspike intervals ranged from approximately 0.1 to 0.8 Hz. Mustard oil-induced activity was observed in all histamine-sensitive units and also in three single units and in one multiunit recording that revealed no histamine response. Median interval-derived discharge rates ranged from 0.2 to 1.2 Hz. 5. Analysis of the interspike interval distribution and of the autocorrelation function derived from the chemically induced discharges of single units provided no evidence for an encoding of itch and burning pain in different discharge patterns of units responding to histamine and to mustard oil.(ABSTRACT TRUNCATED AT 250 WORDS)     

Sensitization of nociceptive cutaneous nerve fibers from the rat's tail by noxious mechanical stimulation

Summary This single fiber study on rat tail nerve afferents attempts to establish a peripheral neural correlate for the hyperalgesia to mechanical stimulation which follows injury to the skin. Mechano-heat sensitive C fibers (MH-C or polymodal nociceptors) and high-threshold mechanoreceptive A delta fibers (HTM-A delta) were examined with a series of constant noxious pressure stimulations (4-6-8-4 N on 25 mm², 120 s each, 5 min intervals). These injurious stimuli were either directed to the most sensitive spot of the receptive fields (central stimulation) or closely outside their borders (1–5 mm). With this protocol no clear sensitization was seen in MH-C fibers apart from a stronger dynamic response to central stimulation in some of them. In contrast, most HTM-A delta units, irrespective of the site of noxious stimulation, developed spontaneous activity, lowering of their von Frey thresholds and expansion of their receptive fields. All HTM-A delta units responded to outside stimulation: upon the first stimulus (4 N) there was a delayed discharge of continuously increasing frequency (recruited response), but the onset of the last stimulation (4 N repeated) evoked vigorous dynamic responses in many fibers. The recruitment of HTM-A delta nociceptor activity may contribute to post-injury hyperalgesia to mechanical stimulation and it may counteract adaptation of the single afferent fiber during prolonged noxious influence.On leave from the Laboratoire de Physiologie, Faculté de Médecine Lyon-Sud, Chemin du Petit Revoyet, F-69600 Ouillins, France     

Risk of insomnia and hypnotics use among emergency physicians

This study investigated the risk of insomnia and hypnotics use among emergency physicians. This cross-sectional study recruited physicians working in Taiwanese hospitals in 2015 and the general population as the participants. Data from 1,097 emergency physicians obtained from the National Health Insurance Research Database were grouped into the case group, whereas 14,112 nonemergency physicians and 4,388 people from the general population were categorized into the control groups. This study used logistic regression and conditional logistic regression to compare the risks of insomnia between emergency and nonemergency physicians and between emergency physicians and the general population, respectively. The prevalence of insomnia among emergency physicians, nonemergency physicians and general population was 5.56%, 4.08%, and 1.73%, respectively. Compared with nonemergency physicians and the general population, emergency physicians had a significantly higher risk of insomnia. The proportions of emergency physicians, nonemergency physicians, and general population using hypnotics were 19.96%, 18.24%, and 13.26%, respectively. Among emergency physicians who used hypnotics, 49.77%, 25.57%, and 24.66% used only benzodiazepines, only nonbenzodiazepines, and both benzodiazepines and nonbenzodiazepines, respectively. Nonpharmacological interventions to improve insomnia and reminder of safe use of hypnotics to emergency physicians can serve as references for hospitals in developing health-promoting activities.     

Cultural diversity, stress, and depression: working women in the Americas

Social support lengthens life, and stressors induce morbidity early in life and death later. Social supports and stressors, however, particularly those embedded in daily social interactions, exhibit important forms of cultural variation not yet incorporated into stress measurements. This article reports a clinically useful measure of stress applicable to culturally diverse populations. Ninety working women with a wide range of ages, educational attainments, class backgrounds, and historical origins (Africa, northwest Europe, Hispanic, and Native Americans) provided cultural data on the meaning of stress. Consensus analysis, principal components analysis and Cronbach's alpha, and logistic regression document content validity of the stress scale items and the reliability and construct validity of the stress scale. The meaning of social supports (words or acts that imply respect, equality, or help or otherwise lead one to feel special and important) and stressors (words or acts that demean, imply inferiority, impede achievement, or otherwise lead one to feel bad about oneself) experienced in the course of daily social interaction cuts across cultural differences in other realms of life. Informants with a recent history of stress experienced a risk of depressive symptoms 85 times higher than informants without such a history. Standardized cultural research methods yield an instrument based on potential cultural universals that can facilitate clinical assessment and management of stress and health outcomes, such as depression, in culturally diverse populations.     

SALMONELLA BACTERAEMIA OCCURRING CONCURRENTLY WITH THE FIRST PRESENTATION OF SYSTEMIC LUPUS ERYTHEMATOSUS

There is increasing recognition of the association between Salmonellainfections and systemic lupus erythematosus (SLE). However,these infections have usually occurred in patients with establishedSLE who were receiving immunosuppressive therapy. We describetwo young women with previously undiagnosed SLE who developedSalmonella bacteraemia. Neither of these patients had receivedimmunosuppressive drugs. From these and two previously reportedpatients, it may be concluded that SLE per se is likely to beassociated with a defect in host defences to Salmonella bacteria. KEY WORDS: SLE, Non-typhoid Salmonella, Septicaemia     

Left vagus nerve stimulation suppresses experimentally induced pain

OBJECTIVE: To test whether electric stimulation of the vagus nerve has an antinociceptive effect in humans. BACKGROUND: In a variety of animal studies, vagus nerve stimulation was shown to inhibit nociceptive behavior as well as electric responses of spinal nociceptive neurons. In humans, chronic left vagus nerve stimulation is used to treat pharmacologically refractory epilepsy. METHODS: The authors investigated experimental pain in 10 patients with seizures before and twice after implantation of a vagus nerve stimulator by using different controlled stimuli, including noxious heat, tonic pressure, and short impact. Pain was quantified on a visual analogue scale. Twelve nonepileptic age- and gender-matched individuals served as control subjects. RESULTS: Vagus nerve stimulation reduced increasing pain associated with trains of five consecutive stimuli at 1.5-second intervals ("wind-up"; p < 0.001). In a similar manner, pain on tonic pressure was reduced by vagus nerve stimulation (p < 0.03). Pain associated with single-impact stimuli as well as heat pain thresholds were unaltered under vagus nerve stimulation. Thus, vagus nerve stimulation led to pain relief predominantly in experimental procedures in which pain magnitude was amplified by central processing. The antinociceptive effect was independent of the acute on-off cycles of vagus nerve stimulation. CONCLUSIONS: Vagus nerve stimulation is effective in reducing pain in humans. In humans, the antinociceptive effect might rely on central inhibition rather than alterations of peripheral nociceptive mechanisms. These results indicate a promising, potential future role of vagus nerve stimulation in pain treatment.     

Proteus syndrome

Abstract: This female Asian (Malay) baby had clinical features of Proteus syndrome. She had a large right facial lipolymphangioma with hyperpigmentation of the overlying skin. There was a smaller lymphangioma over the left side of her neck with excess nuchal folds, macrodactyly and bilateral talipes equinovarus. Despite the extensive hemifacial swelling, there was no evidence of upper respiratory tract obstruction. Generalized seizures developed on the sixth day of life which were controlled with phenobarbital. The lymphangiomas were excised without recurrence.     

早期清创缝合后不使用抗生素的临床分析

目的研究早期清创缝合后不预防性地使用抗生素对创口的影响。方法我科自2004年1月至2005年6月有选择性地对50例皮肤软组织挫裂伤进行了急诊清创缝合,术后未给予抗生素,并连续观察伤口的变化。结果本组所有伤口均未发生感染。结论早期清创及规范的清创缝合术后可以不必预防性地使用抗生素。     

Caregiver Practices of Families of Children with and Without Physical Disability

Reports suggest children with physical disability are at greater risk than peers for negative caregiver interactions. The environmental, parental, and child characteristics associated with variation in caregiver practices among families of children with (n?=?450) and without physical disability (n?=?450) in a nationally representative sample from the U.S. Agreement and variation about the shared meaning of “caregiver practices” were measured using consensus analysis. Associated parent, child, and family characteristics were identified using regression analysis. Parents did not spank, hit back, yell, ignore, put to work, or make fun of their children as a punishment. Parents maintained rules set about eating, bedtime, chores, and watching television. They reported playing with children, preparing food for them, going to religious services, reading, singing songs, and telling stories with their children. They reported not being involved in organized exercise and art classes. Child’s socio-emotional skills and behaviors (β?=??.331), socio-economic status (β?=??.223), the influence of religion on raising child (β?=??.180), race/ethnicity of the parent (β?=??.071), and physical disability (β?=??.104) explained 24 % of the variance in caregiver practices (F?=?32.34, p?<?.000). More negative caregiver practices are associated with families of children with lower levels of socio-emotional skills and behaviors, lower socio-economic status, less religious influence on child rearing practices, who are not Euro-American, or whose children have physical disability. Children’s socio-emotional skills and behaviors explained the largest amount of variance in caregiver practices, not disability status. Health professionals working with children with physical disability should target developing socio-emotional skills to support positive child-parent interactions and promote positive outcomes.     

Morphology of the Cardiac Conduction System in Patientswith Electrophysiologically Proven Dual Atrioventricular Nodal Pathways

Conduction System in Dual AV Nodal Pathways. Introduction: Although the electrophysiologic criteria for dual atrioventricular nodal pathways are well established, the anatomical substrate is still unclear.
Methods and Results: We examined the hearts from 10 patients who had been studied electrophysiologically prior to cardiac transplantation. All 10 patients were male, aged 22 to 60years. Nine of the 10 patients had dual atrioventricular nodal pathways according to acceptedcriteria. Histologic studies of the atrioventricular conduction system showed normal structureof the atrioventricular node in all 10 hearts, with minor variations within the node in 3 cases, within the penetrating bundle in 3 cases, and within the nonbranching bundle in 3 cases. Theatrial approaches to the atrioventricular node were generally scanty in 6 hearts. The solitarycase that was shown electrophysiologically to lack dual pathways had no obvious difference inthe structure of the nodal area other than sparsity of transitional cells. We were unable tolocate any extranodal atrial tracts as described by other investigators.
Conclusion: The anatomical substrate for conduction over dual pathways may he too subtleto be detected by gross morphologic studies. Since dual pathways were unmasked in allpatients but one during electrophysiologic studies, it may be that the potential for these pathways is ubiquitous.