Thermal screening of facial skin arterial hot spots using non-contact infrared radiometry.

Non-contact infrared thermometry of facial skin offers advantages over less accessible internal body sites, especially when considering mass screening for febrile infectious disease. The forehead offers an obvious site, but does not present an isothermic surface, as various small arteries passing close to the surface create 'hot-spots'. The aim of this study is to use non-contact infrared (IR) thermometry to determine the link between the temperature at specific facial skin sites and clinical body temperature. A sample of 169 asymptomatic adults (age range 18-54 years) was screened with IR thermometers (Braun Thermoscan proLT for auditory meatus (AM) temperature representing clinical body temperature, and a Raytek, Raynger MX for skin surface temperature). Peak IR skin temperature was measured over the course of each posterior auricular artery (PAA) and each superficial temporal artery (STA). In a sub-group (n = 54) the peak skin temperature of the forehead's metopic region (MR) was also recorded. There were no differences (P > 0.05) between the PAA and STA at 34.2 +/- 0.9 degrees C and 34.2 +/- 0.7 degrees C, respectively, which were 2.5 degrees C cooler than the AM temperature (36.7 +/- 0.5 degrees C, p < 0.001). Although there was no correlation between AM and PAA or STA there was a correlation (r2 = 0.63, p < 0.001) between PAA and STA. There were no asymmetric temperature differences between the left and right sides and males had warmer skin over the MR (F, 33.6 +/- 0.7 degrees C versus M, 34.4 +/- 0.6 degrees C, p < 0.001). Although a lack of correlation between either PAA or STA and AM was apparent in asymptomatics, further research in symptomatics is required to determine the usefulness of these measurements in mass screening of conditions such as fever.

The vagaries of ear temperature assessment.

There have been a growing number of reports suggesting that ear temperature measurement is unreliable and by implication so is the device. Examination of the measurement site, the tympanic membrane (eardrum) and the walls of the external auditory meatus (ear canal) reveals that at least some of the unreliability might derive from poor aiming of the infrared thermometer: the ear canal walls have a lower temperature than the eardrum. Additionally, anatomical properties of the ear canal may increase the difficulty of aiming the thermometer at the eardrum. Furthermore, the rich vascularization, innervation and variations in skin properties (thickness, oil secretion and hair) along the length of the ear canal affect the black body-like nature of the structure. It is concluded that such factors are more likely underlying reasons for the difficulties in reliably reproducing temperatures from this site. We conclude that concerns should extend beyond the reliability of the device and there should be greater study of the measurement site. The argument extends to all sites chosen for clinical assessment of the patient, as previous studies of the alternative temperature measurement sites are also unfortunately few and tend to be lacking in scientific rigour.

The effect of factors such as handedness, sex and age on body temperature measured by an infrared 'tympanic' thermometer.

BACKGROUND: The effectiveness of IRET has been called into question. However, there are a number of factors that might affect ear temperature measurement. Some of these are the focus of this study. METHOD: 366 asymptomatic subjects (0.75 to 53 years old) volunteered to take part in this ethically approved study. The data were analysed in respect to handedness, sex and age. RESULTS: Two-way ANOVAs showed significant interactions between age group and sex (first ear measured, p = 0.017; second p = 0.298), and between handedness and sex (first ear measured, p = 0.011; second p = 0.040) in relation to their ear temperature. Ear temperatures of males tended to be lower than females, however this only found significance in the 'Early Puberty' age group (p < 0.001). DISCUSSION: Significant differences in ear temperature were seen for handedness, sex and age. CONCLUSION: We have shown that handedness, sex and age might be contributory factors to ear temperature differences in the population.

Differing action potential shapes in rat dorsal root ganglion neurones related to their substance P and calcitonin gene-related peptide immunoreactivity.

Intracellular electrophysiological recordings were made in vitro at 36.5 degrees C from lumbar (L4 to L6) dorsal root ganglion neurones of 6-8-week-old female rats. Electrophysiological properties were recorded prior to intracellular injection with fluorescent dye. The following showed substance P-like immunoreactivity (SP-LI): 8/19 C-fibre cells, 6/26 Adelta cells, and 0/52 Aalpha/beta cells. In C-fibre neurones, there were no significant differences in action potential (AP) characteristics between those with SP-LI and those without. In contrast, the Adelta neurones with SP-LI had significantly deeper and longer afterhyperpolarisations (AHPs), but their AP durations did not differ from those without SP-LI. Both SP-LI and calcitonin gene-related peptide-LI (CGRP-LI) were examined on 18 Adelta and 11 C cells. Most (7/8) neurones with SP-LI also showed CGRP-LI, but only 7/21 neurones without SP-LI showed CGRP-LI. One C cell showed SP-LI but no CGRP-LI. Neurones with neither peptide (-/-), with only CGRP (-/CGRP) or with both peptides (SP/CGRP) were compared (n = 28). The numbers in each group were, respectively, 5, 2, and 3 with C-fibres and 9, 5, and 4 with Adelta-fibres. The peptide content and AP shape were related in Adelta neurones. Most -/- Adelta neurones had short APs and short AHPs; most -/CGRP neurones had long APs and long AHPs, and SP/CGRP neurones had short APs with deep, long AHPs. There was a positive correlation between log10 of the area under the AP (AP area) and log10 AHP duration in Adelta neurones. All SP- and most CGRP-containing Adelta neurones had AP shapes similar to those previously described for nociceptive neurones. However, a few without peptide also showed such properties, raising the possibility that some nociceptive neurones did not express these peptides.

Electrophysiological properties of neurones with CGRP-like immunoreactivity in rat dorsal root ganglia.

Intracellular voltage recordings and fluorescent dye injections were made in vitro in 107 neurons in lumbar dorsal root ganglia (DRGs) of 6- to 8-week-old rats. Calcitonin gene-related, peptide-like immunoreactivity (CGRP-LI) was examined in these neurones, which were divided into C-, A delta-, and A alpha/beta-fibre neurones on the basis of their conduction velocities (CVs). A-fibre neurones with CGRP-LI had significantly longer mean action potential (AP) and afterhyperpolarisation (AHP) durations than those without CGRP-LI. A delta neurones with CGRP-LI had significantly longer AHP durations, slower CVs and slower maximal fibre following frequencies than those without CGRP-LI. They also had longer AP durations (not significant). The largest A delta neurones were CGRP-LI negative, whereas the smaller cells were either positive or negative. A alpha/beta neurones with CGRP-LI also had longer mean APs (not significant) and AHPs (significant) than those without CGRP-LI, and the cell size distributions were similar for positive and negative neurones. Most A-fibre neurones with CGRP-LI had inflections on the falling phase of the somatic AP. Of the A-fibre neurones with such inflections (Ai neurones), those with CGRP-LI had longer AP durations (not significant) and longer AHP durations (significant) than Ai neurones without CGRP-LI, pointing to a functionally distinct subgroup of Ai neurones. There were no significant differences in electrophysiological properties or cell size measurements between C-fibre neurones with and without detectable CGRP-LI. The patterns of electrophysiological properties of A delta neuronal somata with CGRP-LI and of most, but not all, A alpha/beta neuronal somata with CGRP-LI are similar to those reported for cutaneous nociceptors with A fibres in rat (Ritter and Mendell [1992] J. Neurophysiol. 68:2033-2041). Because rat DRG neurones that express CGRP normally also express trkA (Averill et al. [1995] Eur. J. Neurosci. 7:1484-1494), the properties described here of neurones with CGRP-LI are probably the same as those of DRG neurones with trkA.

Cell type and conduction velocity of rat primary sensory neurons with substance P-like immunoreactivity.

A double labelling immunohistochemical study of rat L4 dorsal root ganglia was made with an anti-substance P antibody and with an antibody, RT97, which specifically labels the light cell population. Substance P-like immunoreactivity was found in 30% of the small dark neurons and 10% of the light neurons. Of the neurons with substance P-like immunoreactivity, 30% were light neurons and 70% were small dark neurons. A study of electrophysiologically characterized neurons in lumbar dorsal root ganglia with dye injection revealed substance P-like immunoreactivity in neurons with conduction velocities ranging from 0.5 to 9.5 m/s. It was seen in 50% of C-fibre neurons, in 20% of A delta-fibre neurons, and in no A alpha/beta neurons. Overall, substance-P-like immunoreactivity was found in 10% of A-fibre neurons sampled.

Cell type and conduction velocity of rat primary sensory neurons with calcitonin gene-related peptide-like immunoreactivity.

An immunocytochemical double labelling study of L4 dorsal root ganglia from rats aged seven to 10 weeks was made with an antibody to calcitonin gene-related peptide and with RT97, an anti-neurofilament antibody which specifically labels the light neuron population. Peptide immunoreactivity was found in an average of 46.5% of all neurons. Sixty-two per cent of the small dark (RT97-negative) and 30% of the light (RT97-positive) neuron populations contained the peptide. About one-third (32%) of the cells with peptide immunoreactivity were light cells and about two-thirds (68%) were small dark cells. Intracellular electrophysiological recordings were made in vitro from neurons in lumbar (L4, L5 and L6) dorsal root ganglia from six- to eight-week-old rats, followed by dye-injection and immunocytochemistry. This showed that conduction velocities of neurons with calcitonin gene-related peptide-like immunoreactivity ranged from 0.5 to 28.6 m/s. Seventy-three neurons were successfully processed. Of these, calcitonin gene-related peptide-like immunoreactivity was found in 46% of C-fibre neurons, 33% of A delta-fibre neurons and in 17% of the A alpha/beta-fibre neurons. The peptide-like immunoreactivity was found in approximately 25% of all A-fibre neurons sampled.

Conduction velocity changes along the processes of rat primary sensory neurons.

Conduction velocities of rat L4, L5 and L6 dorsal root ganglion neurons were measured in vitro, from several points on the peripheral nerve and dorsal root. Conduction velocities calculated from a single stimulation point (12-26 mm from the ganglion) proved accurate for fibres conducting up to 17 m/s in the peripheral nerve and up to 14 m/s in the dorsal root, but tended to underestimate the value for faster fibres. C-fibre neurons of the L4 and L5 ganglia had a unimodal distribution of conduction velocities below 1.3 m/s. These were discontinuous with A-fibre conduction velocities, which also had a unimodal distribution and had no clear A delta peak. In contrast, conduction velocities of L6 ganglion neurons showed no discontinuity between C- and A-fibres, but had a clear A delta peak. In A-fibre neurons, dorsal root conduction velocities were on average about 14% slower than, and linearly related to, those in the peripheral nerve. However, in individual neurons the dorsal root conduction velocity could be slower or faster than that in the peripheral nerve. In C-fibre neurons dorsal root conduction velocities were almost always slower (average 28%) but not correlated with those of the peripheral nerve. Slowing of conduction velocity along the sciatic nerve was seen in most fibres conducting at less than 2 m/s, but not in faster fibres. The slowing was substantial (up to 60%), sometimes from the A delta to the C-fibre range, and sudden, occurring at a distance of between 15 and 29 mm from the ganglion.

Evidence to support the peripheral branching of primary afferent C-fibres in the rat: an in vitro intracellular electrophysiological study.

Intracellular voltage recordings were made in vitro at 36.5 +/- 1 degrees C from 35 rat lumbar dorsal root ganglion (DRG) neurones with a peripheral conduction velocity (CV) in the C-fibre range (0.3-2.2 m/s). The peripheral nerve (PN) was stimulated in one of three different ways, each delivering single stimuli (0.1-1 ms duration, 2-3-times threshold; maximum 50 V) at a low frequency (0.3 Hz). With each of the three stimulation methods used here a similar proportion of cells (approximately 30%) showed changes, either an abrupt latency change or a soma invasion by two action potentials (APs). Both of these changes were consistent with branching of primary afferent C-fibres in the PN.

Choline acetyltransferase-like immunoreactivity in small diameter neurones of the rat dorsal root ganglion.

In the rat choline acetyltransferase (ChAT)-like immunoreactivity (ChAT-LI) was demonstrated in the dorsal root ganglion (DRG), in the superficial spinal cord and in the subepithelial layer of the ureter using immunohistochemical techniques. In the L1 DRG, 66% of the neurones were ChAT-LI. They did not express neurofilament immunoreactivity (RT97 negative) but could also contain calcitonin gene-related peptide-like immunoreactivity (CGRP-LI). In the superficial spinal cord and in the subepithelial plexus of the ureter--both areas where high numbers of fine afferent fibres have been demonstrated--CGRP-LI and ChAT-LI were co-distributed, indicating that ChAT can be found in the peripheral and central endings of small afferents. The data provide morphological evidence that a substantial proportion of afferent fibres are cholinergic.

Differential intracellular labelling of identified neurones with two fluorescent dyes.

Electrophysiologically characterised rat dorsal root ganglion (DRG) neurones in vitro were injected with a fluorescent dye, either ethidium bromide or Lucifer yellow. Microelectrodes filled with ethidium bromide had lower resistances and were electrically more stable than comparable electrodes filled with Lucifer yellow. Neither dye affected the electrophysiology of these neurones in this study. We have used these dyes to locate and identify unambiguously the electrophysiologically characterised neurones after histological processing. Neurones filled with ethidium bromide could easily be distinguished from those filled with Lucifer yellow, even when they were closely apposed. Preliminary data, using the antibody RT97, indicates the compatibility of ethidium bromide injection with immunocytochemical studies. Ethidium bromide promises to be an important tool for use alone and alongside Lucifer yellow in the correlation of electrophysiology with histology.

Primary sensory neurones: neurofilament, neuropeptides, and conduction velocity.

This paper reviews and provides new data on the relationship of the peptide content in rat dorsal root ganglion (DRG) neurons to a) the neurofilament content of the soma and b) the conduction velocities of the fibres. The latter involved intracellular recordings made in vitro followed by dye injection and immunocytochemistry. Because neurofilament-poor DRG neurones have C-fibres, and A-fibre neurones are neurofilament rich, the soma neurofilament content of peptide containing neurones allowed predictions to be made about their conduction velocity ranges. Substance P-like immunoreactive (SP-LI) neurones were mostly small, neurofilament poor, but a few (15%) were neurofilament rich. From conduction velocity measurements, about half the C-fibre neurones studied and 10% of A delta-neurones but no A alpha/beta-neurones showed SP-LI. CGRP-LI neurones were also mainly neurofilament poor neurones, but 32% were neurofilament rich, including small, medium, and large neurones. Fibres of CGRP-LI neurones conducted in the C, A delta or A alpha/beta ranges. Neurones with somatostatin-LI (SOM-LI) were all neurofilament poor; preliminary data is consistent with SOM-LI neurones having C-fibres.

Immunohistochemical demonstration of sensory nerve fibers and endings in lumbar intervertebral discs of the rat.

Although it is accepted that the intervertebral disc has a sensory component, it has not been previously shown by any specific method. Immunoreactivity of the physiologically active neuropeptide, calcitonin gene-related peptide (CGRP), was used as a specific marker of sensory nerve fibers and their endings in the intervertebral disc of the rat. In this study, positive fiber immunoreactivity was taken as an indication that those fibers were of sensory, and not sympathetic, origin. Immunoreactivity was found in the outer annulus fibrosus of all intervertebral discs studied. The CGRP-like immunoreactivity was also found in structures that resembled nerve endings. To the authors' knowledge, this is the first report presenting detailed positive evidence of sensory fibers and their endings in the lumbar intervertebral disc of any mammalian species.

A review of research on acupuncture for the treatment of lumbar disk protrusions and associated neurological symptomatology.

The association between acupuncture (AP) and pain relief is so strong that it has tended to obscure any other potentially significant clinical results. This review indicates the wealth of data from around the world on various aspects of AP treatment for low back syndromes related to lumbar intervertebral disk prolapse (PID). Although plentiful, the research is variable in quality, especially with respect to design, consistency, and follow-up. Even so, the large number of patients who appear to have been treated successfully (i.e., given a high degree of symptomatic relief) supports a potential role for AP. This is further supported by studies on patients who had previously had unsuccessful treatment with conservative methods. The role envisaged for AP, in cases of lumbar PID and sciatica, is at least of a supplementary therapy capable of reducing the requirement of more invasive forms of treatment. No such role is envisaged in cases of cauda equina compression where surgery must remain the treatment of choice. AP should be explored more fully, using appropriate designs, so that this discipline may achieve its full therapeutic potential in the West.

Effect of acupuncture stimulation of the auricular sympathetic point on evoked sudomotor response.

OBJECTIVES: To investigate whether stimulation of the auricular sympathetic acupuncture point would affect the mean maximum amplitude of evoked sudomotor responses. DESIGN: A placebo-controlled trial. Two types of controls were used: no acupuncture and acupuncture of an alternate "non-sympathetic nervous system" related (i.e., a non-sympathetic, placebo) point. Subjects were included in either the placebo or the test group. Each subject would have one session of acupuncture and one session without acupuncture, the acupuncture was applied in either the first or the second session. Initially, each group was unaware in which of the two sessions they would receive acupuncture (cross-over design). Each individual was unaware of which group they were to participate in. SETTINGS/LOCATION: A quiet, sealed room with a constant temperature, in the research department of the Anglo-European College of Chiropractic. SUBJECTS: Thirty-eight asymptomatic male, white volunteers (18 to 40 years old). INTERVENTIONS: The two groups underwent two electrodermal response (EDR) recording sessions, at an interval of 5 weeks. During each session, they were also presented with eight stimuli, each of which was designed to stimulate the sympathetic nervous system. In each session, subjects either received auricular acupuncture (AA) or did not. OUTCOME MEASURES: The maximum amplitude of the EDR for each stimulus. RESULTS: AA at the non-sympathetic, placebo point significantly increased EDR both with respect to the individual stimuli (p < or = 0.05 to < or = 0.001) and for the pooled data (p = 0.0001). AA to the sympathetic point produced no significant change in EDR for either individual stimuli (p range > or = 0.8 to > or = 0.1) or for the pooled data (p > 0.8). A significant difference was found between the results from placebo and sympathetic point stimulated groups during AA for 2 of the 8 stimuli (p < 0.05), and for the pooled data from all 8 stimuli (p = 0.0006). CONCLUSION: Stimulation of the sympathetic AA point significantly decreased the stimulus-evoked EDR when compared with an AA stimulation to a non-sympathetic (placebo) point. However, it did not significantly alter EDR compared with no treatment. This implies that the increase in response as a result of inserting the needles was negated by placing the electrodes in the AA sympathetic point. Consequently, one might surmise that there may be a specific action of AA in respect to hyperhidrosis resulting from an increase in sympathetic activity.

Assessment of humidity and temperature sensors and their application to seating.

Humidity and temperature are considered to be important factors in designing comfortable seat surfaces. A small number of studies have attempted to address this;however the methods used were limited regarding the placement of their sensors. This study aimed to design a sensor array system to investigate changes in humidity and temperature for eventual use in the study of factors affecting sitting comfort and incontinence detection. The system was subjected to three types of experiments: sensor response verification, thermal radiation testing and in situ trials. The variance in output within each type of sensor was small (+3.5% and +0.38 degrees C) and there was no apparent change to the variance in output of the sensors, when used in air or on a foam cushion loaded with a 50 kg sand bag (p > 0.1). In the human sitting experiments, although the profile from sensors under the thighs and ischial tuberosities were similar, the magnitude of change could be affected by position and body mass of the subject. This was especially noticeable with the sensors under the coccyx. These results support the use of multiple sites for sensor placement over the use of a single site when studying these parameters at the interface between subject and seating material at the seat base.

Sparse substance P-like immunoreactivity in intervertebral discs. Nerve fibers and endings in the rat.

I studied rat lumbar intervertebral discs using a monoclonal antibody to substance P, which revealed immunoreactivity in the periosteum and ligaments adjacent to the intervertebral disc. Fibers containing substance P-like immunoreactivity were also found penetrating and terminating within the annulus fibrosus of both the anterior and posterior intervertebral disc. The maximum depth of penetration was 5 lamellae (annular rings) or approximately one sixth of the depth of the annulus. The terminal structures were not encapsulated (free-nerve endings) and were either branched, looped or both. The majority of fibers were varicose in appearance. Substance P-like immunoreactivity was very minor.