Acetylcholine mediated vasodilatation in the microcirculation of patients with chronic fatigue syndrome

The aetiology of chronic fatigue syndrome (CFS) remains controversial and a number of hypotheses have been put forward to explain it. Research into the condition is hindered by the considerable heterogeneity seen across patients but several reports have highlighted disturbances to cholinergic mechanisms in terms of central nervous system activity, neuromuscular function and autoantibodies to muscarinic cholinergic receptors. This paper examines an altogether separate function for acetylcholine and that is its role as an important and generalized vasodilator. Most diseases are accompanied by a blunted response to acetylcholine but the opposite is true for CFS. Such sensitivity is normally associated with physical training so the finding in CFS is anomalous and may well be relevant to vascular symptoms that characterise many patients. There are several mechanisms that might lead to ACh endothelial sensitivity in CFS patients and various experiments have been designed to unravel the enigma. These are reported here.

Immunotherapy with Mycobacterium vaccae and peripheral blood flow in long-treated leprosy patients, a randomised, placebo-controlled trial

OBJECTIVE

to evaluate immunotherapy as a means of improving peripheral blood flow in chronic leprosy patients.

DESIGN

this was a double-blind, randomised, placebo-controlled, clinical trial.

MATERIALS

heat-killed Mycobacterium vaccae 1mg plus 0.02 microg Tuberculin protein per 0.1 ml dose in borate buffer, with saline as placebo. Those studied were 92 long-treated residents of a leprosy centre in Iran, 10 of their healthy children and 10 staff members. Evaluation employed the Perimed PF2, Laser-Doppler Flowmeter, a platinum skin thermistor, and a thermal sensibility tester.

METHODS

single intradermal injections of test or placebo were given to 103 patients 18 months before the blinded evaluation. Fingerpulp blood flux was measured in controlled conditions and vasomotor reflexes and skin sensation to touch, pain and heat were evaluated in 45 and 47 patients in the placebo and M. vaccae groups, respectively, and in 20 healthy control persons.

RESULTS

Laser-Doppler flux, skin temperature, vasomotor reflexes and sensation were impaired in leprosy patients. Immunotherapy improved (p < 0.05) Laser-Doppler flux, skin temperature and temperature sensation.

CONCLUSIONS

immunotherapy, given 18 months earlier, significantly improved blood flow and temperature sensation, in fully-treated, chronic, leprosy patients. The same principles might be employed in other conditions of reduced peripheral blood flow.

Spiritual healing as a therapy for chronic pain: a randomized, clinical trial

Spiritual healing is a popular complementary and alternative therapy; in the UK almost 13000 members are registered in nine separate healing organisations. The present randomized clinical trial was designed to investigate the efficacy of healing in the treatment of chronic pain. One hundred and twenty patients suffering from chronic pain, predominantly of neuropathic and nociceptive origin resistant to conventional treatments, were recruited from a Pain Management Clinic. The trial had two parts: face-to-face healing or simulated face-to-face healing for 30 min per week for 8 weeks (part I); and distant healing or no healing for 30 min per week for 8 weeks (part II). The McGill Pain Questionnaire was pre-defined as the primary outcome measure, and sample size was calculated to detect a difference of 8 units on the total pain rating index of this instrument after 8 weeks of healing. VASs for pain, SF36, HAD scale, MYMOP and patient subjective experiences at week 8 were employed as secondary outcome measures. Data from all patients who reached the pre-defined mid-point of 4 weeks (50 subjects in part I and 55 subjects in part II) were included in the analysis. Two baseline measurements of outcome measures were made, 3 weeks apart, and no significant differences were observed between them. After eight sessions there were significant decreases from baseline in McGill Pain Questionnaire total pain rating index score for both groups in part I and for the control group in part II. However, there were no statistically significant differences between healing and control groups in either part. In part I the primary outcome measure decreased from 32.8 (95% CI 28.5-37.0) to 23.3 (16.8-29.7) in the healing group and from 33.1 (27.2-38.9) to 26.1 (19.3-32.9) in the simulated healing group. In part II it changed from 29.6 (24.8-34.4) to 24.0 (18.7-29.4) in the distant healing group and from 31.0 (25.8-36.2) to 21.0 (15.7-26.2) in the no healing group. Subjects in healing groups in both parts I and II reported significantly more 'unusual experiences' during the sessions, but the clinical relevance of this is unclear. It was concluded that a specific effect of face-to-face or distant healing on chronic pain could not be demonstrated over eight treatment sessions in these patients.

Location bias in controlled clinical trials of complementary/alternative therapies

To systematically investigate location bias of controlled clinical trials in complementary/alternative medicine (CAM).

METHODS

Literature searches were performed to identify systematic reviews and meta-analyses, which were used to retrieve controlled clinical trials. Trials were categorised by whether they appeared in CAM-journals or mainstream medical (MM)-journals, and by their direction of outcome, methodological quality, and sample size.

RESULTS

351 trials were analysed. A predominance of positive trials was seen in non-impact factor CAM- and MM-journals, (58) / (78) (74%) and (76) / (102) (75%) respectively, and also in low impact factor CAM- and MM-journals. In high impact factor MM-journals there were equal numbers of positive and negative trials, a distribution significantly (P < 0.05) different from all other journal categories. Quality scores were significantly lower for positive than negative trials in non-impact factor CAM-journals (P < 0.02). A similar trend was seen in low-impact factor CAM journals, but not to a level of significance (P = 0.06). There were no significant differences between quality scores of positive and negative trials published in MM-journals, except for high impact factor journals, in which positive trials had significantly lower scores than negative trials (P = 0.048). There was no difference between positive and negative trials in any category in terms of sample size.

CONCLUSION

More positive than negative trials of complementary therapies are published, except in high-impact factor MM-journals. In non-impact factor CAM-journals positive studies were of poorer methodological quality than the corresponding negative studies. This was not the case in MM-journals which published on a wider range of therapies, except in those with high impact factors. Thus location of trials in terms of journal type and impact factor should be taken into account when the literature on complementary therapies is being examined.

A randomized trial of distant healing for skin warts

PURPOSE

Distant healing, a treatment that is transmitted by a healer to a patient at another location, is widely used, although good scientific evidence of its efficacy is sparse. This trial was aimed at assessing the efficacy of one form of distant healing on common skin warts.

SUBJECTS AND METHODS

A total of 84 patients with warts were randomly assigned either to a group that received 6 weeks of distant healing by one of 10 experienced healers or to a control group that received a similar preliminary assessment but no distant healing. The primary outcomes were the number of warts and their mean size at the end of the treatment period. Secondary outcomes were the change in Hospital Anxiety and Depression Scale and patients' subjective experiences. Both the patients and the evaluator were blinded to group assignment.

RESULTS

The baseline characteristics of the patients were similar in the distant healing (n = 41) and control groups (n = 43). The mean number and size of warts per person did not change significantly during the study. The number of warts increased by 0.2 in the healing group and decreased by 1.1 in the control group (difference [healing to control] = -1.3; 95% confidence interval = -1.0 to 3.6, P = 0.25). Six patients in the distant healing group and 8 in the control group reported a subjective improvement (P = 0.63). There were no significant between-group differences in the depression and anxiety scores.

CONCLUSION

Distant healing from experienced healers had no effect on the number or size of patients' warts.

Healing as a therapy for human disease: a systematic review

OBJECTIVE

To assess, from published clinical trials, the evidence for the use of healing as a complementary medical intervention in human disease.

DESIGN

Limited to studies involving random assignment to a treatment group consisting of "healing," broadly defined, or to a concurrent control group. All randomized trials published up to the year 2000, were identified from MEDLINE, CINAHL, BIDS-EMBASE, the CISCOM complementary medicine databases and from bibliographic references of published articles. Copies of all published studies were obtained, data were extracted, and methodological quality (Jadad) scores were derived where possible.

RESULTS

Fifty-nine randomized clinical trials (RCTs) were found comparing healing with a control intervention on human participants. In 37 of these, healing was used for existing diseases or symptoms (22 existed as fully accessible published reports, 10 as dissertation abstracts only, and 5 as "preliminary" investigations with limited evidential value). The 22 full trials (10 reporting a "significant" effect of healing compared with control) constitute an extremely heterogeneous group, varying greatly in the method and duration of healing; the medical condition treated; the outcome measure employed; and the control intervention used. Many trials had a number of methodological shortcomings, including small sample sizes, and were inadequately reported. Only 8 studies (5 with a significant outcome for healing) had a maximum methodological quality score of 5, and in 10 studies this score was 3 or less. Two trials-both large scale and methodologically sound-were replicates, and each found a significant beneficial effect of intercessory prayer on the clinical progress of cardiac patients. Eleven of the 15 dissertation abstracts and pilot studies reported nonsignificant results for healing compared with control, a finding that probably reflects the relatively small sample sizes and the likelihood of type II errors. The significant heterogeneity found in this group of trials makes categorization problematic and inhibits the pooling of results by meta-analysis or similar techniques to obtain a global estimate of the "treatment effect" of healing.

CONCLUSIONS

No firm conclusions about the efficacy or inefficacy of healing can be drawn from this diverse group of RCTs. Given the current emphasis on evidence-based medicine, future investigations should be adequately powered, appropriately controlled, and properly described. These future investigations would most usefully consist of: (1) pragmatic trials of healing for undifferentiated conditions on patients based in general practice and (2) larger RCTs of distant healing on large numbers of patients with well-defined measurable illness.

Hypnotherapy for smoking cessation

BACKGROUND

Hypnotherapy is widely promoted as a method for aiding smoking cessation. It is proposed to act on underlying impulses to weaken the desire to smoke or strengthen the will to stop.

OBJECTIVES

The objective of this review was to evaluate the effects of hypnotherapy for smoking cessation.

SEARCH STRATEGY

We searched the Cochrane Tobacco Addiction Group trials register.

SELECTION CRITERIA

We considered randomised trials of hypnotherapy which reported smoking cessation rates at least six months after the beginning of treatment.

DATA COLLECTION AND ANALYSIS

Two reviewers extracted data on the type of subjects, the type and duration of the hypnotherapy, the nature of the control group,the outcome measures, method of randomisation, and completeness of follow-up. The main outcome measure was abstinence from smoking after at least six months follow-up in patients smoking at baseline. We used the most rigorous definition of abstinence in each trial, and biochemically validated rates where available. Subjects lost to follow-up were counted as smokers. Where possible, we performed meta-analysis using a fixed effects model.

MAIN RESULTS

Nine studies compared hypnotherapy with 14 different control interventions. There was significant heterogeneity between the results of the individual studies, with conflicting results for the effectiveness of hypnotherapy compared to no treatment or to advice. We therefore did not attempt to calculate pooled odds ratios for the overall effect of hypnotherapy. There was no evidence of an effect of hypnotherapy compared to rapid smoking or psychological treatment.

REVIEWER'S CONCLUSIONS

We have not shown that hypnotherapy has a greater effect on six month quit rates than other interventions or no treatment. The effects of hypnotherapy on smoking cessation claimed by uncontrolled studies were not confirmed by analysis of randomised controlled trials.

Articles on complementary medicine in the mainstream medical literature: an investigation of MEDLINE, 1966 through 1996

OBJECTIVE

To investigate the growth of interest, if any, in complementary or alternative medicine by the professional scientific community from the number of MEDLINE-listed and clinical trial-type articles for January 1, 1966, through December 31, 1996.

METHODS

Systematic literature searches of the MEDLINE database, using the expanded terms "alternative medicine," "traditional medicine," "acupuncture," "homeopathy," and "chiropractic," were conducted in January 1998 to evaluate the number of all articles. The number of clinical trial-type articles on the above was obtained by conducting searches for those indexed as 1 or more of the following publication types: clinical trial; clinical trial phase 1, 2, 3, or 4; controlled clinical trial; metaanalysis; randomized controlled trial; and limited to "human" trials only.

RESULTS

Articles indexed as alternative medicine formed a small proportion (0.4%) of the total number of MEDLINE-listed articles throughout the period studied. From 1966 through 1996, the total number of articles listed in MEDLINE rose significantly to a peak of 400000 additions per annum in 1996 (r = 0.97; P<.001). By contrast, the number of articles indexed under alternative medicine rose progressively only from 1972 through 1986 and since then has been relatively stable at around 1500 additions per annum. For this period, the proportion of clinical trial-type alternative medicine articles was low (mean, 2.1% per annum) but increased significantly from 1987 through 1996, reaching around 10% of the total in 1996 (r = 0.79; P<.001). Patterns of growth in the number of publications for individual therapies have varied during the period studied, and clinical trial-type articles form only a small part of any increase.

CONCLUSIONS

Interest in and awareness of complementary medicine among orthodox health care professionals has increased in the past 30 years. The increase in the number and proportion of reports of clinical trials indicates an increasing level of original research activity in complementary medicine and suggests a trend toward an evidence-based approach in this discipline. The cumulative number of clinical trial-type articles is small, however, and more high-quality original research in complementary medicine is required.

Randomized, double-blind trial of chitosan for body weight reduction

BACKGROUND

Overweight and obesity is a prevalent and costly threat to public health. Compelling evidence links overweight and obesity with serious disorders such as cardiovascular diseases and diabetes. Dietary regimen are notoriously burdened with poor compliance. Chitosan is promoted in the US and other countries as an oral remedy to reduce fat absorption and has now been incorporated as a major constituent into several over-the-counter remedies. The primary aim of this study is to investigate the clinical effectiveness of oral chitosan for body weight reduction.

METHODS

Thirty-four overweight volunteers were included in a randomized placebo-controlled double-blind trial. Subjects were assigned to receive either four capsules of chitosan or indistinguishable placebo twice daily for 28 consecutive days. Measurements were taken at baseline, after 14 and 28d of treatment. Subjects maintained their normal diet and documented the type and amount of food consumed. Adverse effects were assessed and compliance monitored.

RESULTS

Data from 30 subjects were entered into an intention-to-treat analysis. After four weeks of treatment, body mass index, serum cholesterol, triglycerides, vitamin A, D, E and beta-carotene were not significantly different in subjects receiving chitosan compared to those receiving placebo. Vitamin K was significantly increased after four weeks in the chitosan group compared with placebo (P<0.05). Compliance was 91.5% and 96.0% for chitosan and placebo groups respectively.

CONCLUSION

The above data suggest that chitosan in the administered dosage, without dietary alterations, does not reduce body weight in overweight subjects. No serious adverse effects were reported.

Different standards for reporting ADRs to herbal remedies and conventional OTC medicines: face-to-face interviews with 515 users of herbal remedies

AIMS

To determine whether adverse drug reactions (ADRs) to herbal remedies would be reported differently from similar ADRs to conventional over-the-counter (OTC) medicines by herbal-remedy users.

METHODS

Face-to-face interviews (using a structured questionnaire) with 515 users of herbal remedies were conducted in six pharmacy stores and six healthfood stores in the UK. The questionnaire focused on the likely course of action taken by herbal-remedy users after experiencing an ADR associated with a conventional OTC medicine and a herbal remedy.

RESULTS

Following a 'serious' suspected ADR, 156 respondents (30.3%) would consult their GP irrespective of whether the ADR was associated with the use of a herbal remedy or a conventional OTC medicine, whereas 221 respondents (42.9%) would not consult their GP for a serious ADR associated with either type of preparation. One hundred and thirty-four respondents (26.0%) would consult their GP for a serious ADR to a conventional OTC medicine, but not for a similar ADR to a herbal remedy, whereas four respondents (0.8%) would consult their GP for a serious ADR to a herbal remedy, but not for a similar ADR to a conventional OTC medicine. Similar differences were found in attitudes towards reporting 'minor' suspected ADRs.

CONCLUSIONS

Consumers of herbal remedies would act differently with regard to reporting an ADR (serious or minor) to their GP depending on whether it was associated with a herbal remedy or a conventional OTC medicine. This has implications for herbal pharmacovigilance, particularly given the increasing use of OTC herbal remedies. The finding that a high proportion of respondents would not consult their GP or pharmacist following ADRs to conventional OTC medicines is also of concern.

Laser Doppler perfusion imaging of skin blood flow using red and near-infrared sources

At present, scanning laser Doppler imaging uses a 633-nm helium-neon laser (RED) as the only light source, but this restricts its ability to measure blood flow (i) at darkly pigmented skin and (ii) from deeper or subdermal structures. Because near-infrared (NIR) light is known to penetrate deeper into tissue and to be less absorbed than RED, two imagers were adapted to include a NIR laser diode source (one of 830 nm for UK studies; one of 780 nm for leprosy field trials) in parallel with the existing RED source. In human hands representing a range of skin pigmentations, RED scans were unobtainable at the darkest areas of skin, but intact NIR scans could be collected in all cases. In experiments at the rat knee and the dorsal human hand, NIR and RED values were similar on normal skin. Over underlying vessels, however, NIR values greatly exceeded RED values, an effect abolished by occlusion. Similarly, in patients with leprosy and in healthy controls in Spain, fingerpulp NIR values exceeded RED values to the greatest degree when thermoregulatory flow was highest, i.e., when the deeper-lying arteriovenous anastomoses were open. Over areas of experimental inflammation, NIR gave higher values and also exhibited a greater degree of spatial heterogeneity than RED. We conclude that some current limitations of laser Doppler imaging technology can be overcome by the use of NIR laser diode sources.

Laser Doppler perfusion imaging of proximal interphalangeal joints in patients with rheumatoid arthritis

OBJECTIVE

A non-invasive imaging technique (laser Doppler perfusion imaging-LDI) based on measurement of backscattered Doppler-broadened near infra-red laser radiation was used to provide two-dimensional images of perfusion over the proximal interphalangeal (PIP) joints of a group of normal subjects compared to a group of patients with rheumatoid arthritis (RA).

RESULTS

Some PIP joints of the RA group showed areas of increased perfusion whereas normal subjects showed much less variation in perfusion between joints. These hyperaemic areas arose from the underlying joint, as scans taken with a less penetrating red laser did not show such areas.

CONCLUSION

Apart from its obvious dermatological uses, LDI could be employed to image hyperaemia associated with a variety of inflammatory conditions affecting subcutaneous structures.

Sympathetic vasomotor dysfunction in leprosy patients: comparison with electrophysiological measurement and qualitative sensation testing

Testing of skin vasomotor reflexes (VRs) by laser Doppler flowmetry (LDF) is now a recognised method of measuring peripheral dysautonomia. To assess its specificity as an indicator of impairment to unmyelinated autonomic fibres, VR testing at the fingerpulp was compared with standard qualitative sensation (QST) and with sensory electrophysiological (SNVC) measurements in 39 Iranian leprosy patients. There was a significant relationship between VR and SNCV values (but not QST): these were jointly measurable in 38.5% of fingers, and jointly absent in 35.3% of fingers which also showed significantly reduced LDF perfusion and skin temperatures. However, in 10.3% of fingers, predominantly index and otherwise apparently healthy, VRs were absent but SNCV present, suggesting early sub-clinical autonomic impairment. In a further 16% of fingers, predominantly ulnar and with poor microcirculation, intact (though impaired) VRs could be recorded despite the absence of SNCV responses, suggesting sparing or regeneration of these fibres. This evidence suggests that where there is heterogeneity of nerve damage a combination of VR and electrophysiological testing can indicate the functional status of distinct fibre types.

Effects of treatment on the histopathology of leprosy

AIMS

To identify the histological changes in leprosy skin lesions over the first few weeks after the start of leprosy treatment and to examine their relationship to reversal reaction.

METHODS

Sequential skin biopsy during treatment with multiple drug therapy. In this study, a series of 28 patients was studied, from whom two or more biopsies were taken at two week intervals. Fourteen patients had paucibacillary leprosy (PBL) and 14 had multibacillary leprosy (MBL).

RESULTS

In most cases, granuloma fraction and bacterial index fell during treatment, the bacterial index being less sensitive than the granuloma fraction. Since the biopsies were fixed in buffered formalin and processed through to paraffin wax, little immunohistochemistry was feasible. However, there was strong evidence of immune activation, with increased expression of HLA-DR in the granulomas of MBL and PBL cases: the epidermis also expressed HLA-DR in several patients. Such changes may reflect gamma IFN production from granuloma lymphocytes. Patients with reversal reaction often showed HLA-DR expression on admission which decreased with corticosteroid treatment.

CONCLUSIONS

The results suggest that activation of cell mediated immunity in leprosy lesions occurs during treatment with multiple drug therapy and may not be restricted to those with clinical evidence of reversal reaction.

Circulation and sensation at the fingertips of claw hands

Measurements of skin blood flow (by laser Doppler flowmetry) and temperature were made under environmental conditions promoting peripheral vasodilatation at the fingertips of a disfigured 'clawed' hand in 12 leprosy patients long-resident at Baba Baghi Leprosy Hospital, Tabriz, Iran. Sensory function was assessed by measuring the responses to light touch, pain and temperature of each finger, and peripheral autonomic function was gauged by estimating palmer sweating and by measuring skin vasomotor reflexes in response to inspiratory gasp. In 2 patients all measured fingers had laser Dopper flux (LDFlux) values and skin temperatures lower than the 95% confidence limits for the mean of 20 healthy controls, i.e. were impaired; in 2 patients all fingers had normal values for LDFlux and temperature; and in 8 patients there was a combination of impairment with most fingers normal for these parameters but with the small finger most commonly impaired. There were 10 (67%) fingers with impaired LDFlux and temperature values who had significant sensory impairment, whereas only 5 (18%) of the fingers with normal LDFlux values and temperatures had a similar sensory deficit. Overall, the fingers with the most impaired sensation had significantly (P < 0.05) lower LDFlux and temperature values than those with no sensory deficit. Microcirculatory impairment was not related to disordered skin vasometer reflexes or dysfunction of sweating. We concluded that the relationship between motor (skeletal muscle) nerve paralysis and any subsequent sensory neuropathy and/or microcirculatory impairment is more complex than might be expected from previous understanding of the disease.

Effect of hyperoxia at 1 and 2 ATA on hypoxia and hypercapnia in human skin during experimental inflammation

Transcutaneous PO2 and PCO2 measurements and estimates of skin respiration were monitored at different levels of inspired PO2 in 20 healthy adults during the first 4 days of the tuberculin reaction, a convenient model of acute inflammation. Hyperoxia at 1 and 2 ATA significantly increased transcutaneous PO2 levels in undisturbed and in inflamed skin but did not fully correct the relative hypoxia at the site of inflammation. Hypercapnia was reduced with O2 breathing at 2 ATA. The apparent rate of O2 consumption at the reaction site was raised during hyperoxia, most prominently at 2 ATA. The most intense reactions showed a central relative slowing of laser-Doppler blood flow indicative of microcirculatory impairment. The extent of the relative hypoxia and hypercapnia was greatest in these strongest reactions. The density of lymphocytes and monocytes in biopsies of 48-h reactions was loosely related to the corresponding transcutaneous PO2 measurements. The present study provides evidence that diffusion barriers, in addition to increased local respiration, can contribute to the apparent hypoxia and hypercapnia of this inflammatory model.

A preliminary assessment of laser Doppler perfusion imaging in human skin using the tuberculin reaction as a model

Laser Doppler imaging is a new development in the field of laser Doppler flowmetry. We were recently loaned the Lisca laser Doppler perfusion imager (LDI) manufactured by Lisca Development, Linkoping, Sweden for assessment against other methods for assessment of skin perfusion. In order to evaluate the device, it was applied to imaging flux changes induced in human skin during the tuberculin reaction. Flux values were compared directly with those from conventional lightguide laser Doppler flowmetry, and parameters measured using two other methods for assessment of tissue perfusion, dynamic thermographic imaging and tissue spectrophotometry. The results showed very good correlations between the various methods. In addition, the LDI showed that very large differences in flux values (up to 5 V) could be found within distances of only 2 mm during the tuberculin reaction and that focal centres of low flux values surrounded by higher values ('craters') could be found not only at the centre, but elsewhere in the lesion. The LDI enables rapid non-invasive detailed analysis of blood flow patterns in skin and correlates well with other methods for measuring skin perfusion. Its use to examine heterogeneity of microvascular blood flow patterns may lead to further understanding of the local mechanisms for regulation of oxygen supply to tissue.

Dynamic thermographic imaging for estimation of regional perfusion in the tuberculin reaction in healthy adults

A sensitive method for measurement of the volume of blood flow through the skin, based on the kinetics of reheating after localised cooling, is described in this paper. This method has been used to study the tuberculin reaction as a model of cutaneous delayed-type hypersensitivity (DHS) in man. Over the positive reaction there is accelerated reheating similar in kinetics and extent to that seen after maximal hyperaemia induced by intradermal injection of histamine or prostaglandin E2. The earlier phase of reheating (10-100 s) is more dependent on blood flow, whereas the later phase (100-300 s) is apparently more dependent on non-perfusion heat exchange mechanisms, including conduction. The reheat kinetic method is largely dependent on blood flow in the deep dermal vessels (diameter > 50 microns), whereas the alternative approach of measurement of the velocity of flow of erythrocytes in the microcirculation by laser Doppler (LD) flowmetry gives results biased towards the most superficial dermal circulation. Previous studies with LD flowmetry have shown that the blood velocity is greatest at the centre of weak and strong reactions, while in the most intense reactions it is raised at the centre but maximal at the periphery (central relative slowing, CRS) raising the possibility of central ischaemia. The reheat kinetics approach has now indicated that the deep dermal circulation is not impaired in CRS reactions. It is concluded that there must be partial obstruction of the parts of the microcirculation communicating between the deep and superficial dermal plexuses, presumably from the accumulation of exudate oedema in the most intense tuberculin reactions.

Vasomotor reflexes in the fingertip skin of patients with type 1 diabetes mellitus and leprosy

Fingertip skin blood flow was measured by laser Doppler flowmetry (as LDflux) under environmental conditions promoting vasodilation in Scottish patients with diabetes mellitus and Indian patients with leprosy. The reflex control of fingertip blood flow was assessed by measuring the reduction in LDflux induced by deep inspiratory gasp (IG) and cold challenge (CC) of immersing the contralateral hand in cold water. The uncomplicated diabetic patients showed normal vasomotor reflexes and an increased, though non significant, LDflux level (p < 0.06). The patients with diabetic neuropathy had resting LDflux levels significantly less than the uncomplicated group and also had substantial impairment of both IG and CC reflexes. Those with retinopathy (but no clinically apparent neuropathy) had LDflux within the normal range, but they showed minor evidence of impairment of the vasomotor reflexes. The uncomplicated newly registered leprosy patients had reduced LDflux and substantial impairment of CC reflexes. These changes were more marked in newly registered leprosy patients with clinical evidence of neuropathy. Leprosy patients with long-standing neuropathy requiring orthopaedic treatment had LDfluxes so greatly reduced that measurement of vasomotor reflexes was not practicable. The CC reflex was more severely affected than the IG reflex and more frequently absent in leprosy patients, possibly because of associated sensory neuropathy affecting the afferent limb of this response. Thus laser Doppler flowmetry can detect impairment of reflex control of fingertip blood flow in both diabetes mellitus and leprosy, but there are functional differences in the pattern of autonomic impairment between the diseases, suggesting differences in the pathogenesis of nerve damage.

Biological zero in laser Doppler measurements in normal, ischaemic and inflamed human skin

The Biological Zero (BZ) signal in laser Doppler flowmetry was recorded during temporary occlusion of the arterial circulation to the limb by a blood pressure cuff inflated suprasystolically for 2 min. The non-thermoregulatory skin at the ankle was compared with the thermoregulatory skin over the toe pad in patients with lower limb arterial obstructive disease, elderly controls without arterial disease and young healthy adults under cool (15-17 degrees C) and warm (25-27 degrees C) ambient conditions. The absolute BZ values did not differ significantly within the three groups at the two room temperatures. However the resting laser Doppler flowmetry signal (LDflux) was consistently higher under warm than cold room temperatures: these differences were much greater at the toe than at the ankle. Accordingly, the relative size of BZ, expressed as a percentage of the resting LDflux, was least over the toe in a warm room (5-10%) and greatest over the malleolus (59-83%) in the cold room. The changes during the evolution of a positive tuberculin skin reaction were followed as a model of chronic inflammation in man. The resting LDflux rose 10 fold (from 0.3 to 3.4V) while the change in the BZ was minor (0.16-0.2V). Thus the rise in LDflux in a fully developed tuberculin reaction was approximately 30X greater than that for the corresponding BZ. Concurrent measurements of the alternative output from the laser Doppler flowmeter (CMBC) showed in a similar pattern. Since the BZ signal can be a substantial proportion of the resting LDflux measurement, we support the recommendation that the BZ should be measured wherever possible and practicable, for subtraction from the observed LDflux to assess the true flow: 'raw' LDflux measurements should be interpreted with extreme caution, particularly at relatively low resting LDflux levels.

Cold fingers in leprosy

Under conditions of maximal thermoregulatory peripheral dilatation, most healthy subjects (both Indian and European) showed raised blood flow in the fingertips (measured by laser Doppler flowmetry) where the skin temperature is only slightly lower than the core body temperature. Most borderline lepromatous (BL) leprosy patients had much colder fingers and the blood flow was slow: borderline tuberculoid (BT) patients had skin temperatures similar to those seen in healthy subjects, but their fingertip blood flow was reduced relative to that in control subjects. The occurrence of cold fingers and slow blood flow was clearly associated with evidence of sensory impairment to light touch, pressure and temperature. Slower fingertip blood flow was strongly associated with impairment of vasomotor control in this anatomical region, suggesting that both may be a consequence of leprosy peripheral neuropathy, at least in patients with early leprosy, but it is likely that leprosy arteriopathy may contribute to the lowered peripheral perfusion in advanced cases. It is suggested that the simple clinical sign of cold fingers may be of value in the preliminary assessment of patients presenting at any leprosy control clinic in the tropics.

Spectrophotometric measurements of haemoglobin saturation and concentration in skin during the tuberculin reaction in normal human subjects

A non-invasive technique employing light-guide spectrophotometry is described for the measurement of haemoglobin concentration and oxygenation in human skin. Measurements were carried out in the visible wavelength range (500-620 nm) and a series of experiments were carried out in vitro and in vivo in order to calibrate the system. Indices were derived for the measurement of relative haemoglobin concentration and absolute oxygen saturation. The technique was applied to measure the changes in these parameters occurring during the course of the tuberculin reaction in human skin. The results are compared with those from laser Doppler flowmetry and transcutaneous oxygen measurements which were carried out concurrently. Divergence between the intracapillary and tissue oxygenation during the course of the reaction provides evidence for the existence of increased diffusion resistance for oxygen; a model is proposed. The study demonstrates the potential clinical usefulness of light-guide spectrophotometry for the non-invasive investigation of tissue oxygen supply.

Circulatory adaptation to the increased metabolism in the skin at the site of the tuberculin reaction

The sequence of changes at the site of a positive tuberculin test response were studied in 19 healthy young adults who had been immunised with BCG in childhood. The development of erythema preceded that of induration and both were most intense at 48-72 h. The strongest reactions showed higher laser Doppler (LD) flux at the periphery than at the center (central relative slowing). All showed a substantial reduction in steady-state (ss) tcpO2 from 24 h onwards and the oxygen consumption rate (mlO2.kg-1.min-1), calculated from the rate of fall in tcpO2 during temporary cuff occlusion of arterial input, was raised (greater than two-fold) throughout the period of study (to 96 h). The density of lymphocytes and macrophages in the inflammatory infiltrate in the dermis was related to the fall in tcpO2.ss and to the extent of thickening of the dermis. These experiments showed that the previously healthy dermal microcirculation can adapt to temporary increase in metabolic demands of leucocytes emigrated from the circulation into the tissue: in intense delayed hypersensitivity (DHS) reactions there is considerable hypoxia and respiratory debt, but maintenance of viability in the short-term. It is likely that similar adaptations occur in the period of establishment of microbial infection.

Impairment of fingertip vasomotor reflexes in leprosy patients and apparently healthy contacts

Fingertip blood-flow velocity and its control by vasomotor reflexes were studied in leprosy patients and in healthy controls with a laser Doppler flowmeter. In newly registered patients, the flow was significantly lower than in the healthy controls, and even lower values were recorded in the long-standing patients with lower limb ulcers and/or deformity. The newly registered patients showed substantially impaired vasomotor reflex responses in the fingertips to cold challenge of the opposite hand or deep inspiratory gasp. Low blood flow and impairment of vasomotor reflexes were more prominent in those leprosy patients who showed clinical evidence of neuropathy and/or histological evidence of reaction in a punch biopsy of leprosy skin lesions. This aspect of dysautonomia to cold challenge was particularly prominent in apparently healthy, fully treated ex-patients. There was an unexpectedly high prevalence of impairment of vasomotor reflexes in newly registered and apparently healthy, adequately treated leprosy patients. The method is very sensitive, and it remains to be established whether the lesions it detects are nonprogressive residues, or previous nerve damage, or an indication of on-going nerve damage. A minority of leprosy contacts showed impairment of vasomotor reflexes. Those with two or more affected fingers were more likely to have had a higher level of exposure to Mycobacterium leprae than those with one or no affected fingers. The cause of this unexpected impairment of fingertip vasomotor reflexes in a minority of leprosy control workers has not yet been determined.

Impairment of vasomotor reflexes in the fingertips of leprosy patients

A method is described for eliciting fingertip vasomotor reflexes by inspiratory gasp and contralateral hand cold challenge. The results of the two tests are reproducible on replicate testing and, when taken together, have proved reliable for detection of impairment of autonomic reflexes in 10 newly registered leprosy patients who did not have any obvious deformity. Similar, but less severe, impairment of vasomotor reflexes was noted in a group of 10 fully treated, apparently cured ex-leprosy patients, none of whom showed clinically obvious neuropathy. Both the new patients and the ex-patients were significantly different from healthy contacts and from healthy Europeans, who were indistinguishable by this test. Evidence is presented suggesting that impairment of these vasomotor reflexes is mainly due to damage to the efferent pathway in the peripheral nerves. The method might prove valuable for investigation of early nerve damage in new patients or during reversal reactions in leprosy at a stage before irreversible damage is done.

Quantification of sympathetic vascular responses in skin by laser Doppler flowmetry

An improved physiological test of focal sympathetic nervous function using a laser Doppler flowmeter is presented. The test evaluates rapid reflex changes in skin blood flow at the finger tip where there are abundant arteriovenous anastomoses with dense sympathetic innervation. Indirect body heating was employed in all subjects to induce central vasodilation and to obtain stable comparable finger tip blood flows prior to stimulus. The reflex vasoconstriction which occurs following inspiratory gasp and contralateral hand cold challenge was quantified and its reproducibility investigated on three separate occasions in 20 young subjects. The variability in responses both within and between young subjects was small. The test was applied to 10 diabetic patients with autonomic neuropathy and to 10 age-matched control subjects. Vasoconstrictor reflexes were significantly lower in the diabetic group (p less than 0.005) with responses lower than 2 SD from the mean for age-matched controls. In conclusion, the test provides an assessment of focal autonomic damage which can be applied to other regions of the body rich in arteriovenous anastomoses and may have application in clinical studies investigating autonomic activity.

The effect of oxygen supplementation on post-occlusive reactive hyperaemia in human forearm skin

The effects of raised tissue oxygen levels on reactive hyperaemia (RH) in the skin following arterial occlusion of short duration were investigated. Oxygen levels were increased by breathing 100% oxygen at 1 and 2 atmospheres absolute (ATA) in a hyperbaric chamber. Superficial skin blood flow and oxygen tension were measured throughout using a laser Doppler flowmeter and a transcutaneous oxygen monitor. The basal pre-occlusion and the maximum post-occlusion blood flows (Flb and Flmax), the time taken for flow to fall to half maximum (TR1/2), and the time for flow to return to its basal level (TR) were measured. Pre- and end-occlusion transcutaneous oxygen levels were also recorded. Oxygen breathing at 1 ATA significantly reduced TR1/2 (p less than 0.05) and at 2 ATA significantly reduced TR1/2 and TR (p less than 0.005 and p less than 0.0001) compared with control measurements during air breathing at 1 ATA. Flmax was not significantly reduced breathing oxygen at 1 or 2 ATA. These findings support the view that maximum post-occlusion blood flow in superficial skin is determined mainly by myogenic mechanisms, whereas the recovery of blood flow to basal levels is influenced largely by oxygen tension. We conclude that the direct vasoconstrictor effect of high oxygen levels is small and that the faster recovery at high tissue oxygen tensions may result from a decrease in vasodilators formed during hypoxia.

Assessment of the respiratory metabolism in the skin from transcutaneous measurements of pO2 and pCO2: potential for non-invasive monitoring of response to tuberculin skin testing

A method is described for non-invasive transcutaneous (tc) measurement of tissue respiratory gas tensions in the skin on the forearm for study of delayed hypersensitivity reactions in man. Steady state values for tcpO2 and tcpCO2 were measured, and the skin respiratory rate (oxygen consumption) and the tissue pH were estimated from the changes in tcpO2 and tcpCO2 observed after interruption of the arterial circulation by cuff occlusion for 4 minutes. The extent of within-experiment and between subject variation in the steady-state measurements was not great (coefficient of variation 10%): tcpCO2.ss (steady state) was higher in men and tcpO2.ss was higher in women, but the extent of these sex differences was also small. Reference ranges have been established for tc measurements and calculated indices of tissue respiration in the undisturbed forearm skin of normal volunteers, against which the changes induced by tuberculin testing can be assessed. Severe changes, indicative of profound hypoxia and acidosis, are seen in intense delayed hypersensitivity reactions. Similar, but less severe changes were seen at the site of skin tests on BCG-vaccinated subjects who were 'negative' by conventional criteria of measurement of dermal induration and they became greatly exaggerated after successful re-vaccination. Intradermal injection of saline did not induce hypoxia or local acidosis. These new methods are very sensitive indicators of the tissue response in the DHS reaction.

The influence of histamine and PGE2-induced hyperaemia and oedema on respiratory metabolism in normal human forearm skin

Transcutaneous measurements of pO2 and pCO2 were made on the forearm skin after intradermal injection of histamine, PGE2, and saline. The mediators, used at concentrations which induce intense hyperaemia, did not modify the steady state tcpO2/pCO2 levels measured with a sensor head temperature of 44 degrees C when breathing air or hyperbaric (2ATA) oxygen. It was deduced that gas transport is unaffected by mediator-induced conditions in the skin. The rates of fall of tcpO2 and of rise of tcpCO2 after arresting the forearm circulation by cuff occlusion of the arm were significantly less at the histamine site than at the PGE2 and saline sites. The values over the PGE2 and saline injection sites were less than those over undisturbed skin. The dynamic tests of respiratory gas exchange indicate that the skin metabolic rate is reduced at all injection sites and the greatest effect was seen with histamine. Measurement of dermal thickness after saline injection has shown that the excess interstitial fluid persists at the time of maximal hyperaemia: this is further accentuated at the histamine site through active oedema formation. Accumulation of excess interstitial fluid (persistence of aqueous injection or oedema generated by the action of mediator) separates the tissue cells. The reduction in the number of cells per unit volume is sufficient to explain the observed reduction in oxygen consumption per unit volume of skin. It is concluded that the increased diffusional distances in mediator-induced oedema are unimportant for the respiration of otherwise normal tissues, but that oedema by reducing oxygen flux may contribute appreciably to the hypoxia of inflamed tissue infiltrated with metabolically active cells.