AB1209 MECHANISTIC FACTORS CONTRIBUTING TO PAIN AND FATIGUE IN FIBROMYALGIA AND ME/CFS: AUTONOMIC AND INFLAMMATORY INSIGHTS FROM AN EXPERIMENTAL MEDICINE STUDY

Background

Fibromyalgia and ME/CFS are multifaceted conditions with overlapping symptoms(1); the pathoaetiological mechanisms are complex and debated(2), however there is a strong association with features of hereditary disorders of connective tissue (hypermobility) and autonomic and inflammatory abnormalities (1,2).

Objectives

To determine potential autonomic and inflammatory mechanisms of pain and fatigue in fibromyalgia and ME/CFS

Methods

After excluding participants with WCC higher than 10 (suggesting acute infection) baseline markers of inflammation (CRP and ESR) were available for 60 patients with confirmed diagnoses of Fibromyalgia and/ or ME/CFS and 23 matched controls. Participants then underwent full research diagnostic evaluation including a hypermobility assessment(1) and autonomic challenge (60 degree head up tilt, ISRCTN78820481). Subjective pain and fatigue were assessed before and after challenge (VAS). Linear regression models were used to explore predictors, with adjustment for confounders as appropriate. Mediation analyses (looking for mechanistic effects) were conducted according to the method of Hayes (3) and mediation considered significant if bootstrapped confidence intervals of the estimated indirect effect did not cross zero. In these mediation analyses predictor variable was group membership (patient or control), outcome variable was change in 1)pain and 2)fatigue induced by challenge and mediatiors 1)no of connective tissue features in hypermobility diagnostic criteria endorsed by participant; 2)baseline inflammatory markers.

Results

ESR and CRP were significantly higher in patients rather than controls, even after correcting for BMI, age and sex (B=5.15, t=2.05, p=0.044; B=1.77, t=2.15, p=0.044 respectively). Adjusted ESR and CRP correlated with both subjective fatigue (B=0.44, t=2.09, p=0.04; B=1.63, t=2.60, p=0.011) and pain severity (B=0.13, t=2.51, p=0.014; B=0.45, t=3.01, p=0.004) at baseline. Autonomic challenge amplified pain (B=14.20, t=2.87, p=0.005) and fatigue (B=31.48, t=5.95, p=<0.001) in patients to a significantly greater degree than controls, controlling for baseline levels. Baseline ESR and CRP also predicted challenge-induced increase in fatigue (B=0.78, t=370, p=<0.001; B=1.91, t=3.36, p=<0.001) and ESR challenge-induced increases in pain (B=0.46, t=2.35, p=0.021).

Mediation analysis demonstrated that number of connective tissue features expressed in hypermobility criteria mediated the degree to which subjective pain was increased by the autonomic challenge (Bootstraped 95% CI of indirect effect do not cross zero, 0.1572 – 6.8171). ESR mediated the degree to which subjective fatigue was increased by the autonomic challenge (Bootstraped 95% CI of indirect effect do not cross zero,0.7541 – 7.3888).

Conclusion

To our knowledge this is the first study to directly explore autonomic and inflammatory mechanisms of pain and fatigue in a combined population of Fibromyalgia and ME/CFS. This study this adds to the evidence-base of baseline inflammatory abnormalities in fibromyalgia and ME/CFS. It highlights their potential role in predicting symptom severity and their potential mechanistic role in autonomic induced pain and fatigue, suggesting future treatment strategies.

References

[1]Eccles JA, Thompson B, Themelis K, Amato ML, Stocks R, Pound A, et al. Beyond bones: The relevance of variants of connective tissue (hypermobility) to fibromyalgia, ME/CFS and controversies surrounding diagnostic classification: an observational study. Clin Med (Lond). 2021;21(1):53-8.

[2]Eccles JA, Davies KA. The challenges of chronic pain and fatigue. Clin Med (Lond). 2021;21(1):19-27.

[3]Hayes AF. Partial, conditional, and moderated moderated mediation: Quantification, inference, and interpretation. Commun Monogr. 2018;85(1):4-40.

Disclosure of Interests

Jessica Eccles: None declared, Charlotte Thompson: None declared, Beth Thompson: None declared, Marisa Amato: None declared, Kristy Themelis: None declared, Hugo Critchley: None declared, Neil Harrison Grant/research support from: speakers bureau, Kevin Davies: None declared

The role of interoception in the mechanism of pain and fatigue in fibromyalgia and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS)

Introduction

Pain, fatigue and anxiety are common features of fibromyalgia and ME/CFS and significantly impact quality of life. Aetiology is poorly defined but dysfunctional inflammatory, autonomic and interoceptive (sensing of internal bodily signals) processes are implicated.

Objectives

To investigate how altered interoception relates to baseline expression of pain, fatigue and anxiety symptoms in fibromyalgia and ME/CFS and in response to an inflammatory challenge.

Methods

Sixty-five patients with fibromyalgia and/or ME/CFS diagnosis and 26 matched controls underwent baseline assessment: pressure-pain thresholds and self-report questionnaires assessing pain, fatigue and anxiety severity. Participants received injections of typhoid (inflammatory challenge) or saline (placebo) in a randomised, double-blind, crossover design, before completing heartbeat tracking tasks. Three interoception dimensions were examined: subjective sensibility, objective accuracy and metacognitive awareness. Interoceptive trait prediction error was calculated as discrepancy between accuracy and sensibility.

Results

Patients with fibromyalgia and ME/CFS had significantly higher interoceptive sensibility and trait prediction error, despite no differences in interoceptive accuracy. Interoceptive sensibility and trait prediction error correlated with all self-report pain, fatigue and anxiety measures, and with lower pain thresholds. Anxiety mediated the positive-predictive relationships between pain (Visual Analogue Scale and Widespread Pain Index), fatigue impact and interoceptive sensibility. After inflammatory challenge, metacognitive awareness correlated with baseline self-reported symptom measures and lower pain thresholds.

Conclusions

This is the first study investigating interoceptive dimensions in patients with fibromyalgia and ME/CFS, which were found to be dysregulated and differentially influenced by inflammatory mechanisms. Interoceptive processes may represent a new potential target for diagnostic and therapeutic investigation in these poorly understood conditions.

Disclosure

No significant relationships.

The effect of COVID-19 on general anaesthesia rates for caesarean section. A cross-sectional analysis of six hospitals in the north-west of England

At the onset of the global pandemic of COVID-19 (SARS-CoV-2), guidelines recommended using regional anaesthesia for caesarean section in preference to general anaesthesia. National figures from the UK suggest that 8.75% of over 170,000 caesarean sections are performed under general anaesthetic. We explored whether general anaesthesia rates for caesarean section changed during the peak of the pandemic across six maternity units in the north-west of England. We analysed anaesthetic information for 2480 caesarean sections across six maternity units from 1 April to 1 July 2020 (during the pandemic) and compared this information with data from 2555 caesarean sections performed at the same hospitals over a similar period in 2019. Primary outcome was change in general anaesthesia rate for caesarean section. Secondary outcomes included overall caesarean section rates, obstetric indications for caesarean section and regional to general anaesthesia conversion rates. A significant reduction (7.7 to 3.7%, p < 0.0001) in general anaesthetic rates, risk ratio (95%CI) 0.50 (0.39-0.93), was noted across hospitals during the pandemic. Regional to general anaesthesia conversion rates reduced (1.7 to 0.8%, p = 0.012), risk ratio (95%CI) 0.50 (0.29-0.86). Obstetric indications for caesarean sections did not change (p = 0.17) while the overall caesarean section rate increased (28.3 to 29.7%), risk ratio (95%CI) 1.02 (1.00-1.04), p = 0.052. Our analysis shows that general anaesthesia rates for caesarean section declined during the peak of the pandemic. Anaesthetic decision-making, recommendations from anaesthetic guidelines and presence of an on-site anaesthetic consultant in the delivery suite seem to be the key factors that influenced this decline.

AB0949 AUTONOMIC AND INFLAMMATORY MECHANISMS OF PAIN AND FATIGUE IN FIBROMYALGIA AND ME/CFS: AN INTERVENTIONAL STUDY

Background:

Fibromyalgia and ME/CFS are complex disorders with overlapping symptoms; the pathoaetiology and clinical distinction are debated, however inflammatory and autonomic abnormalities are observed.

Objectives:

To investigate the role of inflammatory and autonomic nervous system responses in mechanisms of pain and fatigue in fibromyalgia and ME/CFS

Methods:

63 patient participants with clinical diagnoses of fibromyalgia and/or ME/CFS were recruited into a multi-stage interventional study (ISRCTN78820481) alongside 24 healthy controls. All underwent research diagnostic criteria evaluation. The majority underwent autonomic challenge (60 degree head up tilt) and/or inflammatory challenge (placebo-controlled typhoid vaccination) with baseline characterisation of symptoms, inflammatory markers and pre-post measures of pain and fatigue.

Results:

Of the 63 patients, 32% of patients had received a clinical diagnosis of Fibromyalgia; 38% ME/CFS and 30% dual diagnoses. Following research evaluation 89% met ACR diagnostic criteria for fibromyalgia; 94% Canadian Criteria for ME/CFS; 97% Fukada Criteria for ME/CFS

There was a significantly higher ESR in patients compared to controls (p= 0.036). There was a trend towards higher CRP in patients compared to controls (p= 0.076).

ESR correlated with baseline pain score (r=0.309, p=0.011), fatigue severity (r=0.262, p=0.032), fatigue impact (r=0.382, p=0.014) change in fatigue score induced by tilt (r=0.319, p=0.011) and change in pain score induced by placebo-controlled inflammation (r=-0.279, p=0.043). Similarly CRP level correlated with baseline pain score (r=0.340, p=0.005), fatigue impact (r=0.439, p=0.004), change in fatigue (r=-0.277, p=0.045) and pain score (r=-0.394, p=0.014) induced by placebo-controlled inflammation and change in pressure pain theshold induced by tilt (r=0.286, p=0.027).

Baseline IL6 was higher in patients than controls (p = 0.002), correlating with baseline pain score (r = 0.345, p = 0.002) and change in pain score induced by tilt (r=0.281, p=0.21). Change in IL6 induced by inflammatory challenge correlated with inflammation induced fatigue score (r = 0.378, p = 0.01).

Conclusion:

Inflammatory and autonomic mechanisms contribute to pain and fatigue in this frequently overlooked patient group, highlighting possibilities for targeted treatments. Such data will be enriched going forward by neuroimaging and transcriptomic insights.

References:

n/a

Acknowledgments:

This work was supported by Versus Arthritis, Action for Me, Fibroduck Foundation and NIHR

Disclosure of Interests:

Jessica Eccles: None declared, Marisa Amato: None declared, Charlotte Thompson: None declared, Kristy Themelis: None declared, Hugo Critchley: None declared, Neil Harrison Grant/research support from: Yes, Speakers bureau: Yes, Kevin Davies: None declared

Joint Hypermobility Syndrome and Anxiety Disorder: Structural Brain Correlates

Introduction

Joint hypermobility syndrome/Ehlers Danlos III (JHS/EDS III) is a common, connective tissue condition. This group is over-represented in panic/anxiety disorders and exhibits autonomic abnormalities and heightened interoceptive sensibility. Previous neuroimaging in healthy volunteers with hypermobility has observed differences in key emotional brain regions, notably amygdala and insula.

Aims and objective To explore, in a clinical population, the structural brain correlates underpinning the association between JHS/EDS III and anxiety.

Method

Seventy participants were divided into four experimental groups: (2 × 2 factor design: presence/absence of hypermobility; presence/absence of anxiety). Hypermobility was assessed using Brighton Criteria. All participants underwent brief tests of autonomic function and interoception. Structural images were obtained using a 1.5 T MRI scanner. Results are reported at whole brain uncorrected significance threshold of P < 0.001.

Results

Comparison of grey matter volume revealed increased insular volume in anxious patients with JHS/EDS-III compared to anxious patients without (Fig. 1A, B), correlating with initial peak heart rate on standing. Additionally, amygdala volume correlated with hypermobility score in anxious patients, but not in non-anxious individuals (Fig. 1C, D). Amygdala volume correlated with interoceptive accuracy.

Conclusions

This data implicates amygdala and insula as likely neural substrates mediating clinical relationships between hypermobility syndrome and anxiety, demonstrating the relevance of autonomic and interoceptive influences on this relationship. Further work hopes to explore functional and structural connectivity between these regions in JHS/EDS-III.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Charged amino acids as spectroscopic determinants for chlorophyll in vivo

In this paper we propose that the large spectroscopic red shifts observed for chlorophyll (Chl) and bacteriochlorophyll (BChl) in vivo may be due to charged amino acids in the binding site. Molecular orbital calculations of the transition energies of Chl in the field of external charges are carried out. The calculated wavelength shifts induced by these charges are comparable in magnitude to those observed in vivo. Moreover the size of the shifts increases in the order BChl b > BChl a > Chl a, which is the observed trend. The ability of the calculations to account for both the absolute and relative magnitudes of the wavelength shifts argues for the validity of the model. Further indirect support comes from the recent demonstration that charged amino acids are responsible for the colors of visual pigments and bacteriorhodopsin. In addition to their effects on spectra the presence of external charges induces large changes in the ionization potential of Chl molecules and thus might explain the in vivo alteration of the oxidation potentials in reaction centers.

Best interests, dementia and the Mental Capacity Act (2005)

The Mental Capacity Act (2005) is an impressive piece of legislation that deserves serious ethical attention, but much of the commentary on the Act has focussed on its legal and practical implications rather than the underlying ethical concepts. This paper examines the approach that the Act takes to best interests. The Act does not provide an account of the underlying concept of best interests. Instead it lists factors that must be considered in determining best interests, and the Code of Practice to the Act states that this list is incomplete. This paper argues that this general approach is correct, contrary to some accounts of best interests. The checklist includes items that are unhelpful. Furthermore, neither the Act nor its Code of Practice provides sufficient guidance to carers faced with difficult decisions concerning best interests. This paper suggests ways in which the checklist can be developed and discusses cases that could be used in an updated Code of Practice.

Wilder Graves Penfield, 26 January 1891--5 April 1976

The death of Wilder Penfield on 5 April 1976, at the age of 85, marked the end of an era for Canadian neurology and, in many ways, for world neurology. During his long and active career, he had represented a direct link with some of the great medical and neurological figures of the earlier part of the century such as Osier, Sherrington, Holmes and Cajal, and with surgical leaders that included Horsley, Sargent, Leriche, Halsted, Whipple, Cushing and Dandy. Penfield can be called the founder of Canadian neurology. And in a broader sense he can be credited with the development of physiological neurosurgery. He brought to the operating room the meticulous techniques of Sherrington and the stimulation methods of Foerster, combining these with his expert knowledge of the cytology of nervous tissue and the tumours and scars that affect it. The founding in 1934 of the Montreal Neurological Institute, with its then almost unique combination of well planned hospital facilities integrated with scientific laboratories, became his major contribution to neurology at large. His work on cerebral localization and epilepsy assured his scientific distinction. At the time of his retirement in 1960 from surgical practice and from the directorship of the Institute, he was regarded throughout the medical world as one of the outstanding leaders in neurology and neurosurgery.

Do self-fulfilling prophecies accumulate, dissipate, or remain stable over time?

The authors examined whether self-fulfilling prophecies accumulate, dissipate, or remain stable over time by using data from more than 500 6th- through 12th-grade students in public school math classes. The authors used multiple regression analyses to assess the extent to which teacher perceptions predicted students' final math marks and standardized math-test scores from 6th through 12th grade. Control variables included 5 measures of student motivation and 2 measures of previous achievement. The results were consistent with both the dissipation and stability hypotheses. Implications for understanding the extent to which social perception creates social reality and the role of expectations in social problems are discussed.

Do self-fulfilling prophecies accumulate, dissipate, or remain stable over time?

The authors examined whether self-fulfilling prophecies accumulate, dissipate, or remain stable over time by using data from more than 500 6th- through 12th-grade students in public school math classes. The authors used multiple regression analyses to assess the extent to which teacher perceptions predicted students' final math marks and standardized math-test scores from 6th through 12th grade. Control variables included 5 measures of student motivation and 2 measures of previous achievement. The results were consistent with both the dissipation and stability hypotheses. Implications for understanding the extent to which social perception creates social reality and the role of expectations in social problems are discussed.

In search of the powerful self-fulfilling prophecy

This research examined moderators of naturally occurring self-fulfilling prophecies. The authors assessed whether positive or negative self-fulfilling prophecies were more powerful and whether some targets were more susceptible to self-fulfilling prophecies because of their self-concepts in a particular achievement domain and previous academic records. Participants were 98 teachers and 1,539 students in sixth-grade public school math classes. Results yielded a strong pattern showing that teacher perceptions predicted achievement more strongly for low achievers than for high achievers. Results also yielded a much weaker pattern showing that teacher overestimates predicted achievement more strongly than teacher underestimates. Implications for social perceptual accuracy, self-enhancement theory, and understanding when self-fulfilling prophecies are stronger are discussed.

Age and gender differences in children's self- and task perceptions during elementary school

We examined the development of children's self- and task perceptions during the elementary school years. 865 first-, second,- and fourth-grade children (ages 7-10) completed questionnaires assessing their perceptions of competence in, and valuing of, activities in several activity domains (math, reading, sports, and instrumental music). Factor analyses showed that even the first graders had differentiated self-beliefs for the various activities. These analyses also indicated that children's competence beliefs and subjective task values formed distinct factors. Analyses assessing age and gender differences in children's beliefs showed that for all the activities except sports, younger children's (particularly the first graders) perceptions of competence and subjective task values were more positive than the beliefs of the older children. Boys had more positive competence beliefs and values than did girls for sport activities, and more positive competence beliefs for mathematics. Girls had more positive competence beliefs and values than did boys for reading and music activities.

The application of SSADM to modelling the logical structure of proteins

A logical design that describes the overall structure of proteins, together with a more detailed design describing secondary and some supersecondary structures, has been constructed using the computer-aided software engineering (CASE) tool, Auto-mate. Auto-mate embodies the philosophy of the Structured Systems Analysis and Design Method (SSADM) which enables the logical design of computer systems. Our design will facilitate the building of large information systems, such as databases and knowledgebases in the field of protein structure, by the derivation of system requirements from our logical model prior to producing the final physical system. In addition, the study has highlighted the ease of employing SSADM as a formalism in which to conduct the transferral of concepts from an expert into a design for a knowledge-based system that can be implemented on a computer (the knowledge-engineering exercise). It has been demonstrated how SSADM techniques may be extended for the purpose of modelling the constituent Prolog rules. This facilitates the integration of the logical system design model with the derived knowledge-based system.

A unitary hypothesis of mind-brain interaction in the cerebral cortex

A brief introduction to the brain-mind problem leads on to a survey of the neuronal structure of the cerebral cortex. It is proposed that the basic receptive units are the bundles or clusters of apical dendrites of the pyramidal cells of laminae V and III-II as described by Fleischhauer and Peters and their associates. There are up to 100 apical dendrites in these receptive units, named dendrons. Each dendron would have an input of up to 100,000 spine synapses. There are about 40 million dendrons in the human cerebral cortex. A study of the influence of mental events on the brain leads to the hypothesis that all mental events, the whole of the World 2 of Popper, are composed of mental units, each carrying its own characteristic mental experience. It is further proposed that each mental unit, named psychon, is uniquely linked to a dendron. So the mind-brain problem reduces to the interaction between a dendron and its psychon for all the 40 million linked units. In my 1986 paper (Proc. R. Soc. Lond. B 227, 411-428) on the mind-brain problem, there was developed the concept that the operation of the synaptic microsites involved displacement of particles so small that they were within range of the uncertainty principle of Heisenberg. The psychon-dendron interaction provides a much improved basis for effective selection by a process analogous to a quantal probability field. In the fully developed hypothesis psychons act on dendrons in the whole world of conscious experiences and dendrons act on psychons in all perceptions and memories. It is shown how these interactions involve no violation of the conservation laws. There are great potentialities of these unitary concepts, for example as an explanation of the global nature of a visual experience from moment to moment. It would seem that there can be psychons not linked to dendrons, but only to other psychons, creating what we may call a psychon world.

The pattern of childhood hepatitis B infection in two Gambian villages

Serologic markers of hepatitis B virus (HBV) infection were measured in children from Manduar and Keneba, two adjacent villages in The Gambia, in 1980 and in 1984. The rate of HBV infection over the 4 years differed markedly: in Manduar 71% of children who were less than 5 years of age in 1980 became infected, whereas in Keneba only 37% became infected. Male children were more frequent carriers of either HBs or e antigen than were female children. Marked clustering of hepatitis B surface antigen (HBsAg) antigenemia within sibling relationships was shown in both villages. The chance of the youngest child in a household being a carrier of HBsAg was strongly related to the number of antigen-positive siblings. Four years later, 53% of children who were initially positive for HBsAg and 33% who were positive for hepatitis B e antigen still carried these antigens. Jaundice was not observed.

A theoretical analysis of the effects of sonication on differential absorption flattening in suspensions of membrane sheets

A theoretical analysis is presented for the flattening of absorption and circular dichroic spectra of suspensions of membrane sheets containing proteins. Equations are presented to describe the dependence of this artifact on the size of the sheets. Values for the flattening coefficients QA and QB are calculated both as a function of absorptivity and sheet size. These studies show that sonication in an inadequate procedure for eliminating flattening in these samples.

The anionic permeability of the inhibitory postsynaptic membrane of hippocampal pyramidal cells

The anion permeability and current sensitivity of inhibitory postsynaptic potentials (i. p. s. ps) of CA1 hippocampal pyramidal cells have been studied with intracellular recording techniques. Passage of depolarizing current through the microelectrode increased the size of i. p. s. ps while hyperpolarizing current decreased and eventually reversed the i. p. s. ps. The early portion of the i. p. s. p. was most sensitive to current. The results obtained from the injection of anions into the pyramidal cells indicated that a sharp dichotomy existed: either the anion was permeable as shown by a depolarizing shift in the i. p. s. p., or the anion was imper­ meable, there being as a consequence a hyperpolarizing shift in the i. p. s. p. The permeable anions include Br¯ , NO¯ 2 , NO¯ 3 , SCN¯, OCN¯, CIO¯ 3 and HCO¯ 2 , while the impermeable anions included citrate, glutamate, sulphate, methylsulphate, bromate, chromate, acetate and fluoride. These results are identical to those obtained by ion injection into motoneurons. Diffusion of anions into pyramidal cells supported the results from ion injection; namely, that there was a sharp dichotomy between permeant and impermeant anions. However, acetate, and to a lesser extent bromate and glutamate, were exceptions, since these anions led to an abolition or reduction of the hyperpolarizing i. p. s. p. and yet from ion injection studies these anions were clearly impermeant. Possible explanations for this paradox are given in the following paper. The present findings suggest that the anion permeability of the inhibitory postsynaptic membrane in hippocampal pyramidal cells is similar to that reported for spinal motoneurons.

The ionic mechanisms concerned in generating the i.p.s.ps of hippocampal pyramidal cells

A variety of experimental tests has been initiated in order to discover whether the large hyperpolarizing inhibitory postsynaptic potentials (i. p. s. ps) of hippocampal pyramidal cells are generated by the influx of Cl¯ down a gradient maintained by an outward pumping of Cl¯ across the membrane, as has been proposed by Lux, Llinás and associates for other i. p. s. ps. Intravenous infusion of NH 4 acetate or intracellular NH 4 acetate caused little depression of extracellular field potentials and of i. p. s. ps recorded intracellularly, i. e. there was no evidence for the blockade of an outwardly directed chloride pump. The recovery time constants in seconds from an increase in intracellular chloride, either by chloride injections (22.7 ± 6.9) or by passage of depolarizing current through K + salt-filled microelectrodes (20.6 + 6.8) did not differ from the time constant of recovery from depleted intracellular chloride by passage of hyperpolarizing current through electrodes containing K + salts of impermeant anions (21.1 + 5.4). Depletion of the intracellular K + concentration following sodium injections caused a long-lasting depolarizing shift in the i. p. s. p. with a recovery time constant of almost 70 s. These results are identical with those obtained in spinal moto­neurons, where the very slow recovery was explained by an inward KCl pump triggered by low internal K + . Our results suggest that an outward Cl¯ pump dependent on internal Cl¯ concentration does not exist in hippocampal neurons or at least on their somatic membrane. Two alternative hypotheses are given to account for our negative findings with respect to NH 4 acetate action on the hyperpolarizing i. p. s. ps and on the rate of Cl¯ movements across the membrane. First, the original hypothesis as proposed by Eccles and collaborators, in which conductance increases to both Cl¯ and K + ions produce the hyperpolarizing i. p. s. ps of hippocampal neurons. However, we have no positive evidence for the involvement of K + ions. Secondly, an outward Cl¯ pump keeps the E Cl more negative than the resting potential and the i. p. s. p. is solely caused by Cl¯ as postulated by Lux, Llinás and associates. This pump is located remotely in the dendrites and is resistant to the action of NH 4 acetate. This pump would have to be effective in a background manner so that it did not interfere appreciably with the diffusional exchange of Cl¯ ions across the soma membrane.

From electrical to chemical transmission in the central nervous system

I was very attracted by the title that Dr Iversen thought up for me. I have recalled many memories of the 1930’s in my efforts to recover the story of the Chemical-Electrical controversy that has apparently become legendary! But like all legends it needs checking by a little archival research; it was salutary to find that even my own memory was at fault! I have to be wary because there are present here many of those concerned in those memorable disputations, notably of course Wilhelm Feldberg, but also Marthe Vogt, Ulf von Euler, H. O. Schild, Hank Macintosh, and of course our chairman Z. M. Bacq. Naturally on this occasion I want to concentrate on the story as Dale told it in his many lectures.

Letters from C. S. Sherrington, F.R.S., to Angelo Ruffini between 1896 and 1903

Through the great kindness of Professor Guiseppe Moruzzi I learned of the valuable collection of Sherrington’s letters that were in the possession of Professor Gastone Lambertini, who was a distinguished pupil of Professor Ruffini’s. Professor Lambertini has generously provided me with copies of sixteen letters of Sherrington’s from 1896-1903. These letters are of remarkable interest because they tell a wonderful story of the scientific associations between investigators in different countries. They provide a valuable documentation of the true spirit of science as it was practised around the turn of the century. I am indebted to Professor Lambertini for preparing specially for this publication a brief biographical sketch of Professor Angelo Ruffini which now follows.