AB0589 TOCILIZUMAB FOR GIANT CELL ARTERITIS: BASELINE AND TWELVE MONTH AUDIT DATA FROM THE UK BRISTOL AND BATH MULTIDISCIPLINARY MEETING

Background

Giant Cell Arteritis (GCA) is a systemic vasculitis involving large and medium-sized blood vessels. Treatment is with high dose glucocorticoids. Steroid-sparing agents and Tocilizumab (TCZ) are used for refractory or relapsing cases. NHS England requires all GCA patients to be discussed in a regional multidisciplinary team meeting (MDT) prior to commencing TCZ. TCZ has only been permitted for a maximum of one year; this time limitation was extended during the Covid-19 pandemic (1). The monthly virtual Bristol and Bath regional MDT started in November 2018.

Objectives

We aimed to review: 1) Baseline data on all patients referred to the Bristol and Bath TCZ for GCA MDT, including demographics, clinical presentation and previous steroid-sparing agents used and 2) 12 month follow up data including number of completions, adverse effects, and flares on treatment.

Methods

The TCZ MDT referral proforma, adapted from the NHS England Blueteq approval form, was reviewed for all patients referred. 12 month follow up data was obtained from clinic letters.

Results

Baseline data

Thirty-eight cases were referred between November 2018 and September 2021. Of these, 31 were approved for TCZ usage; 100% fulfilled the criteria for either refractory (n=11) or relapsing (n=20) disease. Mean age was 74 years and 74.2% were female. Average disease duration was 161.5 days for the refractory and 827.3 days for the relapsing group.

77.4% had cranial GCA, 48.4% had large vessel involvement, 45.2% had visual symptoms and 25.8% had ischaemic visual loss. The positive investigations were PET-CT (48.4%), temporal artery ultrasound (41.9%) and temporal artery biopsy (32.3%).

64.5% had trialled a steroid-sparing agent at time of referral (61.3 % methotrexate, 9.7% azathioprine, 6.5% leflunomide), 35.5% had received intravenous methylprednisolone and 58% were receiving greater than 40mg prednisolone at the time of referral.

Glucocorticoid adverse effects of osteoporosis, weight gain, cataracts and hypertension were each seen in 19.4%; whilst diabetes, neuropsychiatric symptoms and sleep disturbance were each reported in 16.1%.

Those with ocular involvement tended to be referred earlier than those without (478.2 days vs 648.1 days), were referred on higher doses of glucocorticoids (71.4% vs 47.1% on ≥ 40mg) and had less steroid-sparing agents prior to referral.

Follow up data

In December 2021, a follow-up audit revealed 14/31 patients had completed at least 12 months of tocilizumab; 5 of these had had an extension under Covid-19 exceptional guidance (mean duration of 5.2 months). Of the remaining 17: 3 patients had stopped early (1 death, 1 moved away, 1 due to adverse effects of headache and gastro-intestinal side effects), 4 had not started tocilizumab and 10 had not completed 12 months of treatment at that point.

Adverse events in the 14 patients at 12 months included: liver abnormalities (2/14; 14.3%), neutropenia (2/14; 14.3%), thrombocytopaenia (1/14; 7.1%), soft tissue infections (3/14; 21.4%), urinary tract infection (1/14; 7.1%) and lipid derangement (4/14 28.6%). One case of GCA relapse occurred on TCZ (mild headache and raised inflammatory markers settled on small increase in prednisolone). After 12 months, mean prednisolone dose was 3mg (range 0-15mg).

Conclusion

All patients approved for Tocilizumab in the GCA MDT fulfilled NHS England criteria for either relapsing or refractory disease. The majority of cases had cranial disease, but almost half had either ocular or large vessel involvement, reflecting a severe spectrum of disease. Cases showed a high burden of glucocorticoid toxicity. Follow up data suggests that TCZ was effective in allowing glucocorticoid weaning and disease control, but with some adverse effects. Future work to follow up patients after stopping Tocilizumab would be informative, as the twelve month limitation on treatment is likely to be re-instated.

References

[1]https://www.england.nhs.uk/coronavirus/publication/tocilizumab-for-giant-cell-arteritis-gca-during-the-covid-19-pandemic-rps-2007/

Disclosure of Interests

Chandrin N. R. Jayatilleke: None declared, Aishwarya Anilkumar: None declared, Shalini Janagan: None declared, Robert W Marshall: None declared, Sarah Skeoch: None declared, Catherine Guly Grant/research support from: Eli Lilly and Company - paid consultant for a research trial, Fang En Sin: None declared, Keziah Austin: None declared, Laith Al-Sweedan: None declared, Alexandra Bourn: None declared, Lynsey Clarke: None declared, Harsha Gunawardena: None declared, Baashar Boyce: None declared, Sally Knights: None declared, John D Pauling: None declared, Elizabeth Reilly: None declared, Timothy D Reynolds: None declared, Sarah Villar: None declared, Joanna C Robson: None declared

Gemella haemolysans spondylodiscitis: a report of two cases

We report on two cases of infective spondylodiscitis caused by Gemella haemolysans in otherwise healthy patients. This organism has only rarely been identified as a cause of bone and joint infection, with only two previous reports of infective spondylodiscitis. We describe the clinical features, investigations and treatment options.

Cerebral venous sinus thrombosis following cervical disc arthroplasty

Cerebral venous sinus thrombosis is a rare condition, which is difficult to diagnose. It has not previously been reported following surgery to the cervical spine . We report such a case in a 45-year-old man after cervical disc replacement. A high index of suspicion, with early imaging of the brain and prompt treatment, can produce a favourable outcome, albeit not in this case.

Conservatively treated massive prolapsed discs: a 7-year follow-up

INTRODUCTION

The natural history of a lumbar hernia of the nucleus pulposus (HNP) is not fully known and clear indications for operative intervention cannot be established from the literature. Several studies have shown that the largest discs appear to have the greatest tendency to resolve. The aim of this study was to investigate whether massive prolapsed discs can be safely managed conservatively once clinical improvement has occurred.

PATIENTS AND METHODS

Thirty-seven patients were studied by clinical assessments and serial magnetic resonance imaging (MRI) over 2 years. Patients had severe sciatica at first, but began to show clinical improvement despite the large disc herniations. Clinical assessment included the Lasegue test and neurological appraisal. The Oswestry Disability Index was used to measure function and changes in function. Serial MRI studies allowed measurement of volume changes of the herniated disc material over a period of time.

RESULTS

Initial follow-up at an average of 23.2 months revealed that 83% had a complete and sustained recovery at the initial follow-up. Only four patients required a discectomy. The average Oswestry disability index improved from 58% to 15%. Volumetric analysis of serial MRI scans found an average reduction of 64% in disc size. There was a poor correlation between clinical improvement and the extent of disc resolution.

CONCLUSIONS

A massive disc herniation can pursue a favourable clinical course. If early progress is shown, the long-term prognosis is very good and even massive disc herniations can be treated conservatively.

The functional relevance of neurological recovery 20 years or more after lumbar discectomy

The indications for lumbar discectomy are pain and neurological dysfunction. This paper considers the extent and timing of neurological recovery following spinal decompression.

Nicotine enemas for treatment of ulcerative colitis: a study of the pharmacokinetics and adverse events associated with three doses of nicotine

BACKGROUND

Transdermal nicotine is of value in active ulcerative colitis but causes adverse events because of systemic absorption. Nicotine enemas may give rise to fewer adverse events.

AIM

To assess the pharmacokinetics of nicotine enemas in three doses.

METHODS

Thirteen volunteers, all non-smokers but three ex-smokers, were given enemas on separate occasions containing 3, 6 and 9 mg of nicotine, in ascending dose order. Adverse events were recorded and blood samples taken over 8 h for measurement of serum nicotine and cotinine.

RESULTS

Enemas were retained by most subjects. Eleven of 14 adverse events were 'early'--30-105 min after the enema, corresponding to maximum plasma nicotine concentrations; three events were later, 4-8 h after the enema and unrelated to the tmax. 'Early' adverse events occurred in eight subjects--six with 9 mg. The three highest plasma nicotine concentrations were with 9 mg and associated with headache, nausea and sweating. Only one had adverse events with 3 mg and withdrew from the study. Nicotine Cmax with 6 and 9 mg doses were respectively two and three times the value with 3 mg. Peak nicotine concentrations occurred 44-50 min after the enema.

CONCLUSION

The 6 mg dose of nicotine probably represents the dose to use in clinical practice - for the highest therapeutic dose with a low risk of adverse events.

Differential effect of nitric oxide synthase inhibition on sigmoid colon longitudinal and circular muscle responses to nicotine and nerve stimulation in vitro

BACKGROUND

Nicotine has been shown to release nitric oxide from nerves in human sigmoid colon. This effect has been used to investigate the innervation and functional relationship of the longitudinal and circular muscle layers.

METHODS

Strips of longitudinal and circular muscle were obtained from 19 patients with colorectal cancer. The strips from ten patients were subjected to electrical field stimulation (EFS) in vitro using stimulus parameters for selective stimulation of nerves. The effect of nicotine 1-10 micromol/l on EFS responses was then measured in the presence and absence of a nitric oxide synthase inhibitor, nitro-L-arginine methyl ester (L-NAME) 200 micromol/l. The effect of nicotine on spontaneous activity was investigated in the muscle strips from the other nine patients.

RESULTS

Both longitudinal and circular strips responded to EFS with contraction. The time to achieve a peak contractile response (time to peak; TTP) was significantly longer (P<0.001) in circular strips. L-NAME reduced the mean(s.e.m.) TTP in circular muscle from 23.3(2.0) to 17.2(1.5) s (P=0.007) and altered its pattern of response to resemble that of longitudinal muscle. Nicotine 10 micromol/l reduced the contraction to EFS in circular (P<0.001) but not in longitudinal (P=0.347) muscle. The nicotine-induced reduction in circular muscle contraction was blocked by L-NAME 200 micromol/l (P=0.005).

CONCLUSION

These findings suggest that nitric oxide release on neural stimulation is greater in circular than in longitudinal muscle.

Survival analysis is a better estimate of recurrent disc herniation

Studies on recurrent disc herniation quote rates of recurrence without regard to the times of recurrence and the influence of longer follow-up. Our objective was to assess the use of survival analysis to measure the rate of revision after lumbar microdiscectomy. We undertook a retrospective analysis of the hospital records of 993 patients who underwent lumbar microdiscectomy over a period of ten years. After calculating the overall rate of revision for the mean length of follow-up, we carried out a survival analysis using the life-table method. During the study period 49 patients had a revision microdiscectomy. This gave an overall rate of revision of 4.9% at a mean follow-up of 5.25 years. Using survival analysis, the rate of revision was 7.9% at a follow-up of ten years when the number at risk was 84. Survival analysis gives a more accurate estimation of the true rate of recurrence for patients undergoing lumbar microdiscectomy. The method allows better comparison between different interventions for disc herniation.

Treatment of cutaneous calcinosis in limited systemic sclerosis with minocycline

OBJECTIVES

To evaluate the effect of minocycline as treatment for cutaneous calcinosis in limited cutaneous systemic sclerosis (lcSSc).

METHODS

Patients with lcSSc who had cutaneous calcinosis causing pain or ulceration, or both, were prescribed minocycline 50 or 100 mg daily regularly in an open label manner between November 1994 and April 2000. At routine clinical follow up the appearance of the calcinosis deposits was assessed clinically and radiographically, and the patients' assessment of the degree of discomfort, size, and frequency of ulceration was recorded. Demographic data, including disease duration, clinical features, and antinuclear antibody (ANA) titres, were also recorded.

RESULTS

Nine patients have been treated to date. Eight of the nine patients were ANA positive, five of whom were positive for anticentromere antibodies. Eight patients have shown definite improvement and seven patients continue to receive treatment. The frequency of ulceration and inflammation associated with the calcinosis deposits decreased with treatment. The size of the calcinosis deposits also decreased but was less dramatic than expected. Improvement occurred at the earliest after one month of treatment with a mean (SD) of 4.8 (3.8) months. The mean (SD) length of treatment was 3.5 (1.9) years. An unexpected effect was the darkening of the calcinosis deposits to a blue/black colour.

CONCLUSIONS

Minocycline may be effective in the control of calcinosis in systemic sclerosis. A low dose only is required and appears to be generally well tolerated. The mechanism of action may be mainly through inhibition of matrix metalloproteinases and anti-inflammatory effects. Calcium binding properties and antibacterial actions may also have a role.

Methotrexate in the treatment of ankylosing spondylitis

There have been few well-conducted studies into the efficacy of methotrexate in Ankylosing spondylitis. The results of a new prospective study in 51 patients are presented in this issue but the clinical response was poor. A recurring theme, however, is the promising effect noted on peripheral joints compared with that on the axial skeleton. Recent histological and magnetic resonance imaging evidence suggests that synovitis and subchondral bone marrow changes offer a more rational explanation for widespread joint destruction than does enthesitis alone. Furthermore, enthesis lesions close to synovial joints occur frequently and may be intimately linked with peripheral joint synovitis. At the moment there is no hard evidence of efficacy in axial disease, but these observations raise the possibility that suppression of synovitis might help in the spine, and that enthesitis might respond wherever it is anatomically. Thus further long-term, placebo-controlled studies are needed to address specifically the issues of enthesitis. spinal symptom relief and the suppression of long-term ankylosis.

Nitric oxide mediates a therapeutic effect of nicotine in ulcerative colitis

BACKGROUND

Ulcerative colitis is a condition of nonsmokers in which nicotine is of therapeutic benefit.

AIMS

To examine the in vitro effect of nicotine on colonic smooth muscle activity and the role of nitric oxide (NO) as a mediator.

METHODS

Nicotine, 1-10 microM, was administered to strips of circular muscle from the distal sigmoid colon of 9 patients with active ulcerative colitis and 18 with colorectal cancer. The effect of electrical field stimulation (EFS) was examined before nicotine was added. Finally L-NAME, a NO synthetase inhibitor, was added before nicotine was administered again.

RESULTS

Muscle strips developed similar spontaneous resting tone. In response to EFS, ulcerative colitis tissue developed lower tensions than the controls. Nicotine significantly reduced the resting tone and peak tension after EFS, with a greater effect in controls. With L-NAME, peak tensions were increased more in ulcerative colitis than controls, and nicotine produced a much smaller reduction.

CONCLUSIONS

Nicotine reduces circular muscle activity, predominantly through the release of nitric oxide-this appears to be 'up-regulated' in active ulcerative colitis. These findings may explain some of the therapeutic benefit from nicotine (and smoking) in ulcerative colitis and may account for the colonic motor dysfunction in active disease.

Analysis of the results of the C-Fit uncemented total hip arthroplasty in young patients with hydroxyapatite or porous coating of components

Young patients at 2 separate centers received a C-Fit uncemented arthroplasty, with randomization to porous or hydroxyapatite coating. No difference in survival could be found between components that were porous or hydroxyapatite coated, with 27.5% being revised within 8 years, mainly for aseptic loosening. Acetabular augmentation screws or offset acetabular liners similarly did not affect outcome. Two of the offset liners had spun within the metal acetabular liners, with early failure. Some of the survivors showed poor clinical scores, but there was no correlation between clinical score and radiographic evidence of loosening. These results are comparable to the poorest reported survival figures in the literature for uncemented prostheses. Prosthesis coating could not be shown to affect component survival for this prosthesis.

Absence of interaction between tiagabine, a new antiepileptic drug, and the benzodiazepine triazolam

In a randomised, double blind, placebo-controlled, four-period cross-over study in 12 healthy volunteers, the potential pharmacodynamic and pharmacokinetic interactions between the new antiepileptic drug, tiagabine, and the benzodiazepine, triazolam, were investigated. A single dose of tiagabine HCl 10 mg did not enhance the sedative or cognitive effects of a single dose of the benzodiazepine triazolam 0.125 mg, although the time-course of the effects was prolonged. Furthermore, tiagabine did not produce any statistically significant effects on the pharmacokinetics of triazolam. Similarly, the pharmacokinetics of tiagabine were not modified by triazolam. Tiagabine was well tolerated when administered alone or with triazolam.

Transoral fusion with internal fixation in a displaced hangman's fracture

STUDY DESIGN

A case is reported in which late displacement of a "hangman's fracture" was managed by transoral C2-C3 fusion by using bicortical iliac crest graft and a titanium cervical locking plate.

OBJECTIVES

To review the management of unstable fractures of the axis and to study other reports of transoral instrumentation of the cervical spine.

SUMMARY OF BACKGROUND DATA

Undisplaced fractures of the axis are considered to be stable injuries. Although late displacement is unusual, it can lead to fracture nonunion with persisting instability and spinal cord dysfunction. In this situation, an anterior fusion of the second and third cervical vertebrae is preferred to a posterior fusion from the atlas to the third cervical vertebra, which would abolish lateral rotation between C1 and C2.

METHODS

The literature on hangman's fractures was reviewed. Clinical and radiographic details of a case of C2 instability were recorded, and the particular problems posed by late displacement were considered.

RESULTS

There are no other reports of transoral instrumentation of the cervical spine. A sound fusion of C2-C3 was obtained without infection or other complications. Good neck movement returned by 6 months after surgery.

CONCLUSION

Undisplaced fractures of the axis are not always stable. The transoral route allows good access for stabilization of displaced hangman's fractures. In special circumstances, a locking plate may prove useful in securing the bone graft. The cervical spine locking plate can be inserted transorally with no complications and by using standard instrumentation.

FAR LATERAL LUMBAR DISC HERNIATION

Of a total of 330 patients requiring operation on a lumbar disc, 20 (6.1%) with lateral disc prolapse had a new muscle-splitting, intertransverse approach which requires minimal resection of bone.

There were 16 men and 4 women with a mean age of 52 years. All had intense radicular pain, 15 had femoral radiculopathy and 19 a neurological deficit. Far lateral herniation of the disc had been confirmed by MRI.

At operation, excellent access was obtained to the spinal nerve, dorsal root ganglion and the disc prolapse. The posterior primary ramus was useful in locating the spinal nerve and dorsal root ganglion during dissection of the intertransverse space.

At review from six months to four years, 12 patients had excellent results with no residual pain and six had good results with mild discomfort and no functional impairment. Two had poor results. There had been neurological improvement in 17 of the 20 patients.

We report a cadaver study of the anatomy of the posterior primary ramus. It is readily identifiable through this approach and can be traced down to the spinal nerve in the intertransverse space.

We recommend the use of a muscle-splitting intertransverse approach to far lateral herniation of the disc, using the posterior primary ramus as the key to safe dissection.

Far lateral lumbar disc herniation. The key to the intertransverse approach

Of a total of 330 patients requiring operation on a lumbar disc, 20 (6.1%) with lateral disc prolapse had a new muscle-splitting, intertransverse approach which requires minimal resection of bone. There were 16 men and 4 women with a mean age of 52 years. All had intense radicular pain, 15 had femoral radiculopathy and 19 a neurological deficit. Far lateral herniation of the disc had been confirmed by MRI. At operation, excellent access was obtained to the spinal nerve, dorsal root ganglion and the disc prolapse. The posterior primary ramus was useful in locating the spinal nerve and dorsal root ganglion during dissection of the intertransverse space. At review from six months to four years, 12 patients had excellent results with no residual pain and six had good results with mild discomfort and no functional impairment. Two had poor results. There had been neurological improvement in 17 of the 20 patients. We report a cadaver study of the anatomy of the posterior primary ramus. It is readily identifiable through this approach and can be traced down to the spinal nerve in the intertransverse space. We recommend the use of a muscle-splitting intertransverse approach to far lateral herniation of the disc, using the posterior primary ramus as the key to safe dissection.

The effect of intravenous aminophylline on essential tremor

AIMS

The effects of intravenous aminophylline (375 mg) or placebo (saline) were studied in 10 patients with benign essential tremor.

METHODS

This was a single-blind crossover study. Patients received aminophylline by i.v. infusion over 15 min or saline at least 1 week apart. Tremor was measured by a peizoresistive accelerometer at 15 min intervals predose and up to 2 h. Plasma theophylline concentrations were measured by h.p.l.c.

RESULTS

Tremor power was significantly greater following aminophylline (5.67-6.2 Hz) than placebo (5.6-5.9 Hz).

CONCLUSIONS

We conclude that intravenous aminophylline potentiates benign essential tremor when given acutely by the intravenous route in the doses required to achieve therapeutic benefits in asthma.

The subjective effects of low-dose propofol. A double-blind study to evaluate dimensions of sedation and consciousness with low-dose propofol

In this study the subjective effects (sedation and mood) of subanaesthetic doses of propofol were examined in 28 healthy male volunteers. A computer model was used to predict the infusion profiles necessary to obtain steady state propofol plasma concentrations of 0.3 microgram.ml-1, 0.6 microgram.ml-1, 0.9 microgram.ml-1. Objective measures of sedation from saccadic eye movement and choice reaction time gave significant dose responses at each level but a battery of psychometric tests failed to show dose-related subjective responses. Of particular note in the subjective data is the lack of a difference between groups or even of a consistent trend within the data. This suggests that a low concentration of propofol in plasma does not induce euphoria or a sense of well-being. The anecdotal evidence available for mood changes with propofol therefore remains unsubstantiated.

Effects of small concentrations of isoflurane on some psychometric measurements

We have investigated the effects of 9.5% and 14.1% MAC concentrations of isoflurane on some psychometric measurements. Both concentrations depressed peak saccadic velocity (P < 0.01), choice reaction time (P < 0.05) and visual analogue scores for sedation (P < 0.05), but not the critical flicker fusion threshold. The incidence of errors in saccade tasks increased in a dose-related fashion, which made analysis of peak saccadic velocity less accurate at more than 10% MAC. The percentage error itself was an indicator of the depth of sedation. All the objective measures correlated highly with the estimated brain tension of isoflurane (r2 = 0.86-0.96), but not the visual analogue score for sedation (r2 = 0.51). This suggests that a combination of peak saccadic velocity, percentage error and choice reaction time is a potentially useful batch of tests to measure recovery from anaesthesia.

Effects of zolpidem on saccadic eye movements and psychomotor performance: a double-blind, placebo controlled study in healthy volunteers

1. Peak saccade velocity provides a valuable means of assessing the sedative effect of drugs in humans. The present study investigated the effects of zolpidem, an imidazopyridine hypnotic, on saccade velocity in healthy volunteers after single and repeated administration. 2. Zolpidem 5 mg, 10 mg and 20 mg significantly and dose dependently depressed peak saccade velocity during the 1.5 h after a single administration. On the morning after zolpidem administration, peak saccade velocity had returned towards pretreatment levels. Nitrazepam 10 mg also significantly depressed peak saccade velocity but the effect was maintained the following morning. The saccade response to zolpidem (5 and 10 mg) was undiminished after the seven nightly doses. 3. Nightly administration of zolpidem improved subjective sleep quality and there was no evidence of rebound insomnia following cessation of drug treatment.

Control of the human ileocaecal junction: an in vitro analysis of adrenergic and non-adrenergic non-cholinergic mechanisms

Circular muscle strips from the human ileocaecal junction developed myogenic tone (sustained resting tension) in vitro and showed an obvious component of relaxation in response to electrical field stimulation. These features are considered typical of sphincteric muscle because circular muscle strips from terminal ileum 1-2 cm proximal to the junction and from the caecum or ascending colon 1-2 cm distal to the junction developed little or no tone and showed predominantly contractile responses to electrical-field stimulation. In 18 out of 29 specimens, junctional strips showed excitatory responses to adrenaline or noradrenaline. The relaxation of junctional strips was non-adrenergic non-cholinergic (NANC) in nature. Nitric oxide appears to be involved in the NANC relaxation.

Neurotransmitter feedback is not important in modulating the noradrenergic component of responses of rat vas deferens to twin pulse electrical field stimulation

1. Drug effects on the full time-course of tension responses of the rat vas deferens to challenges of twin pulse field stimulation (TPFS) were examined. A microprocessor-controlled system was used to regulate stimulus delivery, on-line data collection and subsequent data analysis. 2. The second, noradrenergic phase of the response to the second stimulus of TPFS was missing when the interpulse interval was set at 3 s but was progressively restored as the interpulse interval was extended to 120 s. 3. With a 3 s interpulse interval, the missing second phase of the response to the second stimulus was not restored by the selective alpha 2-adrenoceptor antagonists yohimbine, imiloxan or idazoxan, indicative that alpha 2-adrenoceptor-mediated feedback inhibition of noradrenaline release is not the predominant mechanism modulating this response component. 4. Incubation with the P1-purinoceptor antagonist 8-phenyl-theophylline also failed to restore the missing noradrenergic component in the response to the second stimulus of TPFS. 5. Nevertheless, both responses to TPFS were impaired by the selective alpha 2-adrenoceptor agonist clonidine and by the P1-purinoceptor agonist 2-chloroadenosine, indicating the presence of functional presynaptic receptors of both types. These agonist-induced inhibitory effects were readily reversed by those antagonists which had failed to restore the missing noradrenergic component in the second response to TPFS.

Evidence for involvement of nitric oxide in the non-adrenergic non-cholinergic (NANC) relaxation of human lower oesophageal sphincter muscle strips

Electrical field stimulation of circular muscle strips from human lower oesophageal sphincter reveals a predominant relaxation response. This relaxation is non-adrenergic non-cholinergic (NANC). The nitric oxide synthesis-blocking agent N omega-nitro-L-arginine (10-100 microM) reduces or abolishes this NANC relaxation, suggesting involvement of nitric oxide in the response.

Separation of putative alpha 1A- and alpha 1B-adrenoceptor mediated components in the tension response of the rat vas deferens to electrical field stimulation

1. The effects of the putative alpha 1B-adrenoceptor antagonist, chloroethylchlonidine (CEC), on tension responses of the rat isolated whole vas deferens to single and multiple pulses of electrical field stimulation have been evaluated by use of a microcomputer system which enables the averaging of like-responses throughout their time course. 2. CEC (10(-7) to 3 x 10(-6) M) selectively and in a concentration-dependent manner blocked the noradrenergic component of the response to a single field stimulus in the absence or presence of nifedipine (10(-5) M, which blocked the purinergic but not the noradrenergic component of the response). The concentration-response curve of the vas to exogenously-applied noradrenaline (NA) was unaffected by CEC (10(-6) M) but was flattened by nifedipine (10(-5) M). 3. The tension response to 10 Hz trains of pulses was biphasic, with an early (less than 2 s) and a plateau (greater than 4 s) phase. We deduce from our pharmacological analysis that the early phase contains a putative alpha 1B-adrenoceptor component (susceptible to CEC or prazosin but not to nifedipine) and a P2-purinoceptor component (susceptible to suramin or nifedipine) whereas the plateau phase contains an alpha 1A-adrenoceptor component (susceptible to prazosin or nifedipine but not to CEC) and a P2-purinoceptor component (susceptible to suramin or nifedipine). 4. We suggest that the putative alpha 1B-adrenoceptors may be functionally confined to the synaptic region whereas the putative alpha 1A-adrenoceptors are excluded from this region. Trains of pulses would allow NA to accumulate and spill out beyond the synaptic region to reach and activate the putative alphalA-adrenoceptors.

Effects of low concentrations of cyclopropane and halothane on peak velocity of saccadic eye movements

We have investigated the effect of 4.7 and 8.8% MAC of cyclopropane, and 5.3 and 9.3% MAC of halothane on the peak velocity of saccadic eye movements (PSV) in six healthy volunteers. Both concentrations of cyclopropane and halothane significantly depressed PSV (P less than 0.01) compared with air, in a dose-related fashion. Halothane depressed PSV significantly more than cyclopropane (P less than 0.05). PSV returned to baseline within 5 min after discontinuation of the agents. There was no significant difference between cyclopropane, halothane and air in subjective assessment of sedation.

The detection of artefacts in EEG series

In a clinical trial of an anticonvulsant drug, series of electroencephalogram readings are sometimes obtained. These may contain artefacts, that is patches of atypical values which must be identified and either removed or compensated for before a full analysis can be carried out. Methods for identifying such artefacts are discussed. These include non-parametric methods and also parametric ones combining the ideas of autoregressive modelling and of influence in regression. These methods are described and illustrated on typical data sets.

Effect of low concentrations of nitrous oxide and isoflurane on peak velocity of saccadic eye movements

Peak velocity of saccadic eye movements was studied in six healthy volunteers who were each given, on separate days, 5% and 10% MAC of nitrous oxide (5% and 10% end-tidal) or of isoflurane (0.06% and 0.12% end-tidal) or air, each gas for 25 min. Subjective assessment following each treatment was also undertaken. No significant difference was found between air and either 5% or 10% nitrous oxide. However, significant differences occurred at 15 and 25 min after 0.06% isoflurane compared with air (P less than 0.05) and highly significant differences were present 5, 15 and 25 min after 0.12% isoflurane when compared with air and nitrous oxide (P less than 0.01). In contrast, there was little difference between the three gases by subjective assessment.

A surgical approach to the cervicothoracic spine

We describe a method for approaching the lower cervical and upper thoracic spine, the brachial plexus and related vessels. The method involves the elevation of the medial corner of the manubrium, the sternoclavicular joint, and the medial half of the clavicle on a pedicle of the sternomastoid muscle. We have used this exposure in 17 cases with few complications and good results. Its successful performance requires high standards of anaesthesia, surgical technique and postoperative care.

Tremor in Parkinson disease: acute response to oral levodopa

A single blind placebo-controlled study has been performed in order to investigate objectively the acute tremorolytic effect of oral L-Dopa in ten parkinsonians chronically treated with L-Dopa. Finger tremor was assessed by means of a computerized accelerometer method, at rest and during maintenance of a fixed posture. Both resting and postural tremor were significantly influenced by L-Dopa. An "acute test" with oral L-Dopa, especially when different tremor components are investigated, may be useful for identifying objectively parkinsonians whose tremor does not respond to drug therapy or shows a deterioration of drug-responsiveness.

The effect of theophylline on thyrotoxic tremor

1. The effect of intravenous aminophylline on theophylline-induced tremor were studied in six hyperthyroid patients before and after treatment to euthyroidism. 2. Baseline tremor power was significantly greater in the hyperthyroid compared with the euthyroid state (P less than 0.05). 3. Aminophylline produced a significantly greater increase in tremor power in the hyperthyroid compared with euthyroid state. 4. There was a significant increase in plasma theophylline clearance and reduction in t1/2 elimination when patients were hyperthyroid but volume of distribution did not change. 5. Intravenous aminophylline potentiates the tremor produced in hyperthyroidism despite an increase in plasma theophylline clearance. A pharmacodynamic mechanism is therefore likely.

Operations to restore elbow flexion after brachial plexus injuries

We have reviewed 50 patients at a mean period of 2.7 years after operations to restore elbow flexion lost as a result of traction injuries of the brachial plexus. A variety of operations were used and, in general, patient satisfaction was high. Objectively, however, the power in the transferred muscles was poor; less than half of the patients had a significant improvement in function. Poor control of the shoulder often compromised the result. Latissimus dorsi and triceps transfers proved most reliable, and some Steindler flexorplasties also gave satisfactory results. Pectoralis major transfers were disappointing and we do not recommend their use in women.

Effect of drugs, hormones and electrical field stimulation on isolated muscle strips from human choledochoduodenal junction

The behaviour of in vitro strips from the human choledochoduodenal junction would appear to be related to the anatomical location of origin of the strip. Strips from the papillary region showed low tone and obvious spontaneous rhythmic contractions (0 X 5-6/min). Strips from the region of the inferior choledochal sphincter showed, in ten out of fifteen specimens, spontaneous myogenic tone and gave a relaxation or a biphasic response (relaxation followed by contraction) to electrical field stimulation (0 X 3 ms pulses at 10 Hz for 5 s). All strips from human choledochoduodenal junction are remarkably insensitive to a variety of gastrointestinal hormones and to opioid agents.

Computerised axial tomography in traction injuries of the brachial plexus

Severe traction injuries may damage the brachial plexus at any level from the spinal cord to the axillary outlet. Investigation aims to determine the level of the injury for each of the nerves, trunks or cords, with particular reference to obtaining firm evidence of any intradural (pre-ganglionic) damage. We report the results of computerised axial tomography of the cervical spine in comparison with conventional myelography and with surgical exploration of the plexus. CT scanning with contrast enhancement greatly improves diagnostic accuracy, particularly at C5 and C6 root levels.

Exercise-induced hand tremor: a possible test for beta 2-adrenoceptor selectivity in man?

The effects of intravenous doses of propranolol, sotalol, timolol, atenolol and placebo on exercise-induced tachycardia and exercise-induced increases in hand tremor were assessed in four healthy volunteers. All active drugs produced significant reductions in exercise-induced tachycardia. Exercise caused consistent significant increases in hand tremor which were blocked by the three non-cardioselective drugs but not by atenolol or placebo. The blockade of exercise-induced hand tremor is suggested as a possible test for the assessment of the selectivity of beta-adrenoceptor blockade in man.

Human cognitive function following binedaline (50 mg and 100 mg) and imipramine (75 mg): results with a new battery on tests

The effects of two single oral doses of binedaline (50 and 100 mg), imipramine (75 mg) and placebo were compared on a range of psychological tasks (logical reasoning, the Stroop test, and five-choice serial reaction) in healthy young volunteers. The tasks, together with a mood adjective check-list, were completed prior to drug administration and 1, 2, 4 and 8 h post-dose. Binedaline had no significant effect on any of the task parameters. Imipramine impaired performance on all but the Stroop test at 2 h after drug administration. At 1, 2 and 4 h, ratings on the "deactivation" dimension of the mood adjective check-list were significantly higher following imipramine when compared to placebo. The results are discussed in terms of some general considerations about the selection and scoring of tasks to be used in the screening of drugs.

Comparison of the effects of therapeutic doses of meptazinol and a dextropropoxyphene/paracetamol mixture alone and in combination with ethanol on ventilatory function and saccadic eye movements

The respiratory and psychomotor effects of a single oral dose of meptazinol (200 mg) and dextropropoxyphene (65 mg)/paracetamol (650 mg) mixture, was compared alone and in combination with ethanol (0.8 g kg-1). Peak saccade velocity following meptazinol or the dextropropoxyphene/paracetamol mixture was not significantly different from placebo. When each of the treatments was followed by ethanol administration, a significant decrease in saccade velocity (P less than 0.01) was seen. Given alone, neither of the analgesic drugs produced a significant change in the slope of the ventilatory response to hypercapnia. Ethanol did not affect the ventilatory response to hypercapnia when given alone or in combination with meptazinol, but when given with the dextropropoxyphene/paracetamol mixture, a significant reduction in the slope of the ventilatory response to hypercapnia occurred at 1.5 h (P less than 0.05) and 2 h (P less than 0.01) after administration of the analgesic drug. No pharmacokinetic interaction was demonstrated between ethanol and meptazinol or the dextropropoxyphene/paracetamol mixture in the doses used. In contrast to meptazinol, the dextropropoxyphene/paracetamol mixture interacts with ethanol on the ventilatory function.

Effect of drugs and electrical field stimulation on circular muscle strips from human lower oesophagus

Sphincteric muscle from human lower oesophagus may be identifiable in vitro by its ability to develop a very high level of tone (sustained resting tension). Circular muscle strips from human lower oesophagus generally behave in a similar manner to strips from the opossum oesophagus with respect to development of tone, responses to electrical field stimulation and responses to a variety of drugs. Pharmacological analysis of responses to field stimulation in strips from the region of the oesophago-gastric junction suggests that the typical biphasic response (relaxation followed by an after-contraction) is mediated by nerves which are neither adrenergic nor cholinergic. Of the substances examined only vasoactive intestinal peptide (VIP) cannot be excluded as a possible candidate for the role of inhibitory transmitter. The mechanism producing the after-contraction is not clear but it would seem unlikely that this is simply a rebound contraction. The after-contraction can be blocked independently of the relaxation by a variety of agents and is potentiated by metoclopramide.

Tremor: an alternative approach for investigating adrenergic mechanisms in thyrotoxicosis?

The effects of nadolol (or placebo) and carbimazole on thyrotoxic tremor were investigated in 18 thyrotoxic patients. Both nadolol and carbimazole produced significant reductions in tremor power although nadolol did not cause any change in serum free tri-iodothyronine and free thyroxine concentrations. The results are discussed in terms of the pathogenesis of thyrotoxic tremor and the potential usefulness of tremor in the investigation of adrenergic mechanisms in thyrotoxicosis.

The tremorolytic action of beta-adrenoceptor blockers in essential, physiological and isoprenaline-induced tremor is mediated by beta-adrenoceptors located in a deep peripheral compartment

The effects of intravenous propranolol 100 micrograms kg-1, sotalol 500 micrograms kg-1, timolol 7.8 micrograms kg-1, atenolol 125 micrograms kg-1 and placebo on essential, physiological and isoprenaline-induced tremor were studied. These beta-adrenoceptor blocker doses produced equal reduction of standing-induced tachycardia in essential tremor patients. Atenolol produced significantly less reduction of essential and isoprenaline-induced tremor than the non-selective drugs, confirming the importance of beta 2-adrenoceptor blockade in these effects. Propranolol and sotalol produced equal maximal inhibition of isoprenaline-induced tremor but propranolol was significantly more effective in reducing essential tremor. The rate of development of the tremorolytic effect was similar in essential, physiological and isoprenaline-induced tremors but all tremor responses developed significantly more slowly than the heart rate responses. It is proposed that these results indicate that the tremorolytic activity of beta-adrenoceptor blockers in essential, physiological and isoprenaline-induced tremor is exerted via the same beta 2-adrenoceptors located in a deep peripheral compartment which is thought to be in the muscle spindles.

Differential effects of alpha-adrenoceptor blockade on essential, physiological and isoprenaline-induced tremor: evidence for a central origin of essential tremor

Intravenous thymoxamine reduced the power of essential tremor but increased that of physiological and isoprenaline-induced tremor. These findings indicate that essential and physiological tremor have dissimilar pathophysiological mechanisms. They also suggest that central adrenergic mechanisms are involved in the pathophysiology of essential tremor and that isoprenaline-induced tremor is not a good model of essential tremor. Furthermore, alpha-adrenoceptor blockers may be a useful therapy for essential tremor.

Analysis of assay errors in drug measurements from the Heathcontrol interlaboratory quality assessment schemes

Measurements of drug concentrations from the Heathcontrol quality assessment schemes were analysed to detect the presence of intralaboratory, interlaboratory, or intermethod errors. We developed weighted least-squares regression procedures as significance tests for evaluating intralaboratory noise, curvature vs linearity, proportional errors and additive errors. The latter intercept test for additive errors was unsatisfactory and an effective alternative based on the difference between measurements and estimates of the true drug concentrations was developed. Significance of residuals was tested against the population noise, which was defined by smooth mathematical functions fitted to the standard deviation (SD) data for the drug samples. We evaluated these tests for 1,647 sets of data. Only small amounts of curvature were present, validating the linear-regression approach. Both random and proportional errors were demonstrated. The most frequent errors were additive in nature, components of which were demonstrated to be the result of intermethod differences.