Guillain-Barré Syndrome and Unilateral Optic Neuritis Following Vaccination for COVID-19: A Case Report and Literature Review.

A 71-year-old woman presented 2 weeks after vaccination with the first dose of Vaxzevria (AstraZeneca, Oxford) for COVID-19 with a left lower motor neuron facial nerve palsy, which progressed to bilateral involvement. This was accompanied by bilateral proximal leg weakness. She was diagnosed with the 'facial diplegia with paraesthesia' variant of Guillain-Barré syndrome. Seven weeks post vaccination she developed painless loss of vision in the right eye. The visual acuity in that eye was light perception only with a right relative afferent pupillary defect and right optic disc swelling. A diagnosis of optic neuritis was made and she received pulsed intravenous methylprednisolone for 3 days, followed by oral prednisolone. The optic neuritis recurred following initial cessation of steroids requiring an extended course of steroids. Despite this, she made a good visual recovery to 6/6 in the affected eye. We present this case and a review of the literature surrounding vaccination and the development of these conditions.

Exploring strategies used following a group-based fatigue management programme for people with multiple sclerosis (FACETS) via the Fatigue Management Strategies Questionnaire (FMSQ).

OBJECTIVES: To explore cross-sectional patterns of use of fatigue management strategies in people with multiple sclerosis (MS) who had attended a group-based fatigue management programme, Fatigue: Applying Cognitive behavioural and Energy effectiveness Techniques to lifeStyle ('FACETS'). In a multicentre randomised controlled trial (RCT) the FACETS programme was shown to reduce fatigue severity and improve self-efficacy and quality of life. DESIGN: A questionnaire substudy within a RCT involving the self-completed Fatigue Management Strategies Questionnaire (FMSQ). The FMSQ includes: (1) closed questions about the use and helpfulness of fatigue management strategies taught in FACETS and (2) open items about changes to lifestyle, attitudes or expectations, barriers or difficulties encountered and helpful strategies not covered in FACETS. PARTICIPANTS: All had a clinical diagnosis of MS, significant fatigue, were ambulatory and had attended at least 4 of 6 scheduled FACETS sessions. METHODS: Participants (n=72) were posted the FMSQ with a prepaid return envelope 4 months after the end of the FACETS programme. RESULTS: 82% (59/72) of participants returned the FMSQ. The fatigue management strategies most frequently used since attending FACETS were prioritisation (80%), pacing (78%), saying no to others (78%), grading tasks (75%) and challenging unhelpful thoughts (71%). Adding in those participants who were already using the respective strategies prior to FACETS, the three most used strategies at 4 months were prioritisation (55/59), grading (54/59) and pacing (53/58). Free-text comments illustrated the complex interplay between attitudes/expectations, behaviours, emotions and the environment. Issues related to expectations featured strongly in participants' comments. Expectations (from self and others) were both facilitators and barriers to effective fatigue management. CONCLUSIONS: Individuals' comments highlighted the complex, multifaceted nature of fatigue management. Revising expectations and a greater acceptance of fatigue were important shifts following the programme. Findings support the relevance of a cognitive behavioural approach for fatigue management. Booster sessions might be a useful addition to the FACETS programme. TRIAL REGISTRATION NUMBER: Current controlled trials ISRCTN76517470; Results.

Short-term incubation of equine laminar veins with cortisol and insulin alters contractility in vitro: possible implications for the pathogenesis of equine laminitis.

This study investigated the effects of cortisol and insulin, hormones that affect both glycaemic status and vascular function, on the in vitro contractility of isolated healthy equine small laminar veins. Small veins (150-500 µm) draining the digital laminae from healthy horses or ponies were investigated by wire myography. Concentration response curves were constructed for noradrenaline (NA), phenylephrine (PE), endothelin-1 (ET-1) and 5-hydroxytryptamine (5-HT) in the presence of either cortisol (10(-6 ) m) or insulin (1000 µIU/mL). Cortisol significantly increased the maximum contractility of laminar veins to the vasoconstrictors NA and 5-HT but decreased the maximal contraction to ET-1. Insulin decreased the contractility of vessels to PE and ET-1. It is possible that short-term cortisol excess could enhance venoconstrictor responses to 5-HT and NA in laminar veins in vivo, thereby predisposing to laminitis. Additionally, a reduction in the ability of insulin to counteract alpha-adrenoreceptor and ET-1-mediated contraction, likely to occur in subjects with insulin resistance, may further exacerbate venoconstriction in animals prone to laminitis. These mechanisms may also predispose horses with disorders such as equine Cushing's disease and equine metabolic syndrome to laminitis.

Calpainopathy presenting as foot drop in a 41 year old.

Mutations in the gene encoding muscle-specific calpain 3 protease cause limb girdle muscular dystrophy type 2A. Calpainopathy is characterised by progressive symmetrical atrophy of pelvic, scapular and trunk muscles with an elevated creatine kinase. Most patients develop symptoms in childhood and lose the ability to walk by the age of 40 years. We describe a man who presented with foot drop at the age of 41 years, together with neurophysiological, histopathological and genetic data. This is the first report of calpainopathy presenting as foot drop, and widens the phenotype associated with this disease.

Development and preliminary evaluation of a cognitive behavioural approach to fatigue management in people with multiple sclerosis.

OBJECTIVES: (i) To develop a group-based intervention for the management of multiple sclerosis (MS) fatigue incorporating energy effectiveness and cognitive behavioural approaches and (ii) to undertake a process and preliminary evaluation. METHODS: Drawing upon a literature search, a local model of good practice and the views of service users and health professionals, a manualised group-based fatigue management programme was developed, designed to be delivered by health professionals. A process and preliminary outcome evaluation was undertaken. Sixteen participants attended across two iterations. Participant feedback, obtained via a focus group and evaluation questionnaires, was used to refine the programme. Outcomes were collected pre- and post-programme (including fatigue severity, quality of life, self-efficacy). RESULTS: Focus group feedback suggested the programme was well received, reflected in high attendance and positive ratings on evaluation questionnaires. At follow-up, despite the small sample size, there were significant improvements in perceived self-efficacy for managing fatigue. CONCLUSION: An evidence-based fatigue management intervention has been developed and preliminary findings look promising. In the next phase we will examine whether the programme transfers satisfactorily to other centres and collect data in preparation for a randomised controlled trial (RCT). PRACTICE IMPLICATIONS: Implications for practice will emerge when the results of our RCT are published.

Endothelin mediated contraction of equine laminar veins.

REASONS FOR PERFORMING STUDY: Endothelin-1 (ET-1) may be a key mediator in the pathogenesis of laminitis, but endothelin-mediated responses in the venous microcirculation of the equine foot have yet to be fully characterised. OBJECTIVES: To characterise the response of equine laminar veins to ET-1 and evaluate the ET-1 receptor subtypes that mediate this response. METHODS: Small veins (150-500 microns) draining the equine digital laminae from healthy horses and ponies subjected to euthanasia at an abattoir were investigated using wire myography. Concentration response curves were constructed for ET-1 in the presence of ETA (BQ123) and ETB (BQ788) receptor antagonists, and L-NAME, a nitric oxide synthase blocker. The selective ETB receptor agonist BQ3020 was investigated alone and following incubation with L-NAME, with or without BQ788. RESULTS: Endothelin-1 contraction of laminar veins was significantly inhibited by BQ123 but not by BQ788. In the presence of L-NAME, sensitivity of laminar veins to ET-1 was enhanced 4-fold, and further addition of BQ788 did not alter this increased sensitivity. BQ3020 induced no venoconstriction; however, in the presence of L-NAME, it caused contraction of veins with approximately 30% of the efficacy of ET-1. The action of BQ3020 in the presence of L-NAME was abolished by BQ788. CONCLUSIONS: Both ETA and ETB receptors are involved in the net tonic response to ET-1 in normal laminar veins. A population of ETB receptors may be present on the vascular endothelium and on smooth muscle of laminar veins, and the action of ET-1 at these 2 sites is likely to be approximately equal and opposite. POTENTIAL RELEVANCE: Our results clarify the function of the ET-1 receptor subtypes in laminar veins from healthy horses. Further study of ET-1 receptors in laminitic horses is therefore warranted.

Endothelium-dependent relaxation is resistant to inhibition of nitric oxide synthesis, but sensitive to blockade of calcium-activated potassium channels in essential hypertension.

In human essential hypertension (EH), endothelium-dependent relaxation can occur independent of nitric oxide (NO) and prostacyclin (PGI(2)). Recent in vivo data suggest that rapid compensatory upregulation of endothelial cytochrome P450 epoxygenase 2C9 occurs to preserve vasorelaxation under conditions of decreased NO bioavailability. As one of the vascular actions of CYP2C9 is to modulate small and intermediate conductance endothelial calcium-activated potassium channels (SK(Ca) and IK(Ca)), we examined whether endothelium-dependent relaxation is sensitive to inhibitors of these channels (apamin and charybdotoxin) in resistance-sized vessels from human with EH. Subcutaneous gluteal biopsies were performed on 12 humans with EH and 12 matched control subjects. Resistance arteries were dissected and relaxation responses to carbachol were assessed ex vivo using wire myography in the presence of: (i) N(G)-nitro-L-arginine (L-NOARG)/indomethacin; and (ii) apamin/charybdotoxin. Maximal carbachol relaxation was impaired in EH vs control subjects. No differences in responses were observed with the endothelium-independent agonist, S-nitroso-N-acetyl-penicillamine. Relaxation to carbachol was attenuated following incubation with L-NOARG/indomethacin in vessels from control subjects (P<0.01 analysis of variance (ANOVA)), but not in vessels from patients with EH. The reverse pattern was seen following apamin/charybdotoxin with carbachol relaxation attenuated only in EH vessels (P<0.001 ANOVA). Endothelium-dependent relaxation is resistant to endothelial nitric oxide synthase inhibition but sensitive to blockade of calcium-activated potassium channels in human EH. Studies with more specific inhibitors are required to determine whether this response is mediated by endothelial potassium channel subtypes (SK(Ca) and IK(Ca)).

Psychological interventions for multiple sclerosis.

BACKGROUND: The unpredictable, variable nature of Multiple Sclerosis (MS), and the possibility of increasing disability, means that a diagnosis can have substantial psychological consequences. OBJECTIVES: To assess the effectiveness of psychological interventions for people with MS. SEARCH STRATEGY: We searched 19 databases up to December 2004; Cochrane MS Group Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, PsychINFO, CINAHL and 14 others. We searched reference lists of articles, wrote to corresponding authors of the 13 papers identified by June 2004, and searched for trials in progress using 3 research registers. SELECTION CRITERIA: Randomised controlled trials of interventions described as wholly or mostly based on psychological theory and practice, in people with MS. Primary outcome measures were disease specific and general quality of life, psychiatric symptoms, psychological functioning, disability, and cognitive outcomes. Secondary outcome measures were number of relapses, pain, fatigue, health care utilisation, changes in medication, and adherence to other therapies. DATA COLLECTION AND ANALYSIS: Pertinent studies were identified from abstracts by one author. Full papers were independently compared to selection criteria by four authors. Key details were extracted from relevant papers using a standard format, and studies scored on three dimensions of quality. The review is organised into four mini-reviews (MR) dependent on the intervention's target population; people with cognitive impairments (MR1), people with moderate to severe disability (MR2), people with MS (no other criteria) (MR3), and people with depression (MR4). MAIN RESULTS: Overall 16 studies were identified and included. MR1: three trials (n=145). Some evidence of effectiveness of cognitive rehabilitation on cognitive outcomes, although this was difficult to interpret because of the large number of outcome measures used. MR2: three trials (n=80). One small trial suggesting psychotherapy may help with depression. MR3: seven studies (n=688). Some evidence that cognitive behavioural therapy may help people adjust to, and cope with, having MS (three trials). The other trials were diverse in nature and some difficult to interpret because of multiple outcome measures. MR4: three trials (n=93). Two small studies of cognitive behavioural therapy showed significant improvements in depression. AUTHORS' CONCLUSIONS: The diversity of psychological interventions identified indicates the many ways in which they can potentially help people with MS. No definite conclusions can be made from this review. However there is reasonable evidence that cognitive behavioural approaches are beneficial in the treatment of depression, and in helping people adjust to, and cope with, having MS.

Glioma after cerebral hydatid disease.

BACKGROUND: The authors present the case of a 31-year-old man with a malignant glioma. He had been treated for cerebral hydatid as a child, and 22 years later he developed a glioma at the site of his previous disease. DISCUSSION: Could chronic inflammatory change following intracranial hydatid disease have induced neoplastic transformation of glial cells?

The use of fluorescent nuclear dyes and laser scanning confocal microscopy to study the cellular aspects of arterial remodelling in human subjects with critical limb ischaemia.

Resistance arteries isolated from patients with critical limb ischaemia (CLI), a hypotensive/hypoperfusion state of the lower leg, have been shown to undergo morphological changes opposite to those observed in hypertension, that is, decreased wall thickness, reduced cross-sectional area and a decreased wall : lumen ratio. The aim of this present study was to use laser scanning confocal microscopy (LSCM) to study intact resistance arteries isolated from patients with CLI, specifically to identify the cellular aspects of the morphological changes identified in ischaemic subcutaneous and skeletal muscle resistance vessels. Using LSCM, a significant reduction in adventitial and medial thickness, cross-sectional area and wall : lumen ratio was confirmed in resistance arteries from both distal ischaemic subcutaneous and skeletal muscle vascular beds when compared with corresponding arteries from the proximal non-ischaemic sites. The cellular composition of the adventitial, medial and intimal layers of these distal ischaemic arteries was significantly different compared with proximal non-ischaemic arteries. These differences in the distal arteries were characterised by hypoplasia in the adventitial and medial layers of the arterial wall and hypertrophy in the intimal layer. The differences observed in both distal ischaemic vascular beds (subcutaneous and skeletal muscle) were similar.

Possible underascertainment of variant Creutzfeldt-Jakob disease: a systematic study.

OBJECTIVES: To predict the size of the vCJD epidemic it is important to know whether the description of cases of vCJD in 1996 represent the first cases of a new disease entity or whether detection was due to increased surveillance of CJD in humans. Detection of earlier cases would suggest a shorter incubation period and might lead to predictions of epidemic size being revised. METHODS: All certified deaths (excluding external injury and poisoning) in residents of Wales aged 15-45, between 1985 and 1995, were reviewed to detect vCJD deaths that might have been overlooked. 12 091 deaths were reviewed. "Non-specific fatal disorders compatible with vCJD" were defined. Deaths recorded to diseases other than those defined were rejected from further analysis (8769). Remaining cases (3322) were subdivided. Group A comprised deaths recorded to suicide, transport accidents, and those that could not be ascertained (ICD9 rubrics E950-959, E800-848, and 7999), a total of 2698 cases. Group B comprised deaths due to neurological disease, psychiatric disease, or substance abuse (624). RESULTS: For group A, remaining brain material was identified (n=218, 8.1%) and examined by routine histology and immunocytochemistry for prion protein. No cases of vCJD were detected. For group B, review of remaining clinical information was undertaken. Of 624 cases, information was available on 447 (72%). Brain tissue was examined by routine histology and immunocytochemistry in 47 (7.5%) cases. Sufficient clinical and pathological information was available to exclude all these as potential cases of vCJD. CONCLUSION: Variant CJD is a new disease entity and not simply the result of better case ascertainment.

Hormone replacement therapy can augment vascular relaxation in post-menopausal women with type 2 diabetes.

BACKGROUND: Diabetes is a major risk factor for coronary heart disease in women and event rates increase substantially after the menopause. Observational studies have suggested that estrogens may provide cardioprotection by regulating endothelial nitric oxide synthase. METHODS: In order to examine the effect of hormone replacement therapy (HRT) on endothelium-dependent and -independent vascular relaxation in post-menopausal women with type 2 diabetes, an open study was conducted in which gluteal biopsies were collected from 17 women before and after 6 months of transdermal 17 beta-estradiol (80 microg twice weekly) in combination with oral norethisterone (1 mg daily). Small arteries (<550 microm) were dissected from fat and mounted on a wire myograph for assessment of relaxation in response to acetylcholine (ACh), bradykinin (BK) and sodium nitroprusside (SNP). RESULTS: Maximal relaxation responses to ACh, BK and SNP in women with diabetes and non-diabetic control subjects were 52 +/- 8 versus 96 +/- 2% (P < 0.05), 76 +/- 7 versus 97 +/- 1%, (P < 0.05) and 91 +/- 2 versus 98 +/- 1% (P < 0.05) respectively. After 6 months of HRT, maximal relaxation responses to ACh, BK and SNP in women with diabetes (compared with pre-HRT) were: 88 +/- 4 (P < 0.05), 93 +/- 3 (P < 0.05) and 98 +/- 1% (P < 0.05) respectively. At baseline and after HRT, EC50 (concentration required to obtain 50% of maximum response) data exhibited similar changes. CONCLUSIONS: HRT had potentially beneficial effects on vascular relaxation. Data were consistent with improvements in endothelial function, vascular smooth muscle function, or both. Controlled studies are required to confirm and extend these findings.

Insulin-mediated vasorelaxation in pregnancy.

OBJECTIVE: To investigate insulin-mediated vasorelaxation in pregnancy, and the role of nitric oxide in this response. DESIGN: In vitro study of isolated subcutaneous resistance arteries from pregnant and non-pregnant women. METHODS: Small arteries (mean vessel diameter <300 microm) were isolated from biopsies of subcutaneous fat from 14 pregnant and seven non-pregnant women. Insulin-mediated attenuation of the vasoconstriction response to noradrenaline, before and after nitric oxide synthase inhibition, was studied in isolated arteries using wire myography. Vessel responses to noradrenaline following incubation with insulin were also tested after endothelial denudation. Maximum responses were compared using one-way ANOVA and Bonferroni's post hoc test for multiple comparisons. RESULTS: In pregnancy, the maximum vasoconstriction produced by noradrenaline was increased (P < 0.01). Insulin significantly reduced this response in pregnant women (P < 0.01), while inhibition of nitric oxide synthase with Nomega-nitro-L-arginine methyl ester (L-NAME) resulted in potentiation (P < 0.05). Following inhibition of nitric oxide synthase with L-NAME, addition of the insulin was still able to produce a significant attenuation in maximum vasoconstriction to noradrenaline in pregnant women (P < 0.01). Furthermore, the absence of functioning endothelium did not abolish the attenuating effect of the insulin on noradrenaline-induced vasoconstriction in pregnant women (P < 0.01). CONCLUSIONS: The vasodilatory effect of insulin is not diminished in pregnancy, despite the development of insulin resistance. Furthermore, the attenuation of vasoconstrictor tone is via an endothelium-independent mechanism. This suggests that the vascular dysfunction associated with diabetes mellitus does not occur with physiological insulin resistance.

Vasoconstrictor effect of the angiotensin-converting enzyme-resistant, chymase-specific substrate [Pro(11)(D)-Ala(12)] angiotensin I in human dorsal hand veins: in vivo demonstration of non-ace production of angiotensin II in humans.

BACKGROUND: [Pro(11)(D)-Ala(12)] angiotensin I is an ACE-resistant substrate specific for chymase. We used this peptide to determine whether a functionally significant non-ACE angiotensin (Ang) II-generating pathway exists in human dorsal hand veins. METHODS AND RESULTS: Using a modified Aellig technique, we studied the response to Ang I and [Pro(11)(D)-Ala(12)] Ang I in dorsal hand veins in vivo in patients with coronary heart disease. We measured the venoconstrictor effect of each peptide given before and after a 6.25-mg oral dose of the ACE inhibitor captopril or matching placebo. Placebo or captopril was given in a double-blind, randomized fashion. Ang I induced a mean+/-SEM venoconstrictor response of 45+/-11%, 40+/-10%, 55+/-8%, and 4+/-4% before placebo, after placebo, before captopril, and after captopril, respectively. Hence, the response to Ang I was reproducible and was reduced significantly only after treatment with captopril (P=0.002). [Pro(11)(D)-Ala(12)] Ang I induced a mean venoconstrictor response of 42+/-9%, 49+/-9%, 48+/-10%, and 54+/-11% before placebo, after placebo, before captopril, and after captopril, respectively. Hence, captopril had no significant effect on the response to [Pro(11)(D)-Ala(12)] Ang I. CONCLUSIONS: We have demonstrated that [Pro(11)(D)-Ala(12)] Ang I is able to induce venoconstriction in humans in vivo. With this specific pharmacological probe, we have shown that a non-ACE pathway capable of generating Ang II exists in human veins in vivo and is potentially functionally important. This pathway is likely to involve the enzyme chymase.

The effect of type 1 diabetes mellitus on vascular responses to endothelin-1 in pregnant women.

Diabetes is associated with vascular dysfunction, which may be due in part to altered vascular responses to endogenous peptides such as endothelin-1. These altered responses may also contribute to the decreased maternal peripheral resistance in pregnancy. The aim of this study was to examine the effect of diabetes on the vasoconstrictor response to endothelin-1 in pregnant women. Small arteries were isolated from nine healthy pregnant, seven type 1 diabetic pregnant women, and five healthy nonpregnant women. Contraction curves were performed on a wire myograph for noradrenaline (1 nM to 30 microM) and endothelin-1 (1 pM to 0.3 microM). Maximum responses and sensitivity were compared by t test. No differences in maximum response to noradrenaline or potassium were seen among the three groups. The maximum response to endothelin-1 was significantly increased in pregnancy (P < 0.05), whereas endothelin-1 sensitivity was reduced in the diabetic compared with the nondiabetic pregnant women (P < 0.05). Pregnant women have an increased maximum vasoconstriction response to endothelin-1 compared with nonpregnant women, whereas diabetic pregnant women demonstrate reduced sensitivity to endothelin-1. These observations suggest that endothelin-1 may play a role in maintaining peripheral vascular tone in normal pregnancy, and the decreased sensitivity seen in pregnant women with diabetes may reflect abnormal vascular reactivity.

Non-hepatic hyperammonaemia: an important, potentially reversible cause of encephalopathy.

The clinical syndrome of encephalopathy is most often encountered in the context of decompensated liver disease and the diagnosis is usually clear cut. Non-hepatic causes of encephalopathy are rarer and tend to present to a wide range of medical specialties with variable and episodic symptoms. Delay can result in the development of potentially life threatening complications, such as seizures and coma. Early recognition is vital. A history of similar episodes or clinical risk factors and early assessment of blood ammonia levels help establish the diagnosis. In addition to adequate supportive care, investigation of the underlying cause of the hyperammonaemia is essential and its reversal, where possible, will often result in complete recovery. Detection of an unborn error of metabolism should lead to the initiation of appropriate maintenance therapy and genetic counselling.

Functional characterization of alpha1-adrenoceptor subtypes in human subcutaneous resistance arteries.

The functional characteristics of the alpha1-adrenoceptor subtypes in human resistance arteries are still not clear. We recently reported that the alpha1A-adrenoceptor predominantly mediates contraction to norepinephrine in human skeletal muscle resistance arteries. In this study we extended these investigations to human subcutaneous resistance arteries. Arterial segments were isolated from the inguinal subcutaneous fat and mounted on a small vessel wire myograph. Potencies of agonists and antagonists were examined. N-[5-(4,5-dihydro-1H-imidazol-2yl)-2-hydroxy-5,6,7,8-tetrahydronaphthalen-1-yl]methanesulphonamide (A-61603) was found to be 10- and 54-fold more potent than norepinephrine and phenylephrine, respectively. Brimonidine (UK 14304) evoked significantly smaller contractile responses than norepinephrine and phenylephrine, showing the presence of a small population of alpha2-adrenoceptors in these arteries, and this was confirmed by the studies with selective alpha1- and alpha2-adrenoceptor antagonists prazosin and (8aR,12aS,13aS)-5,8,8a,9,10,11,12,12a,13a-decahydro-3-methoxyl-12-(ethylsulphonyl)-6H-isoquino[2,1-g][1,6]-naphthyridine (RS 79948). Prazosin, 5-methyl-urapidil, and 2-[2,6-dimethoxyphenoxyethyl]aminomethyl)-1,4-benzodioxane (WB 4101) shifted the potency of norepinephrine concentration dependently giving pA2 values of 9.4, 8.9, and 10.1, respectively, showing the presence of the alpha1A-subtype in these arteries. Pretreatment with 1 and 10 microM chloroethylclonidine did not affect the potency of and maximum responses to norepinephrine, ruling out the presence of the alpha1B-subtype in these arteries. 8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspiro[4.5]decane-7,9-dione (BMY 7378, 10 and 100 nM) did not affect the potency of norepinephrine but a small shift was observed by 1 microM BMY 7378, giving a pK(B) value of 7.1, much less than that reported for the alpha1D-subtype. These results suggest the predominant involvement of alpha1A-adrenoceptor in the contractile responses to norepinephrine in these arteries. The physiological role of this subtype in the maintenance of peripheral arterial resistance is yet to be confirmed.

Effect of neutral endopeptidase inhibition on the actions of adrenomedullin and endothelin-1 in resistance arteries from patients with chronic heart failure.

Adrenomedullin and endothelin are novel peptides that are produced in the blood vessel wall and have contrasting biologic actions. Both may play a pathophysiological role in atherosclerosis and chronic heart failure. It has also been suggested that both peptides may be metabolized by neutral endopeptidase and that pharmacological manipulation of this enzyme may be of therapeutic interest. We investigated the effect of thiorphan, a neutral endopeptidase inhibitor, on the vasodilator response to adrenomedullin and the vasoconstrictor response to endothelin in small resistance arteries taken from patients with heart failure caused by coronary heart disease. Small resistance arteries were dissected from gluteal biopsy samples and studied with wire myography. Thiorphan did not affect the vasodilator response to adrenomedullin in arteries preconstricted with norepinephrine. Maximal responses were 66% (SD 11%) and 72% (8%) in the absence and presence of thiorphan, respectively (n=8). The vasoconstrictor response to endothelin was also unaffected. The maximum vasoconstrictor responses in the absence and presence of thiorphan were 152% (11%) and 132% (12%), respectively (n=8). The values of corresponding -log concentrations of agonist required to effect a 50% response (pD(2)) were 8.52 (0.11) and 8.64 (0.15), respectively. We showed that the inhibition of neutral endopeptidase does not augment the vasodilator and vasoconstrictor activities of adrenomedullin and endothelin, respectively, in small resistance arteries from patients with chronic heart failure. This suggests that neutral endopeptidase inhibition, as a therapeutic strategy, will enhance neither the potentially desirable vascular actions of adrenomedullin nor the potentially unfavorable vascular effects of endothelin-1 in human cardiovascular disease states.

Effects of adrenomedullin on angiotensin II stimulated atrial natriuretic peptide and arginine vasopressin secretion in healthy humans.

AIMS: Adrenomedullin is a newly described peptide that has widespread tissue distribution. Its presence in cardiovascular (including vascular endothelial cells, smooth muscle cells, and cardiac atria and ventricles) and renal tissues, together with its vasodilatory and natriuretic properties, suggest a role in blood pressure regulation and fluid and electrolyte balance. METHODS: Nine normal volunteers were studied to determine whether or not adrenomedullin influenced plasma atrial natriuretic peptide and arginine vasopressin concentrations during systemic angiotensin II infusion. RESULTS: A significant (P = 0.02) augmentation of atrial natriuretic peptide concentrations, but no suppression of arginine vasopressin concentrations, was found with coinfusion of adrenomedullin and angiotensin II when compared with vehicle and angiotensin II. CONCLUSIONS: Despite its vasodilator and natriuretic action, adrenomedullin significantly augmented angiotensin II-stimulated plasma atrial natriuretic peptide concentrations in healthy humans. This provides further evidence of a synergistic interaction between adrenomedullin and atrial natriuretic peptide and suggests that adrenomedullin may have a role in fluid and electrolyte balance and blood pressure regulation.