Anaemia is independently associated with mortality in patients with hepatocellular carcinoma.

BACKGROUND: Anaemia is frequent in patients with cancer and/or liver cirrhosis and is associated with impaired quality of life. Here, we investigated the impact of anaemia on overall survival (OS) and clinical characteristics in patients with hepatocellular carcinoma (HCC). MATERIALS AND METHODS: HCC patients treated between 1992 and 2018 at the Medical University of Vienna were retrospectively analysed. Anaemia was defined as haemoglobin level <13 g/dl in men and <12 g/dl in women. RESULTS: Of 1262 assessable patients, 555 (44.0%) had anaemia. The main aetiologies of HCC were alcohol-related liver disease (n = 502; 39.8%) and chronic hepatitis C (n = 375; 29.7%). Anaemia was significantly associated with impaired liver function, portal hypertension, more advanced Barcelona Clinic Liver Cancer stage and elevated C-reactive protein (CRP). In univariable analysis, anaemia was significantly associated with shorter median OS [9.5 months, 95% confidence interval (95% CI) 7.3-11.6 months] versus patients without anaemia (21.5 months, 95% CI 18.3-24.7 months) (P < 0.001). In multivariable analysis adjusted for age, Model for End-stage Liver Disease, number of tumour nodules, size of the largest nodule, macrovascular invasion, extrahepatic spread, first treatment line, alpha-fetoprotein and CRP, anaemia remained an independent predictor of mortality (adjusted hazard ratio 1.23, 95% CI 1.06-1.43, P = 0.006). CONCLUSIONS: Anaemia was significantly associated with mortality in HCC patients, independent of established liver- and tumour-related prognostic factors. Whether adequate management of anaemia can improve outcome of HCC patients needs further evaluation.

Clinical characteristics and outcome of patients with combined hepatocellular-cholangiocarcinoma-a European multicenter cohort.

BACKGROUND: There is no clear consensus on the optimal systemic treatment regimen in combined hepatocellular-cholangiocarcinoma (cHCC-CCA) patients. We describe clinical characteristics and outcome of cHCC-CCA patients, with a special focus on patients receiving palliative systemic therapy, including immune checkpoint inhibitors (ICIs). METHODS: In this European retrospective, multicenter study, patients with histologically proven cHCC-CCA treated at four institutions between April 2003 and June 2022 were included. In patients receiving palliative systemic therapy, outcome was compared between cytotoxic chemotherapy (CHT)- and non-cytotoxic CHT (nCHT)-treated patients. RESULTS: Of 101 patients, the majority were male (n = 70, 69%) with a mean age of 64.6 ± 10.6 years. Only type of first-line treatment was independently associated with overall survival (OS). Palliative systemic therapy was administered to 44 (44%) patients. Of those, 25 (57%) patients received CHT and 19 (43%) had nCHT (n = 16 of them sorafenib) in systemic first line. Although there was no significant difference in overall response rate (ORR; CHT versus nCHT: 8% versus 5%), disease control rate (24% versus 21%), and median progression-free survival {3.0 months [95% confidence interval (CI) 1.4-4.6 months] versus 3.2 months (95% CI 2.8-3.6 months), P = 0.725}, there was a trend towards longer median OS in the CHT group [15.5 months (95% CI 8.0-23.0 months) versus 5.3 months (95% CI 0-12.5 months), P = 0.052]. However, in multivariable analysis, type of first-line regimen (CHT versus sorafenib) was not associated with OS. ORR in patients receiving ICIs (n = 7) was 29%. CONCLUSIONS: In patients with cHCC-CCA, OS, progression-free survival, ORR, and disease control rate were not significantly different between individuals receiving CHT and patients receiving nCHT. Immunotherapy may be effective in a subset of patients. Prospective studies are needed to identify optimal systemic treatment regimens in cHCC-CCA.

Cancer and hepatic steatosis.

Non-alcoholic fatty liver disease (NAFLD) is a highly prevalent and increasing liver disease, which encompasses a variety of liver diseases of different severity. NAFLD can lead to liver cirrhosis with all its complications as well as hepatocellular carcinoma (HCC). Steatosis of the liver is not only related to obesity and other metabolic risk factors, but can also be caused by several drugs, including certain cytotoxic chemotherapeutic agents. In patients undergoing liver surgery, hepatic steatosis is associated with an increased risk of post-operative morbidity and mortality. This review paper summarizes implications of hepatic steatosis on the management of patients with cancer. Specifically, we discuss the epidemiological trends, pathophysiological mechanisms, and management of NAFLD, and its role as a leading cause of liver cancer. We elaborate on factors promoting immunosuppression in patients with NAFLD-related HCC and how this may affect the efficacy of immunotherapy. We also summarize the mechanisms and clinical course of chemotherapy-induced acute steatohepatitis (CASH) and its implications on cancer treatment, especially in patients undergoing liver resection.

Non-selective ß-blockers improve the correlation of liver stiffness and portal pressure in advanced cirrhosis.

BACKGROUND: Liver stiffness (LS) correlates with portal pressure (hepatic venous pressure gradient, HVPG). However, the dynamic components of portal hypertension (PHT) in advanced cirrhosis may not be adequately assessed by TE. The influence of treatment with non-selective ß-blockers (NSBB) on the correlation of HVPG and LS has not been investigated. METHODS: One hundred and twenty-two patients with esophageal varices were included. LS, hemodynamic parameters, and HVPG were recorded at baseline (BL) and after 6 weeks of treatment with NSBB (FU). The correlation of LS and HVPG was compared to control patients with HVPG ≤ 12 mmHg. RESULTS: Patients with higher Child-Pugh stages (A:88/B:25/C:9) had higher levels of liver stiffness (47.4 ± 16.5 vs. 70.3 ± 7.9 vs. 73.7 ± 2.1 kPa) and HVPG (21 ± 5 vs. 26 ± 5 vs. 26 ± 4 mmHg). The correlation of LS and HVPG was stronger in controls with HVPG ≤ 12 mmHg (R = 0.951; P < 0.0001) than in patients with HVPG > 12 mmHg (R = 0.538; P = 0.0004). The association of HVPG with LS became stronger under treatment with NSBB, which finally restored the linear correlation of HVPG and LS (R = 0.930; P < 0.0001). Forty-three percent (53/122) of patients were hemodynamic responders to NSBB. The improvement in the correlation of LS and HVPG under NSBB was mainly noted in hemodynamic responders (R = 0.864), but not in nonresponders (R = 0.535), whereas changes in LS, heart rate, and MAP were similar in responders and nonresponders. CONCLUSIONS: Targeting the hyperdynamic circulation and the increased splanchnic blood inflow by treatment with NSBB unmasks the linear (mechanical) correlation of HVPG and LS in patients with HVPG > 12 mmHg. Measurement of LS by TE is not a feasible method to assess the dynamic components of PHT.

The effects of sorafenib on the portal hypertensive syndrome in patients with liver cirrhosis and hepatocellular carcinoma--a pilot study.

BACKGROUND: Increased intrahepatic vascular resistance and hyperperfusion in the splanchnic circulation are the principal mechanisms leading to portal hypertension in cirrhosis. Several preclinical studies have demonstrated a beneficial effect of the multikinase inhibitor sorafenib on the portal hypertensive syndrome. AIM: To investigate the effect of sorafenib on hepatic venous pressure gradient (HVPG), systemic hemodynamics and intrahepatic mRNA expression of proangiogenic, profibrogenic and proinflammatory genes. METHODS: Patients with liver fibrosis/cirrhosis and hepatocellular carcinoma were treated with sorafenib 400 mg b.d. HVPG measurement and transjugular liver biopsy were performed at baseline and at week 2. Changes in HVPG and intrahepatic mRNA expression of vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), RhoA, tumour necrosis factor-alpha (TNF-α) and placental growth factor (PlGF) were evaluated. RESULTS: Thirteen patients (m/f = 12/1; Child-Pugh class A/B = 10/3) were included. The most common aetiology of liver disease was alcohol consumption (n = 7). Eleven patients had an elevated portal pressure, including eight patients with clinically significant portal hypertension. A significant decrease of HVPG (≥ 20% from baseline) was observed in four subjects. In HVPG responders, we observed mRNA downregulation of VEGF, PDGF, PlGF, RhoA kinase and TNF-α, while no substantial mRNA decrease was found in nonresponders in any of the five genes. In two of the four HVPG responders we observed a dramatic (43-85%) mRNA decrease of all five investigated genes. CONCLUSION: Larger controlled clinical trials are needed to demonstrate any potential beneficial effect of sorafenib on portal hypertension in patients with cirrhosis.

Prognostic factors in patients with advanced hepatocellular carcinoma treated with sorafenib.

BACKGROUND: Sorafenib is the new reference standard for patients with advanced hepatocellular carcinoma (HCC). AIM: To identify prognostic factors in sorafenib-treated HCC patients and to evaluate outcomes with respect to liver function. METHODS: In this retrospective study, 148 HCC patients received sorafenib 400 mg b.d. across 11 Austrian institutions. Seventy-eight HCC patients who received best supportive care (BSC) in the pre-sorafenib era served as a control. RESULTS: In sorafenib-treated patients, low baseline α-fetoprotein, low Child-Pugh (CP) score, compensated cirrhosis, and low baseline aspartate aminotransferase (AST) were associated with significantly longer overall survival (OS) on univariate analysis. CP score and baseline AST remained independent prognostic factors on multivariate analysis. In patients with Barcelona Clinic liver Cancer (BCLC) stage B or C HCC (sorafenib: n = 139; BSC: n = 39), CP-A patients had a median OS of 11.3 (sorafenib [n = 76]) vs. 6.4 (BSC [n = 17]) months (P = 0.010), and CP-B patients had a median OS of 5.5 (sorafenib [n = 55]) vs. 1.9 (BSC [n = 22]) months (P = 0.021). In the sorafenib group, median OS according to baseline AST was 11.8 (<100 U/L [n = 58]) vs. 3.9 (≥100 U/L [n = 15]) months for CP-A patients (P = 0.127), and 6.5 (<100 U/L [n = 33]) vs. 2.1 (≥100 U/L [n = 21]) months for CP-B patients (P = 0.011). There was no survival difference between sorafenib and BSC in patients with BCLC stage D HCC (1.5 vs. 1.4 months; P = 0.116). CONCLUSIONS: Sorafenib was associated with improved survival in both CP-A and CP-B patients. In CP-B patients, baseline AST may be helpful in determining which patients are most likely to benefit from sorafenib.

[Inflammatory bowel disease--familial and sporadic form]. / Idiopatické strevní zánety--familiární a sporadická forma.

THE AIM: The aim of this thesis was to elucidate more differences between a familial and sporadic inflammatory bowel disease by comparing certain clinical data. METHODS: We assessed 248 patients with inflammatory bowel disease (IBD) observed in 1994-2004 in the Academic Department of Gastroenterology at the Medical Faculty in Hradec Králové. To get information about the defined characters we obtained from the questionary and the hospital data. RESULTS: We did not identify any relationship between the onset of the disease and a certain age group, yet males seem to be more prone to familial Crohn's disease. The more frequent familial form of Crohn's disease was the fibro-stenotic one. There were no differences in the onset of the disease. We did not prove the differences in extraintestinal signs, alergy and comorbidities. We did not find any differences in therapy response in relation to the type of nutrition (enteral, parenteral) and the administration of immunosupresive drugs. The biological therapy in sporadic and familial Crohn's disease did not differ either. Surgical intervention was more frequent in Crohn's patients compared to the patients with ulcerative colitis; yet no difference was identified between familial and sporadic cases. Appendectomy carried out before the onset of the disease was later diagnosed as Crohn's disease in more instances than ulcerative colitis. CONCLUSION: We did not prove significant differences comparing certain clinical data in familial and sporadic form of inflammatory bowel disease, yet males seem to be more prone to familial Crohn's disease. Small bowel was involved more often in familial form of Crohn's disease than in sporadic form.

Antilaminaribioside and antichitobioside antibodies in inflammatory bowel disease.

Testing antilaminaribioside (ALCA) and antichitobioside (ACCA) antibodies in 89 Crohn's disease (CD), 31 ulcerative colitis (UC) and 50 controls, mean values were 38.6 and 53.0 ELISA units for CD, 34.0 and 32.6 for UC, 34.5 and 36.4 for controls, respectively. There was no significant difference of ALCA values between CD and UC (p = 0.401), CD and control subjects (p = 0.698) or UC and controls (p = 0.898). ACCA were significantly higher in CD compared with UC (p = 0.011) but not with the controls (p = 0.095). No significant difference of ACCA values between UC and controls (p = 0.107) was found. ALCA and ACCA values significantly correlated in CD (r = 0.548, p < 10(-4)) and UC (r = 0.885, p < 10(-4)) but not in controls (r = 0.153, p = 0.287). The positive predictive value for CD was only 20 (ALCA) and 8 % (ACCA), the negative ones (to exclude CD) 25 (ALCA) and 86 % (ACCA). Small and/or large bowel involvement or disease type (i.e. stenosing, perforating or inflammatory) of CD did not differ in the two values. The idea that ALCA and ACCA may be useful either to differentiate between CD, UC and healthy subjects or to stratify CD was not confirmed.

[The influence of inflammatory bowel disease on the period of conceiving]. / Vliv idiopatického strevního zánetu na interval potrebný pro pocetí pacientek.

INTRODUCTION: Crohn's disease (CD) and ulcerative colitis (UC) influence women fertility in many ways. OBJECTIVE: We tried to determine the influence of the inflammatory bowel disease on conceiving. The date of the diagnosis, localisation, form and activity at time of conception were involved. DESIGN: Retrospective study. METHODS: We assessed data from 81 patients with inflammatory bowel disease. 56 patients were diagnosed before conceiving (41 with CD, 15 with UC), 25 patients were diagnosed after pregnancy (14 with CD, 11 with UC). We assessed the period of conceiving (in months) depends on previous abdominal operation, localisation, form and activity of the disease at time of conception. The data were obtained from the questionnaire and hospital cards. RESULTS: The previous abdominal operation, the diagnosis, localisation, and the form of the disease did not influence the period necessary to conceive in patient with inflammatory bowel disease. The anoperineal localisation and activity of Crohn's disease at the time of conception extended the period necessary to conceive. CONCLUSION: Fertility of the patients with Crohn's disease depends on the activity of the disease at time of conception and anoperineal involvement. Previous abdominal operation does not influence the fertility.

Multicentre European study of thalamic stimulation for parkinsonian tremor: a 6 year follow-up.

AIM: To evaluate the results of ventral intermediate (Vim) thalamic deep brain stimulation (DBS) in patients with tremor predominant Parkinson's disease (PD) at 6 years post surgery. METHODS: This was a prolonged follow-up study of 38 patients from eight centres who participated in a multicentre study, the 1 year results of which have been published previously. Total scores as well as scores for individual items of the motor part and the disability part of the Unified Parkinson's Disease Rating Scale were used for evaluation. RESULTS: Tremor was still effectively controlled by DBS and appendicular rigidity and akinesia remained stable compared with baseline. Axial scores (speech, gait and postural instability), however, worsened, and in parallel the initial improvement in activities of daily living scores at the 1 year follow-up had disappeared at 6 years, despite sustained improvement of tremor. Remarkably, neither daily doses of dopaminergic medication nor fluctuations and dyskinesias had changed at 6 years compared with baseline in this particular patient group. CONCLUSION: This study confirms that patients with tremor dominant PD who do not present with fluctuations and dyskinesias may have a relatively benign progression of the disease. Vim DBS, although having no effect on akinesia and rigidity, is a relatively lenient surgical procedure and may still have a place for long term symptomatic control of PD tremor in selected patients.

[Significance of serum antibodies ANCA, ASCA, ABBA in diagnostics of idiopathic intestinal inflammations]. / Význam sérových protilátek ANCA, ASCA, ABBA u idiopatických strevních zánetu.

BACKGROUND: Crohn's disease and ulcerative colitis still remain a heterogeneous group of diseases with an unclear aetiology. Serologic methods play important role in their diagnosing though there is still not an ideal marker. We tried to determine the importance of serological testing of ASCA IgA, IgG, ANCA, ABBA antibodies in patients with ulcerative colitis and Crohn's disease. METHODS AND RESULTS: ASCA IgG, ASCA IgA; ANCA, ABBA antibodies and C-reactive protein were detected by indirect fluorescence assay. ASCA IgA, ASCA IgG, ABBA, ANCA were examined in 40 patients (28 Crohn's disease, 12 ulcerative colitis, 32 health controls). Specificity of ASCA IgA, IgG in CD patients was high (both 96.2%), specificity ANCA in UC 100%. ABBA antibodies had low sensitivity and specificity in both diseases. Combination of ASCA, ANCA, ABBA makes the specificity higher. CONCLUSIONS: We showed the importance of combination ASCA, ANCA with ABBA antibodies to improve the serological diagnosing of IBD.

Human lumbar cord circuitries can be activated by extrinsic tonic input to generate locomotor-like activity.

We have demonstrated that non-patterned electrical stimulation of the lumbar cord can induce stepping-like activity in the lower limbs of complete spinal cord injured individuals. This result suggested the existence of a human lumbar locomotor pattern generator, which can convert a tonic input to a rhythmic motor output. We have studied the human lumbar cord in isolation from supraspinal input but under extrinsic tonic input delivered by spinal cord stimulation. Large-diameter afferents within the posterior roots are directly depolarized by the electrical stimulation. These afferents project to motoneurons as well as to lumbar interneurons involved in the motor control of lower limbs. Stimulation at 25-50 Hz can elicit rhythmic alternating flexion/extension movements of the lower limbs in supine individuals. Reducing the tonic input frequency to 5-15 Hz initiates lower limb extension. Epidural stimulation applied during manually assisted treadmill stepping in complete spinal cord injured persons immediately increases the central state of excitability of lumbar cord networks and enhances stepping-like functional motor outputs. Sustained, non-patterned tonic input via the posterior roots can activate human lumbar cord networks. Pattern generating configurations of these multifunctional circuitries can be set-up depending on the stimulation parameters and particularly on the input frequency.

[Importance of intrathecal pain therapy]. / Stellenwert der intrathekalen Schmerztherapie.

Intraspinal drug infusion using implantable pumps and catheter systems is a safe and effective therapy for selected pain patients with severe chronic pain. It improves pain relief, reduces drug-related side effects, decreases the need for oral analgesia and enhances quality of life in a segment of chronic pain patients whose pain has not been controlled with more conservative therapies. Intrathecal drug therapy has therefore established its role in the treatment of malignant pain, benign pain and severe spasticity.Careful patient selection and management as well as a multidisciplinary approach are determinants of successful treatment. Current practices for patient selection and management, screening, drug selection, dosing and implantation for intrathecal drug delivery systems are discussed.

Stepping-like movements in humans with complete spinal cord injury induced by epidural stimulation of the lumbar cord: electromyographic study of compound muscle action potentials.

STUDY DESIGN: It has been previously demonstrated that sustained nonpatterned electric stimulation of the posterior lumbar spinal cord from the epidural space can induce stepping-like movements in subjects with chronic, complete spinal cord injury. In the present paper, we explore physiologically related components of electromyographic (EMG) recordings during the induced stepping-like activity. OBJECTIVES: To examine mechanisms underlying the stepping-like movements activated by electrical epidural stimulation of posterior lumbar cord structures. MATERIALS AND METHODS: The study is based on the assessment of epidural stimulation to control spasticity by simultaneous recordings of the electromyographic activity of quadriceps, hamstrings, tibialis anterior, and triceps surae. We examined induced muscle responses to stimulation frequencies of 2.2-50 Hz in 10 subjects classified as having a motor complete spinal cord injury (ASIA A and B). We evaluated stimulus-triggered time windows 50 ms in length from the original EMG traces. Stimulus-evoked compound muscle action potentials (CMAPs) were analyzed with reference to latency, amplitude, and shape. RESULTS: Epidural stimulation of the posterior lumbosacral cord recruited lower limb muscles in a segmental-selective way, which was characteristic for posterior root stimulation. A 2.2 Hz stimulation elicited stimulus-coupled CMAPs of short latency which were approximately half that of phasic stretch reflex latencies for the respective muscle groups. EMG amplitudes were stimulus-strength dependent. Stimulation at 5-15 and 25-50 Hz elicited sustained tonic and rhythmic activity, respectively, and initiated lower limb extension or stepping-like movements representing different levels of muscle synergies. All EMG responses, even during burst-style phases were composed of separate stimulus-triggered CMAPs with characteristic amplitude modulations. During burst-style phases, a significant increase of CMAP latencies by about 10 ms was observed. CONCLUSION: The muscle activity evoked by epidural lumbar cord stimulation as described in the present study was initiated within the posterior roots. These posterior roots muscle reflex responses (PRMRRs) to 2.2 Hz stimulation were routed through monosynaptic pathways. Sustained stimulation at 5-50 Hz engaged central spinal PRMRR components. We propose that repeated volleys delivered to the lumbar cord via the posterior roots can effectively modify the central state of spinal circuits by temporarily combining them into functional units generating integrated motor behavior of sustained extension and rhythmic flexion/extension movements. This study opens the possibility for developing neuroprostheses for activation of inherent spinal networks involved in generating functional synergistic movements using a single electrode implanted in a localized and stable region.

Initiating extension of the lower limbs in subjects with complete spinal cord injury by epidural lumbar cord stimulation.

We provide evidence that the human spinal cord is able to respond to external afferent input and to generate a sustained extension of the lower extremities when isolated from brain control. The present study demonstrates that sustained, nonpatterned electrical stimulation of the lumbosacral cord--applied at a frequency in the range of 5-15 Hz and a strength above the thresholds for twitches in the thigh and leg muscles--can initiate and retain lower-limb extension in paraplegic subjects with a long history of complete spinal cord injury. We hypothesize that the induced extension is due to tonic input applied by the epidural stimulation to primary sensory afferents. The induced volleys elicit muscle twitches (posterior root muscle-reflex responses) at short and constant latency times and coactivate the configuration of the lumbosacral interneuronal network, presumably via collaterals of the primary sensory neurons and their connectivity with this network. We speculate that the volleys induced externally to the lumbosacral network at a frequency of 5-15 Hz initiate and retain an "extension pattern generator" organization. Once established, this organization would recruit a larger population of motor units in the hip and ankle extensor muscles as compared to the flexors, resulting in an extension movement of the lower limbs. In the electromyograms of the lower-limb muscle groups, such activity is reflected as a characteristic spatiotemporal pattern of compound motor-unit potentials.

Effects of phosphoprotein phosphatase inhibitors (phenylarsine oxide and cantharidin) on Tetrahymena.

The effects of phenylarsine oxide (PAO) (phosphotyrosine phosphatase inhibitor) and cantharidin (serine/threonine phosphatase [PP2A] inhibitor) treatments were analysed on the synthesis of phospholipids and glycolipids, and on the cytoskeletal elements (F-actin and tubulin containing structures) of Tetrahymena pyriformis. Both phosphatase inhibitors reduced the amount of incorporated 32P of the whole phospholipid content, but the ratio of phosphatidylserine (PS) and phosphatidylcholine (PC) to the total phospholipid content increased. Both treatments influenced the phosphatidylinositol (PI) system. These inhibitors also influenced the incorporation of palmitic acid into the phospholipids: in general PAO decreased, whereas cantharidin increased the amount of incorporated palmitic acid; 1 microM cantharidin significantly increased the labelling of PE and PA. The incorporation of mannose and glucosamine was influenced differently by PAO and cantharidin treatments: the latter elevated, while PAO decreased the labelling of glycolipids with these sugars. The effects of these treatments were visible also in the case of confocal scanning laser microscopic (CSLM) images: after treatments with both inhibitors, the F-actin containing cortical elements were destroyed, but the tubulin containing ones (longitudinal and transversal microtubules, oral apparatus and deep fibres) did not display significant alterations. The different effects of phosphatase inhibitors were visible also on the scanning electron microscopic (sEM) images: cantharidin treatments (1 microM) decreased the amount of dissolved membrane lipids after chemical dehydration of the cells with 2, 2-dimethoxy propane (DMP), but in the case of treatments with 10 microM, the surface pattern of cells was similar to the controls. On the other hand, after PAO treatments the surface pattern of Tetrahymena showed significant alterations. Both phosphatase inhibitors inhibited the phagocytotic activity of the cells. On the basis of present experiments we suppose that these treatments are able to influence signalling systems (e.g. PI) of Tetrahymena, and also the structure of the cytoskeleton and the functions (e.g. phagocytosis) which are connected with skeletal elements.

Sodium channel inactivation in an animal model of acute quadriplegic myopathy.

We previously demonstrated that muscle fibers become unable to fire action potentials in both patients and an animal model of acute quadriplegic myopathy (AQM). In the animal model, skeletal muscle is denervated in rats treated with high-dose corticosteroids (steroid-denervated; SD), and muscle fibers become inexcitable despite resting potentials and membrane resistances similar to those of control denervated fibers that remain excitable. We show here that unexcitability of SD fibers is due to increased inactivation of sodium channels at the resting potential of affected fibers. A hyperpolarizing shift in the voltage dependence of inactivation in combination with the depolarization of the resting potential induced by denervation results in inexcitability. Our findings suggest that paralysis in the animal model of AQM is the result of an abnormality in the voltage dependence of sodium channel inactivation.