Efficacy of Vedolizumab for Refractory Pouchitis of the Ileo-anal Pouch: Results From a Multicenter US Cohort

BACKGROUND AND AIMS

Inflammation of the pouch after ileal pouch-anal anastomosis (IPAA) can significantly impact quality of life and be difficult to treat. We assessed the effectiveness and safety of vedolizumab in Crohn's disease (CD) of the pouch and chronic antibiotic-dependent or antibiotic-refractory pouchitis.

METHODS

This was a retrospective, multicenter cohort study at 5 academic referral centers in the United States. Adult patients with endoscopic inflammation of the pouch who received vedolizumab were included. The primary outcome was clinical response at any time point. Secondary outcomes included clinical remission, endoscopic response, and remission. Univariate analysis and multivariate analysis were performed for the effect of the following variables on clinical response: fistula, onset of pouchitis less than 1 year after IPAA, younger than 35 years old, gender, previous tumor necrosis factor inhibitor-alpha use, and BMI >30.

RESULTS

Eighty-three patients were treated with vedolizumab for inflammation of the pouch between January 2014 and October 2017. Median follow-up was 1.3 years (interquartile range 0.7-2.1). The proportion of patients that achieved at least a clinical response was 71.1%, with 19.3% achieving clinical remission. Of the 74 patients with a follow-up pouchoscopy, the proportion of patients with endoscopic response and mucosal healing was 54.1% and 17.6%, respectively. Patients who developed pouchitis symptoms less than 1 year after undergoing IPAA were less likely to respond to vedolizumab, even after controlling for other risk factors.

CONCLUSIONS

Vedolizumab is safe and effective in the management of CD of the pouch and chronic pouchitis. Further studies are needed to compare vedolizumab with other biologic therapies for pouchitis and CD of the pouch.

Smoking Interacts With CHRNA5, a Nicotinic Acetylcholine Receptor Subunit Gene, to Influence the Risk of IBD-Related Surgery

BACKGROUND

Inflammatory bowel disease (IBD) is a chronic luminal disease with genetic and environmental factors affecting phenotype. This study evaluated the relationship between CHRNA5, a nicotinic receptor subunit gene, and smoking in predicting IBD-related surgery as well as the relationship between CHRNA5 and nicotine dependence.

METHODS

Participants completed a smoking questionnaire and were genotyped for CHRNA5 rs16969968. Demographic and clinical data were obtained from medical records. Wilcoxon, ANOVA, Chi square, and Fisher's exact tests were used for comparisons. Logistic regression was used to evaluate the effect of clinical and genetic predictors on surgery, stratified by disease subtype given paradoxical effects of smoking. Kaplan-Meier curves were used to examine the effect of smoking and genotype on time to surgery. (Significance: P < 0.05 for main effects; P < 0.2 for interaction terms).

RESULTS

400 (65.8%) patients had Crohn's disease (CD) and 208 (34.2%) had ulcerative colitis (UC). 298 (49%) underwent an IBD-related surgery. There was a trend towards significance between rs16969968 and smoking behavior (smoking status [P = 0.05], nicotine dependence [AA > AG > GG; P = 0.08]). Smoking and genotype were not independently associated with surgery in UC or CD. However, interaction between rs16969968 and smoking in predicting surgery was observed for both UC (OR = 2.72; P = 0.05) and CD (OR = 2.88; P = 0.1). CHRNA5 genotype, but not smoking, predicted time to surgery in patients with UC (P = 0.007) but not in patients with CD. The interaction between smoking and genotype was not significantly associated with time to surgery in UC or CD.

CONCLUSIONS

The CHRNA5 rs16969968 A variant interacts with smoking to influence IBD-related surgery. 10.1093/ibd/izx094_video1izx094.video15775248538001.

Vedolizumab Effectiveness and Safety Over the First Year of Use in an IBD Clinical Practice

BACKGROUND AND AIMS

Vedolizumab inhibits leucocyte vascular adhesion and migration into the gastrointestinal tract through α4β7 integrin blockade. This agent became available in mid-2014 for the treatment of moderate to severe Crohn's disease (CD) and UC (UC). The aim of this study was to assess the patterns of use, effectiveness and safety of vedolizumab in an inflammatory bowel disease (IBD) clinical practice.

METHODS

Patients beginning vedolizumab were enrolled with informed consent. A prospective cohort was followed with laboratory, disease activity and quality-of-life assessments made during infusion visits up to week 14. Duration of vedolizumab use, mucosal healing and safety were analysed retrospectively for all patients not captured in the prospective component of this study.

RESULTS

One hundred and two patients started vedolizumab, with 51 patients (30 CD, 21 UC) followed prospectively. The CD patients exhibited a significant decrease in Crohn's Disease Activity Index (p = 0.04) and Harvey-Bradshaw index (p < 0.01) by week 14. The UC patients demonstrated improved partial Mayo scores at weeks 6 (p < 0.01) and 14 (p < 0.001). Ninety percent of all CD and UC patients remained on vedolizumab up to week 14. IBD-related quality of life was improved by week 6 in CD and UC cohorts (p = 0.02 and p < 0.01 respectively). Colectomy for lack of response and systemic histoplamosis were notable reasons for early discontinuation of vedolizumab, which was otherwise well tolerated.

CONCLUSIONS

Vedolizumab was efficacious and a high percentage of patients continued this therapy beyond induction dosing. Observed safety signals may be attributed to the refractory IBD disease state of this early-adopting clinical cohort.

Obesity is Associated With Poor Surgical Outcome in Crohn's Disease

BACKGROUND

Published data suggest a link between obesity and adverse outcomes in Crohn's disease (CD). We aimed to test the hypothesis that obese CD patients would be more likely than non-obese CD patients to have poor surgical outcome when undergoing surgery for a complication of CD.

METHODS

We designed a retrospective cohort study to test our hypothesis. The population comprised of adult CD patients who underwent CD related surgery at a tertiary referral center. The exposed and unexposed cohorts were represented by patients who were obese vs. non-obese at the pre-op visit respectively. Outcome was represented by successful vs. unsuccessful surgical outcome as deemed by the treating clinician.

RESULTS

Ninety CD patients were eligible for inclusion into this cohort study of which 36 were obese (exposed cohort) and 54 were non-obese (unexposed cohort). Among obese CD patients, 64% had an unsuccessful surgical outcome vs. 41% with unsuccessful surgical outcome among the non-obese. Based on unadjusted bivariate analysis, potential confounders identified included age and type of surgery. Gender distribution, disease duration, ethnicity, tobacco use, steroid use, traditional and biological immune modulator use and clinical disease activity were similar between the two groups. Logistic regression adjusted for age and type of surgery revealed that obese CD patients were approximately 2.5 times more likely to have a poor surgical outcome than patients with CD who were not obese (P = 0.05 OR 2.53 95% CI 0.99 - 6.52). BMI as a continuous variable (adjusted for age and type of surgery) appeared to be associated with poor surgical outcome (P = 0.06 OR 1.07 95% CI 0.99 - 1.15).

CONCLUSIONS

Obesity may be associated with poor surgical outcome in CD patients.

Clinical experience of natalizumab in Crohn's disease patients in a restricted distribution program

BACKGROUND

Natalizumab (NAT) is a humanized monoclonal antibody against a4-integrin initially approved for the treatment of multiple sclerosis, and then withdrawn from the market in 2005 due to the risk of progressive multifocal leukoencephalopathy. NAT was approved for the treatment of Crohn's disease in the United States in 2008 under a restricted distribution program. There has been limited data on NAT since then. The purpose of this study was to review the experience with NAT in Crohn's disease patients at a tertiary inflammatory bowel disease center.

METHODS

A retrospective chart review was performed on all patients who received NAT for treatment of refractory Crohn's disease from January 2008 to August 2010 at Washington University Medical Center in St. Louis.

RESULTS

A total of 20 patients were identified and included in our study. Four patients did not complete induction therapy. Seven patients had a clinical response, with 5 patients continuing treatment up to 2012. Four patients had a partial response, 3 had adverse events, and 2 experienced loss of response. Two patients were pregnant while on NAT, and neither had significant adverse pregnancy outcomes. One patient dependent on total parenteral nutrition developed recurrent line sepsis while on NAT. Of the 5 patients on long-term maintenance therapy, 4 have a positive anti-JC virus antibody. No patients developed progressive multifocal leukoencephalopathy or other neurological complications.

CONCLUSION

NAT remains a valuable alternative treatment option for patients with refractory Crohn's disease under a restricted distribution program.

Clinical experience of natalizumab in Crohn's disease patients in a restricted distribution program

Background

Natalizumab (NAT) is a humanized monoclonal antibody against a4-integrin initially approved for the treatment of multiple sclerosis, and then withdrawn from the market in 2005 due to the risk of progressive multifocal leukoencephalopathy. NAT was approved for the treatment of Crohn's disease in the United States in 2008 under a restricted distribution program. There has been limited data on NAT since then. The purpose of this study was to review the experience with NAT in Crohn's disease patients at a tertiary inflammatory bowel disease center.

Methods

A retrospective chart review was performed on all patients who received NAT for treatment of refractory Crohn's disease from January 2008 to August 2010 at Washington University Medical Center in St. Louis.

Results

A total of 20 patients were identified and included in our study. Four patients did not complete induction therapy. Seven patients had a clinical response, with 5 patients continuing treatment up to 2012. Four patients had a partial response, 3 had adverse events, and 2 experienced loss of response. Two patients were pregnant while on NAT, and neither had significant adverse pregnancy outcomes. One patient dependent on total parenteral nutrition developed recurrent line sepsis while on NAT. Of the 5 patients on long-term maintenance therapy, 4 have a positive anti-JC virus antibody. No patients developed progressive multifocal leukoencephalopathy or other neurological complications.

Conclusion

NAT remains a valuable alternative treatment option for patients with refractory Crohn's disease under a restricted distribution program.

Increased sensitivity through maximizing the extinction ratio of SOI delay-interferometer receiver for 10G DPSK

We present an optimized design for a 10G- differential-phase-shift-keyed (DPSK) receiver based on a silicon-on-insulator (SOI) unbalanced tunable Mach-Zehnder interferometer (MZI) switch in sequence with a Mach-Zehnder delay interferometer (MZDI). The proposed design eliminates the limitation in sensitivity of the device produced by the waveguide propagation losses in the delay line. A 2.3 dB increase in receiver sensitivity at a bit-error-rate (BER) of 10(-9) is experimentally measured over a standard implementation. The enhanced sensitivity is achieved with zero power consumption by tuning the operating wavelength or with less than 5 mW for a fixed wavelength using microheaters. Also the foot-print of the device is minimized to 0.11 mm(2) by the use of compact spirals.

Detection of genetic polymorphism among and within Echinococcus granulosus strains by heteroduplex analysis of a microsatellite from the U1 snRNA genes

Polymerase chain reaction of a pentanucleotide microsatellite in the U1 snRNA gene complex generated a multiple band pattern due to the priming of paralogous sequences. Denaturation and slow renaturation of polymerase chain reaction products allow the formation of heteroduplex DNA that can be detected by its differential mobility in polyacrylamide gel electrophoresis. Heteroduplex analysis was used to determine if the U1 snRNA microsatellite could be a useful genetic marker in Echinococcus granulosus. A U1 snRNA microsatellite fragment from E. granulosus was isolated and characterized by Southern blot and sequencing. Four E. granulosus strains were analyzed: sheep, Tasmanian sheep, cattle, and camel strains. The former two showed polymorphism and shared three of the six patterns found for sheep strain. The cattle strain displayed two patterns, and the camel strain was monomorphic. The electrophoretic profiles were used for statistical analysis in order to determine genetic distance and the relationship among strains. Heteroduplex analysis can be helpful in genotyping E. granulosus strains and is useful in detecting polymorphism within strains.

High polymorphism in genes encoding antigen B from human infecting strains of Echinococcus granulosus

Echinococcus granulosus antigen B (AgB) is encoded by a gene family and is involved in the evasion of the host immune response. E. granulosus exists as a number of strains (G1-G10) that differ in biological characteristics. We used PCR-SSCP followed by DNA sequencing to evaluate sequence variation and transcription profile of AgB in 5 E. granulosus strains. Twenty-four genomic sequences were isolated and clustered in 3 groups related to 2 of the 5 reported AgB genes. AgB4 genes were present in almost all strains, whereas AgB2 were present as functional genes exclusively in G1/G2 cluster, and as non-functional genes in G5 and the G6/G7 cluster, suggesting inter-strain variation. The AgB transcription patterns, analysed by RT-PCR, showed that AgB2 and AgB4 genes were transcribed in G1, while only the AgB4 gene was transcribed in G7 strain. Cysts from the same strain or cluster shared more genomic and cDNA variants than cysts from different strain or cluster. The level of nucleotide and deduced amino acid sequence variation observed is higher than that reported so far for coding genes of other helminths. Neutrality was rejected for AgB2 genes. These data show the genetic polymorphism of antigen-coding genes among genetically characterized strains of E. granulosus.

Livestock trade history, geography, and parasite strains: the mitochondrial genetic structure of Echinococcus granulosus in Argentina

A sample of 114 isolates of Echinococcus granulosus (Cestoda: Taeniidae) collected from different host species and sites in Argentina has been sequenced for 391 bp from the mitochondrial cytochrome c oxidase subunit I gene to analyze genetic variability and population structure. Nine different haplotypes were identified, 5 of which correspond to already characterized strains. Analysis of molecular variance and nested clade analysis of the distribution of haplotypes among localities within 3 main geographic regions indicate that geographic differentiation accounts for the overall pattern of genetic variability in E. granulosus populations. Significant geographic differentiation is also present when the sheep strain alone is considered. Our results suggest that geographic patterns are not due to actual restricted gene flow between regions but are rather a consequence of past history, probably related to the time and origin of livestock introduction in Argentina.

Isolation and characterization of microsatellites from the tapeworm Echinococcus granulosus

The Echinococcus granulosus genome was searched for microsatellites using 8 different repeated oligonucleotides as probes (GT15, CT15, AT15, CG15, CAT10, CAA10, CGG10 and CATA10). Southern blot experiments revealed that DNA regions containing GT, CAA, CATA and CT repeats are the most frequent in the E. granulosus genome. AT and CG probes showed no hybridization signal. Two loci containing CA/GT (Egmsca1 and Egmsca2) and 1 locus containing GA/CT (Egmsga1) repeats were cloned and sequenced. The locus Egmsca1 was analysed in 73 isolates from Brazil and Argentina whose strains were previously characterized. Brazilian isolates from cattle strain and Argentinean isolates from camel strain were monomorphic and shared the allele (CA)7. Argentinean isolates of sheep and Tasmanian sheep strains shared 2 alleles [(CA)8 and (CA)10] with Brazilian isolates of sheep strain. The allele (CA)11 was found only in Brazilian isolates of sheep strain at a low frequency. The Brazilian and the Argentinean sheep strain populations were tested for the Hardy-Weinberg equilibrium, and only the former was in agreement with the expectations. No polymorphism was found among individual protoscoleces from a single hydatid cyst, validating the utilization of pooled protoscoleces from 1 cyst, grouped as an isolate, in population studies. This work describes for the first time the isolation and characterization of microsatellites from E. granulosus.

Growth hormones reverse desensitization of P2Y(2) receptors in rat mesangial cells

Rat glomerular mesangial cells (GMC) express P2Y(2) purinoceptors and respond to nucleotide stimuli with a transient increase in the cytosolic Ca(2+) concentration and the receptors desensitize upon repeated stimulation with nucleotide. We demonstrate that there is a cross-talk from the signaling of tyrosine kinase to P2Y(2) receptors. For most cells repeated applications of ATP completely abolished the response, as did activation of PKC with 500 nM PMA. In contrast, preincubation with the PKC inhibitor chelerythrine (100 nM) prevented desensitization. Desensitization after application of ATP was reversed by subsequent incubation with PDGF-BB (50 ng/ml) or insulin (660 mU/ml). We conclude that the desensitization is caused by phosphorylation due to PKC and is under the control of growth factors. The findings support the hypothesis that growth hormones potentiate nucleotides as proinflammatory mediators and we hypothesize that they have bearing on the hyperfiltration seen in diabetes.

Trace elements and electrolytes in human resting mixed saliva after exercise

OBJECTIVES

Exercise is known to cause changes in the concentration of salivary components such as amylase, Na, and Cl. The aim of this investigation was to evaluate the effect of physical exercise on the levels of trace elements and electrolytes in whole (mixed) saliva.

METHODS

Forty subjects performed a maximal exercise test on a cycle ergometer. Samples of saliva were obtained before and immediately after the exercise test. Sample concentrations of Fe, Mg, Sc, Cr, Mn, Co, Cu, Zn, Se, Sr, Ag, Sb, Cs, and Hg were determined by inductively coupled plasma mass spectrometry and concentrations of Ca and Na by atomic absorption spectrometry.

RESULTS

After exercise, Mg and Na levels showed a significant increase (p < 0.05) while Mn levels fell (p < 0.05). Zn/Cu molar ratios were unaffected by exercise.

CONCLUSIONS

Intense physical exercise induced changes in the concentrations of only three (Na, Mg, and Mn) of the 16 elements analysed in the saliva samples. Further research is needed to assess the clinical implications of these findings.

Ca2+ response of rat mesangial cells to ATP analogues

The aim of this investigation was to characterise the effects of ATP analogues and UTP on the single cell intracellular Ca2+ concentration ([Ca2+]i) in cultured rat mesangial cells. Typically, there were two phases in the Ca2+ response to the agonists, an initial fast transient peak and a subsequent slower decline, or plateau, phase. For the peak amplitude in [Ca2+]i the agonists had about equal effect. But when taking in consideration the percentage of responding cells and the integrated Ca2+ response over 1 min, the order of efficacy of nucleotide agonists (100 microM) was UTP = ATP > ATPgammaS > ADP = 2MeS-ATP (2-methylthio-ATP). Adenosine, AMP and beta,gamma-Me-ATP (100 microM) had no effect. Suramine (100 microM) and reactive blue (50 microM) decreased the number of responding cells. Removing Ca2+ from the bath diminished neither the peak in [Ca2+]i nor the percentage of responding cells, but the average [Ca2+]i increase in 1 min was significantly reduced. The results indicate that P2Y2 receptors are present in rat mesangial cells but it cannot be excluded that there are receptors distinct from P2Y2 which also mediate a rise in [Ca2+]i.

Effects of stimulation and inhibition of protein kinase C on the cytosolic calcium concentration in rabbit afferent arterioles

The effect of the protein kinase C (PKC) inhibitor chelerytrine (Ch) and the PKC activator 12-0-tetradecanoyl-phorbol-13-acetate (TPA) on the cytosolic calcium concentration ([Ca2+]i) in isolated intact rabbit afferent arterioles was investigated. [Ca2+]i was measured in the proximal and distal parts of the arteriole. Administration of 1 microM Ch gave rise to a peak followed by an elevated level of [Ca2+]i in both these parts. Neither the peak nor the elevated level of [Ca2+]i was significantly reduced by 1 microM nifedipine. The relative peak increase in [Ca2+]i in response to 1 microM noradrenaline (NA) or to 10 nM angiotensin II (AII) was significantly blunted in both parts after preincubation with 1 microM Ch. Depolarization with 25 mM K+ increased [Ca2+]i in both parts. Preincubation with Ch did not affect the increase in [Ca2+]i induced by 25 mM K+. TPA (10 and 100 nM) did not significantly affect the basal [Ca2+]i in the afferent arteriole. The [Ca2+]i response to NA or 25 mM K+ was not affected by TPA. We conclude that blockade of PKC increases [Ca2+]i in afferent arteriolar smooth muscle by a mechanism independent of L-type voltage-sensitive calcium channels. Inhibition of PKC blunts the relative increase in [Ca2+]i in response to AII and, to a lesser extent, that induced by NA. We conclude that PKC might be important in modulating the calcium changes that occur in response to these vasoconstrictors.

Cell calcium concentration in glomerular afferent and efferent arterioles under the action of noradrenaline and angiotensin II

The glomerular arterioles in the juxtaglomerular apparatus seem to function as effectors of the tubuloglomerular feedback mechanism. In this mechanism increased delivery of fluid to the distal nephron activates the macula densa cells through transport via an Na-2Cl-K cotransporter. This activation may lead to vasoconstriction of the afferent arteriole. Furthermore, vasoactive substances seem to affect both afferent and efferent arterioles. There are morphological differences along the afferent arteriole, some parts containing epithelioid cells with renin granules and others regular smooth muscle cells. The aim of the present experiments was to determine whether noradrenaline (10(-6) M) and angiotensin II (10(-6) M) had differential effects on the cell calcium concentration [Ca2+]i and on contraction in isolated perfused afferent and efferent arterioles and in the mesangial region. [Ca2+]i was measured with fura-2, an intensified videocamera and a digital imaging system. From the proximal to the distal part of the arteriole [Ca2+]i increased from about 100 to 250 nM. A [Ca2+]i increase and a contraction were caused by noradrenaline alone in the proximal part of the afferent arteriole and by angiotensin II alone in the distal part of this arteriole. In the mesangial region there was a high basal [Ca2+]i but no response to the vasoactive substances. In the efferent arteriole, application of both noradrenaline and angiotensin II led to an increase in [Ca2+]i and a contraction. The present experiments indicate that the two vasoactive substances tested act in a similar fashion along the whole length of the efferent arteriole, while in the afferent arteriole their actions are not equally distributed.

Net uptake of lactate by rabbit hindlimb during hypoxia

Lactate uptake by normoxic tissues is a pH-dependent phenomenon that occurs with increases in arterial lactate concentration. In this study we sought to determine the effect of hypoxia on lactate uptake by the rabbit hindlimb at different arterial blood pH (pHa). Two groups of rabbits were subjected to 20 min of arterial hypoxemia (PaO2 approximately 20 mm Hg). One group was allowed to maintain normal pHa (approximately 7.40 to 7.45; n = 5), whereas the other group was hyperventilated, resulting in hypocarbia and alkalemia (pHa > 7.50; n = 5). Lactate uptake was computed from measurements of femoral blood flow and the arterio-venous lactate difference. We found decreases in hindlimb O2 consumption during hypoxemia from 0.79 +/- 0.08 to 0.33 +/- 0.06 ml/min in the normal pH group (p < 0.01) and from 0.49 +/- 0.06 to 0.24 +/- 0.02 ml/min in the high pH group (p < 0.01). At that time there was net uptake of lactate by the hindlimb of the normal pH group (8.1 +/- 2.0 mumol/min; p < 0.001) and lactate release by the alkalemic group (1.61 +/- 1.0 mumol/min). Furthermore, hindlimb lactate uptake was associated with increased glucose consumption (p < 0.001). We hypothesize that the mechanisms responsible for lactate uptake by resting skeletal muscle during hypoxia may be similar to those that regulate lactate uptake during normoxic exercise.

Role of tissue hypoxia as the mechanism of lactic acidosis during E. coli endotoxemia

We compared the hemodynamic and metabolic alterations produced in rabbits by similar decreases in cardiac output created by inflating a balloon placed in the right ventricle (n = 6) with those produced by an intravenous bolus of Escherichia coli lipopolysaccharide (LPS; SEP group; n = 6). We measured O2 consumption (VO2), O2 transport (TO2), and O2 extraction ratio (ERO2) for the whole animal and also for the left hindlimb. Both groups experienced similar decreases in cardiac output, systemic TO2, and VO2 and similar increases in ERO2. For the hindlimb, TO2 was similar, but VO2 and ERO2 were lower for the SEP group 30 min after LPS administration (P less than 0.05); however, this difference disappeared during the remainder of the experiment. Arterial lactate concentration was greater (P less than 0.05) for the SEP group. There were no differences in skeletal muscle PO2, measured with a multiwire surface electrode, or in cardiac and skeletal muscle concentrations of high-energy phosphates. We hypothesize that a direct effect of LPS on cellular metabolism may have resulted in greater arterial lactate concentration for the SEP group.

Myopic keratomileusis: short-term results

The first 97 eyes operated with keratomileusis by two surgeons starting to use this technique are evaluated. The 30- and 90-day postoperative results of this initial experience are reported. Average preoperative myopia was -10.53 D spherical equivalent (range -5.25 to -22.25 D); average refractive correction at 90 days was -10.20 D. Preoperative visual acuities without correction were between 0.01 and 0.15 Snellen scale (20/2000 to 20/133), and 90 days postoperatively they varied between 0.02 and 0.60 Snellen scale (20/1000 to 20/33) with an average of 0.29 (20/69). Average preoperative visual acuity with correction was 0.70 Snellen scale (20/29), and 90 days afterward it was 0.60 Snellen scale (20/33). Preoperative average refractive cylinder was 1.33 D and postoperative was 1.86 D, showing that significant amounts of astigmatism were not induced.

Abnormalities in sensory and mixed evoked potentials in ataxia-telangiectasia

Electromography, motor, sensory and mixed nerve conduction velocity, and H reflex were studied in four patients with ataxia-telangiectasia. The earliest and most striking electrophysiologial finding was the reduced amplitude of evoked nerve potentials. In the oldest patient, findings suggestive of spinal atrophy and mild reduction of the motor and sensory nerve conduction velocities were found. Reduced amplitude in the evoked nerve potentials can be observed without clinical evidence of peripheral neuropathy. Electrophysiological abnormalities are more severe in older than in young patients. Sural nerve biopsy in one patient showed mild changes: loss of the largest myelinated fibres and demyelination of some fibres. The ratio between maximum conduction velocity of the sural nerve and the diameter of the largest fibres was in the lower limits of the normal range. The resemblance between electrophysiological abnormalities in Friedreich's ataxia and ataxia-telangiectasia is discussed.