Three to four-year-old nonpassaged EGF-responsive neural progenitor cells: proliferation, apoptosis, and DNA repair

Epidermal growth factor responsive (EGFr) neural progenitor (NP) cells have been shown to be a potential alternative tissue source for neural transplantation and for developmental study. We have shown that nonpassaged EGFr NP cells can self-renew for 2 years in neurospheres and can robustly differentiate into glia and a number of neuronal cell types. We are now attempting to investigate if the EGFr NP cells will die or continue to live beyond the life span of the donor. In addition, we and other investigators have also found that EGFr NP cells, after transplant, retain only a small number of cells in the transplant site. In this study, we investigate the plasticity and fate of the EGFr NP cells. Using the nonpassaged method, we found EGFr NP cells live in the EGF supplement medium for over 4 years-the longest-lived EGFr NP cells ever reported. The 4-year-old striatal or cortical EGFr neurospheres, when subplated with substrate coating, migrate out of neurospheres and have robust growth with many processes. Furthermore, when nucleotide marker bromodeoxyuridine (BrdU) was added 3 days prior to the subplating, the EGFr NP cells were labeled positively with BrdU in the nucleus, indicating active proliferation activity. Meanwhile two other events were also found in the long-term EGFr NP cells. In the midst of the proliferation, apoptosis occurred. A subpopulation of EGFr NP cells are undergoing programmed cell death as indicated by the cell morphology and the TUNEL staining for DNA strand breaks. The TUNEL fluorescein-staining indicates that over 50% of EGFr NP cells are positive in the nuclei. On the other hand, we have also found that the major base excision repair enzyme, APE/ref-1, which is responsible for recognizing and repairing baseless sites in DNA, was present in the progenitor cells. However, in those cells undergoing apoptosis, APE/ref-1 levels were dramatically reduced or missing, and only a small percentage of cells were TUNEL and APE/ref-1 positive. These observations indicate that EGFr neural progenitor cells can live beyond the life span of the donor animal. The longevity of these cells in culture may be enhanced due to decreased apoptosis and the retention of normal DNA repair capacity.

Cross-sectional imaging of a cadaveric human heart

The precise relationship of the components of the heart can be difficult to understand. With recent developments in cardiac ultrasound and other imaging modalities, most professionals need to be familiar with cross-sectional cardiac anatomy. We have created a teaching technique based on a normal human heart removed at autopsy. It was scanned using a computed tomography scanner and the images examined in different planes. The images were annotated and used in a computer-based teaching program to convey the details of cardiac anatomy. Images corresponding to planes typically used in echocardiography were also examined. The resulting images were of high resolution and illustrated many subtle structures rarely seen in conventional studies of cardiac anatomy. This system has benefits to both clinicians and anatomists.

[Inpatient and outpatient follow-up of grade I malignant melanoma]

BACKGROUND

In 1995, the French consensus conference on management of patients with grade I malignant melanoma recommended clinical examination for patient monitoring. To date, only one survey has been conducted to evaluate these recommendations and their consequences, providing no means of assessing follow-up practices. The aim of this study was to assess follow-up practices in patients with grade I malignant melanoma followed in an outpatient private practice setting and in a hospital setting with regular appointments.

PATIENTS AND METHODS

This retrospective study was conducted in collaboration with private practice and hospital dermatologists, all members of an association of continuing medical education. Medical records of 584 patients with grade I malignant melanoma who had undergone surgery between January 1, 1991 and December 31, 1995 were reviewed. Three hundred twenty-nine patients were followed in an exclusively outpatient setting by their private dermatologist and 265 were followed in a hospital setting. Follow-up data were: age, sex, date of surgical excision of the melanoma, Breslow thickness, date of each follow-up visit, presence of possible metastases and mode of diagnosis.

RESULTS

Patient features were different in the two groups: mainly greater Breslow thickness and more frequent metastatic course in patients followed in a hospital setting. Among all patients, 65 (11 p. 100) developed metastases. Diagnosis of metastasis was made clinically in 95 p. 100 whatever the mode of monitoring considered. The number of patients lost to follow-up was 11p. 100 among those followed in a hospital setting and 42 p. 100 in those followed in a private practice setting. Patients lost to follow-up had a higher risk of developing metastasis as their average Breslow thickness was 1.7 mm.

CONCLUSION

This study shows that patients followed in a hospital setting have a more severe prognosis than patients followed in private practice. It confirms that systematic use of complementary tests is of little interest in detecting metastases since over the period considered, the diagnosis of metastasis was made clinically in most cases. It also discloses difficulties encountered in exclusively outpatient follow-up as a high number of patients were lost to follow-up in this setting. A systematic appointment fixed by the private dermatologist during the follow-up period appears to be needed to ensure good quality follow-up. Such an appointment system should help reduce the number of patients lost to follow-up.

A comparison of the reliability of self-reported drug use and sexual behaviors using computer-assisted versus face-to-face interviewing

The purpose of this study was to assess the reliability of responses to HIV risk behavior questions obtained using a voice-enhanced, computer-administered self-interview (audio-CASI) system with touch-screen response compared with those obtained via face-to-face interviews administered by trained and experienced interviewers. Additionally, the study assessed bias that may be attributable to an audio-CASI data collection format. The design of the study was a four-group crossover design with random assignment to one of four study conditions: (a) audio-CASI interview at both intake and retest, (b) face-to-face interview at both intake and retest, (c) audio-CASI interview at intake and face-to-face interview at retest, and (d) face-to-face interview at intake and audio-CASI interview at retest. The study was conducted with a sample of drug users at risk for HIV infection interviewed in nonclinical settings. Data were collected at intake and 48 hours after intake. Analyses show that data obtained using voice-enhanced computer interviewing with touch-screen response are reliable and are comparable to data obtained using interviewer administered face-to-face interviews. However, bias was found to be associated with data collection format and may be partially attributable to the complexity of the questionnaire.

Hereditary recurrent focal neuropathies: clinical and molecular features

The authors review the molecular genetics and pathophysiology of hereditary recurrent focal neuropathies: hereditary neuropathy with liability to pressure palsies (HNPP) and hereditary neuralgic amyotrophy (HNA). Significant progress in the understanding of HNPP and HNA has been achieved. HNPP and HNA are distinct clinical and pathologic disease entities with autosomal dominant inheritance. Molecular genetic studies have shown that HNPP and HNA are located on chromosome 17 but at distinct genetic loci (17p11.2 for HNPP, 17q25 for HNA). The 1.5 megabase deletion in 17p11.2 is the major cause of HNPP. This interstitial deletion causes the complete loss of one allele of the peripheral myelin protein 22 (PMP22) gene. Interestingly, rare HNPP patients are found without the 1.5 megabase deletion. However, these patients have distinct mutations in the PMP22 gene resulting in altered expression of the PMP22 protein. Current molecular genetic tests and clinical guidelines allow improved diagnosis, prognosis, and genetic counseling for patients with HNPP. Such tests are not available for HNA, because the disease-causing gene remains unknown. Molecular genetic advances in HNPP and HNA, as well as the study of transgenic animal and cellular models, will provide a more precise understanding of the disease mechanisms and will lead to the development of effective therapeutic tools for patients with inherited and sporadic recurrent peripheral neuropathies.

The effect of dietary protein source and protected methionine (Lactet) on wool growth and microbial protein synthesis in Merino wethers

With increasing awareness of the importance of controlling tender wool, there is a need to describe supplementary feeds in terms of their effects on wool growth. Since wool growth is largely a function of the quantity and quality of absorbed protein, the aim of this experiment was to compare the protein quality of different diets in relation to their ability to promote wool growth. An additional aim was to compare observed responses with those predicted using feeding models based on metabolisable protein. Sixty-four Merino weaner wethers were allocated to 8 treatment groups in a factorial design consisting of 4 diets each at 2 levels of protected methionine. The 4 roughage-based diets consisted of different protein sources: Rumentek®-protected canola meal (at 33% of the diet), oats plus urea (oats at 46% and urea at 2.6%), Lupinus angustifolius (at 36%), and L. albus (at 36%). The 2 levels of protected methionine were 0 or 3 g/day as Lactet. The diets were formulated to be isonitrogenous and isoenergetic and were fed at 1.5 × maintenance metabolisable energy. The experiment lasted 13 weeks, which included a 3-week balance collection period in which faeces and urine were collected. Wool growth in sheep fed the protected canola meal diet was 37% greater than in sheep fed oats (1.37 v. 1.0 mg/cm2 per day), and 73% greater than in sheep fed L. angustifolius (P < 0.001). Wool growth from the oat diet was 26% greater than from the L. angustifolius diet (P < 0.05). There was no effect of diet on rumen volatile fatty acid concentrations. Lactet increased wool growth by 18% across all diets (P < 0.001), representing an additional 0.17 mg/cm2 per day or 1.7 g/head per day. There were no significant differences in liveweight gain between the diets unless Lactet was added. When Lactet was added, lupins produced a significantly higher liveweight gain than oats or protected canola meal. Lactet increased mean liveweight gain by 22% across all diets (P < 0.05). Lactet also increased the concentration of plasma albumin, decreased plasma α-amino nitrogen, and increased urinary excretion of creatinine and purine derivatives (P < 0.05). The findings highlight the need to evaluate feed sources in terms of protein degradability and sulfur amino acid composition, particularly when assessing effects on wool growth. The inability of current feeding models to incorporate differences in amino acid flows, particularly sulfur amino acids, is an impediment to evaluating supplement quality in terms of wool growth.

Topical treatments for fungal infections of the skin and nails of the foot

OBJECTIVES

The objective of this review is to identify and evaluate the evidence of efficacy for topical treatments for fungal infections of the skin and nails of the human foot. To establish the effectiveness of topical treatments in achieving a cured condition and in preventing recurrence

SEARCH STRATEGY

Randomised controlled trials were identified from the MEDLINE, EMBASE and CINHAL databases, from the beginning of these databases to December 1997. Also we screened the Cochrane Controlled Trials Register, the Science Citation Index BIOSIS, CAB - Health, Healthstar and Economic databases. References and unpublished studies were searched, podiatry journals handsearched and the pharmaceutical industry contacted.

SELECTION CRITERIA

Only randomised controlled trials (RCTs) using participants who have mycologically diagnosed fungal infections of the skin and nails of the human foot are included in the analysis.

DATA COLLECTION AND ANALYSIS

Two reviewers independently summarised the included trials and appraised their quality of reporting using a structured data extraction tool which assessed 12 quality criteria.

MAIN RESULTS

Of 126 trials identified in 121 papers, 72 met the inclusion criteria. Placebo-controlled trials yielded the following pooled relative risks of failure to cure (RRFC) for skin infections: allylamines 0.30 (95% confidence interval 0.23 to 0.37); azoles 0.53 (0.42 to 0.68); undecenoic acid 0.28 (0.11 to 0.74); tolnaftate 0.46 (0.17 to 1.22). Though meta-analysis of 11 trials comparing allylamines and azoles showed an RRFC of 0.88 (0.78 to 0.99) in favour of allylamines, there was evidence of language bias. Seven English language reports favoured allylamines (RRFC = 0.79; 0.68 to 0.93) but four foreign language reports showed no difference between the two drugs (RRFC = 1.00; 0.90 to 1.12). The two trials of nail infections did not provide any evidence of benefit for topical treatments compared with placebo.

CONCLUSIONS

In placebo-controlled trials allylamines, azoles and undecenoic acid were efficacious. There are sufficient comparative trials to judge relative efficacy only between allylamines and azoles. Allylamines cure slightly more infections than azoles but are much more expensive. The most cost-effective strategy is first to treat with azoles or undecenoic acid and to use allylamines only if that fails.

Gastric response to increased meal viscosity assessed by echo-planar magnetic resonance imaging in humans

Normal meals are highly viscous, and viscosity is a key factor in influencing gastric emptying of food. However, the process of meal dilution and mixing is difficult to assess with the use of conventional methods. The aim of this study was to validate an in vivo, novel, noninvasive, echo-planar magnetic resonance imaging (EPI) technique, capable of monitoring the viscosity of a model meal, and to use this to investigate the effects of viscosity on gastric emptying, meal dilution and satiety. Healthy volunteers (n = 8) ingested 500 mL of locust bean gum (0.25, 0.5, 1.0 or 1.5 g/100 g), nonnutrient, liquid meals of varying viscosities, and labeled with a nonabsorbable marker, phenol red. Meal viscosity was calibrated against the water proton transverse relaxation rate (T(2)(-1)) in vitro before ingestion, thus viscosity was measured in vivo via EPI measurements of T(2)(-1). Viscosity and dilution were also measured directly using nasogastric aspirates. Gastric volumes as measured by EPI, fullness, appetite and hunger were also assessed serially. Before ingestion, the log of initial meal viscosity was linearly related to T(2)(-1) (n = 8, r(2) = 0.95). Similarly, T(2)(-1) measured in vivo was also linearly related to the viscosity of the aspirates (r(2) = 0.88). All meals underwent rapid dilution, leading to a reduction in viscosity, which was greatest for the most viscous meal (P < 0.01). Surprisingly, despite the fact that the initial meal viscosity varied 1000-fold, there was only a small delay in gastric emptying (P for trend < 0.05). The area under the curve for satiety increased with initial meal viscosity, whereas that for hunger decreased (P < 0.05). In conclusion, the viscosity of a meal in vivo can be measured noninvasively using EPI. The stomach responds to meal ingestion by rapid intragastric dilution, causing a reduction of meal viscosity, and gastric emptying is minimally delayed. However, increased viscosity is associated with more prolonged satiety.

Genetic refinement of the hereditary neuralgic amyotrophy (HNA) locus at chromosome 17q25

Hereditary neuralgic amyotrophy (HNA) is an autosomal dominant, recurrent focal neuropathy. HNA is characterised by episodes of painful brachial plexus neuropathy with muscle weakness and atrophy, as well as sensory disturbances. Single episodes are commonly preceded by non-specific infections, immunisations or parturition. Mild dysmorphic features and short stature are present in some HNA families, but absolute co-segregation with HNA has not been described. To refine the previously described HNA locus on chromosome 17q25, we performed a genetic linkage study in five HNA families with different geographic origins. Significant linkage was obtained with chromosome 17q24-q25 short tandem repeat (STR) markers in three HNA families and suggestive linkage was found in the other two HNA families. Analysis of the informative recombinations in affected individuals allowed us to reduce the HNA linkage interval to a candidate region of 3.5 cM.

A sequence-ready BAC/PAC contig and partial transcript map of approximately 1.5 Mb in human chromosome 17q25 comprising multiple disease genes

Hereditary neuralgic amyotrophy (HNA) is an autosomal dominant recurrent neuropathy mapped to a 4-cM interval on chromosome 17q25 between the short tandem repeat (STR) markers D17S1603 and D17S802. Chromosome 17q25 in general and the 4-cM HNA region in particular are also implicated in the pathogenesis of a number of tumors (tylosis with esophageal cancer, sporadic breast and ovarian tumors) and harbor a psoriasis susceptibility locus. Initial attempts to construct a yeast artificial chromosome contig failed. Therefore, we have now constructed a complete P1 artificial chromosome (PAC) and bacterial artificial chromosome (BAC) contig of the region flanked by the STR markers D17S1603 and D17S802. The contig contains 22 PAC and 64 BAC clones and covers a physical distance of approximately 1. 5 Mb. A total of 83 sequence-tagged site (STS) markers (10 known STSs and STRs, 56 STSs generated from clone end-fragments, 12 expressed sequence tags, and 5 known genes) were mapped on the contig, resulting in an extremely dense physical map with approximately 1 STS per 20 kb. This sequence-ready PAC and BAC contig will be pivotal for the positional cloning of the HNA gene as well as other disease genes mapping to this region.

A randomized trial of Evidence-based OutReach (EBOR): rationale and design

There is increasing interest in evaluating the methods used to implement the findings from medical research. This paper describes the Evidence-based OutReach (EBOR) trial, which is the first large randomized study in the United Kingdom that will evaluate the effectiveness and efficiency of educational outreach visits by trained pharmacists who are delivering messages derived from four evidence-based clinical practice guidelines. General practices form the unit of allocation and analysis. The study design addresses important factors that may influence the effectiveness of the intervention, such as the pharmacist who delivers the messages, the health authority in which practices are located, and the size of a practice.

Steroid injection for heel pain: evidence of short-term effectiveness. A randomized controlled trial

OBJECTIVES

To compare the effectiveness of a steroid injection (25 mg/ml prednisolone acetate) with a local anaesthetic control in the treatment of heel pain and to determine any advantage for patients' comfort of using a posterior tibial nerve block to anesthetize the heel prior to infiltration.

METHODS

A double-blind randomized controlled trial using a 2 x 2 design in a hospital-based rheumatology clinic. Subjects comprised 106 patients with heel pain referred by general practitioners and other rheumatologists working in Camden and Islington Health Authority.

MAIN OUTCOME MEASURES

heel pain reduction at 1, 3 and 6 months, and patient comfort at the time of injection. All outcomes were measured using a 10 cm visual analogue scale.

RESULTS

A statistically significant reduction in pain was detected at 1 month (P=0.02) in favour of steroid injection, but thereafter no differences could be detected. Patient comfort was not significantly affected by anaesthesia of the heel (P=0.5).

CONCLUSIONS

A steroid injection can provide relief from heel pain in the short term. There appears to be no increase in patient comfort from anaesthetizing the heel prior to infiltration.

Mesenchymal reprogramming of adult human epithelial differentiation

The objective of this study was to determine whether neonatal rat seminal vesicle mesenchyme (rSVM) can reprogram epithelial differentiation in a fully differentiated adult human bladder epithelium. For this purpose neonatal rSVM was isolated from newborn (0-day) Sprague-Dawley rats, and normal adult human bladder epithelium (hBLE) was isolated from radical cystoprostatectomy specimens to prepare rSVM+hBLE tissue recombinants in vitro. After overnight culture the tissue recombinants were grafted beneath the renal capsule of male athymic rodent hosts and allowed to grow in vivo for 6 months. As controls, rSVM and hBLE were grafted separately and allowed to grow for the same period. Tissue recombinants and control tissue grafts were harvested, and secretions were collected for biochemical studies. Tissues were fixed both for histologic as well as immunohistochemical staining. Neonatal rSVM induced normal adult human bladder urothelium to form glandular structures resembling prostate. The induced prostatic acini were filled with secretions that expressed human prostate-specific secretory proteins. These findings demonstrate that adult human urothelial cells retain a responsiveness to neonatal prostatic mesenchymal inductors. Change in urothelial histodifferentiation was associated with change in functional activity. The ability of the neonatal rat mesenchymal tissues to induce morphologic as well as biochemical changes in normal adult human urothelium provides a basis for human tissue engineering and organ reconstruction.

Insulin-like growth factor-I induces bcl-2 promoter through the transcription factor cAMP-response element-binding protein

Insulin-like growth factor-I (IGF-I) is known to prevent apoptosis induced by diverse stimuli. The present study examined the effect of IGF-I on the promoter activity of bcl-2, a gene with antiapoptotic function. A luciferase reporter driven by the promoter region of bcl-2 from -1640 to -1287 base pairs upstream of the translation start site containing a cAMP-response element was used in transient transfection assays. Treatment of PC12 cells with IGF-I enhanced the bcl-2 promoter activity by 2.3-fold, which was inhibited significantly (p < 0.01) by SB203580, an inhibitor of p38 mitogen-activated protein kinase (MAPK). Cotransfection of the bcl-2 promoter with MAPK kinase 6 and the beta isozyme of p38 MAPK resulted in 2-3-fold increase in the reporter activity. The dominant negative form of MAPKAP-K3, a downstream kinase activated by p38 MAPK, and the dominant negative form of cAMP-response element-binding protein, inhibited the reporter gene activation by IGF-I and p38beta MAPK significantly (p < 0.01). IGF-I increased the activity of p38beta MAPK introduced into the cells by adenoviral infection. Thus, we have characterized a novel signaling pathway (MAPK kinase 6/p38beta MAPK/MAPKAP-K3) that defines a transcriptional mechanism for the induction of the antiapoptotic protein Bcl-2 by IGF-I through the nuclear transcription factor cAMP-response element-binding protein in PC12 cells.

Contrast transcranial Doppler ultrasound in the detection of right-to-left shunts: comparison of different procedures and different contrast agents

BACKGROUND AND PURPOSE

Cardiac right-to-left shunts can be identified by transesophageal echocardiography (TEE) and by transcranial Doppler ultrasound (TCD) with the use of different contrast agents and different provocation procedures. Currently, data on an appropriate time window for the appearance of contrast bubbles in the TCD recording after the injection of the contrast medium and the comparison of different provocation maneuvers to increase right-to-left shunting are insufficient.

METHODS

Forty-six patients were investigated by both TEE and bilateral TCD of the middle cerebral artery. The following protocol with 6 injection modes was applied in a randomized way: (1) injection of 10 mL of agitated saline without Valsalva maneuver, (2) injection of 10 mL of agitated saline with Valsalva maneuver, (3) injection of 10 mL of a commercial galactose-based contrast agent (Echovist) without Valsalva maneuver, (4) injection of 10 mL of Echovist with Valsalva maneuver, (5) injection of 10 mL of Echovist with standardized Valsalva maneuver, and (6) injection of 10 mL of Echovist with coughing.

RESULTS

In 20 patients, a right-to-left shunt was demonstrated by TEE and contrast TCD (shunt-positive). Sixteen patients were negative in both investigations, no patient was positive on TEE and negative on TCD, and 10 patients were only positive on at least 1 TCD investigation but negative during TEE. The amount of microbubbles detected in the various tests decreased in the following order: Echovist and Valsalva maneuver, Echovist with coughing, Echovist and standardized Valsalva maneuver, saline with Valsalva maneuver, Echovist, and saline. With a time window of 20 to 25 seconds for the bubbles to appear in the TCD recording and with a sequence of first Echovist and Valsalva maneuver and then Echovist with coughing, all shunts were reliably identified with a specificity of 65% compared with TEE as the traditional gold standard. The time of first microbubble appearance was not helpful to distinguish between shunts detected on TEE and other shunts.

CONCLUSIONS

TCD performed twice with 2 provocation maneuvers using Echovist is a sensitive method to identify cardiac right-to-left shunts also identified by TEE.

Structure of the alpha-actinin rod: molecular basis for cross-linking of actin filaments

We have determined the crystal structure of the two central repeats in the alpha-actinin rod at 2.5 A resolution. The repeats are connected by a helical linker and form a symmetric, antiparallel dimer in which the repeats are aligned rather than staggered. Using this structure, which reveals the structural principle that governs the architecture of alpha-actinin, we have devised a plausible model of the entire alpha-actinin rod. The electrostatic properties explain how the two alpha-actinin subunits assemble in an antiparallel fashion, placing the actin-binding sites at both ends of the rod. This molecular architecture results in a protein that is able to form cross-links between actin filaments.

Systematic review of topical treatments for fungal infections of the skin and nails of the feet

OBJECTIVE

To identify and synthesise the evidence for efficacy and cost effectiveness of topical treatments for superficial fungal infections of the skin and nails of the feet.

DESIGN

Systematic review.

INTERVENTIONS

Topical treatments for superficial fungal infections.

MAIN OUTCOME MEASURES

Cure confirmed by culture and microscopy for skin and by culture for nails in patients with clinically diagnosed fungal infections.

RESULTS

Of 126 trials identified in 121 papers, 72 (57.1%) met the inclusion criteria. Placebo controlled trials yielded pooled relative risks of failure to cure skin infections: allylamines (0.30, 95% confidence interval 0.24 to 0.38); azoles (0.54, 0.42 to 0.68); undecenoic acid (0.28, 0. 11 to 0.74); and tolnaftate (0.46, 0.17 to 1.22). Although meta-analysis of 11 trials comparing allylamines and azoles showed a relative risk of failure to cure of 0.88 (0.78 to 0.99) in favour of allylamines, there was evidence of language bias. Seven reports in English favoured allylamines (0.79, 0.69 to 0.91), but four reports in foreign languages showed no difference between the two drugs (1. 01, 0.90 to 1.13). Neither trial of nail infections showed significant differences between alternative topical treatments.

CONCLUSIONS

Allylamines, azoles, and undecenoic acid were efficacious in placebo controlled trials. There are sufficient comparative trials to judge relative efficacy only between allylamines and azoles. Allylamines cure slightly more infections than azoles but are much more expensive than azoles. The most cost effective strategy is first to treat with azoles or undecenoic acid and to use allylamines only if that fails.

Autosomal dominant burning feet syndrome

Familial burning feet syndrome inherited as an autosomal dominant trait has been described in only one family. Due to an associated sensory neuropathy the autosomal dominant burning feet syndrome was suggested to represent a variant form of hereditary sensory and autonomic neuropathy type I (HSAN I). Clinical, histopathological, and molecular genetic studies were performed in a large German kindred with autosomal dominant burning feet syndrome. The autosomal dominant burning feet syndrome was associated with a neuropathy predominantly affecting small unmyelinated nerve fibres. Linkage to the HSAN I locus on chromosome 9q22 and to the Charcot-Marie-Tooth disease type 2B (CMT 2B) locus on chromosome 3q13-q22 was excluded. The autosomal dominant burning feet syndrome is neither allelic to HSAN I nor to CMT 2B and thus represents a distinct genetic entity.