Optical coherence tomography for presurgical delineation of basal cell carcinomas on the face-A comparison with histopathology.

BACKGROUND: To minimize the risk of incomplete excision of basal cell carcinomas (BCC) the macroscopic tumor margins should be adequately defined. Optical coherence tomography (OCT) is a non-invasive imaging tool that can provide structural and vascular information about skin cancer lesions. The study objective was to compare the presurgical delineation of facial BCC by clinical examination, histopathology, and OCT imaging in tumors undergoing full excision. METHODS: Ten patients with BCC lesions on the face were examined clinically, with OCT and histopathology at 3-mm intervals, from the clinical lesion border and beyond the resection line. The OCT scans were evaluated blinded and a delineation estimate of each BCC lesion was made. The results were compared to the clinical and histopathologic results. RESULTS: OCT evaluations and histopathology were in agreement in 86.6% of the collected data points. In three cases the OCT scans estimated a reduction of the tumor size compared to the clinical tumor border set by the surgeon. CONCLUSION: The results of this study support the notion that OCT can have a role in the clinical daily practice by aiding clinicians in delineating BCC lesions before surgery.

Patients with Lemierre syndrome have a high risk of new thromboembolic complications, clinical sequelae and death: an analysis of 712 cases.

BACKGROUND: Lemierre syndrome is characterized by head/neck vein thrombosis and septic embolism usually complicating an acute oropharyngeal bacterial infection in adolescents and young adults. We described the course of Lemierre syndrome in the contemporary era. METHODS: In our individual-level analysis of 712 patients (2000-2017), we included cases described as Lemierre syndrome if these criteria were met: (i) primary site of bacterial infection in the head/neck; (ii) objectively confirmed local thrombotic complications or septic embolism. The study outcomes were new or recurrent venous thromboembolism or peripheral septic lesions, major bleeding, all-cause death and clinical sequelae. RESULTS: The median age was 21 (Q1-Q3: 17-33) years, and 295 (41%) were female. At diagnosis, acute thrombosis of head/neck veins was detected in 597 (84%) patients, septic embolism in 582 (82%) and both in 468 (80%). After diagnosis and during in-hospital follow-up, new venous thromboembolism occurred in 34 (5.2%, 95% CI 3.8-7.2%) patients, new peripheral septic lesions became evident in 76 (11.7%; 9.4-14.3%). The rate of either was lower in patients who received anticoagulation (OR: 0.59; 0.36-0.94), higher in those with initial intracranial involvement (OR: 2.35; 1.45-3.80). Major bleeding occurred in 19 patients (2.9%; 1.9-4.5%), and 26 died (4.0%; 2.7-5.8%). Clinical sequelae were reported in 65 (10.4%, 8.2-13.0%) individuals, often consisting of cranial nerve palsy (n = 24) and orthopaedic limitations (n = 19). CONCLUSIONS: Patients with Lemierre syndrome were characterized by a substantial risk of new thromboembolic complications and death. This risk was higher in the presence of initial intracranial involvement. One-tenth of survivors suffered major clinical sequelae.

21-hydroxylase autoantibodies are more prevalent in Turner syndrome but without an association to the autoimmune polyendocrine syndrome type I.

Turner syndrome (TS) is associated with an increased frequency of autoimmunity. Frequently observed autoimmune diseases in TS are also seen in the autoimmune polyendocrine syndrome type I (APS I), of which Addison disease is a key component. An overlapping antibody profile between TS and APS I could be considered. The aim of this work was to study women with TS regarding 21-hydroxylase (21-OH) antibodies and interferon omega (IFN-ω) antibodies, a highly specific marker for APS I, to determine if there are immunological overlaps between TS and APS I. Blood samples from 141 TS were assayed for 21-OH antibodies and IFN-ω antibodies using in-vitro-transcribed and translated autoantigen. Indices with a cut-off point of 57 and 200 for 21-OH antibody and IFN-ω antibody were used as reference. The median age of TS was 31·6 years (range = 11·2-62·2). Positive indices of 21-OH antibodies were present in six TS (4%), with a mean of 144·8 (range = 60-535). None had apparent adrenal insufficiency. There was no age difference comparing 21-OH antibody-positive TS (median age = 33·9 years, range = 17·7-44·7) and 21-OH antibody-negative TS (median age = 31·6 years, range = 11·2-62·2) (P = 0·8). No TS was positive for IFN-ω antibodies (mean = 42·4, range = -435-191). No overlapping autoimmune profile between TS and APS I was found. Autoimmunity against 21-OH among TS patients was more prevalent than previously identified, suggesting an increased risk of adrenal failure in TS. However, whether adrenal impairment will develop remains unknown.

Observation method identifies that a lack of canonical babbling can indicate future speech and language problems.

AIM: We investigated how accurate observations of canonical babbling (CB) were and explored predictive babbling measures in children with and without medical diagnoses of conditions that can lead to speech and language problems. METHODS: From 2012 to 2014 this Stockholm-based study recruited 38 children aged nine months to 21 months with medical diagnoses and 30 children aged 10 months without diagnoses and included 21 previously studied 12-month-old children without medical diagnoses. CB and consonant sound production were directly observed by video recording natural play with a caregiver. The percentage of CB was calculated from each recording, and a validated observation form was used. How accurately the children with and without CB were classified was investigated with sensitivity and specificity. The groups were compared using predictive babbling variables. RESULTS: The observation method identified children with and without CB well, with a specificity of 0.89 and sensitivity of 0.93, respectively. Children with predictive babbling measures were identified in the clinical group (specificity 0.93-0.97), and a lack of these measures indicated a risk of being in the clinical group (odds ratios > 10). The sensitivity was low (0.32-0.42). CONCLUSION: Observation effectively identified a lack of CB and supported the importance of assessing babbling measures.

Glenohumeral and scapulothoracic strength impairments exists in patients with subacromial impingement, but these are not reflected in the shoulder pain and disability index.

BACKGROUND: Pain and loss of function are cardinal symptoms associated with Subacromial impingement syndrome (SIS), while the presence and magnitude of deficits in strength and range of motion (ROM) are largely undescribed in non-athletic patients with SIS. Moreover, the relevance of impairments in strength and ROM to patient-reported shoulder function is not well described, even though testing of strength is recommended in clinical guidelines. The purpose of this study was, first, to investigate impairments in glenohumeral and scapulothoracic strength and in abduction and internal rotation ROM in patients with SIS. Secondly, to investigate the influence of these impairments on patient-reported shoulder function. METHODS: Cross-sectional study based on a consecutive cohort of 157 patients referred to specialist examination and diagnosed with shoulder impingement (SIS) using predefined validated diagnostic criteria. Prior to specialist examination, questionnaires regarding shoulder function (Shoulder Pain And Disability Index, SPADI) demographics and kinesiophobia (TSK-11) were collected, and shoulder strength and ROM was measured by trained testers, with the patient reporting pain levels during testing and for the last week. Impairments in strength (abduction, external-rotation, (protraction and horizontal-extension) and ROM (abduction and internal rotation) were investigated in patients with unilateral shoulder pain, using one-sample t-tests. SPADI total score (SPADI) and SPADI function score (SPADI-F), were chosen as dependent variables in multiple regressions to investigate the influence of impairments on patient-reported shoulder function. Independent variables of interest were; strength in abduction and external rotation, abduction ROM, pain-during-tests, pain-last-week and kinesiophobia. RESULTS: Significant impairments were found for all impairment tests, but most pronounced for glenohumeral strength and abduction ROM (29-33% deficits), and less for scapulothoracic strength and internal rotation ROM (8-18% deficits). Pain variables influenced SPADI and SPADI-F score to a high degree (R2 = 23.4-31.6%, p < 0.001), while strength and ROM did not. CONCLUSION: Substantial strength and ROM impairments were found in patients with SIS. Only pain significantly influenced patient-reported function, while impairments did not. As SPADI score does not reflect the substantial strength and ROM impairments in external rotation and abduction observed in patients with SIS, supplemental assessment of these impairments seems important.

Autoimmune risk variants in ERAP2 are associated with gene-expression levels in thymus.

Genetic polymorphisms in the endoplasmic reticulum aminopeptidase (ERAP)1 and ERAP2 genes have been associated with several autoimmune diseases (AIDs) at a genome-wide significance level. In this study, we performed a cis expression quantitative trait locus (eQTL) screen to investigate whether seven fine-mapped AID single-nucleotide polymorphisms (SNPs) in the ERAP-region influence the gene-expression levels of ERAP1 and ERAP2 in thymus. After quality control, we identified six significant eQTLs. We further assessed the peak eQTL signals, and both genes showed highly significant and independent thymic eQTL signals (P=2.16 × 10-15 and P=8.22 × 10-23, respectively). Interestingly, the peak eQTL signal overlapped with the AID risk loci in ERAP2 (r2>0.94), but were distinct in ERAP1 (r2<0.4). Finally, among the SNPs showing the most significant eQTL associations with ERAP2 (P<3.4 × 10-20), six were located within transcription factor motifs in an enhancer region in thymus. Our study therefore reveals the fine-mapped AID risk variants that act as eQTLs with ERAP2 in thymus, and highlights the potential causal regulatory variants.

Genomic signature of successful colonization of Eurasia by the allopolyploid shepherd's purse (Capsella bursa-pastoris).

Polyploidization is a dominant feature of flowering plant evolution. However, detailed genomic analyses of the interpopulation diversification of polyploids following genome duplication are still in their infancy, mainly because of methodological limits, both in terms of sequencing and computational analyses. The shepherd's purse (Capsella bursa-pastoris) is one of the most common weed species in the world. It is highly self-fertilizing, and recent genomic data indicate that it is an allopolyploid, resulting from hybridization between the ancestors of the diploid species Capsella grandiflora and Capsella orientalis. Here, we investigated the genomic diversity of C. bursa-pastoris, its population structure and demographic history, following allopolyploidization in Eurasia. To that end, we genotyped 261 C. bursa-pastoris accessions spread across Europe, the Middle East and Asia, using genotyping-by-sequencing, leading to a total of 4274 SNPs after quality control. Bayesian clustering analyses revealed three distinct genetic clusters in Eurasia: one cluster grouping samples from Western Europe and Southeastern Siberia, the second one centred on Eastern Asia and the third one in the Middle East. Approximate Bayesian computation (ABC) supported the hypothesis that C. bursa-pastoris underwent a typical colonization history involving low gene flow among colonizing populations, likely starting from the Middle East towards Europe and followed by successive human-mediated expansions into Eastern Asia. Altogether, these findings bring new insights into the recent multistage colonization history of the allotetraploid C. bursa-pastoris and highlight ABC and genotyping-by-sequencing data as promising but still challenging tools to infer demographic histories of selfing allopolyploids.

Invasive Fusobacterium necrophorum infections and Lemièrre's syndrome: the role of thrombophilia and EBV.

The purpose of this investigation was to describe the clinical spectrum of invasive Fusobacterium necrophorum infections and Lemièrre's syndrome, to examine the role of underlying thrombophilia and concomitant mononucleosis in Lemièrre's syndrome, and to describe thromboembolic complications. Patients with invasive F. necrophorum infections were identified either prospectively or retrospectively through the regional database of clinical microbiology from 2000 to 2015. Patient records were reviewed and blood samples from patients with Lemièrre's syndrome were collected for Epstein-Barr virus (EBV) serology and screening for thrombophilia. Of the 65 patients included, 33 had Lemièrre's syndrome. Of the remaining 32 patients, other infections of the respiratory tract and abdominal or urogenital infections were most common. Patients with Lemièrre's syndrome or other tonsillar infections were younger than patients from the other groups. For Lemièrre's syndrome, the 26 patients with severe sepsis on admittance had longer duration of symptoms. Three of five patients who developed distant manifestations had more than 14 days of symptoms. Jugular vein thrombosis was verified in 14 patients, two of whom developed serious complications. Three of 26 patients tested had factor V Leiden mutation, corresponding to the background prevalence. One of 22 patients tested had a concomitant EBV infection. This study confirms earlier studies of the clinical spectrum caused by F. necrophorum. For Lemièrre's syndrome, the study adds to the knowledge on thromboembolic outcome, demonstrating that jugular vein thrombosis may cause severe complications. The time to treatment seems to be important for the risk of severe disease. In this study, concomitant EBV infection or underlying thrombophilia was uncommon.

Invasive infections with Fusobacterium necrophorum including Lemierre's syndrome: an 8-year Swedish nationwide retrospective study.

OBJECTIVES: We aimed to evaluate the nationwide incidence and a potential increase in invasive infections with Fusobacterium necrophorum. Secondly, we aimed to describe epidemiology, clinical characteristics and outcomes for the different presentations: Lemierre's syndrome (LS), invasive head and neck-infection without LS and invasive non-head and neck-infection. METHODS: A retrospective multicentric population-based study of all invasive infections with F. necrophorum diagnosed in Sweden from 2010 to 2017 with 6 months of follow-up was performed through reviews of medical records. Invasive infections were defined and identified by a positive blood culture or sequencing of 16S rDNA, targeted PCR or culture from normally sterile sites. Incidence calculations were performed, including comparisons between 2010-13 and 2014-17, age groups and clinical presentations. Patient and infection characteristics, treatment and clinical outcomes were analysed. RESULTS: Invasive infections with F. necrophorum were diagnosed in 300 cases in Sweden 2010-17. The incidence increased from 2.9 to 5.0 cases/million/year from 2010-13 to 2014-17 (p 0.001). A total of 104/300 (35%) patients developed LS, 102/300 (34%) invasive head and neck infection without LS and 94/300 (31%) invasive non-head and neck infection. The median age was 20, 25 and 64 years, respectively. Among patients with LS 72/96 (75%) had thrombocytopenia on admission, 86/104 (83%) had sepsis, 19/104 (18%) developed septic shock and 45/104 (43%) needed intensive care. 30-day mortality in LS was 2/104 (2%). CONCLUSION: We describe an increased incidence of invasive infections with F. necrophorum in Sweden and highlight its full spectrum of invasive clinical presentations. LS, in particular, causes considerable morbidity in young and previously healthy patients.

Brain malformation in single median maxillary central incisor.

Clinical and radiographic examinations and MR scan of a 12-year-old girl with SMMCI (single median maxillary central incisor) showed impaired growth and a midline defect involving the central incisor, cranium and the midline structures in the brain, falx cerebri and pituitary gland. She had a severe growth hormone deficiency but no other pituitary hormone deficiencies. She was treated with growth hormone and followed during a four-year period with successful gain in body height and sexual maturation. This study focuses on the developmental association between the involved structures and provides guidelines for early diagnostics.

Spinal kinematics in horses with induced back pain.

Back problems are important contributors to poor performance in sport horses. It has been shown that kinematic analysis can differentiate horses with back problems from asymptomatic horses. The underlying mechanism can, however, only be identified in a uniform, experimental setting. Our aim was to determine if induction of back pain in a well-defined site would result in a consistent change in back movement. Back kinematics were recorded at a walk and trot on a treadmill. Unilateral back pain was then induced by injecting lactic acid into the left longissimus dorsi muscle. Additional measurements were done subsequent to the injections. Data were captured during steady state locomotion at 240 Hz using an infrared-based gait analysis system. After the injections, the caudal thoracic back was more extended at both gaits. The back was also bent more to the left at both gaits. However, at the walk, there was a reversed pattern after a week with bending of the back to the unaffected side. Horses with identical back injuries appear to show similar changes in their back kinematics, as compared to the asymptomatic condition. Unilateral back pain seems to result in an increased extension of the back, as well as compensatory lateral movements. Back movements are complex and subtle, and changes are difficult to detect with the human eye. Present-day gait analysis systems can identify changes in the back movement, and knowledge of the relationship between such changes and the site of injury will be of help in better localising and diagnosing disorders of the equine back.

Gut microbiota composition during a 12-week intervention with delayed-release dimethyl fumarate in multiple sclerosis - a pilot trial.

INTRODUCTION: Patients with multiple sclerosis may have a distinct gut microbiota profile. Delayed-release dimethyl fumarate is an orally administered drug for relapsing-remitting multiple sclerosis, which has been associated with gastrointestinal side-effects in some patients. OBJECTIVES: The purpose of this study was to determine if dimethyl fumarate alters the abundance and diversity of commensal gut bacteria, and if these changes are associated with gastrointestinal side-effects. METHODS: Thirty-six patients with relapsing-remitting multiple sclerosis received either dimethyl fumarate (n = 27) or an injectable multiple sclerosis disease-modifying therapy (glatiramer acetate or interferons, n = 9) for 12 weeks. Stool samples were collected at baseline, two and 12 weeks. We included 165 healthy individuals as controls. RESULTS: At baseline, 16 microbial genera were altered in multiple sclerosis patients compared with healthy controls. In the dimethyl fumarate-treated patients (n = 21) we observed a trend of reduced Actinobacteria (p = 0.03, QFDR = 0.24) at two weeks, mainly driven by Bifidobacterium (p = 0.06, QFDR = 0.69). At 12 weeks, we observed an increased abundance of Firmicutes (p = 0.02, QFDR = 0.09), mostly driven by Faecalibacterium (p = 0.01, QFDR = 0.48). CONCLUSIONS: This pilot study did not detect a major effect of dimethyl fumarate on the gut microbiota composition, but we observed a trend towards normalization of the low abundance of butyrate-producing Faecalibacterium after 12 weeks treatment. The study was underpowered to link microbiota to gastrointestinal symptoms.

Rifaximin alters gut microbiota profile, but does not affect systemic inflammation - a randomized controlled trial in common variable immunodeficiency.

Common variable immunodeficiency (CVID) patients have reduced gut microbial diversity compared to healthy controls. The reduced diversity is associated with gut leakage, increased systemic inflammation and ten "key" bacteria that capture the gut dysbiosis (dysbiosis index) in CVID. Rifaximin is a broad-spectrum non-absorbable antibiotic known to reduce gut leakage (lipopolysaccharides, LPS) in liver disease. In this study, we explored as a 'proof of concept' that altering gut microbial composition could reduce systemic inflammation, using CVID as a disease model. Forty adult CVID patients were randomized, (1:1) to twice-daily oral rifaximin 550 mg versus no treatment for 2 weeks in an open-label, single-centre study. Primary endpoints were reduction in plasma/serum levels of soluble (s) CD14, sCD25, sCD163, neopterin, CRP, TNF, LPS and selected cytokines measured at 0, 2 and 8 weeks. Secondary endpoint was changes in intra-individual bacterial diversity in stool samples. Rifaximin-use did not significantly change any of the inflammation or gut leakage markers, but decreased gut microbial diversity compared with no treatment (p = 0.002). Importantly, the gut bacteria in the CVID dysbiosis index were not changed by rifaximin. The results suggest that modulating gut microbiota by rifaximin is not the chosen intervention to affect systemic inflammation, at least not in CVID.

A comparative analysis of kinetic models of erythrocyte glycolysis.

Since the 1970s, with Heinrich as a pioneer in the field, numerous kinetic models of erythrocyte glycolysis have been constructed. A functional comparison of eight of these models indicates that the production of ATP and GSH in the red blood cell is largely controlled by the demand reactions. The rate characteristics for the supply and demand blocks indicate a good homeostatic control of ATP and GSH concentrations at different work loads for the pathway, while the production rates of ATP and GSH can be adjusted as needed by the demand reactions.

Identification of an essential Schizosaccharomyces pombe RNA homologous to the 7SL component of signal recognition particle.

We have cloned the gene encoding a novel small cytoplasmic RNA from the fission yeast Schizosaccharomyces pombe. Four lines of evidence support the idea that this RNA is a homolog of the 7SL RNA component of mammalian signal recognition particle (SRP), which targets presecretory proteins to the endoplasmic reticulum membrane. First, it shares limited but significant primary sequence homology with previously identified 7SL RNAs and can be folded into a similar secondary structure. Second, it possesses the 5' triphosphate characteristic of unprocessed RNA polymerase III transcripts, and moreover, it is the only fission yeast RNA in this size range with such a terminus. Third, its behavior in cell fractionation experiments suggests that it is part of a small ribonucleoprotein which forms salt-labile contacts with larger structures. Fourth, the particle containing S. pombe 7SL RNA resembles mammalian SRP in both size (11S) and affinity for DEAE-Sepharose. Disruption of the single-copy gene, designated slr1+, reveals that the RNA is indispensable for growth in fission yeast. This result is not surprising, since secretion is an essential cellular process.

Deregulated expression of E2F family members induces S-phase entry and overcomes p16INK4A-mediated growth suppression.

The E2F family of transcription factors regulate genes, whose products are essential for progression through the mammalian cell cycle. The transcriptional activity of the E2Fs is inhibited through the specific binding of the retinoblastoma protein, pRB, and the pRB homologs p107 and p130 to their transactivation domains. Seven members of the E2F transcription factor family have been isolated so far, and we were interested in investigating the possible contribution of the various E2Fs to cell cycle control. By presenting the results of the generation of cell lines with tetracycline-controlled expression of E2F-1 and E2F-4 and microinjection of expression plasmids for all members of the E2F family, we demonstrate here that the pRB-associated ED2Fs (E2F-1, E2F-2, and E2F-3) all induce S phase in quiescent rate fibroblasts when expressed alone. In contrast, the p107/p130-associated E2Fs require the coexpression of the heterodimeric partner DP-1 to promote S-phase entry and accelerate G1 progression. Furthermore, the pRB-associated E2Fs were all able to overcome a G1 arrest mediated by the p16INK4 tumor suppressor protein, and E2F-1 was shown to override a G1 block mediated by a neutralizing antibody to cyclin D1. The p16INK4-induced G1 arrest was not affected by expression of E2F-4, E2F-5, or DP-1 alone, but simulataneous expression of E2F-4 and DP-1 could overcome this block. Our results demonstrate that the generation of E2F activity is rate limiting for G1 progession, is sufficient to induce S-phase entry, and overcomes a p16-mediated G1 block, and since E12F-1, E2F-2, and E2F-3 are associated with pRB, they are the most likely downstream effectors in the p126-cyclin D-pRB pathway. Furthermore, our date suggest that the two subsets of E2Fs are regulated by distinct mechanisms and/or that they have distinct functions in cell cycle control. Since E2F-4 and E2F-5 cannot promote S-phase entry by themselves, our results may provide an explanation for the apparent lack of aberrations in p107 or p130 in human cancer.

Guide to active vaccine safety surveillance: Report of CIOMS working group on vaccine safety - executive summary.

In 2013, the Council for International Organizations of Medical Sciences (CIOMS) created a Working Group on Vaccine Safety (WG) to address unmet needs in the area of vaccine pharmacovigilance. Generating reliable data about specific vaccine safety concerns is becoming a priority due to recent progress in the development and deployment of new vaccines of global importance, as well as novel vaccines targeting diseases specifically endemic to many resource-limited countries (RLCs), e.g. malaria, dengue. The WG created a Guide to Active Vaccine Safety Surveillance (AVSS) to assist national regulatory authorities and national immunization program officers in RLCs in determining the best course of action with regards to non-routine pharmacovigilance activities, when confronted with a launch of a new vaccine or a vaccine that is new to their country. Here we summarize the results of the WG, further detailed in the Guide, which for the first time provides a structured approach to identifying and analyzing specific vaccines safety knowledge gaps, while considering all available sources of information, in order to determine whether AVSS is an appropriate solution. If AVSS is confirmed as being the appropriate tool, the Guide provides additional essential information on AVSS, a detailed overview of common types of AVSS and practical implementation considerations. It also provides a framework for a well-constructed and informative AVSS when needed, thus aiming to ensure the best possible safety of immunization in this new landscape.

HLA haplotypes in primary sclerosing cholangitis patients of admixed and non-European ancestry.

Primary sclerosing cholangitis (PSC) is strongly associated with several human leukocyte antigen (HLA) haplotypes. Due to extensive linkage disequilibrium and multiple polymorphic candidate genes in the HLA complex, identifying the alleles responsible for these associations has proven difficult. We aimed to evaluate whether studying populations of admixed or non-European descent could help in defining the causative HLA alleles. When assessing haplotypes carrying HLA-DRB1*13:01 (hypothesized to specifically increase the susceptibility to chronic cholangitis), we observed that every haplotype in the Scandinavian PSC population carried HLA-DQB1*06:03. In contrast, only 65% of HLA-DRB1*13:01 haplotypes in an admixed/non-European PSC population carried this allele, suggesting that further assessments of the PSC-associated haplotype HLA-DRB1*13:01-DQA1*01:03-DQB1*06:03 in admixed or multi-ethnic populations could aid in identifying the causative allele.

Factors intrinsic to the neuron can induce and maintain its ability to promote axonal outgrowth: a role for BCL2?

The adult CNS provides a poor environment for axonal growth and regeneration. The question of to what extent the loss of axonal growth occurring as the brain matures is dependent on factors intrinsic or extrinsic to the growing neuron is still unanswered. Examination of axonal growth from neural transplants provides insight into the roles of growth factors, inhibitory molecules, growth-promoting substrates and the differences between CNS and PNS environments in the regulation of neurite extension. The data that imply a role for BCL2 and related molecules in such processes are reviewed in this article, which analyzes the factors intrinsic to the neuron that control its capacity for axonal growth.