Structure-activity relationship read-across and transcriptomics for branched carboxylic acids.

The purpose of this study was to use chemical similarity evaluations, transcriptional profiling, in vitro toxicokinetic data, and physiologically based pharmacokinetic (PBPK) models to support read-across for a series of branched carboxylic acids using valproic acid (VPA), a known developmental toxicant, as a comparator. The chemicals included 2-propylpentanoic acid (VPA), 2-ethylbutanoic acid, 2-ethylhexanoic acid (EHA), 2-methylnonanoic acid, 2-hexyldecanoic acid, 2-propylnonanoic acid (PNA), dipentyl acetic acid or 2-pentylheptanoic acid, octanoic acid (a straight chain alkyl acid), and 2-ethylhexanol. Transcriptomics was evaluated in 4 cell types (A549, HepG2, MCF7, and iCell cardiomyocytes) 6 h after exposure to 3 concentrations of the compounds, using the L1000 platform. The transcriptional profiling data indicate that 2- or 3-carbon alkyl substituents at the alpha position of the carboxylic acid (EHA and PNA) elicit a transcriptional profile similar to the one elicited by VPA. The transcriptional profile is different for the other chemicals tested, which provides support for limiting read-across from VPA to much shorter and longer acids. Molecular docking models for histone deacetylases, the putative target of VPA, provide a possible mechanistic explanation for the activity cliff elucidated by transcriptomics. In vitro toxicokinetic data were utilized in a PBPK model to estimate internal dosimetry. The PBPK modeling data show that as the branched chain increases, predicted plasma Cmax decreases. This work demonstrates how transcriptomics and other mode of action-based methods can improve read-across.

Feasibility analysis of CT-guided thermal ablation of multiple pulmonary nodules combined with intraoperative biopsy.

Purpose: To analyze the safety and feasibility of computed tomography (CT)-guided thermal ablation of multiple pulmonary nodules combined with intraoperative biopsy. Methods: The data of 431 patients with 540 lung nodules undergoing CT-guided biopsy or ablation were retrospectively analyzed. Biopsy-only group (A): 107 patients (107 lesions) received CT-guided percutaneous lung biopsy only; Ablation-only group (B): 117 cases (117 lesions) only received CT-guided thermal ablation; Single focal ablation combined with biopsy group (C): 103 patients (103 lesions) received CT-guided thermal ablation combined with intraoperative immediate biopsy; Multifocal ablation combined with biopsy group (D): 104 patients (213 lesions) received CT-guided thermal ablation combined with intraoperative biopsy. The success rate of this technique was calculated, the complications were recorded, and the positive rate of pathological diagnosis of the specimens was evaluated (the tissue specimens could be confirmed as positive by pathological diagnosis). Results: All 431 patients with pulmonary nodules successfully completed the operation, and the technical success rate was 100% (431/431). In group A, hemoptysis occurred in seven cases after operation, while no hemoptysis was observed in the other groups. Pneumothorax occurred in 8 cases in group A, 14 cases in group B, 11 cases in group C, and 13 cases in group D. Hydrothorax occurred in 4 cases in group A, 7 cases in group B, 5 cases in group C and 9 cases in group D, and there were no significant differences between the groups. The positive rate of pathological diagnosis was 84.1% (90/107) in group A, 81.5% (84/103) in group C, and 82.6% (176/213) in group D, and there was no significant difference among the groups (P > 0.05). A total of 15 cases in group C and 23 cases in group D underwent gene testing and analysis, and the biopsy tissue samples all met quality control standards. Conclusion: CT-guided thermal ablation of multiple pulmonary nodules combined with intraoperative biopsy does not prolong the length of hospital stay or increase the risk of postoperative complications. It can meet the requirements of clinical, pathological and genetic testing, and is safe and reliable.

Exopolysaccharides produced by Pediococcus acidilactici MT41-11 isolated from camel milk: Structural characteristics and bioactive properties.

In this study, the chemical structure and bioactive properties of the EPS of Pediococcus acidilactici MT41-11 isolated from camel milk were investigated. Two polysaccharide fractions (EPS-1, EPS-2) with molecular weights about 69.0 kDa were obtained, which were purified using DEAE-Sepharose and Sephadex G-100 chromatography. Based on monosaccharide composition, FT-IR, and 1D, 2D NMR spectra, concluded that EPS-1 had a backbone composed of →2)-α-d-Manp-(1→, →3)-α-d-Manp-(1→ and with branches containing α-d-Manp-(1→, EPS-2 had a backbone composed of →6)-ß-d-Glcp-(1→, and with branches containing →2)-α-l-Fucp-(1→, →3)-α-d-Glcp-(1→, →2)-α-d-Glcp-(1→, ß-d-Glcp-(1→, and α-d-Glcp-(1→. Remarkably, in vitro assays showed that EPS possessed multiple bioactive properties, including stimulating Lactobacillus growth and a high DPPH free radical scavenging activity. Also, it has a good ability to anti-biofilms. Overall, the analysis of all data showed EPS from P. acidilactici MT41-11 can be used as anti-oxidant, anti-biofilm agent, and also as a potential candidate prebiotic for health food or medicine industry.

Chemotherapy combined with intermittent microwave ablation in the treatment of oligometastatic non-small cell lung cancer.

PURPOSE: To observe the role of chemotherapy combined with microwave ablation in the treatment of oligometastatic non-small cell lung cancer (NSCLC). METHODS: 68 oligometastatic NSCLC patients were enrolled in this comparative study and randomly received chemotherapy with intermittent CT guided microwave ablation or chemotherapy only. The efficacy and the adverse effects were evaluated at 1, 3, and 6 months after treatment. RESULTS: Patients in the experimental group received microwave ablation after chemotherapy (n=s34), complete remission (CR) was found in 8 cases (23.53%), partial remission (PR) in 16 cases (47.06%), and the total effective rate (CR+PR) was 70.59%. Microwave ablation with concurrent chemotherapy was performed in patients of the control group (n=33) and there were 0 patients of CR (0%), 12 patients of PR (36.36%), and the total effective rate (CR+PR) was 36.36% (χ2=7.890, p<0.01). The score of Karnofski performance status (KPS) in the experimental group was significantly higher (p<0.05). The median progression-free survival (PFS) in the control group and the experimental group was 3.6±0.2 months and 5.4±0.1 months (χ2=42.731, p<0.01). The incidence of pneumothorax and bloody sputum in the experimental group was higher than that in the control group (χ2=6.031, p<0.05). However, no evident differences were found regarding other common complications of microwave ablation and chemotherapy. CONCLUSION: Chemotherapy combined with intermittent microwave ablation is superior to chemotherapy alone in improving the disease control rate and the quality of life of patients, as well as prolonging the PFS of patients.

Comparison of serum tumor markers combined with dual-source CT in the diagnosis of lung cancer.

BACKGROUND: The purpose of this study is to explore the clinical value of serum tumor markers combined with dual-source CT scanning in the diagnosis of lung cancer. METHODS: 102 patients with lung cancer (malignant tumor group), 50 patients with benign lesions (benign control group) and 50 healthy patients (normal control group) were selected as the research objects. The levels of serum carcinoembryonic antigen (CEA), cytokeratin 19 fragment antigen 21-1 (CYFRA21-1) and gastrin releasing peptide precursor 31-98 (Pro-GRP31-98) were detected using the electrochemiluminescence and enzyme-linked immunoassay in three groups of people. Simultaneously, Siemens' second-generation dual-source CT is used to scan the lungs of patients with lung cancer and benign lesions. Retrospective statistical analysis is utilized to explore the clinical value of serum tumor markers combined with dualsource CT examination in the diagnosis of lung cancer. RESULTS: The levels of serum CEA, CYFRA21-1 and Pro-GRP31-98 in lung cancer patients were significantly higher than those in the benign control group and normal control group, and the difference was statistically significant (P<0.01). There was no statistical difference between the benign control group and the normal control group (P>0.05). The levels of serum CEA, CYFRA21-1, Pro-GRP31-98 had no significant correlation with the age, sex, and tumor site of lung cancer patients (P>0.05). However, the levels of serum CEA, CYFRA21-1, Pro-GRP31-98 have an obvious correlation with tumor size, clinical stage, histological type, combined pleural effusion, recurrence and metastasis after treatment (P<0.05). CT scans of 102 lung cancer patients showed 35 cases of central type, 67 cases of peripheral type, 71 cases with tumor diameter >5cm, 31 cases of ≤5cm and 67 cases of lymph node metastasis. The sensitivities of CEA, CYFRA21-1, Pro-GRP31-98, and dual-source CT in the diagnosis of lung cancer were 64.70%, 60.11%, 56.86% and 77.45%, and the accuracy was 75.00%, 72.37%, 69.74% and 82.89%, respectively. Compared with a single examination, the sensitivity and accuracy of combined examination for the diagnosis of lung cancer were significantly improved, which were 95.10% and 92.76%, respectively. CONCLUSIONS: Joint examinations can effectively improve the rate of lung cancer diagnosis.

A comparison of classical and 21st century genotoxicity tools: A proof of concept study of 18 chemicals comparing in vitro micronucleus, ToxTracker and genomics-based methods (TGx-DDI, whole genome clustering and connectivity mapping).

A key step in the risk assessment process of a substance is the assessment of its genotoxic potential. Irrespective of the industry involved, current approaches rely on combinations of two or three in vitro tests and while highly sensitive, their specificity is thought to be limited. A refined in vitro genotoxicity testing strategy with improved predictive capacity would be beneficial and "3R" friendly as it helps to avoid unnecessary in vivo follow-up testing. Here, we describe a proof of concept study evaluating a balanced set of compounds that have in vivo negative or positive outcomes, but variable in vitro data, to determine if we could differentiate between direct and indirect acting genotoxicants. Compounds were examined in TK6 cells using an approach in which the same sample was used to evaluate both early genomic markers (Affymetrix analysis 4 hr post treatment), and the genotoxic outcome (micronuclei [MN] after 24 hr). The resulting genomic data was then analyzed using the TGx-DDI biomarker, Connectivity mapping and whole genome clustering. Chemicals were also tested in the ToxTracker assay, which uses six different biomarker genes. None of the methods correctly differentiated all direct from indirect acting genotoxicants when used alone, however, the ToxTracker assay, TGx-DDI biomarker and whole genome approaches provided high predictive capacity when used in combination with the MN assay (1/18, 2/18, 1/18 missed calls). Ultimately, a "fit for purpose" combination will depend on the specific tools available to the end user, as well as considerations of the unique benefits of the individual assays.

LncRNA CYTOR promotes pancreatic cancer cell proliferation and migration by sponging miR-205-5p.

BACKGROUND/AIMS: Studies have found that LncRNA CYTOR is an important regulator of cancer. However, the function of lncRNA CYTOR in pancreatic cancer (PC) is unclear. This study amid to explore the regulation of lncRNA CYTOR in PC. METHODS: The expression of CYTOR and miR-205-5p in PC was detected by RT-qPCR. CCK-8 assay, colony formation assay and scratch test were conducted to detect the effects of CYTOR and miR-205-5p on proliferation and migration of PC cells. Target gene prediction and screening and luciferase reporter assays were used to verify downstream target genes of CYTOR and miR-205-5p. The expression of Cyclin-dependent protein kinase 6 (CDK6) was detected by Western blotting. The tumor growth in mice was detected by in vivo experiments in nude mice. RESULTS: The expression of LncRNA CYTOR was significantly elevated in PC. Knockdown of CYTOR significantly inhibited cell proliferation and migration of PC cells. In vivo animal studies showed that CYTOR promoted tumor growth. MiR-205-5p was a direct target of CYTOR, and the expression levels of miR-205-5p were significantly reduced in PC cell lines. Furthermore, co-transfection of shCYTOR with miR-205-5p inhibitor partially abolished the effect of shCYTOR on cell proliferation and migration. In addition, CYTOR was negatively correlated with the expression of miR-205-5p. CDK6 was a direct target of miR-205-5p, and miR-205-5p mimic and sh CYTOR significantly reduced the expression levels of CDK6. CONCLUSION: CYTOR can promote PC progression by modulating the miR-205-5p/CDK6 axis, which may be a potential therapeutic target for PC.

Incorporation of in vitro techniques for botanicals dietary supplement safety assessment - Towards evaluation of developmental and reproductive toxicity (DART).

As complex mixtures, botanicals present unique challenges when assessing safe use, particularly when endpoint gaps exist that cannot be fully resolved by existing toxicological literature. Here we explore in vitro gene expression as well receptor binding and enzyme activity as alternative assays to inform on developmental and reproductive toxicity (DART) relevant modes of action, since DART data gaps are common for botanicals. Specifically, botanicals suspected to have DART effects, in addition to those with a significant history of use, were tested in these assays. Gene expression changes in a number of different cell types were analysed using the connectivity mapping approach (CMap) to identify modes of action through a functional read across approach. Taken together with ligand affinity data obtained using a set of molecular targets customised towards known DART relevant modes of action, it was possible to inform DART risk using functional analogues, potency comparisons and a margin of internal exposure approach.

Qualitative and quantitative image analysis of 16 cm wide-coverage computed tomography compared to new-generation dual-source CT.

BACKGROUND: Diagnostic quality of computed tomography (CT) images depends on numerous factors. Recently, two different modalities were introduced for coronary CT angiography (CCTA). OBJECTIVE: This study aims to compare the performance of 16 cm wide-coverage detector CT (WDCT) using the snapshot freeze technique with a new-generation dual-source CT (DSCT) with 66 ms temporal resolution for CCTA. METHODS: Total 101 patients with suspected coronary heart disease were enrolled. Of these, 50 and 51 patients were examined on WDCT and DSCT, respectively. CT values, image noise, signal-to-noise ratio, and contrast-to-noise ratio were measured. The image processing efficiency was recorded, followed by statistical comparison of diagnostic accuracy and radiation dose. RESULTS: Ninety-nine patients (98.02%) had satisfactory diagnostic image quality. DSCT was significantly better than WDCT in terms of quantitative image quality, image processing efficiency, and qualitative analysis (P < 0.05). However, radiation dose was significantly lower on WDCT (P < 0.05) as compared to DSCT. CONCLUSIONS: Image processing efficiency and image quality of CCTA was higher on DSCT compared to WDCT due to the limitation of maximal tube current of WDCT.

Radiomics for lung adenocarcinoma manifesting as pure ground-glass nodules: invasive prediction.

OBJECTIVES: To investigate the value of radiomics based on CT imaging in predicting invasive adenocarcinoma manifesting as pure ground-glass nodules (pGGNs). METHODS: This study enrolled 395 pGGNs with histopathology-confirmed benign nodules or adenocarcinoma. A total of 396 radiomic features were extracted from each labeled nodule. A Rad-score was constructed with the least absolute shrinkage and selection operator (LASSO) in the training set. Multivariate logistic regression analysis was conducted to establish the radiographic model and the combined radiographic-radiomics model. The predictive performance was validated by receiver operating characteristic (ROC) curve. Based on the multivariate logistic regression analysis, an individual prediction nomogram was developed and the clinical utility was assessed. RESULTS: Five radiomic features and four radiographic features were selected for predicting the invasive lesions. The combined radiographic-radiomics model (AUC 0.77; 95% CI, 0.69-0.86) performed better than the radiographic model (AUC 0.71; 95% CI, 0.62-0.81) and Rad-score (AUC 0.72; 95% CI, 0.63-0.81) in the validation set. The clinical utility of the individualized prediction nomogram developed using the Rad-score, margin, spiculation, and size was confirmed in the validation set. The decision curve analysis (DCA) indicated that using a model with Rad-score to predict the invasive lesion would be more beneficial than that without Rad-score and the clinical model. CONCLUSIONS: The proposed radiomics-based nomogram that incorporated the Rad-score, margin, spiculation, and size may be utilized as a noninvasive biomarker for the assessment of invasive prediction in patients with pGGNs. KEY POINTS: • CT-based radiomics analysis helps invasive prediction manifested as pGGNs. • The combined radiographic-radiomics model may be utilized as a noninvasive biomarker for predicting invasive lesion for pGGNs. • Radiomics-based individual nomogram may serve as a vital decision support tool to identify invasive pGGNs, obviating further workup and blind follow-up.

Use of connectivity mapping to support read across: A deeper dive using data from 186 chemicals, 19 cell lines and 2 case studies.

We previously demonstrated that the Connectivity Map (CMap) (Lamb et al., 2006) concept can be successfully applied to a predictive toxicology paradigm to generate meaningful MoA-based connections between chemicals (De Abrew et al., 2016). Here we expand both the chemical and biological (cell lines) domain for the method and demonstrate two applications, both in the area of read across. In the first application we demonstrate CMap's utility as a tool for testing biological relevance of source chemicals (analogs) during a chemistry led read across exercise. In the second application we demonstrate how CMap can be used to identify functionally relevant source chemicals (analogs) for a structure of interest (SOI)/target chemical with minimal knowledge of chemical structure. Finally, we highlight four factors: promiscuity of chemical, dose, cell line and timepoint as having significant impact on the output. We discuss the biological relevance of these four factors and incorporate them into a work flow.

Structure-Guided Design of Novel, Potent, and Selective Macrocyclic Plasma Kallikrein Inhibitors.

A series of macrocyclic analogues were designed and synthesized based on the cocrystal structure of small molecule plasma kallikrein (pKal) inhibitor, 2, with the pKal protease domain. This led to the discovery of a potent macrocyclic pKal inhibitor 29, with an IC50 of 2 nM for one olefinic isomer and 42.3 nM for the other olefinic isomer.

Targeting Notch1 inhibits invasion and angiogenesis of human breast cancer cells via inhibition Nuclear Factor-κB signaling.

Notch-1, a type-1 transmembrane protein, plays critical roles in the pathogenesis and progression of human malignancies, including breast cancer; however, the precise mechanism by which Notch-1 causes tumor cell invasion and angiogenesis remain unclear. Nuclear factor-κB (NF-κB), interleukin-8 (IL-8), vascular endothelial growth factor (VEGF), and matrix metalloproteinases (MMP) are critically involved in the processes of tumor cell invasion and metastasis, we investigated whether targeting Notch-1 could be mechanistically associated with the down-regulation of NF-κB, IL-8, VEGF, and MMP-9, resulting in the inhibition of invasion and angiogenesis of breast cancer cells. Our data showed that down-regulation of Notch-1 leads to the inactivation of NF-κB activity and inhibits the expression of its target genes, such as IL-8, VEGF and MMP-9. We also found that down-regulation of Notch-1 decreased cell invasion, and vice versa Consistent with these results, we also found that the down-regulation of Notch-1 not only decreased MMP-9 mRNA and its protein expression but also inhibited MMP-9 active form. Moreover, conditioned medium from Notch-1 siRNA-transfected breast cancer cells showed reduced levels of IL-8 and VEGF and, in turn, inhibited the tube formation of HUVECs, suggesting that down-regulation of Notch-1 leads to the inhibition of angiogenesis. Furthermore, conditioned medium from Notch-1 cDNA-transfected breast cancer cells showed increased levels of IL-8 and VEGF and, in turn, promoted the tube formation of HUVECs, suggesting that Notch-1 overexpression leads to the promotion of angiogenesis.We therefore concluded that down-regulation of Notch-1 leads to the inactivation NF-κB and its target genes (IL-8, MMP-9 and VEGF), resulting in the inhibition of invasion and angiogenesis.

Grouping 34 Chemicals Based on Mode of Action Using Connectivity Mapping.

Connectivity mapping is a method used in the pharmaceutical industry to find connections between small molecules, disease states, and genes. The concept can be applied to a predictive toxicology paradigm to find connections between chemicals, adverse events, and genes. In order to assess the applicability of the technique for predictive toxicology purposes, we performed gene array experiments on 34 different chemicals: bisphenol A, genistein, ethinyl-estradiol, tamoxifen, clofibrate, dehydorepiandrosterone, troglitazone, diethylhexyl phthalate, flutamide, trenbolone, phenobarbital, retinoic acid, thyroxine, 1α,25-dihydroxyvitamin D3, clobetasol, farnesol, chenodeoxycholic acid, progesterone, RU486, ketoconazole, valproic acid, desferrioxamine, amoxicillin, 6-aminonicotinamide, metformin, phenformin, methotrexate, vinblastine, ANIT (1-naphthyl isothiocyanate), griseofulvin, nicotine, imidacloprid, vorinostat, 2,3,7,8-tetrachloro-dibenzo-p-dioxin (TCDD) at the 6-, 24-, and 48-hour time points for 3 different concentrations in the 4 cell lines: MCF7, Ishikawa, HepaRG, and HepG2 GEO (super series accession no.: GSE69851). The 34 chemicals were grouped in to predefined mode of action (MOA)-based chemical classes based on current literature. Connectivity mapping was used to find linkages between each chemical and between chemical classes. Cell line-specific linkages were compared with each other and to test whether the method was platform and user independent, a similar analysis was performed against publicly available data. The study showed that the method can group chemicals based on MOAs and the inter-chemical class comparison alluded to connections between MOAs that were not predefined. Comparison to the publicly available data showed that the method is user and platform independent. The results provide an example of an alternate data analysis process for high-content data, beneficial for predictive toxicology, especially when grouping chemicals for read across purposes.

A novel transcriptomics based in vitro method to compare and predict hepatotoxicity based on mode of action.

High-content data have the potential to inform mechanism of action for toxicants. However, most data to support this notion have been generated in vivo. Because many cell lines and primary cells maintain a differentiated cell phenotype, it is possible that cells grown in culture may also be useful in predictive toxicology via high-content approaches such as whole-genome microarray. We evaluated global changes in gene expression in primary rat hepatocytes exposed to two concentrations of ten hepatotoxicants: acetaminophen (APAP), ß-naphthoflavone (BNF), chlorpromazine (CPZ), clofibrate (CLO), bis(2-ethylhexyl)phthalate (DEHP), diisononyl phthalate (DINP), methapyrilene (MP), valproic acid (VPA), phenobarbital (PB) and WY14643 at two separate time points. These compounds were selected to cover a range of mechanisms of toxicity, with some overlap in expected mechanism to address the question of how predictive gene expression analysis is, for a given mode of action. Gene expression microarray analysis was performed on cells after 24h and 48h of exposure to each chemical using Affymetrix microarrays. Cluster analysis suggests that the primary hepatocyte model was capable of responding to these hepatotoxicants, with changes in gene expression that appear to be mode of action-specific. Among the different methods used for analysis of the data, a combination method that used pathways (MOAs) to filter total probesets provided the most robust analysis. The analysis resulted in the phthalates clustering closely together, with the two other peroxisome proliferators, CLO and WY14643, eliciting similar responses at the whole-genome and pathway levels. The Cyp inducers PB, MP, CPZ and BNF also clustered together. VPA and APAP had profiles that were unique. A similar analysis was performed on externally available (TG-GATES) in vivo data for 6 of the chemicals (APAP, CLO, CPZ, MP, MP and WY14643) and compared to the in vitro result. These results indicate that transcription profiling using an in vitro assay may offer pertinent biological data to support predictions of in vivo hepatotoxicity potential.

An intact intermediate filament network is required for collateral sprouting of small diameter nerve fibers.

Expression of the intermediate filament (IF) protein peripherin is initiated during development at the time of axonal extension and increases during regeneration of nerve fibers. To test whether the IF network is essential for neuron process outgrowth in the mature organism in vivo, we disrupted endogenous peripherin IF in small-sized dorsal root ganglion (DRG) neurons in transgenic mice via expression of a mutant peripherin transgene under control of peripherin gene regulatory sequences. Anatomical and functional analyses showed that these neurons send peripheral and central axonal projections to correct targets, express correct neuropeptides, and mediate acute pain responses normally. However, disruption of IF significantly impaired the ability of uninjured small-sized DRG neurons to sprout collateral axons into adjacent denervated skin, indicating a critical role for intact IF in plasticity, specifically in compensatory nociceptive nerve sprouting.

Intron 1 is required for cell type-specific, but not injury-responsive, peripherin gene expression.

The "primitive" neurons of the peripheral nervous system (PNS) have the remarkable ability to regenerate new fibers. This regenerative process requires a sequence of gene activation and repression that is poorly understood. One gene that is almost exclusively expressed in neurons of the PNS and is activated after nerve injury is the peripherin intermediate filament gene, but little is known about the genomic elements that control either its restricted expression or its response to nerve injury in adult mice. Previous studies suggested that both 5' flanking sequence and intragenic regions were required for cell type-specific and injury-specific expression. To determine which intragenic regions were critical, mice were generated that expressed peripherin transgenes lacking different introns. Analyses of these mice revealed that deletion of introns 2-8 had no effect on either the cell type-specific or injury-specific expression of the peripherin gene; however, the remaining intron, intron 1, differentially bound Sp1 transcription-related proteins/protein complexes in extracts from peripherin-expressing and nonexpressing tissues. Furthermore, a transgene that lacked intron 1 was not expressed in many neurons that contain endogenous peripherin but was activated after injury. Thus, accurate cell type-specific peripherin gene expression in the PNS depends on elements within intron 1, but other sequences, most likely in the 5'flanking region, are required for activating the peripherin gene in response to nerve injury.