Adalimumab Dose Reduction and Withdrawal in Stable Non-Infectious Pediatric Uveitis: An Open-Label, Prospective, Pilot Study

PURPOSES

This study investigated the feasibility of adalimumab (ADA) dose reduction and withdrawal strategy in children with stable pediatric non-infectious uveitis (PNIU).

METHODS

This open-label prospective pilot trial recruited 18 stable PNIU patients (33 eyes) between two and eighteen years old who were treated with standard doses of ADA (20/40 mg every 2 weeks) plus oral methotrexate. The interval of ADA injection was extended to 4 weeks and followed up for 24 weeks. If the uveitis remained stable, ADA was discontinued and followed up for another 24 weeks. ADA was considered successfully stopped if no relapse occurred during this period. The relapse-free survival rate, best corrected visual acuity (BVCA), anterior chamber cell (ACC), vitritis, macular thickness (MT), and serum ADA levels were evaluated. Approval Number: 2021KYPJ201. ClinicalTrials.gov identifier: NCT05155592.

RESULTS

The relapse-free survival rate was 22.2% (4/18) at 48 weeks. 33.3% (6/18) of patients relapsed when ADA was given every 4 weeks, while 44.5% of patients (8/18) relapsed after ADA was stopped. The four patients successfully withdrawn from ADA were all diagnosed with BD. No statistically significant differences (p > 0.05) were observed in BCVA and MT between baseline and final follow-up. The proportion of ACC and vitritis exhibited an upward trend (p < 0.05) during follow-up. Serum ADA gradually decreased to zero during follow-up in both non-recurrence and recurrence groups.

CONCLUSIONS

In PNIU children who reached remission for 6 months, ADA dose reduction and withdrawal were associated with a high risk of inflammation recurrence. Timely adjustment of ADA to the last effective dosage frequency can regain control of the inflammation. Detection of ADA serum levels in patients with recurrence may help find the appropriate interval of ADA use.

[Acute macular neuroretinopathy: a case report]

A 16-year-old female patient experienced a rapid decline in bilateral visual acuity accompanied by central scotomas for 5 days following coronavirus disease 2019 infection. Ocular examination revealed findings consistent with acute macular neuroretinopathy. Structural en face imaging using optical coherence tomography demonstrated a wedge-shaped lesion with low reflectivity directed towards the fovea in both eyes. B-scan images revealed localized hyperreflective bands involving the outer nuclear layer and photoreceptor layer, with discontinuity of the ellipsoid zone. Based on clinical presentation and examination findings, a diagnosis of bilateral acute macular neuroretinopathy was established.

[Effect of preoperative anterior bony impingement on lateral collateral ankle ligament reconstruction]

Objective: To explore whether the combination of anterior bony impingement before surgery will affect the efficacy of the lateral collateral ankle ligament reconstruction surgery in patients with chronic ankle instability (CAI). Methods: A prospective cohort study. Patients with CAI who underwent lateral collateral ankle ligament reconstruction from January 2014 to October 2017 in the Department of Sports Medicine, Huashan Hospital, Fudan University were enrolled in this study. The patients were divided into no bony impingement group (NI group) and bony impingement group (BI group) according to the presence of bone impingement in front of the ankle during the operation. Preoperative American Orthopedic Foot and Ankle Society (AOFAS) score, Karlsson ankle functional socre (KAFS), Tegner score, visual analogue scale (VAS) of pain were extracted and were reevaluated at least 2 years after surgery as well as imaging evaluation of ankle. Results: A total of 59 patients were enrolled in this study. There were 29 patients in the NI group, 23 males and 6 females with a mean age of (28.4±7.1) years. And there were 30 cases in the BI group, 28 males and 2 females with a mean age of (31.9±8.6) years. The AOFAS, KAFS and Tegner scores in NI group increased from 65.8±10.6, 65.9±10.1 and 3.0 (3.0, 4.0) before the operation to 97.5±4.3, 97.8±4.7 and 6.0(5.0,6.0) after the operation, respectively; and the VAS decreased from 3.0(3.0, 4.0) to 0(0, 0); there were significant differences in those indexes before and after the operation (all P<0.05). The scores of AOFAS, KAFS and Tegner in BI group increased from 65.2±11.0, 64.2±10.0 and 3.0(3.0, 4.0) before the operation to 97.1±4.3, 97.3±4.3 and 5.0(4.0, 6.0) post the operation, respectively; and the VAS scores decreased from 3.0(3.0, 5.0) to 0(0, 1.0); there were significant differences in up-mentioned indexes before and after the surgery (all P<0.05). There was no significant differences in baseline and preoperative clinical function scores between the two groups (all P>0.05). No significant difference was found in postoperative AOFAS, KAFS and VAS scores between the two groups (all P>0.05), while postoperative Tegner score in the NI group was significantly higher than that in the BI group [6.0(5.0, 6.0) vs 5.0(4.0, 6.0), P=0.026]. Imaging evaluation of all patients showed that the reconstructed ligament was clearly visible, and the intraarticular injuries existing before surgery showed obvious signs of healing. Conclusion: Ankle lateral collateral ligament reconstruction for CAI with or without anterior bony impingement results in similar outcomes in ankle function, stability and pain levels.

[Clinical features and treatment outcome of patients with non-Hodgkin lymphoma-associated hemophagocytic lymphohistiocytosis]

Objective: To investigate the clinical features and effect of prognostic factors in patients with different pathological types of non-Hodgkin lymphoma-associated hemophagocytic lymphohistiocytosis. Methods: We collected and analyzed the clinical data of 89 patients with non-Hodgkin lymphoma-associated hemophagocytic lymphohistiocytosis who were treated at Huadong Hospital from March 2013 to May 2020. The data were analyzed via log-rank and Cox multivariate analyses. Results: The median overall survival time of the 89 cases was 10.2 months. Patients with B-cell lymphoma-associated hemophagocytic lymphohistiocytosis did not reach the median overall survival time. The median overall survival times of T-cell lymphoma-associated hemophagocytic lymphohistiocytosis and NK-cell lymphoma-associated hemophagocytic lymphohistiocytosis were 10.2 and 3.0 months, respectively. The pathological type of non-Hodgkin lymphoma (OS: P=0041, PFS: P=0.015) , ECOG score ≥ 3 (OS: P=0.031, PFS: P=0.030) , hematopoietic stem cell transplantation (OS: P=0.005, PFS: P=0.040) , lymphadenopathy (OS: P=0.007, PFS: P=0.012) , and splenomegaly (OS: P=0.276, PFS: P=0.324) were related to the overall survival and progression-free survival of patients with non-Hodgkin lymphoma-associated hemophagocytic lymphohistiocytosis. Splenectomy could improve the prognosis of patients with lymphoma-associated hemophagocytic lymphohistiocytosis, especially T-cell lymphoma-associated hemophagocytic lymphohistiocytosis. Conclusion: The clinical characteristics of patients with different pathological types of non-Hodgkin lymphoma-associated hemophagocytic lymphohistiocytosis were similar but were different in the overall survival rate and the effect of prognostic factors. We suggested that patients with non-Hodgkin lymphoma-associated hemophagocytic lymphohistiocytosis should receive more than combined chemotherapy. To improve the prognosis and survival rate of patients, those with B-cell lymphoma-associated hemophagocytic lymphohistiocytosis and NK-cell lymphoma-associated hemophagocytic lymphohistiocytosis promptly require hematopoietic stem cell transplantation. Moreover, patients with T-cell lymphoma-associated hemophagocytic lymphohistiocytosis should consider splenectomy.

[Ergonomic risk factors of carpal tunnel syndrome in workers of an automobile factory]

Objective: To investigate the occurrence of pain symptoms and risk factors of carpal tunnel syndrome (CTS) in automobile manufacturing workers and provide theoretical basis for the prevention of CTS. Methods: From Nov.5th to Nov.19th, 2017, 446 workers in an automobile factory whose work age was above one year participate in questionnaires by cluster sampling. Chi square test and multifactor logistics regression analysis were used to analyze the factors related to the occurrence of CTS pain symptoms in workers. Results: The incidence of CTS pain among workers in this automobile factory was 20.8%. Working in the same position for a long time (OR=2.137, 95% CI:1.183-3.862) and unable to work reasonably because of uncomfortable posture (OR =2.067, 95% CI: 1.075-3.974) were identified as the risk factors of CTS pain symptoms by multifactor logistics regression analysis. Working age (OR=0.537, 95%CI:0.311-0.926) and work break (OR= 0.489, 95% CI: 0.282-0.849) were identified as the benefit factors of CTS pain symptoms. Conclusion: The incidence of CTS pain in automobile manufacturing workers is related to the posture in the process of labor . Effective ergonomic interventions should be carried out to prevent the occurrence of CTS pain in automobile manufacturing workers.

[Protective effect and mechanism of tHBQ on acute silica dust exposure in rats]

Objective: To study the protective effects and possible mechanisms of tBHQ in rats exposed to acute silicadust. Methods: Male Wistar rats without specific pathogen SPF were randomly divided into control group、model group and intervention group, 32 rats for each group. Rats in the model group and the intervention group were treated with a single non exposed tracheal dust method to establish the rats exposed to silica model. The intervention group was intervened with 1% tBHQ solution, once a day. Each group 8 rats were sacrificed at 3,14,28,60d, respectively.The contents of IL-1,TNF-α, HYP,TGF-β in the lung tissue of rats were determined by enzyme linked immunosorbent assay(ELISA), the contents of MDA and the GSH-PX activity in lung tissue and serum of rats were determined by colorimetry. Results: Compared with the control group, the contents of IL-1 in the lung tissue of the model group and the intervention group at each time point increased with time, the contents of IL-1 of model group reached the maximum at 60d, the contents of IL-1 in intervention group reached the maximum at 28d(P<0.05), except 3 d. Compared with the control group, the contents of TGF-β and HYP in the lung tissue of the model group and the intervention group at 28 and 60 d increased with time and reached the maximum at 60d(P<0.05). Compared with the model group at each time point, the contents of IL-1, TGF-β, HYP in the intervention group were lower than those in the model group(P<0.05). Compared with the control group, the contents of MDA in lung tissue and serum of rats in model group and intervention group at different time points increased with time(P<0.05). Compared with the control group,the activity of GSH-PX in serum and lung tissue of rats in model group and intervention group decreased with time,there was no significant difference in 3d(P<0.05), compared with the control group, the activity of GSH-PX in the lung and serum tissue of in-tervenetion group was higher than model group except the 3d(P<0.05). Conclusion: The intervention of tBHQ can alleviate oxidative stress in rats exposed to silica dust to some extent, improve the antioxidant capacity of the body, and reduce the contents of IL-1, TNF-α, TGF-β,HYP in lung tissue,it has acertain impediment and inhibition effect on the inflammation and fibrosis caused by acute silica dust exposure.

[Molecular epidemiological study of human coronavirus OC43 in Shanghai from 2009-2016]

Objective: To understand the epidemiological characteristics of Human coronavirus (HCoV), the patterns of emergence and circulation, and the genotype distribution of human coronavirus OC43 (HCoV-OC43) from November, 2009 to April, 2016 in Shanghai. Methods: A total of 6 059 respiratory specimens, including pharyngeal swab, sputum, nasopharyngeal aspirates and alveolar lavage fluid, as well as relative clinical data were collected from patients with acute respiratory infections from seven sentinel hospitals during November, 2009 to April, 2016 in Shanghai. Respiratory specimens were tested by RT-PCR with HCoV-conserved primers and subsequently genotyped by DNA sequencing. Using specific primers to amplify and sequence full-length Spike (S), RNA-dependent RNA polymerase (RDRP) and nucleocapsid (N) gene from HCoV-OC43 positive samples. Further genotype and phylogenetic analysis of HCoV-OC43 were performed by conducting phylogenetic trees. Results: Among 6 059 patients, the total frequency of HCoV was 63 (1.04%), in which HCoV-OC43 was the most frequently detected species with 34 positive samples, followed by human coronavirus 229E (HCoV-229E) and human coronavirus HKU1 (HCoV-HKU1) with 18 and 10 positive sample respectively. However, other HCoV like human coronavirus NL63 (HCoV-NL63), severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle-East Respiratory Syndrome Coronavirus (MERS-CoV), were not been detected, which illustrated that HCoV-OC43 was the dominant subtype. The full-length of S, RDRP and N gene were obtained from 29 HCoV-OC43 positive samples. According to the sequence-analysis, 27 of which was genotype D, 2 of which was genotype B and others genotype, including genotype E, F and G, were not detected. The result indicated that the genotype D may be the dominant genotype. Further analysis of S protein that help HCoV-OC43 to entry host cell and stimulate the host immune system to produce neutralizing antibody found that two important functional domains in S protein, N-terminal domain (NTD) and receptor-binding domain (RBD) contained more amino acid substitution and positive selection sites, accompanied with amino acid insertion/deletion. 13 positive selection sites were all located in the NTD or RBD, 10 of which were located in the NTD and 3 in the RBD. Conclusion: Human coronavirus OC43 was the major circulation human coronaviurs in Shanghai from 2009 to 2016, in which genotype D was the dominant genotype. NTD and RBD regions of the S protein were hypervariable region during HCoV-OC43 evolution, and had amino acid substitutions as well as amino acid insertion/deletion.

Comparison and application of a novel genotyping method, semiautomated primer-specific and mispair extension analysis, and four other genotyping assays for detection of hepatitis C virus mixed-genotype infections

To date the true prevalence of hepatitis C virus (HCV) mixed-genotype infections has not been established mainly because currently available methods are not suitable for the detection of mixed genotypes in a viral population. A novel semiautomated genotyping method, primer-specific and mispair extension analysis (S-PSMEA), which is more reliable than other genotyping assays was developed for detection of HCV mixed-genotype infections. A genotype present at levels as low as 0.8% in a defined mix of HCV genotypes was detected, showing a 20-fold increase in sensitivity over that of direct DNA sequencing. A total of 434 HCV isolates were genotyped and analyzed for a comparative study of the accuracy between S-PSMEA and four current genotyping methods. The results showed that viruses in approximately 40% of the samples from this group determined to be infected with mixed genotypes by S-PSMEA were undetected by direct DNA sequencing due to its low sensitivity. Type-specific PCR, line probe assay, and restriction fragment length polymorphism analysis performed poorly, being able to identify only 38.5, 16.1, and 15.4% of mixed-genotype infections, respectively, that were detected by direct DNA sequencing. The prevalence of mixed-genotype infections detected by S-PSMEA was 7.9% (12 of 152 donors) among HCV-infected blood donors, 14.3% (15 of 105) among patients with chronic hepatitis C, and 17.1% (6 of 36) among thalassemia patients who had received multiple transfusions. The data lead us to conclude that HCV mixed-genotype infections are more common than previously estimated and that S-PSMEA may be the method of choice when detection of genotypes present at low levels in mixed-genotype infections is required due to its higher level of sensitivity.

Primer specific and mispair extension analysis (PSMEA) as a simple approach to fast genotyping

A simple method, primer specific and mispair extension analysis (PSMEA) with pfu DNA polymerase was developed for genotyping. PSMEA is based on the unique properties of 3'-->5' exonuclease proofreading activity. In the presence of an incomplete set of dNTPs, pfu was found to be extremely discriminative in nucleotide incorporation and proofreading at the initiation step of DNA synthesis, completely preventing primer extension when mispair(s) are found adjacent to the 3'-end of the primer. This has allowed us to accurately detect nucleotide variations, deletions and insertions for fast genotyping.

[A bacteriology analysis from infected root canals of human deciduous teeth]

OBJECTIVE: To provide a basis for therapy and prevention, the flora of infected root canals of human deciduous teeth was analyzed.METHODS: By immediate-enzyme method, the bacteria compositions of 22 cases with infected root canals of deciduous teeth, including 8 cases with acute periapical inflammation and 14 with chronic ones, were examined. RESULTS: Among 240 strains bactera, 200 strains were obligate anaerobes, belonging to the genera peptostreptococcus, bacteriodes, veillonella, eubacterrum, propionibacterium, actinomyces and fusobacterium. Bacteriodes and eusobacterium especially B. gingivalis and F. nucleatum have been more frequently isolated from root canals with acute periapical inflammation than that with chronic ones (P<0.05). In chronic cases, veillonella especially V. parvula, were more frequently isolated than acute inflammation. CONCLUSION: Periaplcal inflammation of deciduous teeth was mixed polymicrobial infections regardless of acute or chronic cases and anaerobic bacteria were dominated. B. gingivalis and F. nucleatum probably were related to acute periapical inflammation of deciduous teeth. The effect of V. parvula on chronic periapical innammation of deciduous teeth should not be neglected.

[The antibacterial efficacy to obligate anaerobes isolated from the infected root canal of deciduous teeth]

OBJECTIVE:The antibacterial efficacy of 7 kinds drugs to 4 kinds obligate anaerobes isolated from the infected canal of deciduous teeth and 4 kinds standard strains was tested.The results showed that FC,Metronidazole,Chloromycin,Cefradium have strong antibacterial effects on experimental strains,but Erythromycin and Norvancomycin Hydrochloridum were not so effective.

Flow cytometric immunofluorescence assay for detection of antibodies to human immunodeficiency virus type 1 using insoluble precursor forms of recombinant polyproteins as carriers and antigens

A new serological assay, the recombinant flow cytometric immunofluorescence assay (r-FIFA), was developed for the early detection of human immunodeficiency virus type 1 (HIV-1) antibodies by using recombinant insoluble forms of HIV-1 Gag-p45, Gag-gp41 chimeric protein, gp160, Po197 polyprotein as antigens and autologous carriers through flow cytometry. These recombinant proteins were expressed in insect cells by a baculovirus expression system. Eight anti-HIV-1 seroconversion panels, a low-titer anti-HIV-1 panel from Boston Biomedica Inc. (BBI), and three HIV-1 seroconversion specimens from the Provincial Health Laboratory of Ontario, Toronto, Ontario, Canada (PHL), were tested and analyzed by r-FIFA. In sensitivity comparisons between r-FIFA and tests licensed by the U.S. Food and Drug Administration, which were used to test all of the HIV-1 panels from BBI, detection of HIV-1 antibody by r-FIFA was on average greater than 20 days earlier than that by enzyme immunoassay. The sensitivity of r-FIFA has permitted the detection of HIV-1-specific immunoglobulin G (IgG), IgM, and IgA antibodies during seroconversion. A kinetic analysis of HIV-1 antibody production of r-FIFA has shown that either IgG or IgM, or both, can be detected, depending on the phase and type of the immune response in the HIV-1-infected individual. Both primary and secondary immune responses were observed during this period. The r-FIFA results suggest that implementation of r-FIFA may significantly reduce the "window" period from the time of infection to the time of seroconversion, with earlier detection of antibodies after initial infection. This would also make it possible for us to understand the immune response and the precise mechanisms of immunopathogenesis in the early period of HIV-1 infection.

Enzyme activities in four different forms of human immunodeficiency virus 1 pol gene products

Five cassettes of the pol gene of human immunodeficiency virus 1 were constructed and inserted under the control of the polyhedrin gene promoter of Autographa californica nuclear polyhedrosis virus by homologous recombination. The first cassette polF contains the full-length pol open reading frame; the second cassette pol100 starts with the first AUG codon of the pol gene and deletes 103 amino acids from the amino terminus of the pol gene product; the third cassette pol97 deletes the entire protease coding sequence; the fourth cassette pol66 deletes both the protease and endonuclease/integrase coding sequences; and the fifth cassette pol51 contains the reverse transcriptase coding sequences plus 39 3'-terminal nucleotides of the RNase H coding sequences. We have expressed these five forms of the pol gene in Spodoptera frugiperda SF9 cells and have analyzed for both reverse transcriptase and RNase H activities. The polF construct expressed several processed forms, 66 kDa, 51 kDa, and 34 kDa proteins, that were detected only by Western blot. In contrast, pol100, pol97, pol66, and pol51 products were expressed at high levels and were readily detectable in gels by staining. The levels of expression of these four products were estimated to be greater than 150 mg/liter of culture (5 x 10(8) cells). Activity gel analyses showed that the pol100, pol97, pol66, and pol51 products possess reverse transcriptase activity; however, only pol97 and pol66 have RNase H activity. Our results demonstrate that many forms, including partially cleaved forms of human immunodeficiency virus 1 pol gene products, possess reverse transcriptase activity but only certain forms have RNase H activity.

Properties of ornithine decarboxylase-antizyme from mammary gland of lactating rats

Ornithine decarboxylase-antizyme was induced in mammary gland of fasted lactating rats by administration of 1,3-diaminopropan-2-ol. Antizyme from mammary gland showed similar chemical and kinetic behavior to that previously reported by Canellakis and co-workers for antizyme from liver [J. S. Heller, W. F. Fong, and E. S. Canellakis (1976) Proc. Natl. Acad. Sci. USA 72, 1858-1862]; specifically the inhibitor was nondialyzable, heat labile, and ribonuclease insensitive, and the inhibition was time independent, proportional to the concentration of antizyme present, and noncompetitive with respect to the substrate, ornithine. However, ornithine decarboxylase-antizyme from mammary gland eluted from Sephadex G-75 with an apparent molecular mass of 55 kDa, compared with 27 kDa, for antizyme from liver under identical conditions. The elution pattern was unaffected by the presence of high salt concentrations, indicating that the larger size was not due to macromolecular complexes. The presence of antizyme-ornithine decarboxylase complex was detected in mammary gland of untreated lactating rats fasted for 6 or 24 h, thus indicating that antizyme plays a role in the regulation of ornithine decarboxylase in mammary gland under physiological conditions.

Variation in the HindIII restriction fragments of DNA from the Chinese Tian Tan strain of vaccinia virus

HindIII fragments D to P of DNA from a Chinese vaccine strain (Tian Tan) of vaccinia virus have been molecularly cloned into the plasmid pAT153 at the unique HindIII site. The Chinese strain DNA differs from a non-vaccine American strain (WR) in having an additional HindIII fragment (P). Twelve HindIII D clones and 12 HindIII F clones of the Chinese strain were analysed by digestion by EcoRI, BamHI, PstI and XhoI. Two forms of D (designated a and b) and of F (a and b) were demonstrated. In each the differences were detected as the presence of an additional EcoRI site, in Da and Fa. The HindIII Fa and Fb fragments of the Chinese strain were shown to differ significantly from the WR strain in their restriction site maps.

Spontaneous production of human gamma interferon in vitro by splenic lymphocytes of patients with idiopathic thrombocytopenic purpura

Lymphocytes derived from spleens of traffic trauma victims do not appear to produce human interferon (IFN) activity, spontaneously, in vitro. However, lymphocytes derived from spleens of four ITP patients were found to produce significant amounts of human IFN activity. The IFN activity produced by the splenic lymphocytes of ITP patients was neutralized by anti-gamma-IFN antisera but not anti-alpha or anti-beta antisera. The IFN activity was found to be unstable at pH 2.0 and at 56 degrees C. Thus the human IFN activity of splenic lymphocytes is characterized as human gamma-IFN. No human IFN activity was detectable in the serum of the ITP patients and it is not known whether the splenic lymphocytes of ITP patients also produce human gamma-IFN in vivo. The observations suggest that conditions prevail in the ITP state that predispose the splenic lymphocytes to produce human gamma-IFN without stimulation by exogenously added inducer.

Effect of 1,3-diaminopropan-2-o1, an inhibitor of ornithine decarboxylase, on the metabolic response of liver to insulin

The effect of diaminopropanol, an inhibitor of polyamine synthesis, on the metabolic response of liver to insulin was studied in streptozotocin-diabetic rats. Insulin elicited a prompt and very marked increase in ornithine and S-adenosylmethionine decarboxylase activities and in putrescine concentration. Pretreatment of rats with diaminopropanol prevented the increase in the decarboxylases and resulted in decreased spermidine and spermine content of liver. The insulin-induced increase in glycogen content was depressed by 50% and the increase in the rate of lipogenesis in vivo was completely prevented by prior injection of diaminopropanol. These studies implicate altered polyamine metabolism in the metabolic response of liver of streptozotocin-diabetic rats to insulin.

Effect of acriflavine and ethidium bromide on the synthesis of RNA of the peripheral nerve in the chick during development

The effect of the trypanocidal dyes acriflavine and ethidium bromide on the sedimentation pattern of tritium-labelled RNA of the sciatic nerve of chicks was studied. Tissues from 14-day embryos, 17-day embryos, and 3-day chicks were incubated with [5-3H]uridine in organ culture, in the presence and in the absence of the inhibitors. Acriflavine and especially ethidium bromide caused a selective inhibition of the labelling of the RNA species which sedimented between the 17.2 S and 5.8 S components of the bulk RNA in the older animals. The labelling of the RNA with sedimentation values higher than 17.2 S was not decreased by ethidium bromide during a 1.5 h incubation period, indicating that rRNA, rRNA precursors, or heterogeneous nuclear RNA was not affected by the drug.

RNA synthesis in peripheral nerve in the chick during development

The pattern of RNA synthesis was investigated in vitro in the sciatic nerve of the chicken. Nerve tissue from 14-day embryos, 17-day embryos, and 3-day chicks was incubated with [5-3H]-uridine for 0.5, 1.5, and 3.5 h. The RNA was isolated from the tissues and the purified preparations were fractionated by zone velocity centrifugation on sucrose gradients.The sedimentation properties of the rapidly labelled RNA changed in the three developmental stages. The proportion of the radioactivity in the light fractions of the RNA (5.8–17.2 S) increased with the age of the animals. In contrast, the specific activities of the heavy species decreased during nerve development. Pulse-chase experiments with unlabelled uridine and actinomycin D demonstrated the metabolic lability of the rapidly labelled RNA. The sedimentation properties of the pulse-labelled RNA of the cerebellum were the same in the three developmental stages.