Demonstrating the reliability of in vivo metabolomics based chemical grouping: towards best practice

While grouping/read-across is widely used to fill data gaps, chemical registration dossiers are often rejected due to weak category justifications based on structural similarity only. Metabolomics provides a route to robust chemical categories via evidence of shared molecular effects across source and target substances. To gain international acceptance, this approach must demonstrate high reliability, and best-practice guidance is required. The MetAbolomics ring Trial for CHemical groupING (MATCHING), comprising six industrial, government and academic ring-trial partners, evaluated inter-laboratory reproducibility and worked towards best-practice. An independent team selected eight substances (WY-14643, 4-chloro-3-nitroaniline, 17α-methyl-testosterone, trenbolone, aniline, dichlorprop-p, 2-chloroaniline, fenofibrate); ring-trial partners were blinded to their identities and modes-of-action. Plasma samples were derived from 28-day rat tests (two doses per substance), aliquoted, and distributed to partners. Each partner applied their preferred liquid chromatography-mass spectrometry (LC-MS) metabolomics workflows to acquire, process, quality assess, statistically analyze and report their grouping results to the European Chemicals Agency, to ensure the blinding conditions of the ring trial. Five of six partners, whose metabolomics datasets passed quality control, correctly identified the grouping of eight test substances into three categories, for both male and female rats. Strikingly, this was achieved even though a range of metabolomics approaches were used. Through assessing intrastudy quality-control samples, the sixth partner observed high technical variation and was unable to group the substances. By comparing workflows, we conclude that some heterogeneity in metabolomics methods is not detrimental to consistent grouping, and that assessing data quality prior to grouping is essential. We recommend development of international guidance for quality-control acceptance criteria. This study demonstrates the reliability of metabolomics for chemical grouping and works towards best-practice.

Comparison of Pulmonary and Extrapulmonary Models of Sepsis-Associated Acute Lung Injury

To compare different rat models of sepsis at different time points, based on pulmonary or extrapulmonary injury mechanisms, to identify a model which is more stable and reproducible to cause sepsis-associated acute lung injury (ALI). Adult male Sprague-Dawley rats were subjected to (1) cecal ligation and puncture (CLP) with single (CLP1 group) or two repeated through-and-through punctures (CLP2 group); (2) tail vein injection with lipopolysaccharide (LPS) of 10mg/kg (IV-LPS10 group) or 20 mg/kg (IV-LPS20 group); (3) intratracheal instillation with LPS of 10mg/kg (IT-LPS10 group) or 20mg/kg (IT-LPS20 group). Each of the model groups had a sham group. 7-day survival rates of each group were observed (n=15 for each group). Moreover, three time points were set for additional experimental studying in each model group: 4 hours, 24 hours and 48 hours after modeling (every time point, n=8 for each group). Rats were sacrificed to collect BALF and lung tissue samples at different time points for detection of IL-6, TNF-alpha, total protein concentration in BALF and MPO activity, HMGB1 protein expression in lung tissues, as well as the histopathological changes of lung tissues. More than 50 % of the rats died within 7 days in each model group, except for the IT-LPS10 group. In contrast, the mortality rates in the two IV-LPS groups as well as the IT-LPS20 group were significantly higher than that in IT-LPS10 group. Rats received LPS by intratracheal instillation exhibited evident histopathological changes and inflammatory exudation in the lung, but there was no evidence of lung injury in CLP and IV-LPS groups. Rat model of intratracheal instillation with LPS proved to be a more stable and reproducible animal model to cause sepsis-associated ALI than the extrapulmonary models of sepsis.

Mode of Action Hypothesis Testing in Chemical Safety Assessments Using Metabolomics as Supporting Evidence: Phenobarbital and Cyclobutrifluram Metabolomics Profile Comparison

In long term rodent studies administering Cyclobutrifluram (TYMIRIUM® Technology), a new agrochemical, there was a slight elevation of incidence of hepatocellular carcinomas in male CD-1 mice that was within the historical control range but appeared to be dose responsive. Cyclobutrifluram's ability to activate mouse constitutive androstane receptor (CAR) mediated gene transcription was confirmed in vitro, therefore a 28-day dietary toxicity study was conducted in vivo in male CD-1 mice to assess the CAR activation mode of action hypothesis of Cyclobutrifluram along with phenobarbital, a known CAR activator. In addition to other end points comprehensive (polar and lipidomic) hybrid metabolomics analyses were performed on terminal plasma and liver samples following 2-, 7- and 28-days dietary exposure to cyclobutrifluram and phenobarbital. The data generation and quality assessments were performed in line with the principles of the MEtabolomics standaRds Initiative in Toxicology (MERIT). First the full annotated feature set was used to compare the metabolomic changes induced by the administration of the two test substances using Shared and Unique Structures plots. This gave a comprehensive overview of the similarity of the two effect profiles showing good correlation and demonstrated that no other, alternative effect signatures were detected. Then the phenobarbital induced differentially abundant metabolites were selected, compared to the literature and their direction of change was assessed in cyclobutrifluram profiles, finding good agreement. Both approaches concluded that the metabolomics data supports the CAR activation hypothesis. Comparison of the metabolomic effect profiles can be a line of evidence in mode of action hypothesis testing in the chemical risk assessment process.

P-551 High concordance of the embryonic cell-free DNA with the inner cell mass: impact of blastocyst quality, patient age and mode of fertilization

Study question

Does the embryonic cell-free DNA (cfDNA) in the culture medium represent the chromosomal content of the inner cell mass (ICM)? Which factors impact concordance rates?

Summary answer

There is high ploidy concordance between ICM biopsies and embryonic cfDNA. This value is independent of female age, insemination technique and embryo quality.

What is known already

The existence of embryonic cfDNA in spent blastocyst medium (SBM) has been confirmed in recent studies, opening a new era of possibilities for non-invasive preimplantation genetic testing for aneuploidy (niPGT-A). High concordance rates of cfDNA with trophectoderm (TE) biopsies and with whole blastocysts have been reported. However, the compartment(s) from where this DNA originates remain unclear. Both TE and ICM are potential sources, but, at the moment, the origin of this cfDNA is unknown as well as the mechanisms underlying its secretion into the medium.

Study design, size, duration

We carried out a prospective study to investigate the concordance of cfDNA with the corresponding TE and ICM biopsies. 141 day-6/7 blastocysts were donated for research after written informed consent signature for the project approved by the Ethics Committee. Embryos underwent TE biopsy and SBM collection in the same PGT-A cycle. ICM biopsy in thawed blastocysts was performed after TE biopsy diagnosis. cfDNA, TE and ICM biopsies were analyzed from January 2019 to November 2021.

Participants/materials, setting, methods

Embryos were cultured in routine conditions up to day 4. They were then washed and transferred to a new 10μl culture medium droplet. On day 6, SBM was collected and frozen at -20 °C; and blastocyst biopsy and vitrification were performed. Subsequently, blastocysts were thawed and ICM biopsy was conducted. All samples were analyzed by NGS (Ion ReproSeq PGS kit, ThermoFisher Scientific) and the results were analyzed with customized algorithms for TE, ICM and cfDNA.

Main results and the role of chance

In combination, the three sample types (cfDNA, ICM and TE) were informative in 81.6% of the blastocysts (115/141).

Considering the ICM as the reference, ploidy concordance (i.e. being both euploid or aneuploid) for cfDNA was 86.1% (99/115) and for TE was 89.6% (103/115), without statistical difference. False positive rates were similar for cfDNA and for TE biopsies (6.1% and 9.6%, respectively), and false negative rates were not significantly different, but higher in cfDNA (7.8%) than in TE (0.9%), due to potential contamination with maternal DNA. Ploidy concordance between embryo cfDNA and TE biopsies was 89.6% (103/115).

When the results were stratified by female age (≤37 or > 37 years), insemination technique (ICSI or IVF), blastocyst expansion degree (expanded, hatching or fully hatched), and ICM/TE quality (A or B), the informativity of the cfDNA was very similar between the different groups and ranged from 83.7% to 100%. Nevertheless, there were subtle differences for ICM-cfDNA ploidy concordance. It was slightly increased for the older female age group (88.3% vs 83.6% female age ≤37) as well as for ICSI (89.7% vs 82.5% in IVF) and for ICM quality B (88.4% vs 80.0% for ICM A). None of those differences reached statistical significance.

Limitations, reasons for caution

When stratifying according to the different criteria, the sample size analyzed was too small to draw strong conclusions. Therefore, more studies, with bigger sample size, are needed to replicate the results.

Wider implications of the findings

The embryonic cfDNA released to the culture medium provides information of the overall blastocyst chromosomal constitution, as suggested by the high ploidy concordance rates reported between ICM and cfDNA. This supports the use of niPGT-A as an alternative to other invasive aneuploidy detection methods that require a biopsy.

Trial registration number

ClinicalTrials.gov. ID NCT03520933

Induction and Maintenance of Local Structural Durability for High-Energy Nickel-Rich Layered Oxides

Nickel-rich layered oxides are one of the most promising cathode candidates for next-generation high-energy-density lithium-ion batteries. However, due to similar ion radius between Li⁺ and Ni²⁺ (0.76 and 0.69 Å), the Li⁺ /Ni²⁺ mixing phenomenon seriously hinders the migration of Li⁺ and increases kinetic barrier of Li⁺ diffusion, resulting in limited rate capability. In this work, the introduction of Ce⁴⁺ to effectively improve electrochemical properties of Ni-rich cathode materials is proposed. The LiNi_0.8 Co_0.15 Al_0.05 O₂ (LNCA) is modified with an additional precursor oxidization process using an appropriate amount of (NH₄ )₂ Ce(NO₃ )₆ . The Ce(NO₃ )₆ ^2- easily obtains electrons and generates reduction reactions, while Ni(OH)₂ is prone to electron loss and oxidation reaction. The participation of (NH₄ )₂ Ce(NO₃ )₆ can promote the oxidation of Ni²⁺ to Ni³⁺ , thereby reducing the Li⁺ /Ni²⁺ mixing and increasing the structural stability of LNCA samples. Ce⁴⁺ cation doping can impede Li⁺ /Ni²⁺ mixing of LNCA cathode materials upon the long-term cycles. Both rate performance and long-term cyclability of Li[Ni_0.8 Co_0.15 Al_0.05 ]_0.97 Ce_0.03 O₂ (LNCA-Ce0.03) sample are significantly improved. Besides, a practical pouch cell based on the cathode presents sufficient gravimetric energy density (≈300 Wh kg^-1 ) and cycling stability (capacity retention of 81.3% after 500 cycles at 1 C).

Economic burden of public health care and hospitalisation associated with COVID-19 in China

OBJECTIVES

This study aimed to evaluate the socio-economic burden imposed on the Chinese healthcare system during the coronavirus disease 2019 (COVID-19) pandemic.

STUDY DESIGN

A cross-sectional study was used to investigate how COVID-19 impacted health and medical costs in China. Data were derived from a subdivision of the Centers for Disease control and Prevention of China.

METHODS

We prospectively collected information from the Centers for Disease Control and Prevention and the designated hospitals to determine the cost of public health care and hospitalisation due to COVID-19. We estimated the resource use and direct medical costs associated with public health.

RESULTS

The average costs, per case, for specimen collection and nucleic acid testing (NAT [specifically, polymerase chain reaction {PCR}]) in low-risk populations were $29.49 and $53.44, respectively; however, the average cost of NAT in high-risk populations was $297.94 per capita. The average costs per 1000 population for epidemiological surveys, disinfectant, health education and centralised isolation were $49.54, $247.01, $90.22 and $543.72, respectively. A single hospitalisation for COVID-19 in China cost a median of $2158.06 ($1961.13-$2325.65) in direct medical costs incurred only during hospitalisation, whereas the total costs associated with hospitalisation of patients with COVID-19 were estimated to have reached nearly $373.20 million in China as of 20, May, 2020. The cost of public health care associated with COVID-19 as of 20, May, 2020 ($6.83 billion) was 18.31 times that of hospitalisation.

CONCLUSIONS

This study highlights the magnitude of resources needed to treat patients with COVID-19 and control the COVID-19 pandemic. Public health measures implemented by the Chinese government have been valuable in reducing the infection rate and may be cost-effective ways to control emerging infectious diseases.

P–225 The effect of rapid and delayed insemination on reproductive outcome in conventional insemination and intracytoplasmic sperm injection invitro-fertilization cycles

Study question

Does rapid or delayed insemination after egg retrieval affect fertilization, blastocyst development and live birth rates in CI and ICSI cycles?

Summary answer

When performing CI or ICSI <1.5h and >6.5h after retrieval, detrimental effects are moderate on fertilization but do not impact blastocyst usage and birth rates.

What is known already

Several studies have shown that CIor ICSI performed between 3 to 5 h after oocyte retrieval has improved laboratory outcomes. However, some studies indicate that insemination of oocytes, by either CI or ICSI, within 2 hours or more than 8 hours after oocyte retrieval has a detrimental effect on the reproductive outcome. With some ART centres experiencing an increase in workload, respecting these exact time intervals is frequently challenging.

Study design, size, duration

A single-center retrospective cohort analysis was performed on 6559 patients (9575 retrievals and insemination cycles) between January 1st2017 to July 31st2019. The main outcome measures were live-birth rates. Secondary outcomes included analysis of fertilization per all oocytes retrieved, blastocyst utilization, clinical pregnancy, and miscarriage rates. All analyses used time of insemination categorized in both CI and ICSI cycles. Fertilization rates across categories was analyzed by ANOVA and pregnancy outcomes compared using Chi-square tests.

Participants/materials, setting, methods

As part of laboratory protocol, oocyte retrieval was performed 36 h post-trigger. Cycles involving injection with testicular/epidydimal sperm, donor or frozen oocytes were excluded. The time interval between oocyte retrieval and insemination was analyzed in eight categories: 0 (0- <0.5h), 1 (0.5-<1.5h), 2 (1.5-<2.5h), 3 (2.5-<3.5h), 4 (3.5-<4.5), 5 (4.5-<5.5), 6 (5.5-<6.5) and 7 (6.5-<8h). The number of retrievals in each group (0–7) was 586, 1594, 1644, 1796, 1836, 1351, 641 and 127 respectively.

Main results and the role of chance

This study had a mean patient age of 36.0 years and mean of 12.2 oocytes per retrieval in each category. There were 4,955 CI and 4,620 ICSI retrievals. The smallest groups were time category 7 and 0 for CI and ICSI respectively. The results showed that the mean fertilization rate per egg retrieved for CI ranged from 54.1 to 64.9% with a significant difference between time category 0 and 5 (p < 0.001) and category 1 and 5 (p < 0.0.001). Mean fertilization rate for ICSI per egg retrieved ranged from 52.8 to 67.3% with no significant difference between time categories compared to category 5. Blastocyst utilization rate for CI and ICSI were not significantly different for all time categories. In the CI and ICSI groups there were 6,540 and 6,178 total fresh and frozen transfers. The miscarriage and clinical pregnancy rate in CI and ICSI were not significantly different across time categories. The overall mean live birth rate for CI was 32.4% (range: 23.1 to 35.5%). Live-birth rates differed significantly (p = 0.04) in CI with time categories 0 and 7 the lowest. In the ICSI group, the overall mean live birth rate was 30.8% (range: 29.1 to 35.7%),with no significant differences between time categories.

Limitations, reasons for caution

As this is a retrospective study, the influence of uncontrolled variables cannot be excluded. The group spread was uneven with the early and late time categories having the lowest number of representative retrievals and this could have affected the results obtained.

Wider implications of the findings: Our results indicate that both CI and ICSI are optimal when performed between 1.5–6.5 hours after oocyte retrieval. Further prospective studies on reproductive outcomes related to time of insemination are warranted. This data indicates a minimal detrimental effect when it is untenable to follow strict insemination time intervals.

Trial registration number

2015P000122

Resveratrol proniosomes as a convenient nanoingredient for functional food

Proniosomes are free-flowing powders composed of water-soluble carriers blended with surfactants, which form niosomes upon hydration. In this work, proniosomal formulations containing the natural antioxidant resveratrol (RSV) were prepared and fully characterized. A pre-formulation study on RSV-loaded niosomes was carried out to determine the most promising ratio between the two surfactants, Tween 20 and Span 60, in terms of entrapment efficiency and antioxidant activity. The optimized formulae were subsequently adapted to be prepared as proniosomes by the slurry method, including lactose or maltodextrin as carriers. The impact of surfactants and carriers properties on size, entrapment efficiency and release kinetics of proniosomes were evaluated. In vitro release of RSV in simulated gastric and intestinal media was determined, as well as the vesicular stability. Moreover, the biocompatibility of the formulations was determined on intestinal cells in vitro. Overall, the developed proniosomes provide promising nanoingredient for functional food, improving resveratrol stability and bioavailability.

Meta-analysis of the influence of lifestyle changes for preoperative weight loss on surgical outcomes

Background

The aim was to investigate whether preoperative weight loss results in improved clinical outcomes in surgical patients with clinically significant obesity.

Methods

This was a systematic review and aggregate data meta-analysis of RCTs and cohort studies. PubMed, MEDLINE, Embase and CINAHL Plus databases were searched from inception to February 2018. Eligibility criteria were: studies assessing the effect of weight loss interventions (low-energy diets with or without an exercise component) on clinical outcomes in patients undergoing any surgical procedure. Data on 30-day or all-cause in-hospital mortality were extracted and synthesized in meta-analyses. Postoperative thromboembolic complications, duration of surgery, infection and duration of hospital stay were also assessed.

Results

A total of 6060 patients in four RCTs and 12 cohort studies, all from European and North American centres, were identified. Most were in the field of bariatric surgery and all had some methodological limitations. The pooled effect estimate suggested that preoperative weight loss programmes were effective, leading to significant weight reduction compared with controls: mean difference –7·42 (95 per cent c.i. –10·09 to –4·74) kg (P < 0·001). Preoperative weight loss interventions were not associated with a reduction in perioperative mortality (odds ratio 1·41, 95 per cent c.i. 0·24 to 8·40; I2 = 0 per cent, P = 0·66) but the event rate was low. The weight loss groups had shorter hospital stay (by 27 per cent). No differences were found for morbidity.

Conclusion

This limited preoperative weight loss has advantages but may not alter the postoperative morbidity or mortality risk.

A novel splice site mutation of the PRKAR1A gene, C.440+5 G>C, in a Chinese family with Carney complex

BACKGROUND

Carney complex (CNC) is an extremely rare, multiple endocrine neoplasia syndrome that occurs in an autosomal dominant manner. Mutations in PRKAR1A have been reported to be a common genetic cause of CNC.

METHODS

In this study, we reported a Chinese pedigree of CNC that manifests mainly as spotty skin pigmentation and primary pigmented nodular adrenocortical disease. Whole blood samples of this pedigree were collected for DNA/RNA analysis. Polymerase chain reaction (PCR) and reverse-transcription polymerase chain reaction analyses were performed to amplify the 11 exons and adjacent introns of PRKAR1A. Direct sequencing was used to detect the mutation, and DNA from 70 Han Chinese people was extracted and sequenced as a control to estimate the frequency of the identified mutation.

RESULTS

Within the pedigree, ten patients with CNC were identified, and a novel heterozygous mutation (c.440+5 G>C in intron 4a) was identified in the PRKAR1A gene. PCR amplification of cDNA from the control subjects and patients was performed. Agarose gel electrophoresis showed only one wild-type band in the cDNA corresponding to the former group, whereas an extra band was present in samples from the latter group corresponding to the skipping of exon 4a; this confirms that the variant affects PRKAR1A splicing.

CONCLUSION

In conclusion, the c.440+5 G>C mutation is a new splice site mutation that has not been reported and has the potential to broaden the mutational spectrum of PRKAR1A that is associated with CNC, which would facilitate genetic diagnosis and counseling for CNC.

Loss of p300 accelerates MDS-associated leukemogenesis

The role that changes in DNA methylation and histone modifications have in human malignancies is poorly understood. p300 and CREB-binding protein (CBP), two distinct but highly homologous lysine acetyltransferases, are mutated in several cancers, suggesting their role as tumor suppressors. In the current study, we found that deletion of p300, but not CBP, markedly accelerated the leukemogenesis ofNup98-HoxD13 (NHD13) transgenic mice, an animal model that phenotypically copies human myelodysplastic syndrome (MDS). p300 deletion restored the ability of NHD13 expressing hematopoietic stem and progenitor cells (HSPCs) to self-renew in vitro, and to expand in vivo, with an increase in stem cell symmetric self-renewal divisions and a decrease in apoptosis. Furthermore, loss of p300, but not CBP, promoted cytokine signaling, including enhanced activation of the MAPK and JAK/STAT pathways in the HSPC compartment. Altogether, our data indicate that p300 has a pivotal role in blocking the transformation of MDS to acute myeloid leukemia, a role distinct from that of CBP.

Immunohistochemical markers of CYP3A4 and CYP3A7: a new tool towards personalized pharmacotherapy of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) represents a major global health problem, since more than 90% of primary liver cancers worldwide are HCC. Most cases of HCC are secondary to viral hepatitis infection (hepatitis B or C), alcoholism and cirrhosis. Sorafenib, an oral tyrosine kinase inhibitor that suppresses tumor proliferation and angiogenesis, emerged as the first effective systemic treatment for HCC after 30 years of research, and is currently the standard-of-care for patients with advanced HCC. Sorafenib is metabolized by cytochrome P450 (CYP450), particularly from the 3A4 isoform, producing two main metabolites: the N-oxide and the N-hydroxymethyl metabolite. We studied 11 HCC sample showing the presence of CYP3A4 and CYP3A7 in most of the samples analysed. Specifically, the immunoreactivity of CYP3A4 was stronger and more widespread than that of CYP3A7. The CYP3A4 immunoreactivity was observed in surrounding hepatocytes in 8 out of 11 cases; while the CYP3A7 immunostaining was found in normal liver cells, in 7 out of 11 cases. These results suggest the existence of a marked inter-individual variability regarding the presence of the isoforms of CYP3A. In addition, since sorafenib is metabolized by CYP3A4, but not by CYP3A7, an overexpression of CYP3A4 may lead to an increase in the degradation of the drug and then to clinical ineffectiveness. These results might implicate the necessity of an individualized approach in the treatment of HCC as positivity to CYP3A4 in HCC liver samples might predict a scarce response to sorafenib.

INPP4B is an oncogenic regulator in human colon cancer

Inositol polyphosphate 4-phosphatase type II (INPP4B) negatively regulates phosphatidylinositol 3-kinase signaling and is a tumor suppressor in some types of cancers. However, we have found that it is frequently upregulated in human colon cancer cells. Here we show that silencing of INPP4B blocks activation of Akt and serum- and glucocorticoid-regulated kinase 3 (SGK3), inhibits colon cancer cell proliferation and retards colon cancer xenograft growth. Conversely, overexpression of INPP4B increases proliferation and triggers anchorage-independent growth of normal colon epithelial cells. Moreover, we demonstrate that the effect of INPP4B on Akt and SGK3 is associated with inactivation of phosphate and tensin homolog through its protein phosphatase activity and that the increase in INPP4B is due to Ets-1-mediated transcriptional upregulation in colon cancer cells. Collectively, these results suggest that INPP4B may function as an oncogenic driver in colon cancer, with potential implications for targeting INPP4B as a novel approach to treat this disease.

Adipocytes contribute to resistance of human melanoma cells to chemotherapy and targeted therapy

Epidemiological evidence has linked the development and progression of several cancers including melanoma with obesity. However, whether obesity impinges on responses of cancer cells to treatment remains less understood. Here we report that human adipocytes contribute to resistance of melanoma cells to various therapeutic agents. Exposure to media from adipocyte cultures (adipocyte media) increased cell proliferation and reduced sensitivity of melanoma cells to apoptosis induced by diverse chemotherapeutic drugs, including the DNA-damaging drug cisplatin, the microtubuletargeting agent docetaxel, and the histone deacetylase inhibitor SAHA. This was associated with increased activation of PI3K/Akt and MEK/ERK signaling, and was attenuated by a PI3K or MEK inhibitor. The effect of adipocyte media on melanoma cells was, at least in part, due to the interaction between the adipokine leptin and its long form receptor OB-Rb, in that immunodepletion of leptin in adipocyte media or siRNA knockdown of OB-Rb in melanoma cells reversed the increase in Akt and ERK activation, enhancement in cell proliferation, and importantly, protection of melanoma cells against the drugs. In support, recombinant leptin partially recapitulated the effect of adipocyte media on melanoma cells. Of note, OB-Rb was increased on the surface of melanoma cells compared to melanocytes, whereas leptin short form receptors appeared to be suppressed post-transcriptionally, suggesting that OB-Rb was selectively upregulated in melanoma cells. Collectively, these results indicate that adipocytes contribute to the resistance of melanoma cells to chemotherapeutic drugs and agents targeting the PI3K/Akt and MEK/ERK pathways, and suggest that inhibition of the leptin/ OB-Rb system may be useful to improve the efficacy of multiple therapeutic approaches in the treatment of melanoma.

Nanocrystals as tool to improve piroxicam dissolution rate in novel orally disintegrating tablets

In this paper, orally disintegrating tablets (ODT) were prepared using nanocrystal formulations in order to optimise dissolution properties of lipophilic, poorly soluble drug piroxicam (PRX). Different nanocrystal formulations were prepared using a high pressure homogenisation technique and poloxamer 188 as stabiliser. Characterisation of PRX nanocrystal ODT was carried out by infrared spectroscopy (FTIR), X-ray powder diffractometry (XRPD), differential scanning calorimetry and photon correlation spectroscopy. Dissolution study of PRX ODT was performed in distilled water (pH 5.5) and was compared to that of PRX coarse suspension ODT, PRX/poloxamer 188 physical mixture and bulk PRX samples. The XRPD and FTIR studies demonstrated that the homogenisation process led to a polymorphic transition from form I (bulk commercial PRX) to form III and monohydrate form of the nanocrystals. All ODT formulations prepared using PRX nanosuspensions showed a higher PRX dissolution rate compared with the ODT prepared with the coarse PRX. Since the solubility of the different PRX polymorphic forms increased only slightly from bulk PRX (form I) to monohydrate, form II and form III, we can conclude that the improvement in PRX dissolution rate is mainly caused by the increased surface-to-volume ratio due to the submicron dimension of the drug particles.

Requirements specification and analysis of digital systems using fuzzy and marked Petri nets

Fuzzy information often appears in the system requirements. Fuzzy Petri nets (FPN) are Petri nets in which certain fuzzy truth values are assigned to its transitions. We show how the FPN model can be used for formal specification and verification of digital systems. The consistent FPN model is actually a state machine, from which we can obtain a consistent marked Petri net (MPN) model. Based on the consistent MPN model, the hardware prototype at register transfer level can be easily induced by using the optimization rules. Finally, main results are presented in the form of three theorems and are supported by some experiments.

Evaluation of various POSSUM models for predicting mortality in patients undergoing elective oesophagectomy for carcinoma

Background

The aim of the study was to validate the use of the Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity (POSSUM), Portsmouth (P) POSSUM and upper gastrointestinal (O) POSSUM models in patients undergoing elective thoracic oesophagectomy for carcinoma.

Methods

The observed in-hospital mortality rates in 545 patients undergoing elective thoracic oesophagectomy for squamous cell carcinoma of the oesophagus in all public hospitals in Hong Kong was compared with rates predicted by POSSUM, P-POSSUM and O-POSSUM. The discriminatory power of these models was assessed using receiver–operator characteristic (ROC) curve analysis.

Results

The observed mortality rate was 5·5 per cent, whereas rates predicted by POSSUM, P-POSSUM and O-POSSUM were 15·0, 4·7 and 10·9 per cent respectively. P-POSSUM showed no lack of fit (P = 0·814), but POSSUM (P < 0·001) and O-POSSUM (P = 0·002) showed lack of fit against observed mortality. POSSUM overpredicted mortality across nearly all risk groups, whereas O-POSSUM overpredicted mortality in patients with low physiological scores and in older patients. POSSUM (area under ROC curve 0·776) and P-POSSUM (0·776) showed equally good discriminatory power but O-POSSUM (0·676) was inferior.

Conclusion

P-POSSUM provided the most accurate prediction of in-hospital mortality in this group of patients who had elective oesophagectomy.

Adaptive filtering of evoked potentials using higher-order adaptive signal enhancer with genetic-type variable step-size prefilter

An adaptive signal enhancer based on third-order statistics with a genetic-type, variable step-size prefilter is introduced to recover evoked potentials (EPs). EPs are usually embedded in the ongoing electroencephalogram with a very low signal-to-noise ratio (SNR). As a higher-order statistics technique has a natural tolerance to Gaussian noise, it is applicable for filtering EPs. An adaptive signal enhancer based on third-order statistics was used as the major filter in this study. However, the efficiency of the adaptive signal enhancer was reduced when the total power of uncorrelated noises was large. To improve the performance for EPs under poor SNR, a low-noise signal is required. Therefore a prefilter with a genetic-type, variable step-size algorithm was employed to enhance the SNR of the signal in this study. The fundamental idea of a genetic-type, variable step-size algorithm is that its step-sizes are regularly readjusted to optimum. Therefore this algorithm can be used as a prefilter with different noise levels. Experimental results showed that, for filtering EPs, the proposed scheme is superior to the adaptive signal enhancer with a normalised least mean square algorithm.

[Immunohistochemical localization of matrix metalloproteinases (MMP) and tissue inhibitors of metalloproteinases (TIMP) in tuberculous pleuritis]

Matrix metalloproteinases (MMP) and tissue inhibitors of metalloproteinases (TIMP) have been found by ELISA and gelatine zymography in different concentrations in pleural fluid in tuberculous (TB) pleuritis. For further differentiation MMP and TIMP were localized in pleural biopsies by immunhistochemical staining with antibodies directed against MMP-1, MMP-2, MMP-3, MMP-9, TIMP-1, and TIMP-2 using the Labelled-Avidin-Biotin (LAB). Immunohistological reactivity of MMP-1 was found in epitheloidcellular histiocytes, Langhans' giant cells, lymphocytes, macrophages, as well as in fibroblasts of granulomatous reactions. MMP-2 was found in a few epitheloid cellular histiocytes, fibroblasts, and inflammatory cells. MMP-3 was weakly positive in a few lymphocytes only. MMP-9 was found in a few fibroblasts, epitheloid cells, and inflammatory cells, foremost, however, in pleural mesothial cells. A few fibroblasts only showed immunoreactivity of TIMP-1 and TIMP-2. The observed inhomogenous staining pattern could be explained by the different state of activation of individual cellular units. In conclusion, the immunohistochemical demonstration of MMP and TIMP in pleural cells and tissue structures indicates their local involvement in fibrosing reactions in TB-pleuritis.

Comparison of L-bupivacaine 0.75% and lidocaine 2% with bupivacaine 0.75% and lidocaine 2% for peribulbar anaesthesia

BACKGROUND

L-Bupivacaine has a safer side-effect profile than bupivacaine. We compared the efficacy of a mixture of L-bupivacaine 0.75% and lidocaine 2% with bupivacaine 0.75% and lidocaine 2% for peribulbar anaesthesia in cataract surgery.

METHODS

Ninety patients were allocated randomly to receive 8 ml of a mixture of equal parts of bupivacaine 0.75% and lidocaine 2% or an equal volume of L-bupivacaine and lidocaine 2%. Hyaluronidase 15 IU ml(-1) was added to both solutions.

RESULTS

There were significant differences between the groups in clinical end-points. The median time at which the block was adequate to start surgery was 4 min (interquartile range 4-8 min) in the bupivacaine group and 8 min (5-12 min) in the L-bupivacaine group (P=0.002). Median ocular and eyelid movement scores were similarly significantly decreased in the bupivacaine group compared with the L-bupivacaine group at all times (P</=0.03). There was no difference between groups in the incidence of minor complications.

CONCLUSIONS

A mixture of bupivacaine 0.75% and lidocaine 2% provides faster onset time than a mixture of L-bupivacaine 0.75% and lidocaine 2%.

Discriminating two classes of toxicants through expression analysis of HepG2 cells with DNA arrays

Microarray technology provides a rapid and cost-effective method to associate specific cellular responses with unique gene expression patterns. If characteristic expression patterns of a small number of genes could be associated with drug toxicity, this association may be used for toxicity prediction, and thereby to reduce the need for traditional toxicity testing. To test this hypothesis, we have designed an array composed of 92 known human genes of toxicological interest (including seven housekeeping genes) and eight bacterial controls. HepG2 cells were treated with either ethanol or one of two quinone containing anticancer drugs, mitomycin C or doxorubicin. RNA was isolated from treated and untreated cells, differentially labeled with fluorescent dyes, and then hybridized to the array. Our results show that the expression patterns induced by ethanol and the anticancer drugs are different. Both of the anticancer drugs, but not ethanol had a differential effect on the regulation of several genes, including CYP4F2/3, CYP3A3, TNFRSF6 and CHES1, demonstrating that the two drugs might function through a similar mechanism, which differs from that of ethanol. These results suggest that microarray-based expression analysis may offer a rapid and efficient means for assessing drug toxicity.

Transcript map and comparative analysis of the 1.5-Mb commonly deleted segment of human 5q31 in malignant myeloid diseases with a del(5q)

Loss of a whole chromosome 5, or a del(5q), are recurring abnormalities in malignant myeloid diseases. In previous studies, we defined a commonly deleted segment (CDS) of 1.5 Mb between D5S479 and D5S500 in patients with a del(5q), and we established a P1 artificial chromosome-based contig encompassing this interval. To identify candidate tumor suppressor genes (TSGs), we developed a transcript map of the CDS. The map contains 18 genes and 12 expressed sequence tags/UniGenes. Among the 18 genes are 10 genes that were previously cloned and 8 novel genes. The newly identified genes include CDC23, which encodes a component of the anaphase-promoting complex; RAB6KIFL, which encodes a kinesin-like protein involved in organelle transport; and KLHL3, which encodes a human homologue of the Drosophila ring canal protein, kelch. We determined the intron/exon organization of 14 genes and eliminated each gene as a classical TSG by mutation analysis. In addition, we established a single-nucleotide polymorphism map as well as a map of the mouse genome that is syntenic to the CDS of human 5q31. The development of a transcription map will facilitate the molecular cloning of a myeloid leukemia suppressor gene on 5q.

[Effect of xanthnotoxol on contractility of isolated rabbit ileum]

OBJECTIVE

To study the effect of Xanthnotoxol on contractility of isolated rabbit ileum and its relationship with Ca2+.

METHOD

Routine experimental methods for isolated ileum were adopted.

RESULT

Xanthnotoxol (XT) and Verapamil (Ver) inhibited the contraction of isolated rabbit ileum smooth muscle induced by submaximal concentrations of acetylcholine (ACh) and serotonim (5-TH), with a IC50 value (mumol.L-1) of 10.495 +/- 1.521, 0.428 +/- 0.001 and 18.132 +/- 1.627, 0.249 +/- 0.003, respectively. XT and Ver inhibited the contraction induced by Ca2+ after high K+ depolarization and for noncompetitively antagonist CaCl2 cumulative dose-response curve, the pD'2 value was 4.69 +/- 0.03 and 6.35 +/- 0.10, respectively. XT (10 mumol.L-1) and Ver(0.06 mumol.L-1) inhibited the contraction induced by ACh in Ca(2+)-free medium, while XT (100 mumol.L-1) but not Ver(0.6 mumol.L-1) inhibited the extracellar CA(2+)-dependent contraction induced by ACh.

CONCLUSION

XT has a calcium-antagonistic effect which was not similar to that of Ver.

cDNA cloning and genomic structure of three genes localized to human chromosome band 5q31 encoding potential nuclear proteins

Loss of a whole chromosome 5, or a del(5q), is a recurring abnormality in malignant myeloid diseases. By cytogenetic and molecular analyses, we delineated previously a 1- to 1.5-Mb region that is deleted in all patients with a del(5q). In our efforts to identify a myeloid tumor suppressor gene within the commonly deleted segment (CDS), we have cloned and characterized the genes encoding three putative nuclear proteins, each of which contains a bipartite nuclear localization signal (NLS). In addition, C5ORF5 contains a putative rhoGAP domain at the N-terminus, C5ORF6 has a proline-rich sequence near the N-terminus, and C5ORF7 has a zinc-finger domain that partially overlaps the NLS. All three genes are ubiquitously expressed and encode novel proteins. The C5ORF5 cDNA is 5.47 kb encoding a protein of 915 amino acids (aa) with a predicted molecular mass of approximately 105 kDa. C5ORF5 has 23 exons spanning over 27 kb. The C5ORF6 transcript is 4.1 kb encoding a protein of 392 aa with a predicted molecular mass of approximately 43 kDa. C5ORF6 has 5 exons and spans approximately 11 kb. The C5ORF7 cDNA is 6.3 kb and encodes a protein of 1417 aa with a predicted molecular mass of approximately 155 kDa. C5ORF7 has 24 exons spanning approximately 64 kb. All three genes were localized to the distal half of the CDS between D5S1983 and D5S500. We evaluated each as a candidate tumor suppressor gene by the analysis of myeloid leukemia cells from patients with -5/del(5q), but no inactivating mutations were identified.

Morphological and biochemical assessment of DNA damage and apoptosis in Down syndrome and Alzheimer disease, and effect of postmortem tissue archival on TUNEL

We have previously shown that Alzheimer disease (AD) brain exhibits terminal deoxynucleotidyl transferase dUTP nick end-labeling (TUNEL) for DNA damage and morphological evidence for apoptosis. Down syndrome (DS) is a neurodegenerative disorder that exhibits significant neuropathological parallels with AD. In accordance with these parallels and the need to clarify the mechanism of cell death in DS and AD, we investigated two principal issues in the present study. First, we investigated the hypothesis that TUNEL labeling for DNA damage and morphological evidence for apoptosis is also present in the DS brain. All DS cases employed had a neuropathological diagnosis of AD. Analysis of these cases showed that DS brain exhibits a significant increase in the number of TUNEL-labeled nuclei relative to controls matched for age, Postmortem Delay, and Archival Length, and that a subset of TUNEL-positive nuclei exhibits apoptotic morphologies. We also report that Archival Length in 10% formalin can significantly affect TUNEL labeling in postmortem human brain, and therefore, that Archival Length must be controlled for as a variable in this type of study. Second, we investigated whether biochemical evidence for the mechanism of cell death in DS and AD could be detected. To address this question we employed pulsed-field gel electrophoresis (PFGE) as a sensitive method to evaluate DNA integrity. Although apoptotic oligonucleosomal laddering has not previously been observed in AD, PFGE of DNA from control, DS and AD brain in the present study revealed evidence of high molecular weight DNA fragmentation indicative of apoptosis. This represents biochemical support for an apoptotic mechanism of cell death in DS and AD.

Molecular characterization of KLHL3, a human homologue of the Drosophila kelch gene

The Drosophila kelch protein is a structural component of ring canals and is required for oocyte maturation. Here, we report the cloning and genomic structure of a new human homologue of kelch, KLHL3. At the amino acid level, KLHL3 shares 77% similarity with Drosophila kelch and 89% similarity with Mayven (KLHL2), another human kelch homolog. The approximately 6.5-kb mRNA has a single open reading frame encoding a protein of 587 amino acids with a predicted molecular mass of 650 kDa. Like kelch and KLHL2, the KLHL3 protein contains a poxvirus and zinc finger domain at the N-terminus and six tandem repeats (kelch repeats) at the C-terminus. At least three isoforms, which differ in the length of the N-terminus, are produced and may be the result of alternative promoter usage. We also identified alternative polyadenylation sites and alternative splicing; thus, as many as 12 mRNA variants and six putative protein isoforms could be produced. The KLHL3 gene is mapped to human chromosome 5, band q31, contains 17 exons, and spans approximately 120 kb of genomic DNA. KLHL3 maps within the smallest commonly deleted segment in myeloid leukemias characterized by a deletion of 5q; however, we detected no inactivating mutations of KLHL3 in malignant myeloid disorders with loss of 5q.

cDNA cloning, expression pattern, genomic structure and chromosomal location of RAB6KIFL, a human kinesin-like gene

Kinesin-like proteins are microtubule-associated motors that play important roles in intracellular transport and cell division. We report here the characterization of a new human kinesin-like protein, Rabkinesin6 (RAB6KIFL). The composite cDNA sequence is 2957bp, and encodes a protein of 890 amino acids with a predicted molecular weight of 100kDa. It has high homology (93% similarity) with the mouse kinesin-like protein, Rab6kifl, indicating that it is the human homologue of the mouse gene. RAB6KIFL has all of the structural characteristics required to function as a microtubule-associated motor. Unlike the mouse gene which is ubiquitously expressed, RAB6KIFL expression appears to be tissue specific. It is widely expressed in fetal tissues, abundantly expressed in adult thymus, bone marrow and testis, and is expressed at low levels in heart, placenta and spleen. The RAB6KIFL gene is mapped to human chromosome 5, band q31, spans approximately 8.5kb of genomic DNA, and contains 19 exons. RAB6KIFL maps within the smallest commonly deleted segment in myeloid leukemias characterized by a deletion of 5q; however, we detected no mutations of RAB6KIFL in malignant myeloid disorders with loss of 5q. The description of this human kinesin-like protein may provide a better understanding of the diversity of this large family of proteins.

A third member of the RNA-specific adenosine deaminase gene family, ADAR3, contains both single- and double-stranded RNA binding domains

Members of the double-stranded RNA- (dsRNA) specific adenosine deaminase gene family convert adenosine residues into inosines in dsRNA and are involved in A-to-I RNA editing of transcripts of glutamate receptor (GluR) subunits and serotonin receptor subtype 2C (5-HT(2C)R). We have isolated hADAR3, the third member of this class of human enzyme and investigated its editing site selectivity using in vitro RNA editing assay systems. As originally reported for rat ADAR3 or RED2, purified ADAR3 proteins could not edit GluR-B RNA at the "Q/R" site, the "R/G" site, and the intronic "hot spot" site. In addition, ADAR3 did not edit any of five sites discovered recently within the intracellular loop II region of 5-HT(2C)R RNAs, confirming its total lack of editing activity for currently known substrate RNAs. Filter-binding analyses revealed that ADAR3 is capable of binding not only to dsRNA but also to single-stranded RNA (ssRNA). Deletion mutagenesis identified a region rich in arginine residues located in the N-terminus that is responsible for binding of ADAR3 to ssRNA. The presence of this ssRNA-binding domain as well as its expression in restricted brain regions and postmitotic neurons make ADAR3 distinct from the other two ADAR gene family members, editing competent ADAR1 and ADAR2. ADAR3 inhibited in vitro the activities of RNA editing enzymes of the ADAR gene family, raising the possibility of a regulatory role in RNA editing.

Genomic structure of murine Rab11 family members

Rab11a, Rab11b, and Rab25 in mammals are thought to comprise a subfamily of Rab proteins, although Rab25 has two amino acid differences in its effector domain. We have isolated and characterized the genomic sequences of murine Rab11a and Rab25 and compared them with those of previously characterized mammalian Rab genes. The Rab11a gene spans 29 kb and Rab25 spans 9 kb. The genes have TATA-less promoters, but contain GC-rich areas in their upstream 5' regions. Both genes have 5 exons, with the introns containing characteristic repeats. Rab11a has an unusually long 8. 5-kb fourth intron. The Rab11a and Rab25 genes are localized to chromosomes 9C and 3E3/F1, respectively. The overall organization of the Rab11a, Rab11b, and Rab25 genes is similar, with homologous exon-intron boundaries, and differs markedly from those of Rab3A and Rab1A. These results confirm that Rab11A, Rab11b, and Rab25 represent a closely related gene family.

[Separation of thoracopagus conjoined twins]

OBJECTIVE

To sam up the experience in diagnosis and separation of a thoracopagus conjoined twins.

METHODS

Thoracopagus twin boys were admitted for evaluating possible separation and repair at age of 21 days. X-rays, CT, MRI, and ultrasound scan of torso showed separate and normal gastrointestinal and biliary tracts, little shared vasculature, but shared pericardium, diaphragm and liver parenchyma. The chest junctions were at the sternums and the most inferior two pairs of the ribs. One twin (twin A) had a protruding heart with VSD and ASD.

RESULTS

The infants were separated successfully at age of 45 days. The chest defect of twin A was closed with aid of a polyester pericardial patch graft and a silicon supporter. Managing anesthesia met some difficulty in understanding of the anatomical and physiological consequences of the complex anomaly. They are had brain edema and multiple system organ failures after separation, and were cured under intensive care. They are alive and well 6 months after surgery.

CONCLUSIONS

Careful preoperative evaluation proper anesthesia and surgical technique, and postoperative care are essential to the successful separation of the conjoined twins.

TTID: A novel gene at 5q31 encoding a protein with titin-like features

A deletion of the long arm of chromosome 5 is a recurring abnormality in malignant myeloid disorders. In previous studies, we identified an approximately 1-Mb segment in 5q31 that was deleted in all patients examined. As part of a positional cloning project to identify transcribed sequences in this region, we identified and characterized the TTID gene. This gene contains 10 exons that extend over 19 kb. The composite cDNA is approximately 2.3 kb and encodes a protein of 498 amino acids, with a predicted molecular mass of 55 kDa. The C-terminal half of this putative protein contains an internally repeated domain of 43 amino acids, which resembles the N-terminal half of an immunoglobulin domain from the immense skeletal muscle protein titin. The TTID gene is expressed in multiple muscle tissue types as well as in thyroid gland and bone marrow. We evaluated the gene as a candidate tumor suppressor gene by searching for mutations in malignant myeloid disorders with abnormalities of chromosome 5. However, we detected no inactivating mutations. A single nucleotide change (G to A) was identified at nucleotide position 1889 in the untranslated region of the mRNA, which may represent a polymorphism. Therefore, TTID is unlikely to be the candidate tumor suppressor gene involved in malignant myeloid disorders.

APOE genotype and gender effects on Alzheimer disease in 100 adults with Down syndrome

BACKGROUND

Alzheimer disease (AD) neuropathology is present in Down syndrome (DS) after age 35, but dementia onset varies from ages 40 to 70 years. Because of small sample sizes and nonuniform determination of dementia, previous studies produced differing results on the influence of APOE subtypes on AD in DS.

OBJECTIVE

To determine the influence of the APOE genotype and gender on development of AD in adults with DS to ascertain similarities with AD in the general population.

METHODS

A total of 100 adults with DS (ages 35 to 79 years), almost all of whom were longitudinally assessed by neurologists, underwent APOE genotyping. Dementia onset was determined using criteria applied from the Tenth International Classification of Mental and Behavioral Disorders. This cohort contains the largest number of DS subjects with dementia (n = 57) in a single study, thus increasing reliability of the results.

RESULTS

The epsilon2 allele frequency was 4% in those with dementia versus 13% in those without dementia (p = 0.03); epsilon4 allele frequency was 18% in those with dementia versus 13% in those without dementia (p = 0.45). Using APOE-epsilon3/3 as the reference group, the risk ratio for the development of AD at any given time was 0.34 for the APOE-epsilon2/3 group (p = 0.04) and 1.44 for the APOE-epsilon(3/4,4/4) group (p = 0.25). Women were 1.77 times as likely to dement as men at any given point in time (p = 0.04).

CONCLUSIONS

The epsilon2 allele confers a protective effect, and women with DS have an increased risk for AD, as in the general population. In this sample, epsilon4 does not confer a significantly increased risk for AD in DS.

[Detection of human cytomegalovirus infection in blood donor population by the polymerase chain reaction]

Samples of peripheral blood from 76 different donors were detected for the presence of human cytomegalovirus (HCMV) DNA by polymerase chain reaction (PCR). The results showed that HCMVs were present in 39 out of 76 blood donors which reached an infection positive rate of 51.3%. In addition, the sensitivity and specificity on PCR were tested, it also indicated that the sensitivity can reach the level of 5fg.microliter-1. The method is simple, rapid, highly sensitive and specificity. It can be considered as a diagnostic measure in clinical detection of HCMV.

Human CDC23: cDNA cloning, mapping to 5q31, genomic structure, and evaluation as a candidate tumor suppressor gene in myeloid leukemias

The transition from metaphase to anaphase and exit from mitosis involve the degradation of active cyclin B-CDC2 complexes by ubiquitin-mediated proteolysis. The anaphase-promoting complex (APC) catalyzes the formation of cyclin B-ubiquitin conjugates, thereby targeting cyclin B for degradation. The APC is composed of eight proteins, including four members of a family characterized by multiple tetratricopeptide repeats (TPR). We mapped two overlapping expressed sequence tag clones within a genomic contig on human chromosome 5, band q31. A search revealed high homology to Saccharomyces cerevisiae CDC23, a TPR protein component of the APC. We have isolated the human CDC23 cDNA containing the full-length predicted open reading frame. The approximately 3.3-kb message is ubiquitously expressed and encodes a protein with 591 amino acids (MW = 68,293 Da) and 9 TPR units. The protein has 30% identity and 51% similarity to the S. cerevisiae protein. The human CDC23 gene contains 16 exons and spans approximately 31 kb. CDC23 maps within the smallest commonly deleted segment in myeloid leukemias characterized by a deletion of 5q; however, we detected no mutations of CDC23 in leukemia cells with loss of 5q. Thus, CDC23 is unlikely to be involved in the pathogenesis of myeloid leukemias characterized by abnormalities of chromosome 5.

Dramatic increase of the RNA editing for glutamate receptor subunits during terminal differentiation of clonal human neurons

RNA editing plays an important role in determining physiological characteristics of certain glutamate-gated receptor (GluR) channels such as Ca2+ permeability and desensitization kinetics. In one case, the editing changes a gene-encoded glutamine (Q) to an arginine (R) codon located in the channel-forming domain of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptor subunit GluR-B and also the kainate receptor subunits GluR5 and GluR6. Another case of RNA editing alters an arginine (R) to a glycine (G) codon at a position termed the "R/G" site of AMPA subunits GluR-B, C, and D. Double-stranded RNA-specific adenosine deaminases (DRADA) have been implicated as agents involved in the editing. By using a human teratocarcinoma cell line, NT2, we investigated the change of the RNA editing of GluR subunits in conjunction with the expression of two DRADA members, DRADA1 and DRADA2 genes, during neuronal differentiation. Whereas Q/R and R/G site RNA editing both become progressively activated in differentiating NT2 cells, the expression of the two DRADA genes can already be detected even in the undifferentiated NT2 cells. Development of the editing machinery appears to require, in addition to DRADA enzymes, a currently unidentified mechanism(s) that may become activated during neuronal differentiation.