Mechanism of the extremely high duplex-forming ability of oligonucleotides modified with N-tert-butylguanidine- or N-tert-butyl-N'- methylguanidine-bridged nucleic acids.

Antisense oligonucleotides (ASOs) are becoming a promising class of drugs for treating various diseases. Over the past few decades, many modified nucleic acids have been developed for application to ASOs, aiming to enhance their duplex-forming ability toward cognate mRNA and improve their stability against enzymatic degradations. Modulating the sugar conformation of nucleic acids by substituting an electron-withdrawing group at the 2'-position or incorporating a 2',4'-bridging structure is a common approach for enhancing duplex-forming ability. Here, we report on incorporating an N-tert-butylguanidinium group at the 2',4'-bridging structure, which greatly enhances duplex-forming ability because of its interactions with the minor groove. Our results indicated that hydrophobic substituents fitting the grooves of duplexes also have great potential to increase duplex-forming ability.

Association of mesothelioma deaths with neighborhood asbestos exposure due to a large-scale asbestos-cement plant.

A causal relationship between mesothelioma and occupational asbestos exposure is well known, while some studies have shown a relationship to non-occupational exposures. The aim of this study was to quantify the risk of mesothelioma death associated with neighborhood asbestos exposure due to a large-scale asbestos-cement (AC) plant in Amagasaki, Japan, adjusting properly risk factors including occupational exposures. We conducted a nested case-control study in which a fixed population of 143,929 residents who had been living in Amagasaki City between 1975 and 2002 were followed from 2002 to 2015. All 133 cases and 403 matched controls were interviewed about their occupational, domestic, household, and neighborhood asbestos exposures. Odds ratios (ORs) for mesothelioma death associated with the neighborhood exposure were estimated by a conditional logistic-regression model. For quantitative assessments for neighborhood exposure, we adopted cumulative indices for individuals' residential histories at each residence-specific asbestos concentration multiplied by the duration during the potential exposure period of 1957-1975 (crocidolite). We observed an increasing, dose-dependent risk of mesothelioma death associated with neighborhood exposure, demonstrating that ORs in the highest quintile category were 21.4 (95% confidence interval [CI] 5.8-79.2) for all, 23.7 (95% CI 3.8-147.2) for males, and 26.0 (95% CI 2.8-237.5) for females compared to the lowest quintile, respectively. A quantitative assessment for risk of mesothelioma deaths, adjusting for occupational and non-occupational exposures separately, showed a dose-dependent association with neighborhood exposure and no substantial gender differences in magnitude.

Synthesis and properties of a novel modified nucleic acid, 2'-N-methanesulfonyl-2'-amino-locked nucleic acid.

2'-Amino-locked nucleic acid has a functionalizable nitrogen atom at the 2'-position of its furanose ring that can provide desired properties to a nucleic acid as a scaffold. In this study, we synthesized a novel nucleic acid, 2'-N-methanesulfonyl-2'-amino-locked nucleic acid (ALNA[Ms]) and conducted comparative studies on the physical and pharmacological properties of the ALNA[Ms] and on conventional nucleic acids, such as 2'-methylamino-LNA (ALNA[Me]), which is a classical 2'-amino-LNA derivative, and also on 2',4'-BNA/LNA (LNA). ALNA[Ms] oligomers exhibited binding affinities for the complementary RNA strand that are similar to those of conventional nucleic acids. Four types of ALNA[Ms] nucleosides exhibited no genotoxicity in bacterial reverse mutation assays. The knockdown abilities of Malat1 RNA using the Matat1 antisense oligonucleotide (ASO) containing ALNA[Ms] were higher than those of ALNA[Me] and were closer to those of LNA. Furthermore, the ASO containing ALNA[Ms] showed different tissue tropism from that containing LNA. ALNA[Ms] exhibited biological activities that were distinct from conventional constrained nucleic acids, suggesting the possibility that ALNA[Ms] can serve as novel modified nucleic acids in oligonucleotide therapeutics.

2'-N-Alkylaminocarbonyl-2'-amino-LNA: Synthesis, duplex stability, nuclease resistance, and in vitro anti-microRNA activity.

2'-Amino-LNA has the potential to acquire various functions through chemical modification at the 2'-nitrogen atom. This study focused on 2'-N-alkylaminocarbonyl 2'-amino-LNA, which is a derivative of 2'-amino-LNA. We evaluated its practical usefulness as a chemical modification of anti-miRNA oligonucleotide. The synthesis of phosphoramidites of 2'-N-alkylaminocarbonyl substituted 2'-amino-LNA bearing thymine and 5-methylcytosine proceeded in good yields. Incorporating the 2'-N-alkylaminocarbonyl-2'-amino-LNA monomers into oligonucleotides improved the duplex stability for complementary RNA strands and robust nuclease resistance. Moreover, 2'-N-alkylaminocarbonyl-2'-amino-LNA is a promising scaffold that significantly increases the potency of anti-miRNA oligonucleotides.

Synthesis and properties of oligonucleotides modified with an N-methylguanidine-bridged nucleic acid (GuNA[Me]) bearing adenine, guanine, or 5-methylcytosine nucleobases.

Chemical modifications have been extensively used for therapeutic oligonucleotides because they strongly enhance the stability against nucleases, binding affinity to the targets, and efficacy. We previously reported that oligonucleotides modified with an N-methylguanidine-bridged nucleic acid (GuNA[Me]) bearing the thymine (T) nucleobase show excellent biophysical properties for applications in antisense technology. In this paper, we describe the synthesis of GuNA[Me] phosphoramidites bearing other typical nucleobases including adenine (A), guanine (G), and 5-methylcytosine (mC). The phosphoramidites were successfully incorporated into oligonucleotides following the method previously developed for the GuNA[Me]-T-modified oligonucleotides. The binding affinity of the oligonucleotides modified with GuNA[Me]-A, -G, or -mC toward the complementary single-stranded DNAs or RNAs was systematically evaluated. All of the GuNA[Me]-modified oligonucleotides were found to have a strong affinity for RNAs. These data indicate that GuNA[Me] could be a useful modification for therapeutic antisense oligonucleotides.

Synthesis and properties of GuNA purine/pyrimidine nucleosides and oligonucleotides.

We recently designed guanidine-bridged nucleic acids (GuNA), and GuNA bearing a thymine (T) nucleobase was synthesized and successfully incorporated into oligonucleotides. The GuNA-T-modified oligonucleotides possessed high duplex-forming ability towards their complementary single-stranded RNAs and were highly stable against 3'-exonuclease. Therefore, GuNA is a promissing artificial nucleic acid for therapeutic antisense oligonucleotides. We herein report the facile synthesis of GuNA phosphoramidites bearing adenine (A), guanine (G), and 5-methylcytosine (mC) nucleobases and a robust method for the preparation of GuNA-modified oligonucleotides, even with sequences having acid-sensitive purine nucleobases. Oligonucleotides modified with GuNA-A, -G, or -mC possessed high duplex-forming ability, similar to those modified with GuNA-T. Moreover, some of the GuNA-modified oligonucleotides were revealed to have high base discriminating ability compared with that of their natural counterparts. GuNA nucleosides exhibited no genotoxicity in bacterial reverse mutation assays. Thus, all GuNAs (GuNA-T, -A, -G, and -mC) are now available to be examined in therapeutic applications.

Facile synthesis and fundamental properties of an N-methylguanidine-bridged nucleic acid (GuNA[NMe]).

An N-methylguanidine-bridged nucleic acid (GuNA[NMe]), a guanidine-bridged nucleic acid (GuNA) bearing a methyl substituent at the bridge, was successfully synthesised and incorporated into oligonucleotides. By employing an acetyl protecting group, GuNA[NMe]-modified oligonucleotides bearing acid-sensitive purine nucleobases were successfully prepared. The obtained GuNA[NMe]-modified oligonucleotides exhibit excellent binding affinity towards the complementary single-stranded RNA and DNA. Furthermore, even a single GuNA[NMe] modification provides robust enzymatic stability, similar to that achieved by the well-established phosphorothioate backbone modification. These data indicate that such a GuNA[NMe] represents a valuable modification for the development of therapeutic oligonucleotides.

Relationship between cumulative exposure to 1,2-dichloropropane and incidence risk of cholangiocarcinoma among offset printing workers.

OBJECTIVES: This study aimed to evaluate the relationship between cumulative exposure to 1,2-dichloropropane (1,2-DCP) and incidence risk of cholangiocarcinoma among workers in the offset proof-printing section of a small printing company in Osaka, Japan. METHODS: We identified 95 workers of a printing company (78 men and 17 women) who had been exposed to 1,2-DCP between 1987 and 2006, and calculated the standardised incidence ratio (SIR) of cholangiocarcinoma from 1987 to 2012. We estimated cumulative exposure to 1,2-DCP and calculated SIRs in four exposure categories. We also calculated incidence rate ratios (RRs) adjusted by sex, age, calendar year and dichloromethane (DCM) exposure for three exposure categories using Poisson regression analysis. RESULTS: Cumulative exposures to 1,2-DCP ranged from 32 to 3433 ppm-years (mean, 851 ppm-years) and the SIR was 1171 (95% CI 682 to 1875). In the analysis of the four exposure categories, SIRs increased significantly in the three highest exposure categories, but not in the lowest category. Adjusted RRs in the middle and high exposure categories were 14.9 (95% CI 4.1 to 54.3) and 17.1 (95% CI 3.8 to 76.2), respectively, in the analysis without lag time, and were 11.4 (95% CI 3.3 to 39.6) and 32.4 (95% CI 6.4 to 163.9), respectively, in the analysis with a 5-year lag. The trend analysis revealed a significant increase in RR in association with increasing cumulative exposure to 1,2-DCP. DCM exposure was not significantly associated with the development of cholangiocarcinoma. CONCLUSIONS: The present study demonstrated an exposure-response relationship between exposure to 1,2-DCP and the development of cholangiocarcinoma.

Screening and surveillance for occupational cholangiocarcinoma in workers exposed to organic solvents.

PURPOSE: This study aimed to establish an efficient strategy for screening and surveillance for occupational cholangiocarcinoma. METHODS: We evaluated the consecutive changes in laboratory findings during regular health examinations and in abdominal ultrasonography findings before the diagnosis of occupational cholangiocarcinoma in nine patients. The results of laboratory tests and abdominal ultrasonography at the time of diagnosis were also examined. RESULTS: In all patients, the serum γ-glutamyl transpeptidase (γ-GTP) activity increased several years before the diagnosis of cholangiocarcinoma. The serum alanine aminotransferase (ALT) activity also increased several years before the diagnosis, following an increase in the serum aspartate aminotransferase (AST) activity in most patients. Abdominal ultrasonography before the diagnosis revealed regional dilatation of the bile ducts, which continued to enlarge. At the time of diagnosis, the γ-GTP, AST, and ALT activities were increased in nine, seven, and seven patients, respectively. The regional dilatation of bile ducts without tumor-induced stenosis, dilated bile ducts due to tumor-induced stenosis, space-occupying lesions, and/or lymph node swelling were observed. The serum concentrations of carbohydrate antigen 19-9 (CA 19-9) and/or carcinoembryonic antigen (CEA) were increased in all patients. CONCLUSIONS: Regular health examinations with a combination of ultrasonography and laboratory tests including the γ-GTP, AST, ALT, CA 19-9, and CEA levels are useful for screening and surveillance for occupational cholangiocarcinoma.

[Cholangiocarcinoma among printing workers].

By June 2013, seventeen workers had suffered from intrahepatic or extrahepatic bile duct cancer (cholangiocarcinoma) in an offset proof-printing company in Osaka and nine of the workers had died. Ages at diagnosis were 25 to 45 years old. Known risk factors for cholangiocarcinoma were not found in the patients. All of the patients were exposed to 1,2-dichloropropane at high level for long-term and were diagnosed with cholangiocarcinoma 7 to 20 years after the first exposure. Twelve of the patients were also exposed to dichloromethane. The Japan Ministry of Health, Labour and Welfare recognized the cancer to be an occupational disease.

Cholangiocarcinoma among offset colour proof-printing workers exposed to 1,2-dichloropropane and/or dichloromethane.

OBJECTIVES: The present study was conducted to investigate the relationship between occupational chemical exposure and incidence of cholangiocarcinoma among workers in the offset colour proof-printing section of a small printing company in Osaka, Japan. METHODS: We identified 51 men who had worked in the proof-printing room, and 11 men who had worked in the front room for at least 1 year between 1991 and 2006. We interviewed them about the chemicals they used, and estimated their levels of exposure to chemicals. We also investigated the medical records of 11 cholangiocarcinoma patients, and calculated the standardised mortality ratio (SMR) from 1991 to 2011. RESULTS: Workers used 1,2-dichloropropane (1,2-DCP) from approximately 1985 to 2006, and dichloromethane (DCM) from approximately 1985 to 1997/1998. Exposure concentrations were estimated to be 100-670 ppm for 1,2-DCP and 80-540 ppm for DCM among the proof-printing workers. All 11 patients were pathologically diagnosed with cholangiocarcinoma. Ages at diagnosis were 25-45 years, and ages at death were 27-46 years among the six deceased individuals. The primary cancer site was the intrahepatic bile duct for five patients, and the extrahepatic bile ducts for six. All patients were exposed to 1,2-DCP for 7-17 years and diagnosed with cholangiocarcinoma 7-20 years after their first exposure. Ten patients were also exposed to DCM for 1-13 years. The SMR for cholangiocarcinoma was 2900 (expected deaths: 0.00204, 95% CI 1100 to 6400) for all workers combined. CONCLUSIONS: These findings suggest that 1,2-DCP and/or DCM may cause cholangiocarcinoma in humans.

Association between occupational exposure and control measures for antineoplastic drugs in a pharmacy of a hospital.

OBJECTIVES: To investigate the association between occupational contamination and exposure levels to antineoplastic drugs and the application of control measures in a hospital work environment. METHODS: Wipe samples of equipments were collected at a hospital in Osaka Prefecture, Japan, from 2007 to 2011. These samples were subjected to measurements of cyclophosphamide (CP), gemcitabine (GEM), platinum-containing drugs (Pt), and fluorouracil (5FU). Additionally, 24-h urine samples were collected from pharmacists who handled antineoplastic drugs, which were analyzed for CP and alpha-fluoro-beta-alanine (AFBA). The application of control measures was scored according to a checklist, which consisted of the following five items: safety equipment and maintenance, training and documentation, devices for safe handling, personal protective equipment, and emergency care. The aim was to obtain a score of 80%. RESULTS: The median CP, GEM, and 5FU concentrations of all wipe samples were significantly lower during the period when the mean score was >80% (attainment period) versus when the mean score was ≤80% (nonattainment period; all P < 0.001, Mann-Whitney's U-test). Additionally, the median urinary CP and AFBA concentrations of pharmacists during the attainment period tended to be lower than that of those during the nonattainment period (P = 0.061 and 0.061, respectively, using Mann-Whitney's U-test). CONCLUSIONS: Contamination and levels of exposure to antineoplastic drugs decreased with a score higher than 80%. The scores of the items on the checklist appeared to adequately reflect the condition of the control measures, as increases in all five items were associated with reductions in the contamination by and levels of exposure to all drugs.

A Systemically Administered Unconjugated Antisense Oligonucleotide Targeting DUX4 Improves Muscular Injury and Motor Function in FSHD Model Mice.

Facioscapulohumeral muscular dystrophy (FSHD), one of the most common muscular dystrophies, is caused by an abnormal expression of the DUX4 gene in skeletal muscles, resulting in muscle weakness. In this study, we investigated MT-DUX4-ASO, a novel gapmer antisense oligonucleotide (ASO). MT-DUX4-ASO decreased the expression of DUX4 and its target genes in FSHD patient-derived myoblasts. For the first time, we demonstrated that a systemically administered ASO, even without a ligand for drug delivery, could significantly improve muscle injury and motor function in the ACTA1-MCM/FLExDUX4 (DUX4-TG) mouse model of FSHD. Tamoxifen (TMX) injection transiently induces skeletal-muscle-specific DUX4 expression in DUX4-TG mice, while the skeletal muscles of TMX-untreated DUX4-TG mice have leaky DUX4 expression in a small subset of myofibers similar to those of FSHD patients. Subcutaneous 10 mg/kg of MT-DUX4-ASO at two-week intervals significantly suppressed muscular DUX4 target gene expression, histological muscle injury, and blood muscle injury marker elevation in TMX-untreated DUX4-TG mice. Notably, MT-DUX4-ASO at 10 mg/kg every other week significantly prevented the TMX-induced declines in treadmill test running speed and muscle force in DUX4-TG mice. Thus, the systemically administered unconjugated MT-DUX4-ASO suppressed disease progression in DUX4-TG mice, extending the potential of unconjugated ASOs as a promising FSHD treatment strategy.

Structure-Activity Relationships of Anti-microRNA Oligonucleotides Containing Cationic Guanidine-Modified Nucleic Acids.

Anti-microRNA oligonucleotides (AMOs) are valuable tools for the treatment of diseases caused by the dysregulation of microRNA expression. However, the correlation between chemical modifications in AMO sequences and the microRNA-inhibitory activity has not been fully elucidated. In this study, we synthesized a series of AMOs containing cationic guanidine-bridged nucleic acids (GuNA) and evaluated their activities using a dual luciferase assay. We also optimized the site of GuNA substitution and found an effective design for the inhibition of microRNA-21, which was partially different from that of conventional nucleic acid derivatives. This study showed that GuNA-substituted AMOs are effective in inhibiting the function of microRNA.

An updated historical cohort mortality study of workers exposed to asbestos in a refitting shipyard, 1947-2007.

PURPOSE: To evaluate the long-term health effects of occupational asbestos exposure, an updated historical cohort mortality study of workers at a refitting shipyard was undertaken. METHODS: The cohort consisted of 249 male ship repair workers (90 laggers, 159 boiler repairers). To determine relative excess mortality, standardized mortality ratios (SMRs) were calculated using mortality rates among the Japanese male population. Mortality follow-up of study subjects was performed for the period from 1947 till the end of 2007. RESULTS: We identified the vital status of 87 (96.7%) laggers and 150 (94.3%) boiler repairers. Of these, 63 (72.4%) and 95 (63.3%), respectively, died. Laggers, who had handled asbestos materials directly, showed a significantly elevated SMR of 2.64 (95% confidence interval [CI]: 1.06-5.44) for lung cancer and 2.49 (95% CI: 1.36-4.18) for nonmalignant respiratory diseases. Boiler repairers, who had many opportunities for secondary exposure to asbestos and a few for direct exposure, showed no significant elevation in SMR for lung cancer but a significantly elevated SMR of 1.78 (95% CI: 1.06-2.81) for nonmalignant respiratory diseases. In an analysis according to duration of employment, there was a significantly elevated SMR of nonmalignant respiratory diseases in the longer working years group. Among workers from both jobs, no deaths caused by mesothelioma in addition to those in the original study were found and no subject died from larynx cancer. CONCLUSION: This updated study confirmed a significant excess of asbestos-related mortality from diseases such as lung cancer and nonmalignant respiratory diseases among workers in a refitting shipyard in Japan.

Association between occupational exposure levels of antineoplastic drugs and work environment in five hospitals in Japan.

PURPOSE: The aim of the present study was to evaluate the measurement of contamination by antineoplastic drugs for safer handling of such drugs by medical workers. We investigated the relationship between the contamination level of antineoplastic drugs and the conditions of their handling. METHODS: Air samples and wipe samples were collected from equipment in the preparation rooms of five hospitals (hospitals A-E). These samples were subjected to measurement of the amounts of cyclophosphamide (CPA), fluorouracil (5FU), gemcitabine (GEM), and platinum-containing drugs (Pt). Twenty-four-hour urine samples were collected from the pharmacists who handled or audited, the antineoplastic drugs were analyzed for CPA and Pt. RESULTS: Pt was detected from air samples inside BSC in hospital B. Antineoplastic drugs were detected from wipe samples of the BSC in hospitals A, B, D, and E and of other equipment in the preparation rooms in hospitals A, B, C, and D. Cyclophosphamide and 5FU were detected from wipe samples of the air-conditioner filter in hospital A, and CPA was detected from that in hospital D. Cyclophosphamide was detected from urine samples of workers in hospitals B, D, and E. CONCLUSION: The contamination level of antineoplastic drugs was suggested to be related with the amount of drugs handled, cleaning methods of the equipment, and the skill level of the technique of maintaining negative pressure inside a vial. In order to reduce the contamination and exposure to antineoplastic drugs in the hospital work environment very close to zero, comprehensive safety precautions, including adequate mixing and cleaning methods was required in addition to BSC and closed system device.

Increased risk of lung cancer mortality among residents near an asbestos product manufacturing plant.

We investigated whether individuals exposed to asbestos by living near an asbestos-manufacturing facility experienced increased lung cancer mortality. We studied a neighborhood around such a plant in the central Japanese city of Hashima. From 1943 to 1991 this plant produced insulation and packing material using amosite- and chrysotile-type asbestos fibers. The study group was comprised of 577 households. We obtained demographic information by a questionnaire and determined the underlying cause of death for deceased household members from death certificates. Using hourly meteorological data from local observatories, we estimated relative asbestos concentrations in the plant's vicinity, determined the quartile boundaries, and designated each study subject's quartile of ambient exposure. Finally, we calculated standardized mortality ratios to evaluate the association of residential asbestos with lung cancer risk. Our findings strongly suggest that neighborhood asbestos exposure can increase the risk of lung cancer mortality in men and probably in women.

Mapping the risk of mesothelioma due to neighborhood asbestos exposure.

RATIONALE: Little is known about neighborhood exposure to asbestos and mesothelioma risk among residents around an industrial source of asbestos. OBJECTIVES: To investigate the magnitude of the risk among residents by asbestos exposure levels and to determine the range of the area affected by asbestos. METHODS: We calculated standardized mortality ratios of mesothelioma from 1995 to 2006 among the estimated population at risk that lived around a former large asbestos cement pipe plant in Amagasaki City, Japan, between 1957 and 1975, the time when the plant had used crocidolite and chrysotile. The distance between the plant and homes and relative asbestos concentrations obtained by diffusion equations involving meteorological conditions were used to determine asbestos exposure levels among residents. MEASUREMENTS AND MAIN RESULTS: We identified 73 mesothelioma deaths of 35 men and 38 women who had no occupational exposure to asbestos. Among persons who had lived within a 300-m radius of the plant, the standardized mortality ratio of mesothelioma was 13.9 (95% confidence interval, 5.6-28.7) for men and 41.1 (95% confidence interval, 15.2-90.1) for women. When the study area was divided into five regions by relative asbestos concentration, standardized mortality ratios of mesothelioma declined, for both sexes, in a linear dose-dependent manner with concentration. The regions with a significantly elevated standardized mortality ratio reached 2,200 m from the plant in the same direction in which the wind predominantly blew. CONCLUSIONS: Neighborhood exposure to asbestos can pose a serious risk to residents across a wide area.

Use of a closed system device to reduce occupational contamination and exposure to antineoplastic drugs in the hospital work environment.

OBJECTIVES: The aim of the preset study was to evaluate the applicability of a closed system device to protect against occupational contamination and exposure to antineoplastic drugs in the work environment of a hospital. METHODS: We compared the contamination by and exposure to cyclophosphamide (CPA) between a conventional mixing method and a mixing method using a closed system device. Wipe samples in the preparation room, gloves samples and 24-h urine samples of pharmacists preparing antineoplastic drugs were collected. Working surfaces inside the biological safety cabinet (BSC), front side of the air grilles of the BSC, stainless steel trays, working table and floor were wiped. At first, sample collection was done on 5 days over an interval of 2 weeks using the conventional mixing method. After 2 weeks training for using the closed system device, sample collection was done 5 days over an interval of 2 weeks using the closed system device. RESULTS: When pharmacists prepared antineoplastic drugs by the conventional method, CPA was detected from all wipe samples, and the mean and median concentrations of CPA were 1.0 and 0.16 ng cm(-2), respectively (range was from 0.0095 to 27 ng cm(-2)). When pharmacists prepared antineoplastic drugs with a closed system device, CPA was detected from 75% of the wipe samples at mean and median concentrations of 0.18 and 0.0013 ng cm(-2), respectively (the range was from lower than detection limit to 4.4 ng cm(-2)). Using the closed system device significantly reduced the surface contamination of CPA for all wipe sampling points in the preparation room (Mann-Whitney's U-test). The range of CPA of glove samples used in the conventional method and closed system device ranged from lower than detection limit to 3200 ng per glove-pair and from lower than detection limit to 740 ng per glove-pair, respectively. Using the closed system device significantly reduced the gloves contamination of CPA (Mann-Whitney's U-test). The range of urinary CPA of six pharmacists preparing the antineoplastic drugs with the conventional method and closed system device ranged from lower than detection limit to 170 ng day(-1) and from lower than detection limit to 15 ng day(-1), respectively. Using the closed system device significantly reduced the amount of urinary CPA in pharmacists preparing the antineoplastic drugs (Wilcoxon's signed ranks test). CONCLUSIONS: We concluded that a closed system device can reduce occupational contamination and exposure to antineoplastic drugs in the hospital work environment.