Enhancement of target specificity of CRISPR-Cas12a by using a chimeric DNA-RNA guide.

The CRISPR-Cas9 system is widely used for target-specific genome engineering. CRISPR-Cas12a (Cpf1) is one of the CRISPR effectors that controls target genes by recognizing thymine-rich protospacer adjacent motif (PAM) sequences. Cas12a has a higher sensitivity to mismatches in the guide RNA than does Cas9; therefore, off-target sequence recognition and cleavage are lower. However, it tolerates mismatches in regions distant from the PAM sequence (TTTN or TTN) in the protospacer, and off-target cleavage issues may become more problematic when Cas12a activity is improved for therapeutic purposes. Therefore, we investigated off-target cleavage by Cas12a and modified the Cas12a (cr)RNA to address the off-target cleavage issue. We developed a CRISPR-Cas12a that can induce mutations in target DNA sequences in a highly specific and effective manner by partially substituting the (cr)RNA with DNA to change the energy potential of base pairing to the target DNA. A model to explain how chimeric (cr)RNA guided CRISPR-Cas12a and SpCas9 nickase effectively work in the intracellular genome is suggested. Chimeric guide-based CRISPR- Cas12a genome editing with reduced off-target cleavage, and the resultant, increased safety has potential for therapeutic applications in incurable diseases caused by genetic mutations.

Desmoplastic fibroblastoma mimicking tenosynovial giant cell tumor encasing a tendon of the foot.

Desmoplastic fibroblastoma is an uncommon, benign fibrous soft tissue tumor that usually occurs in the arms, shoulders, neck, hands, and feet in the fifth to seventh decades of life. In general, it is commonly located in the subcutaneous tissue and skeletal muscle. The authors report an unusual case of a desmoplastic fibroblastoma mimicking tenosynovial giant cell tumor encasing a tendon of the foot in a 72-year-old woman. Ultrasonography revealed an inhomogeneously hypoechoic lobulated soft tissue lesion completely wrapped around the extensor digitorum longus tendon. Color Doppler study revealed increased vascularity in the internal and peripheral portions of the lesion. Magnetic resonance imaging revealed a well-defined, lobulated soft tissue mass encasing the extensor digitorum longus tendon with predominantly isointense signal with some areas of hypointense signal on T1-weighted images, predominantly hyperintense signal with some areas of hypointense signal on T2-weighted images, and inhomogeneous enhancement on fat-suppressed contrast-enhanced T1-weighted images. Surgical excision was performed, and the mass was diagnosed on pathological examination as a desmoplastic fibroblastoma. There has been no previously published radiologic case of a desmoplastic fibroblastoma encasing a tendon of the foot in the literature.

Extensive spinal extradural ganglioneuroma of the lumbar spine: mimicking lymphoma.

BACKGROUND: Ganglioneuromas are rare, benign, well-differentiated tumors arising from neural crest cells that commonly occur in the posterior mediastinum, retroperitoneum, cervical spine, and adrenal gland. We report an unusual case of an extensive spinal extradural ganglioneuroma, circumferentially and longitudinally affecting the extradural space of the lumbar spine and continuously invading bilateral psoas muscles. CASE DESCRIPTION: A 32-year-old man presented with a 1-week history of abdominal pain and diarrhea. Radiographs revealed scalloping of the posterior surfaces of the L2 and L3 vertebral bodies and widening of L2-3 and L3-4 bilateral intervertebral foramina. Computed tomography scans and magnetic resonance imaging showed a well-defined lobulated extradural mass from L1 to L4 and a continuously forming mass in the psoas muscles through L2-3 bilateral neural foramina. The mass demonstrated homogeneously isointense signal on T1-weighted images, inhomogeneously hyperintense-to-isointense signal on T2-weighted images, and inhomogeneous enhancement on fat-suppressed contrast-enhanced T1-weighted images. Radiologic diagnosis included spinal epidural lymphoma. Percutaneous biopsy with sonographic guidance was performed, and the mass was diagnosed on pathological examination as a ganglioneuroma. CONCLUSIONS: This is the first known reported case in the literature of a spinal extradural ganglioneuroma with circumferentially and longitudinally extensive involvement of the extradural space and a large psoas mass.

Comparison of a split-dose bowel preparation with 2 liters of polyethylene glycol plus ascorbic acid and 1 liter of polyethylene glycol plus ascorbic acid and bisacodyl before colonoscopy.

BACKGROUND AND AIMS: Recently, a low-volume polyethylene glycol formulation containing ascorbic acid (PEG-Asc) has proven as safe and effective as traditional 4-L PEG solutions for colonoscopy preparation. However, currently available aqueous purgative formulations are poorly tolerated. The aim of this study was to compare a split-dose 2-L PEG-Asc formulation and a 1-L PEG-Asc formulation with bisacodyl (10 mg) to determine the quality of bowel cleansing and patient tolerability. METHODS: A single-center, randomized, observer-blinded study was performed between May 2015 and September 2015. Two hundred outpatients referred for colonoscopy were prospectively enrolled and assigned to either the split-dose 2-L PEG-Asc group or the 1-L PEG-Asc with bisacodyl 10-mg group. The Boston Bowel Preparation Scale (BBPS) and Aronchick Bowel Preparation Scale (ABPS) were used to evaluate bowel cleansing. The tolerability of the regimens and satisfaction of patients was determined based on a questionnaire. RESULTS: Two hundred patients received either 2-L PEG-Asc or 1-L PEG-Asc with bisacodyl. Regarding colon cleansing outcome (BBPS and ABPS), the 1-L PEG-Asc with bisacodyl group showed similar but non-inferior results compared with the 2-L PEG-Asc group on both BBPS (6.92 ± 1.63 vs 6.57 ± 1.37; P = .103) and ABPS (96% vs 95%; P = 1.000) scales. Tolerability was similar for both 1-L PEG-Asc with bisacodyl and 2-L PEG-Asc. CONCLUSIONS: 1-L PEG-Asc is a suitable alternative to low-volume bowel preparation for colonoscopy. Our study showed that the 1-L PEG-Asc plus bisacodyl preparation has comparable tolerability and results in adequate colon cleansing. Bowel preparation with bisacodyl and 1-L PEG-Asc is a suitable alternative to low-volume bowel preparation for colonoscopy. (Clinical trial registration number: NCT02980562.).

Scaled Signal Intensity of Uterine Fibroids on T2-Weighted MR Imaging as a Predictor of the Potential Response to Uterine Fibroid Embolization.

PURPOSE: To determine feasibility of scaled signal intensity (SSI) of uterine fibroids on T2-weighted magnetic resonance (MR) images to predict volume reduction rate (VRR) after uterine fibroid embolization (UFE). MATERIALS AND METHODS: In this retrospective study, 66 premenopausal women underwent UFE. Patients underwent follow-up MR imaging 3 months after UFE. SSI of predominant fibroids was measured on T2-weighted MR images obtained before the procedure by standardizing the mean signal intensity to a 0-to-100 scale, with 0 representing rectus abdominis muscle and 100 representing subcutaneous fat (100) for reference values. RESULTS: VRR of predominant fibroids was 12.3%-99.0% (mean 53.7%). SSI of predominant fibroids was 0.9-73.6 (mean 24.6). SSI was significantly related to VRR of fibroids (P < .01). The optimal SSI cutoff value to predict VRR > 50% was 18.16 with sensitivity of 78.8% and specificity of 66.7%. The optimal SSI cutoff value to predict VRR < 30% was 14.38 with sensitivity of 75% and specificity of 70.7%. CONCLUSIONS: SSI of fibroids was significantly related to fibroid VRR after UFE. SSI may be useful in the quantified prediction of volume reduction.

A case of Mayer-Rokitansky-Küster-Hauser syndrome presenting as Graves disease.

The Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome is a congenital disorder characterized by aplasia of the uterus and the upper part of the vagina in an XX individual with normal development of secondary sexual characteristics. Individuals with this syndrome may also present with renal and skeletal abnormalities. We report a case of a 16-year-old girl presenting with thyrotoxicosis and primary amenorrhea. After being diagnosed with Graves disease, this patient was placed on antithyroid medication. Although her thyroid function normalized, she did not start to menstruate. Therefore, we assessed her primary amenorrhea and diagnosed the patient with MRKH syndrome through pelvic imaging. To our knowledge, an association between Graves disease and MRKH syndrome has not yet been reported.

Prediction-based highly sensitive CRISPR off-target validation using target-specific DNA enrichment.

CRISPR effectors, which comprise a CRISPR-Cas protein and a guide (g)RNA derived from the bacterial immune system, are widely used for target-specific genome editing. When the gRNA recognizes genomic loci with sequences that are similar to the target, deleterious mutations can occur. Off-target mutations with a frequency below 0.5% remain mostly undetected by current genome-wide off-target detection techniques. Here we report a method to effectively detect extremely small amounts of mutated DNA based on predicted off-target-specific amplification. In this study, we used various genome editors to induce intracellular genome mutations, and the CRISPR amplification method detected off-target mutations at a significantly higher rate (1.6~984 fold increase) than an existing targeted amplicon sequencing method. In the near future, CRISPR amplification in combination with genome-wide off-target detection methods will allow detection of genome editor-induced off-target mutations with high sensitivity and in a non-biased manner.

Improving of bowel cleansing effect for polyethylene glycol with ascorbic acid using simethicone: A randomized controlled trial.

BACKGROUND AND AIM: Low-volume polyethylene glycol with ascorbic acid (PEG-Asc) use is reported to be as safe and effective as traditional 4-L polyethylene glycol use. However, PEG-Asc produces bubbles, which cause problems during colonoscopy. Data on the effects of using antifoaming agents such as simethicone with PEG-Asc are lacking. The aim of this CONSORT-prospective, randomized, observer-blinded, controlled trial is to compare the quality of bowel preparation and compliance between PEG-Asc users and PEG-Asc plus simethicone users. METHODS: Adult outpatients aged 18 to 80 years undergoing colonoscopy were recruited to the study. Two hundred sixty patients were randomly assigned to 1 of 2 treatment arms, PEG-Asc or PEG-Asc plus simethicone. The primary outcome measure was the bowel cleansing quality using Boston bowel preparation scale and bubble scores. The secondary outcome measures were patient tolerability and doctor tolerability. RESULTS: The simethicone group showed superior cleansing results (6-9 Boston scale scores: 99% vs. 84%, <5% bubble scores: 96% vs. 49%, P < 0.001) and fewer gastrointestinal symptoms (abdominal fullness: 24% vs. 55%, colicky pain: 5% vs. 24%, P < 0.001) than the non-simethicone group. Moreover, endoscopist fatigue during colonoscopy was lower in the simethicone group than in the non-simethicone group (1.31 ±â€Š0.75 vs. 2.97 ±â€Š2.14, P < 0.001). CONCLUSION: PEG-Asc plus simethicone use was more effective and associated with better patient and endoscopist tolerance than PEG-Asc use. Therefore, this combination is recommended as one of the promising methods for bowel preparation before colonoscopy.

Discharge hemoglobin and outcome in patients with acute nonvariceal upper gastrointestinal bleeding.

BACKGROUND AND STUDY AIMS: Many patients with acute gastrointestinal bleeding present with anemia and frequently require red blood cell (RBC) transfusion. A restrictive transfusion strategy and a low hemoglobin (Hb) threshold for transfusion had been shown to produce acceptable outcomes in patients with acute upper gastrointestinal bleeding. However, most patients are discharged with mild anemia owing to the restricted volume of packed RBCs (pRBCs). We investigated whether discharge Hb influences the outcome in patients with acute nonvariceal upper gastrointestinal bleeding. PATIENTS AND METHODS: We retrospectively analyzed patients with upper gastrointestinal bleeding who had received pRBCs during hospitalization between January 2012 and January 2014. Patients with variceal bleeding, malignant lesion, stroke, or cardiovascular disease were excluded. We divided the patients into 2 groups, low (8 g/dL ≤ Hb < 10 g/dL) and high (Hb ≥ 10 [g/dL]) discharge Hb, and compared the clinical course and Hb changes between these groups. RESULTS: A total of 102 patients met the inclusion criteria. Fifty patients were discharged with Hb levels < 10 g/dL, whereas 52 were discharged with Hb levels > 10 g/dL. Patients in the low Hb group had a lower consumption of pRBCs and shorter hospital stay than did those in the high Hb group. The Hb levels were not fully recovered at outpatient follow-up until 7 days after discharge; however, most patients showed Hb recovery at 45 days after discharge. The rate of rebleeding after discharge was not significantly different between the 2 groups. CONCLUSIONS: In patients with acute upper gastrointestinal bleeding, a discharge Hb between 8 and 10 g/dL was linked to favorable outcomes on outpatient follow-up. Most patients recovered from anemia without any critical complication within 45 days after discharge.

Identification of rat urinary and fecal metabolites of a new herbicide, pyribenzoxim.

Rats were treated with pyribenzoxim (O-[2,6-bis[(4,6-dimethoxy-2-pyrimidinyl)oxy]benzoyl]oxime), a new herbicide, to investigate the related metabolites in urine and feces. Metabolites were identified using LC/MS (electrospray ionization) and GC/MS (electron impact ionization) following the relatively simple and rapid extraction and purification procedures. Three metabolites were identified in urine either from oral gavage or intravenous (iv) injection. They were benzophenone oxime (BO), benzophenone oxime glucuronide (BOG), and 2-hydroxy-6-(4,6-dimethoxypyrimidin-2-yloxy)benzoic acid (HDB). Benzophenone oxime was present in larger quantity than BOG and HDB in urine from oral treatment, while the case was opposite in urine from iv treatment. Glucuronide conjugate was confirmed unambiguously by enzyme hydrolysis. 2,6-Bis(4,6-dimethoxypyrimidin-2-yloxy)benzoic acid (KIH-2023) and benzophenone were identified in feces. Benzophenone was confirmed by GC/MS and HPLC/DAD since LC/MS could not produce an ESI spectrum. On the basis of the results obtained, a metabolic map of pyribenzoxim is proposed.

Fatal Breakthrough Mucormycosis in an Acute Myelogenous Leukemia Patient while on Posaconazole Prophylaxis.

Posaconazole is a new oral triazole with broad-spectrum antifungal activity. Posaconazole has also shown a significant advantage of preventing invasive fungal infection compared to fluconazole or itraconazole in patients with prolonged neutropenia. Indeed, posaconazole has been commonly used for antifungal prophylaxis in patients undergoing remission induction chemotherapy for acute myelogenous leukemia or myelodysplastic syndrome. We experienced a case of fatal mucormycosis despite posaconazole prophylaxis. To our knowledge, this is the first reported case of fatal breakthrough mucormycosis in a patient receiving posaconazole prophylaxis during remission induction chemotherapy in Korea. This case demonstrated that breakthrough fungal infection can occurs in patients receiving posaconazole prophylaxis because of its limited activity against some mucorales.

Patient's Factors at Entering Hospice Affecting Length of Survival in a Hospice Center.

PURPOSE: In order to provide effective hospice care, adequate length of survival (LOS) in hospice is necessary. However the reported average LOS is much shorter. Analysis of LOS in hospice has not been reported from Korea. We evaluated the duration of LOS and the factors associated with LOS at our hospice center. MATERIALS AND METHODS: We retrospectively examined 446 patients who were admitted to our hospice unit between January 2010 and December 2012. We performed univariate and multivariate analysis for analysis of factors associated with LOS. RESULTS: The median LOS was 9.5 days (range, 1 to 186 days). The LOS of 389 patients (86.8%) was< 1 month. At the time of admission to hospice, 112 patients (25.2%) were completely bedridden, 110 patients (24.8%) had mouth care only without intake, and 134 patients (30.1%) had decreased consciousness, from confusion to coma. The median time interval between the day of the last anticancer treatment and the day of hospice admission was 75 days. By analysis of the results of multivariate analysis, decreased intake and laboratory results showing increased total white blood cell (WBC), decreased platelet count, increased serum creatinine, increased aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) level were poor prognostic factors for survival in hospice. CONCLUSION: Before hospice admission, careful evaluation of the patient's performance, particularly the oral intake, and total WBC, platelet, creatinine, AST, ALT, and LDH level is essential, because these were strong predictors of shorter LOS. In the future, conduct of prospective controlled studies is warranted in order to confirm the relationship between potential prognostic factors and LOS in hospice.

C-reactive protein as a prognostic indicator for rebleeding in patients with nonvariceal upper gastrointestinal bleeding.

BACKGROUND: In patients with acute nonvariceal upper gastrointestinal bleeding, rebleeding after an initial treatment is observed in 10-20% and is associated with mortality. AIM: To investigate whether the initial serum C-reactive protein level could predict the risk of rebleeding in patients with acute nonvariceal upper gastrointestinal bleeding. METHODS: This was a retrospective study using prospectively collected data for upper gastrointestinal bleeding. Initial clinical characteristics, endoscopic features, and C-reactive protein levels were compared between those with and without 30-day rebleeding. RESULTS: A total of 453 patients were included (mean age, 62 years; male, 70.9%). The incidence of 30-day rebleeding was 15.9%. The mean serum C-reactive protein level was significantly higher in these patients than in those without rebleeding (P<0.001). The area under the receiver operating characteristics curve with a cutoff value of 0.5mg/dL was 0.689 (P<0.001). High serum C-reactive protein level (odds ratio, 2.98; confidence interval, 1.65-5.40) was independently associated with the 30-day rebleeding risk after adjustment for the main confounding risk factors, including age, blood pressure, and initial haemoglobin level. CONCLUSIONS: The serum C-reactive protein was an independent risk factor for 30-day rebleeding in patients with acute nonvariceal upper gastrointestinal bleeding, indicating a possible role as a useful screening indicator for predicting the risk of rebleeding.

Aerobic soil metabolism of a new herbicide, LGC-42153.

To elucidate the fate of a new sulfonylurea herbicide, LGC-42153 [N-((4,6-dimethoxypyrimidin-2-yl)aminocarbonyl)-2-(1-methoxyacetoxy-2-fluoropropyl)-3-pyridinesulfonamide], in soil, an aerobic soil metabolism study was carried out for 120 days with [(14)C]LGC-42153 applied to a loamy soil. The material balance ranged from 90.7 to 101.5% of applied herbicide. The half-life of [(14)C]LGC-42153 was calculated to be approximately 9.0 days. The degradation products resulted from the cleavage of the sulfonylurea bridge. The metabolites identified during the study were N-((4,6-dimethoxypyrimidin-2-yl)aminocarbonyl)-2-(1-hydroxy-2-fluoropropyl)-3-pyridinesulfonamide, 2-(1-hydroxy-2-fluoropropyl)-3-pyridinesulfonamide, and 4,6-dimethoxy-2-aminopyrimidine. No significant volatile products or [(14)C]carbon dioxide was observed during the study. Nonextractable (14)C-residue reached 14.4-30.5% of applied material at 120 days after treatment, and radioactivity was distributed mostly in the humin and fulvic acid fractions.

Degradation of the sulfonylurea herbicide LGC-42153 in flooded soil.

LGC-42153, 2-fluoro-1-[3-(4,6-dimethoxypyrimidin-2-ylcarbamoylsulfamoyl)pyridin-2-yl] propyl methoxyacetate, is a new sulfonylurea herbicide for use in rice. Its breakdown and metabolism was studied in soil under flooded conditions using two radioactive tracer compounds labelled at either the propyl group or the pyrimidine ring. The half-life of LGC-42153 was approximately 3.0 days. The mass balance over 120 days ranged from 94.0 to 104.2% of applied radiocarbon, and no significant amount of volatiles or [14C]carbon dioxide were observed. Solvent non-extractable radiocarbon reached about 11-14% of applied radiocarbon at 120 days after treatment. The major metabolic reaction was the cleavage of the carboxyl ester bond to give 1-(4,6-dimethoxypyrimidin-2-yl)-3-[2-(1-hydroxy-2-fluoropropyl)pyridine-3-sulfonyl]urea, which underwent hydrolysis of the sulfonylurea bridge giving 2-(1-hydroxy-2-fluoro)propyl-3-pyridinesulfonamide and 4,6-dimethoxy-2-aminopyrimidine.

Degradation of the sulfonylurea herbicide LGC-42153 in flooded soil.

LGC-42153, 2-fluoro-1-[3-(4,6-dimethoxypyrimidin-2-ylcarbamoylsulfamoyl)pyridin-2-yl]propyl methoxyacetate, is a new sulfonylurea herbicide for use in rice. Its breakdown and metabolism were studied in soil under flooded condition using radioactive tracers labelled at either the propyl group or the pyrimidine ring. The half-life of LGC-42153 was approximately 3.0 days. The mass balance over 120 days ranged from 94.0 to 104.2% of applied radiocarbon, and no significant amount of volatiles or [14C]carbon dioxide were observed. Solvent non-extractable radiocarbon reached 11 approximately 14% of applied radiocarbon at 120 days after treatment. The major metabolic reaction was the cleavage of the carboxyl ester bond to give 1-(4,6-dimethoxypyrimidin-2-yl)-3-[2-(1-hydroxy-2-fluoropropyl)pyridine-3-sulfonyl]urea, which underwent hydrolysis of the sulfonylurea bridge giving 2-(1-hydroxy-2-fluoro)propyl-3-pyridinesulfonamide and 4,6-dimethoxy-2-aminopyrimidine.

Case of inappropriate ADH syndrome: hyponatremia due to polyethylene glycol bowel preparation.

Colonoscopic screening has been reported to reduce deaths from colorectal cancer. Adequate bowel preparation is essential for this and safety is an important issue in choosing the methods. Polyethylene glycol (PEG) is regarded as a safe method for cleansing, especially compared with oral sodium phosphate. Here, we present a case of hyponatremia caused by the syndrome of inappropriate antidiuretic hormone (ADH) syndrome after PEG precolonoscopic cleansing resulting in generalized tonic-clonic seizures. A 62-year-old women had ingested PEG for precolonoscopic bowel cleansing. While waiting for the colonoscopy, she developed a stuporous mentality and generalized tonic-clonic seizures, which did not correlate with brain magnetic resonance imaging. Her serum sodium level was 113 mEq per liter and laboratory analyses were consistent with inappropriate ADH syndrome. Her thyroid and adrenal functions were normal. There were no malignancies, infections, respiratory disorders or central nervous disorders and she had no history of taking either diuretics or other medications, which might have caused inappropriate ADH syndrome. She was treated with 3% hypertonic saline and showed a complete neurological recovery as her sodium levels recovered. Follow-up visits showed the patient to have a normal sodium level without neurologic deficits. This case shows that inappropriate ADH syndrome can be caused by PEG preparation, which implies that physicians have to be aware of the possible side effects of this colonic cleansing approach and mindful of the possible ensuing symptoms.

Undetactable levels of genotoxicity of SiO2 nanoparticles in in vitro and in vivo tests.

BACKGROUND: Silica dioxide (SiO2) has been used in various industrial products, including paints and coatings, plastics, synthetic rubbers, and adhesives. Several studies have investigated the genotoxic effects of SiO2; however, the results remain controversial due to variations in the evaluation methods applied in determining its physicochemical properties. Thus, well characterized chemicals and standardized methods are needed for better assessment of the genotoxicity of nanoparticles. METHODS: The genotoxicity of SiO2 was evaluated using two types of well characterized SiO2, ie, 20 nm (-) charge (SiO (EN20(-))2) and 100 nm (-) charge (SiO (EN100(-))2). Four end point genotoxicity tests, ie, the bacterial mutation assay, in vitro chromosomal aberration test, in vivo comet assay, and in vivo micronucleus test, were conducted following the test guidelines of the Organization for Economic Cooperation and Development (OECD) with application of Good Laboratory Practice. RESULTS: No statistically significant differences were found in the bacterial mutation assay, in vitro chromosomal aberration test, in vivo comet assay, and in vivo micronucleus test when tested for induction of genotoxicity in both two types of SiO2 nanoparticles. CONCLUSION: These results suggest that SiO2 nanoparticles, in particular SiO2 (EN20(-)) and SiO2 (EN100(-)), are not genotoxic in both in vitro and in vivo systems under OECD guidelines. Further, the results were generated in accordance with OECD test guidelines, and Good Laboratory Practice application; it can be accepted as reliable information regarding SiO2-induced genotoxicity.

Recent advances in in vivo genotoxicity testing: prediction of carcinogenic potential using comet and micronucleus assay in animal models.

Genotoxic events have been known as crucial step in the initiation of cancer. To assess the risk of cancer, genotoxicity assays, including comet, micronucleus (MN), chromosomal aberration, bacterial reverse, and sister chromatid exchange assay, can be performed. Compared with in vitro genotoxicity assay, in vivo genotoxicity assay has been used to verify in vitro assay result and definitely provide biological significance for certain organs or cell types. The comet assay can detect DNA strand breaks as markers of genotoxicity. Methods of the in vivo comet assay have been established by Japanese Center for the Validation of Alternative Methods (JaCVAM) validation studies depending on tissue and sample types. The MN can be initiated by segregation error and lagging acentric chromosome fragment. Methods of the in vivo MN assay have been established by Organization for Economic Co-operation and Development (OECD) test guidelines and many studies. Combining the in vivo comet and MN assay has been regarded as useful methodology for evaluating genetic damage, and it has been used in the assessment of potential carcinogenicity by complementarily presenting two distinct endpoints of the in vivo genotoxicity individual test. Few studies have investigated the quantitative relation between in vivo genotoxicity results and carcinogenicity. Extensive studies emphasizes that positive correlation is detectable. This review summarizes the results of the in vivo comet and MN assays that have investigated the genotoxicity of carcinogens as classified by the International Agency for Research on Cancer (IARC) carcinogenicity database. As a result, these genotoxicity data may provide meaningful information for the assessment of potential carcinogenicity and for implementation in the prevention of cancer.