Lower intake of saturated fatty acids is associated with persistently higher arterial stiffness in patients with type 2 diabetes.

AIMS/INTRODUCTION: There are few studies to investigate the relationship between macronutrients and longitudinal changes in arterial stiffness in patients with type 2 diabetes mellitus. This exploratory study sought to determine whether macronutrients were correlated with increased arterial stiffness independently of conventional atherosclerotic risk factors. MATERIALS AND METHODS: The study participants comprised 733 type 2 diabetes outpatients who had no apparent history of cardiovascular diseases. The dietary schedule was assessed with a validated, brief, self-administered diet history questionnaire. At baseline and at years 2 and 5, brachial-ankle pulse wave velocity was measured. A multivariable linear mixed-effects model was used to determine the predictive values of macronutrients and atherosclerotic risk factors for longitudinal changes in brachial-ankle pulse wave velocity. RESULTS: There was a significant increase in brachial-ankle pulse wave velocity values over the 5-year follow-up period. In a multivariable linear mixed-effects model that adjusted for age and sex, lower saturated fatty acid intake was significantly correlated with persistently higher brachial-ankle pulse wave velocity, independently of other atherosclerotic risk factors. Lower intake of dairy products in particular showed this correlation. CONCLUSIONS: Our data showed that lower saturated fatty acids intake was correlated with persistently higher brachial-ankle pulse wave velocity in type 2 diabetes patients. Among food sources of saturated fatty acids, lower dairy products specifically were correlated with elevated brachial-ankle pulse wave velocity. This might be because the consumption of dairy products in Japan is much lower than in Western countries.

Breakfast skipping is associated with persistently increased arterial stiffness in patients with type 2 diabetes.

OBJECTIVE: While certain lifestyle habits may be associated with arterial stiffness, there is limited literature investigating the relationship between lifestyle habits and longitudinal changes in arterial stiffness in patients with type 2 diabetes mellitus (T2DM). This is an exploratory study to determine whether lifestyle habits, in addition to conventional atherosclerotic risk factors, are associated with increased arterial stiffness. RESEARCH DESIGN AND METHODS: The study participants comprised 734 Japanese outpatients with T2DM and no history of apparent cardiovascular diseases. Lifestyle habits were analyzed using self-reported questionnaires, and brachial-ankle pulse wave velocity (baPWV) was measured at baseline, and at years 2 and 5. A multivariable linear mixed-effects model was used to determine the predictive value of lifestyle habits and possible atherosclerotic risk factors for longitudinal change in baPWV. RESULTS: Over 5 years of follow-up, baPWV values significantly increased. In a multivariable linear mixed-effects model that adjusted for age and gender, a low frequency of breakfast intake was significantly associated with persistently high baPWV, independently of other lifestyle habits. Furthermore, in a multivariable linear mixed-effects model that included both lifestyle habits and possible atherosclerotic risk factors, a low frequency of breakfast intake remained the only independent predictive factor for persistently high baPWV. Subjects who ate breakfast less frequently tended to have additional unhealthy lifestyle habits and atherosclerotic risk factors. CONCLUSIONS: Our analyses suggest that breakfast skipping is an independent lifestyle habit that is associated with persistently increased arterial stiffness in patients with T2DM. TRIAL REGISTRATION NUMBER: UMIN000010932.

Relationships Among Conventional Cardiovascular Risk Factors and Lifestyle Habits With Arterial Stiffness in Type 2 Diabetic Patients.

BACKGROUND: While conventional cardiovascular risk factors and certain lifestyle habits are associated with arterial stiffness in patients with type 2 diabetes mellitus (T2DM), it is still unknown whether they are actually associated with arterial stiffness even after adjustment for conventional cardiovascular risk factors and lifestyle habits. The aim of this study was to identify variables that are associated with brachial-ankle pulse wave velocity (baPWV). METHODS: The study participants comprised 724 Japanese T2DM outpatients free of history of cardiovascular diseases. Lifestyle habits were analyzed using self-reported questionnaires. The associations among conventional cardiovascular risk factors and lifestyle habits with baPWV were investigated by multivariable linear regression analysis. RESULTS: The mean age of the study subjects was 57.8 ± 8.6 years, and 62.8% of those were males. The mean HbA1c was 7.0±1.0%, and the estimated duration of T2DM was 9.9 ± 7.2 years. Multiple linear regression analysis that included age and gender demonstrated that age and male sex were positively associated with baPWV. In a model adjusted for numerous conventional cardiovascular risk factors and lifestyle habits, age, duration of T2DM, systolic blood pressure, serum uric acid, urinary albumin excretion and poor sleep quality were positively associated with baPWV, while body mass index was negatively associated with baPWV. CONCLUSIONS: In Japanese T2DM, in addition to several conventional cardiovascular risk factors, poor sleep quality was associated with baPWV even after adjustment for numerous conventional cardiovascular risk factors and lifestyle habits.

Relationships between lifestyle patterns and cardio-renal-metabolic parameters in patients with type 2 diabetes mellitus: A cross-sectional study.

INTRODUCTION: While individuals tend to show accumulation of certain lifestyle patterns, the effect of such patterns in real daily life on cardio-renal-metabolic parameters remains largely unknown. This study aimed to assess clustering of lifestyle patterns and investigate the relationships between such patterns and cardio-renal-metabolic parameters. PARTICIPANTS AND METHODS: The study participants were 726 Japanese type 2 diabetes mellitus (T2DM) outpatients free of history of cardiovascular diseases. The relationship between lifestyle patterns and cardio-renal-metabolic parameters was investigated by linear and logistic regression analyses. RESULTS: Factor analysis identified three lifestyle patterns. Subjects characterized by evening type, poor sleep quality and depressive status (type 1 pattern) had high levels of HbA1c, alanine aminotransferase and albuminuria. Subjects characterized by high consumption of food, alcohol and cigarettes (type 2 pattern) had high levels of γ-glutamyl transpeptidase, triglycerides, HDL-cholesterol, blood pressure, and brachial-ankle pulse wave velocity. Subjects characterized by high physical activity (type 3 pattern) had low uric acid and mild elevation of alanine aminotransferase and aspartate aminotransferase. In multivariate regression analysis adjusted by age, gender and BMI, type 1 pattern was associated with higher HbA1c levels, systolic BP and brachial-ankle pulse wave velocity. Type 2 pattern was associated with higher HDL-cholesterol levels, triglycerides, aspartate aminotransferase, ɤ- glutamyl transpeptidase levels, and diastolic BP. CONCLUSIONS: The study identified three lifestyle patterns that were associated with distinct cardio-metabolic-renal parameters in T2DM patients. TRIAL REGISTRATION: UMIN000010932.

Evaluation of in vivo mutagenicity of isopropyl methanesulfonate by RBC Pig-a and PIGRET assays.

A comparison between the original red blood cell (RBC) Pig-a assay, which measures Pig-a mutant cells in RBCs, and the PIGRET assay, which uses reticulocytes, was conducted using the in vivo mutagenesis assay with isopropyl methanesulfonate (iPMS) as a part of a collaborative study by the Mammalian Mutagenicity Study Group in the Japanese Environmental Mutagen Society. Three dose levels of iPMS (50, 100, and 200mg/kg) were administered once intraperitoneally to 8-week-old male Crl:CD(SD) rats, and peripheral blood was sampled at 0 (1 day before dosing), and 1, 2, and 4 weeks after dosing with iPMS. As a result, a time-dependent increase in the mutant frequency of Pig-a mutant RBCs was observed in the RBC Pig-a assay, and a statistically significant increase was observed from 2 weeks after dosing. In the PIGRET assay, on the other hand, a statistically significant increase in Pig-a mutant frequency was obtained from 1 week after dosing at all dose levels, and the Pig-a mutant frequency at the highest dose level had already reached a plateau on week 1. The maximum Pig-a mutant frequency induced by a single treatment with iPMS at 200mg/kg in the PIGRET assay was approximately two times higher than that in the RBC Pig-a assay. These results indicate that the PIGRET assay can detect Pig-a mutants much earlier and with a higher value in Pig-a mutant frequency compared with the original RBC Pig-a assay, and it can enable judgement of mutagenicity of iPMS within 1 week after a single dose.

PIGRET assay can detect mutagenicity of ethyl methanesulfonate much earlier than RBC Pig-a assay.

The comparison between the original red blood cell (RBC) Pig-a assay, which measures Pig-a mutant RBCs, and the PIGRET assay, which uses reticulocytes, was conducted using in vivo mutagenesis by ethyl methanesulfonate (EMS) as a part of a collaborative study by the Mammalian Mutagenicity Study Group in the Japanese Environmental Mutagen Society. Three dose levels of EMS (180, 360, and 720mg/kg) were administered once by oral gavage to 8-week-old male Crl:CD(SD) rats, and peripheral blood was sampled at 0 (1 day before dosing), 1, 2, and 4 weeks after dosing with EMS. As a result, a statistically significant increase in the mutant frequency of the Pig-a gene was observed from 2 weeks after dosing and a higher value was obtained on week 4 at the highest dose only in the RBC Pig-a assay. In the PIGRET assay, on the other hand, a statistically significant increase in Pig-a mutant frequency was obtained at the highest dose from 1 week after dosing, and it decreased on weeks 2 and 4 compared to the value at week 1. The Pig-a mutant frequency appeared to reach a plateau 1 week after dosing in the PIGRET assay and it might continue to increase even after week 4 in the RBC Pig-a assay. These results indicate that the PIGRET assay can detect Pig-a mutants much earlier than the original RBC Pig-a assay, and it can enable judgement of mutagenicity of EMS within 1 week after a single dosing.

The PIGRET assay, a method for measuring Pig-a gene mutation in reticulocytes, is reliable as a short-term in vivo genotoxicity test: Summary of the MMS/JEMS-collaborative study across 16 laboratories using 24 chemicals.

The in vivo mutation assay using the X-linked phosphatidylinositol glycan class A gene (Pig-a in rodents, PIG-A in humans) is a promising tool for evaluating the mutagenicity of chemicals. Approaches for measuring Pig-a mutant cells have focused on peripheral red blood cells (RBCs) and reticulocytes (RETs) from rodents. The recently developed PIGRET assay is capable of screening >1×106 RETs for Pig-a mutants by concentrating RETs in whole blood prior to flow cytometric analysis. Additionally, due to the characteristics of erythropoiesis, the PIGRET assay can potentially detect increases in Pig-a mutant frequency (MF) sooner after exposure compared with a Pig-a assay targeting total RBCs (RBC Pig-a assay). In order to test the merits and limitations of the PIGRET assay as a short-term genotoxicity test, an interlaboratory trial involving 16 laboratories was organized by the Mammalian Mutagenicity Study Group of the Japanese Environmental Mutagenicity Society (MMS/JEMS). First, the technical proficiency of the laboratories and transferability of the assay were confirmed by performing both the PIGRET and RBC Pig-a assays on rats treated with single doses of N-nitroso-N-ethylurea. Next, the collaborating laboratories used the PIGRET and RBC Pig-a assays to assess the mutagenicity of a total of 24 chemicals in rats, using a single treatment design and mutant analysis at 1, 2, and 4 weeks after the treatment. Thirteen chemicals produced positive responses in the PIGRET assay; three of these chemicals were not detected in the RBC Pig-a assay. Twelve chemicals induced an increase in RET Pig-a MF beginning 1 week after dosing, while only 3 chemicals positive for RBC Pig-a MF produced positive responses 1 week after dosing. Based on these results, we conclude that the PIGRET assay is useful as a short-term test for in vivo mutation using a single-dose protocol.

Relationship between dietary patterns and risk factors for cardiovascular disease in patients with type 2 diabetes mellitus: a cross-sectional study.

BACKGROUND: While some dietary patterns are associated with the incidence of type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD), the relationship between dietary pattern and risk factors for CVD in patients with T2DM remains to be clarified. The aim of this study was to identify dietary patterns and investigate the relationship between dietary patterns and potential risk factors for CVD in patients with T2DM. METHODS: The study participants comprised 726 Japanese T2DM outpatients free of history of CVD. Life styles were analyzed using self-reported questionnaires. The relationship between dietary patterns, identified by factor analysis, and potential risk factors for CVD was investigated by linear and logistic regression analyses. RESULTS: Six dietary patterns were identified by factor analysis. Especially, three dietary patterns were associated with risk factors for CVD. The "Seaweeds, Vegetables, Soy products and Mushrooms" pattern, characterized by high consumption of seaweeds, soy products and mushrooms, was associated with lower use of diabetes medication and healthier lifestyles. The "Noodle and Soup" pattern, characterized by high consumption of noodle and soup was associated with higher body mass index, alanine aminotransferase, aspartate aminotransferase, γ-glutamyl transpeptidase and triglyceride levels. The "Fruit, Dairy products and Sweets" pattern was associated with lower γ-glutamyl transpeptidase levels, blood pressure, albuminuria and brachial-ankle pulse wave velocity. CONCLUSIONS: The findings suggested that dietary patterns correlated with risk factors for CVD in T2DM patients.

Poor sleep quality is associated with increased arterial stiffness in Japanese patients with type 2 diabetes mellitus.

BACKGROUND: While poor sleep quality can worsen cardiovascular risk factors such as glucose and lipid profiles in patients with type 2 diabetes mellitus (T2DM), the relationship between sleep quality and atherosclerosis remains largely unknown. The aim of this study was to examine this relationship. METHODS: The study participants comprised 724 Japanese T2DM outpatients free of history of cardiovascular diseases. The relationships between sleep quality (assessed by the Pittsburgh Sleep Quality Index (PSQI)) and various clinical and laboratory parameters were investigated. RESULTS: The mean PSQI was 5.1 ± 3.0 (±SD). Patients were divided into three groups based on the total PSQI score; subjects with good sleep quality (n = 462), average sleep quality (n = 185), and poor sleep quality (n = 77). In the age/gender-adjusted model, patients with poor sleep quality tended to be obese, evening type and depressed. However, other lifestyles showed no significant trends. Alanine aminotransferase, fasting blood glucose, HbA1c, systolic blood pressure, urinary albumin excretion, and brachial-ankle pulse wave velocity (baPWV) tended to be higher in patients with poor sleep quality. High baPWV was the only parameter that correlated with poor sleep in a model adjusted for several other lifestyle factors. CONCLUSIONS: Our study indicates that poor sleep quality in T2DM patients correlates with increased arterial wall stiffness, a marker of atherosclerosis and a risk factor for cardiovascular diseases.

Morningness-eveningness questionnaire score and metabolic parameters in patients with type 2 diabetes mellitus.

"Morningness" and "Eveningness" represent lifestyle patterns including sleep-wake patterns. Although previous studies described a relationship between the morningness-eveningness trait and glycemic control in patients with type 2 diabetes mellitus (T2DM), the mechanism underlying this association remains unknown. The study participants comprised 725 Japanese T2DM outpatients free of history of cardiovascular diseases. Various lifestyles were analyzed using self-reported questionnaires, including morningness-eveningness questionnaire (MEQ). The relationships between morningness-eveningness trait and various biochemical parameters were investigated by linear regression analysis and logistic regression analysis. We classified the study patients into three groups, morning type (n=117), neither type (n=424) and evening type (n=184). Subjects of the evening type had high levels of alanine aminotransferase, triglyceride, fasting blood glucose and HbA1c and low high-density lipoprotein-cholesterol level in a model adjusted for age and gender. Furthermore, multivariate analysis showed that the evening type was associated with high HbA1c and estimated glomerular filtration rate even after adjustment for other lifestyle factors known to affect metabolic control. The results suggest that T2DM patients with eveningness trait are under inadequate metabolic control independent of other lifestyle factors. Thus, the evening trait of T2DM patients represents an important target for intervention to ensure appropriate metabolic function.

Comparison of effects of pitavastatin and atorvastatin on glucose metabolism in type 2 diabetic patients with hypercholesterolemia.

AIMS/INTRODUCTION: The distinct effects of different statins on glycemic control have not been fully evaluated. In this open-label, prospective, cross-over clinical trial, we compared the effects of pitavastatin and atorvastatin on glycemic control in type 2 diabetic patients with hypercholesterolemia. MATERIALS AND METHODS: A total of 28 Japanese type 2 diabetics with hypercholesterolemia treated with rosuvastatin (2.5 mg/day) for at least 8 weeks were recruited to this quasi-randomized cross-over study. At study entry, the patients assigned to sequence 1 received pitavastatin (2 mg/day) for 12 weeks in period 1 and atorvastatin (10 mg/day) for another 12 weeks in period 2, whereas patients assigned to sequence 2 received atorvastatin (10 mg/day) for 12 weeks in period 1 and pitavastatin (2 mg/day) for another 12 weeks in period 2. Blood samples were collected at three visits (baseline, after 12 and 24 weeks). RESULTS: Lipid control was similar in both statins. The difference in glycated hemoglobin between pitavastatin and atorvastatin treatments was -0.18 (95% confidence interval -0.34 to -0.02; P = 0.03). Compared with atorvastatin, pitavastatin treatment significantly lowered the levels of glycoalbumin, fasting glucose and homeostasis model assessment of insulin resistance. CONCLUSIONS: Our results showed that treatment with pitavastatin had a more favorable outcome on glycemic control in patients with type 2 diabetes compared with atorvastatin. This trial was registered with UMIN (no. 000003554).

Masked hypertension, endothelial dysfunction, and arterial stiffness in type 2 diabetes mellitus: a pilot study.

BACKGROUND: The aim of this study was to assess the relationship between masked hypertension (MHT) and vascular damage in patients with type 2 diabetes. METHODS: The study subjects were patients with type 2 diabetes who were normotensive based on blood pressure (BP) measurement in the clinic (n = 80) without antihypertensive drugs and free of retinopathy, macroalbuminuria, overt cardiovascular disease. Subjects underwent 24-h ambulatory blood pressure monitoring (ABPM), measurement of flow-mediated dilatation (FMD), and brachial-ankle pulse wave velocity (baPWV). Based on the results of ABPM, subjects with mean daytime systolic BP ≥135 and/or 85 mm Hg were defined as MHT and their clinical data were compared with those of normotensive patients (NT). The data were also compared with those of type 2 diabetic patients with hypertension (HT) as measured in the clinic (n = 32). RESULTS: MHT was detected in 47.5% of the study subjects with normotension at clinic (n = 38). Impaired FMD (5.65 ± 2.00% for NT, 4.26 ± 1.88% for MHT, 3.90 ± 1.71% for HT, P < 0.001) and higher baPWV (1,514.2 ± 212.7 cm/s for NT, 1,749.9 ± 339.7 cm/s for MHT, and 1,768.6 ± 302.8 cm/s for HT, P < 0.001) were similarly noted in patients with MHT and HT compared with NT. Multivariate regression analysis indicated that daytime systolic BP measured by ABPM, the estimated duration of diabetes and serum triglycerides were significantly associated with FMD and daytime systolic BP measured by ABPM, not systolic BP at clinic, age, and HbA(1c) were significantly associated with baPWV. CONCLUSIONS: Given that patients with impaired FMD and higher baPWV are known to be at higher risk of cardiovascular disease, our data suggest that type 2 diabetic patients with MHT could be also at increased risk of cardiovascular disease.

Normal islet vascularization is dispensable for expansion of beta-cell mass in response to high-fat diet induced insulin resistance.

The inability to increase of islet mass adequately to compensate for the demand of insulin due to insulin resistance is an important pathophysiological feature of type 2 diabetes. Previous studies suggested a relationship between pancreatic beta-cell mass and islet vascularization, although no evidence has confirmed this association in response to insulin resistance. Vascular endothelial growth factor-A (VEGF-A) in islets is essential for maintaining normal islet blood vessels. Here, insulin resistance was induced in mice carrying a beta-cell-specific VEGF-A gene mutation (RIP-Cre:Vegf(fl/fl)) by 20-week feeding of high-fat diet as a model of impaired islet vascularization. These mice showed only a modest decrease in glucose tolerance, compared with control mice. In addition, although the endothelial cell area in the islets of high-fat-fed RIP-Cre:Vegf(fl/fl) mice remained diminished, the pancreatic beta-cell area was modestly more than in high-fat-fed control mice. Thus, normal islet vascularization does not seem to be essential for expansion of beta cell mass in response to insulin resistance.

Presence of alpha-smooth muscle actin-positive endothelial cells in the luminal surface of adult aorta.

Alpha-smooth muscle actin-positive endothelial cells have not been found in adult aortic endothelium except valve leaflets. Here, using en face immunostaining method, we identified alpha-smooth muscle actin-positive endothelial cells in the luminal surface of rat, mouse and human thoracic aortas. These cells express both endothelial markers and definite smooth muscle cell markers and were only occasionally observed in thoracic aorta of wild type mice and rats. Their density did not increase with aging. Given that alpha-smooth muscle actin-positive endothelial cells express low level of vascular endothelial-cadherin that is important for the maintenance of cell contact, these cells were frequently detected in the thoracic aorta of 5-week-old apolipoprotein-E deficient mice. In 20- to 24-week-old apolipoprotein-E deficient mice, marked accumulation of alpha-smooth muscle actin-positive endothelial cells was observed especially in the luminal surface of atheromatous plaques. Our findings indicate the existence of alpha-smooth muscle actin-positive endothelial cells in adult aortic endothelium and the possible association with progression of atherosclerosis.

Comparison of effects of olmesartan and telmisartan on blood pressure and metabolic parameters in Japanese early-stage type-2 diabetics with hypertension.

Angiotensin II type-1 receptor blockers (ARBs) are regarded as first-line treatments for type-2 diabetes with hypertension. Despite the availability of various types of ARBs, there are no comparative studies of their effects on patients with diabetes. In this open-label prospective crossover study, we compared the effects of olmesartan (20 mg/day) and telmisartan (40 mg/day). Twenty Japanese early-stage type-2 diabetes patients with hypertension treated with valsartan (80 mg/day) for at least 8 weeks were recruited to this study. At study entry, valsartan was changed to olmesartan (20 mg/day) or telmisartan (40 mg/day) and administered for 8 weeks. The drugs were then switched and treatment was continued for another 8 weeks. We analyzed the blood pressure lowering effects of each drug by 24-h ambulatory blood pressure monitoring at 0, 8, and 16 weeks. Simultaneously, we measured metabolic parameters and inflammation markers. Olmesartan lowered mean systolic and diastolic blood pressure more significantly than did telmisartan. While there were no differences between the groups in metabolic parameters, including HbA1c and adiponectin, the decreases in serum interleukin-6 and highly sensitive C-reactive protein were more significant by olmesartan treatment. Our results indicate that olmesartan has more potent arterial blood pressure lowering and anti-inflammatory effects than telmisartan.

Preferable effect of pravastatin compared to atorvastatin on beta cell function in Japanese early-state type 2 diabetes with hypercholesterolemia.

While a large numbers of clinical trials using various kinds of statins has been reported, a possible preventive effect on new onset of type 2 diabetes mellitus was shown only by the subanalysis of The West of Scotland Coronary Prevention Study (WOSCOPS) using pravastatin. The aim of this study was to investigate whether pravastatin has a preferable effect on glucose tolerance among statins. An open-label prospective cross-over trial was performed to compare the effect of pravastatin (10 mg/day) or atorvastatin (10 mg/day) in Japanese early-state type 2 diabetes mellitus with hypercholesterolemia. The analyzed study subjects were treated with pravastatin (10 mg/day, n = 12) or atorvastatin (10 mg/day, n = 12) for 12 weeks. After a 4-week-washout period, the drugs were switched and treatment was continued for another 12 weeks. Oral glucose tolerance test (OGTT) was performed to evaluate several parameters including the appropriateness of beta cell function for the individual insulin sensitivity (disposition index: product of a validated secretion parameter and sensitivity) at the end of each therapy. HbA(1c) and 2 h-glucose levels during OGTT in the pravastatin treatment were significantly lower than atorvastatin treatment. Disposition index after pravastatin treatment was significantly higher than after atorvastatin treatment. In conclusion, our study suggests that pravastatin has a favorable effect on pancreatic beta cell function compared with atorvastatin.

In vitro photochemical clastogenicity of quinolone antibacterial agents studied by a chromosomal aberration test with light irradiation.

The photochemical clastogenic potential of 12 quinolone antibacterial agents with or without light irradiation was assessed by an in vitro chromosomal aberration test using cultured CHL cells. Exposure to all test compounds, except for DK-507k, increased the incidence of cells with structural aberrations excluding gap (TA) following light irradiation. Test compounds used in the present study under light irradiation were divided into three groups based on their ED(50) values, doses inducing chromosomal aberrations in 50% of cells. The first group with ED(50) values below 30 microg/ml includes sparfloxacin (SPFX), clinafloxacin (CLFX), gemifloxacin (GMFX), lomefloxacin (LFLX), sitafloxacin (STFX), grepafloxacin (GPFX) and fleroxacin (FLRX); the second group with ED(50) values of 100 microg/ml, enoxacin (ENX) and levofloxacin (LVFX); the third group with little or no potency, moxifloxacin (MFLX), trovafloxacin (TVFX) and DK-507k. The photochemical clastogenicity of these compounds correlates well with their reported in vivo phototoxic potentials. In the chemical structure and clastogenicity relationships, substitution of a methoxy group at the C-8 position in the quinolone nucleus was confirmed to reduce not only photochemical clastogenicity, but also the clastogenic potential of quinolone antibacterial agents.