Multiwalled carbon nanotubes (MWCNTs) have the potential for widespread applications in engineering and materials science. However, because of their needle-like shape and high durability, concerns have been raised that MWCNTs may induce asbestos-like pathogenicity. Although recent studies have demonstrated that MWCNTs induce various types of reactivities, the physicochemical features of MWCNTs that determine their cytotoxicity and carcinogenicity in mesothelial cells remain unclear. Here, we showed that the deleterious effects of nonfunctionalized MWCNTs on human mesothelial cells were associated with their diameterdependent piercing of the cell membrane. Thin MWCNTs (diameter ∼ 50 nm) with high crystallinity showed mesothelial cell membrane piercing and cytotoxicity in vitro and subsequent inflammogenicity and mesotheliomagenicity in vivo. In contrast, thick (diameter ∼ 150 nm) or tangled (diameter ∼ 2-20 nm) MWCNTs were less toxic, inflammogenic, and carcinogenic. Thin and thick MWCNTs similarly affected macrophages. Mesotheliomas induced by MWCNTs shared homozygous deletion of Cdkn2a/2b tumor suppressor genes, similar to mesotheliomas induced by asbestos. Thus, we propose that different degrees of direct mesothelial injury by thin and thick MWCNTs are responsible for the extent of inflammogenicity and carcinogenicity. This work suggests that control of the diameter of MWCNTs could reduce the potential hazard to human health. environmental health | inflammation | nanotoxicology

Asbestos is a potent carcinogen associated with increased risks of malignant mesothelioma and lung cancer in humans. Although the mechanism of carcinogenesis remains elusive, the physicochemical characteristics of asbestos play a role in the progression of asbestos-induced diseases. Among these characteristics, a high capacity to adsorb and accommodate biomolecules on its abundant surface area has been linked to cellular and genetic toxicity. Several previous studies identified asbestos-interacting proteins. Here, with the use of matrix-assisted laser desorption ionization-time of flight mass spectrometry, we systematically identified proteins from various lysates that adsorbed to the surface of commercially used asbestos and classified them into the following groups: chromatin ⁄ nucleotide ⁄ RNA-binding proteins, ribosomal proteins, cytoprotective proteins, cytoskeleton-associated proteins, histones and hemoglobin. The surfaces of crocidolite and amosite, two iron-rich types of asbestos, caused more protein scissions and oxidative modifications than that of chrysotile by in situ-generated 4-hydroxy-2-nonenal. In contrast, we confirmed the intense hemolytic activity of chrysotile and found that hemoglobin attached to chrysotile, but not silica, can work as a catalyst to induce oxidative DNA damage. This process generates 8-hydroxy-2¢-deoxyguanosine and thus corroborates the involvement of iron in the carcinogenicity of chrysotile. This evidence demonstrates that all three types of asbestos adsorb DNA and specific proteins, providing a niche for oxidative modification via catalytic iron. Therefore, considering the affinity of asbestos for histones ⁄ DNA and the internalization of asbestos into mesothelial cells, our results suggest a novel hypothetical mechanism causing genetic alterations during asbestos-induced carcinogenesis. (Cancer Sci 2011; 102: 2118-2125 A sbestos is a natural fibrous mineral that was heavily used in industry during the past century because of its durability, heat resistance and low cost. However, it has become clear that respiratory exposure to asbestos fibers, especially crocidolite and amosite, which have high biopersistence and contain abundant iron, is associated with high risks of developing malignant mesothelioma and lung cancer.(1-3) Many countries anticipate increased numbers of mesothelioma patients in the coming decades because there is an extremely long incubation period (30-40 years) for this fatal disease following asbestos exposure. (4) The molecular mechanism of asbestos-induced carcinogenesis remains elusive, (5) but both mesothelial cell injury and persistent macrophage activation are thought to be essential, if not sufficient, for mesotheliomagenesis.(6) These two events interact in vivo, leading to genetic mutations, chromosomal aberrations and aneuploidy in mesothelial cells. At least four major hypotheses related to the underlying mechanisms have been proposed. (6,7) First, the free radical theory postulates that DNA is injured by reactive oxygen species generated th...

Heart failure (HF) is a progressive systemic disease and a major public health problem in developed countries [1]. Despite modern progress in medical management, HF remains a common cause of recurrent hospitalization or death, and a number of prognostic predictors of HF have been reported, including age, New York Heart Association (NYHA) functional class, HF admission, clinical history of hypertension or chronic obstructive pulmonary disease, etiology of cardiomyopathy, blood pressure, brain natriuretic peptide (BNP) level, and parameters of echocardiography or electrocardiogram [2,3]. On the other hand, HF is a systemic clinical syndrome with multiple impaired organs due to low perfusion and congestion

AimsIn acute heart failure (AHF), immobilization is caused because of unstable haemodynamics and dyspnoea, leading to protein wasting. Neuromuscular electrical stimulation (NMES) has been reported to preserve muscle mass and improve functional outcomes in chronic disease. NMES may be effective against protein wasting frequently manifested in patients with AHF; however, whether NMES can be implemented safely without any adverse effect on haemodynamics has remained unknown. This study aimed to examine the feasibility of NMES in patients with AHF.Methods and resultsPatients with AHF were randomly assigned to the NMES or control group. The intensity of the NMES group was set at 10–20% maximal voluntary contraction level, whereas the control group was limited at a visible or palpable level of muscle contraction. The sessions were performed 5 days per week since the day after admission. Before the study implementation, we set the feasibility criteria with following items: (i) change in systolic blood pressure (BP) > ±20 mmHg during the first session; (ii) increase in heart rate (HR) > +20 b.p.m. during the first session; (iii) development of sustained ventricular arrhythmia, atrial fibrillation (AF), and paroxysmal supraventricular tachycardia during all sessions; (iv) incidence of new‐onset AF during the hospitalization period < 40%; and (v) completion of the planned sessions by >70% of patients. The criteria of feasibility were set as follows; the percentage to fill one of (i)–(iii) was <20% of the total subjects, and both (iv) and (v) were satisfied. A total of 73 patients (median age 72 years, 51 men) who completed the first session were analysed (NMES group, n = 34; control group, n = 39). Systolic BP and HR variations were not significantly different between two groups (systolic BP, P = 0.958; HR, P = 0.665). Changes in BP > ±20 mmHg or HR > +20 b.p.m. were observed in three cases in the NMES group (8.8%) and five in the control group (12.8%). New‐onset arrhythmia was not observed during all sessions in both groups. During hospitalization, one patient newly developed AF in the NMES group (2.9%), and one developed AF (2.6%) and two lethal ventricular arrhythmia in the control group. Thirty‐one patients in the NMES group (91%) and 33 patients in the control group (84%) completed the planned sessions during hospitalization. This study fulfilled the preset feasibility criteria.ConclusionsNMES is feasible in patients with AHF from immediately after admission.

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