Yatsuji Ito

Chemopreventive Effect of Curcumin on N‐Nitrosomethylbenzylamine‐induced Esophageal Carcinogenesis in Rats

Modifying effects of curcumin (derived from the rhizome of Curcuma longa L.) during the initiation or post‐initiation phase of N‐nitrosomethylbenzylamine (NMBA)‐induced esophageal carcinogenesis were investigated in male F344 rats. Five‐week‐old rats were divided into 5 groups, and groups 1, 2 and 3 were given intraperitoneal injections of NMBA (0.5 mg/kg body weight/injection 15 times) for 5 weeks from 7 weeks old to induce esophageal neoplasms. Groups 2 and 3 were fed the diet containing 500 ppm curcumin during the initiation and post‐initiation phases, respectively. Group 4 was given the diet containing curcumin throughout the experiment, and group 5 was kept on the basal diet alone and served as an untreated control. Incidence and multiplicity of esophageal neoplasms of group 1 (NMBA alone) were 66.7% and 0.83 ±0.70, respectively. Those of groups 2 and 3 were significantly less than those of group 1 (39.3%, 0.46±0.64, P < 0.05; 33.3%, 0.36±0.56, P < 0.05, respectively). Furthermore, the incidence and multiplicity of esophageal preneoplastic lesions (moderate or severe epithelial dysplasia) of group 2 (57.1%, 0.61±0.57; 40%, 0.29±0.46) or 3 (56.7%, 0.67±0.66; 23.3%, 0.23±0.43) were less than those of group 1 (100%, 1.67±0.70; 70.8%, 0.92±0.72) (P < 0.05). In this experiment, feeding of curcumin significantly decreased the expression of cell proliferation biomarkers (5‐bromo‐2′‐deoxyuridine labeling index) in the non‐lesional esophageal epithelium (P < 0.01). These findings indicate that curcumin inhibits NMBA‐induced esophageal carcinogenesis when given during the post initiation as well as initiation phase. This inhibition may be related to suppression of the increased cell proliferation induced by NMBA in the esophageal epithelium.

Activation of caspase-9 and -3 during H2O2-induced apoptosis of PC12 cells independent of ceramide formation.

Abstract The treatment of PCI2 cells with H202 (100-500 µM) resulted in typical apoptotic changes including fragmentation and condensation of nuclei, and DINA fragmentation observed as DNA ladder. H2O2-induced apoptosis was associated with activation of caspase-3 as assessed by cleavage of specific fluorogenic substrate peptide and processing of procaspase-3 and poly(ADP-ribose) polymerase. However, formation of ceramide, which often locates upstream of caspase-3, was not observed. The inhibitory peptide relatively specific for caspase-3, z-DEVD-FMK and non-selective caspase inhibitor z-VAD-FMK inhibited activation of caspase-3 and apoptotic cell death. However, the relatively specific inhibitors, Ac-YVKD for caspase-1 and Ac-IETD for caspase-8/6, did not affect the occurrence of apoptotic cell death. As an upstream activation of caspase-3, induction of cytochrome c release followed by processing of procaspase-9 was observed by Western blotting, although the formation of intracellular ceramide was not observed. On the other hand, in PCI2 cells overexpressing Bcl-2, the number of apoptotic cells was markedly decreased and activation of both caspases-9 and -3 was prevented. These results suggest that cytochrome c and caspase-9 initiate the activation of executor caspase-3 in H2O2-treated PCI2 cells, and that Bcl-2 inhibits H2O2-induced release of cytochrome c from mitochondria and then proteolytic processing of procaspase-9. [Neurol Res 2000; 22: 556-564]

Motion sickness susceptibility associated with visually induced postural instability and cardiac autonomic responses in healthy subjects.

Conclusions This study supports the hypothesis that postural sway and autonomic responses to moving visual stimuli may be associated with motion sickness susceptibility. Characteristics of the cardiac sympathovagal balance during exposure to provocative stimulation may be a marker of individual susceptibility to motion sickness. Objective To assess the relationship between postural and autonomic responses to a simulated visual motion environment and reported susceptibility to motion sickness. Material and methods Fifteen healthy subjects were exposed to sinusoidally oscillating visual motion in roll at frequencies of 0.1–0.4 Hz. Recordings were made of postural sway and respiratory frequency and electrocardiograms were obtained from which heart rate variability (HRV) was computed in order to probe cardiac sympathetic and parasympathetic activity. Results In subjects with a low susceptibility to motion sickness as rated using a standardized questionnaire, there was no significant effect of visual stimulus on postural sway or HRV at any frequency of motion. Subjects with a high susceptibility to motion sickness showed significant postural instability induced by visual stimuli (p<0.01). Visual stimuli presented at a frequency of 0.1 Hz significantly increased the low-frequency power (LF) of HRV, decreased the high-frequency power (HF) of HRV and increased the LF:HF ratio in these subjects (p<0.05).

Dichloroacetate improves immune dysfunction caused by tumor-secreted lactic acid and increases antitumor immunoreactivity.

The activation of oncogenic signaling pathways induces the reprogramming of glucose metabolism in tumor cells and increases lactic acid secretion into the tumor microenvironment. This is a well‐known characteristic of tumor cells, termed the Warburg effect, and is a candidate target for antitumor therapy. Previous reports show that lactic acid secreted by tumor cells is a proinflammatory mediator that activates the IL‐23/IL‐17 pathway, thereby inducing inflammation, angiogenesis and tissue remodeling. Here, we show that lactic acid, or more specifically the acidification it causes, increases arginase I (ARG1) expression in macrophages to inhibit T‐cell proliferation and activation. Accordingly, we hypothesized that counteraction of the immune effects by lactic acid might suppress tumor development. We show that dichloroacetate (DCA), an inhibitor of pyruvate dehydrogenase kinases, targets macrophages to suppress activation of the IL‐23/IL‐17 pathway and the expression of ARG1 by lactic acid. Furthermore, lactic acid‐pretreated macrophages inhibited CD8+ T‐cell proliferation, but CD8+ T‐cell proliferation was restored when macrophages were pretreated with lactic acid and DCA. DCA treatment decreased ARG1 expression in tumor‐infiltrating immune cells and increased the number of IFN‐γ‐producing CD8+ T cells and NK cells in tumor‐bearing mouse spleen. Although DCA treatment alone did not suppress tumor growth, it increased antitumor immunotherapeutic activity of Poly(IC) in both CD8+ T cell‐ and NK cell‐sensitive tumor models. Therefore, DCA acts not only on tumor cells to suppress glycolysis but also on immune cells to improve the immune status modulated by lactic acid and to increase the effectiveness of antitumor immunotherapy.

Ultrastructural alterations induced by Amphotericin B in the plasma membrane of Epidermophyton floccossum as revealed by freeze-etch electron microscopy

Abstract Freeze-etch electron microscopic observations demonstrated that Amphotericin B, a potential antifungal polyene induced profound ultrastructural alterations in the plasma membrane of cells of a human pathogenic fungus, Epidermophyton floccosum ; aggregation of membrane-associated particles (85-A) and formation of depressions (or craters) on the inner fracture face. Thin-sectioning electron microscopy showed “vesiculation” of plasma membranes of Amphotericin B-treated Epidemophyton cells. It can be suggested from the preliminary results that the fungal cells which contain ergosterol as the major sterol are highly sensitive to Amphotericin B.

The functional effectiveness of neck muscle reflexes for head-righting in response to sudden fall

Abstract Reflex head-righting in normal and labyrinthine-defective (LD) subjects was compared to identify the relative functional effectiveness of vestibular-collic and cervico-collic myotactic reflexes. To restrict stimuli largely to the head and neck, subjects lay supine, supported up to the shoulders on a horizontal bed with their head supported in a sling over the edge. The head fell freely as the sling was released with an electromagnetic catch. Head drops were delivered with the subjects instructed to relax and accept the fall passively or to actively right the head as fast as possible. With both instructions, righting responses in normal subjects commenced with electromyographic (EMG) bursts in the sternocleidomastoid (SCM) at 24.5 ms latency, which was reflected in a deceleration of the downwards head velocity. The latency of the earliest EMG responses in LD subjects was 67.4 ms, accompanied by similar deceleration. It is assumed that the earliest response in normal subjects is vestibular, whereas in LDs the SCM stretch reflex is the earliest response. These reflexes are followed at circa 100 ms by more intense EMG activity due to voluntary movement, but braking of head fall is evident before voluntary activity takes effect. Righting was more effective in normal subjects than in LDs, and when “active” normal subjects made more vigorous righting responses than when “passive”; whereas active righting in LDs was no better than passive. The results demonstrate that reflex responses contribute significantly to head-righting. The vestibular contribution gives an advantage over stretch reflexes alone and also assists in voluntary enhancement of reflex responses.

Surface structure of dermatophytes as seen by the scanning electron microscope

Several selected strains of dermatophytes, Microsporum cookei HUT-2061, Epidermophyton floccosum TEF-30, and Trichophyton species (T. tonsurans A410, T. fluviomuniense 3635, T. megnini 4034 and T. rubrum T-1005) were examined using a scanning electron microscope. The characteristic features of the dermatophytes suggest a possibility of application of this technique to classification of pathogenic fungi.

The association of antidiuretic hormone levels with an attack of Meniere's disease

Objectives:  An elevation of the plasma antidiuretic hormone (ADH) levels has frequently been observed in Menieres disease patients. However, little is known regarding the mechanism behind such an elevation of ADH level in Menieres disease patients. Therefore, we measured the plasma ADH in Menieres disease patients and other vertigo patients to elucidate the association between the ADH levels, stress levels and the development of Menieres symptom.

Subclinical deviation of the subjective visual vertical in patients affected by a primary headache

Conclusion. Our results suggest that patients with migraine or tension-type headache have subclinical deviations of the subjective visual vertical, which may be associated with their subjective imbalance Objectives. Patients affected by migraine or tension-type headache often complain of unsteadiness. However, they rarely show a clinical significance in the objective examinations of their equilibrium. We investigated the equilibrium functions in patients affected by migraine or tension-type headache Subjects and methods. We investigated the neurotological findings of 17 patients with migraine, 20 patients with tension-type headaches, and 16 patients without headache. All patients in this study experienced vertigo or dizziness before they underwent the examination; however, they never had vertigo attacks for more than 1 month before the examination. All patients in this study were tested during headache-free intervals Results. There was no significant difference in the hearing levels of pure tone audiometry, the canal palsy percentage of bithermal caloric test, and the body sway in posturography among the three groups (p>0.05, Mann-Whitney U test). The average values in absolute deviations of subjective visual vertical (SVV) in patients with tension-type headache (1.3±1.1°) and patients with migraine (1.5±1.2°) were significantly larger in comparison with those of patients without headache (0.6±0.4) (p<0.05, Mann-Whitney U test). Intra-individual varaiances of the SVV in patients with primary headache were significantly larger than those in patients without headache (p<0.05, Mann-Whitney U test).

Increased expression of phospholipase D1 mRNA during cAMP- or NGF- induced differentiation in PC12 cells

The rat pheochromocytoma PC12 cells have been employed as a useful model to study neuronal differentiation. To gain insight into the molecular events involved in extension of neurites, the differential expression of phospholipase D (PLD) isozymes were examined in cyclic AMP- or nerve growth factor (NGF)-treated PC12 cells. When the cells were incubated with dibutyryl cyclic AMP (dbcAMP), almost all the cells displayed prominent neurite outgrowth at 24 h. The neurites developed in NGF-treated cells at 24 h were shorter than those in the cells treated with dbcAMP. However, most of the NGF-treated cells extended long neurites at day 5. The rPLD1b mRNA increased within 6 h following dbcAMP treatment and maintained a high level up to 24 h. In contrast, the levels of rPLD1a and rPLD2 mRNAs were rather consistent throughout the time course examined. However, when the cells were treated with NGF, rPLD1a and rPLD1b mRNAs, but not rPLD2 mRNA, increased within 2 days and remained elevated up to 5 days. These results suggest the possible implication of PLD1 in PC12 cell differentiation.