Noriyuki Takashi

Effects of Ti ions and particles on neutrophil function and morphology

We compared the cytotoxicity of soluble and particulate titanium (Ti), vanadium (V) and nickel (Ni) by biochemical functional analysis and by microscopic morphology with micro-area elemental analysis in vitro using human neutrophils as probes and in vivo in animals. The biochemical analyses of LDH, superoxide anion, TNF-alpha and scanning electron microscopy (SEM) showed that Ni in solution destroys the cell membrane of neutrophils, whereas Ti and V in solution stimulate neutrophils and increase the quantity of released superoxide anions. Fine Ti particles (1-3 microm), which smaller than neutrophils (about 5 microm), were phagocytized by the cells and the results were similar in vivo. These results showed that the cytotoxic effect of Ti particles is size dependent, and that they must be smaller than that of cells. The present study demonstrated that the biochemical functional tests are useful for evaluating the biocompatibility of materials.

Material nanosizing effect on living organisms: non-specific, biointeractive, physical size effects

Nanosizing effects of materials on biological organisms was investigated by biochemical cell functional tests, cell proliferation and animal implantation testing. The increase in specific surface area causes the enhancement of ionic dissolution and serious toxicity for soluble, stimulative materials. This effect originates solely from materials and enhances the same functions as those in a macroscopic size as a catalyst. There are other effects that become prominent, especially for non-soluble, biocompatible materials such as Ti. Particle size dependence showed the critical size for the transition of behaviour is at approximately 100 μm, 10 μm and 200 nm. This effect has its origin in the biological interaction process between both particles and cells/tissue. Expression of superoxide anions, cytokines tumour necrosis factor-α and interleukin-1β from neutrophils was increased with the decrease in particle size and especially pronounced below 10 μm, inducing phagocytosis to cells and inflammation of tissue, although inductively coupled plasma chemical analysis showed no dissolution from Ti particles. Below 200 nm, stimulus decreases, then particles invade into the internal body through the respiratory or digestive systems and diffuse inside the body. Although macroscopic hydroxyapatite, which exhibits excellent osteoconductivity, is not replaced with natural bone, nanoapatite composites induce both phagocytosis of composites by osteoclasts and new bone formation by osteoblasts when implanted in bone defects. The progress of this bioreaction results in the conversion of functions to bone substitution. Although macroscopic graphite is non-cell adhesive, carbon nanotubes (CNTs) are cell adhesive. The adsorption of proteins and nano-meshwork structure contribute to the excellent cell adhesion and growth on CNTs. Non-actuation of the immune system except for a few innate immunity processes gives the non-specific nature to the particle bioreaction and restricts reaction to the size-sensitive phagocytosis. Materials larger than cell size, approximately 10 μm, behave inertly, but those smaller become biointeractive and induce the intrinsic functions of living organisms. This bioreaction process causes the conversion of functions such as from biocompatibility to stimulus in Ti-abraded particles, from non-bone substitutional to bone substitutional in nanoapatite and from non-cell adhesive to cell adhesive CNTs. The insensitive nature permits nanoparticles that are less than 200 nm to slip through body defence systems and invade directly into the internal body.

Effects of Micro/Nano Particle Size on Cell Function and Morphology

The cytotoxicity of micro/nano particles in Ti, TiO and carbon nanotube was investigated by in vitro biochemical analyses using human neutrophils. The particles smaller and larger than the neutrophils were used to determine the relationship between cell and pa rticle size with respect to cytotoxicity. As the particle size decreased, the cell survival rate was decreased and, with the good corresponding relation to this, the value of lactate dehydrogenase (LDH ), which is the indication of cell disruption, was increased. The release of superoxide anion showed t he increasing tendency. Proinflammatory cytokines were detected distinctly for 3μm or sm aller particles and very little in more than 10μm, which is closely related to the phagocytosis by neutrophil s. ICP elemental analysis showed that the dissolution from Ti particles was below detection li mit. Micro and nano particles stimulated the cell reactions according to the results of the huma n neutrophil functional tests. As the particle size was smaller, the inflammation was pronounced. The fine particl es less than 3μm caused distinctly the inflammation in the surrounding tissue. All these results i ndicated that the cytotoxicity was induced due to the physical size effect of particles, which is different from the ionic dissolution effect. The clinical phenomenon confirmed the result obtained in vitro ce ll tests. The neutrophils stimulated by fine particles may cause the inflammatory cascade and harm the surrounding tissue.

Sjögren's syndrome in the adolescent : report of four cases

We report three cases of Sjögrens syndrome and a case with a probable diagnosis of Sjögrens syndrome at the ages of 16 (2 cases), 17, and 18 years. Two patients were affected by systemic lupus erythematosus. All four patients showed periductal lymphocytic infiltration in the labial glands. Two of the three patients underwent parotid sialography that revealed punctate or globular sialectasis. A decrease in stimulated parotid flow rate was noted in three of the cases compared with age-matched healthy females, whereas only one patient was diagnosed as having keratoconjunctivitis sicca.

Relationship between bite force and body mass index in the institutionalized elderly

Background:  The aim of this study was to evaluate the possible relationship between nutritional status and chewing ability in the institutionalized elderly.

Various Nanotube Scaffolds for Cell Proliferation

Carbon nanotubes (CNT) and their derivatives with different structure and compositions have unique features. In the present study, cell proliferation was performed on various nanotubes such as single walled CNTs, multiwalled CNTs and imogolite which is nanotubes of aluminosilicate. SEM observation of the growth of osteoblast-like cells cultured on CNTs showed the morphology fully developed for the whole direction, which was different from that extended to the one direction on the usual scaffold. Numerous filopodia were grown from cell edge, extended far long and combined with CNT meshwork. Apatite precipitation in simulated body fluid, affinity for proteins and saccharides, and nanosize meshwork structure with large porosity would be the properties responsible for these cell adhesion and growth. Imogolite showed the similar properties to CNTs. Nanotubes could be the favorable materials for biomedical applications.

Visualization of Invasion into the Body and Internal Diffusion of Nanoparticles

Nanoparticles may invade directly into the internal body through the respiratory or digestive system and diffuse inside body. The behavior of nanoparticles in the internal body is also essential to comprehend for the realization of DDS. Thus it is necessary to reveal the internal dynamics for the proper treatments and biomedical applications of nanoparticles. In the present study the plural methods with different principles such as X-ray scanning analytical microscope (XSAM), MRI and Fluorescent microscopy were applied to enable the observation of the internal diffusion of micro/nanoparticles in the (1) whole body level, (2) inner organ level and (3) tissue and intracellular level. Chemical analysis was also done by ICP-AES for organs and compared with the results of XSAM mapping.

Inflammatory Exudates Modulate the Function and Apoptosis of Neutrophils

Abstract Biochemical factors of neutrophils in exudates from acute surgical wounds have been investigated. However, the fate and functions of neutrophils in the exudates have not been clarified and no prior study had compared exudates in the early and late surgical wound stages. The purpose of this study was to investigate the differing effects of exudates on human neutrophils between the early and late phases of inflammation, and to clarify the factors affecting neutrophil function. Exudates from 30 surgical patients with oral cancer who underwent radical neck dissection were collected on the 1st and 5th day after surgery (EX1, EX5). Neutrophils were obtained from two healthy volunteers. Following incubation of the neutrophils with the exudates we examined superoxide anion production and hAPO-1/Fas expression by the neutrophils, apoptosis of the neutrophils and cytokine concentration in the exudates, and the factors related to neutrophil apoptosis. Superoxide anion production by neutrophils incubated with EX1 was significantly higher than by those incubated with EX5, while hAPO-1/Fas expression by the neutrophils was also significantly greater upon incubation with EX5. The DNA ladder was detected only in human neutrophils incubated with EX5. The level of IL-10 in EX1 was significantly lower than that in EX5. Apoptosis of the neutrophils incubated with EX5 was suppressed by the addition of anti-IL-10 antibody. These results indicate that neutrophils have their functions augmented and apoptosis is inhibited in the early phase of inflammation. Furthermore, IL-10 is involved in apoptosis of neutrophils in the late phase of inflammation.