Tetsuya Adachi

Bio: Tetsuya Adachi is an academic researcher from Kyoto Prefectural University of Medicine. The author has contributed to research in topics: Eosinophil & Bone tissue. The author has an hindex of 16, co-authored 70 publications receiving 811 citations.

Eosinophil apoptosis caused by theophylline, glucocorticoids, and macrolides after stimulation with IL-5

Abstract: BACKGROUND: Glucocorticoids have long been used as the most potent drugs in the treatment of bronchial asthma. Data reported recently have led to the proposal that theophylline and macrolides have antiinflammatory effects. OBJECTIVE: We examined the abilities of theophylline, glucocorticoids, and macrolides to counteract the prolongation of eosinophil survival caused by IL-5. METHODS: Purified guinea pig eosinophils were cultured in the presence or absence of human IL-5 and with or without the aforementioned drugs at various concentrations. The percentage of cells alive after 3 days in culture was determined. RESULTS: Aminophylline (AM), methylprednisolone (MP), erythromycin (EM), and clarithromycin (CAM) suppressed the IL-5 induced prolongation of eosinophil survival in a dose-dependent manner. The effects of these drugs on eosinophil survival were significantly greater at low concentrations of IL-5 than at high concentrations of IL-5. When eosinophils were cultured in the presence of IL-5 (1 ng/ml) with physiologic concentrations of MP (10 -6 mol/L), AM (10 -4 mol/L), and either EM or CAM (both 10 μg/ml), the effect of IL-5 was almost completely abolished, and the morphologic changes in eosinophils observed by electron microscopy were consistent with apoptosis. DNA extracted from eosinophils cultured with IL-5 and each of the drugs was definitely fragmented. CONCLUSIONS: One mechanism of the effectiveness of these drugs is induction of eosinophil apoptosis. Some combination of these drugs may be useful in the treatment of bronchial asthma. (J ALLERGY CLIN IMMUNOL 1996;98:207-15.)

Bioactive silicon nitride: A new therapeutic material for osteoarthropathy.

Abstract: While the reciprocity between bioceramics and living cells is complex, it is principally governed by the implant’s surface chemistry. Consequently, a deeper understanding of the chemical interactions of bioceramics with living tissue could ultimately lead to new therapeutic strategies. However, the physical and chemical principles that govern these interactions remain unclear. The intricacies of this biological synergy are explored within this paper by examining the peculiar surface chemistry of a relatively new bioceramic, silicon nitride (Si3N4). Building upon prior research, this paper aims at obtaining new insights into the biological interactions between Si3N4 and living cells, as a consequence of the off-stoichiometric chemical nature of its surface at the nanometer scale. We show here yet unveiled details of surface chemistry and, based on these new data, formulate a model on how, ultimately, Si3N4 influences cellular signal transduction functions and differentiation mechanisms. In other words, we interpret its reciprocity with living cells in chemical terms. These new findings suggest that Si3N4 might provide unique new medicinal therapies and effective remedies for various bone or joint maladies and diseases.

Silicon Nitride Bioceramics Induce Chemically Driven Lysis in Porphyromonas gingivalis

Abstract: Organisms of Gram-negative phylum bacteroidetes, Porphyromonas gingivalis, underwent lysis on polished surfaces of silicon nitride (Si3N4) bioceramics. The antibacterial activity of Si3N4 was mainly the result of chemically driven principles. The lytic activity, although not osmotic in nature, was related to the peculiar pH-dependent surface chemistry of Si3N4. A buffering effect via the formation of ammonium ions (NH4(+)) (and their modifications) was experimentally observed by pH microscopy. Lysis was confirmed by conventional fluorescence spectroscopy, and the bacteria's metabolism was traced with the aid of in situ Raman microprobe spectroscopy. This latter technique revealed the formation of peroxynitrite within the bacterium itself. Degradation of the bacteria's nucleic acid, drastic reduction in phenilalanine, and reduction of lipid concentration were observed due to short-term exposure (6 days) to Si3N4. Altering the surface chemistry of Si3N4 by either chemical etching or thermal oxidation influenced peroxynitrite formation and affected bacteria metabolism in different ways. Exploiting the peculiar surface chemistry of Si3N4 bioceramics could be helpful in counteracting Porphyromonas gingivalis in an alkaline pH environment.

Incorporating Si3N4 into PEEK to Produce Antibacterial, Osteocondutive, and Radiolucent Spinal Implants

Abstract: Polyetheretherketone (PEEK) is a popular polymeric biomaterial which is primarily used as an intervertebral spacer in spinal fusion surgery; but it is developed for trauma, prosthodontics, maxillofacial, and cranial implants. It has the purported advantages of an elastic modulus which is similar to native bone and it can be easily formed into custom 3D shapes. Nevertheless, PEEK's disadvantages include its poor antibacterial resistance, lack of bioactivity, and radiographic transparency. This study presents a simple approach to correcting these three shortcomings while preserving the base polymer's biocompatibility, chemical stability, and elastic modulus. The proposed strategy consists of preparing a PEEK composite by dispersing a minor fraction (i.e., 15 vol%) of a silicon nitride (Si3 N4 ) powder within its matrix. In vitro tests of PEEK composites with three Si3 N4 variants-β-Si3 N4 , α-Si3 N4 , and β-SiYAlON-demonstrate significant improvements in the polymer's osteoconductive versus SaOS-2 cells and bacteriostatic properties versus gram-positive Staphylococcus epidermidis bacteria. These properties are clearly a consequence of adding the bioceramic dispersoids, according to chemistry similar to that previously demonstrated for bulk Si3 N4 ceramics in terms of osteogenic behavior (vs both osteosarcoma and mesenchymal progenitor cells) and antibacterial properties (vs both gram-positive and gram-negative bacteria).

Silicon Nitride: A Synthetic Mineral for Vertebrate Biology.

Abstract: The remarkable stoichiometric flexibility of hydroxyapatite (HAp) enables the formation of a variety of charged structural sites at the material's surface which facilitates bone remodeling due to binding of biomolecule moieties in zwitterionic fashion. In this paper, we report for the first time that an optimized biomedical grade silicon nitride (Si3N4) demonstrated cell adhesion and improved osteoconductivity comparable to highly defective, non-stoichiometric natural hydroxyapatite. Si3N4's zwitterionic-like behavior is a function of the dualism between positive and negative charged off-stoichiometric sites (i.e., N-vacancies versus silanols groups, respectively). Lattice defects at the biomaterial's surface greatly promote interaction with positively- and negatively-charged functional groups in biomolecules, and result in the biologically effective characteristics of silicon nitride. These findings are anticipated to be a starting point for further discoveries of therapeutic bone-graft substitute materials.

Asthma. From bronchoconstriction to airways inflammation and remodeling.

Abstract: Introduction Acute Inflammation and Brief Symptoms Mechanisms: Experimentally Induced Allergic Reactions Clinical Consequences and Treatment Chronic Inflammation Site of the Inflammation in Asthma Cell Survival in Airway Tissues Characteristics of Chronic Inflammation Chronic Inflammation in the Different Forms of Asthma Clinic Consequences Treatment of Exacerbations Onset and Duration of Treatment Remodeling of the Airways Characteristics of Airways Remodeling in Asthma Clinical Consequences Radiographic Findings Treatment and Prevention of Airways Remodeling Conclusions

Direct writing by way of melt electrospinning

Abstract: Melt electrospun fibers of poly(ϵ-caprolactone) are accurately deposited using an automated stage as the collector. Matching the translation speed of the collector to the speed of the melt electrospinning jet establishes control over the location of fiber deposition. In this sense, melt electrospinning writing can be seen to bridge the gap between solution electrospinning and direct writing additive manufacturing processes.

An overview: biomolecules from microalgae for animal feed and aquaculture

Abstract: Despite being more popular for biofuel, microalgae have gained a lot of attention as a source of biomolecules and biomass for feed purposes. Algae farming can be established using land as well as sea and strategies can be designed in order to gain the products of specific interest in the optimal way. A general overview of the contributions of Algae to meet the requirements of nutrients in animal/aquaculture feed is presented in this study. In addition to its applications in animal/aquaculture feed, algae can produce a number of biomolecules including astaxanthin, lutein, beta-carotene, chlorophyll, phycobiliprotein, Polyunsaturated Fatty Acids (PUFAs), beta-1,3-glucan, and pharmaceutical and nutraceutical compounds which have been reviewed with respect to their commercial importance and current status. The review is further extended to highlight the adequate utilization of value added products in the feeds for livestock, poultry and aquaculture (with emphasis in shrimp farming).