Biomedical subjects

T Oi

Publications and source records attributed to T Oi.

At least 19 recordsLinked to original sources

PubMed2000

A new nitroxyl-probe with high retention in the brain and its application for brain imaging.

In order to estimate free radical reactions and image them in the brain of living animals, a nitroxyl spin-probe, carboxy-PROXYL acetoxymethyl ester (CxP-AM) was newly synthesized. CxP-AM was designed to be hydrolyzed by esterase, but not by lipase, so that it would pass through the blood-brain barrier and be retained in the cytosolic phase of parenchymal cells in the brain after intravenous injection. The pharmacokinetics of CxP-AM was compared with those of carboxy-PROXYL (CxP) and its methyl ester (CxP-M). Carboxyl esterase almost completely hydrolyzed CxP-AM within 3 min. After intravenous injection, the brain retained 1.8 times more CxP-AM than CxP-M, and retained it for more than 30 min. Electron spin resonance computed tomographic (ESR-CT) imaging of CxP-AM in the heads of mice produced marked contrast in the encephalon region, while CxP was distributed only in the extracranial region and CxP-M was distributed in both regions, confirming the pharmacokinetics of CxP-AM. The decay rate of CxP-AM determined with time-resolved ESR-CT imaging was different in the two brain regions, suggesting regional differences in the total reducing capability. CxP-AM should become a powerful probe for the investigation and diagnosis of free radical reactions and their imaging in the brain.

Animals↗

PubMed1999

New sensitive agents for detecting singlet oxygen by electron spin resonance spectroscopy.

Free radicals are well-established transient intermediates in chemical and biological processes. Singlet oxygen, though not a free radical, is also a fairly common reactive chemical species. It is rare that singlet oxygen is studied with the electron spin resonance (ESR) technique in biological systems, because there are few suitable detecting agents. We have recently researched some semiquinone radicals. Specifically, our focus has been on bipyrazole derivatives, which slowly convert to semiquinone radicals in DMSO solution in the presence of potassium tert-butoxide and oxygen. These bipyrazole derivatives are dimers of 3-methyl-1-phenyl-2-pyrazolin-5-one and have anti-ischemic activities and free radical scavenging properties. In this work, we synthesized a new bipyrazole derivative, 4,4'-bis(1p-carboxyphenyl-3-methyl-5-hydroxyl)-pyrazole, DRD156. The resulting semiquinone radical, formed by reaction with singlet oxygen, was characterized by ESR spectroscopy. DRD156 gave no ESR signals from hydroxyl radical, superoxide, and hydrogen peroxide. DRD156, though, gives an ESR response with hypochlorite. This agent, nevertheless, has a much higher ability to detect singlet oxygen than traditional agents with the ESR technique.

Dimethyl Sulfoxide↗

PubMed1995

Effects of FMLP and LPS on [Ca2+]i of peritoneal exudate polymorphonuclear leukocytes following onset of inflammation.

Because a general study of activated neutrophils may have relevance to periodontal diseases and accompanying inflammation, we studied a function of mouse polymorphonuclear leukocytes (PMNs) that exude into the peritoneal cavity in response to inflammation caused by i.p. injection of 2% casein. The effects of E. coli-lipopolysaccharide (E-LPS) and a chemotactic factor, N-formyl-N-methionyl-N-leucyl-L-phenylalanine (FMLP), on the level of intracellular calcium ([Ca2+]i) in these PMNs were examined. From analysis made with a laser cytometer (ACAS 570), the PMNs in exudates harvested 3-9 h after the onset of inflammation were shown to undergo [Ca2+]i elevation in response to 10(-6) M FMLP. The peak concentration of [Ca2+]i elicited by FMLP was highest in exudate cells 6 h after casein injection. In addition, about 65% of the PMNs in the 3-h exudate were FMLP sensitive displaying an elevated [Ca2+]i, whereas more than 85% of them in 6- and 9-h exudates became FMLP sensitive. Also, the maximum level of [Ca2+]i after FMLP stimulation was potentiated by pretreatment of the cells with E-LPS (0.2 microgram/ml). The present study suggests that PMNs induced by casein injection and appearing in mouse peritoneal exudate at different times possess significantly different ability to undergo [Ca2+]i elevation, and different susceptibility toward a chemotactic factor, FMLP.

Animals↗

PubMed1990

[Report on clinico-pathological examinations in Meikai University (formerly Josai Dental University) Hospital (4)].

This clinico-pathological study was conducted to examine biopsies and surgical specimens for histopathological diagnosis from April 1983 to March 1988 in Meikai University (formerly Josai Dental University) Hospital. The following statistical results were obtained: 1) The total number of the specimens examined was 2705, 2026 from the dental clinic and 679 from the medical clinic. 2) Concerning age distribution, most specimens from the dental clinic were from patients in the 40's age bracket, whereas most from the medical clinic were from those under 10 years of age. With regard to sex distribution, the difference between males and females was not so much in the dental clinic specimens, but the number from the medical clinic was greater for males than for females. 3) Concerning classification of the tumors from the dental clinic, 181 cases were benign; and of them 41 were odontogenic and 140 were non-odontogenic tumors. Among the odontogenic tumors, ameloblastoma, cementoma, and odontoma were the most numerous. Among non-odontogenic tumors, fibroma was the most common, followed by pleomorphic adenoma. Malignant tumors comprised 77 cases. Of them squamous cell carcinoma was the most commonly found, with the grade-2 type being most numerous. Of the medical clinic tumors, nevus was the most common benign tumor observed; and adenocarcinoma, the most common malignant one. 4) Concerning the distribution of main lesions in the dental clinic specimens, most specimens were cysts or cystic lesions, followed by inflammatory lesions and tumors. Among medical clinic specimens, inflammatory lesions were the most common. 5) Regarding the dental clinic specimens, the most frequently observed case was the radicular cyst (301 samples) among the odontogenic cysts (514 samples); and among non-odontogenic cysts (290 samples), the most common was the mucous cyst (159 samples). 5) In terms of the distribution by location, tissue or organ, most tumors from the dental clinic were from the jaws, followed in descending frequency by those from gingiva and alveolar mucosa, maxillary sinus, lip, buccal mucosa, and tongue. Among the medical clinic tumors, the paranasal cavity and tonsils were the most frequent locations.

Adult↗

PubMed1986