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Biomedical subjects

I Nashimoto

Publications and source records attributed to I Nashimoto.

14 recordsLinked to original sources
PubMed1992

Near-infrared imaging in vivo (I): Image restoration technique applicable to the NIR projection images.

To enhance spatial resolution of NIR projection images in vivo, we performed refocusing of NIR projection images of human forearm of about 50 mm thickness. A volunteer's forearm was illuminated by parallel light beam-flux, and then projection images at 750 nm was measured with a Pertier-cooled CCD video camera and digitized. For refocusing computation, PSF of the light transmitted through the tissue was calculated by general equation proposed by van der Zee and Delpy (1988). Simple inverse, constrained least squares, and Wiener filters were tested as refocusing algorithms. Wiener filter gave the best result in terms of image quality and computation time. By applying Wiener filter to the image refocusing of NIR projection images of human forearm, we obtained enhanced spatial resolution.

Evaluation Studies as Topic↗
PubMed1992

Near-infrared imaging in vivo (II): 2-Dimensional visualization of tissue oxygenation state.

By measuring NIR projection images at 700 and 800 nm, we examined 2-dimensional visualization of Hb oxygenation state in the human forearm of about 50 mm thickness. Equations for selective quantification of oxy-Hb, deoxy-Hb, and SO2 were derived from in vitro experiment, and validity of the equations were checked by using a test phantom which simulates optical properties of living tissues. Forearm occlusion caused increase in 2-dimensional O.D. image at 700 nm, while slight decrease was observed in the image at 800 nm. These results were consistent with changes in NIR spectra caused by the forearm occlusion and explained by Hb deoxygenation and slight decrease in blood volume. Although several uncertain errors seemed to remain in our results, we obtained an essentially reasonable image which demonstrates 2-dimensional changes in Hb oxygenation in the human forearm caused by forearm ischemia.

Evaluation Studies as Topic↗
PubMed1989

Ovarian Sertoli-Leydig cell tumor with elevated serum alpha-fetoprotein.

An 18-year-old girl with virilization and an elevated level of serum alpha-fetoprotein (AFP) was found to have a Sertoli-Leydig cell tumor (SLCT) of the ovary. The tumor had a heterologous element of gastrointestinal type epithelium, retiform pattern, and multilocular cysts, many of which were lined by Sertoli-like cells. Alpha-fetoprotein was detected immunohistochemically in cells with the histologic appearance of Sertoli cells, and testosterone was detected in the Leydig cells. Results of lectin affinity chromatography indicated that AFP produced by this tumor was different from the AFP to be found in the liver.

Adolescent↗
PubMed1989

Multicomponent analysis of near-infrared spectra of anesthetized rat head: (I). Estimation of component spectra by principal component analysis.

By measuring precise NIR spectra of anesthetized rat head, we determined principal components included in changes of the NIR spectra caused by acute hypoxia. There was apparent delay in reduction of cyt. aa3 as compared with Hb deoxygenation in the hypoxic period. With regard to the eigenvalues determined by principal component analysis, principal components in the NIR spectral changes caused by acute hypoxia were Hb and cyt. aa3, and contribution of the remaining biological materials to the changes in NIR spectra caused by acute hypoxia was considered to be negligible in quantitative multivariate analysis of Hb and cyt. aa3 in situ.

Animals↗
PubMed1989

Multicomponent analysis of near-infrared spectra of anesthetized rat head: (II). Quantitative multivariate analysis of hemoglobin and cytochrome oxidase by non-negative least squares method.

We developed a method for quantitating absolute value of Hb oxygenation and that of redox state of cyt. aa3 on the basis of multiple regression analysis of near-infrared spectrophotometric data. Flattening of the spectrum of Hb in both RBC suspension and the brain in situ was observed. This phenomenon was explained by localization of Hb within RBC for in vitro flattening, and by localization of RBC within the vessels as well as deformation of RBC in the microcirculation in vivo. Under resting air-breathing conditions, So2 and redox state of cyt. aa3 were estimated to be 50-70% and over 90%, respectively. Increase in FIO2 up to 3 ATA O2 caused stepwise increase in So2, whereas cyt. aa3 was fully oxidized when the animal inspired O2 under 1 ATA. Problems which must be solved for more accurate estimation of absolute values of So2 and redox state of cyt. aa3 were described and discussed.

Algorithms↗
PubMed1988

The effect of hyperbaric oxygen on cerebral hemoglobin oxygenation and dissociation rate of carboxyhemoglobin in anesthetized rats: spectroscopic approach.

By measuring near-infrared transmittance spectra, we examined the effect of HBO on cerebral Hb oxygenation in normal and ischemic brain in the anesthetized rat. The oxygenation state of Hb was around 80% in the rat brain under 1 ATA air breathing. HBO did not induce further cerebral Hb oxygenation above 2 ATA in control animals but improved tissue oxygenation in the ischemic brains. The oxidation-reduction state of cyt. aa3 in the normal brain was not affected by HBO. In the ischemic brain, however, HBO prevented ischemia-induced reduction of cyt. aa3. Non-invasive optical monitoring of COHb with visible reflectance spectrophotometry was also examined. HBO markedly accelerated dissociation of COHb. Tight correlation was found between the optical signal and COHb content determined from blood samples. These results demonstrated the usefulness of optical monitoring in vivo under hyperbaric conditions.

Anaerobiosis↗