Biomedical subjects

E Sakurai

Publications and source records attributed to E Sakurai.

148 records · Page 9Linked to original sources

PubMedDate not supplied

Effect of particle size of polymeric nanospheres on intravitreal kinetics.

In this study, we injected nanospheres containing a fluorescein derivative into the vitreous cavity of pigmented rabbit eyes and evaluated their intraocular kinetics as drug carriers in vivo. Polystyrene nanospheres (2 microm, 200 nm and 50 nm in diameter) containing a fluorescein derivative were used in this study. A suspension of each particle was prepared by diluting with distilled water at a concentration of 10 microg/ml equivalent to sodium fluorescein. The suspension of nanospheres was injected once into the vitreous cavity of unilateral eyes of pigmented rabbits. A sodium fluorescein solution of the same concentration was injected once into the vitreous cavity of the other eye as the control. The intraocular kinetics of nanospheres was evaluated by measuring vitreous fluorescence using a scanning fluorophotometer. To investigate elimination pathways of nanospheres in detail, serial cross-sections of the eyes were examined with a fluorescence microscope. The fluorescence derived from nanospheres was observed in the vitreous cavity for over 1 month (2 microm: t(1/2) = 5.4 +/- 0.8 days, 200 nm: t(1/2) = 8.6 +/- 0.7 days, 50 nm: t(1/2) = 10.1 +/- 1.8 days), whereas that in the control eyes completely disappeared within 3 days (t(1/2) = 7.8 +/- 0.7 h). The elimination half-life from the vitreous cavity correlated well with the particle diameter (r = -0.997, p = 0.007). Histological studies using a fluorescence microscope revealed that nanospheres with a diameter of 2 microm were seen in the vitreous cavity and trabecular meshwork, while nanospheres with a diameter of smaller than 200 nm were also observed in the retina as well as these tissues. Our findings indicated that nanospheres may be beneficial as a drug carrier to the retina, vitreous and trabecular meshwork.

Animals↗

PubMedDate not supplied

[Diarrhea and biogenic amines: regional changes in brain histamine concentration and serotonin metabolism following castor oil-induced diarrhea in rats].

Regional changes in concentrations of histamine (HA), serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) in the rat brain were investigated after diarrhea induced by castor oil. Significant decreases in body weight were observed from the 3rd day after daily oral administration of castor oil (2.5 ml/kg). HA concentrations in most brain regions decreased in diarrhea induced by a single administration of castor oil. A significant decrease was recognized particularly in the case of the hippocampus. The influence has begun to appear in the thalamus and hypothalamus in consecutive (3 d) administration. HA concentration in the striatal and hypothalamic regions of the rat treated with castor oil for 9 d significantly decreased in comparison with the control group. On the other hand, an inhibition of 5-HT turnover was observed in the thalamus at 3 h after a single administration of castor oil. However, this inhibition was not found in rats treated with castor oil for 3 d. Moreover, 5-HT concentration in the midbrain significantly decreased in rats that acquired the adaptability for the occurrence of diarrhea. These data present a new finding that the occurrence of diarrhea or acquisition of adaptability for diarrheal occurrence affects the central histaminergic or serotonergic neuron system.

Animals↗

PubMedDate not supplied

[Maps of epidemiological rates: a Bayesian approach].

This article presents statistical methods recently developed for the analysis of maps of disease rates when the geographic units have small populations at risk. They adopt the Bayesian approach and use intensive computational methods for estimating risk in each area. The objective of the methods is to separate the variability of rates due to differences between regions from the background risk due to pure random fluctuation. Risk estimates have a total mean quadratic error smaller than usual estimates. We apply these new methods to estimate infant mortality risk in the municipalities of the State of Minas Gerais in 1994.

Bayes Theorem↗

PubMedDate not supplied

[Accuracy of MiniWright peak expiratory flow meters]

OBJECTIVE: To evaluate the accuracy of the Mini-Wright (Clement Clarke International Ltd.) peak-flow meters. METHODS: Twenty of those meters were checked by use of electronic calibration syringe (Jones Flow-Volume Calibrator(R)). Nine of them had an old scale, with values displayed equidistantly, and eleven had a new mechanical scale with non-equidistant values. Each device was connected in series to the calibration syringe to perform eight hand-driven volume injections, with flows ranging from 100 to 700 l/min. Absolute and relative differences between meters and syringe were calculated, the syringe values taken as standard. The accuracy of the twenty Mini-Wright devices was validated by the American Thoracic Society criteria (-/+ 10% or -/+ 20 l/min), and/or European Respiratory Society criteria (-/+ 5% or -/+ 5 l/ min). RESULTS: New scale instruments were more accurate than old scale meters (p < 0.001), by both ATS and ERS criteria. Every meter was rechecked after 600 measurements. Both the old, and the new scale instruments maintained the same level of performance after this evaluation. CONCLUSIONS: Results suggest that new scale meters were accurate and can be safely used in clinical practice. The authors strongly recommend that they are rechecked regularly to ensure that they are within the ATS and ERS variation limits.

Journal Article↗