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Biomedical subjects

T Yotsuyanagi

Publications and source records attributed to T Yotsuyanagi.

At least 109 records · Page 6Linked to original sources
PubMed1976

Systems approach to vaginal delivery of drugs II: In situ vaginal absorption of unbranched aliphatic alcohols.

The absorption of unbranched aliphatic alcohols in the rabbit vagina was studied using a perfusion method, and the absorption rates were found to be first order with respect to the drug concentration in the vagina from methanol to octanol. A physical model involving an aqueous diffusion layer in series with a membrane consisting of aqueous pores and lipoidal pathways was used for analyzing the data. The physically based parameters in the model were determined. An effective diffusion layer thickness ("unstirred layer") of around 0.035 cm was found. The increase in the permeability coefficient for the lipoidal pathway per methylene group was around 2.5 for this homologous series.

Absorption↗
PubMed1975

Systems approach to vaginal delivery of drugs I: development of in situ vaginal drug absorption procedure.

In the framework of the development of drug delivery systems for locally administered contraceptive drugs, a reliable method that can afford quantitative evaluation of drug absorption behavior was explored using the rabit doe. A system was constructed based upon perfusing the drug solution in the vaginal tract. For this purpose, a "rib-cage" type cell was constructed and surgically implanted in the rabbit prior to an experiment. The primary purpose of the present paper is to evaluate the method, including the surgical operation and the perfusion system. The absorption experiments were carried out using n-butanol-1minus 14C as the model solute to survey the reproducibility of the absorption behavior. Experiments were conducted with a number of rabbits on several successive days to determine the day-to-day and animal-to-animal variations. The drug disappearance in the reservoir followed first-order kinetics from which the apparent permeability coefficient was calculated. The results indicated that a set of experiments may be carried out on a single animal and that the method generally affords rather high precision.

Absorption↗
PubMedDate not supplied

Aesthetic reconstruction for large upper lip defects in men.

Although many techniques use hair-bearing flaps to repair large upper lip defects in men, few preserve orbicularis sphincter function. Available techniques can also result in an unnatural appearance, because the entire upper lip is covered by a dense region of hair. We have developed a new technique and successfully repaired a large defect in the upper lip of three men. This technique uses flaps pedicled by angular vessels and includes the orbicularis oris muscle. A good outcome can be obtained both functionally and cosmetically when used in men with defects involving more than one-half of the upper lip.

Adult↗
PubMedDate not supplied

The relationship between prostaglandin E1 applied area and flap survival rate.

Using a silicone gel sheet continuous drug delivery system containing Prostaglandin E1 (PGE1), the relationship between flap survival rate and the site of drug application was studied. Skin flaps measuring 2 x 9 cm were raised on the dorsum of rats, and divided into 3 areas. Area 1 was within 3 cm of the flap tip, area 2 was between 3-6 cm from the flap tip including the critical zone, and area 3 was the portion within 4 cm of the flap base. Further, area 4 was a strip of skin around the flap, 1 cm in width. Compared to the control group, a significant increase in flap survival rate was seen only when PGE1 was administered to area 2 (p < 0.01, t-test). Specimens injected with dye intravascularly showed an increase in the number of thick vessels in area 3, when PGE1 was applied only to area 3. However, when PGE1 was applied to area 2, there was no significant vascular increase in area 3. Instead, an extensive network of fine vessels was observed in area 2.

Alprostadil↗
PubMedDate not supplied

Astrocytic contributions to blood-brain barrier (BBB) formation by endothelial cells: a possible use of aortic endothelial cell for in vitro BBB model.

Astrocytic contribution of endothelial cell monolayer permeability was examined in two blood-brain barrier (BBB) models, using the coculture in a double chamber system: rat astrocytes and bovine aortic endothelial cells (BAECs) or bovine brain endothelial cells (BBECs). In system 1, where astrocytes were separated from endothelial cells, a 40% reduction in L-glucose permeability of the BBEC monolayer, but not the BAEC monolayer, was observed by cocultivation with astrocytes. Although several passages of BBEC in culture elicited morphological transformation from spindle-shapes to cobblestone-like features, the passaged BBECs remained responsive to astrocytes in coculture in system 1 (37% reduction of the L-glucose permeability). By contrast, in system 2, where respective endothelial cells and astrocytes layered on the upper and lower surfaces of a membrane, the permeability of both BAEC and BBEC monolayers was reduced by cocultivation with astrocytes (75% reduction for BAEC and 40% reduction for BBEC). BAECs in this contiguous coculture (system 2) with astrocytes showed numerous tight junction-like structures characteristic of the BBB in vivo. These results suggest that primary cultured BBECs, which had been primed by astrocytes in vivo, retain a higher sensitivity to astrocytes possibly through an astrocytic soluble factor (s) to exhibit BBB-specific phenotypes, and that even BAEC from extra-neural tissues, when cultured with astrocytes in close proximity in vitro, may acquire the similar phenotypes and serve for an extensive use of BBB model in vitro.

Animals↗