Preclinical Evaluation of an Everolimus-Eluting Bioresorbable Vascular Scaffold Via a Long-Term Rabbit Iliac Artery Model

BACKGROUND@#Biodegradable poly (l-lactic acid) (PLLA), a bio safe polymer with a large elastic modulus, is widely used in biodegradable medical devices. However, because of its poor mechanical properties, a PLLA strut must be made twice as thick as a metal strut for adequate blood vessel support. Therefore, the mechanical properties of a drug-eluting metal-based stents (MBS) and a bioresorbable vascular scaffolds (BVS) were evaluated and their safety and efficacy were examined via a long-term rabbit iliac artery model. @*METHODS@#The surface morphologies of the MBSs and BVSs were investigated via optical and scanning electron microscopy. An everolimus-eluting (EE) BVS or an EE-MBS was implanted into rabbit iliac arteries at a 1.1:1 stent-toartery ratio. Twelve months afterward, stented iliac arteries from each group were analyzed via X-ray angiography, optical coherence tomography (OCT), and histopathologic evaluation. @*RESULTS@#Surface morphology analysis of the EE coating on the MBS confirmed that it was uniform and very thin (4.7 lm). Comparison of the mechanical properties of the EE-MBS and EE-BVS showed that the latter outperformed the former in all aspects (radial force (2.75 vs. 0.162 N/mm), foreshortening (0.24% vs. 1.9%), flexibility (0.52 vs. 0.19 N), and recoil (3.2% vs. 6.3%). At all time points, the percent area restenosis was increased in the EE-BVS group compared to the EE-MBS group. The OCT and histopathological analyses indicate no significant changes in strut thickness. @*CONCLUSION@#BVSs with thinner struts and shorter resorption times should be developed. A comparable long-term safety/efficacy evaluation after complete absorption of BVSs should be conducted.

Immunohistochemical study on cytokeratin expression on developing tongue in Korean native goats (Capra hircus) / 동물의과학연구지

Cytokeratin (CK) comprises the intermediate filament cytoskeleton of epithelial cells. Patterns of CK expression can be regarded as a specific marker for epithelial differentiation status. The aim of this study was to identify CK expression on tongues of Korean native goats ranging from 60-day-old fetuses to newborns during prenatal development using immunohistochemistry. The tongues of fetuses were removed from 2- to 4-year-old female Korean native goats by caesarean section performed under general anesthesia. Immunohistochemistry was performed to assess CK expression patterns on developing goat tongues using serial paraffin-embedded sections. Light zones signifying CK immunoreactivity in dorsal lingual epithelia were weakly positive in 60-day-old fetuses. In 90-day-old fetuses, deep areas in dorsal lingual epithelia were strongly positive for CK expression and superficial areas were moderately positive. In 120-day-old fetuses, light zones of lingual epithelia in the vallate papilla were strongly positive for CK expression, whereas ducts of von Ebner's glands were moderately positive. In neonates, taste buds were positive for CK expression, whereas non-taste epithelial cells and von Ebner's glands were negative. These findings indicate that goat tongues have different patterns of CK expression during development and provide a morphological basis for studies on the biological mechanism of epithelial differentiation.

Scanning electron microscopic observation of lingual papillae in a Bengal tiger (Panthera tigris tigris) / 동물의과학연구지

The morphology of the lingual papillae in a female Bengal tiger (Panthera tigris tigris) was examined by scanning electron microscopy (SEM). The tongue was 22.3 cm in length and 7.1 cm in width. Numerous filiform papillae were distributed over the entire dorsal surface of the tongue. SEM examination of the tongue revealed two types of mechanical papillae, i.e. filiform and conical papilla, and two types of gustatory papillae, i.e. fungiform and vallate papilla, on the dorsal surface of the tongue. Each filiform papilla consisted of one primary papilla and several secondary papillae. The filiform papillae on the anterior part of the tongue were divided into one primary and 6~14 secondary papillae. Unlike other mammalians, however, secondary papillae in the mid-part of the tongue showed pineal-like papillae. In the posterior part of the tongue, secondary papillae were rare or absent. Fungiform papillae were surrounded by filiform papillae and densely distributed on the lingual surface. There were two vallate papillae on the borderline between the lingual body and root of the tongue. A vallate papilla contained two secondary papillae inside the grooves. Conical papillae were located in the area of the vallate papillae and covered the posterior part of the tongue root. No foliate papillae were seen on both margins of the posterior part of the tongue. Our results indicate that the structure on the lingual papillae of the Bengal tiger is somewhat different from that of other mammals.

A light microscopic study on tongue development in Korean native goats (Capra hircus) / 동물의과학연구지

The purpose of this study was to identify the composition and organization of lingual tissues underlying the histo-structural change of developing tongue in Korean native goats by light microscopy (LM). Tongues of the fetuses on days 60, 90, 120 and neonate were examined for the morphological development. In the 60-day-old fetuses, the tongue tissues were differentiated into epithelium, lamina propria and muscle layer. Primordia of filiform, conical, lentiform, fungiform and vallate papillae appeared and rudiments of taste bud were observed in the epithelia of the primordia of the gustatory papillae. The dorsal surface of the lingual epithelia showed a weak PAS positive reaction. Collagenous fibers and small blood vessels were shown in the connective tissues. In the 90-day-old fetuses, Von Ebner's glands were moderately PAS positive while the muscle fibers and connective tissue were strongly positive for PAS. The collagenous fibers increased and came to have a more complex arrangement in the tongue. The muscle fibers were spread out at various directions and developed in striated muscle bundles. In the 120-day-old fetuses, taste buds were observed in the epithelia of the gustatory papillae, and several well-developed tissues visible such as blood vessels, collagenous fibers, muscle fiber bundles and Von Ebner's glands. In the neonates, many taste buds were found in a transverse section of the vallate papilla. The muscle layers, Von Ebner's glands, collagenous fibers and blood vessels were more developed than those of the 120-day old fetuses. These findings indicate that goat tongues have a variety of different shapes during prenatal development.

Scanning electron microscopic structure of lentiform papillae on tongues of developing Korean native goats (Capra hircus) / 동물의과학연구지

The purpose of this study was to explore the morphological characteristics of developing lentiform papilla (LP) in Korean native goats by scanning electron microscopy (SAM). Tongues were removed from fetuses on days 90, 120, neonates, and juveniles on days 30, 60, 90, 120, 150, and 180. In prenatal development, the primordia of LP in 90-day-old fetuses were round and spotted on the inner most part of the torus linguae of the tongue. Primordia of LP in 120-day-old fetuses also had a lens-like shape. In neonates, LP displayed similar features as the adult one. In postnatal juveniles on days 30 and 60, LP continually increased in size without much difference in structure compared to that of neonates. By postnatal day 90, detached pieces of keratinized superficial epithelia were observed. Microridges and microplicae were well developed on the epithelial surface of LP in 60- to 120-day-old goats. The lengths of LP were 476~514 microm in neonates, 687~962 microm in the weaning period of 60-day-old goats, and 1,068~1,567 microm in the maturing period of 180-day-old goats. These findings indicate that goat LP has different sizes and shapes from those of other species during development.