Kazuhiko Shirama

Enhancement of Apoptosis in Developing Chick Neural Retina Cells by Basic Fibroblast Growth Factor

Abstract: To evaluate the role of various growth factors in naturally occurring cell death during development of the neural retina, we examined the effects of such factors on the nuclear morphology and the size of DNA in cultured chick embryonic neural retina cells. Basic fibroblast growth factor (bFGF) increased internucleosomal cleavage of DNA and nuclear fragmentation in a time‐ and dose‐dependent manner. The effect was inhibited by anti‐bFGF antibody, suramin, and cycloheximide. Epidermal growth factor, platelet‐derived growth factor, nerve growth factor, tumor necrosis factor‐α, and dexamethasone had no effect. These results provide evidence that bFGF may eventually act as a lethal factor inducing apoptotic cell death during the development of the neural retina in chick embryo.

Effects of Endocrine Glands and Hormone Replacement on the Mast Cell Count of the Harderian Gland of Mice

There are marked sex differences in the Harderian gland of the C3H/He mouse strain, the females having a larger number of mast cells than the males as one of the major differences. Mast cell counts of the Harderian gland were made on male mice subjected to combinations of adrenalectomy, gonadectomy and administration of sex steroid hormones. Castration alone caused a significant increase in the count resulting in about three times the number found in intact males. Castration plus adrenalectomy increased the count over 6-fold, to levels close to those found in female mice. Administration of testosterone or estrone to the mice which had been castrated and adrenalectomized prevented the increase, while progesterone treatment had no effect on the count. Although the number of mast cells in the male Harderian gland was necessarily small compared to either the female gland or that of castrated and adrenalectomized males, no obvious dimorphism could be found microscopically.

Molecular and virulence characteristics of an outer membrane-associated RTX exoprotein in Pasteurella pneumotropica

BackgroundPasteurella pneumotropica is a ubiquitous bacterium that is frequently isolated from laboratory rodents and causes various clinical symptoms in immunodeficient animals. Currently two RTX toxins, PnxIA and PnxIIA, which are similar to hemolysin-like high-molecular-weight exoproteins are known in this species. In this study, we identified and analyzed a further RTX toxin named PnxIIIA and the corresponding type I secretion system.ResultsThe RTX exoprotein, PnxIIIA, contains only a few copies of the RTX repeat-like sequence and 3 large repeat sequences that are partially similar to the outer membrane protein found in several prokaryotes. Recombinant PnxIIIA protein (rPnxIIIA) was cytotoxic toward J774A.1 mouse macrophage cells, whereas cytotoxicity was attenuated by the addition of anti-CD11a monoclonal antibody. rPnxIIIA could bind to extracellular matrices (ECMs) and cause hemagglutination of sheep erythrocytes. Binding was dependent on the 3 large repeat sequences in PnxIIIA. Protein interaction analyses indicated that PnxIIIA is mainly localized in the outer membrane of P. pneumotropica ATCC 35149 in a self-assembled oligomeric form. PnxIIIA is less cytotoxic to J774A.1 cells than PnxIA and PnxIIA.ConclusionsThe results implicate that PnxIIIA is located on the cell surface and participates in adhesion to ECMs and enhanced hemagglutination in the rodent pathogen P. pneumotropica.

Harderian Glands and Their Development in Laboratory Rats and Mice

The Harderian glands of the rat and mouse lie, for the most part, deep within the orbit. However, the external rim of the gland extends forward into the space between the bulbus oculi and the orbital rim, and can be seen as soon as the palpebral fascia has been removed from its orbital attachment. The gland consists of two portions, a smaller lobule occupying the upper portion of the eye socket, and a lower, larger and more diffuse lobule occupying the floor of the optic cavity. As there is no marked histological difference between the lobules, they can be considered together as a single entity. The glands of rats and mice are characterized by the production of porphyrins and its accumulation within the glandular lumina. The function of the gland remains unknown, although it is usually regarded as a source of lubrication and protection for the cornea. The purpose of this section is to summarize what has been reported to date on the Harderian glands of rats and mice.

Postnatal development of the harderian gland in the rabbit: Light and electron microscopic observations

We have investigated the development of the Harderian glands of Japanese white rabbits from birth to 4 months of age. Although two types of secretory cells comprise the glandular epithelium of the pink and white lobes in fully developed glands, the time of neonatal appearance is different between the two. Cells consisting of the pink lobe first appear on the third day of life, while cells of the white appear around seventh day of life. The ultrastructure of the Harderian glands from 1‐week‐old rabbits resembles that of adult animals. The gland can be divided into three parts on the basis of their epithelial cell composition at the electron microscopic level. The respective parts are composed of: (1) one type of cells with large vacuoles (pink lobe), (2) one type of cells with small vacuoles (white lobe), and (3) two types of cells with large and small vacuoles (pink‐white mixed portion).

Fine Structure of Melanocytes and Macrophages in the Harderian Gland of the Mouse

The presence of dendritic cells containing melanin granules has been demonstrated employing silver impregnation and electron microscopy in the interstitial tissue of the Harderian gland of the mouse. Two types of melanocytes, either with or without the various developmental stages of melanin granules, were found in the gland. Cells with developing granules were more dendritic and contained a large number of cytoplasmic organelles. The other cells were ellipsoidal or slender in shape and contained few cytoplasmic organelles and a large number of fully melanized granules, but no developing granules. In general, the granules of the Harderian gland melanocytes resembled granules from other organs (particularly the skin of the eyelids). The general size range of the granules was 0.2-0.9 micron. Each granule was enclosed by a membrane. The Harderian gland macrophages contained fully pigmented melanin granules of various sizes. The granules were enclosed by a membrane either singly or in groups. Some of the melanin granules within the phagosomes showed signs of degradation, revealing the underlying matrix.

Expression of genes encoding antimicrobial peptides in the Harderian gland of the bullfrog Lithobates catesbeianus.

The Harderian gland is an orbital gland found in many tetrapod species that possess a nictitating membrane. While the main role of the Harderian gland is lubrication of the eyeballs, numerous other functions are attributed to this gland. In amphibians, mast cells have been detected in the Harderian gland, suggesting that the gland is involved in the hosts system of innate immunity defending against microbial invasions. Using reverse-transcription polymerase chain reaction, we cloned from the bullfrog Harderian gland total RNA preparations, cDNAs encoding biosynthetic precursors for the antimicrobial peptides temporin-CBa (FLPIASLLGKYL-NH2), previously isolated from an extract of bullfrog skin, and chensirin-2CBa (IIPLPLGYFAKKP) that contained the amino acid substitution Thr13-->Pro compared with chensirin-2 from the Chinese brown frog, Rana chensinensis. By means of in situ hybridization using digoxigenin-labeled cRNA probes for preprotemporin-CBa and preprochensirin-2CBa, we have demonstrated for the first time in an amphibian the presence of mRNAs encoding these two precursors in the cytoplasm of the glandular cells in the bullfrog Harderian gland.

Natural vanadium-containing Mt. Fuji ground water improves hypo-activity of liver insulin receptor in Goto-Kakisaki rats

After daily treatments with Mt. Fuji ground water containing natural vanadium (approximately 65 μg/l) at doses of 0.53 μg/kg/day for 12 weeks, blood glucose (BG), serum hemoglobin A1C (HbA1C) levels and insulin secretion from the pancreas of Goto-Kakisaki (GK) rats, a genetic model of Type 2 diabetes, were improved. In GK rat liver insulin receptors, the binding properties of [125I] insulin, and the activities of insulin receptor β subunit and primary insulin-like growth factor-1β all recovered to normal levels of those found in Wistar rats. These results suggest that daily treatment with small concentrations of natural vanadium improves hyperglycemia by ameliorating liver insulin receptor activity. (Mol Cell Biochem 267: 203–207, 2004)

Clearance of Materials from Breakdown of Uterine Collagen in Mice during Postpartum Involution

The collagen content of the mouse uterus increases during pregnancy and rapidly decreases to the level of nulliparous mice within a few days post partum. Most of the hydroxyproline in the uterine collagen had disappeared by day 3 post partum. During postpartum involution the hydroxyproline concentration in both the serum and blood clot was not higher than in nulliparous mice. The total hydroxyproline content in the liver, spleen and thymus was significantly increased during postpartum involution. These results indicate that materials derived from the breakdown of uterine collagen are rapidly removed from the blood stream by reticuloendothelial clearance.

Cytoarchitectonic subdivisions of the parabrachial nucleus in the Japanese monkey (Macacus fuscatus) with special reference to spinoparabrachial fiber terminals

The cytoarchitectonic subnuclear organization of the parabrachial nucleus (PB) surrounding the brachium conjunctivum (BC) in the monkey was examined using the Nissl method and the anterograde axonal flow method. PB of the monkey could be divided into the following subnuclei: the dorsal area (DPBM) along the medial surface of the medial three-fourths of BC in the caudal half of medial PB (PBM), the ventral area (VPBM) along the medial surface of the lateral one-fourth of BC in the rostral two-thirds of PB, the ventrolateral part of lateral PB (PBL) lateral to BC throughout PB (EL), the ventral part of the rostral half of PBL ventral to EL (EXL), the medial part of middle PBL along the dorsal surface of BC (VL), the dorsal and lateral marginal part of PBL in the rostral two-thirds of PB (DL), the cell cluster in the dorsomedial part of the rostral half of PBL between VL and DL (CL), the dorsocentral part appearing at the level of root exit of the trochlear nerve between DL and CL and extending to the rostral end of PBL (IL), the area between DL and IL in the rostral one-seventh of PBL (SL), and Kölliker-Fuse nucleus (KF) ventral to EL and BC in the middle one-third of PB and lateral to the lateral pontine tegmentum. After the injection of biotinylated dextran amine into the upper cervical segments, labeled fibers terminated in each subdivision of PB with different densities; most heavily in IL, more heavily in DL and KF, moderately in EL and VPBM, and scarcely in the rest of PB. The present study demonstrated for the first time the subdivisions of PB in the monkey, which were essentially common to those of the rat based on the cytoarchictecture of PB and spinal fiber terminals in it.