Masahisa Shimada

Free radical production by the red tide alga, Chattonella antiqua.

SummaryThe red tide alga,Chattonella antiqua, was found to show a strong chemiluminescence, using luminol as the reagent, when exposed to ultraviolet irradiation. This luminescence was completely inhibited by ascorbate or catalase, suggesting that hydrogen peroxide was generated by the plankton. Red tide cells exposed to fish gill mucus from young yellowtail resulted in the release of a large number of mucocysts and a weak luminosity, and showed a strong reduction of cytochromec in the medium. Therefore, the discharge of mucocysts from the red tide, induced by the presence of gill mucus, may be accompanied by the release of active oxygen species. The active oxygen may be involved in depolymerization of mucus glycoproteins from the gill lamellae.

The fibers which leave the Probst's longitudinal bundle seen in the brain of an acallosal mouse: a study with the horseradish peroxidase technique

The congenital absence of the corpus callosum, a brain anomaly frequently noted in humans, has been recently found to occur in some mice of the ddN strain in our laboratory. In the brains of these mice, the Probsts longitudinal bundle is always present on both cerebral hemispheres and gives rise to some aberrant fibers toward the midline. In this research, the neuroanatomical features of these fibers were studied by iontophoretical injections of horseradish peroxidase (HRP) into the neocortex of acallosal mouse brains. The results revealed that the fibers which leave the Probsts longitudinal bundle are, at least, of 3 kinds: namely, the fibers that run out from the anterior portion of the bundle and take a U-turn ipsilaterally without crossing the midline through the septal tissue to go back again into the longitudinal bundle at the level where they have left it; the commissural fibers that leave the bundle from its middle portion and cross through a tiny bridge of tissue associated with the ventral hippocampal commissure to the opposite hemisphere; and the fibers that arise from the posterior portion of the bundle and accumulate as an anomalous fascicle below the cingulum. The observation that no labeled fibers were seen within the anterior commissure in the present HRP materials suggests that the axons from neocortex which are prevented from crossing the midline in mice with congenital absence of the corpus callosum cannot find an alternative pathway via the anterior commissure.

Estimation of age from the femur of Japanese cadavers

The purpose of this study is to estimate the age of cadavers by histomorphometry of the femur. Seventy-two Japanese males ranged from 43 days to 92 years old and 26 females ranged from 2 to 88 years old were used. The thickness of sections was adjusted at 50 to 70 microns by grinding with sand paper. The sections were not decalcificated. They were stained with Villanuevas bone staining powder and with thionin dye. Microradiographs of the sections were obtained by the soft X-ray apparatus. The area, maximum and minimum diameter, and perimeter of the perfect osteon and Haversian canal were measured. In addition, the type II osteon number, osteon fragment number, and area of triangle were also determined. All these parameters were examined by an image analyzer. The parameters of the osteon showed high correlation coefficient with age (magnitude of r > 0.77), while those of the Haversian canal were low (magnitude of r < 0.11). All parameters were subjected to multiple regression analysis for producing a multiple regression equation of age estimation. For the stepwise selecting method, the perimeter of osteon, maximum length of the Haversian canal and osteon fragment number were selected for the equation. Their multiple r2 and standard error of estimation were 0.8874 and 6.39, respectively. For the forward selection method, in addition to the above items, three parameters, the maximum length of Haversian canal, triangle area, osteon fragment number were selected. Their multiple r2 and standard error of estimation were 0.9484 and 4.884, respectively. Bone staining was useful to clarify the demarcation between osteon and fragment, leading to an increase in the accuracy of age estimation. However, the entire range from birth to 90 years was difficult to cover for precise age estimation.

Histologic distribution of insulin and glucagon receptors

Insulin and glucagon are the hormonal polypeptides secreted by the B and A cells of the endocrine pancreas, respectively. Their major physiologic effects are regulation of carbohydrate metabolism, but they have opposite effects. Insulin and glucagon have various physiologic roles, in addition to the regulation of carbohydrate metabolism. The physiologic effects of insulin and glucagon on the cell are initiated by the binding of each hormone to receptors on the target cells. Morphologic studies may be useful for relating biochemical, physiologic, and pharmacologic information on the receptors to an anatomic background. Receptor radioautography techniques using radioligands to label specific insulin and glucagon receptors have been successfully applied to many tissues and organs. In this review, current knowledge of the histologic distribution of insulin and glucagon receptors is presented with a brief description of receptor radioautography techniques.

The distribution of 14c from [U-14c]glucose in mice using whole-body autoradiography.

Tissue distribution of radioactive carbon from [U-14C]glucose in the mouse in vivo was studied by whole-body autoradiography. The mice were frozen with Dry-Ice-acetone at 0.5, 1, 5 and 30 min, 1 and 24 hr and 1 and 3 weeks after intraperitoneal injection of [U-14C]glucose. Whole-sagittal sections of the frozen mouse, obtained by using a microtome in a cryostat, were dried in a cryostat and autoradiographed. The resulting dry autoradiographs are called untreated autoradiographs in the present work. The sections were then fixed in cold 6% (w/v) HClO4, dried at room temperature and again autoradiographed. Autoradiographs that have undergone this process are referred to as treated autoradiographs. In both untreated and treated autoradiographs, within 1 min following injection of the labeled glucose, the abdominal cavity had the highest autoradiographic density. At 1 hr, density became highest in Harders, sublingual and duodenal glands, large intestinal mucosa and tongue, and after 3 weeks, no autoradiographic denisty was present.

The fibers which course within the Probst's longitudinal bundle seen in the brain of a congenitally acallosal mouse: a study with the horseradish peroxidase technique

The congenital absence of the corpus callosum, a brain anomaly frequently noted in humans, has been recently found to occur in some mice of the ddN strain in our laboratory. In the brains of these mice, the Probsts longitudinal bundle is always present on both cerebral hemispheres. In this research, the neuroanatomical features of the constituent fibers of this bundle were studied by iontophoretical injections of horseradish peroxidase into different loci in the neocortex of acallosal mouse brains. The results revealed that (1) certain cortical fibers of the Probsts bundle terminate in the ipsilateral neocortex; (2) some commissural fibers in the longitudinal bundle originate from the cells in the wide neocortical regions, and project to the opposite hemisphere in homotopic as well as heterotopic regions over the ventral hippocampal commissure; (3) the fibers from different cortical regions are arranged in a topographic manner within this bundle. The present data clearly demonstrate that a good portion of fibers in the Probsts longitudinal bundle seen in the congenitally acallosal mouse brain are corticocortical in nature, which indicates that this bundle has an ipsilateral neocortical association function.

INCORPORATION OF 14C FROM [U-14C]GLUCOSE INTO FREE AMINO ACIDS IN MOUSE BRAIN LOCI IN VIVO UNDER NORMAL CONDITIONS

By macroautoradiography and by GLC separation, differences in the uptake of radioactive carbon from [U‐14C]glucose into free amino acids (glutamate + glutamine, aspartate + asparagine, GABA, alanine and glycine) in mouse cerebral neocortex, hippocampus, thalamus and hypothalamus were investigated.

Immunohistochemical localization of calcineurin, calmodulin-stimulated phosphatase, in the rat hippocampus using a monoclonal antibody

Immunohistochemical localization of calcineurin, a calmodulin-stimulated phosphatase, was examined in the rat hippocampus by using a monoclonal antibody VD3 which is specific for the A subunit (61 kDa) of calcineurin. The stratum lucidum, where the mossy fiber terminal forms giant synaptic boutons, showed strong immunoreactivity.

The Distribution of Tissue Insulin Receptors in the Mouse by Whole – Body Autoradiography

The distribution of insulin binding sites in the mouse was investigated by in vivo whole-body autoradiography. Male mice were injected intravenously with 125I-insulin in the absence of and, in the presence of, excess unlabeled insulin. Three, 6, 15, 30 and 60 minutes after injection, the animals were perfused and subjected to autoradiographic procedures. Specific insulin binding was observed in the choroid plexus, liver, gastrointestinal tract, spleen, pancreas, deferent duct, and Harderian gland. In the liver and spleen, the distribution of binding sites was heterogeneous. In the liver, the density of the binding was higher around the branches of the portal vein than around the central vein. In the spleen, the marginal zone exhibited a higher density than the white and red pulp. The kidney cortex, and the thyroid gland showed a high degree of insulin binding, but the binding was nonspecific. The binding of insulin to other tissues and organs, including the skeletal muscle and fat, was weak, and most of the binding was nonspecific.

Agenesis of the corpus callosum in ddN strain mouse associated with unusual facial appearance (flat-face)

In the course of an experiment involving brother-sister matings between ddN strain mice, mice occurred with an unusual facial appearance (flat-face). Subsequently, 4 mice with flat-face were bred from the litters of the second birth (ca. 10% frequency). This flat-face was assumed to be the result of a malformed short nose, hypoplastic maxilla and mandible, and hypertelorism. These 4 flat-face mice exhibited no significant delays in growth, motor ability or the development of learning ability. Histologically, they were all characterized by an almost total absence of callosal fibers and the presence of abnormal longitudinal neuromatous bundles. Therefore, the flat-face mice may be useful as experimental animals for brain research, as one can easily judge that they lack the corpus callosum from the facial appearance.