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The SAMP10 mouse is a model of accelerated ageing in which senescence is characterized by age-related atrophy of the cerebral cortex and limbic structures, poor learning and memory task performance with depressive behaviour and cholinergic and dopaminergic alterations. Here we studied age-related changes in the dendritic arbors and spine density of pyramidal cells in the medial prefrontal cortex of SAMP 10 mice using a quantitative Golgi method. Dendrites of prefrontal neurones gradually retracted with ageing towards the soma with the relative preservation of overall complexity. Apical dendrites were much more severely affected than basal dendrites. The combined length of the apical dendrites and spine density were decreased by 45% and 55%, respectively, in mice at 12 months, compared with mice at 3 months of age. Immunohistochemical and immunoblot analyses indicated that expression of microtubule-associated protein (MAP) 2, a marker of dendrites, decreased in an age-related manner not only in the anterior cortex but also in the posterior cortex and olfactory structures in SAMP10 mice. Decreased expression of MAP2 mRNA caused the decrease in MAP2 protein expression. These results suggest that retraction of apical, but not of basal dendrites, with a loss of spines in prefrontal neurones, appears to be responsible for poor learning and memory performance in aged SAMP 10 mice. It is also suggested that age-related dendritic retraction occurs in a wide area including the entire cerebral cortex and olfactory structures.

Chondroitin sulfate proteoglycans have been shown to participate in the pathogenesis of neuronal damages in the injured adult central nervous system (CNS). Upregulated expression of chondroitin sulfate proteoglycans has been reported around the injured sites and depletion of these chondroitin sulfate proteoglycans brings about increased axonal regeneration in the injured adult CNS. To examine if chondroitin sulfate proteoglycans are also involved in the pathologic process of hypoxia-ischemia in the neonatal brain, expressions of three chondroitin sulfate proteoglycans, neurocan, phosphacan, and neuroglycan C, were examined in rat brains after neonatal hypoxia-ischemia. Hypoxic-ischemic rats were produced by ligating the right carotid artery of 7-day-old rats, followed by 8% oxygen exposure. Western blot analysis revealed that in contrast to injured adult CNS, the amount of neurocan was reduced 24 hr after hypoxia in the neonatal hypoxic-ischemic cerebral hemisphere. The amounts of phosphacan and neuroglycan C were also reduced significantly 24 hr after hypoxia at the right injured cortex compared to those at the left cortex. Surprisingly, the immunohistologic staining for phosphacan was conversely intensified both at 24 hr and 8 days after hypoxia at the infarcted area. In addition, the habenula and fascicules retroflexus in the right cerebral hemisphere degenerated and became intensely immunostained with the anti-phosphacan antibody shortly after hypoxia. Hypoxic-ischemic insult may unmask phosphacan epitopes at the injured sites, resulting in intensified immunostaining. Because intensified immunostaining for neurocan and neuroglycan C was not observed, unmasking seems to be specific to phosphacan among these three chondroitin sulfate proteoglycans.

Bilateral, symmetrical, experimental aneurysms were produced with anastomosed vein flap in the carotid arteries of 24 mongrel dogs. Aneurysms were occluded with latex or silicone balloons on each side and observed angiographically from 2 weeks to 2 months. A histopathological study was performed subsequently using light and scanning electron microscopy. Rupture after balloon embolization occurred in five aneurysms; all of which were incompletely occluded by a silicone balloon. On subsequent angiograms, four silicone balloons and one latex balloon were found to have migrated into the aneurysm, resulting in aneurysmal expansion. Parent artery occlusion was more common with latex balloons than silicone balloons. Histopathologically, residual fresh thrombi, decreased proliferation of fibroblasts within the aneurysmal cavity, and poor endothelialization were present around the silicone balloon. These results suggest that the intra-aneurysmal organization, as seen in the aneurysm occluded by the silicone balloon, will be delayed because the balloon is not fixed within the aneurysm, and that this free-floating and rotating balloon causes repeated trauma to the aneurysm wall, contributing to subsequent enlargement and rupture of the aneurysm. The superior antithrombogenic nature of silicone may be responsible for the bias of such phenomena toward the silicone balloon.

The time-dependent changes in the chromatographic pattern of subcutaneously injected cadmium associated with non-metallothionein cadmium-binding proteins were studied in the rat liver cytosol. Prior to the induction of cadmium-thionein (less than 3 h), cadmium appeared in three major peaks (P-1 with the void volume, P-2 and P-3) on Sephacryl S-300 column chromatography. Accompanied with the emergence of apo-metallothionein (about 3 h after administration), the amount of P-3 decreased and instead a cadmium-thionein peak (P-4) increased. Ion-exchange chromatography of P-3 with a combination of CM and DEAE Bio-Gel columns showed the existence of three major cadmium-binding proteins with molecular sizes of 46 kDa (in the CM Bio-Gel column eluate), 50 kDa (in the DEAE Bio-Gel column eluate), and 41 kDa (in the non-adsorbed fraction). The cadmium-binding protein in the CM Bio-Gel column eluate was purified to apparent homogeneity. The purified protein (CM-CdP) was 47 or 53 kDa in molecular size as determined by SDS-polyacrylamide gel electrophoresis or gel filtration chromatography, respectively. The apparent dissociation constant and maximum binding for cadmium were about 1 microM and 1 mol of the metal/mol of protein, respectively. The isoelectric point was estimated to be 8.8. The amino acid composition showed that the protein was relatively rich in glutamyl (including its amide) and alanyl residues. The N-terminal amino acid sequence was determined as Ala-Pro-Ile-Ala-Gly-Lys-Lys-Ala-Lys-Ala-Gly-Ile-Leu-Leu-Gly-. In-vitro experiments revealed that cadmium bound to CM-CdP could be easily transferred to apo-metallothionein, confirming that the affinity for the metal of the former protein was lower than that of the latter.

Vitellin was purified from eggs of the silkworm,Bombyx mori, by a new method in which vitellin was extracted from isolated yolk granules. The purified vitellin had a molecular weight of 540,000. An antibody against purified vitellin was prepared in rabbits. It reacted with the hemolymph vitellogenin as well as with purified vitellin, but not with other proteins in the hemolymph or in the extract from yolk granules. The anti-vitellin IgG was used to immunocytochemically locate vitellin in theBombyx non-diapause egg during early developmental stages. In the egg, just after oviposition, vitellin was located in internal yolk granules and in small yolk granules of the periplasm. During the early developmental stages studied, vitellin was not metabolized uniformly throughout the egg. The vitellin of the internal yolk granules located at the posterior-dorsal part and of the small peripheral yolk granules was utilized in 16 h and 2 days, respectively, after oviposition. A thin, very vitellin-poor layer was located between the periplasm and the vitellin-rich interior in the newly laid egg. it was always in close contact with the periphery where blastoderm and germ-band cells developed.

Postnatal changes in cerebellar wet weight and the effect of phototherapy were studied using a new strain of Gunn rats with a genetic background of the Sprague-Dawley strain (SDGR). The cerebellar wet weight of homozygous rats reached a maximum at postnatal day 10 and then it gradually decreased up to day 20, suggesting that the cerebellar hypoplasia of the rats was a consequence both of cellular underdevelopment and degeneration. Histological examinations of the 10 cerebellar lobules showed that lobules I-VIII of homozygotes were severely damaged while lobules IX and X were less affected, coinciding with previous reports of Wistar strain Gunn rats. Photoirradiation with blue light of homozygous rats from day 1 through 15 markedly improved their cerebellar development, and the cerebellar wet weight of these rats was almost comparable to that of heterozygous rats as examined at day 30. Photoirradiation from day 1 to 5 protected, though not fully, lobules I-V and VIII against damage, but not lobules VI and VII at all. Photoirradiation from day 6 to 10 prevented all the lobules from hypoplasia. Irradiation from day 11 to 15 was effective only at the tips of lobules VI and VII. These results indicate that the cerebellar hypoplasia of jaundiced Gunn rats can be effectively prevented by a series of photoirradiation during a particular period after birth and also that the most effective period is different among the lobules.

The surface change of the egg of the teleost, Oryzias latipes, during fertilization was observed with a scanning electron microscope. The microvilli of the outer surface of the unfertilized egg show a slight difference in density between the animal and vegetal pole areas. In the initial step of the breakdown of cortical alveoli (CA), several small holes or gapes are formed at the apical part of the CA membrane, becoming a large aperture from which the alveolar contents are discharged. The formation of microvilli is observed on the inner surface of the exposed cavity left by the CA, starting from the periphery of the aperture and propagating throughout the whole inner surface in accompaniment with the release of the alveolar contents. After the completion of CA breakdown, the CA membrane cannot be distinguished from the original egg plasma membrane.

Microtubules in the silkworm egg, Bombyx mori, were observed by electron microscopy, in order to investigate the relationship between cytoskeletal organelles and the migration of energids, the cleavage nuclei accompanied by the associated cytoplasm, near the egg surface or during blastoderm formation. Numerous microtubules were observed in the associated cytoplasm of an energid even in the interphase of mitosis. At about 8.5 hr after oviposition, when many energids had already cleft and distributed near the peripheral yolk granule region, long microtubules distributed radially from the perinuclear region to the periphery in the associated cytoplasm. When an energid was protruding, the microtubules above the nucleus distributed at a more acute angle than those under the nucleus. When a blastoderm cell had just been formed, the microtubules were observed only under the nucleus. Colchicine, an inhibitor of microtubules, stopped the migration of energids and inhibited the formation of blastoderm cells even after many energids had already distributed at the peripheral yolk granule region. The relationship between the microtubules and the migration of energids near the egg surface or during blastoderm formation was discussed.

Cerebella from 20-day-old homozygous (jj) and heterozygous (j+) Gunn rats were tested histochemically for the presence of acid phosphatase. The j+ rat cerebellum as well as the jj rat cerebellum with wet weights over 120 mg showed a strong acid phosphatase activity in the pia mater and in endothelial cells. A strong acid phosphatase activity was also recognized in small cells with a diameter of about 8 micrometers and large cells with a diameter of about 25 micrometers in the hypoplastic cerebellum of jj rats. The small cells were present in the lingula, centralis, culmen, declive, tuber, pyramis, and dorsal part of the uvula of the jj rat cerebellum with wet weight below 120 mg. The large cells were observed only in severely damaged lobes. Neither small cells nor large cells were found in the nodulus even in a cerebellum with a high degree of hypoplasia. Slightly damaged cerebella with wet weight of 100 to 150 mg showed hypoplasia mainly in the anterior lobe including the lingula, centralis, and culmen as well as in the declive and tuber, where no small cells were detected.