Cleavage within Reelin repeat 3 regulates the duration and range of the signaling activity of Reelin protein

Reelin is a secreted glycoprotein that plays essential roles in the brain. Reelin is specifically cleaved at two distinct sites, called N-t and C-t, with the former being the major one. N-t cleavage can occur both in the extracellular space and in the endosomes, although the physiological importance of endosomal N-t cleavage has not been investigated. In this study, we first determined the exact N-t cleavage site catalyzed by a protease secreted by cerebral cortical neurons. Cleavage occurred between Pro-1244 and Ala-1245 within Reelin repeat 3. A Reelin mutant in which Pro-1244 was replaced with aspartate (Reelin-PD) was resistant to a protease secreted by cultured cerebral cortical neurons, and its biological activity stayed active longer than that of wild-type Reelin. Interestingly, Reelin-PD remained in the intracellular compartments longer than wild-type Reelin and persistently activated downstream signaling. Therefore, N-t cleavage of Reelin is required for halting the signaling machinery in the extracellular space as well as within endosomes of target neurons. We established a monoclonal antibody specific to uncleaved Reelin protein and found that it is localized in the vicinity of Reelin-producing cells, whereas the N-terminal fragment diffuses, or is transported, to distant regions. These data demonstrate that N-t cleavage of Reelin plays critical roles in regulating the duration and range of Reelin functions both in the extracellular milieu and in the intracellular compartments.

A disintegrin and metalloproteinase with thrombospondin motifs 4 (ADAMTS-4) cleaves Reelin in an isoform-dependent manner

Reelin is a glycoprotein essential for brain development and functions. Reelin is subject to specific proteolysis at two distinct (N-t and C-t) sites, and these cleavages significantly diminish Reelin activity. The decrease of Reelin activity is detrimental for brain function, but the protease that catalyzes specific cleavage of Reelin remains elusive. Here we found that a disintegrin and metalloproteinase with thrombospondin motifs 4 (ADAMTS-4) cleaves Reelin in an isoform-specific manner. Among ADAMTS-4 isoforms, p50 cleaves the N-t site only, while p75 cleaves both sites. This is the first report identifying a protease that can specifically cleave Reelin.

Effects of adding dietary lysine to a low gluten diet on the brain protein synthesis rate in aged rats

The purpose of this study was to find whether the addition of dietary lysine affected the rate of brain protein synthesis in aged rats fed on a gluten diet. Experiments were done on two groups of aged rats (30 wk) given the diets containing 5% gluten or 5% gluten + 0.3% lysine for 10 d. The fractional rates of protein synthesis in brain, liver, and kidney increased with an addition of dietary lysine. In brain, liver, and kidney, the RNA activity [g protein synthesized/(g RNA x d)] was significantly correlated with the fractional rate of protein synthesis. The RNA concentration (mg RNA/g protein) was not related to the fractional rate of protein synthesis in any organ. The results suggest that the addition of the limiting amino acid for the low quality protein elevates the rate of protein synthesis in the brain of aged rats, and that RNA activity is at least partly related to the fractional rate of brain protein synthesis.

Effect of dietary protein quality on the brain protein synthesis rate in aged rats

The purpose of this study was to determine whether the quality of dietary protein affects the rate of brain protein synthesis in aged rats. Experiments were conducted on three groups of aged rats (30 wk) given diets containing 20 g casein, 20 g gluten or 20 g gelatin/100 g for 10 d. The fractional rates of protein synthesis in the brain, liver and kidney declined with the decrease in quality of dietary protein. In the brain, liver and kidney, the RNA activity [g protein synthesized/(g RNA.d)] correlated significantly with the fractional rate of protein synthesis. The RNA concentration (mg RNA/g protein) was not related to the fractional rate of protein synthesis in any organ. The results suggest that the rate of protein synthesis in the brain declines with the decrease in quality of dietary protein consumed by aged rats, and that RNA activity is at least partly related to the fractional rate of brain protein synthesis.

The quantity of dietary protein affects brain protein synthesis rate in aged rats

The purpose of this study was to determine whether the quantity of dietary protein affects the rate of brain protein synthesis in aged rats. Experiments were conducted on three groups of 30-wk-old rats fed diets containing 0, 5 or 20 g casein/100 g for 10 d. The fractional rates of protein synthesis in brain, liver and kidney declined with a decrease in quantity of dietary protein. In brain, liver and kidney, RNA activity [g protein synthesized/(g RNA.d)] was significantly correlated with the fractional rate of protein synthesis. The RNA concentration (mg RNA/g protein) was not related to the fractional rate of protein synthesis in any organ. The results suggest that the rate of protein synthesis in the brain declines with a decrease in quantity of dietary protein in aged rats, and that RNA activity is at least partly related to the fractional rate of brain protein synthesis.

Role of N-acetylglutamate turnover in urea synthesis by rats treated with the thyroid hormone

We determined whether the synthesis and degradation of N-acetylglutamate would regulate urea synthesis when the thyroid status was manipulated. Experiments were done on three groups of rats, each being given 6-propyl-2-thiouracil (PTU, a thyroid inhibitor) without a triiodothyronine (T3) treatment, treated with PTU + T3, or receiving neither PTU nor T3 (control). The plasma concentration and urinary excretion of urea, the liver concentration of N-acetylglutamate, and the liver N-acetylglutamate synthesis in rats given PTU alone were each significantly higher than in the control rats. Compared with the control rats, the liver N-acetylglutamate degradation was significantly lower in those rats given PTU without the T3 treatment. Treatment of the PTU-treated rats with T3 reversed the effects of PTU to the values of the control rats. N-Acetylglutamate synthesis in the liver was closely correlated with the excretion of urea, and inverse correlation between the liver N-acetylglutamate degradation and urea excretion was found. These results suggest that the greater synthesis and lower degradation of N-acetylglutamate in the hypothyroid (PTU alone) rats would be likely to increase the hepatic concentration of this compound and stimulate urea synthesis.

Osteoinductive activity of composites of bone morphogenetic protein and pure titanium

Titanium sponges were infused with bone morphogenetic protein (BMP-Ti), and the osteoinductivity of the resultant composite was measured. New bone formation occurred three weeks after implantation and was identified by soft x-ray analysis. Quantitative analysis showed no significant difference between BMP-Ti composites and control samples (BMP only). Consequently, pure titanium neither inhibited nor promoted BMP activity. Chondrocytes and new bone formation occurred in direct contact with the surfaces of the titanium. X-ray microanalysis demonstrated new bone formation inside the pores of the titanium sponges. The BMP-Ti composite has interesting properties as an osteoinductive implant and has potential practical clinical applications.

[The treatment of condyle neck fracture: statistics gathered by multi centric study and the related prognosis]

There are two different treatments for condyle neck fracture. One is non-surgical treatment involving intermaxillary fixation, and the other is radical surgical treatment through various techniques, but it is difficult to discuss the relative merits. The purpose of this report is to decide whether surgical treatment is necessary, by comparing the two types of treatment. In the period between April 1981 to December 1987, we treated 136 cases of condyle neck fracture at the Second Department of Oral and Maxillofacial Surgery School of Dentistry Aichigakuin University, and in 18 nearby hospitals. Of the 136 cases, 58 cases had fracture only at the condyle neck, while 78 cases had some concomittant fracture. As regards treatment, of the 136 cases, 49 (36%) were treated surgically, while 87 (64%) were treated non-surgically for condyle neck fracture. The surgically treated cases were divided into three groups: 24 cases were treated by pinning, 16 cases were treated by inter osseous wiring, and there were 9 other cases. In the treatment of concomittant fracture, 38 cases involved inter osseous wiring, 22 cases involved metal plate fixations, and there were 4 other cases. Non-surgical treatment accounted for 15 cases. The rate of surgical treatment for concomittant fracture was 82.1% of the cases treated. In surgically treated cases of condyle neck fracture, the mouth opening prognosis was generally poor. However, in these cases the deviation of mouth opening was generally better than in non-surgically treated cases. There were no differences in mastication, occlusion and pain in the TMJ region.

[Bone inductive activity of hydroxyapatite-bone morphogenetic protein complex]

Bone morphogenetic protein (BMP) is known to be a protein which induces new bone at heterotopic sites. Purification of BMP has not been perfected, and obtaining large amounts of BMP is very difficult, so it seems better to use some carrier or frame material for BMP to work effectively. Various kinds of hydroxyapatite (HAP) have been used to repair periodontal osseous defects, but they do not have osteogenetic or osteoinductive properties. If osteoinductive proteins such as BMP could retain their biologic properties after being implanted into living tissue with HAP, it would be an advantage in repairing periodontal osseous defects. In this experiment, we prepared BMP-HAP complex and investigated its osteoinductive activity. BMP was extracted from bovine cortical bones in accordance with the Urist's procedure. The ability of this BMP to stimulate new bone growth was ensured by implantation in the muscle pouch of mice. HAP was synthesized by the wet method. The BMP-HAP complex was implanted in the muscle pouch of mice, and osteoinduction was examined 3, 7, 14, and 21 days after implantation to assess its osteo-inductive ability. New bone formation was studied by roentgenographic and histologic observation. In the BMP-HAP group, new bone formation was seen on the roentgenograms and new cartilage and bone were observed histologically in the tissue surrounding the apatite. In the HAP group, no new cartilage or bone formation was noted.

Pearsonellum-Corventum, Gen-Nov Et Sp-Nov (Digenea, Sanguinicolidae), in Serranid Fishes From the Capricornia Section of the Great-Barrier-Reef

Pearsonellum corventum, gen. et sp. nov., is described from the heart of Plectropomus leopardus (type host), Epinephelus quoyanus, E. merra, and E. ongus from the vicinity of Heron I. in the Great Barrier Reef. It has body spines in ventrolateral transverse rows, an X-shaped intestine with long posterior caeca, a single testis, a unique auxillary external seminal vesicle, a well-developed cirrus sac, a post-testicular ovary, a partly preovarian uterus, and a well-developed metraterm. Those characteristics support a closer relationship among many piscine blood fluke genera than indicated by the seven subfamilies recognised in Yamaguti's 'Synopsis of Digenetic Trematodes of Vertebrates'.

Stereoscan studies of cercariae, metacercariae, and adults of Cryptocotyle lingua (Creplin 1825) Fischoeder 1903 (Trematoda: Heterophyidae)

The cercaria of Cryptocotyle lingua has simple pointed spines all over the body. Four pointed modified spines occur dorsally in the mouth, and similar spines surround the openings of the penetration glands. The modified spines are shed shortly after penetration and encystment in the fish host. Less than a week after encystment, cytoplasmic folds develop all over the tegument. After about 4 weeks the cytoplasmic folds have disappeared and the spines are now flattened and serrated. The external surface of adults from herring gulls is very similar to that of mature metacercariae. It is provided with scalelike serrated spines which are especially well developed ventrally on the anterior end.

Stereoscan studies of eggs, free-swimming and penetrating miracidia and early sporocysts of Fasciola hepatica

The egg of Fasciola hepatica has a smooth surface with a slightly elevated circle marking the fracture of the operculum. The operculum and the aperture have crenated edges. The epithelial cells of the miracidium are covered with long cilia. When miracidia are vibrated in an ultrasonic cleaner the cilia of the epithelial cells of the four posteroir tiers are broken off only leaving longitudinal rows of cilium stubs, whereas the cilia of the first tier are still retained. The apical papilla is provided with a dorso-ventral furrow, multiciliated pits and isolated sensory cilia. The narrow intercellular ridge is smooth, whereas the epithelial cells have small cytoplasmic knobs between the cilia. The penetration into the snail (Lymnaea truncatula) and the transforamtion into sporocyst may be separated into three phases. (1) Less than 1 min after attachment to the snail the ciliated cells of the anterior tier are shed and swim away. (2) The cilia of the remaining cells beat violently and after about 5 min most cilia are broken off near the cell surface. The miracidium remains for about 15 min embedded as far as the intracellular ridge receptors (lateral papillae and sheathed ciliated nerve endings). During this period extensive contraction and relaxation of the body are performed. (3) The final penetration of the snail epithelium takes about 15 min. Simultaneously with the penetration into the snail tissue the "bald" cells (epithelial cells with cilium stubs only) of the four posterior tiers loosen, florm globules and fall off. The surface below the cells is smooth and in cytoplasmic continuity with the intercellular ridge and the apical papilla, and this syncytium forms the later tegument of the sporocyst. After a few days the tegument of the sporocyst is provided with microvillus-like projections and the apical papilla and sensory structures are lost.

Stereoscan observations of the miracidium and early sporocyst of Schistosoma mansoni

Whole miracidia of Schistosoma mansoni, miracidia vibrated in an ultrasonic cleaner, and the miracidium-sporocyst transition were studied in the stereoscan electron microscope. After vibrating, the cilia broke off near the bases and the epidermal cells, intercellular ridge and sensory structures were revealed. The apical papilla had a folded surface with penetrating sensory cilia. The number of epidermal cells varied between 17 and 22. The lateral papillae appeared as bulbous projections on either side between the first and second tiers of epidermal cells. There was a ciliated pit nerve ending close to each lateral papilla. A few ciliated pits were found between the cells in the first tier, and up to twelve ciliated pits with long cilia could be found between the second and third tiers. Miracidia placed in haemolymph from Planorbarius corneus cast off the apical ciliated part of the epithelial cells, and large scars appeared where the ciliated plates had been. Later, the syncytial intercellular ridge dispersed throughout the surface of the mother sporocyst, and small cytoplasmic knobs appeared on the surface. The apical papilla and the lateral papillae were still observed a few hours after shedding the ciliated plates, but the ciliated pits disappeared shortly after the ciliated plates were lost.