Uneven distribution of enzymatic alterations on the liver cell surface in experimental extrahepatic cholestasis of rat.

The effect of bile duct ligation on enzyme activities in the subfractions of the rat liver plasma membrane was investigated. Two subfractions were isolated from the rat liver plasma membrane by homogenization and subsequent centrifugation in a discontinuous sucrose gradient. The light subfraction contained fragments of the bile canalicular surface and the heavy fraction contained fragments of the sinusoidal and lateral surfaces of the hepatocyte. Bile duct ligation decreased NaK ATPase and Mg-ATPase activity in the light subfraction, whereas it had no significant effect on these enzyme activities in the heavy fraction. Leucyl-β-naphthylamidase activity was reduced and alkaline phosphatase activity was increased in both subfractions. These facts suggested that ligation of the bile duct led to loss of the secretory polarity of the liver cell. The in vitro effects of some bile acids on the membranebound enzymes in the light subfraction were investigated, and a possible involvement of chenodeoxycholic acid in the alteration of enzyme activities in the bile canalicular membrane was suggested.     

Positional cloning of the gene(WFS1) for Wolfram syndrome

Wolfram syndrome(DIDMOAD syndrome) is an autosomal recessive neurodegenerative disorder characterized by juvenile-onset, insulin-requiring diabetes mellitus and optic atrophy. Other symptoms including diabetes insipidus, neurosensory deafness, urinary tract and neurological abnormalities are often accompanied. In patients, beta-cells are selectively lost from their pancreatic islets of Langerhans. The gene was previously mapped to 4p16.1. By haplotype analysis and recombination mapping in 5 families, we localized the gene within a region less than 250 kb on chromosome 6p. In the region, we identified a novel gene(WFS1) encoding a putative transmembrane protein. Mutations were identified in all affected members of the families and these mutations were associated with disease phenotype. This finding was further confirmed by other investigators and to date, more than 50 mutations were identified in the WFS1 gene from the patients with Wolfram syndrome. The WFS1 gene encodes a protein of 100.3 kDa with 9 to 10 putative transmembrane domains. The protein appears to be important in the survival and maintenance of normal pancreatic beta-cells and neurons. Physiological function of the WFS1 protein and mechanisms by which defective WFS1 lead to the development of Wolfram syndrome need to be clarified.     

Identification of neural genes using Xenopus DNA microarrays.

To isolate novel genes regulating neural induction, we used a DNA microarray approach. As neural induction is thought to occur by means of the inhibition of bone morphogenetic protein (BMP) signaling, BMP signaling was inhibited in ectodermal cells by overexpression of a dominant-negative receptor. RNAs were isolated from control animal cap explants and from dominant-negative BMP receptor expressing animal caps and subjected to a microarray experiment using newly generated high-density Xenopus DNA microarray chips representing over 17,000 unigenes. We have identified 77 genes that are induced in animal caps after inhibition of BMP signaling, and all of these genes were subjected to whole-mount in situ hybridization analysis. Thirty-two genes showed specific expression in neural tissues. Of the 32, 14 genes have never been linked to neural induction. Two genes that are highly induced by BMP inhibition are inhibitors of Wnt signaling, suggesting that a key step in neural induction is to produce Wnt antagonists to promote anterior neural plate development. Our current analysis also proves that a microarray approach is useful in identifying novel candidate factors involved in neural induction and patterning.     

The effect of calcium ion concentration on osteoblast viability, proliferation and differentiation in monolayer and 3D culture

Our research group aims to develop an osteochondral composite using type II collagen gel with hydroxyapatite (HAp) deposited on one side. Soaking gels in Ca2+ and phosphate solution is indispensable to HAp deposition, so relationships between cell behavior and Ca2+ concentration were examined in two- and three-dimensional cultures. The present results indicate that 2-4 mM Ca2+ is suitable for proliferation and survival of osteoblasts, whereas slightly higher concentrations (6-8 mM) favor osteoblast differentiation and matrix mineralization in both 2- and 3-dimensional cultures. Higher concentrations (>10 mM) are cytotoxic. Purely from the perspective of calcium deposition, higher concentrations lead to increased accumulation of Ca2+. Culturing cells in phosphate-containing gel in media with Ca2+ also leads to time-dependent formation of HAp in the gel. Considering the viability of embedded cells, culturing scaffolds in media with Ca2+ concentrations around 5mM is useful for both HAp deposition and osteoblast behavior.     

Immunoglobulin superfamily molecules in the nervous system.

Among the various types of membrane molecules involved in cell-cell interactions in the nervous system, we have focused in this review upon membrane proteins belonging to the immunoglobulin superfamily (IgSF). IgSF molecules are distinctive in that: (1) a large percentage of known neural adhesion molecules belongs to the IgSF; (2) they are homologous in structure (Ig domain), yet exhibit large variation of function in cell-cell interactions. The structure of IgSF molecules is briefly summarized in Section II, and each member of the IgSF which has been found in the nervous system is reviewed in Section III. In Section IV, we have discussed possible properties of yet-unknown nervous system IgSF molecules, on the assumption that nervous system IgSF molecules thus far discovered comprise only a small portion of those existing. Discussion is based upon an analogy with the immune system and upon knowledge of cell-cell interactions in the development of the nervous system. Our principal aims in this review are to summarize knowledge of neural IgSF molecules and to discuss the possibility that some IgSF molecules may encode in their structures instructions for recognizing, or for being recognized by, target neural cells. Further growth of knowledge of IgSF molecules may yield insights into the patterns of cell-cell interactions underlying the formation of neuronal circuits during development.     

Effects of body and head positions on bilateral difference in tympanic temperatures

Summary We have examined the nonparallel changes in tampanic membrane temperatures (T _ty) from the two ears in response to various changes in body and head positions. Upon assuming a lateral recumbent position, the T _ty on the lower side increased while that on the upper side decreased. Pressure application over a wide area of the lateral chest only caused inconsistent and obscure asymmetric changes in T _ty. A lateral flexion of the head with the subject sitting upright and a rotation of the head to the side in a supine position induced an increase in the T _ty on the lower side compared to that on the upper side. The temperature and blood flow of the forehead often decreased on the lower side and increased on the upper side, although such responses were not always concomitant with the asymmetric changes in T _ty. A dorsal flexion of the head with the subject in a reclining position caused a slight increase in the T _ty, whereas raising the head upright induced a slight decrease in them. Two additional experiments were carried out with single photon emission computed tomography using ^99mTc-hexamethylpropyleneamine oxime as tracer, and a slight, relative decrease in counts was noted in the right hemisphere during rotation of the head to the right. These results would strongly suggest that unilateral increases and decreases in T _ty could have been caused by one-sided decreases and increases, respectively, in blood flow to the brain and/or the tympanic membrane, induced by a vasomotor reflex involving vestibular stimulation.     

Creation and use of a composite polyurethane-expanded polytetrafluoroethylene graft for hemodialysis access

The Thoratec (Vectra) polyurethane vascular access graft (TPVA) is among the most recent additions to the list of materials used to construct prosthetic grafts for vascular access during hemodialysis. We give the TPVA very high marks, and recognize the utility of such a graft for use in hemodialysis. However, the strong elasticity of this graft can lead to unexpected complications after suturing. We devised a new surgical method using a TPVA-ePTFE (expanded polytetrafluoroethylene) composite graft, substituting the anastomosis section of the TPVA with a portion of ePTFE graft material, and have been able to overcome most of the TPVA's potential problems. We herein describe the technique.     

Different corticostriatal projections from two parts of the cortical masticatory area in the rabbit

The cortical masticatory area (CMA) elicits rhythmic jaw movements in response to repetitive stimulation and is involved in the control of mastication. Based on jaw movement patterns, the CMA is divided into two parts. One is the part of the CMA in which a T-pattern similar to jaw movements during food transport in natural mastication is evoked by electrical stimulation. The other is more dorsomedially located, and during chewing a C-pattern similar to jaw movements can be induced. However, it is still not known which region of the putamen receives projections from the CMA and whether projections originate from both parts of the CMA. In this study, electrophysiological and histological experiments were undertaken in rabbits to investigate projections from the CMA to the putamen. Both experiments showed that the ventral region of the putamen received projections from the CMA. The density of the projections from the CMA area inducing the T-pattern seemed to be higher than that from the area inducing the C-pattern. Furthermore, the peak latency of the evoked potentials from stimulation of the CMA area inducing the T-pattern was shorter than that from stimulation of the area inducing the C-pattern. The data obtained from the present study indicate the functional role of the ventral region of the putamen in the regulation of mastication, and further suggest that the corticostriatal pathway is involved in the transition between behavioral jaw movement patterns.