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Biomedical subjects

J Yu

Publications and source records attributed to J Yu.

At least 955 records · Page 53Linked to original sources
PubMed1975

Isolation and characterization of band 3, the predominant polypeptide of the human erythrocyte membrane.

Band 3 is the predominant approximately 90,000-dalton polypeptide component of the human erythrocyte membrane. It was solubilized selectively, along with the other major glycoproteins, by extracting membrane ghosts with Triton X-100 under nondenaturing conditions. Two major polypeptides remained associated with Band 3 under these conditions; however one (Band 6) could be dissociated at an ionic strength of 0.15 and the other (Band 4.2) by treatment with p-chloromercuribenzoate. Band 3 was then purified (greater than or equal to 97%) by aminoethyl cellulose ion exchange chromatography. The isolated protein was free of phospholipid and was moderately enriched in apolar amino acid residues; it contained galactose and glucosamine but very little sialic acid and galactosamine. When Band 3 was labeled by treatment of ghosts with galactose oxidase plus KB3H4 and then purified, the electrophoretic mobility of its radioactivity lagged slightly behing that of its Coomassie blue staining profile. Variation in glycosylation could therefore cause the diffuse trailing zone characteristically observed for Band 3 on polyacrylamide gel electrophoresis in sodium dodecyl sulfate. The ultraviolet circular dichroism of Band 3 was stable in nonionic detergent and suggested an alpha helix content of 43%, a value close to that estimated for this polypeptide in the membrane.

Amino Acids↗
PubMed1975

The role of the medial lemniscal and spinocervicothalamic pathways on tactile reactions in cats.

The role of dorsal column (DC)-medial lemniscus and spinocervicothalamic systems on tactile reactions, placing and tactile localization (turning to localize a point touched on the body) was studied in cats with spinal and bulbar lesions. The cats with vision occluded were trained preoperately on horizontal bars for tactile localization. The bulbar lesions of cervicothalamic tract (CTT), which anatomically overlaps with gracile nuclear efferent projection, resulted in permanent loss of tactile placing and localization in contralateral hindlimb. Section of dorsal half of lateral funiculus at C3, which interrupts afferents to lateral cervical nucleus but also involves descending motor pathways, gave loss of tactile placing without impairment of tactile localization. However, combined lesions of both systems abolished tactile placing and localization permanently. Results suggest that tactile placing and localization persists after CTT lesion alone; temporarily loss after DC section but permanently abolished after destruction of both systems. It. is also noted that cats after lesions of both systems without involving motor pathways could walk on bars without vision. The deficits following combined lesions are suggested to be primarily sensory in nature.

Animals↗
PubMed1972

The effects of cerebellar lesions upon skilled movements and instrumental conditioned reflexes.

Eight cats were trained in reaching for food with their forelegs in cylinders 19-21.6 cm long of various diameters (3.9-10.1 cm). When the pre-operative training was completed, in six cats the interposite and dentate intracerebellar nuclei were destroyed, whereas in two cats the paravermal cortex was ablated. Interposite animals displayed big oscillatory movements around the entrance to the cylinder and overshooting in reaching for food with occasional forced grasping. Paravermal cats displayed overflexion leading to missing the entrance of the cylinder and wild batting movements observed in the large cylinder. The physiological mechanism of these disorders is discussed.

Animals↗
PubMed1968

Milk-clotting Enzyme from Microorganisms: V. Purification and Crystallization of Mucor Rennin from Mucor pusillus var. Lindt.

A rennin crystal was obtained from the crude milk-clotting enzyme of Mucor pusillus var. Lindt. The crude enzyme was purified by using columns of Amberlite CG-50, diethylaminoethyl Sephadex A-50, and Sephadex G-100. This purified enzyme was dissolved in 0.1 M sodium acetate (pH 5.0) buffer to a final concentration of 2 to 3%; ammonium sulfate (to 40% saturation) was added, and the resulting solution was placed in cellophane tubes. The enzyme solution was dialyzed against 0.1 M sodium acetate buffer (pH 5) containing ammonium sulfate was added dropwise to the outside solution of the cellophane tube, and the concentration of ammonium sulfate in the cellophane tube increased gradually. The crystals of enzyme were formed in the cellophane tube when the concentration reached approximately 50% saturation. After the enzyme solution was concentrated in the freezer, the crystals were obtained. The activity of the crystalline enzyme was inhibited by Hg, Ag, Zn, and KMnO(4).

Journal Article↗
PubMedDate not supplied

Mediator caused induction of a human bradykinin B1 receptor minigene: participation of c-Jun in the process.

The bradykinin B1 receptor (BKB1R) gene is expressed in selected tissues such as lung and kidney. In these tissues it is expressed at a very low level until induced by inflammatory mediators. Our aim has been to understand the mechanism of this regulatory process. A human BKB1R minigene was constructed. It contained a 1.8 kb promoter, the entire exon I, 1.5 kb of intron I, the entire exon II and intron II, and the luciferase gene as a reporter. Transient transfection of the minigene into SV40-transformed IMR90 cells (IMRSV) resulted in a promoter activity which was activated by the mediators, lipopolysaccharide and (LPS) desArg(10)-kallidin. In contrast, these mediators did not induce the activity of the 1.8 kb promoter construct alone. Thus, motifs exclusive of the promoter such as 5'-UTR and/or intron regions are required for mediator-induced expression of this gene. Promoter activities of both the minigene and the 1.8 kb promoter construct were enhanced in a dose-dependent manner upon cotransfection with c-Jun. Furthermore, cotransfecting c-Jun with the minigene achieved the maximal promoter activity with no further increase in response to mediators. Conversely, the induction of the minigene promoter activity by mediators was abolished upon cotransfection with a dominant negative mutant of c-Jun. Other experiments suggest that multiple AP-1 sites are interactive with the c-Jun upregulation of this gene. Taken together, these results point to c-Jun as a key intermediary in the activation of the expression of this gene by mediators. However, participation of motifs outside of the promoter are necessary to obtain this inducible expression.

Exons↗