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Biomedical subjects

Z Rao

Publications and source records attributed to Z Rao.

27 records · Page 2Linked to original sources
PubMed1998

Distribution of SPR-like immunoreactivity in the medullary visceral zone of the rat and changes following acute myocardial ischemia induced by intravenous injection of vasopressin.

Substance P receptor-like immunoreactive (SPR-LI) structures and changes following intravenous injection of vasopressin in the medullary visceral zone (MVZ) of the rat were studied by using immunohistochemical methods. In normal control rats the distribution of SPR-LI structure in MVZ generally matched with that of immunostaining against substance P (SP-LI) except in some areas. SPR-LI neurons and dendrites differed in size and shape in different areas of MVZ. Their dendrites could be classified into three types, i.e, wool-shaped, smooth and varicose. Some SPR-LI neurons were also positive for tyrosine hydroxylase-like immunoreactivity (TH-LI) . After administration of vasopressin SPR-LI structures became denser, especially at levels of pyramidal decussation (PYX) and area postrema (AP). The dendrites of motor dorsal nucleus of X (NMDX) in the dorsal part of MVZ appeared thin and straight in morphology instead of curl and thick outlooks. These results implicate that some SPR-LI neurons might be involved in the modulation of the cardiovascular stress induced by vasopressin.

Acute Disease↗
PubMed1998

A biomechanical analysis of unilateral hooked-sulcated external fixator on osteomined tibia.

Four tibiae removed from 30-40 years males, who died of accidents in less than 12 hours, were osteomized at medium part. Then these tibiae were fixed by an unilateral hooked-sulcated external fixator (UHSEF), and the bone-fixator system was used as a model of external fixation of tibial fracture. The axial compression, distraction, torsion, antero-posterior and lateral bending rigidity and the strain of the pins were determined in this system. Based on the results, we found that compared with the configuration of four paralleled pins, the rigidity of the fan-like configuration didn't decrease significantly if the angle between lateral and medium pins was less than 45 degrees. But the reverse was true when the frame separation increased from 5 to 8 cm. What' more, the pin strain decreased if the rigidity of the system was improved. These data provided a theoretical basis of biomechanics for the improvement of UHSEF.

Adult↗
PubMed1998

[Cloning and sequencing of the Chinese bovine prion protein (PrPC) gene].

The total DNA was isolated from lymphocyte of peripheral blood of Chinese cattle. The PrPC gene was amplified by polymerase chain reaction, using two primers. It was then cloned into pGEM-T Easy Vector. The result of DNA sequencing was indicated that the 795 bp amplified fragment contains the entire PrPC coding sequence, which has no intron and is same as the published gene sequence.

Amino Acid Sequence↗
PubMed1997

Specific interactions between human integrin alpha v beta 3 and chimeric hepatitis B virus core particles bearing the receptor-binding epitope of foot-and-mouth disease virus.

Purified integrin alpha v beta 3 was used in solid-phase binding studies with chimeric hepatitis B cores which carry the RGD-containing loop of VP1 protein of the foot-and-mouth disease virus (FMDV). High levels of specific binding between the integrin and the particles were detected by enzyme-linked immunosorbent assays. The binding was Mn2+ cation dependent and could be competed with fibronectin, vitronectin, and the peptide GRGDSPK. Particles in which the RGD motif had been mutated to RGE failed to bind, indicating that the chimeric cores bound specifically to the ligand binding site of integrin alpha v beta 3. Electron micrographs showed several individual alpha v beta 3 molecules bound to the surface of each chimeric particle. Collectively, these data constitute firm evidence that the RGD-containing loop of FMDV is critical for binding to alpha v beta 3 and provide support for identification of alpha v beta 3 as a potential cellular receptor for FMDV.

Antigens, Viral↗
PubMed1995

Crystal structure of SIV matrix antigen and implications for virus assembly.

Simian immunodeficiency virus (SIV) is closely related to human immunodeficiency virus (HIV), their matrix antigens (MAs) sharing some 50% sequence identity. MA is a component of Pr55Gag, the sole protein required for assembly of the virion shell. MA targets Pr55 to the plasma membrane, and facilitates incorporation of the virus envelope protein and assembly of the Pr55Gag shell. Cleavage of Pr55 by the viral protease produces the mature protein of relative molecular mass 17-18K, which underlies the host-derived membrane and is important in both virus entry and nuclear localization of the virion core. Here we report the crystal structure of SIV MA. The molecule forms a trimer consistent with oligomerization in vitro, the observed virion architecture, and various biological properties of MA.

Amino Acid Sequence↗
PubMed1995

The structure of a Ca(2+)-binding epidermal growth factor-like domain: its role in protein-protein interactions.

Various diverse extracellular proteins possess Ca(2+)-binding epidermal growth factor (EGF)-like domains, the function of which remains uncertain. We have determined, at high resolution (1.5 A), the crystal structure of such a domain, from human clotting factor IX, as a complex with Ca2+. The Ca2+ ligands form a classic pentagonal bipyramid with six ligands contributed by one polypeptide chain and the seventh supplied by a neighboring EGF-like domain. The crystal structure identifies the role of Ca2+ in maintaining the conformation of the N-terminal region of the domain, but more importantly demonstrates that Ca2+ can directly mediate protein-protein contacts. The observed crystal packing of the domains provides a plausible model for the association of multiple tandemly linked EGF-like domains in proteins such as fibrillin-1, Notch, and protein S. This model is consistent with the known functional data and suggests a general biological role for these domains.

Amino Acid Sequence↗
PubMed1995

Crystallization of a calcium-binding EGF-like domain.

Crystals of a calcium-binding epidermal growth factor (EGF)-like domain of human clotting factor IX suitable for X-ray diffraction analysis have been obtained by vapour diffusion (sitting drop) against 48% PEG 400. The crystals belong to the tetragonal space group P4(3)2(1)2, with unit-cell dimensions a = b = 40.3, c = 98.2 A. The crystals diffract beyond 1.5 A resolution and are relatively stable in the X-ray beam. This is the first reported crystallization of a calcium-binding EGF-like domain.

Journal Article↗
PubMed1995

The calcium binding properties and molecular organization of epidermal growth factor-like domains in human fibrillin-1.

Human fibrillin-1 is a 350-kDa glycoprotein found in 10-nm connective tissue microfibrils. Mutations in the gene encoding this protein cause the Marfan syndrome, a disease characterized by cardiovascular, ocular, and skeletal abnormalities. Fibrillin-1 has a modular structure that includes 47 epidermal growth factor-like (EGF-like) domains, 43 of which contain a consensus sequence associated with calcium binding. A mutation causing an Asn-2144 --> Ser amino acid change in one of the potential calcium binding residues has been described in a patient with the Marfan syndrome. We have chemically synthesized a wild-type EGF-like domain (residues 2126-2165 of human fibrillin-1) and a mutant EGF-like domain containing the Asn-2144 --> Ser amino acid change and measured calcium binding to each using 1H-NMR spectroscopy. The wild-type domain binds calcium with a similar affinity to isolated EGF-like domains from coagulation factors IX and X; however, the mutant domain exhibits > 5-fold reduction in affinity. Rotary shadowing of fibrillin-containing microfibrils, isolated from dermal fibroblast cultures obtained from the Marfan patient, shows that the mutation does not prevent assembly of fibrillin into microfibrils but does alter the appearance of the interbead region. We have modeled a region of fibrillin-1 (residues 2126-2331) encompassing five calcium binding EGF-like domains, using data derived from the recently determined crystal structure of a calcium binding EGF-like domain from human factor IX. Our model suggests that these fibrillin-1 EGF-like domains adopt a helical arrangement stabilized by calcium and that defective calcium binding to a single EGF-like domain results in distortion of the helix. We propose a mechanism for the interaction of contiguous arrays of calcium binding EGF-like domains within the microfibril.

Amino Acid Sequence↗