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Biomedical subjects

B Chang

Publications and source records attributed to B Chang.

191 records · Page 11Linked to original sources
PubMed1977

Clinical significance of 99mtechnetium sulfur colloid accumulation in renal transplant patients.

The accumulation of 99mtechnetium sulfur colloid (99mTcSC) was evaluated in 47 studies performed on 19 renal transplant patients by comparing its transplant activity to its bone marrow accumulation. There was a diagnosis of rejection of 21 of 22 studies (96.5%) in which marked transplant accumulation was noted. In 11 studies of patients with a clinical diagnosis of post-transplant acute tubular necrosis (ATN), the transplant activity varied from none to moderate. Rejection developed in 5 of 6 studies with minimal to moderate accumulation. Normally functioning renal transplant patients, or those with ATN and no superimposed rejection, do not show evidence of 99mTcSC accumulation.

Adolescent↗
PubMed1976

Hormonal stimulation of alpha-amylase synthesis in porcine pancreatic minces.

Minces of porcine pancreas maintained a linear rate or protein synthesis for more than 4 h with similar kinetics in the presence of absence of hormones. alpha-Amylase protein, quantitated by using glycogen percipitation, SDS polyacrylamide gel analysis, and radioimmunoassay, was found to represent 6-7% of the total protein content of the minces. The addition of prostaglandin E1 (10-7M), or a pancreozymin preparation (3-10 Crick-Harper-Raper units/ml) to the incubation media produced within 60 min an increase in alpha-amylase protein above that stored in the tissue 10- to 20-fold greater than that observed in control minces. The addiction of cAMP analogs (10(-3)M) to the medium produced a more variable stimulation of alpha-amylase content. Quantitation of the incorporation of radiolabeled amino acid into alpha-amylase protein with simultaneous determination of the specific activity of the precursor pool suggested that these agents produced at least 3- to 5-fold stimulation of de novo alpha-amylase synthesis. This stimulation was not the result of decreased rates of alpha-amylase catabolism. The addition of actinomycin D (20 mug/ml), a concentration inhibiting more than 93% of new RNA synthesis, failed to alter the stimulation of alpha-amylase synthesis by these agents. Apparent hormonal stimulation of non-alpha-amylase protein synthesis was also observed.

Amylases↗
PubMedDate not supplied

Mouse models of ocular diseases.

The Jackson Laboratory, having the world's largest collection of mouse mutant stocks and genetically diverse inbred strains, is an ideal place to discover genetically determined eye variations and disorders. In this paper, we list and describe mouse models for ocular research available from Mouse Eye Mutant Resource at The Jackson Laboratory. While screening mouse strains and stocks at The Jackson Laboratory (TJL) for genetic mouse models of human ocular disorders, we have identified numerous spontaneous or naturally occurring mutants. We characterized these mutants using serial indirect ophthalmoscopy, fundus photography, electroretinography (ERG) and histology, and performed genetic analysis including linkage studies and gene identification. Utilizing ophthalmoscopy, electroretinography, and histology, to date we have discovered 109 new disorders affecting all aspects of the eye including the lid, cornea, iris, lens, and retina, resulting in corneal disorders, glaucoma, cataracts, and retinal degenerations. The number of known serious or disabling eye diseases in humans is large and affects millions of people each year. Yet research on these diseases frequently is limited by the obvious restrictions on studying pathophysiologic processes in the human eye. Likewise, many human ocular diseases are genetic in origin, but appropriate families often are not readily available for genetic studies. Mouse models of inherited ocular disease provide powerful tools for rapid genetic analysis, characterization, and gene identification. Because of the great similarity among mammalian genomes, these findings in mice have direct relevance to the homologous human conditions.

Animals↗
PubMedDate not supplied

The evolution of acetyl-CoA synthase.

Acetyl-coenzyme A synthases (ACS) are Ni-Fe-S containing enzymes found in archaea and bacteria. They are divisible into 4 classes. Class I ACS's catalyze the synthesis of acetyl-CoA from CO2 + 2e-, CoA, and a methyl group, and contain 5 types of subunits (alpha, beta, gamma, delta, and epsilon). Class II enzymes catalyze essentially the reverse reaction and have similar subunit composition. Class III ACS's catalyze the same reaction as Class I enzymes, but use pyruvate as a source of CO2 and 2e-, and are composed of 2 autonomous proteins, an alpha 2 beta 2 tetramer and a gamma delta heterodimer. Class IV enzymes catabolize CO to CO2 and are alpha-subunit monomers. Phylogenetic analyses were performed on all five subunits. ACS alpha sequences divided into 2 major groups, including Class I/II sequences and Class III/IV-like sequences. Conserved residues that may function as ligands to the B- and C-clusters were identified. Other residues exclusively conserved in Class I/II sequences may be ligands to additional metal centers in Class I and II enzymes. ACS beta sequences also separated into two groups, but they were less divergent than the alpha's, and the separation was not as distinct. Class III-like beta sequences contained approximately 300 residues at their N-termini absent in Class I/II sequences. Conserved residues identified in beta sequences may function as ligands to active site residues used for acetyl-CoA synthesis. ACS gamma-sequences separated into 3 groups (Classes I, II, and III), while delta-sequences separated into 2 groups (Class I/II and III). These groups are less divergent than those of alpha sequences. ACS epsilon-sequence topology showed greater divergence and less consistency vis-à-vis the other subunits, possibly reflecting reduced evolutionary constraints due to the absence of metal centers. The alpha subunit phylogeny may best reflect the functional diversity of ACS enzymes. Scenarios of how ACS and ACS-containing organisms may have evolved are discussed.

Acetate-CoA Ligase↗
PubMedDate not supplied

Indocyanine green videoangiography: current status.

Indocyanine-green (ICG) angiography has experienced a rejuvenated interest in the past few years because of improvements in technological systems. After three years of experience with evolving digital technology, we have reviewed our experience to provide an update on potential applications in a variety of choroidopathies. Based on 3,000 cases studied with ICG angiography, we evaluated the diagnostic value of the procedure in choroidal abnormalities including ischemic, tumor, idiopathic, inflammatory, and neovascularized diseases. ICG angiography is still of limited clinical value in ischemic diseases because of a relatively poor imaging potential for the choriocapillaris. The procedure has not yet provided information which is of significant value in the evaluation and management of choroidal tumors. Valuable information has been provided on the fundamental pathogenesis of certain idiopathic diseases. Preliminary experience in inflammatory diseases is very promising. A genuine advance in imaging of "occult"-choroidal neovascularization has been provided by the diagnostic technique. Improved delineation of these vessels offers opportunities for ICG-guided laser treatment.

Choroid Diseases↗