Search PubMed⌕ Search

Biomedical subjects

T S Chang

Publications and source records attributed to T S Chang.

At least 127 records · Page 7Linked to original sources
PubMed1975

Bovine serum albumin in lithium chloride solutions.

The effects of li+ and H3O+ on the conformation of bovine serum albumin in azqueous solutions at room temperature are compared. At low pH (high concentration of H3O+) the change in conformation of the protein is demonstrated by an increase in effective volume, a decrease in helical content and a blue shift of tyrosyl residue. A similar change is observed for the protein in highly concentrated LiC1 solution (6.0-7.0M) at neutral pH. However, the H3O+ is 12,000 times more powerful than the Li+ in destabilizing the protein molecule. This is consistent with their thermodynamic and kinetic properties, since the H3O+ is often different from the Li+ in several orders of magnitude. While the changes in structural properties of the protein are almost identical in both the acidic solution and the highly concentrated LiC1 solution, further study using dioxane as a probe suggests different mechanisms under which the changes occur. The effect of H3O+ is related to electrostatic force, whereas the effect of Li+ is related to both the electrostatic hydrophobic forces. These two major forces are believed to be responsible for the conformation of protein molecules.

Chlorides↗
PubMed1970

Determination of untreated whole-milk effects on in vitro antibacterial activity.

The effect of fresh whole milk without pasteurization or other pretreatment on in vitro antibacterial activity of selected compounds was determined in broth dilution. The milk was collected by hand directly from dairy goats, or by syringe or cannula from bovine quarters showing low bacterial counts. Antibacterial activity was determined in 50% (v/v) milk-broth medium against sensitive mastitis-etiologic strains of Streptococcus agalactiae and Staphylococcus aureus. The indicator salt 2,3,5-triphenyltetrazolium chloride was incorporated in the milk broth medium to determine inoculum growth. Contaminant interference was circumvented through early as well as late readings and comparisons with uninoculated control tubes, with and without the test compounds. Application of the method with more than 75 compounds, including nitrofurans, antibiotics, and other chemicals uncovered marked degrees of milk interference. The method warrants routine use among preliminary screens to relate in vitro with in vivo observations of antimicrobial activity. Similar procedures may be used with serum, skim milk, or mastitis-milk media for separating effects due to protein, lipid, or other elements in product evaluation.

Animals↗
PubMedDate not supplied

Experiences in microsurgery in The People's Republic of China.

In 1963, the successful replantation of an upper extremity amputated at the forearm provided the impetus for great interest in this surgical procedure in the People's Republic of China. In the 16 years since that time, much progress has been made, especially after the introduction of microsurgical techniques. Prior to 1973, replantation of digits was performed 443 times under the naked eye, with a digit survival rate of 51%. Since 1973, 92 replantations have been done under the microscope, with a digit survival rate of 91%. Experience is also recorded for free abdominal skin grafts, toe transplants for thumb and finger reconstruction, free dorsalis pedis flaps, free vascularized fibular transplants, free muscle transplants, jejunal transplants for esophageal defects, combined free grafts of the omentum and skin for repair of scalp, cranial, and extremity defects, and extracranial-intracranial blood flow diversion.

China↗
PubMedDate not supplied

Characterization of sulfhydryl proteins involved in the maintenance of flagellar straightness in hamster spermatozoa.

Hamster caput epididymal spermatozoa exhibit a marked 90-180 degree bend when induced to acquire progressive motility in vitro (Cornwall et al, 1988). Flagellar bending is prevented by oxidizing sperm sulfhydryl (SH) groups with diamide. In the present study, the authors examined the SH proteins involved in sperm flagellar bending using two-dimensional polyacrylamide gel electrophoresis and monobromobimane, an SH-specific fluorescent dye. Proteins extracted from samples containing bent caput spermatozoa contained more reduced SH than the same proteins extracted from straight caput spermatozoa. To further characterize these sperm SH proteins, caudal epididymal spermatozoa that exhibited straight flagella were induced to undergo flagellar bending by treatment with the SH reductant dithiothreitol. Specific proteins of 85-94 kDa, 50-55 kDa and 35-40 kDa, which were rich in SH groups when extracted from samples containing bent caput spermatozoa, were also SH-rich in samples containing bent cauda spermatozoa. These studies suggest that oxidation of specific SH proteins may be important for maintaining sperm flagellar morphology.

Animals↗
PubMedDate not supplied

Effect of bursal cell number on the pathogenesis of infectious bursal disease in chickens.

The pathogenesis of infectious bursal disease (IBD) in chickens neonatally chemically bursectomized (CB) by cyclophosphamide and subsequently inoculated with various numbers of bursal cells was examined. CB chickens inoculated with at least 62.5 X 10(6) bursal cells were as susceptible to IBD clinical manifestations (as determined by gross and microscopic evaluation of bursal tissues, virus recovery from spleen, and antibody titer) as intact chickens following inoculation with virus at 5 weeks of age. In contrast, CB chickens inoculated with 2.5 X 10(6) or fewer bursal cells were refractory to the IBD clinical manifestations compared with intact chickens or CB chickens inoculated with 62.5 X 10(6) or more bursal cells. Results from this study suggest that the availability of a large number of bursal cells is an essential factor in the development of IBD.

Animals↗
PubMedDate not supplied

Monoclonal-antibody-mediated enzyme-linked immunosorbent assay for detection of reticuloendotheliosis viruses.

An enzyme-linked immunosorbent assay (ELISA) is described for the detection of reticuloendotheliosis viruses (REVs). The assay uses a mixture of monoclonal antibodies (MCAs) prepared against a 62-kilodalton REV envelope glycoprotein (gp62) to capture antigen, rabbit anti-REV serum as detection antibody, and peroxidase-conjugated anti-rabbit IgG as indicator antibody. The MCAs were reactive with REV strain T, chick syncytial virus, and duck infectious anemia virus but unreactive against Marek's disease and avian leukosis viruses. The ELISA was compared with complement fixation test and REV immunofluorescent assay of infected fibroblasts, plasmas, and egg albumen from infected chickens. The lower limit of gp62 detection was about 120 ng of REV protein. Limit dilution of infectious REV was detected after 7-8 days of cultivation of infected fibroblasts.

Animals↗