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Biomedical subjects

C C Liu

Publications and source records attributed to C C Liu.

At least 289 records · Page 16Linked to original sources
PubMed1979

Potentiometric method for substrate analysis using immobilized NAD + -dependent oxidoreductase enzymes.

Two coenzyme-dependent oxidoreductases, glucose dehydrogenase and alcohol dehydrogenase, were immobilized in polyacrylamide gel over a platinum grid matrix and used as enzyme electrodes to measure their substrate concentrations in buffered aqueous solutions. The immobilized enzymes were used to oxidize their substrates in the presence of NAD +. Ferricyanide was used as the redox mediator and electroactive species. The determinations of glucose and ethanol were utilized to demonstrate and evaluate the performance of the system. The described methodology should be readily applicable to the analysis of numerous other substrates of coenzyme-dependent oxidoreductases.

Acrylamides↗
PubMed1979

Immobilized enzyme electrodes for the potentiometric measurement of glucose concentration: immobilization techniques and materials.

Glucose oxidase, catalase, and bovine serum albumin were co-immobilized with glutaraldehyde around a platinum screen or around a single platinum-iridium wire. The potential difference between this dual enzyme electrode and a Ag/AgCL reference electrode was proportional to the logarithm of the glucose concentration over the range from 10 to about 150 mg glucose per 100 ml in buffered solution at pH 7.4 and 37 degrees C. The enzyme electrode responded in serum only if coated with a semipermeable film, such as cellulose acetate, to exclude serum macromolecules. The potentiometric results were similar to those obtained with the two enzymes co-immobilized in polyacrylamide gel around a platinum screen or with only one of the enzymes, glucose oxidase, covalently coupled to a platinum screen. The results so far suggest that glucose for development of a continuous in vivo glucose sensor.

Catalase↗
PubMed1979

Can osteoid osteoma become osteoblastoma? A case report.

A case of osteoid osteoma of the spine that recurred as an osteoblastoma 16 years after surgery is reported. Consequently, the authors suggest that osteoid osteoma and osteoblastoma originate from the same cellular element and are of the same nature. The only differences are their size and the reaction of the bone at the site of the lesion, which gives controversial clinical pictures and roentgenologic appearances, simulating two unrelated tumors.

Adult↗
PubMed1977

Electrochemical evaluation of lactate dehydrogenase immobilized in polyacrylamide gels.

Lactate dehydrogenase (EC 1.1.1.27) has been immobilized in polyacrylamide gels over a platinum grid matrix. The immobilized enzyme is used to oxidize L-lactate in the presence of nicotinamide adenine dinucleotide (NAD+) and ferricyanide. The NADH produced is then chemically oxidized back to NAD+ by ferricyanide. The coupled reduction of ferricyanide ions to ferrocyanide ions results in a measurable electrochemical potential. This measurable zero-current potential is found to be Nernstian in nature and directly proportional to the logarithm values of L-lactate concentration over the range of 2 X 10(-5) to 5 X 10(-2)M. The results indicate that immobilized lactate dehydrogenase can be incorporated into a system to detect L-lactate acid in aqueous solutions.

Acrylamides↗
PubMed1977

Pore size measurements and some age-related changes in human alveolar bone and rat femur.

Bone pore volume of pores ranging from 0.1 to 77 mum in diameter was unchanged in alveolar bone from patients with periodontal disease compared with control subjects, a finding that is inconsistent with the involvement of systemic factors in alveolar bone loss in this disease. Bone density was decreased in alveolar bone from patients with periodontal disease. Bone density of normal alveolar bone increased with age. A similar finding was obtained in rat diaphyseal bone, suggesting that this is a general phenomenon in aging bone. This could be significant inasmuch as high density bone would be expected to be more brittle. In contrast to these findings in normal alveolar bone, bone density decreased rather than increased in the 50- to 59-year-old age group in patients with periodontal disease. The cause of decreased bone density remains to be established.

Adolescent↗
PubMed1977

Stimulation of bone formation and bone resorption by fluoride in thyroparathyroidectomized rats.

In sham-operated and TPTX animals, F treatment did not affect final body weight, or serum Ca and P. In sham-treated rats, serum iPTH was not affected by F treatment. At the periosteum, F increased bone formation rate and bone and matrix apposition rates. At the endosteum, F treatment decreased forming surface, bone formation rate, bone and matrix apposition rates, and osteoid maturation rate; and increased endosteal resorbing surface and medullary area. The above-described F effects on bone were observed in TPTX as well as sham-treated animals. The effect of F treatment to stimulate periosteal matrix apposition was enchanced by TPTX. These results indicate that bone changes seen in animals treated with large amounts of F are not due to increased parathyroid activity.

Animals↗
PubMed1976

Immobilization of tyrosinase within polyacrylamide gels.

The enzyme tyrosinase (E.C. 1.14.18.1)has been immobilized in a polyacrylamide gel and intermittently assayed for enzyme activity over a period of 19 days using phenol as the substrate. The results of these studies indicate that the immobilized enzyme could be incorporated into a system to detect phenol and related compounds that are found in industrial effluents and as surface water contaminants.

Acrylamides↗
PubMed1976

Hyaluronidase-bound membrane as a biomaterial for implantable fuel cells.

A new biomaterial containing covalently bound hyaluronidase was prepared. An application of this enzyme membrane is to improve the performance of an implantable fuel cell. Hyaluronic acid is a contributor to the viscosity of tissue fluids but can be a potential fuel source because of its sugar content. The incorporation of immobilized hyaluronidase would not only contribute to a more available fuel supply by splitting hyaluronic acid but, perhaps more importantly, enhance the rate of mass transport of fuel, O2, and reaction products by reducing the viscosity near the electrode membranes. Hyaluronidase was bound to Sepharose gel and its thermoplastic membrane after activation by cyanogen bromide. Fourteen and 22% of the activities were recovered from the gel and membrane, respectively. The activity of the bound enzyme was stable for six months at 0 degrees C. The addition of hyaluronic acid, 1 mg/ml, to a typical implantable type bioautofuel cell in vitro increased external solution viscosity from 1.1 to 2.5-2.8 cP and reduced voltage output under 10 komega by 60% in 3 hr. When the hyaluronidase bound membrane was placed at the anode, viscosity of the glucose-hyaluronic acid solution was lowered to 1.8 cP and the cell output increased to the original level of a glucose-fueled cell in 3 hr. Glucosamine-equivalent released from hyaluronic acid at the electrode was 3.1 mg after 22.5 hr. This represents 90% of the theoretical consumption. Restoration of the cell output was probably a combination of the enhanced transport of fuel, O2 and products, and/or appearance of a new fuel, glucosamine-equivalent.

Biocompatible Materials↗