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Biomedical subjects

T N Liu

Publications and source records attributed to T N Liu.

9 recordsLinked to original sources
PubMed1995

Relative risk of deterioration after mild closed head injury.

In this prospective study, a series of 1812 consecutive mild head injured adult patients who visited the hospital emergency department were assessed. Twenty-eight patients (1.5%) deteriorated after head injury; 23 of these (1.3% of the series) required surgical intervention. Five patients (0.3%) deteriorated due to non-surgical causes [post-traumatic seizure 2, syndrome of inappropriate secretion of antidiuretic hormone (SIADH) 3]. Most of the deterioration occurred within the first 24 hours (57%). Post-traumatic headache was found in 280 patients (15.5%) and 84 patients (4.6%) suffered post-traumatic vomiting. The relative risk is calculated. Age over 60, presence of drowsiness, focal motor weakness, post-traumatic headache and vomiting has increased risk of deterioration (p < 0.001). This study suggests that post-traumatic headache and vomiting deserve more clinical attention rather than being considered as post-traumatic syndrome only.

Adolescent↗
PubMed1989

[Studies on plasma catecholamine and myocardial adrenergic receptors in two strains of rats with different susceptibilities to chronic hypoxia].

Hilltop SD (HT) rats are known to have a high susceptibility to chronic hypoxia, resulting in severe pulmonary hypertension with stronger myocardial contractility as compared to Wistar (W) rats. In our experiments, both HT and W rats were observed at sea level and in a hypobaric chamber simulating an altitude of 5000 m above sea level for 15 days, and plasma catecholamine and myocardial adrenergic receptor levels were determined. The results suggest that the high susceptibility of HT rats is not directly related to the heart itself, while the reactivity of pulmonary vessels needs further investigation.

Altitude↗
PubMed1987

Isolation and characterization of a novel nonheme chloroperoxidase.

Chloroperoxidase, purified from the fermentation of Curvularia inaequalis, had a molecular weight of approximately 240,000 and was composed of 4 subunits of identical molecular weight (Mr 66,000). The enzyme was specific for I-, Br- and Cl-, and inactive toward F-. The optimum pH of the enzyme was centered around 5.0. X-ray fluorescence revealed that the enzyme contained 2.2 atoms of zinc and 0.7 atom of Fe per molecule of protein. The enzyme had no heme-like compound as a prosthetic group, making it the first nonheme chloroperoxidase to be reported. Under oxidative conditions that rapidly inactivated other haloperoxidases, this enzyme was remarkably stable.

Chloride Peroxidase↗
PubMed1985

Purification and properties of ferredoxinTOL. A component of toluene dioxygenase from Pseudomonas putida F1.

Toluene dioxygenase oxidizes toluene to (+)-cis-1(S),2(R)-dihydroxy-3-methylcyclohexa-3,5-diene. This reaction is catalyzed by a multienzyme system that is induced in cells of Pseudomonas putida F1 during growth on toluene. One of the components of toluene dioxygenase has been purified to homogeneity and shown to be an iron-sulfur protein that has been designated ferredoxinTOL. The molecular weight of ferredoxinTOL was calculated to be 15,300, and the purified protein was shown to contain 2 g of atoms each of iron- and acid-labile sulfur which appear to be organized as a single [2Fe-2S]cluster. Solutions of ferredoxinTOL were brown in color and showed absorption maxima at 277, 327, and 460 nm. A shoulder in the spectrum of the oxidized protein was discernible at 575 nm. Reduction with sodium dithionite or NADH and ferredoxinTOL reductase resulted in a decrease in visible absorbance at 460 and 575 nm, with a concomitant shift in absorption maxima to 382 and 438 nm. The redox potential of ferredoxinTOL was estimated to be -109 mV. In the oxidized state, the protein is diamagnetic. However, upon reduction it exhibited prominent electron paramagnetic resonance signals with anisotropy in g values (gx = 1.81, gy = 1.86, and gz = 2.01). Anaerobic reductive titrations revealed that ferredoxinTOL is a one-electron carrier that accepts electrons from NADH in a reaction that is mediated by a flavoprotein (ferredoxinTOL reductase). The latter is the first component in the toluene dioxygenase system. Reduced ferredoxinTOL can transfer electrons to cytochrome c or to a terminal iron-sulfur dioxygenase (ISP-TOL) which catalyzes the incorporation of molecular oxygen into toluene and related aromatic substrates.

Amino Acids↗
PubMed1981

Purification and properties of NADH-ferredoxinTOL reductase. A component of toluene dioxygenase from Pseudomonas putida.

Cells of Pseudomonas putida, after growth with toluene, contain a multicomponent enzyme system that oxidizes toluene to (+)-1(S),2(R)-dihydroxy-3-methyl-cyclohexa-3,5-diene. One of these components has been purified to homogeneity and shown to be a flavoprotein that contains FAD as the only detectable prosthetic group. Fad was removed from the enzyme during purification. However, equilibrium dialysis experiments showed that the enzyme can bind one mol of FAD/mol of enzyme protein. The apparent molecular weight of the enzyme is 46,000, as judged by gel filtration and polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate and mercaptoethanol. The latter result suggests the presence of a single polypeptide chain. The amino acid composition of the enzyme reveals a relatively high content of the hydrophobic amino acids leucine, isoleucine, and valine and is remarkably similar in composition to the flavoproteins that function in certain monooxygenase enzyme systems. The purified enzyme catalyzes the reduction of dichloroindophenol, nitrobluetetrazolium, ferricyanide, and ferredoxinTOL. Its ability to reduce cytochrome c and to function in the toluene dioxygenase enzyme system is absolutely dependent on the presence of ferredoxinTOL.

Amino Acids↗
PubMed1977

"Active" one-carbon generation in Saccharomyces cerevisiae.

A new mutation introducing a one-carbon requirement (e.g., formate) for the glycine-supplemented growth of a serine-glycine auxotroph (ser1) was correlated with a lack of glycine decarboxylase activity. The presence of oxalate decarboxylase activity or glyoxylate decarboxylase activity did not overcome the one-carbon requirement. Another mutation characterized by the absence of oxalate decarboxylase activity did not introduce a one-carbon requirement. The presence and physiological significance of glycine decarboxylase activity in Saccharomyces are thus inferred.

Acetates↗