Search PubMed⌕ Search

Biomedical subjects

Z Liu

Publications and source records attributed to Z Liu.

At least 1,387 records · Page 77Linked to original sources
PubMed1987

The rise of technology in Chinese hospitals.

Chinese hospitals in the 1980s are in the midst of a technological revolution. Based upon data from several regions in China, this paper describes the political, organizational, economic, and philosophical changes which have accompanied the shift in focus from primary care medicine to high technology tertiary care. The increased authority of physicians, greater contact with the West, and increased funding for medical equipment are key factors in these changes. Although the Chinese state continues to control the administration and financing of most hospitals, the decentralizing reforms of Deng Xiaoping have undermined its ability to effectively plan for, and assess new technology. At present, limited resources prevent most regions from excessive technology acquisition, but the state must rebuild its planning capacity in order to foster rational allocation of scarce medical resources.

Capital Expenditures↗
PubMed1987

Pontentiometric cyanine dyes are sensitive probes for mitochondria in intact plant cells : kinetin enhances mitochondrial fluorescence.

Selected fluorescent dyes were tested for uptake by mitochrondria in intact cells of barley, maize, and onion. The cationic cyanine dye 3,3'-diheptyloxacarbocyanine iodide [DiOC(7)(3)] accumulated in mitochondria within 15 to 30 minutes without appreciable staining of other protoplasmic constituents. The number, shape, and movement of the fluorescent mitochondria could be seen readily, and the fluorescence intensity of the mitochondria could be monitored with a microscope photometer. Fluorescence was eliminated in 1 to 5 minutes by the protonophore carbonyl cyanide m-chlorophenylhydrazone (CCCP) indicating that maintenance of dye concentration was dependent on the inside-negative transmembrane potential maintained by functional mitochondria. Fluorescence of prestained mitochondria was enhanced within 5 to 10 minutes after addition of 0.1 millimolar kinetin to cells. The fluorescence in kinetintreated cells was dissipated by CCCP. These results suggest that kinetin interacted with respiratory processes resulting in higher potential across the mitochondrial membrane.

Journal Article↗
PubMed1986

Estimation of total arterial compliance: an improved method and evaluation of current methods.

Determination of arterial compliance in vivo has long interested physiologists. Most current methods for estimating this parameter assume that compliance is constant, i.e., that arterial pressure-volume (P-V) relations are linear, and they also assume that diastolic aortic pressure decay is an exponential function of time. Both of these assumptions, however, are questionable. This study proposes improved methods of estimating compliance based on a Windkessel model of the arterial system but which utilize the area under the pressure tracing rather than the waveform itself. Formulations accounting for both linear and three hypothetical nonlinear arterial P-V relations (exponential, logarithmic, and parabolic) are presented. Data from patients with congestive heart failure and hypertension are used for illustration. Compliances assuming linear P-V relations are reasonably close to those assuming nonlinear P-V relations only at mean aortic pressure. At end-diastolic pressure the linear assumption underestimates and at peak systolic it overestimates the compliances obtained assuming nonlinear P-V relations. The simpler linear assumption still allows a first approximation to compliance, but we show that existing methods for obtaining compliance under this assumption have severe theoretical as well as practical shortcomings. Our proposed method avoids these shortcomings primarily because deviations from an exact exponential form of the pressure wave have less influence on these compliance estimates than currently used methods.

Arteries↗
PubMed1986

Application of avidin-biotin-peroxidase complex method with a monoclonal antibody to human Ia-like antigen in immunoelectron microscopy.

Monoclonal antibody (MAb) to human Ia-like (HLA-DR) antigen was applied with the avidin-biotin-peroxidase complex (ABC) immunostaining method to localize the Ia-like antigen at the electron microscopic level. Our results indicated that in human tonsils and adenoids fixed with 4-6% phosphate-buffered paraformaldehyde for 4-6 hr, sharply delineated electron-dense products of the antigen and antibody complex were detectable on the outer cell membranes of lymphoblasts, lymphocytes, reticular cells, and macrophages. In our study, the vibratome sections of the paraformaldehyde-fixed, pre-embedding immunostained tissues consistently showed more satisfactory morphology than frozen sections. The combined use of the anti-human Ia monoclonal antibody and the ABC procedure with paraformaldehyde fixation provides a simple and sensitive method to study at the ultrastructural level the Ia-like antigen-bearing cells, which are vital in the immune response.

Adenoids↗
PubMed1986

Association of the translocation (15;17) with malignant proliferation of promyelocytes in acute leukemia and chronic myelogenous leukemia at blastic crisis.

Cytogenetic studies were performed on nine patients with acute promyelocytic leukemia. Every patient had an identical translocation (15;17) or, in one case, a variant three-way rearrangement between chromosomes 7, 15, and 17. Another patient with chronic myelogenous leukemia was examined at the time of blastic crisis when the patient's bone marrow was infiltrated by hypergranular promyelocytes and blasts. Bone marrow cells contained a t(15;17) as well as a Ph1 chromosome. Only the latter abnormality was observed in the chronic phase of the disease. The translocation (15;17) was detected in all ten patients when bone marrow or peripheral blood cells were cultured for 24 hours prior to making chromosome preparations. However, the t(15;17) was not seen in three of these same cases when bone marrow cells were processed directly. These findings indicate that the t(15;17) is closely associated with acute proliferation of leukemic promyelocytes and that detection of this karyotypic defect may be influenced by the particular cytogenetic processing method used in different laboratories. An analysis of the banding pattern in the variant translocation provided additional evidence favoring chromosomal breakpoints at or very near the junction between bands 17q12 and 17q21 and at 15q22.

Bone Marrow↗
PubMed1985

High-performance liquid chromatographic separation and determination of 2-(diethylamino)ethyl diphenylpropylacetate and its metabolites from biological samples.

A high-performance liquid chromatographic method for the determination of 2-(diethylamino)ethyl diphenylpropylacetate (SKF 525-A; Proadifen), its two deethylated metabolites and a hydrolytic metabolite in biological samples has been developed. From many solvent systems investigated the compounds are best separated on an ODS/Sil-X column using an acetonitrile-phosphate buffer system containing 0.2% decylamine. The use of acetonitrile overcomes limitations associated with previously published methods for separating basic compounds where decylamine was used in a methanolic eluent. With the sampling procedures used, overall recoveries from biological tissues were around 80%. The chromatographic system also separates three tricyclic antidepressants which can be used as internal standards.

Animals↗
PubMed1985

Selective changes in cytochrome P-450 and UDP-glucuronosyltransferase subpopulations following partial hepatectomy in rats.

Following 65% hepatectomy in adult male rats, the cytochrome P-450 in the residual liver decreased continuously from 1.0 to approximately 0.5 nmol/mg protein over a period of 2 to 3 days, and then recovered slowly to presurgery values by 14 days. In contrast UDP-glucuronosyltransferase activity (per mg protein) declined (25 to 40% depending on the aglycone used to assay the enzyme) for only 1 day, with a rapid recovery to presurgery values by 5 days. Transferase activity toward estrone overshot control values during recovery and was elevated above its presurgery value at 7 days. The changes in drug-metabolizing enzymes were accompanied by a surge in mitosis which peaked at 2 days. The extent of the decline in cytochrome P-450 and the increase in the mitotic index were proportional to the amount of liver removed. The decline in cytochrome P-450 was selective for cytochrome P-450 which elutes in the void volume upon anion-exchange high-pressure liquid chromatography of solubilized microsomes. Accompanying the decline in cytochrome P-450 in this eluate was a decline in protein(s) with a molecular weight of 51,500. The decline in cytochrome P-450 also caused disproportionate decreases in microsomal ethylmorphine N-demethylase activity and metabolic-intermediate complex formation from norbenzphetamine and SKF 525-A, but not in p-nitroanisole O-demethylase activity, metabolic-intermediate complex formation from isosafrole or metyrapone binding to cytochrome P-450.

Animals↗
PubMed1985

Cytochrome P-450 ligands: metyrapone revisited.

Expressing metyrapone interactions with ferrous cytochrome P-450 as ligand saturation by cytochrome, rather than the more conventional cytochrome saturation by ligand, an extinction coefficient of 68.5 +/- 1.8 mM-1 cm-1 for the metyrapone complex of dithionite-reduced rat hepatic microsomal cytochrome P-450 was derived. Utilizing this new extinction coefficient, the increased cytochrome P-450 present after phenobarbital induction was almost exclusively that which is able to both bind to metyrapone and form a metabolic-intermediate complex from norbenzphetamine. However, it was not the only subpopulation present in microsomes that was able to bind metyrapone, nor the only one capable of forming a metabolic intermediate complex from norbenzphetamine. Thus, neither technique alone can be used to quantitate the "phenobarbital-induced form" of cytochrome P-450.

Animals↗
PubMed1985

Selenium intake and metabolic balance of 10 men from a low selenium area of China.

Selenium intake and urinary and fecal Se excretion of 10 healthy men from a low Se area in China were determined for three consecutive days, in summer, fall, and winter of 1983, and the spring of 1984 while self-selected diets were being consumed. Mean daily Se intake was 8.8 micrograms/day with a range of 2.3-35.5 micrograms/day, and was far below the recommended range of safe and adequate Se intake of 50-200 micrograms Se/day (National Academy of Sciences/National Research Council). Mean urinary and fecal Se outputs were 3.7 and 3.4 micrograms Se/day, respectively. Mean Se balance during this time was +1.8 micrograms Se/day. Apparent absorption of Se approximated 57%. The low Se intake in this area is a cause for concern since the residents of Molimo may be at risk for Se deficiency diseases.

Adult↗