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Biomedical subjects

W Lin

Publications and source records attributed to W Lin.

At least 289 records · Page 16Linked to original sources
PubMed1983

Cadaver kidney allograft survival in a high-risk black population utilizing antilymphoblast globulin and low steroid therapy.

This study contrasts graft and patient survival in black and white high-risk populations receiving cadaveric renal allografts. In addition, factors affecting the outcome of black and white high-risk patients maintained on chronic hemodialysis for one year are studied. While immunosuppression and treatment of rejection with ALG appeared to improve graft and patient survival of both black and white allograft recipients, high-risk black patients tended to do poorly on chronic hemodialysis. Black high-risk patients, therefore, may be better candidates for transplantation.

Antilymphocyte Serum↗
PubMed1983

Predictive survival after kidney transplantation. An analysis of risk factors.

One hundred consecutive kidney transplants in 89 patients performed at a single center were analyzed to assess the relationship between patient survival and various high-risk factors present prior to transplantation. Each individual risk factor was given a relative weight which contributed to a cumulative risk index for each patient. Based on these risk indices, patients were placed in four risk categories: 1) good risk, 2) high risk, 3) very high risk, and 4) extremely high risk. Analysis of the survival data for each of these groups indicated that as the risk increased, survival decreased. Actuarial patient survival for the good risk group (n = 37) and high risk group (n = 27) were 97.2 per cent and 88.5 per cent, respectively. The very high risk group (n = 15) and extremely high risk group (n = 21) had decreased survival of 45.8 per cent and 38.2 per cent, respectively. Therefore, although our system of high-risk classification is not fully evolved, its application even in the present form could be of considerable aid in transplantation decision making.

Adult↗
PubMed1983

Metabolism of tRNA in rats with aflatoxin B1-induced hepatomas.

This study describes effects of aflatoxin B1-induced hepatomas on RNA metabolism in rats. At 4 and 24 hours after the administration of L-(14CH3)-methionine, tRNA was isolated from the livers and hydrolyzed enzymatically to nucleosides which were quantitatively measured by HPLC. Radioactivity of the nucleosides was also determined. The data indicate that although tRNA methylation may be more rapid in livers with hepatomas, catabolism of tRNA in tumorous tissue is slower than in control livers. The large increase in some radioactive methylated nucleosides and bases by the tumor-bearing rats during the 24-hour period following the administration of labeled methionine indicates increased turnover of mRNA and rRNA as well as tRNA. Since degradation of tumor tRNA appears to be delayed, the excessive amounts of the urinary methylated nucleosides must be derived from RNA in nonneoplastic tissue.

Aflatoxin B1↗
PubMed1982

Responses of corn root protoplasts to exogenous reduced nicotinamide adenine dinucleotide: Oxygen consumption, ion uptake, and membrane potential.

Addition of 1.5 mM NADH tripled the O(2) consumption in corn root protoplasts. The stimulation was temperature and pH dependent, specific to NADH, and accompanied by a 2- to 3-fold increase in K(+) and P(i) uptake into protoplasts. The increase in ion uptake was not due to the accumulation of NADH into protoplasts. The effect of exogenous NADH on O(2) consumption and ion uptake was also evident in corn root segments but to a lesser extent. A 20-mV hyperpolarization of protoplast membrane potential occurred on addition of NADH and was abolished by the uncoupler carbonyl cyanide p-trifluoromethoxyphenylhydrazone. Increases in cell volume of 30% and 40% were detected in response to NADH/H(+) and NADH/H(+)/K(+), respectively. The data are discussed in terms of a transmembrane redox reaction and the possibility that some part of the energy-linked ion transport may be driven by a NADH --> O(2) electron-transport system in the plasmalemma.

Journal Article↗
PubMed1982

Vacuolar localization of proteases and degradation of chloroplasts in mesophyll protoplasts from senescing primary wheat leaves.

Mesophyll protoplasts isolated from primary leaves of wheat seedlings were used to follow the localization of proteases and the breakdown of chloroplasts during dark-induced senescence. Protoplasts were readily obtained from leaf tissue, even after 80% of the chlorophyll and protein had been lost. Intact chloroplasts and vacuoles could be isolated from the protoplasts at all stages of senescence. All the proteolytic activity associated with the degradation of ribulose bisphosphate carboxylase in the protoplasts could be accounted for by that localized within the vacuole. Moreover, this localization was retained late into senescence. Protoplasts isolated during leaf senescence first showed a decline in photosynthesis, then a decline in ribulose bisphosphate carboxylase activity, followed by a decline in chloroplast number. There was a close correlation between the decline in chloroplast number and the loss of chlorophyll and soluble protein per protoplast, suggesting a sequential degradation of chloroplasts during senescence. Ultrastructural studies indicated a movement of chloroplasts in toward the center of the protoplasts during senescence. Thus, within senescing protoplasts, chloroplasts appeared either to move into invaginations of the vacuole or to be taken up into the vacuole.

Journal Article↗
PubMed1982

Isolation of NADH Oxidation System from the Plasmalemma of Corn Root Protoplasts.

A plasmalemma-bound NADH oxidation system (Lin 1982 Proc Natl Acad Sci USA 79: 3773-3776) in corn root protoplasts was isolated by a mild treatment of intact protoplasts with trypsin. The majority of NADH stimulated O(2) consumption activity of the protoplasts could be recovered in the supernatant isolated from the intact protoplasts which have been treated with trypsin. The activation energy of NADH oxidation in the supernatant is similar to that of the intact protoplasts (8.7 versus 9.4 kilocalories per mole per degree). Unlike that of the intact protoplasts, an Arrhenius plot of the temperature response (from 5 to 25 degrees C) of the activity in the supernatant shows no transition suggestive of a dissociation of the enzyme from the membrane. Trypsin treatment did not affect K(+) uptake into cell volume of the protoplast. However, the NADH-stimulated K(+) uptake and the increase of cell volume were greatly reduced. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of trichloroacetic acid-precipitated protein from the supernatant showed one extra peptide band with approximately 42 kilodalton molecular weight.

Journal Article↗
PubMed1981

Identification of antigenically related polypeptides at centrioles and basal bodies.

An antigen localized at the centriolar region has been identified by indirect immunofluorescence studies in African green monkey kidney, human, hamster, rat, and mouse cells. The antigen consists of two polypeptides of 14,000 and 17,000 daltons. A related antigen is also present at the basal body region in ciliated cells from chicken, cat, mouse, pig, steer, and rabbit trachea and from rabbit fimbria. Immunoelectron microscopy shows that the immunoreactive antigen is indeed located in the region around the basal bodies of ciliated cat tracheal cells. Thus, we have found an antigen that is common to a variety of cell types from many different animal sources and is specifically associated with both centrioles and basal bodies. The possible role of the antigen in differentiation is discussed.

Animals↗
PubMed1981

Subcellular localization of proteases in wheat and corn mesophyll protoplasts.

Mesophyll protoplasts were isolated from the leaves of wheat and corn seedlings. After purification the protoplasts were judged to be free of contaminating proteases in the isolation enzymes based on specific activity of the proteases in comparison to leaf tissue and their response to inhibitors that "differentiated" between leaf and isolation enzyme proteases. Wheat protoplasts showed rates of photosynthesis of 95 to 100 micromoles O(2) per milligram chlorophyll per hour, while corn exhibited rates of 35 to 85 micromoles O(2) per milligram chlorophyll per hour, indicating the intactness of the chloroplasts within the protoplasts. These chloroplasts were isolated from the protoplasts using the procedure of Robinson and Walker (1979 Arch Biochem Biophys 196: 319-323). Yields of 91 and 82% intact chloroplasts were obtained from wheat and corn, respectively, based on the distribution of ribulose bisphosphate carboxylase in wheat and NADP-malate dehydrogenase in corn. Vacuoles were obtained from the protoplasts using a modification of the techniques of Wagner and Siegelman (1975 Science 190: 1298-1299) and Saunders (1979 Plant Physiol 64: 74-78). The vacuoles were at least 98% free of protoplast contamination as determined by assaying for "marker" enzymes of chloroplasts, mitochondria, and endoplasmic reticulum. Assuming one vacuole per protoplast, the vacuoles contained 4% of the soluble protein of the protoplasts in wheat and 8% in corn. All the proteolytic activity associated with the degradation of ribulose bisphosphate carboxylase in the protoplasts could be accounted for by that localized within the vacuoles. Although the isolated chloroplasts always retained about 13% of the proteolytic activity of the protoplasts, this could be accounted for by that which became associated with the chloroplasts during their isolation.

Journal Article↗
PubMed1981

Inhibition of anion transport in corn root protoplasts.

The effects of several amino-reactive disulfonic stilbene derivatives and N-(4-azido-2-nitrophenyl)-2-aminoethylsulfonate on Cl(-), SO(4) (2-), and inorganic phosphate (Pi) uptake in protoplasts isolated from corn root tissue were studied. 4-Acetamido-4'-isothiocyano-2,2'-stilbenedisulfonic acid, 4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid, 4,4'-diamino-2,2'-stilbenedisulfonic acid, and NAP-taurine inhibited Cl(-) and SO(4) (2-) but not Pi and K(+) uptake in corn root protoplasts; whereas mersalyl inhibited Pi but not Cl(-) or SO(4) (2-) uptake. The rate of uptake of all anions decreased with increasing external pH. In addition, these reagents markedly inhibited plasmalemma ATPase activity isolated from corn root tissue. Excised root segments were less sensitive to Cl(-) and SO(4) (2-) transport inhibitors.

Journal Article↗
PubMed1980

Corn Root Protoplasts: ISOLATION AND GENERAL CHARACTERIZATION OF ION TRANSPORT .

A method was developed for the large scale and rapid isolation of intact viable corn root protoplasts. Pure and metabolically active protoplasts were collected using a flotation technique. Vital staining tests, light and electron microscopy, and measurements of basic metabolic processes indicated that the isolated protoplasts were metabolically active, and that the plasmalemma and other organelles were well preserved. The isolated protoplasts performed normal, active ion transport functions. Time course of K(+) and inorganic phosphate (H(2)PO(4) (-)) influx and the effects of external pH, carbonyl cyanide p-trifluoromethoxyphenylhydrazone, fusicoccin, and diethylstilbestrol on K(+) and inorganic phosphate influx and net H(+) efflux in isolated protoplasts correlated well with data obtained on root segments. Data presented indicated that isolated protoplasts from roots can be used to gain additional insights into the mechanism of ion transport in plant cells.

Journal Article↗
PubMed1979

The androgenic effect on the fine structure on the Harderian gland in the male hamster.

A sexual dimorphism of the hamster Harderian gland at the ultrastructural level has been reported. The effect of testosterone on the fine structure of the gland from castrated male golden hamsters is reported here. Harderian glands from the following three groups of animals were examined at regular intervals up to 60 days after castration: (1) castrated; (2) castrated-sham-injected, receiving 0.1 ml sesame oil per day; (3) castrated-testosterone-injected, receiving 2 mg testosterone propionate in 0.1 ml sesame oil per day. In groups 1 and 2, clusters of cylindrical tubules, typical of the male gland, decreased in number and disappeared almost completely 2 wailed in these two groups throughout the remaining period of experiment. On the other hand, these changes were prevented in the group of castrated animals maintained on testosterone propionate. It is concluded that castration modified the ultrastructure of the male hamster Harderian gland toward the female type and that daily administration of testosterone propionate prevented this change.

Animals↗
PubMed1979

Form variation in Escherichia coli K1: determined by O-acetylation of the capsular polysaccharide.

The chemical basis for the alternating antigenic change called form variation noted for the Escherichia coli K1-capsular polysaccharide has been shown by 13C nuclear magnetic resonance to be a result of random O-acetylation of C7 and C9 carbons of the alpha-2-8-linked sialic acid homopolymer. A serologic method (antiserum agar) was developed to identify and isolate the form variants. The O-acetyl positive and O-acetyl negative K1 polysaccharides had unique biochemical and immunologic properties. The O-acetyl-positive variants resisted neuraminidase hydrolysis in contrast to the susceptibility of the O-acetyl negative variant to this enzyme. In addition, O-acetylation altered the antigenicity of the O-acetyl polysaccharides. When injected as whole organisms, O-acetyl positive organisms produced anti-K1 -antibodies in rabbits specific for this polysaccharide variant. O-acetyl negative organisms were comparatively less immunogenic; however, antibodies induced by these organisms reacted with both K1 polysaccharide variants. Burros, injected with either variant, produced antibodies reactive with both K1 polysaccharides.

Acetylation↗
PubMed1979

Potassium and Phosphate Uptake in Corn Roots: Further Evidence for an Electrogenic H/K Exchanger and an OH/Pi Antiporter.

Evidence is presented that K(+) uptake in corn root segments is coupled to an electrogenic H(+)/K(+) -exchanging plasmalemma ATPase while phosphate uptake is coupled to an OH(-)/Pi antiporter. The plasmalemma ATPase inhibitor, diethylstilbestrol, or the stimulator, fusicoccin, altered K(+) uptake directly and phosphate uptake indirectly. On the other hand, mersalyl, an OH(-)/Pi antiporter inhibitor, inhibited phosphate uptake instantly but only slightly affected K(+) uptake. Collapse of the proton gradient across the membrane by (p-trifluoromethoxy) carbonyl cyanide phenylhydrazone resulted in immediate inhibition of K(+) uptake but only later inhibited phosphate uptake. Changing the pH of the absorption solution had opposite effects on K(+) and phosphate uptake. In addition, a 4-hour washing of corn root tissue induced a 5-fold increase in the rate of K(+) uptake with little or no lag, but only a 2- to 3-fold increase in phosphate uptake with a 30- to 45-minute lag. Collectively these differences strongly support the coupling of an electrogenic H(+)/K(+) -exchanging ATPase to an OH(-)/Pi antiporter in corn root tissue.

Journal Article↗