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Biomedical subjects

W Lin

Publications and source records attributed to W Lin.

At least 73 records · Page 4Linked to original sources
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↗
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↗
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↗
PubMed1977

Membrane-bound ATPase of intact vacuoles and tonoplasts isolated from mature plant tissue.

Intact vacuoles were isolated from petals of Hippeastrum and Tulipa (Wagner G.J. and Siegelman, H.W. (1975) Science 190, 1298--1299). The ATPase activity of fresh vacuole suspensions was found to be 2--3 times that of protoplasts from the same tissue. 70--80% of the ATPase activity of intact vacuoles was recovered in tonoplast preparations. The antibiotic Dio-9 at 6mug/10(6) vacuoles or protoplasts causes 40% inhibition. However, only the protoplast ATPase is sensitive to oligomycin. N,N'-dicyclohexylcarbodiimide (DCCD) slightly stimulates ATPase activity in both vacuole and protoplast suspensions, whereas ethyl-3-(3-dimethylaminopropyl carbodiimide) (EDAC) strongly inhibits. Spectrophotometric studies show that in the petal the vacuolar contents have a pH of 4.0 for Tuplipa and 4.3 for Hippeastrum, whereas the intact isolated vacuole has an internal pH of 7.0 (in pH 8.0 buffer) for (Tulipa and about 7.3 for Hippeastrum. Internal ion concentrations of 150, 46, 30, 30 and 6 mM were found for K+, Na+, Mg2+, Cl-, and Ca2+ respectively, which are about the same as those in protoplasts.

Adenosine Triphosphatases↗
PubMed1976

Nonuniform biosynthesis of multiple hemoglobins in the adult rat and guinea pig.

Separation of adult rat bone marrow cells by the method of thin layer countercurrent distribution permits the analyses of 59Fe-tagged erythroid cells for the various multiple hemoglobins and the assignment of such hemoglobins to erythroid cells at different stages of their development. Of the six adult red cell hemoglobins, hemoglobin 5 is synthesized most actively in the earliest erythroid cell whereas hemoglobin 4 (the major hemoglobin of the red cell) is synthesized most actively in the latest erythroid cells, e.g. the reticulocyte. Experimental evidence also indicates that maturation of the erythroid cell is accompanied by a decreased rate of synthesis of hemoglobin 5. The earliest erythroid cells of the marrow contain two hemoglobins, 7 and 8, which are absent in the adult red cell. Similar studies with the guinea pig confirm the nonuniform biosynthesis of its two hemoglobins and suggest that the phenomenon may be a general one among mammalian multiple hemoglobins.

Amino Acid Sequence↗
PubMed1976

Effects of different levels of dietary iron on pregnancy superimposed upon growth in the rat.

The effects of feeding four levels of dietary iron, 10, 50, 250 and 1.250 mg/kg were studied during pregnancy in growing and adult rats. Hematological measurements, plasma iron and total iron binding capacity, and iron content in liver, spleen and tibia were compared relative to pregnancy, diet and growth. Iron content in fetuses and fetal livers were compared relative to diet and growth of the dams. All parameters were lowest in rats fed the 10 mg Fe/kg diet. The highest level of iron fed, 1,250 mg/kg, resulted in increased iron content in liver, spleen and tibia of all treatment groups but did not alter hematological values or fetal iron content. Pregnant rats fed any of the four levels of iron had significantly lower Hb, Ht, total and storage iron concentration and ferritin and hemosiderin iron in liver than nonpregnant rats fed the same levels. The level of dietary iron needed by growing pregnant rats for maximal iron content in fetuses and fetal livers was between 50 and 250 mg Fe/kg which was fivefold that needed to obtain maximal hemoglobin concentration in dams. However, adult pregnant rats only needed between 10 to 50 mg Fe/kg for both maximal iron stores in fetal tissues and maximal hemoglobin concentration.

Animals↗
PubMedDate not supplied

Lumen definition in MR angiography.

Factors affecting blood vessel lumen definition for two-dimensional and three-dimensional inflow magnetic resonance (MR) imaging methods are considered. Vessel definition is affected (a) by the amount of dephasing of the blood in the vessels, both for uncompensated and velocity-compensated gradients; (b) by the image reconstruction technique (normal Fourier reconstruction when asymmetric echoes are collected or a maximum-intensity projection technique in post-processing); (c) by loss of signal due to T2* dephasing; (d) by misregistration; (e) by vessel wall motion; and (f) by partial-volume effects. The first two factors were found to dominate for resolution on the order of 1 mm3. To overcome these dephasing problems, the authors developed asymmetric echo, velocity-compensated sequences with TEs as short as 4.8 msec. The data were then reconstructed with an iterative partial Fourier algorithm, enabling improved lumen definition to be obtained in phantoms and in vivo.

Artifacts↗
PubMedDate not supplied

Gadolinium-enhanced high-resolution MR angiography with adaptive vessel tracking: preliminary results in the intracranial circulation.

To overcome problems associated with poor contrast between vessels and background tissue in time-of-flight magnetic resonance angiography, the role of intravenous gadopentetate dimeglumine in conjunction with a postprocessing adaptive vessel tracking scheme was studied. Vessel tracking makes it possible to discriminate arteries from veins, to prevent problems associated with other bright tissues on maximum-intensity projections, and to increase the signal-to-noise ratio. Short, asymmetric, velocity-compensated field echoes were used in conjunction with high-resolution imaging techniques to spatially discriminate between adjacent vessels and stationary background tissue. Gadopentetate dimeglumine was shown to be useful for visualization of small vessels, aneurysms, and regions of slow flow, when used with this post-processing scheme.

Adolescent↗
PubMedDate not supplied

Automated local maximum-intensity projection with three-dimensional vessel tracking.

Despite the simplicity and widespread acceptance of the maximum-intensity-projection (MIP) technique for displaying three-dimensional (3D) magnetic resonance angiographic data, several disadvantages are associated with MIP as it is applied to all of the 3D data. These include elevated noise level, reduced contrast between small vessels and background tissue, and the inability to distinguish arteries from veins. The authors have developed a 3D vessel tracking method combined with a local MIP around a given vessel to complement conventional MIP and alleviate these problems. The method is referred to as a traveling MIP (TMIP). TMIP was evaluated in both patients and healthy volunteers. The results indicate that TMIP provides better contrast between vessels and background tissue, better lumen definition, and better vascular visualization than either MIP or vessel tracking alone.

Algorithms↗
PubMedDate not supplied

Preparation of human serum albumin microspheres by a novel acetone-heat denaturation method.

Human serum albumin (HSA) microspheres have been produced in the size range of 200 nm to 10 microns by the controlled addition of acetone to an aqueous solution of HSA, followed by stabilization of the formed microspheres at an elevated temperature. Microspheres produced by this acetone-heat denaturation method could be stabilized at relatively low temperatures (75 degrees C) over a short time period (15-30 min). The acetone-heat denaturation method is different from the traditional oil/water technique for preparation of HSA microspheres, both in terms of production method and the avoidance of high temperatures (> 100 degrees C) and extended heating times (> 30 min) for stabilization. This paper describes the influence of process conditions, such as volumes of acetone and HSA concentration, on the formation of the microspheres and their morphological characteristics. A loading efficiency of 8 per cent was achieved for the HSA microspheres when using rose bengal as a model compound. The release of rose bengal from the microspheres in phosphate buffered saline at 37 degrees C was dependent on the presence of the surfactant Tween 80, and varied from a 5 per cent release in 14 days in the absence of surfactant to a 50 per cent release in 8 h in the presence of surfactant.

Acetone↗