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Biomedical subjects

W Lin

Publications and source records attributed to W Lin.

At least 55 records · Page 3Linked to original sources
PubMed1984

Excretion of RNA catabolites by rats with hepatoma transplants.

Rats with transplants of Morris Hepatoma 5123 excreted in their urine greater than normal amounts of modified nucleosides and bases, catabolites of RNA. Despite rapid growth of the neoplasm, the elevated levels did not appear until 22 days after inoculation with the tumor. With tumor progression, there were increased levels and number of these catabolites. This study also suggests that the source of the elevated RNA catabolites is mainly from the host RNA rather than from tumor tissue and also that mRNA and rRNA as well as tRNA may contribute to the urinary levels.

Animals↗
PubMed1984

Resistance of chickens immunized against Mycoplasma gallisepticum is mediated by bursal dependent lymphoid cells.

Newly hatched chickens were significantly protected against challenge by the virulent S6 strain of Mycoplasma gallisepticum after vaccination with the TS 100 mutant. Removal of the thymus did not abolish the protective effect of the vaccine, but removal of the bursa of Fabricius did. The results suggest that the resistance induced by vaccine is mediated by the bursal-dependent lymphoid cells.

Animals↗
PubMed1984

Urinary catabolites of ribonucleic acid as cancer markers: a preliminary report of their use in patients with lung cancer.

Rats with aflatoxin-B1-induced hepatomas and dimethylnitrosamine-induced nephroblastomas excreted greater than normal amounts of urinary modified nucleosides and bases, catabolites of ribonucleic acid (RNA). Although both neoplasms caused increased excretions of the same catabolites, their quantitative profiles differed, suggesting that it may be possible to distinguish between tumors. Rats with transplanted tumors (e.g., hepatomas and osteogenic sarcomas) did not excrete elevated levels of urinary RNA catabolites until approximately 20 days after transplantation despite rapid growth of the tumor for the first 15 days. These data suggest that the source of the elevated levels of these excretory products may be the host's tissue RNA. Preliminary studies in human beings with lung cancer showed marked elevation of one or more urinary RNA catabolites. Resection of the diseased tissue in 2 patients caused a drop in levels. The measurement of urinary RNA catabolites may be useful in the diagnosis, prognosis, and evaluation of therapy in patients with lung cancer.

Aflatoxin B1↗
PubMed1984

Subcellular distribution of viral structural proteins during simian virus 40 infection.

The amounts of simian virus 40 structural polypeptides Vp1, Vp2, and Vp3 in different subcellular fractions at various times after lytic infection were determined by a quantitative immunoblotting procedure. Simian virus 40-infected cells were lysed with a buffer containing Nonidet P-40 to yield a soluble fraction. The Nonidet P-40-insoluble fraction was further fractionated in the presence of deoxycholate and Tween 40 to yield a soluble fraction (cytoskeletal) and an insoluble fraction (Nuc), which is primarily cell nuclei. At 33 h postinfection, the majority of viral structural proteins was found in the cell nucleus, whereas, at 48 to 65 h postinfection, Vp1 was distributed evenly among all cell fractions and Vp2 and Vp3 were found predominantly in the cytoskeletal and Nuc fractions. Thus, not all of the viral polypeptides synthesized in the cytoplasm migrated into the cell nucleus. Throughout infection, the molar ratio (Vp3/Vp2) was rather constant in all subcellular fractions, indicating that the synthesis or processing or both of Vp2 and Vp3 are coordinately regulated. The molar ratio of Vp1/(Vp2 + Vp3) varied among the fractions. The Vp1/(Vp2 + Vp3) molar ratio in the soluble fraction varied during the course of infection; however, constant ratios were maintained in the cytoskeletal and Nuc fractions. Thus, the mechanism which controls the movement of Vp1 to different compartments of the cell appears to be different from that of Vp2 and Vp3. The Vp1/(Vp2 + Vp3) value in the Nuc fraction was similar to the ratio found in virus particles. The constant molar distribution of Vp1, Vp2, and Vp3 in the Nuc fraction throughout infection suggests that there is a specific mechanism which regulates the transport of viral structural proteins. These results support the hypothesis that the structural proteins of simian virus 40 are transported into the cell nucleus in precise proportions.

Animals↗
PubMed1984

Utilization of temperature-sensitive mutants of Mycoplasma gallisepticum to prevent air sac infections.

Three stable temperature-sensitive (ts) mutants were obtained by treating the S6 strain of Mycoplasma gallisepticum with 50 micrograms/ml of nitrosoguanidine. These mutants were morphologically and serologically indistinguishable from the parent S6 strain. Mutants ts 37 and ts 102 were apathogenic, and ts 100 was moderately pathogenic to chickens when inoculated directly into the air sac. To turkeys, ts 37 remained apathogenic, ts 102 was slightly pathogenic, and ts 100 was highly pathogenic, Intranasal immunization of newly hatched chickens with any of the mutants resulted in antibody production, but only ts 100 and ts 102 protected chickens against experimental M. gallisepticum infections 3 weeks later. Vaccination of 2-day-old turkeys with ts resulted in erratic antibody response; however, 5 weeks after immunization, turkeys were able to resist challenge with the virulent S6 strain at a highly significant level.

Agglutination Tests↗
PubMed1983

On the electrotransfer of polypeptides from gels to nitrocellulose membranes.

The conditions which affect the elution of polypeptides from polyacrylamide gels by electrophoresis and polypeptide-nitrocellulose interactions have been studied. The rate of elution of polypeptides from a 15% sodium dodecyl sulfate-polyacrylamide gel is dependent on the molecular weight of the individual polypeptides, which is in agreement with the results of W. N. Burnette (Anal. Biochem. 112, 195 (1981)). We also observed that current density affects the rate of elution. Polypeptides smaller than 20,000 daltons pass through pores of 0.45 microns, but not through the pores of 0.1-microns nitrocellulose membranes during electrophoresis. The nonionic detergent NP-40 inhibits the binding of polypeptides to nitrocellulose and removes prebound polypeptides from the membranes. Amido black and Coomassie blue staining and destaining processes do not remove the bound polypeptides from the membranes, but may affect the antigenicity of polypeptides. Polypeptides immobilized on nitrocellulose can be stored at -70 degrees C for future use.

Antigens, Viral↗
PubMed1983

Comparison of urinary modified nucleosides and bases in rats with hepatomas and nephroblastomas.

Hepatomas were induced in rats with aflatoxin B1, and nephroblastomas with dimethylnitrosamine. Microscopic examination of livers of aflatoxin-treated rats revealed multinodular hepatocyte hyperplasia at 8 months, and by 13 months all rats had hepatomas. Nephroblastomas were observed by 4 months and by 8 months all rats had developed them. The urinary excretion of several modified nucleosides and bases by normal rats is dependent on body weight and reflects, to a certain extent, their concentrations in tissue tRNA. Increased levels of several modified nucleosides and bases were found in all rats that had cancer. Rats with hepatomas excreted essentially the same modified nucleosides and bases as did those with nephroblastomas; the quantitative patterns of excretion were different, however, suggesting that the urinary modified nucleosides and bases may be used to differentiate between neoplasms. Although the increase in urinary modified nucleosides and bases by tumor-bearing animals results primarily from more rapid turnover of neoplastic tRNAs, the data indicate that increased turnover of mRNA and possibly rRNA may occur in neoplastic tissue. Preliminary data suggest that increases in urinary modified nucleosides and bases may occur during a precancerous stage. The urinary pattern of modified nucleosides and bases by rats with hepatomas is altered if another primary tumor is present. The results obtained from these studies support the use of modified nucleosides and bases in urine as biochemical markers of cancer.

Aflatoxin B1↗
PubMed1983

Visualization of antigens attached to cytoskeletal framework in animal cells: colocalization of simian virus 40 Vp1 polypeptide and actin in TC7 cells.

Actin and the simian virus 40 viral structural polypeptide Vp1 are observed to be present on cytoskeletal fibers of virus-infected TC7 cells, when these antigens in detergent-extracted whole cell mounts were labeled by specific antibodies and colloidal gold particles coated with a second antibody. In both cases, actin and Vp1 were found associated with fibers and fiber-associated electron-dense materials. Patches or clusters of colloidal gold particles denoting the presence of either Vp1 or actin were found on fibers uniformly distributed throughout the cytoplasm. By using simultaneous decoration of the two antigens with colloidal gold particles of different diameters, it was shown that the majority of Vp1 appears attached to cytoskeletal fibers in association with cellular actin. When Vp1 and actin were decorated with Imposil and ferritin simultaneously in infected cells that were fixed first and then permeabilized with saponin, both labels were found in the same spatial domain of the cell cytoplasm. Thus, the colocalization of Vp1 and actin on the cytoskeletal framework seems to reflect their actual state in the living cells. The electron-dense material to which colloidal gold particles localize in our cytoskeletal preparations may be the remnants of subcellular structures with which actin and Vp1 are both associated in intact cells.

Actins↗
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↗
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↗