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Biomedical subjects

W Lin

Publications and source records attributed to W Lin.

At least 37 records · Page 2Linked to original sources
PubMed1988

Bacterial survival and thermal responses of beef loaf after microwave processing.

The effects of wrapping product in polyvinylidene chloride (PVDC) film, load size (150, 600 and 1200 g loaves), microwave output power (713 +/- 5 W and 356 +/- 3 W at 2450 MHz) and processing time on bacterial survival were evaluated in beef loaf. Specifically the survival of aerobic flora, and inoculated Staphylococcus aureus (ATCC 6538) and Escherichia coli (O157:H7) were assessed. Results showed that beef loaf wrapped in PVDC film had lower levels of survival for aerobic bacteria, S. aureus and E. coli than unwrapped beef loaf. When beef loaf was exposed to the same microwave dose (watts x minutes processed/grams of food), the percent of survival remained the same, regardless of load size or microwave output power. Exposed microwave dose, which correlated highly to percent of bacterial survival (R2 = 0.8-0.83) and end point temperature (R2 = 0.84), is suggested in place of output power, time or temperature as a predictor of microbial quality in foods that have been microwave processed.

Animals↗
PubMed1988

Bone-cell-stimulating substance.

An acid-pepsin extract of ground cancellous calf bone contains a bone-cell-stimulating substance (BCSS) that is active in the intact rat and in bone cultures. A single injection of a suspension of BCSS adjacent to the radius-ulna complex of a rat significantly increased appositional bone formation in a dose-dependent manner. The pattern of new bone deposition differed from that caused by nonspecific irritants. A suspension or water-soluble extract of BCSS significantly increased DNA and collagen synthesis in organ cultures of diaphyseal pieces of 17-day-old fetal chick tibiae. Whether or not BCSS is different from any of the other bone-derived growth factors has not been established.

Animals↗
PubMed1987

Effect of transplanted osteogenic sarcoma on urinary RNA catabolites.

The usefulness of urinary RNA catabolites as markers for the early detection of a transplantable rat tumor and for the completeness of its resection was evaluated. The lack of correlation between tumor growth or size and the time of appearance of the elevated catabolites precludes their use for the early detection of cancer in this model. Complete removal of the tumor restored the elevated levels to normal but, if regrowth occurred, the elevated levels persisted, suggesting their possible use in monitoring the effectiveness of surgery. The data suggest that increased excretion of RNA catabolites is derived primarily from host tissue.

Animals↗
PubMed1986

The synthesis and transport of SV40 structural proteins.

The kinetics of the synthesis and transport of viral structural proteins, Vp1 and Vp3, and of actin in SV40 infected TC7 cells were studied. The newly synthesized proteins were found in the NP-40-soluble (Sol) fraction of the cell cytoplasm. The majority of newly synthesized viral structural proteins, destined for the cell nucleus for virion assembly, were transported to the cell nucleus (Nuc) between 10 and 30 min after synthesis, whereas the majority of newly synthesized actin remained in the Sol fraction of the cytoplasm, suggesting that some specific mechanism exists for selecting the proper sites for transport. The synthesis and transport of both Vp1 and Vp3 throughout infected cells were similar. However, there is a difference in the transport properties of these two proteins. Once Vp1 was synthesized, the mature Vp1 was transported to both the cytoskeletal (Csk) and the Nuc fractions in the absence of further protein synthesis, whereas the movement of Vp3 from the Sol to the Csk, but not to the Nuc fraction, was partially inhibited in the absence of protein synthesis. Modification of Vp1 occurred in the cell cytoplasm before transport to the cell nucleus. Its modification pattern suggests that the Csk is the site for the modification of Vp1. The efficiency of viral protein transport to the cell nucleus was diminished after 47 hr of infection. This trend was preceded by a decrease in the ability to incorporate label into actin 12 hr earlier in infection. Thus, some marking event appears to have occurred prior to the actual decrease in transport efficiency and the integrity of the cytoarchitecture appears to be important for viral protein transport.

Actins↗
PubMed1986

Push-pull perfusion of the hypothalamus and the caudate nucleus in conscious, unrestrained animals.

The present results further confirm the usefulness of the push-pull cannula to study the in vivo activity of several neural systems in conscious, freely moving animals. However, it is evident that the inflammatory reaction to the local injury induced by the cannula may have different consequences in the function of a particular brain area. In the caudate nucleus, the responsiveness of the dopaminergic terminals of the nigrostriatal DA system to local infusion of AMPH was clearly reduced after the first two to three weeks post cannula implant. In contrast, in the hypothalamus of the rat and the rabbit, the spontaneous fluctuating activity of the LHRH pulse generator remained unaffected during a two to three month period when several perfusions could be performed in the same animal. Further studies will be required to establish the reasons for such marked differences in response to injury of these two brain structures. Various neurochemicals can be measured simultaneously from the hypothalamus of conscious rabbits. The present results indicate that NE hypothalamic impulse flow increases during the afternoon whereas the impulse flow of DA (as estimated by DOPAC output) decreases or does not change. In rabbit No. 2, simultaneous measurement of hypothalamic NE release and LHRH release indicates an absence of correlation. In sharp contrast, the simultaneous measurement of prostaglandin E2 release and LHRH release from the hypothalamus of rabbit 2-ER revealed a closer association between these two neuronal events. Apparently the push-pull technique can be used to examine long-term seasonal as well as circadian (extended 24 hr perfusion) spontaneous changes in the activity of the LHRH pulse generator in individual animals. It seems that seasonal changes characterize the function of the rabbit LHRH pulse generator. Lastly, physiological doses of progesterone infused for short times directly into the hypothalamus of female rabbit stimulate the LHRH pulse generator of this species with marked increases in the amplitude of the LHRH signal. In conclusion, the PPP technique coupled to HPLC-EC and RIA procedures to measure localized release of neurotransmitters, metabolites, and neuropeptides simultaneously in the same perfusate samples from discrete brain areas appears to be a powerful technique in furthering our knowledge of the in vivo local neurochemistry of the brain of conscious, freely moving animals.

Animals↗
PubMed1985

Determination of valproic acid in plasma or serum by solid-phase column extraction and gas-liquid chromatography.

A simple, fast, sensitive, and inexpensive method is described for routine therapeutic monitoring of both total and free valproic acid (VPA) at therapeutic concentrations in seizure patients. The method uses solid-phase (Bond Elut) columns for the preliminary extraction of 100 microliters plasma or serum and gas-liquid chromatography (GLC) analysis, using 10% Carbowax 6000 on a Chromosorb WAW 80/100 column and alpha-methyl-alpha-ethylcaproic acid as an internal standard. The extraction efficiency for VPA at a concentration of 70 micrograms/ml is 98 +/- 4%. The calibration curve is linear in the range of 1.0-280 microliters/ml. The detection limit of VPA is 1.0 micrograms/ml. Syva enzyme multiplied immunoassay technique (EMIT) Free-Level filters were used in the analysis of free VPA from plasma. The described Bond Elut X GLC (BE X GLC) method was used to determine total drug concentrations in 56 VPA-treated patients, and the results were compared with those obtained by conventional liquid-liquid extraction X GLC analysis. The 44 sera involved were also analyzed by EMIT. In addition, BE X GLC was compared with the Abbott TDx system on an additional 21 specimens. Statistical agreement was excellent between BE X GLC and TDx, but poor between BE X GLC and liquid-liquid extraction X GLC. Agreement with the EMIT method was intermediate.

Chromatography, Gas↗
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↗