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Biomedical subjects

L Meng

Publications and source records attributed to L Meng.

94 records · Page 6Linked to original sources
PubMedDate not supplied

Antisense TGF-beta2 immunotherapy for hepatocellular carcinoma: treatment in a rat tumor model.

BACKGROUND: The overexpression of transforming growth factor-beta (TGF-beta) in hepatocellular carcinoma (HCC) appears to induce immunosuppression toward the tumor cells. METHODS: A rat HCC cell line, Morris hepatoma rat cell line (MRH)-7777 (MRH), was transfected with antisense TGF-beta2 in pCEP-4 vector and used as immunotherapy against the development of wild-type tumors. An enzyme-linked immunosorbent assay (ELISA) confirmed that TGF-beta2 production was markedly lower for antisense modified cells as compared to wild-type tumor cells. Tumors were initiated by injecting MRH cells into the flanks of Buffalo rats. This was followed by biweekly vaccinations with irradiated MRH cells (unmodified, pCEP-4 alone, or antisense TGF-beta2 modified). RESULTS: In the group that received irradiated MRH unmodified cells, 55% of rats died from tumor burden, and 36% developed tumor regression. In the group that received irradiated MRH cells modified with pCEP-4 vector alone, 50% died from tumors and 33% had spontaneous regression. In animals treated with pCEP-4/TGF-beta antisense modified cells, none developed tumors. Cell-mediated cytotoxicity assays demonstrated a twofold increase in lytic activity in the effector cells of the animals treated with antisense modified cells. CONCLUSIONS: These results demonstrate the successful treatment of HCC tumors in rats by a HCC vaccine genetically altered with antisense TGF-beta2. Decreased production of TGF-beta in HCC vaccine enhances immunogenicity against wild-type HCC tumor cells.

Animals↗
PubMedDate not supplied

Evaluation of coagulase-negative staphylococcal isolates from serial nasopharyngeal cultures of premature infants.

The present study was undertaken to determine whether very low birth weight infants in a neonatal intensive care unit became colonized with virulent strains of coagulase-negative staphylococci (C-S) over time (i.e., those characterized as Staphylococcus epidermidis, slime positive, and/or multiply antibiotic resistant), and if so, whether the initial colonizing strains developed these characteristics or whether the strains themselves changed. Nasopharyngeal (NP) cultures were obtained weekly on 28 very low birth weight (less than 1750 g) infants hospitalized for a mean of 8 wk (range 4-15 wk). There were 105 isolates of C-S recovered from 96 cultures that were characterized by species, biotype, antibiotic susceptibility pattern, and slime production (screening parameters). Isolates from the same infant with highly similar screening parameters then underwent phage typing and plasmid analysis to increase the likelihood of establishing strain identity. C-S colonization rose from 12% on admission to 75% by wk 2, then gradually declined to 30% by wk 6 and remained stable through wk 10. There were no significant differences among C-S isolates from wk 1 compared with wk 10 of hospital stay with respect to distribution of species, slime positive, or multiply antibiotic resistant strains. One biotype of S. epidermidis was recovered from 46% of study infants, but only one infant was colonized with a predominant biotype of S. epidermidis throughout hospitalization. Thirteen pairs of isolates recovered from 12 of the infants on two or more wk were found to be identical by phage typing and plasmid analysis. Only seven of these 13 pairs of isolates had concordant results for all the screening parameters.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacterial Typing Techniques↗