Search PubMed⌕ Search

Biomedical subjects

P Yeh

Publications and source records attributed to P Yeh.

43 records · Page 3Linked to original sources
PubMed1988

Nucleotide sequence of the lysA gene of Corynebacterium glutamicum and possible mechanisms for modulation of its expression.

Sequence analysis localized the lysA gene of Corynebacterium glutamicum strain AS019 within a 1.35 kb open reading frame, potentially encoding a 445 amino acid product. Immediately downstream from this gene we found a potential rho-independent transcription terminator, while the 5' flanking region (300 bp) harbors unusual topological and structural features, located in the vicinity of a potential ribosome binding site. Within this upstream region, enzymatic and genetic analyses indicated the occurrence of a promoter responsible for significant, although weak, expression of the encoded enzymatic activity. The same significant expression level was observed with a plasmid harboring an additional 0.5 kb of genomic information upstream from lysA, while its full expression apparently requires 2 kb of additional genomic information located immediately upstream from the cloned gene. The upstream sequence requirement apparently associated with the full expression of the lysA gene of C. glutamicum shows some similarity with the Escherichia coli system.

Amino Acid Sequence↗
PubMed1988

Pseudomonas aeruginosa diaminopimelate decarboxylase: evolutionary relationship with other amino acid decarboxylases.

The lysA gene encodes meso-diaminopimelate (DAP) decarboxylase (E.C.4.1.1.20), the last enzyme of the lysine biosynthetic pathway in bacteria. We have determined the nucleotide sequence of the lysA gene from Pseudomonas aeruginosa. Comparison of the deduced amino acid sequence of the lysA gene product revealed extensive similarity with the sequences of the functionally equivalent enzymes from Escherichia coli and Corynebacterium glutamicum. Even though both P. aeruginosa and E. coli are Gram-negative bacteria, sequence comparisons indicate a greater similarity between enzymes of P. aeruginosa and the Gram-positive bacterium C. glutamicum than between those of P. aeruginosa and E. coli enzymes. Comparison of DAP decarboxylase with protein sequences present in data bases revealed that bacterial DAP decarboxylases are homologous to mouse (Mus musculus) ornithine decarboxylase (E.C.4.1.1.17), the key enzyme in polyamine biosynthesis in mammals. On the other hand, no similarity was detected between DAP decarboxylases and other bacterial amino acid decarboxylases.

Amino Acid Sequence↗
PubMed1986

A shuttle vector system for Brevibacterium lactofermentum.

We have constructed a shuttle vector that replicates in Escherichia coli, Corynebacterium glutamicum and Brevibacterium lactofermentum, by fusion of a 4.4-kb cryptic plasmid isolated from B. lactofermentum and a derivative of pBR322. Resistance to erythromycin which is expressed in all three bacteria has been a useful selective marker. The frequency of homospecific transformation was 1.5 X 10(5) transformants/micrograms of hybrid plasmid DNA.

Brevibacterium↗
PubMed1985

Transfection of Corynebacterium lilium protoplasts.

A protoplast transfection system has been developed for a lysine-producing bacterium, Corynebacterium lilium, using the DNA of phage CL31. Phage CL31 is lytic and specific to C. lilium and has a genome of approximately 48 kb. The transfection procedure involves a polyethylene-glycol-mediated introduction of the DNA into lysozyme-treated cells and has a maximum efficiency of 3 X 10(4) transfectants per microgram DNA.

Bacteriophages↗
PubMed1984

Sympathetic innervation of lymph nodes in mice.

Noradrenergic innervation of popliteal and mesenteric lymph nodes in mice was examined with fluorescence histochemistry. Dense varicose plexuses entered the nodes with the vasculature in the hilar region and continued with the vasculature into the medullary region. Fine, delicate varicosities and small vascular plexuses continued into the cortical and paracortical regions surrounding the germinal centers; some varicosities ended among lymphocytes. A subcapsular plexus contributed fibers into the cortical and paracortical regions. Chemical measurements revealed the presence of norepinephrine in lymph nodes that was depletable with 6-hydroxydopamine. Depletion of norepinephrine from lymph nodes with this agent resulted in a diminished primary immune response in draining lymph nodes following subcutaneous injection of an antigen in two mouse strains, but had no effect in two other strains. These findings suggest that noradrenergic fibers innervate both the vasculature and parenchymal regions of lymph nodes, and may participate in the modulation of immune responses in these organs.

Adrenergic Fibers↗
PubMedDate not supplied

Adenovirus-mediated gene transfer in canine eyes: a preclinical study for gene therapy of human uveal melanoma.

BACKGROUND: Melanomas of the uveal tract are the most common intraocular malignancies in adults, with an incidence of six cases per million adults per year. Enucleation, which may enhance the dissemination of tumour cells into the systemic circulation, is still required for eyes with large tumours. Gene therapy is proposed as a new therapeutic approach for uveal melanoma management. METHODS: The potential of adenovirus-mediated gene transfer to normal eyes of two laboratory Beagles and in an iris tumour of a Great Dane were evaluated. Replication-defective adenoviral vectors (Adbetagal) were used to assess the feasibility, efficiency and safety of direct adenoviral delivery to the anterior chamber of normal eyes and to an iris tumour. The expression of angiostatin into the aqueous humour following an adenoviral-mediated delivery of human angiostatin (AdK3) was also investigated. RESULTS: The ciliary body was the area preferentially transduced after adenoviral injection into the anterior chamber. It was also demonstrated that a direct intratumoral injection of a recombinant adenovirus efficiently transduces a canine uveal melanoma. Western blot analysis performed on the aqueous humour revealed that the expression of the angiostatin recombinant protein in the aqueous humour correlated with the dose of AdK3 administered. Lymphocyte infiltrates at the site of AdK3 injection indicated induction of a strong cellular immune response, and humoral immune responses developed in all three dogs. CONCLUSIONS: The present study involving adenovirus-mediated gene transfer to dog eyes provides an essential basis for gene therapy treatment of uveal melanoma-bearing patients.

Adenoviridae↗