Lipopolysaccharide binding and antibacterial activities of a synthetic peptide representing amino acids 90-101 of bactericidal/permeability-increasing protein

The bactericidal/permeability-increasing protein (BPI) of polymorphonuclear leukocytes is a potent antibacterial agent specific for gram-negative bacteria. BPI can bind to lipopolysaccharide (LPS) and neutralize its toxicity. However, little is known about the specific site and mechanisms of the BPI involved in this LPS binding and antibacterial activities. This study compared the amino acid sequences among BPI, cecropin A, magainin 2, and polymyxin B, and identified a common structure among these four bactericidal agents. They share a basic amphipathic alpha helix motif (Baah). A short peptide that represents amino acids 90-101 of BPI was then synthesized to test if it possessed any LPS binding and antibacterial activities. Results from in vitro lymphocyte culture indicated this peptide was able to inhibit LPS-induced lymphocyte proliferation, suggesting that it may interact with LPS. This LPS binding ability of BPI peptide 90-101 was further supported by the results from HPLC assays which showed the mobility of the peptide shifted in the presence of LPS. Furthermore, the antibacterial spectra of this peptide and cecropin peptide 1-11 were very similar to that of polymyxin B, even though the antibacterial activities of these two peptides were less potent than that of polymyxin B. In addition, the antibacterial activities of these two peptides and polymyxin B were inhibited by free LPS or a high concentration of MgCl2. These results thus suggest that a common structure (Baah) and antibacterial mechanism may be involved in these antibacterial agents.

Therapeutic lamellar keratectomy in the management of experimental keratomycosis

Keratomycosis, a vision-threatening corneal infection, is a challenge to the ophthalmologist because it is often refractory to medical treatment. Surgical keratectomy may not only debulk the major infectious source but potentiate the intracorneal penetration of the antifungal agents. To evaluate the efficacy of keratectomy in managing the fungal corneal ulcer, three common keratomycosis models, Candida, Fusarium, and Aspergillus keratitis, were established in 46 eyes of 23 rabbits (each group had 14, 16 and 16 eyes respectively). Within each keratitis group, the infected eyes were randomly divided into equally numbered experimental and control subgroups. The eyes of the experimental subgroups underwent therapeutic lamellar keratectomy once the typical fungal corneal infection had developed after inoculation. Following keratectomy, eyes of both the treated and control groups received natamycin eyedrops and were regularly examined biomicroscopically. Our results showed that therapeutic lamellar keratectomy is beneficial in chronic, indolent keratitis, such as Candida and Fusarium keratitis, where it promoted corneal healing and shortened the duration of treatment required. The procedure is a valuable adjunctive measure for antifungal agents in these two types of keratitis. However, acute keratitis of the Aspergillus group did not benefit from keratectomy; in these cases, surgery may actually increase the risk of corneal perforation.

Rearrangement of bcl-2 genes in malignant lymphomas in Chinese patients

BACKGROUND

Only a small percentage of Asian patients with non-Hodgkin lymphoma may have follicular type disease. According to molecular analysis done recently, the incidence of rearrangement of bcl-2 gene in patients with follicular lymphoma was lower in Japan than in the United States, suggesting possible geographic or racial differences between Asian and Western populations. The current study was undertaken to obtain data from Taiwan to compare with data from Japan, Hong Kong, and Western countries.

METHODS

Using probes of genomic 5' bcl-2, major breakpoint region (mbr) and minor breakpoint cluster region (mcr) for the breakpoint cluster region of the bcl-2 gene, genomic DNA samples from 55 patients with B-cell lymphoma (17 with follicular type and 38 with diffuse type) were analyzed by Southern blot analysis.

RESULTS

Eleven patients had bcl-2 gene rearrangement, including 9 of 17 (52.9%) patients with follicular lymphoma and 2 of 38 (5.3%) patients with diffuse B-cell lymphoma. Nine patients had the breakpoint located within the mbr, one at both the mbr and the 5' bcl-2 regions, and the other had bcl-2 translocation with involvement of the mcr. DNA fragment of bcl-2 was found to comigrate with JH genes in all patients with follicular lymphoma and diffuse lymphoma who had bcl-2 rearrangement at mbr. The remaining patient who had bcl-2 translocation at mcr had no comigration with JH, Jk, or C lambda genes.

CONCLUSIONS

Despite the low incidence of follicular lymphoma in Chinese patients, the incidence of bcl-2 gene involvement was higher in patients from Taiwan than in those from Japan and Hong Kong, but similar to the incidence of those from Western countries.

Transcatheter double-blade valvotomy for the treatment of valvar pulmonary stenosis

A transcatheter double-blade valvotome for cutting a stenotic pulmonary valve has been devised. The valvotome consists of a retractable rhomboid structure at its tip, with a blade on each side of its proximal half. By tugging the extended blades from the pulmonary artery to the right ventricle it is possible to tear the stenotic valve. After animal experiments proved the feasibility and safety of this method, it was used in three children with pulmonary stenosis. The results were encouraging.

Purification of carp growth hormone and cloning of the complementary DNA

The growth hormone (GH) was isolated and purified from common carp (Cyprinus carpio) pituitary glands by salt precipitation and HPLC on reverse-phase C18 columns. The carp GH cDNA was synthesized and cloned in Escherichia coli using EcoRI linkers and pBR322 as vector. The positive clones were selected and sequenced. The full-length carp GH cDNA contains 1187 nucleotide basepairs with an open reading frame coding for the precursor form carp GH of 210 amino-acid residues. The partial amino-acid sequence from the protein completely agrees with that derived from the cDNA, with serine as the first residue in mature carp GH preceded by a 22-residue hydrophobic signal peptide. Comparison of the amino-acid sequence of carp GH with those of various species reveals positional identity at 32.4%, 38.8%, 42.0%, 37.2%, 66%, 55% and 49% with GHs of man, rat, duck, bullfrog, salmon, tuna and yellow tail, respectively.

Intracellular oxidative cleavage of DNA in Escherichia coli by the copper-1,10-phenanthroline complex

Plasmid and chromosomal DNA of E. coli during exponential growth are cleaved after treatment with copper(II)-1, 10-phenanthroline complex (1:2) without providing any exogenous reductant. About 1500 copper molecules per cell are present as estimated by atomic absorption analysis. Within the cell the endogenous reducing substances may have participated in the sequential oxidative reactions, which lead to the damage of DNA. A portion of the resultant DNA fragments originates from plasmid DNA as demonstrated by hybridization tests.