Recent trend of pylephlebitis in Taiwan: Klebsiella pneumoniae liver abscess as an emerging etiology.

BACKGROUND AND AIMS: Pylephlebitis (septic thrombophlebitis of the portal venous system) is a rare complication of intra-abdominal infection. We aimed to investigate the recent trend of its etiology, clinical manifestation, and prognosis. METHODS: We retrospectively studied the etiology, clinical manifestation, and outcome by reviewing the medical records of all imaging-confirmed pylephlebitis cases diagnosed during the period 2002-2011 in a university hospital in Taiwan. To identify the risk factors for pylephlebitis, we randomly selected 160 patients with intra-abdominal infections but without pylephlebitis as the comparison group. RESULTS: We identified 35 cases of pylephlebitis. Most patients were men [29/35 (83 %)]. The median age of the patients was 57 years (range 35-90 years). Unspecified abdominal pain (18/35) and fever (10/35) were the most common clinical manifestations. Klebsiella pneumoniae liver abscess (7/35) and cholangitis (7/35) were the most common etiologies. Liver abscess was a risk factor for pylephlebitis (13/35 vs. 27/160, P = 0.01). With antibiotic therapy, there was no in-hospital mortality, but pylephlebitis was still associated with an excess hospital stay (22.2 ± 17.6 vs. 9.8 ± 7.1 days, P < 0.001). CONCLUSIONS: Our study results suggested a different pattern of pylephlebitis from previous Western literature. K. pneumoniae liver abscess (7/35) is an emerging etiology of pylephlebitis in Taiwan.

Microbial exo-polysaccharides for biomedical applications.

The productions and applications of various microbial exopolysaccharides have been under intensive researches over the past few decades. Some of these exopolysaccharides are commercial available and some are currently under intensive development; they include ionic heteropolysaccharide and neutral homopolysaccharide. These extracellular polymers constitute a structurally diverse class of biological macromolecules with a wide range of physiochemical properties which are the basis for the different applications in the broad fields of pharmacy and medicine. They have found applications in such diverse biomedical fields as ophthalmology, orthopedic surgery, tissue engineering, implantation of medical devices and artificial organs, prostheses, dentistry, bone repair and drug delivery.

Biomedical applications of chemically and microbiologically synthesized poly(glutamic acid) and poly(lysine).

This review article deals with the synthesis, physiochemical properties, and potential biomedical applications of two homo-poly amino acids. Poly-alpha-glutamic acid (alpha-PGA) and poly-alpha-lysine (alpha-PL) were synthesized by chemical synthesis. poly-gamma-glutamic acid (gamma-PGA) and poly-epsilon-lysine (epsilon-PL) were naturally occurring bio-materials that were produced by microbial fermentation. Poly(glutamic acid) (PGA) and poly(lysine) (PL) are water soluble, biodegradable, edible and nontoxic toward humans and the environment. As a result, they are suitable for various applications and have recently attracted considerable interest of the chemical industry. The distinguished features of PGA and PL also make them promising candidates for biomedical applications. The applications of PGA and PL in the areas of biomedical materials, drug delivery carriers and biological adhesives have been studied extensively and will be discussed in this review.

The production of poly-(gamma-glutamic acid) from microorganisms and its various applications.

This review article deals with the chemistry and biosynthesis of poly-(gamma-glutamic acid) (gamma-PGA) produced by various strains of Bacillus. Potential applications of gamma-PGA as thickener, cryoprotectant, humectant, drug carrier, biological adhesive, flocculant, or heavy metal absorbent, etc. with biodegradability in the fields of food, cosmetics, medicine and water treatments are also reviewed.

Production of a biopolymer flocculant from Bacillus licheniformis and its flocculation properties.

Bacillus licheniformis CCRC 12826 produced extracellularly an excellent biopolymer flocculant in a large amount when it was grown aerobically in a culture medium containing citric acid, glutamic acid and glycerol as carbon sources. The biopolymer flocculant was an extremely viscous material with a molecular weight over 2 x 10(6) by gel permeation chromatography. It could be easily purified from the culture medium by ethanol precipitation. It was shown to be a homopolymer of glutamic acid by amino acid analysis and thin layer chromatography and presumed to be poly-glutamic acid (PGA). This bioflocculant efficiently flocculated various organic and inorganic suspensions. It flocculated a suspended kaolin suspension without cations, although its flocculating activity was synergistically stimulated by the addition of bivalent or trivalent cations Ca2+, Fe3+ and Al3+. However, the synergistic effects of metal cations were most effective at neutral pH ranges. The comparison of the flocculating activity between the present biopolymer and a commercial lower molecular weight product showed that the biopolymer of the present study had much higher activity. The high productivity and versatile applications of PGA make its development as a new biodegradable, harmless, biopolymer flocculant economical and advantageous.

Surface-induced conformational switching in amphiphilic peptide segments of apolipoproteins B and E and model peptides.

The conformational and surface-binding properties of a synthetic peptide corresponding to Tyr-apolipoprotein B-100(1000-1016) amide, SP-4, which was previously shown to mimic the focal accumulation pattern of LDL on the healing de-endothelialized rabbit aorta [Shih et al. (1990) Proc. Natl. Acad. Sci. USA 87, 1436-1440], have been investigated. SP-4 behaves as an amphiphilic alpha-helical peptide at the air-water interface and bound to siliconized quartz slides. However, its N alpha-acetylated analogue formed beta-sheet structures at the air-water interface. Nonhomologous peptide models of SP-4 also exhibited mixed alpha-helical and beta-sheet surface-binding behavior. Peptides corresponding to the cationic apolipoprotein (apo) B/E receptor binding regions of apoE (SP-2) and apoB (SP-11) were also studied. SP-2 behaved as an amphiphilic alpha helix, but, surprisingly, SP-11 formed surface-induced beta-sheets. These results demonstrate that all of the peptides studied have surface-binding properties, and suggest further that either alpha-helical or beta-sheet peptide structures may determine the binding of LDL to the arterial wall or the apoB/E receptor.

Focal accumulation of an apolipoprotein B-based synthetic oligopeptide in the healing rabbit arterial wall.

The functions of surface-accessible domains of apolipoprotein (apo) B, the protein moiety of low density lipoprotein (LDL), are unknown, aside from the LDL receptor-binding domain, which lies toward the carboxyl-terminal end of apoB. Since LDL accumulation in arterial lesions does not depend on recognition of LDLs by a cell-surface receptor, we synthesized an oligopeptide with the sequence of the trypsin-accessible domain of apoB that lies closest to the amino-terminal end of the protein and compared its biological activity to that of another synthetic oligopeptide with the sequence of the heparin- and apoB/apoE receptor-binding domains of apoE. (Tyrosine was added at the amino-terminal end of each peptide to facilitate radiolabeling.) The 18-amino acid apoB-based peptide included residues 1000-1016 of apoB, for which no function has been previously described. In radioautographs, the 125I-labeled peptide accumulated focally at the healing edges of regenerating endothelial islands in the balloon-catheter deendothelialized rabbit aorta. In contrast, the 21-residue apoE-based peptide, which included residues 129-148 of apoE, accumulated diffusely and uniformly throughout the deendothelialized areas of the aorta. The data show that focal binding of the apoB-based peptide can delineate arterial lesions and suggest that this arterial wall-binding domain of apoB mediates accumulation of LDLs in arterial lesions.