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Antimicrobial activity of human leuk...

Hilal, George E.

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Antimicrobial activity of human leukocyte defensin HNP-4 against Gram-negative bacteria.

紀錄類型:	書目-語言資料,印刷品 : Monograph/item
正題名/作者:	Antimicrobial activity of human leukocyte defensin HNP-4 against Gram-negative bacteria./
作者:	Hilal, George E.
面頁冊數:	61 p.
附註:	Adviser: Edwin L. Thomas.
Contained By:	Masters Abstracts International46-05.
標題:	Biology, Microbiology. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=1450495
ISBN:	9780549492504

Antimicrobial activity of human leukocyte defensin HNP-4 against Gram-negative bacteria.
Hilal, George E.

Antimicrobial activity of human leukocyte defensin HNP-4 against Gram-negative bacteria. - 61 p.

Adviser: Edwin L. Thomas.

Thesis (M.D.S.)--The University of Tennessee Health Science Center, 2008.

Human neutrophils (PMN cells) contain four peptides known as alpha-defensins or HNP 1-4. The peptides have broad-spectrum antibiotic activity. HNP 1-3 are major neutrophil components. They differ by only one amino acid residue. HNP-4 is found in small amounts, and has a different sequence. HNP-4 purified from neutrophils was reported to be 100-times more active than HNP-1 against Escherichia coli, suggesting that HNP-4 plays a special role in helping neutrophils kill Gram-negative bacteria.

ISBN: 9780549492504Subjects--Topical Terms:

1017734
Biology, Microbiology.

Antimicrobial activity of human leukocyte defensin HNP-4 against Gram-negative bacteria.
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020 $a 9780549492504
035 $a (UMI)AAI1450495
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100 1 $a Hilal, George E. $3 1263180
245 1 0 $a Antimicrobial activity of human leukocyte defensin HNP-4 against Gram-negative bacteria.
300 $a 61 p.
500 $a Adviser: Edwin L. Thomas.
500 $a Source: Masters Abstracts International, Volume: 46-05, page: 2638.
502 $a Thesis (M.D.S.)--The University of Tennessee Health Science Center, 2008.
520 $a Human neutrophils (PMN cells) contain four peptides known as alpha-defensins or HNP 1-4. The peptides have broad-spectrum antibiotic activity. HNP 1-3 are major neutrophil components. They differ by only one amino acid residue. HNP-4 is found in small amounts, and has a different sequence. HNP-4 purified from neutrophils was reported to be 100-times more active than HNP-1 against Escherichia coli, suggesting that HNP-4 plays a special role in helping neutrophils kill Gram-negative bacteria.
520 $a Activity of HNP-4 against Gram-negative bacteria is of special interest because Aggregatibacter (Actinobacillus) actinomycetemcomitans (A.a.) and other periodontal pathogens are Gram-negative. These bacteria are resistant to HNP 1-3. Defensin-resistance may contribute to the ability of these bacteria to cause disease. There have been no studies of HNP-4 activity against oral bacteria because HNP-4 is found in small amounts and is difficult to purify. Recently, HNP-4 was chemically synthesized, making it possible to study its antibacterial activity. Synthetic HNP-4 was reported to be no more active than HNP-1 against E. coli .
520 $a Lipopolysaccharide (LPS) covers the surface of Gram-negative bacteria. Each LPS molecule has three parts: a long carbohydrate chain (oligosaccharide) that is exposed on the cell surface, a short carbohydrate core, and lipid A that anchors LPS in the outer membrane. LPS on the bacterial cell surface may be the receptor for HNP-4 and other peptides that kill Gram-negative bacteria.
520 $a Our aims were to: (1) Compare the purity and physical properties of purified and synthetic HNP-4. (2) Compare activity of synthetic and purified HNP-4 against E. coli. (3) Determine whether HNP-4 binds to purified E. coli LPS. (4) Locate the HNP-4 binding site on E. coli LPS molecules. (5) Measure activity of HNP-4 against A.a. (6) Compare HNP-4 binding to LPS purified from E. coli and A.a.
520 $a Results: (1) Purified and synthetic HNP-4 were of high purity. They had the same molecular mass, which was equal to the mass calculated from the amino acid sequence. (2) Activity of purified and synthetic HNP-4 against E. coli was the same, and similar to the activity of HNP-1. (3) LPS purified from E. coli absorbed HNP-4. (4) Experiments with LPS fragments showed that HNP-4 was absorbed to the LPS inner core. (5) Synthetic HNP-4 partially inhibited growth of A.a. but did not kill these bacteria. (6) There was no difference in the ability of E. coli or A.a. LPS to absorb synthetic HNP-4.
520 $a The results suggest that HNP-4 is not more active than other neutrophil alpha-defensins against Gram-negative bacteria. The results also indicate that LPS on the surface of Gram-negative bacteria could be the receptor for HNP-4. Because HNP-4 binds to the LPS inner core, HNP-4 may help neutrophils kill Gram-negative bacteria that lack oligosaccharide and the LPS outer core.
520 $a The periodontal pathogen A.a. is resistant to all of the human leukocyte alpha-defensins including HNP-4. Therefore, synthetic HNP-4 is not likely to be used in dental practice to prevent or treat oral disease. Resistance of A.a. to HNP-4 is not the result of a difference in LPS structure that interferes with HNP-4 binding. Further studies are needed to determine the mechanism of defensin resistance.
590 $a School code: 0783.
650 4 $a Biology, Microbiology. $3 1017734
650 4 $a Health Sciences, Dentistry. $3 1019378
690 $a 0410
690 $a 0567
710 2 $a The University of Tennessee Health Science Center. $b Periodontology. $3 1263181
773 0 $t Masters Abstracts International $g 46-05.
790 $a 0783
790 1 0 $a Babu, Jegdish P. $e committee member
790 1 0 $a Bland, Paul S. $e committee member
790 1 0 $a Thomas, Edwin L., $e advisor
790 1 0 $a Tipton, David A. $e committee member
791 $a M.D.S.
792 $a 2008
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=1450495