Consequences of introducing a disulfide bond into an antibacterial and hemolytic peptide.

The effect of introducing a disulfide bridge between the N- and C-terminal ends on the structure and biological activities of the 13-residue linear peptide PKLLKTFLSKWIG(SPFK), which has both antibacterial and hemolytic activity, have been investigated. The terminal amino acids P and G in SPFK were replaced by cysteines to form a disulfide bridge. The linear peptides C(Acm)KLLKTFLSKWIC(Acm) and C(Acm) KLLKTFLSKWIC(Acm)-amide, where Acm is acetamidomethyl group, showed antibacterial activity but did not possess hemolytic activity unlike SPFK.

Interaction of antimicrobial peptides with biological and model membranes: structural and charge requirements for activity.

Species right across the evolutionary scale from insects to mammals use peptides as part of their host-defense system to counter microbial infection. The primary structures of a large number of these host-defense peptides have been determined. While there is no primary structure homology, the peptides are characterized by a preponderance of cationic and hydrophobic amino acids.

Studies on the relationship between structure and electrophoretic mobility of alpha-helical and beta-sheet peptides using capillary zone electrophoresis.

The electrophoretic behaviour of a series of 33 different synthetic peptides has been investigated using free solution high-performance capillary zonal electrophoretic (HPCZE) methods. The dependency of the electrophoretic mobility, mu(em), on the peptide charge, q, and on the charge-to-size ratio parameter, zeta, determined according to several electromobility models, have been examined. Significant divergences from linearity in the mu(em) vs.

Duodenal ulcer perforation: have H2 receptor blockers reduced mortality?

Elective surgery for peptic ulcer is becoming rare with the use of more effective medical therapy. However, life threatening complications have not reduced in number. A retrospective study was carried out to compare perforation rates per 10,000 admissions, mortality rates from perforated duodenal ulcers per 10,000 admission and the proportion of patients with perforated duodenal ulcer who died, before and after the introduction of H2 receptor blockers in a large teaching hospital in South India.

Surgical presentation of melioidosis in India.

Background: Melioidosis, the disease caused by Burkholderia pseudomallei, is common in Southeast Asia. It has also been reported from India, where some investigators feel it is under-diagnosed and under-reported. We report our experience with melioidosis presenting as abscesses at unusual sites.

Carcinoid tumor of common hepatic duct.

Primary carcinoid tumors of the biliary tract are extremely rare. We report a 36-year-old woman with recurrent acute cholangitis who was diagnosed to have a carcinoid in the common hepatic duct, with enlarged local nodes. She underwent local resection.

Biological activities of C-terminal 15-residue synthetic fragment of melittin: design of an analog with improved antibacterial activity.

Melittin, the 26-residue predominant toxic peptide from bee venom, exhibits potent antibacterial activity in addition to its hemolytic activity. The synthetic peptide of 15 residues corresponding to its C-terminal end (MCF), which encompasses its most amphiphilic segment, is now being shown to possess antibacterial activity about 5-7 times less compared to that of melittin. MCF, however, is 300 times less hemolytic.

Addition and omission analogs of the 13-residue antibacterial and hemolytic peptide PKLLKTFLSKWIG: structural preferences, model membrane binding and biological activities.

The consequences of selective addition or deletion of polar amino acids in a 13-residue antibacterial peptide PKLLKTFLSKWIG on structure, membrane binding and biological activities have been investigated. The variants generated are (a) S and T residues replaced by K, (b) S and T residues deleted individually and together, (c) introduction of two additional K and (d) deletion of L and L with T. In the aqueous environment all the peptides were unordered.

Diagnosis and management of gastrointestinal angiodysplasia.

Eighteen patients with gastrointestinal angiodysplasia were seen in a single surgical unit over a period of 8 years. The mean age at onset of symptoms was 33 years. The average duration of symptoms was 54 months (range 2 days-16 years).

Prokaryotic expression of bovine lactoferrin deletion mutants that bind to the Ca2+-dependent lactoferrin receptor on isolated rat hepatocytes.

We generated a series of recombinant variants of bovine lactoferrin (Lf) as fusion proteins using two prokaryotic expression vectors and examined the ability of the expressed proteins to compete with native Lf for binding to the Ca2+-dependent Lf receptor on isolated rat hepatocytes. A near-full-length bovine Lf cDNA (pN16b) was expressed in pGEMEX-2 as a gene 10 fusion protein (r-bLf10/-70). Deletions of pN16b were cloned into the HindIII/NotI and BamHI/NotI restriction sites of expression vector pET 32 and expressed as thioredoxin fusion proteins, r-bLfT/-271 and r-bLfT/-310, respectively.

Intraoperative enteroscopy in obscure gastrointestinal hemorrhage.

Forty three patients were diagnosed to have obscure gastrointestinal hemorrhage (OGH) between January 1987 and April 1996. Pre-operative diagnostic investigations were useful in localizing the site of bleeding in 28 patients (65.1%).

Structural features of helical aggregates of antibacterial peptides via simulated annealing and molecular modeling.

A 27-residue stretch of amino acids encompassing two putative 13-residue amphiphilic helical segments is an important determinant of activity in the 47-residue antibacterial peptide bovine seminalplasmin. Synthetic peptides corresponding to the 27-residue stretch (P27) SLSRYAKLANRLANPKLLETFLSKWIG as well as the 13-residue segments PKLLETFLSKWIG (SPF),exhibit antimicrobial activity. An analog of SPF where E has been replaced by K(SPFK) showed improved antimicrobial properties as compared to SPF.

Mechanism of antimicrobial action of indolicidin.

Indolicidin, a 13-residue antimicrobial peptide isolated from cytoplasmic granules of bovine neutrophils, exhibits activity against Gram-positive and Gram-negative bacteria as well as fungi. Although indolicidin is bactericidal and permeabilizes the bacterial membranes, it does not lyse the bacterial cells. We examined the effect of bactericidal concentrations of indolicidin on the morphology of Escherichia coli cells and found that it induces filamentation.

Isolated rat hepatocytes differentially bind and internalize bovine lactoferrin N- and C-lobes.

Isolated rat hepatocytes bind and internalize bovine lactoferrin (Lf) and its bound iron in a Ca2+-dependent manner. In this study, we determined if one or both halves of Lf (N- and C-lobes) were responsible for the interaction of Lf with hepatocytes. We isolated three tryptic fragments of bovine Lf.

Functional nucleotide excision repair is required for the preferential removal of N-ethylpurines from the transcribed strand of the dihydrofolate reductase gene of Chinese hamster ovary cells.

Transcription-coupled repair of DNA adducts is an essential factor that must be considered when one is elucidating biological endpoints resulting from exposure to genotoxic agents. Alkylating agents comprise one group of chemical compounds which modify DNA by reacting with oxygen and nitrogen atoms in the bases of the double helix. To discern the role of transcription-coupled DNA repair of N-ethylpurines present in discrete genetic domains, Chinese hamster ovary cells were exposed to N-ethyl-N-nitrosourea, and the clearance of the damage from the dihydrofolate reductase gene was investigated.

Identification of the region that plays an important role in determining antibacterial activity of bovine seminalplasmin.

Seminalplasmin (SPLN) is a 47-residue protein isolated from bovine seminal plasma having potent antimicrobial activity against a broad spectrum of microorganisms. SPLN, also known as caltrin, acts as a calcium transport regulator in bovine sperms. Analysis of the sequence of SPLN reveals a 27-residue stretch with the sequence SLSRYAKLANRLANPKLLETFLSKWIG more hydrophobic than the rest of the protein.

Requirements for antibacterial and hemolytic activities in the bovine neutrophil derived 13-residue peptide indolicidin.

The antimicrobial and hemolytic activities of the 13-residue peptide indolicidin (ILPWKWPWWPWRR-NH2), present in bovine neutrophils, and its analogs have been determined with a view to gaining insight into the structural roles of tryptophan and proline. Peptides where proline was replaced by alanine and tryptophan by phenylalanine showed antibacterial activities comparable to that of indolicidin. The peptides do not exhibit a strong propensity to occur in either helical or beta-sheet conformation.

Determination of delta 9-tetrahydrocannabinol levels in brain tissue using high-performance liquid chromatography with electrochemical detection.

delta 9-Tetrahydrocannabinol (delta 9-THC) is the major psychoactive component of cannabis. To assist in investigating the mechanism(s) of action of delta 9-THC, a convenient method for determining its levels in brain tissue is required. We now describe a method for determining nanogram quantities of delta 9-THC in rat brain tissue.

Nyctohemeral rhythm in the levels of S-adenosylmethionine in the rat pineal gland and its relationship to melatonin biosynthesis.

Liquid chromatographic techniques that permit the simultaneous analysis of S-adenosylmethionine, melatonin, and its intermediary metabolites N-acetyl-5-hydroxytryptamine and 5-hydroxytryptamine within individual pineal glands have been developed. S-Adenosylmethionine has been shown to undergo a marked nyctohemeral rhythm in the pineal gland of the rat, with maximal levels occurring during the light period and minimal levels during the dark period. Detailed studies of the temporal relationships between the levels of S-adenosylmethionine and those of melatonin and its intermediary metabolites suggest that an association exists between the levels of S-adenosylmethionine and the status of the biosynthesis of melatonin.

Structural and charge requirements for antimicrobial and hemolytic activity in the peptide PKLLETFLSKWIG, corresponding to the hydrophobic region of the antimicrobial protein bovine seminalplasmin.

Several analogs of the 13-residue antimicrobial and hemolytic peptide PKLLETFLSKWIG (SPF), which is the most hydrophobic region of the 47-residue antimicrobial protein seminalplasmin [Sitaram, N. & Nagaraj, R. (1990) J.