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A Boman

Publications and source records attributed to A Boman.

At least 37 records · Page 2Linked to original sources
PubMed1996

NK-lysin, structure and function of a novel effector molecule of porcine T and NK cells.

NK-lysin (NKL), a 78-residue antimicrobial peptide, was isolated from pig small intestine. Standard methods identified the peptide as basic, with six half-cystine residues in three intrachain disulphide bonds. The sequence showed 33% identity with a part of a putative gene product (NKG5) from activated T and NK cells, NK-lysin showed antibacterial activity against Escherichia coli and Bacillus megaterium and marked lytic activity against YAC-1, a NK sensitive tumour cell line, while sheep red blood cells were unaffected. The cDNA clone corresponding to NK-lysin has been characterized. We have also analyzed the cell and tissue specific expression and the induction of the gene. A lymphocyte fraction enriched in T and NK cells, stimulated by human interleukin-2 (IL-2), showed a 30-fold increase of the NKL transcript. NK-lysin specific mRNA is also detectable in spleen, bone marrow and colon. Immunostaining showed NKL to be present in different types of lymphocytes. Our results strongly suggest that NK-lysin is involved in the inducible cytotoxicity of T and NK cells.

Animals↗
PubMed1995

Interaction of the mammalian antibacterial peptide cecropin P1 with phospholipid vesicles.

Cecropins are positively charged antibacterial polypeptides that were originally isolated from insects. Later on a mammalian homologue, cecropin P1 (CecP), was isolated from pig intestines. While insect cecropins are highly potent against both Gram-negative and Gram-positive bacteria, CecP is as active as insect cecropins against Gram-negative but has reduced activity against Gram-positive bacteria. To gain insight into the mechanism of action of CecP and the molecular basis of its antibacterial specificity, the peptide and its proline incorporated analogue (at the conserved position found in insect cecropins), P22-CecP, were synthesized and labeled on their N-terminal amino-acids with fluorescent probes, without significantly affecting their antibacterial activities. Fluorescence studies indicated that the N-terminal of CecP is located on the surface of phospholipid membranes. Binding experiments revealed that CecP binds acidic phosphatidylserine/phosphatidylcholine (PS/PC) vesicles better than zwitterionic PC vesicles, which correlates with its ability to permeate the former better than the latter. The shape of the binding isotherms suggest that CecP, like insect cecropin, binds phospholipids in a simple, noncooperative manner. However, resonance energy transfer (RET) measurements revealed that, unlike insect cecropins, CecP does not aggregate in the membrane even at relatively high peptide to lipid ratios. The stoichiometry of CecP binding to vesicles suggests that amount of CecP sufficient to form a monolayer causes vesicle permeation. In spite of the incorporation of the conserved proline in P22-CecP, the analogue has reduced antibacterial activity, which correlates with its reduced alpha-helical structure and its lower partitioning and membrane permeating activity with phospholipid vesicles. Taken together, our results support a mechanism in which CecP disrupts the structure of the bacterial membrane by (i) binding of peptide monomers to the acidic surface of the bacterial membrane and (ii) disintegrating the bacterial membrane by disrupting the lipid packing in the bilayers. These results, combined with data reported for other antibacterial polypeptides, suggest that the organization of peptide monomers within phospholipid membranes contributes to Gram-positive/Gram-negative antibacterial specificity.

Amino Acid Sequence↗
PubMed1995

NK-lysin, a novel effector peptide of cytotoxic T and NK cells. Structure and cDNA cloning of the porcine form, induction by interleukin 2, antibacterial and antitumour activity.

A 78 residue antimicrobial, basic peptide, NK-lysin, with three intrachain disulfide bonds was purified from pig small intestine and characterized. A corresponding clone was isolated from a porcine bone marrow cDNA library. The 780 bp DNA sequence had a reading frame of 129 amino acids which corresponded to NK-lysin. The clone was used to show that stimulation with human interleukin-2 induced synthesis of NK-lysin-specific mRNA in a lymphocyte fraction enriched for T and NK cells. Lower levels of mRNA were detected in tissues known to contain T and NK cells, such as small intestine, spleen and colon. Interleukin-2 also induced both proliferation of the lymphocyte fraction and cytolytic function in these cells. Immunostaining showed that NK-lysin was present in cells positive for CD8, CD2 and CD4. NK-lysin showed high anti-bacterial activity against Escherichia coli and Bacillus megaterium and moderate activity against Acinetobacter calcoaceticus and Streptococcus pyogenes. The peptide showed a marked lytic activity against an NK-sensitive mouse tumour cell line, YAC-1, but it did not lyse red blood cells. The amino acid sequence of NK-lysin exhibits 33% identity with a putative human preproprotein, NKG5, of unknown function but derived from a cDNA clone of activated NK cells. We suggest that NK-lysin is a new effector molecule of cytotoxic T and NK cells.

Amino Acid Sequence↗
PubMed1995

Retro and retroenantio analogs of cecropin-melittin hybrids.

Hybrid analogs of cecropin A (CA) and melittin (M), which are potent antibacterial peptides, have been synthesized. To understand the structural requirements for this antibacterial activity, we have also synthesized the enantio, retro, and retroenantio isomers of two of the hybrids and their N-terminally acetylated derivatives. All analogs of CA(1-13)M(1-13)-NH2 were as active as the parent peptide against five test bacterial strains, but one bacterial strain was resistant to the retro and retroenantio derivatives. Similarly, all analogs of CA(1-7)M(2-9)-NH2 were active against four strains, while two strains were resistant to the retro and retroenantio analogs containing free NH3+ end groups, but acetylation restored activity against one of them. From these data it was concluded that chirality of the peptide was not a critical feature, and full activity could be achieved with peptides containing either all L- or all D-amino acids in their respective right-handed or left-handed helical conformations. For most of the bacterial strains, the sequence of these peptides or the direction of the peptide bonds could be critical but not both at the same time. For some strains, both needed to be conserved.

Amino Acid Sequence↗
PubMed1995

Percutaneous absorption of organic solvents during intermittent exposure in guinea pigs.

Skin absorption under intermittent exposure of guinea pigs to n-butanol, toluene, 1,1,1-trichloroethane was studied. Groups of guinea pigs were exposed to test organic solvents for 1 min at 30-min intervals during 4 h, in all 8 exposures. Skin absorption of solvent was assessed by following the concentration of solvent in the blood. This intermittent exposure was compared to continuous exposure over 4 h. Absorption of toluene and 1,1,1-trichloroethane was low, but a considerable amount of butanol was absorbed through the skin on intermittent exposure. A typical serrated absorption profile was seen for butanol that was less pronounced for toluene and 1,1,1-trichloroethane. The absorption of butanol was highest at the end of the exposure period. The differences in absorption profiles may be due to the differences in vapour pressure in the solvents in association with the animal method used. The amount absorbed varied inversely with vapour pressure. Hair stubble may act as a trap for solvents with low vapour pressure. Adequate ventilation reduces unoccluded skin absorption of volatile organic solvents.

1-Butanol↗
PubMed1994

Experience with the murine local lymph node assay: inability to discriminate between allergens and irritants.

The murine local lymph node assay is a new predictive test for identifying contact sensitizers. It measures the proliferative response in the lymph nodes during the sensitization phase. In the present study, moderate-to-extreme allergens (from human and guinea pig experience) gave clearly positive results in this assay. However, irritants tested, i.e. sodium dodecyl sulphate (SDS), chloroform/methanol, oxalic acid, triton X-100 and methylsalicylate, also gave positive results, not distinguishable from the results with low-grade/moderate allergens. Two allergens were also tested in the presence of 10% SDS. The effect on proliferation was additive in the first case and synergistic in the second. The local lymph node assay in its present design and with the criteria used for a positive response requires further validation studies and perhaps further development before it can be accepted as an alternative to guinea pig tests for allergenicity. Substances with exclusively irritating properties could falsely be classified as allergens by the method or, alternatively, the allergenicity of chemicals with both allergenic and irritating properties could be overestimated.

Allergens↗
PubMed1993

Isolation of three antibacterial peptides from pig intestine: gastric inhibitory polypeptide (7-42), diazepam-binding inhibitor (32-86) and a novel factor, peptide 3910.

Two antibacterial peptides, cecropin P1 and PR-39 (39-residue proline/arginine-rich peptide), from the upper part of pig small intestine have previously been isolated and characterized. We have now continued our search for antibacterial peptides in different side fractions generated during the isolation of intestinal hormones. Starting from one such fraction and monitoring activity against Bacillus megaterium, we isolated three homogeneous peptides by three consecutive chromatographic steps. Amino acid sequence analysis in combination with mass spectrometry identified two of the peptides as gastric inhibitory polypeptide (7-42) [GIP(7-42)] and diazepam-binding inhibitor (32-86) [DBI(32-86)], derived from factors already known. However, intact GIP and DBI have hardly any antibacterial activity by themselves. The third peptide constitutes a previously unknown structure, designated as peptide 3910 from its molecular mass. All three peptides showed good activity against B. megaterium. In addition, GIP (7-42) showed some activity against Streptococcus pyogenes and an Escherichia coli mutant with a defect in its outer membrane.

Amino Acid Sequence↗
PubMed1993

Mechanisms of action on Escherichia coli of cecropin P1 and PR-39, two antibacterial peptides from pig intestine.

Cecropin P1 and PR-39 are two antibacterial peptides isolated from the upper part of the small intestine of the pig. They have been sequenced, and their antibacterial spectra have been investigated (J.-Y. Lee, A. Boman, C. Sun, M. Andersson, H. Jörnvall, V. Mutt, and H. G. Boman, Proc. Natl. Acad. Sci. USA 86:9159-9162, 1989; B. Agerberth, J.-Y. Lee, T. Bergman, M. Carlquist, H. G. Boman, V. Mutt, and H. Jörnvall, Eur. J. Biochem. 202:849-854, 1991). We have now compared these two peptides for their mechanism of action on Escherichia coli K-12 by using three strains with different markers. Our results show that cecropin P1, like other cecropins, kills bacteria by lysis and that this reaction requires more peptide to kill more cells. PR-39 requires a lag period of about 8 min to penetrate the outer membrane of wild-type E. coli; then killing is quite fast. This lag period was absent in the envA1 mutant; in this strain the outer membrane was freely permeable to both peptides. PR-39 killed growing bacteria faster than nongrowing cells; for cecropin P1 there was no such difference. It is suggested from isotope incorporation experiments that PR-39 kills bacteria by a mechanism that stops protein and DNA synthesis and results in degradation of these components.

Animals↗
PubMed1993

Inhalation of cobalt by sensitised guinea pigs: effects on the lungs.

Two groups, each of six guinea pigs, were sensitised by the application of cobalt chloride (CoCl2) on the skin on day 0, 2, 7, and 9 and the establishment of contact allergy was confirmed by patch testing on day 21. A further six animals were not sensitised. Starting on day 42 one sensitised group and the non-sensitised group were exposed by inhalation to 2.4 (0.8) mg (mean (SD)) Co in the form of CoCl2 for six hours a day for two weeks. After exposure the lungs were lavaged and the cells obtained were studied by light and electron microscopy. In the sensitised exposed group much more lavage liquid was retained in the lungs than in the other two groups; although more liquid was instilled in the lungs of this group, on average only 5 (range 2.5-10) ml were recovered compared with 10 ml in all animals in the other two groups. In the sensitised exposed group, the percentage of neutrophils and eosinophils tended to be higher than in the non-sensitised exposed group. The results indicate that the lungs of guinea pigs allergic to contact with Co react differently to inhaled Co compared with those of non-sensitised ones.

Administration, Inhalation↗
PubMed1992

Shortened cecropin A-melittin hybrids. Significant size reduction retains potent antibiotic activity.

We have earlier reported two 26-residue antibacterial peptides made up from different segments of cecropin A (CA) and melittin (M). We now report a substantial reduction in size at the C-terminal section of the highly active hybrid CA(1-8)M(1-18), leading to a series of 20-, 18- and 15-residue analogs with antibiotic properties similar to the larger molecule. In particular, the 15-residue hybrids CA(1-7)M(2-9), CA(1-7)M(4-11) and CA(1-7)M(5-12) are the shortest cecropin-based peptide antibiotics described so far, with antibacterial activity and spectra similar or better than cecropin A and a 60% reduction in size. Their reduced size and highly alpha-helical structure require an alternative mechanism for their interaction with bacterial membranes.

Amino Acid Sequence↗
PubMed1992

Antibacterial peptides designed as analogs or hybrids of cecropins and melittin.

Eight new analogs of cecropin A, two new analogs of melittin and 30 hybrid peptides containing sequences from cecropins and melittin have been synthesized. The lengths of the peptides have varied from 37 residues (the length of cecropin A) to 18 residues. The peptides have been assayed for lysis of sheep red blood cells and for antibacterial activity against two Gram negative and three Gram positive bacteria. The best analogs of cecropin A maintained the anti-Escherichia coli activity of the parental peptide, and were not lytic for red blood cells. Melittin and its replacement analogs were all lytic for red blood cells, but an analog with transposed segments was not. Several of the hybrid peptides were found to be both non-hemolytic and highly active against all test bacteria. The data were used to define the structural requirements for antibacterial activity.

Amino Acid Sequence↗
PubMed1992

Permeation and destructive effects of disinfectants on protective gloves.

In working situations where there is a possibility of acquiring blood-borne infections, the use of disinfectants is important. It is also important to use protective gloves, both to protect the skin against disinfectants and to protect against infections. Changes in the structure of the glove material may, however, interfere with the protective capability of the gloves. The influence of 4 disinfectants on the material structure and protective effect of 6 different brands of protective gloves was studied. The proposed International Organization for Standardization (ISO) standard method for determining the liquid chemical resistance of air-impermeable materials was used for permeation testing. Pieces of latex and vinyl glove were also exposed to isopropanol and ethanol for 10, 30 and 60 min and then viewed in a scanning electron microscope. Isopropanol permeated through latex and vinyl gloves in less than 10 min. The polyethylene (PE) gloves were of quite variable quality, and the breakthrough time ranged from 4 to greater than 240 min. The latex and vinyl gloves were also permeated by ethanol, but at a much lower rate. The disinfectants Blifacid, based on p-chloro-m-cresol, and Cidex, based on glutaraldehyde, did not permeate any of the gloves tested within 60 min. Isopropanol had a destructive effect on the material, which became opaque, stiff and brittle. This change in structure was verified with the scanning electron microscope. The tested gloves of latex, vinyl and PE, gave acceptable protection from contact with Blifacid and Cidex for at least 60 min. The same gloves do not give any total protection from contact with isopropanol and ethanol.

Disinfectants↗