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Biomedical subjects

T Ganz

Publications and source records attributed to T Ganz.

At least 37 records · Page 2Linked to original sources
PubMed2001

An in vitro study of antibacterial properties of the cervical mucus plug in pregnancy.

OBJECTIVE: To evaluate whether cervical mucus plugs are antibacterial in vitro. STUDY DESIGN: Cervical mucus plugs from 56 healthy women in labor were studied by 2 different antimicrobial assays: (1) analysis of the inhibition by the cervical mucus plug of several gram-positive and gram-negative bacteria by overlaying the cervical mucus plug onto an agar plate with imbedded bacteria, and (2) determination of the antibacterial property of the cervical mucus plug material by radial diffusion assay with group B Streptococcus and Escherichia coli. RESULTS: In the agar overlay assay, there was complete inhibition of clinical isolates of Staphylococcus saprophyticus, E coli, and Pseudomonas aeruginosa and patient-variable partial-to-complete inhibition of Enterococcus faecium, Staphylococcus aureus, Streptococcus pyogenes, and Streptococcus agalactiae. In the radial diffusion assay, cervical mucus plugs had activity toward group B Streptococcus equivalent to 0.075 microg/mL of gentamicin and toward E coli equivalent to 0.5 microg/mL of gentamicin. CONCLUSION: A low-molecular substance with antibacterial activity in the cervical mucus plug may protect the fetus against ascending infections.

Anti-Bacterial Agents↗
PubMed2001

Effect of a collaborative weaning plan on patient outcome in the critical care setting.

OBJECTIVE: The process of weaning from mechanical ventilation can be complex, requiring collaborative care planning by members of the healthcare team. Improved outcomes have been demonstrated to result from collaborative decision-making processes (e.g., when ventilator teams were utilized). The purpose of this study was to evaluate the effect of a collaborative weaning plan (CWP) on length of time on mechanical ventilation, length of stay in the intensive care unit (ICU), and cost. DESIGN: A new, collaborative weaning plan in the form of a weaning board and flowsheet was introduced into a medical intensive care unit (MICU) setting. A pre- and post-quasi-experimental design using historical controls was used to test the hypotheses. Attempts to control for the effects of history were made by collecting data related to patient, staffing, and organizational variables that could independently effect outcome. SETTING: MICU in a west coast teaching hospital. PATIENTS: Critically ill patients receiving mechanical ventilation for 3 days or greater. INTERVENTION: Implementation of a collaborative weaning plan. MEASUREMENTS: Outcomes studied included length of stay in the MICU, length of time patients were mechanically ventilated in the MICU, cost per MICU stay, and the incidence of complications (e.g., reventilation, readmission to the ICU, and mortality rate). MAIN RESULTS: The CWP decreased length of stay in the MICU by 3.6 days (p =.03) and length of ventilator time by 2.7 days (p =.06). There were no significant differences between groups related to cost or incidence of complications. CONCLUSIONS: These results support the usefulness of collaborative structures (such as weaning boards/flowsheets) in decreasing ICU length of stay.

APACHE↗
PubMed2001

Determinants of Staphylococcus aureus nasal carriage.

Nasal carriage of Staphylococcus aureus has been identified as a risk factor for community-acquired and nosocomial infections. We screened 230 donors of diverse ethnic and socioeconomic backgrounds and identified 62 (27%) whose nasal secretions were colonized by S. aureus. In 18 donors in whom the various regions of the nasal luminal surface were separately sampled, the predominant region of S. aureus colonization was the moist squamous epithelium on the septum adjacent to the nasal ostium. Nasal fluid from carriers was defective in killing endogenous S. aureus and nasal carrier isolates of S. aureus but not a laboratory S. aureus strain. Transmission electron microscopy revealed that S. aureus isolates incubated in nasal fluid from carriers for 2 h at 37 degrees C were less damaged than those incubated in noncarrier fluid and were coated with an electron-dense layer. Compared with that from healthy donors and patients with acute rhinitis, nasal fluid from carriers contained elevated concentrations of the neutrophil-derived defensins human neutrophil peptides 1 to 3 (47- and 4-fold increases, respectively), indicative of a neutrophil-mediated inflammatory host response to S. aureus colonization. The concentration of the inducible epithelial antimicrobial peptide human beta-defensin 2 was also highly elevated compared to that in healthy donors, in whom the level was below the detection limit, or patients with acute rhinitis (sixfold increase). Thus, nasal carriage of S. aureus takes hold in nasal fluid that is permissive for colonization and induces a local inflammatory response that fails to clear the colonizing bacteria.

Body Fluids↗
PubMed2001

Direct and indirect bacterial killing functions of neutrophil defensins in lung explants.

Studies of the antimicrobial activity of neutrophil defensins have mostly been carried out in microbiological media, and their effects on the host defense in physiological conditions are unclear. We examined 1) the antibacterial activity of defensins in physiological media with and without lung tissue present, 2) the effect of defensins on hydrogen peroxide (H(2)O(2)) production by lung tissue that had been exposed to bacteria, and 3) the effect of diphenyleneiodonium (DPI), an inhibitor of reactive oxygen species formation, on the antibacterial activity of defensins in the presence of lung tissue. Defensins were incubated with Escherichia coli or Pseudomonas aeruginosa in the absence or presence of primary cultured mouse lung explants. Defensins reduced bacterial counts by approximately 65-fold and approximately 25-fold, respectively, at 48 h; bacterial counts were further decreased by approximately 600-fold and approximately 12,000-fold, respectively, in the presence of lung tissue. Defensins induced H(2)O(2) production by lung tissue, and the rate of killing of E. coli by defensins was reduced by approximately 2,500-fold in the presence of 10 microM DPI. We conclude that defensins exert a significant antimicrobial effect under physiological conditions and that this effect is enhanced in the presence of lung tissue by a mechanism that involves the production of reactive oxygen species.

Animals↗
PubMed2001

Therapeutic effect of a pig-derived peptide antibiotic on porcine wound infections.

PURPOSE: We investigated the therapeutic potential of the pig-derived antimicrobial peptide protegrin-1 (PG-1) against porcine skin wounds infected with Pseudomonas aeruginosa. MATERIALS AND METHODS: Using a porcine skin wound model, PG-1 was added to the wound fluid either at the time of P. aeruginosa inoculation, four hours after inoculation or 24 hours after inoculation. Wound fluids were analyzed 20-24 hours later by use of colony-forming unit (CFU) assays, semiquantitative immunoblot analysis for PG-1, and radial diffusion assays (RDA) for residual in vitro activity. RESULTS: Results of the CFU assays indicated a 10,000-fold decrease in the number of bacteria when PG-1 was added at the time of inoculation, a 120-fold decrease when added 4 hours after inoculation and a 10-fold decrease when added 24 hours after inoculation. Results of immunoblot analysis and RDA indicated that PG-1 concentrations for each of the three conditions remained increased in wound fluid 20 to 24 hours after treatment, and correlated with increased residual in vitro antimicrobial activity. CONCLUSIONS: These results document that the endogenous antibiotic PG-1 significantly prevented the colonization of P. aeruginosa in wounds and reduced the in vivo bacterial concentration in established wound infections. Therapeutics used in the same animal species from which they were derived are a promising means for preventing and treating localized infections.

Animals↗
PubMed2000

Granulysin, a T cell product, kills bacteria by altering membrane permeability.

Granulysin, a protein located in the acidic granules of human NK cells and cytotoxic T cells, has antimicrobial activity against a broad spectrum of microbial pathogens. A predicted model generated from the nuclear magnetic resonance structure of a related protein, NK lysin, suggested that granulysin contains a four alpha helical bundle motif, with the alpha helices enriched for positively charged amino acids, including arginine and lysine residues. Denaturation of the polypeptide reduced the alpha helical content from 49 to 18% resulted in complete inhibition of antimicrobial activity. Chemical modification of the arginine, but not the lysine, residues also blocked the antimicrobial activity and interfered with the ability of granulysin to adhere to Escherichia coli and Mycobacterium tuberculosis. Granulysin increased the permeability of bacterial membranes, as judged by its ability to allow access of cytosolic ss-galactosidase to its impermeant substrate. By electron microscopy, granulysin triggered fluid accumulation in the periplasm of M. tuberculosis, consistent with osmotic perturbation. These data suggest that the ability of granulysin to kill microbial pathogens is dependent on direct interaction with the microbial cell wall and/or membrane, leading to increased permeability and lysis.

Amino Acid Sequence↗
PubMed2000

Hepcidin, a urinary antimicrobial peptide synthesized in the liver.

Cysteine-rich antimicrobial peptides are abundant in animal and plant tissues involved in host defense. In insects, most are synthesized in the fat body, an organ analogous to the liver of vertebrates. From human urine, we characterized a cysteine-rich peptide with three forms differing by amino-terminal truncation, and we named it hepcidin (Hepc) because of its origin in the liver and its antimicrobial properties. Two predominant forms, Hepc20 and Hepc25, contained 20 and 25 amino acid residues with all 8 cysteines connected by intramolecular disulfide bonds. Reverse translation and search of the data bases found homologous liver cDNAs in species from fish to human and a corresponding human genomic sequence on human chromosome 19. The full cDNA by 5' rapid amplification of cDNA ends was 0.4 kilobase pair, in agreement with hepcidin mRNA size on Northern blots. The liver was the predominant site of mRNA expression. The encoded prepropeptide contains 84 amino acids, but only the 20-25-amino acid processed forms were found in urine. Hepcidins exhibited antifungal activity against Candida albicans, Aspergillus fumigatus, and Aspergillus niger and antibacterial activity against Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, and group B Streptococcus. Hepcidin may be a vertebrate counterpart of cysteine-rich antimicrobial peptides produced in the fat body of insects.

Amino Acid Sequence↗
PubMed2000

The alpha-defensins stimulate proteoglycan-dependent catabolism of low-density lipoprotein by vascular cells: a new class of inflammatory apolipoprotein and a possible contributor to atherogenesis.

Inflammation may contribute to the pathogenesis of atherosclerosis. On the basis of previous reports that human atherosclerotic lesions contain alpha-defensins, a class of cationic proteins released by activated neutrophils, the study was designed to ask whether defensins modulate the binding and catabolism of low-density lipoprotein (LDL) by human vascular cells. The results of the study demonstrated that defensin stimulated the binding of (125)I-LDL to cultured human umbilical vein endothelial cells, smooth muscle cells, and fibroblasts approximately 5-fold in a dose-dependent and saturable manner. Defensin and LDL formed stable complexes in solution and on cell surfaces. Stimulation of LDL binding by defensin was not inhibited by antibodies against the LDL-receptor (LDL-R), or by recombinant receptor-associated protein, which blocks binding of ligands to the alpha(2)-macroglobulin receptor/LDL-R-related protein and other LDL-R family members. Furthermore, defensin stimulated the binding, endocytosis, and degradation of LDL by fibroblasts lacking LDL-R. Stimulation of LDL degradation by defensin was inhibited approximately 75% by low concentrations of heparin (0.2 units/mL) and was similarly reduced in CHO cells lacking heparan-sulfate-containing proteoglycans. The effect of defensin was substantially increased in cells overexpressing the core protein of the syndecan-1 heparan sulfate proteoglycan. The alpha-defensins released from activated neutrophils may provide a link between inflammation and atherosclerosis by changing the pattern of LDL catabolism from LDL-R to the less efficient LDL-R-independent, proteoglycan-dependent pathway. (Blood. 2000;96:1393-1398)

Animals↗
PubMed2000

Microanalysis of antimicrobial properties of human fluids.

Host defense responses of animals and plants to pathogenic microbes are mediated in part by the release of antimicrobial substances into tissue fluids. Exploration of the antimicrobial properties of tissue fluids is often limited by their small quantity. We have developed assays of antimicrobial activity that require only 1 microl of fluid. Using normal nasal secretions as a model mucosal fluid we demonstrated that the kinetics of the 1 microl colony-forming unit (CFU) assays were equivalent to the larger CFU assays. The handling of viscous mucin-containing fluids was facilitated by pretreatment with N-acetylcysteine (NAC), a treatment that did not alter the performance of the assay. This low-volume assay will facilitate studies of the antimicrobial properties of scarce biological fluids.

Anti-Bacterial Agents↗
PubMed2000

Human beta defensin is absent in burn blister fluid.

Defensins are a family of cationic antimicrobial peptides that participate in innate host defence. Human beta defensin-2 (HBD-2) is produced by human keratinocytes, and has a potent bactericidal activity against a wide spectrum of microorganisms. We have recently shown that expression of HBD-2 is present in normal skin and lost in the full-thickness burn wound. Defensins have been found in the blister fluid of chronic wounds. Our study was designed to examine blister fluid from partial-thickness burns for defensin content. Fluid from five patients was collected from partial-thickness burn blisters, and then analysed by sandwich Enzyme-Linked Immunosorbent Assay (ELISA) with a monoclonal antibody and rabbit polyclonal antibody to HBD-2. The assay was validated against a Western blot assay for HBD-2 in samples of bronchoalveolar lavage fluid from patients with inflammatory lung disease. No HBD-2 was detectable in any of the burn blister fluids analysed. HBD-2 is lost in the full-thickness burn wound, and we have now demonstrated its absence in burn blister fluid. This finding represents evidence of a host defence defect within the burn wound and suggests a possible therapeutic role for antimicrobial peptides in the management of burn wounds.

Adolescent↗
PubMed2000

Regulation of human beta-defensins by gastric epithelial cells in response to infection with Helicobacter pylori or stimulation with interleukin-1.

Gastric epithelial cells in vitro and in vivo are shown to constitutively express the peptide antibiotic human beta-defensin type 1 (hBD-1). In contrast, hBD-2 expression is regulated in gastric epithelial cells and increases in response to infection with Helicobacter pylori or stimulation with the proinflammatory cytokine interleukin-1. These data suggest that hBD-2 is a component of the regulated host gastric epithelial cell response to H. pylori infection and proinflammatory mediators.

Defensins↗
PubMed2000

Beta-defensin expression in human mammary gland epithelia.

Milk of mammalian species contains a wide spectrum of anti-infectious factors, some of which are heat stable. Focusing on recently discovered heat-stable antibacterial peptides called defensins, which are expressed in epithelial tissues such as airway, skin, and kidney, we hypothesized that mammary gland epithelia produce and secrete defensins onto the epithelial surface and into milk. Using a reverse-transcription PCR assay, we identified the human beta-defensin-1 (hBD-1) gene transcript in a human mammary gland epithelial cell line, MCF-12A, and in mammary glandular tissue of nine nonlactating women. Epithelial cells harvested from milk of lactating women also expressed hBD-1 mRNA. Presence of hBD-1 peptide in mammary epithelia was confirmed by immunostaining with an hBD-1 antibody. In contrast, expression of human beta-defensin-2 was not apparent both at mRNA and protein levels. Our findings suggest a biologic role of hBD-1 in the human mammary gland.

Amino Acid Sequence↗
PubMed2000

Protegrins: new antibiotics of mammalian origin.

Protegrins and their derivatives are a new class of peptide antibiotics based on mammalian antimicrobial peptides. Their pharmacological properties include an unusually broad spectrum of antimicrobial activity against Gram-positive and Gram-negative bacteria, fungi and some enveloped viruses. Preclinical and clinical studies of the lead compound, IB-367, developed for topical applications, show promise for the prevention of chemotherapy- and radiation-induced oral mucositis.

Animals↗
PubMed2000

Human antimicrobial peptides: analysis and application.

Antimicrobial peptides are innate host defense molecules that have a direct effect on bacteria, fungi and enveloped viruses. They are found in evolutionarily diverse species ranging from prokaryotes and plants to invertebrate and vertebrate animals. Humans express several families of antimicrobial peptides in myeloid cells and on various epithelial surfaces where they are poised to defend against pathogens. Recently, antimicrobial peptides from animals and plants have served as templates for the design of new therapeutic antibiotics. This review provides an introduction to the biology of human antimicrobial peptides, followed by a more detailed discussion of their isolation from tissues and biological fluids, their purification by gel electrophoresis and chromatography and assays of their antimicrobial activities.

Anti-Bacterial Agents↗
PubMed1999

Expression and regulation of the human beta-defensins hBD-1 and hBD-2 in intestinal epithelium.

The intestinal epithelium forms a physical barrier to limit access of enteric microbes to the host and contributes to innate host defense by producing effector molecules against luminal microbes. To further define the role of the intestinal epithelium in antimicrobial host defense, we analyzed the expression, regulation, and production of two antimicrobial peptides, human defensins hBD-1 and hBD-2, by human intestinal epithelial cells in vitro and in vivo. The human colon epithelial cell lines HT-29 and Caco-2 constitutively express hBD-1 mRNA and protein but not hBD-2. However, hBD-2 expression is rapidly induced by IL-1alpha stimulation or infection of those cells with enteroinvasive bacteria. Moreover, hBD-2 functions as a NF-kappaB target gene in the intestinal epithelium as blocking NF-kappaB activation inhibits the up-regulated expression of hBD-2 in response to IL-1alpha stimulation or bacterial infection. Caco-2 cells produce two hBD-1 isoforms and a hBD-2 peptide larger in size than previously described hBD-2 isoforms. Paralleling the in vitro findings, human fetal intestinal xenografts constitutively express hBD-1, but not hBD-2, and hBD-2 expression, but not hBD-1, is up-regulated in xenografts infected intraluminally with Salmonella. hBD-1 is expressed by the epithelium of normal human colon and small intestine, with a similar pattern of expression in inflamed colon. In contrast, there is little hBD-2 expression by the epithelium of normal colon, but abundant hBD-2 expression by the epithelium of inflamed colon. hBD-1 and hBD-2 may be integral components of epithelial innate immunity in the intestine, with each occupying a distinct functional niche in intestinal mucosal defense.

Anti-Bacterial Agents↗