Presence Of Lf Research Articles

Self-Responsive Fluorescence Aptasensor for Lactoferrin Determination in Dairy Products.

In this study, a self-responsive fluorescence aptasensor was established for the determination of lactoferrin (Lf) in dairy products. Herein, the aptamer itself functions as both a recognition element that specifically binds to Lf and a fluorescent signal reporter in conjunction with fluorescent moiety. In the presence of Lf, the aptamer preferentially binds to Lf due to its specific and high-affinity recognition by folding into a self-assembled and three-dimensional spatial structure. Meanwhile, its reduced spatial distance in the aptamer-Lf complex induces a FRET phenomenon based on the quenching of 6-FAM by amino acids in the Lf protein, resulting in a turn-off of the fluorescence of the system. As a result, the Lf concentration can be determined straightforwardly corresponding to the change in the self-responsive fluorescence signal. Under the optimized conditions, good linearities (R2 > 0.99) were achieved in an Lf concentration range of 2~10 μg/mL for both standard solutions and the spiked matrix, as well as with the desirable detection limits of 0.68 μg/mL and 0.46 μg/mL, respectively. Moreover, the fluorescence aptasensor exhibited reliable recoveries (89.5-104.3%) in terms of detecting Lf in three commercial samples, which is comparable to the accuracy of the HPCE method. The fluorescence aptasensor offers a user-friendly, cost-efficient, and promising sensor platform for point-of-need detection.

Sperm functionality is differentially regulated by porcine oviductal extracellular vesicles from the distinct phases of the estrous cycle.

Context Extracellular vesicles (EVs) derived from the oviductal fluid (oEVs) play a critical role in various reproductive processes, including sperm capacitation, fertilisation, and early embryo development. Aims To characterise porcine oEVs (poEVs) from different stages of the estrous cycle (late follicular, LF; early luteal, EL; mid luteal, ML; late luteal, LL) and investigate their impact on sperm functionality. Methods poEVs were isolated, characterised, and labelled to assess their binding to boar spermatozoa. The effects of poEVs on sperm motility, viability, acrosomal status, protein kinase A phosphorylation (pPKAs), tyrosine phosphorylation (Tyr-P), and in in vitro fertility were analysed. Key results poEVs were observed as round or cup-shaped membrane-surrounded vesicles. Statistical analysis showed that poEVs did not significantly differ in size, quantity, or protein concentration among phases of the estrous cycle. However, LF poEVs demonstrated a higher affinity for binding to sperm. Treatment with EL, ML, and LL poEVs resulted in a decrease in sperm progressive motility and total motility. Moreover, pPKA levels were reduced in presence of LF, EL, and ML poEVs, while Tyr-P levels did not differ between groups. LF poEVs also reduced sperm penetration rate and the number of spermatozoa per penetrated oocyte (P Conclusions poEVs from different stages of the estrous cycle play a modulatory role in sperm functionality by interacting with spermatozoa, affecting motility and capacitation, and participating in sperm-oocyte interaction. Implications The differential effects of LF and LL poEVs suggest the potential use of poEVs as additives in IVF systems to regulate sperm-oocyte interaction.

Baseline Interleukin-6 as a Preoperative Biomarker for Liver Fibrosis

Introduction: Liver (hepatic) fibrosis (LF) is characterized by impaired function and regenerative capacity of the liver and can lead to significantly increased morbidity and mortality in the context of surgical liver resection (LR). For this reason, it is crucial to identify the extent of LF preoperatively. Interleukin-6 (IL-6) is known to play a key role in the pathogenesis of LF, but its exact value as a preoperative marker is unknown. This study aimed to investigate the correlation between preoperatively determined IL-6 and the presence of LF. Methods: In this prospective study, IL-6 was determined in 134 consecutive patients undergoing LR. Patients with liver cirrhosis (LC) and patients with clinical or laboratory signs of inflammation were excluded. LF was graded by a blinded pathologist with regard to the degree of LF according to the Desmet classification (0–4). Baseline IL-6 and degree of LF were correlated. Results: A total of 134 patients were prospectively included prior to LR. For 104 patients, LF was graded and inflammatory parameters were available. Thirty-five of these patients showed LC (Desmet 4), and another 33 patients showed preoperatively elevated inflammatory markers. Two of the remaining patients were liver transplant patients. These patients were excluded from the final analysis. According to Desmet, the remaining 34 patients had LF grade 0 or 1 (none or minimal LF) in 26 cases and LF grade 2 or 3 (moderate-to-severe LF) in 8 cases. Correlation of LF with preoperatively determined IL-6 yielded significantly higher IL-6 levels in the group of patients with moderate-to-severe LF (Desmet 2 or 3) compared to the group with none or minimal LF (Desmet 0 or 1; p = 0.0495). Conclusion: In the context of LR, our results showed a correlation of preoperatively determined IL-6 with the extent of LF present. Higher serum baseline IL-6 concentrations were associated with a higher degree of LF, whereas no other blood parameter or score was that predictive for LF. Our results suggest that baseline IL-6 might serve as a valuable parameter to assess LF prior to LR. More patients need to be analyzed to further evaluate and confirm the predictive accuracy of IL-6 for LF.

Multifunctional Titanium Surfaces for Orthopedic Implants: Antimicrobial Activity and Enhanced Osseointegration.

The use of implants in orthopedics and dental practice is a widespread surgical procedure to treat diverse diseases. However, peri-implantitis due to infections and/or poor osseointegration can lead to metallic implant failure. The aim of this study was to develop a multifunctional coating on titanium (Ti) surfaces, to simultaneously deal with both issues, by combining antibacterial silver nanoparticles (AgNPs) and regenerative properties of lactoferrin (Lf). A simple and cost-effective methodology that allows the direct multifunctionalization of Ti surfaces was developed. The modified surfaces were characterized by atomic force microscopy (AFM), X-ray photoelectron spectroscopy, and contact angle measurements. Additionally, in vitro preosteoblast cell adhesion, cell viability, and differentiation were evaluated. The antibacterial capability of the surfaces was tested against Staphylococcus aureus as a prosthesis infection model strain. Our results showed that Lf adsorbed on both Ti surfaces and Ti surfaces with adsorbed AgNPs. Simultaneously, the presence of Lf and AgNPs notably improved preosteoblast adhesion, proliferation, and differentiation, whereas it reduced the bacterial colonization by 97.7%. Our findings indicate that this simple method may have potential applications in medical devices to both improve osseointegration and reduce bacterial infection risk, enhancing successful implantation and patients' quality of life.

Prolactin Receptor (PRLR) Isoform Expression in the Murine Oviduct

The most common and most deadly form of “ovarian”cancer is High-Grade Serous Carcinoma (HGSC), now appreciated to arise from epithelial cells of the fallopian tube/oviduct. The serum analyte with the greatest specificity and sensitivity that correlates with the presence or absence of HGSC is prolactin (PRL). However, unknown is whether elevated PRL initiates disease or is the result of disease, although once cancer is present,it is clear that PRL promotes disease. In order to examine the potential for disease initiation in normal animals, it was first important to determine which cells in the mouse oviduct respond to PRL. In many cell types, the long form of the Prlr mediates increased survival, proliferation and migration, whereas the short forms have the opposite effect. After establishing equivalent efficiencies of primers for the long form (LF) and 3 short forms (SF1-3) of the murine Prlr and the endogenous control gene, Gapdh, the mRNA expression profiles of these forms of the receptor were followed by RT-qPCR as a function of stage of the estrous cycle (proestrus, estrus, metestrus, diestrus - determined by vaginal cytology) and region of the oviduct (isthmus, ampulla and fimbria). Expression of SF1 was not detected. SF2 was essentially consistently expressed throughout the oviduct and at all stages of the estrous cycle. By contrast, the ratio of LF to SF3 varied by region of the tube, with more SF3 towards the fimbria and more LF towards the isthmus. The epithelium of the oviduct is primarily composed of multi-ciliated cells and secretory cells, with more ciliated cells towards the fimbria and more secretory cells towards the isthmus. The RT-qPCR results therefore suggested the possibility that a greater proportion of LF Prlr was present on secretory cells and a greater proportion of SF3 Prlr on ciliated cells. Using antibodies raised against intracellular peptide regions specificto the LF (aa 309-325) and SF3 (aa 281-296), both receptor isoforms were localized by immunofluorescence to apical regions of both epithelial cell types,but the presence of receptors on cilia (clearly demonstrated by 3Dreconstruction and rotation) complicated analysis of relative fluorescence by microscopy. Only the LF Prlr signals via Stat5 and so it was anticipated thatStat5 activation could serve as a substitute marker of the relative presence ofLF Prlr. Following in vivo intraperitoneal injection of PRL (5μg/g, 30 min),activated Stat5 was localized to epithelial cells at the base of, and in between, mucosal folds, thereby suggesting a further regionality to receptor distribution. For the fimbrial region only, which is where HGSC is thought to arise, expression of both the LF and SF3 Prlr changed as a function of the stage of the estrous cycle, with highest mRNA expression at diestrus/proestrus. Ongoing work includes flow cytometry of epithelial subpopulations and spatialanalysis of gene expression.

Three dimensional structure of the anthrax toxin translocon–lethal factor complex by cryo‐electron microscopy

We have visualized by cryo-electron microscopy (cryo-EM) the complex of the anthrax protective antigen (PA) translocon and the N-terminal domain of anthrax lethal factor (LF(N) inserted into a nanodisc model lipid bilayer. We have determined the structure of this complex at a nominal resolution of 16 Å by single-particle analysis and three-dimensional reconstruction. Consistent with our previous analysis of negatively stained unliganded PA, the translocon comprises a globular structure (cap) separated from the nanodisc bilayer by a narrow stalk that terminates in a transmembrane channel (incompletely distinguished in this reconstruction). The globular cap is larger than the unliganded PA pore, probably due to distortions introduced in the previous negatively stained structures. The cap exhibits larger, more distinct radial protrusions, previously identified with PA domain three, fitted by elements of the NMFF PA prepore crystal structure. The presence of LF(N), though not distinguished due to the seven-fold averaging used in the reconstruction, contributes to the distinct protrusions on the cap rim volume distal to the membrane. Furthermore, the lumen of the cap region is less resolved than the unliganded negatively stained PA, due to the low contrast obtained in our images of this specimen. Presence of the LF(N) extended helix and N terminal unstructured regions may also contribute to this additional internal density within the interior of the cap. Initial NMFF fitting of the cryoEM-defined PA pore cap region positions the Phe clamp region of the PA pore translocon directly above an internal vestibule, consistent with its role in toxin translocation.

Effect of bovine lactoferrin on the minimum inhibitory concentrations of ampicillin and trimethoprim–sulfamethoxazole for clinical Shigella spp. strains1This article is part of a Special Issue entitled Lactoferrin and has undergone the Journal’s usual peer review process.

Here, we determined the effect of bovine lactoferrin (bLF) on the minimum inhibitory concentration (MIC) of ampicillin and trimethoprim–sulfamethoxazole in Shigella . Using a microdilution method, the MIC was determined in the presence or absence of bovine lactoferrin (10 mg/mL) on 88 Shigella strains (56 Shigella flexneri , 15 Shigella boydii , 13 Shigella sonnei , and 4 Shigella dysenteriae ) previously isolated from peruvian children <2 years old. A fold change of 2 or more in MIC values was considered significant. For ampicillin, 67 (76%) strains were highly resistant; one-third of the strains (32%) showed a decrease in ampicillin MIC in the presence of LF. This was more typical of MIC values in less resistant strains. For 7 (8%) ampicillin-resistant strains, the decrease in the MIC resulted in the strains reaching the cutoff for susceptible in the presence of bLF. For trimethoprim–sulfamethoxazole, 93% of the isolates (n = 82) were highly resistant and only 4 isolates (5%) decreased their MIC in the presence of bLF. None of the trimethoprim–sulfamethoxazole resistant strains became susceptible in the presence of LF. The decrease in the MIC in the presence of bLF seems to depend on the mechanisms of action of each antibiotic. In vivo studies are needed to further evaluate bLF as a coadjuvant to antibiotic treatment of resistant Shigella.

The effect of lactoferrin on oral bacterial attachment

Lactoferrin (Lf), an iron-binding salivary glycoprotein, plays an important role in human innate defense against local mucosal infection. We hypothesized that Lf interferes with initial oral bacterial attachment to surfaces by iron sequestration, so inhibiting subsequent biofilm formation. The objective was to investigate the effect of Lf on the early stages of single-species and multi-species oral biofilm development. Streptococcus gordonii, Streptococcus mutans, Fusobacterium nucleatum and Porphyromonas gingivalis were used in this study. Glass disks of a two-track flow cell coated with flowing artificial saliva (0.3 ml/min) with and without Lf (100 microg/ml) were used for studying bacterial attachment (3 h, 37 degrees C). Attachment was also examined by incubating single or multiple species of test bacteria (10(7) colony-forming units/ml) with Lf-coated (20-100 microg/ml) and uncoated glass slides. The effects of beta-lactoglobulin, 2,2'-dipyridyl (25-100 microg/ml), an iron chelator, and FeCl3 on attachment were also examined. Lf inhibited the initial attachment of S. gordonii (50.3%, P < 0.05) but not that of F. nucleatum and P. gingivalis. However, the attachment of a dual-species biofilm containing S. gordonii (i.e. S. gordonii/F. nucleatum or S. gordonii/P. gingivalis) was significantly reduced (48.7% or 62.1%, respectively, P < 0.05) in the presence of Lf. beta-Lactoglobulin did not affect the attachment of S. gordonii. In the presence of 100 microm 2,2'-dipyridyl, attachment of S. gordonii was reduced by 53.87%. No reduction in attachment was noted in S. gordonii pretreated with Lf (100 microg/ml) and FeCl3 (20-200 microm). Lf suppresses initial attachment of S. gordonii and S. gordonii coaggregates by iron sequestration. This may lead to subsequent inhibition of oral biofilm development.

Effect of lactoferrin on oxidative features of ceruloplasmin

In our previous report we first described a complex between lactoferrin (Lf) and ceruloplasmin (Cp) with K (d) approximately 1.8 microM. The presence of this complex in colostrum that never contains more than 0.3 microM Cp questions the reliability of K (d) value. We carefully studied Lf binding to Cp and investigated the enzymatic activity of the latter in the presence of Lf, which allowed obtaining a new value for K (d) of Cp-Lf complex. Lf interacting with Cp changes its oxidizing activity with various substrates, such as Fe(2+), o-dianisidine (o-DA), p-phenylenediamine (p-PD) and dihydroxyphenylalanine (DOPA). The presence of at least two binding sites for Lf in Cp molecule is deduced from comparison of substrates' oxidation kinetics with and without Lf. When Lf binds to the first site affinity of Cp to Fe(2+) and to o-DA increases, but it decreases towards DOPA and remains unchanged towards p-PD. Oxidation rate of Fe(2+) grows, while that of o-DA, p-PD and DOPA goes down. Subsequent Lf binding to the second center has no effect on iron oxidation, hampers DOPA and o-DA oxidation, and reduces affinity towards p-PD. Scatchard plot for Lf sorbing to Cp-Sepharose allowed estimating K (d) for Lf binding to high-affinity (approximately 13.4 nM) and low-affinity (approximately 211 nM) sites. The observed effect of Lf on ferroxidase activity of Cp is likely to have physiological implications.

Utilization of lactoferrin to fight antibiotic-resistant mammary gland pathogens1,2

The widespread use of antibiotics has lead to the increased presence of pathogens that are less susceptible to their antibacterial effect. Lactoferrin (Lf) is naturally produced by the mammary gland. Lactoferrin is the main whey protein in human milk and is also present in cow's milk but at a much lower concentration than in human milk. This protein appears to have many biological functions, including antibacterial and antiinflammatory activities. The best-known effect of Lf is to bind iron that is essential for bacterial growth. However, the cationic nature of this protein also appears to be important for the antimicrobial activity of this protein. Lactoferrin has a weak antibacterial effect when used alone, but interestingly, Lf appears much more effective when used at low concentration in combination with several antibiotics. The most striking observation is that Lf increases the inhibitory activity of penicillin up to 4-fold in most penicillin-susceptible Staphylococcus aureus strains, whereas this increase was 4- to 16-fold in penicillin-resistant strains. Indeed, Lf reduces beta-lactamase activity in S. aureus strains producing this enzyme. Transcription of beta-lactamase gene is dramatically repressed in the presence of Lf. We evaluated the efficacy of intramammary treatments containing penicillin G or bovine Lf (bLf), or both, to cure chronic mastitis caused by a clinical isolate of S. aureus highly resistant to beta-lactam antibiotics. In a first trial, mastitis was induced in lactating cows by injecting a low dose of S. aureus through the teat canal of all quarters. Bacterial cure rate was null for control quarters, 11.1% for bLf, 9.1% for penicillin, and 45.5% for the combination of bLf and penicillin. A second trial was undertaken to investigate the effect of an extended therapy on chronic mastitis acquired in a previous lactation. Quarters were treated with 100,000 IU of penicillin G with or without 250 mg of bLf for 7 d. Bacterial cure rate was greater for the bLf + penicillin combination (33.3%) compared with penicillin alone (12.5%). In conclusion, bLf added to penicillin is an effective combination for the treatment of stable S. aureus infections resistant to beta-lactam antibiotics.

Induction of Regulatory T Cells by Leflunomide in a Murine Model of Contact Allergen Sensitivity

Allergic contact dermatitis and contact hypersensitivity (CHS) are characterized by allergen-specific activation of CD8+ and CD4+ T cells and the production of cytokines resulting in an inflammatory response and tissue damage. We show here that the immunosuppressive compound leflunomide (N-[4-trifluoro-methylphenyl]-5-methylisoxazol-4 carboxamide, HWA 486) (LF) inhibited the contact allergic response induced in mice by epicutaneous application of the haptens dinitrofluorobenzene (DNFB) and oxazolone. The extent of ear swelling remained significantly reduced following repeated challenge with DNFB for up to 18 weeks. LF and DNFB had to be applied simultaneously for inhibition to occur. The loss of CHS responses was shown to be antigen-specific. Adoptive transfer of leukocytes from LF-treated mice into naïve mice resulted in a loss of CHS responsiveness. Transfer of both CD4+ and CD8+ cells was required for maximal loss of CHS responses, with CD8+ cells playing a major role. Significantly enhanced levels of IL-10 mRNA were detected in CD8+ T cells, but not in CD4+ T cells, following LF treatment of mice. LF also suppressed CHS responses in mice previously sensitized and challenged with hapten, when administered together with the hapten. Our data suggest that LF induces a long-lived tolerance in mice by inducing CD8+ and CD4+ regulatory T cells.

Lactoferrin is synthesized by activated microglia in the human substantia nigra and its synthesis by the human microglial CHME cell line is upregulated by tumor necrosis factor α or 1-methyl-4-phenylpyridinium treatment

The presence of the iron-binding protein lactoferrin (Lf) in some specific areas of the central nervous system and particularly in the normal human substantia nigra, where it is found in dopaminergic (DA) neurons and some glial cells, led us to investigate Lf synthesis in this area. Lf mRNA were identified using in situ hybridization and found in small ameboid cells. These cells were identified using immunocytochemistry as activated microglia since they exhibited macrophage markers such as the CD68 and the CR1 antigens. Double immunofluorescent labeling confirmed that the two Lf immunostained cell populations were activated microglia and DA neurons. Since activated microglia contained both Lf and its messenger, these cells are the Lf producing cells. The presence of Lf in DA neurons in which no Lf messengers were visible, might be due to an endocytosis mechanism, DA neurons probably internalizing Lf produced in microglial cells located in their neighborhood. In neuropathological disorders, such as Alzheimer’s and Parkinson’s diseases, inflammatory process and oxidative stress are events that contribute to neuronal death. Since Lf concentration increases during these pathologies, we studied the level of Lf expression under these different stresses and showed, using RT-PCR, that the immortalized human embryonic microglial CHME cell line produced Lf transcripts under tumor necrosis factor α or 1-methyl-4-phenylpyridinium treatment whereas untreated cells did not. These data confirm that Lf is produced only when microglia are activated.

LF 16.0335, a novel potent and selective nonpeptide antagonist of the human bradykinin B2 receptor.

1. In the present paper, we describe the in vitro pharmacological properties of LF 16.0335 (1-[[3-[(2,4-dimethylquinolin-8-yl)oxymethyl]-2,4-dichloro-p henyl]sulphonyl] -2(S) - [[4 -[4-(aminoiminomethyl)phenylcarbonyl]piperazin-1-yl]ca rbonyl]pyrrolidine), a novel and potent nonpeptide antagonist of the human bradykinin (BK) B2 receptor. 2. LF 16.0335 displaced [3H]-BK binding to membrane preparations from CHO cells expressing the cloned human B2 receptor, INT 407 cells and human umbilical vein with Ki values of 0.84+/-0.39 nM, 1.26+/-0.68 nM and 2.34+/-0.36 nM, respectively. 3. In saturation binding studies performed in INT 407 cell membranes in the presence or absence of LF 16.0335, max values of [3H]-BK were not significantly changed suggesting that LF 16.0335 behaves as a competitive antagonist. 4. LF 16.0335 had no affinity for the cloned human kinin B1 receptor stably expressed in 293 cells. In addition, this compound at 1 microM did not significantly bind to a range of 40 different membrane receptors and eight ion channels except muscarinic M2 and M1 receptors for which an IC50 value of 0.9 and 1 microM was obtained. 5. BK stimulates in a concentration-dependent manner phosphoinositosides (IPs) production in cultured INT 407 cells. Concentration-response-curves to BK were shifted to the right in the presence of LF 16.0335 (0.1 microM) without reduction of the maximum. LF 16.0335 inhibited the concentration-contraction curve to BK in the human umbilical vein giving a pA2 value of 8.30+/-0.30 with a Schild plot slope that was not different from unity. 6. These results demonstrate that LF 16.0335 is a potent, selective and competitive antagonist of the human bradykinin B2 receptor.

Effect of lactoferrin on the phagocytic activity of polymorphonuclear leucocytes isolated from blood of patients with autoimmune diseases and Staphylococcus aureus allergy.

Phagocytic number (PN) and phagocytic index (PI) of neutrophils isolated from blood of patients with autoimmune diseases, allergy to Staphylococcus aureus and from blood of healthy individuals were examined. Our results concerning the influence of lactoferrin (Lf); (6.7 mg/l) on the PI of PMN showed that: 1) Lf enhances reliable PI of PMN at the 30-th minute starting the phagocytic reaction in patients with autoimmune disease in an active stage, in blood donors treated as healthy with the presence of autoantibodies, in patients with autoimmune diseases and proved autoantibodies against tissue, cell antigens and collagen, 2) Lf influences non-significantly PI of PMN in patients with autoimmune collagen diseases in remission, 3) Lf increases PI of PMN with 19% only in 58% from the assessed patients with Staphylococcus aureus, and 4) Lf decreases non-significantly PI of PMN in the healthy controls. Our studies on the effect of Lf on the phagocytic activity of PMN suggest that Lf has stronger effect on the PN compared to the PI: 1) Lf enhances with 86% the PN in patients with Staphylococcus aureus, 2) Lf increases PN of PMN in all of the assessed patients with autoimmune collagen diseases in active stage (mean with 72%), and 3) Lf increases PN of PMN in 4 from the 5 investigated healthy controls (mean with 22%). Our results show a "corrective" effect of Lf on the phagocytic functions in the investigated groups of patients. The possible mechanisms, by which Lf increases PN and PI of neutrophils, is discussed: 1) they may concern the antioxidative properties of Lf to block the iron ions in their catalytic inactive form or to take part as ferric-Lf in an oxidative-reduction processes on the plasma membrane and controlling transmembrane transport systems, 2) Lf decreases the negative surface charge and thus enhances the adherent ability of the PMN. Probably to this stimulated adherent ability dues the increased ingestion of bacteria in the presence of Lf, and 3) The "changed" membrane of PMN may have higher number receptors for Lf to bind more molecules of exogenous Lf. The increase of Lf binding which enhances the adherence and aggregation of neutrophils, facilitates the phagocytosis.

Gastric Juice Levels of Lactoferrin and Helicobacter pylori Infection

Background: Recently, in vitro studies suggested that lactoferrin (Lf) might play an important role in the physiopathology of Helicobacter pylori-associated gastritis. However, whether Lf is present in the gastric juice and its relationship with H. pylori infection have not as yet been reported. In the present investigation the presence of Lf in gastric juice and its correlation with H. pylori infection were assessed. Methods: This study comprised 30 H. pylori-positive and 14 -negative patients with chronic gastritis. Gastric juice levels of Lf were measured with enzyme-linked immunoassays. Gastric juice concentration of Lf was also investigated in accordance with the histologic findings of biopsy specimens in the gastric body and antrum. Results: Lf concentration in gastric juice was significantly higher in H. pylori-positive than in -negative patients (P=0.033). The pH values are known to influence the levels of Lf. However, intragastric Lf levels were also significantly increased in H. pylori-positive patients as compared with H. pylori-negative patients after correcting the Lf levels for pH values (P = 0.029) or after adjusting the pH values of the gastric juice with NaHCO3 solution in both groups of patients (P = 0.0007). in addition, the gastric juice levels of Lf correlated significantly with the gastric mucosal concentrations of Lf in the gastric body (P < 0.005, r=0.568) and the antrum (P < 0.05, r=0.401). Conclusions: This study showed for the first time that Lf is present in gastric juice and that it correlates with H. pylori infection. Lf may constitute a good marker for H. pylori-associated gastritis. Although correlation does not prove causation, this study suggests that Lf might play an important role in the physiopathology of H. pylori-associated gastritis.

Lactoferrin interaction with salmonellae potentiates antibiotic susceptibility in vitro

Interaction of lactoferrin (Lf) with the cell envelope (CE) and outer membrane (OM) of Salmonella typhimurium- type strain ATCC13311 was tested by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western-blot analyses. The peroxidase-labeled bovine Lf (BLf) and human Lf both recognized a heat-modifiable protein with an estimated molecular mass of 38 kD in the OM. Simultaneous immunoblotting with an antiporin monoclonal antibody specific for a conserved porin domain in members of enterobacteriaceae confirmed that the Lf-binding protein is a porin. Such Lf-binding porin proteins (37–39 kD range) were readily detected in nine other common Salmonella species: S. dublin, S. panama, S. rostock, S. abony, S. hartford, S, kentucky, S. pullorum, S. thompson , and S. virchow . The latter six species also demonstrated one to three weak Lf-reactive bands of low molecular weight in their CE. The antibiotic susceptibility of Salmonella in the presence of Lf was examined. A mixture containing sub-minimum inhibitory concentration (MIC) levels of Lf (MIC/4) and cefuroxime (MIC/2) inhibited the bacterial growth. Lf strongly potentiated the action of erythromycin (eightfold), whereas it increased the activity only by two-fold for ampicillin, ciprofloxacin, chloramphenicol, and rifampicin; similarly, these antibiotics also reduced the MIC of BLf by twofold in S. typhimurium . Such antimicrobial potentiation was not observed with BLf mixtures containing cefalexin, gentamycin, or polymyxin B against strain ATCC13311. BLf and cefuroxime also demonstrated potentiation of varying degrees (two to 16-fold) with nine other Salmonella species. These data established the binding of Lf to porins in salmonellae and a potentiation effect of Lf with certain antibiotics.

Role of quantum effects in the breakdown of gases by laser radiation

A theoretical investigation is made of the development of avalanche ionization of a gas by an optical pulse. The nonmonotonic dependence of the optical breakdown threshold on the radiation frequency is shown to be related to the quantum nature of changes in the electron energy in the field of an optical wave. A steep fall of the threshold in the ultraviolet range is due to a high probability of penetration of an electron to an ionization region as a result of a quantum jump across the zone representing losses due to excitation of the atomic levels. This theory is compared with experimental results on the breakdown of rare gases. An investigation is reported of the optical breakdown in the presence of lf, microwave, or static fields. It is shown that the reduction in the optical breakdown threshold under these conditions is due to quantum effects.

Lactoferrin decreases monocyte-induced fibroblast production of myeloid colony-stimulating activity by suppressing monocyte release of interleukin-1

Lactoferrin (Lf) is a negative regulator of myelopoiesis which operates by suppressing the release from mononuclear phagocytes of GM colony- stimulating factor (GM-CSF) or monokines which can then induce the release of GM-CSA from accessory cells. In this study, endotoxin- depleted, purified iron-saturated human Lf was assessed for its effect on the production of interleukin-1 by cultured monocytes and their subsequent effect on colony-stimulating factor release from cultured fibroblasts. Monocytes were grown with or without Lf and Lf that had previously been incubated with monoclonal anti-Lf. The monocyte- conditioned medium was then either assayed for the presence of interleukin-1 (IL-1) with an enzyme-linked immunosorbent assay or for its ability to stimulate fibroblasts to release growth factors for CFU- GM, BFU-E, or CFU-Mix colonies. In the presence of Lf (10(-7) or 10(-8) mol/L), GM colony-stimulating activity (GM-CSA) was suppressed by 31% to 73%, whereas stimulating activities for BFU-E and CFU-mix colony formation were suppressed by 93% to 100%. Antibody to Lf completely abrogated the suppressive effects observed with Lf, whereas antibody to IL-1 ablated the induction by monocyte-conditioned medium of CSA release by fibroblasts. Lf at 10(-7) and 10(-8) mol/L also reduced IL-1 synthesis by cultured monocytes from 60% to 77%. The inhibitory effects of Lf were only observed when Lf was added before adherence of the monocytes for culture. If Lf was added at the time of adherence or after adherence, no suppression was observed. We conclude that the inhibition of GM-CSA production/release by Lf is mediated through inhibition of the synthesis/release of IL-1 by mononuclear phagocytes. This inhibition of IL-1 prevents accessory cells from producing and/or releasing GM-CSA.

Lactoferrin Decreases Monocyte-Induced Fibroblast Production of Myeloid Colony-Stimulating Activity by Suppressing Monocyte Release of Interleukin-l

Lactoferrin (Lf) is a negative regulator of myelopoiesis which operates by suppressing the release from mononuclear phagocytes of GM colony-stimulating factor (GM-CSF) or monokines which can then induce the release of GM-CSA from accessory cells. In this study, endotoxin-depleted, purified iron-saturated human Lf was assessed for its effect on the production of interleukin-1 by cultured monocytes and their subsequent effect on colony-stimulating factor release from cultured fibroblasts. Monocytes were grown with or without Lf and Lf that had previously been incubated with monoclonal anti-Lf. The monocyte-conditioned medium was then either assayed for the presence of interleukin-1 (IL-1) with an enzyme-linked immunosorbent assay or for its ability to stimulate fibroblasts to release growth factors for CFU-GM, BFU-E, or CFU-Mix colonies. In the presence of Lf (10(-7) or 10(-8) mol/L), GM colony-stimulating activity (GM-CSA) was suppressed by 31% to 73%, whereas stimulating activities for BFU-E and CFU-mix colony formation were suppressed by 93% to 100%. Antibody to Lf completely abrogated the suppressive effects observed with Lf, whereas antibody to IL-1 ablated the induction by monocyte-conditioned medium of CSA release by fibroblasts. Lf at 10(-7) and 10(-8) mol/L also reduced IL-1 synthesis by cultured monocytes from 60% to 77%. The inhibitory effects of Lf were only observed when Lf was added before adherence of the monocytes for culture. If Lf was added at the time of adherence or after adherence, no suppression was observed. We conclude that the inhibition of GM-CSA production/release by Lf is mediated through inhibition of the synthesis/release of IL-1 by mononuclear phagocytes. This inhibition of IL-1 prevents accessory cells from producing and/or releasing GM-CSA.