Dynamic interactions of neutrophils and biofilms

BACKGROUND

The majority of microbial infections in humans are biofilm-associated and difficult to treat, as biofilms are highly resistant to antimicrobial agents and protect themselves from external threats in various ways. Biofilms are tenaciously attached to surfaces and impede the ability of host defense molecules and cells to penetrate them. On the other hand, some biofilms are beneficial for the host and contain protective microorganisms. Microbes in biofilms express pathogen-associated molecular patterns and epitopes that can be recognized by innate immune cells and opsonins, leading to activation of neutrophils and other leukocytes. Neutrophils are part of the first line of defense and have multiple antimicrobial strategies allowing them to attack pathogenic biofilms.

OBJECTIVE/DESIGN

In this paper, interaction modes of neutrophils with biofilms are reviewed. Antimicrobial strategies of neutrophils and the counteractions of the biofilm communities, with special attention to oral biofilms, are presented. Moreover, possible adverse effects of neutrophil activity and their biofilm-promoting side effects are discussed.

RESULTS/CONCLUSION

Biofilms are partially, but not entirely, protected against neutrophil assault, which include the processes of phagocytosis, degranulation, and formation of neutrophil extracellular traps. However, virulence factors of microorganisms, microbial composition, and properties of the extracellular matrix determine whether a biofilm and subsequent microbial spread can be controlled by neutrophils and other host defense factors. Besides, neutrophils may inadvertently contribute to the physical and ecological stability of biofilms by promoting selection of more resistant strains. Moreover, neutrophil enzymes can degrade collagen and other proteins and, as a result, cause harm to the host tissues. These parameters could be crucial factors in the onset of periodontal inflammation and the subsequent tissue breakdown.

[Patient education for self-management of oral anticoagulation - situation in Hesse]

AIM

Oral anticoagulation (OAC) has been shown to be highly effective in preventing thromboembolic complications. Self-management can enable patients with a long-term indication for OAC to be actively involved in the therapy, but in Germany the implementation of self-management is linked to mandatory training. To illustrate significant structural disparities between education centres in Hesse, all such centres were identified and a list generated, specifying the differences.

METHOD

Using our own questionnaire, we interviewed all known patient education centres in Hesse between January and July 2012, and conducted a descriptive analysis of their structural features.

RESULTS

There were 44 datasets for statistical interpretation. We distinguished between centres with ASA certification (n=19) and centres without (n=25). On average, certified centres provide 6 h of training (range 2-9) compared to 5.5 h (range 1-12) in uncertified centers. Certified centres hold more group sessions per year (on average 17 vs. 8) and more individual training sessions (on average 10 vs. 5). Certified centres train 10-365 patients per year and uncertified centers between 5 and 77. Certified centres offer retraining more frequently (84% vs. 40%) and more often conclude the training with a written test (74% vs. 44%). Only 9 centres provide materials for patients with a migration background.

CONCLUSION

The results show that in Hesse, severe structural discrepancies exist in training programmes for self-management of OAC, and it can be assumed that patients participating in trainings in different Hessian education centres face very differing conditions. To improve the quality of the trainings and to ensure patients have similar levels of knowledge, it is imperative that centres be regularly inspected with the help of proven quality indicators.

[Measurement of tissue-shift for head neck rotation]

BACKGROUND

During neck surgery the head of the patient is located in such a position that the neck-tissue is deformed compared to the normal head-position. The consideration of this tissue deformation of the neck during head rotation is the first step to using preoperative image data for medical navigation.

MATERIAL AND METHODS

The tissue shift was measured and analyzed based on MRT-image data of a subject group of 5 patients.

RESULTS

The big vessels, lying contralateral to the rotation, demonstrated a larger shift than those vessels, lying ipsilateral. The shift was nonlinear to the head rotation and the shift of the V. jugularis interna was less pronounced than the shift of the A. carotis communis even though they both run in the same adventitia. In the cranial neck section, the movement of the tissue was larger than in the caudal neck section.

CONCLUSION

The knowledge about tissue shifts in different head positions should promote intraoperative, minimally invasive procedures. The expectation is that such examinations facilitate the navigation in neck surgery with online calculation of tissue shifts.

The antimicrobial activity of the appetite peptide hormone ghrelin

The present study examined the antimicrobial activity of the peptide ghrelin. Both major forms of ghrelin, acylated ghrelin (AG) and desacylated ghrelin (DAG), demonstrated the same degree of bactericidal activity against Gram-negative Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa), while bactericidal effects against Gram-positive Staphylococcus aureus (S. aureus) and Enterococcus faecalis (E. faecalis) were minimal or absent, respectively. To elucidate the bactericidal mechanism of AG and DAG against bacteria, we monitored the effect of the cationic peptides on the zeta potential of E. coli. Our results show that AG and DAG similarly quenched the negative surface charge of E. coli, suggesting that ghrelin-mediated bactericidal effects are influenced by charge-dependent binding and not by acyl modification. Like most cationic antimicrobial peptides (CAMPs), we also found that the antibacterial activity of AG was attenuated in physiological NaCl concentration (150mM). Nonetheless, these findings indicate that both AG and DAG can act as CAMPs against Gram-negative bacteria.

Aspirin reduces the incidence of second eye NAION: a retrospective study

The objective of this study was to determine if aspirin reduces the incidence of second eye involvement after nonarteritic anterior ischemic optic neuropathy (NAION) in one eye. Records were reviewed of 131 patients who sustained unilateral NAION. Of these, the 33 patients who sustained second eye NAION were compared to those followed for a minimum of 2 years without sustaining a second eye NAION (67). Thirty-one of the 131 patients were excluded because of inadequate follow-up. Except for diabetes (relative risk [RR] 1.43, p = 0.05), the incidence of second eye NAION was independent of gender, age, cup/disk, hypertension, anemia, and migraine. The degree of visual acuity or field dysfunction in the first eye correlated poorly with the acuity (r = 0.28) and field (r = 0.33) loss in the second eye. Aspirin (65-1,300 mg) taken two or more times per week decreased the incidence (17.5% vs. 53.5%) and relative risk (RR = 0.44, p = 0.0002) of second eye AION regardless of the usual risk factors. Even after eliminating those patients who had bilateral disease when first referred, ASA still reduced the incidence of second eye involvement (35% vs. 13%, RR = 0.74, p = 0.01). Aspirin may be an effective means of reducing second eye NAION.

Iodoaminopotentidine and related compounds: a new class of ligands with high affinity and selectivity for the histamine H2 receptor

The synthesis and biological evaluation of a new class of histamine H2 antagonists with N-cyano-N'-[omega-[3-(1-piperidinylmethyl)phenoxy] alkyl]guanidine partial structure are described as part of an extensive research program to find model compounds for the development of new radioligands with high H2 affinity and specific activity. High receptor affinity is achieved by an additional (substituted) aromatic ring, which is connected with the third guanidine N by a carbon chain spacer and an amine, carboxamide, ester, or sulfonamide link ("polar group"). In functional studies for H2 antagonistic activity and other pharmacological actions [e.g. H1 antihistaminic, antimuscarinic, antiadrenergic (alpha 1, beta 1), 5-HT2 blocking activity] in the isolated guinea pig atrium and ileum and rat aorta and tail artery, the compounds proved to be highly potent and selective histamine H2 receptor antagonists. The H2 antagonistic activity is mainly depending on the length of both the N'-alkyl chain (chain A) and the N"-spacer (chain B). Compounds with a C3 chain A and a C2 chain B are most potent in the preferred group of substances, i.e., the carboxamide series. A wide variety of substituents at the aromatic ring is tolerated, among them iodine, amino, and azido groups. These compounds are up to 32 times more potent than cimetidine in the isolated guinea pig right atrium. The replacement of the carboxamide by an ester group (44c) is well tolerated, while replacement of the cyanoguanidine by an urea group results in nearly 100-fold decrease in activity (46c,e). The iodinated benzamides are among the most potent H2 antagonists known so far. The [125I]-labeled form of 31f ([125I]iodoaminopotentidine, [125I]-N-[2-(4-amino-3-iodobenzamido) ethyl]-N'-cyano-N"-[3-[3-(1-piperidinylmethyl) phenoxy]propyl]guanidine) and its photolabile analogue 31h ([125I]iodoazidopotentidine, [125I]-N-[2-(4-azido-3- iodobenzamido)ethyl]-N'-cyano-N"-[3-[3-(1-piperidinyl-methyl)pheno xy] propyl]guanidine) proved to be useful probes for reversible and irreversible labeling of the histamine H2 receptor. Radioligand binding studies in guinea pig cerebral membranes revealed considerably higher H2 receptor affinity for 31f (pKi = 9.15), 31h (pKi = 8.58), and some analogues than functional experiments (guinea pig atrium), presumably reflecting an easier access to the H2 receptors in membranes.

Reversible and irreversible labelling of H1- and H2 -receptors using novel [125I] probes

We have recently designed the first 125I-labelled probes specific for the histamine H1 and H2 receptors. These reversible and irreversible antagonists are among the most potent H1 and H2 ligands and have enabled investigations into the biochemical and pharmacological properties of these two receptors. In various brain animal species, the ligand binding peptide of the H1 and H2 receptors, as determined by photoaffinity labeling, resides within 56-59 kDa peptides. In contrast, in guinea pig heart, the ligand binding domain of the H1 receptor is characterized by a higher molecular weight (68 kDa), suggesting the presence of an isoform of this protein, clearly differentiable by this biochemical property but not by its pharmacology. The reversible 125I-probes allowed us to extend the pharmacology of these receptors in several biological preparations and in human brain, and to establish their interaction with G-proteins. A detailed mapping of H1 and, for the first time, of H2 receptors, has been achieved in guinea pig brain, establishing their presence in almost all brain areas. These experiments show that there is no correlation between the density of H2 receptor and the activity of adenylate cyclase sensitive to histamine suggesting a molecular heterogeneity of this receptor.

Reversible and irreversible labeling and autoradiographic localization of the cerebral histamine H2 receptor using [125I]iodinated probes

Iodoaminopotentidine (I-APT)--i.e., N-[2-(4-amino-3-iodobenzamido)ethyl]-N'-cyano-N''-(3-[3- (1-piperidinylmethyl)phenoxy]propyl)guanidine--represents one of the most potent H2-receptor antagonists known so far. In membranes of guinea pig brain 125I-APT bound reversibly, selectively, and with high affinity (Kd = 0.3 nM) to a homogeneous population of sites unambiguously identified as H2 receptors by inhibition studies conducted with a large panel of antagonists. 125I-APT binding was also inhibited by histamine, and the effect was modulated by a guanyl nucleotide, which is consistent with the association of the H2 receptor with a guanine nucleotide binding regulatory protein. The low nonspecific binding of 125I-APT generated high contrast autoradiographic pictures in brain sections and established the precise distribution of H2 receptors. Their highly heterogeneous distribution and laminated pattern in some areas--e.g., cerebral and hippocampal cortices--suggest their major association with neuronal elements. These localizations were more consistent than those of H1 receptors with the distribution of histaminergic projections, indicating that H2 receptors mediate a larger number of postsynaptic actions of histamine--e.g., in striatum. Colocalizations of H1 and H2 receptors in some areas account for their known synergistic interactions in cAMP formation induced by histamine. The distribution of 125I-APT binding sites did not strictly parallel that of the H2-receptor-linked adenylate cyclase activity, which may reflect heterogeneity among H2 receptors. After UV irradiation and SDS/PAGE analysis, [125I]iodoazidopotentidine (125I-AZPT), a photoaffinity probe derived from 125I-APT, was covalently incorporated in several peptides, among which the labeling of two peptides of 59 and 32 kDa was prevented by H2 antagonists, suggesting that they correspond to H2-receptor binding peptides or proteolysis products of the latter. These probes should be useful for sensitive radioassays, localization, purification, and molecular studies of the H2 receptor, which were previously impracticable.

Conceptual framework shifts in immunogenetics. II. Some notes on the Ag system

Two Caucasian population materials totalling 530 individuals and 3,180 typing results are analyzed with regard to various combinations of the Ag(x, y, a1, d, c, g) factors. Superficially, both materials appear well aligned to each other and the contemporary (simple-complex) framework. However, when the same set of data are structuralized within a new (complex-simple) framework, the typing results for 12 of 362 or 3.3% of the Swiss and no less than 19 of 168 or 11.3% of the English samples are not compatible with the new framework specifying that the various anti-Ag reagents can be arranged in two 'inclusion groups'--the anti-Ag (y greater than d greater than c) and the anti-Ag (g greater than a1 greater than x) series.

Conceptual framework shifts in immunogenetics. I. A new look at cis AB antigens in the ABO system

The so-called 'cis AB' blood group is accounted for by proposing that 'normal' anti-A and anti-B reagents are cross-reacting with partially overlapping reaction ranges. Hence, they are labelled anti-AX and anti-BX, respectively. Some consequences of a complex-simple model where 'cis AB' is accordingly produced by a simple (mono-factorial) antigen X (produced a simple gene X at the ABO-locus) are briefly explored.

Towards a unified theory for immunogenetic systems. Some selected properties of ABC- and AB-D reaction patterns generated by S3 and T3 universes

The principles of a radically new unified theory and a unified but fundamentally theory-invariant classification system are described and exemplified for immunogenetic systems. The classification system permits a differentiation of immunogenetic systems into 15 qualitatively distinct classes with quantitative subsets when tested against two reagents. It can easily be expanded into a n-reagent taxonomy. The theory logically explains a set of selected and previously more or less "unexplainable" properties and their (even more unexplainable and probably previously unnoticed) associations in two main classes of immunogenetic systems, the ABC- and AB-D systems. The associated properties discussed are the presence (+) or absence (-) of: 1. antithetical alleles; 2. dosage effects; 3. inherited "strong" and "weak" antigens; 4. "silent" or "amorphous" genes. In ABC- systems, properties 1 and 2 are present while 3 and 4 are absent or extremely rare (i.e. 1+2+3-4-). In AB-D systems, properties 1 and 2 are absent while 3 and 4 are present (i.e. 1-2-3+4+). Through the design of hypothetical immunogenetic universes (HIU), these property associations are shown to be produced by the contemporary (simple-complex) framework-dependent transformations of experimental observables/matrix facts and not by any corresponding associated properties present in the input HIU in themselves.