Computational Fluid Dynamics of Fish Gill Rakers During Crossflow Filtration

We study crossflow filtration mechanisms in suspension-feeding fishes using computational fluid dynamics to model fluid flow and food particle movement in the vicinity of the gill rakers. During industrial and biological crossflow filtration, particles are retained when they remain suspended in the mainstream flow traveling across the filter surface rather than traveling perpendicularly to the filter. Here we identify physical parameters and hydrodynamic processes that determine food particle movement and retention inside the fish oral cavity. We demonstrate how five variables affect flow patterns and particle trajectories: (1) flow speed inside the fish oral cavity, (2) incident angle of the flow approaching the filter, (3) dimensions of filter structures, (4) particle size, and (5) particle density. Our study indicates that empirical experiments are needed to quantify flow parameters inside the oral cavity, and morphological research is needed to quantify dimensions of the filter apparatus such as gill rakers, the gaps between rakers, and downstream barriers. Ecological studies on suspension-feeding fishes are also needed to quantify food particle size and density, as these variables can affect particle retention due to hydrodynamic processes during crossflow filtration.     

Effect of probiotics on intestinal mucosal immunity and ultrastructure of cecal tonsils of chickens

Sixty chickens were randomly divided into two groups to determine the effect of oral administration of probiotics on the intestinal mucosal immune response and ultrastructure of cecal tonsils. The first group (control) was fed with a basic diet without antibiotic or probiotics. The second group was fed with the same diet as the control, except they received drinking water with probiotics (4 x 10(9) cfu per chicken and day) from posthatch to day 3 of age. The probiotic preparation was composed of Bacillus subtilis Bs964, Candida utilis BKM-Y74 and Lactobacillus acidophilus LH1F. Intestinal fluid, Peyer's Patch and cecal tonsils were taken at day 1, 4, 7, 10 and 18 after administration of probiotics. The results showed: (i) Compared to the control, probiotics enhanced the content of following items: immunglobulin (Ig)A in the intestinal fluid at day 7 (p < 0.01), the IgG-forming cells at day 10 (p < 0.05), IgM-forming cells in the Peyer's Patch at day 7 (p < 0.05), IgA-forming cells at day 7-10 (p < 0.05), IgG-forming cells at day 7 (p < 0.05) and IgM-forming cells in cecal tonsils diffuse area at day 4-7 (p < 0.05). (ii) T lymphocytes in cecal tonsils were enhanced at day 7 (p < 0.01) after orally fed with probiotics. (iii) The density of microvilli and length of cecal tonsils increased after probiotics were administrated at day 3. With chicken ageing, the efficiency of probiotics would decrease. These results suggested that probiotics enhance intestinal mucosal immunity of chicken at the early age.     

Oral Inoculation of Young Dairy Calves with Mycoplasma bovis Results in Colonization of Tonsils, Development of Otitis Media and Local Immunity

Because M. bovis otitis media is an economically important problem, there is a need to understand the pathogenesis of disease, not only to improve our understanding of the factors contributing to the development of this disease but also to inform the development of improved diagnostic tests and therapy. Oral ingestion of M. bovis-contaminated milk is linked, but not definitively proven, to development of otitis media. In the current study, we demonstrate that oral ingestion of M. bovis infected colostrum can result in an ascending infection and development of otitis media. Importantly, M. bovis was found to have a previously unrecognized tendency for colonization of the tonsils of calves, which most likely contributed to the subsequent development of otitis media. In contrast, transtracheal inoculation failed to produce clinically significant upper respiratory tract disease, although did induce lower respiratory tract disease. The upper respiratory tract was the major site of M. bovis-specific B cell and mucosal IgA responses in calves inoculated by the oral route. The oral inoculation route of infection presented here is particularly suited to the study of host-pathogen interactions during initial colonization of the tonsils, expansion of infection and dissemination to the lower respiratory tract and middle ear. In addition, it could be used to investigate potential new preventative or control strategies, especially those aimed at limiting colonization of the tonsils and/or spread to the middle ear.     

Effect of probiotics on intestinal mucosal immunity and ultrastructure of cecal tonsils of chickens

Abstract

Sixty chickens were randomly divided into two groups to determine the effect of oral administration of probiotics on the intestinal mucosal immune response and ultrastructure of cecal tonsils. The first group (control) was fed with a basic diet without antibiotic or probiotics. The second group was fed with the same diet as the control, except they received drinking water with probiotics (4×10⁹ cfu per chicken and day) from posthatch to day 3 of age. The probiotic preparation was composed of Bacillus subtilis Bs964, Candida utilis BKM-Y74 and Lactobacillus acidophilus LH1F. Intestinal fluid, Peyer's Patch and cecal tonsils were taken at day 1, 4, 7, 10 and 18 after administration of probiotics. The results showed: (i) Compared to the control, probiotics enhanced the content of following items: immunglobulin (Ig)A in the intestinal fluid at day 7 (p < 0.01), the IgG-forming cells at day 10 (p < 0.05), IgM-forming cells in the Peyer's Patch at day 7 (p < 0.05), IgA-forming cells at day 7–10 (p < 0.05), IgG-forming cells at day 7 (p < 0.05) and IgM-forming cells in cecal tonsils diffuse area at day 4–7 (p < 0.05). (ii) T lymphocytes in cecal tonsils were enhanced at day 7 (p < 0.01) after orally fed with probiotics. (iii) The density of microvilli and length of cecal tonsils increased after probiotics were administrated at day 3. With chicken ageing, the efficiency of probiotics would decrease. These results suggested that probiotcs enhance intestinal mucosal immunity of chicken at the early age.     

Fluorescence fingerprints of oral bacteria

The rapid detection and identification of microorganisms is one of the most important factors in many cases of ill health. The purpose of this study was to determine the fluorescence characteristics of seven oral bacteria using emission spectra with the aim of distinguishing between the bacteria, and to compare fluorescence imaging methods for the direct assessment of oral bacteria. Fluorescence images of each bacterium were obtained under a 405‐nm light source using a two‐filter system. The emissions of all samples were measured with a fluorescence spectrometer. The complete fluorescence data set collected for each sample employed a three‐dimensional data cube. The differences in the autofluorescence characteristics of the seven oral bacteria were determined by principal components analysis (PCA). The fluorescence images of the oral bacteria varied with the genus and the filter system. The three‐dimensional excitation‐emission matrix fluorescence spectra exhibited distinctive fluorescence features associated with intracellular fluorophores. The seven bacteria could be clearly differentiated on the PCA score plot. The findings of this study indicate that oral bacteria can be identified based on their autofluorescence characteristics. Fluorescence spectroscopy coupled with PCA can be used to detect and classify oral bacteria.      

Experimental infection of European wild swine (Sus scrofa L.) with pseudorabies virus

Experimental infection with pseudorabies virus was carried out by oral exposure of four young wild swine held in contact with two unexposed controls. No disease was observed but virological procedures indicated that the virus was shed in saliva and, in one case, in the nasal discharge, with subsequent infection of the control animals. After slaughter the virus was reisolated from the tonsils but not from lungs and brain. Virus reisolation from the tonsils was obtained in two animals after the throat swabs became negative. Virus neutralizing antibodies were detected.     

Induction of salivary antibodies to inhibit Candida albicans adherence to human epithelial cells by tonsillar immunization in rabbits

To examine the possibility of a vaccine for Candida albicans infection in the oral cavity, we induced salivary antibodies by immunization of killed-C. albicans ATCC 18804 on the palatine tonsils of rabbits. The enzyme-linked immunosorbent assay reaction of salivary antibodies was high against C. albicans serotype A. The saliva antibodies greatly inhibited C. albicans adherence to cloned epithelial cells from human gingiva. Tonsillar immunizations of C. albicans ATCC 18804 induce salivary antibodies that prevent C. albicans adherence to epithelial cells, and thus should prove useful in the prevention of oral candidiasis caused by C. albicans serotype A.     

Differentiated S100A7 expression in infected tonsils and tonsils from allergic individuals

Palatine tonsils are continuously exposed to microorganisms and antigens and secrete antimicrobial peptides as a first line of defense. S100A7 is a protein with antimicrobial and chemotactic properties. Our aim was to investigate how the expression of S100A7 in human palatine tonsils is affected by inflammatory processes. Tonsils obtained from 109 patients undergoing tonsillectomy were divided into groups of infected and noninfected as well as allergic and nonallergic, based on the results from tonsillar core culture tests and Phadiatop analysis, respectively. Western blot and immunohistochemistry were used to assess protein expression and real-time PCR was used to quantify mRNA levels. To explore the induction of S100A7, tonsils were stimulated with lipopolysaccharide in vitro. The immunohistochemical staining for S100A7 was most intense in the tonsillar epithelium, but the protein was also detected in B- and T-cell regions, which was confirmed with Western blot on isolated B and T cells. The S100A7 expression appeared to be the highest in CD8+ T cells. Reduced mRNA levels of S100A7 were detected in infected tonsils as well as in tonsils from allergic individuals. In vitro stimulation of tonsils with lipopolysaccharide did not have any effect on the expression. The results suggest a role for S100A7 in recurrent tonsillitis and allergic disease.     

Biochemical features,molecular biology and clinical relevance of the human 15-domain serine proteinase inhibitor LEKTI

Based on the isolation of a 55 amino acid peptide from human hemofiltrate, we cloned the cDNA for a novel human 15-domain serine proteinase inhibitor termed LEKTI. A trypsin-inhibiting activity was demonstrated for three different domains. High levels of expression of the corresponding gene were detected in oral mucosa, followed by the tonsils, parathyroid glands, thymus, and trachea. Hovnanian and coworkers recently found that certain mutations within the LEKTI gene are linked to the severe congenital disease Netherton syndrome and atopic manifestations (including asthma). Thus, a future therapeutic use of LEKTI is conceivable.     

High prevalence of Yersinia enterocolitica 4:O3 on pig offal in southern Germany: a slaughtering technique problem

Prevalence and contamination routes of pathogenic Yersinia enterocolitica were studied in Southern Germany. Tonsil and faeces samples of 50 fattening pigs, 140 offal samples and 120 minced meat samples were examined. Pig and offal samples were collected from a slaughterhouse approved by the European Union, and minced meat samples from two large meat factories. Yersinia enterocolitica was isolated using direct plating, overnight enrichment and selective enrichment in MRB and ITC broth. The isolates were bio- and serotyped, and pathogenicity was studied using two plasmid-encoded virulence markers: calcium dependence and Congo red absorption. The genotypes were studied with pulsed-field gel electrophoresis using NotI enzyme. Prevalence of pathogenic Y. enterocolitica 4:O3 was 60% and 10% in tonsils and faeces of fattening pigs, respectively. Besides tonsils, prevalence of pathogenic Y. enterocolitica 4:O3 was also high in other pluck set samples, including tongues, lungs, hearts, diaphragms and livers. However, the highest isolation rate was obtained from the tonsils. Kidneys, which were not attached to the pluck set and did not hang together with tonsils on the rack, had the lowest isolation rate. Yersinia enterocolitica 4:O3 was isolated from 12% of minced meat samples. A total of 25 NotI profiles were obtained from porcine samples. The most common genotype, NBI, found in tonsils was also the most common type recovered from offal and minced meat samples. The high contamination rate of tonsils, and the indistinguishable NotI profiles obtained from tonsils and offal indicate that the tonsils contaminate offal when they are removed and hung on the rack together. When the head, with the tonsils and tongue, is not removed prior to evisceration and is not handled and inspected separately, it is difficult to control the spread of Y. enterocolitica 4:O3 from tonsils to the carcass, and subsequently, to meat.     

Levels of immunoglobulins and lysozyme in 10-year-old children from different regions and the condition of the lymphatic apparatus. I. Condition of tonsils in connection with some immunological parameters and different environment

The condition of tonsils was investigated and the levels of serum IgG, IgA, IgM and lysozyme were measured in 305 ten-year-old children from three localities of the Central-Bohemian Region. The tonsils were not enlarged in 30.8% of children, in 26.2% they were enlarged, in 35.5% furrowed and in 7.5% of children tonsillectomy had been carried out. Mean levels of IgA were significantly higher in two localities in children with enlarged tonsils, insignificantly lower in children with furrowed tonsils and lowest in tonsilectomized children. The difference in the distribution of IgM levels were significant between girls with enlarged furrowed tonsils. The levels of lysozyme were not correlated with the finding in the tonsils, but a significant difference was found in the groups with enlarged tonsils between the three locailties under observation and in the groups with furrowed tonsils between two localities. The importance of the findings observed is discussed from the point of view of a possible influence of air pollution in two of the three localities under study.     

Evidence of a true pharyngeal tonsil in birds: a novel lymphoid organ in Dromaius novaehollandiae and Struthio camelus (Palaeognathae)

ABSTRACT: BACKGROUND: Tonsils are secondary lymphoid organs located in the naso- and oropharynx of most mammalian species. Most tonsils are characterised by crypts surrounded by dense lymphoid tissue. However, tonsils without crypts have also been recognised. Gut-associated lymphoid tissue (GALT), although not well-organised and lacking tonsillar crypts, is abundant in the avian oropharynx and has been referred to as the "pharyngeal tonsil". In this context the pharyngeal folds present in the oropharynx of ratites have erroneously been named the pharyngeal tonsils. This study distinguishes between the different types and arrangements of lymphoid tissue in the pharyngeal region of D. novaehollandiae and S. camelus and demonstrates that both species possess a true pharyngeal tonsil which fits the classical definition of tonsils in mammals. RESULTS: The pharyngeal tonsil (Tonsilla pharyngea) of D. novaehollandiae was located on the dorsal free surface of the pharyngeal folds and covered by a small caudo-lateral extension of the folds whereas in S. camelus the tonsil was similarly located on the dorsal surface of the pharyngeal folds but was positioned retropharyngeally and encapsulated by loose connective tissue. The pharyngeal tonsil in both species was composed of lymph nodules, inter-nodular lymphoid tissue, mucus glands, crypts and intervening connective tissue septa. In S. camelus a shallow tonsillar sinus was present. Aggregated lymph nodules and inter-nodular lymphoid tissue was associated with the mucus glands on the ventral surface of the pharyngeal folds in both species and represented the Lymphonoduli pharyngeales. Similar lymphoid tissue, but more densely packed and situated directly below the epithelium, was present on the dorsal, free surface of the pharyngeal folds and represented a small, non-follicular tonsil. CONCLUSIONS: The follicular pharyngeal tonsils in D. novaehollandiae and S. camelus are distinct from the pharyngeal folds in these species and perfectly fit the classical mammalian definition of pharyngeal tonsils. The presence of a true pharyngeal tonsil differentiates these two ratite species from other known avian species where similar structures have not been described. The pharyngeal tonsils in these ratites may pose a suitable and easily accessible site for immune response surveillance as indicated by swelling and inflammation of the tonsillar tissue and pharyngeal folds. This would be facilitated by the fact that the heads of these commercially slaughtered ratites are discarded, thus sampling at these sites would not result in financial losses.     

Histological studies on the development of porcine tonsils after birth

Tonsils form the topographically first immune barrier of an organism against the invasion of pathogens. We used histology to study the development of tonsils of pigs after birth. At birth, the tonsils consist of diffuse lymphoid tissue without any lymphoid follicle aggregations. At the age of 7 days, lymphoid follicles appeared in the soft palate tonsil. The lymphoid layer of the nasopharyngeal tonsil, soft palate tonsil, and lingual tonsil became thicker, and lymphoid follicles in the lamina propria were clearly visible at the age of 21 days. Secondary lymphoid follicles were present in the nasopharyngeal tonsil at the age of 50 days, and in the soft palate tonsil at the age of 120 days. Dendritic cells (DCs), CD3⁺ T cells and IgA⁺ B cells in the soft palate tonsil, nasopharyngeal tonsil and lingual tonsil increased continuously, especially during the first 21 days. The results suggested that tonsils have an important role in local immune defense against invading antigens after birth and will be beneficial for understanding the mechanisms of immunity in these animals after nasal and oral vaccination.     

One-stage full-mouth disinfection to overcome intra-oral transmission of periodontopathogens

The oral cavity offers a range of different niches where periodontopathogens can adhere and survive (e.g. the mucosa, the tongue, the tonsils, the saliva and all intra-oral hard surfaces such as teeth, dentures, oral implants). Transmission of bacteria from one niche to another is likely to occur. Recent studies, for example, illustrated that initially sterile abutments of oral implants were rapidly colonized by bacteria from the subgingival environment around teeth. This transmission of bacteria can occur spontaneously via the saliva, or by means of oral hygiene aids and/or dental instruments. Such an intra-oral transmission, if it occurs at a high speed, could jeopardize the outcome of periodontal therapy. To overcome a bacterial transmission, a 'one-stage full-mouth disinfection' was recently introduced for the treatment of periodontal infections. This new treatment strategy resulted in significant clinical and microbiological improvements when compared with the standard sequential treatment.     

The fluid mechanics of bolus ejection from the oral cavity

The squeezing action of the tongue against the palate provides driving forces to propel swallowed material out of the mouth and through the pharynx. Transport in respose to these driving forces, however, is dependent on the material properties of the swallowed bolus. Given the complex geometry of the oral cavity and the unsteady nature of this process, the mechanics governing the oral phase of swallowing are not well understood. In the current work, the squeezing flow between two approaching parallel plates is used as a simplified mathematical model to study the fluid mechanics of bolus ejection from the oral cavity. Driving forces generated by the contraction of intrinsic and extrinsic lingual muscles are modeled as a spatially uniform pressure applied to the tongue. Approximating the tongue as a rigid body, the motion of tongue and fluid are then computed simultaneously as a function of time. Bolus ejection is parameterized by the time taken to clear half the bolus from the oral cavity, t_1/2. We find that t_1/2 increases with increased viscosity and density and decreases with increased applied pressure. In addition, for low viscosity boluses (μapproximately 1000 cP), viscosity dominates. A transition region between these two regimes is found in which both properties affect the solution characteristics. The relationship of these results to the assessment and treatment of swallowing disorders is discussed.     

The microenvironment of human Peyer's patches inhibits the increase in CD38 expression associated with the germinal center reaction

Analysis of B cells in the human tonsils identified CD38 expression as a hallmark of germinal center (GC) B cells. However, the signals responsible for the in vivo induction of CD38 have not been determined. The primary site for generation of memory and plasma cells in the gastrointestinal tract is the GCs of Peyer's patches (PP). PP and intestinal mucosa, but not tonsils or oral mucosa, express mucosal addressin cell adhesion molecule-1 (MAdCAM-1). The ligand for MAdCAM-1, integrin alpha(4)beta(7), is expressed on naive B cells and memory B cells that traffic to the gastrointestinal tract. In this study we determine that, unlike tonsil, human PP GC B cells do not express significant levels of CD38. PP B cells can be induced to express CD38 upon culture with CD40 ligand, anti-B cell receptor, and IFN-gamma. However, coculture of tonsil naive B cells with an Ab directed against integrin beta(7) inhibits IFN-gamma-induced CD38 hyperexpression. The absence of CD38 on PP GCs suggests that there are tissue-specific pathways of B cell development that differ between tonsil and PP. The differential expression pattern of MAdCAM-1, together with the observation that ligation of beta(7) can inhibit the induction of CD38 expression, suggests that ligation of alpha(4)beta(7) in vivo may contribute to a PP-specific GC phenotype.     

Immunohistochemical identification of T- and B-lymphocytes delineated by the unlabelled antibody enzyme method

Summary T-lymphocytes and B-lymphocytes are identified in tissue sections of human tonsils by applying the unlabelled antibody enzyme method. The epithelium of the tonsils contains a majority of immunoglobulin-positive cells and fewer T-lymphocytes. In the subepithelial zones, areas composed of B-cells predominate, however, regions containing T-lymphocytes are also present. The latter are mainly arranged in the lamina propria around high-endothelial venules and often include plasma cells containing immunoglobulin. Follicles containing germinal centres display a complex structure which changes during development. The lymphocytic cap consists of densely packed lymphocytes, labelled heavily by anti-IgM and anti-IGD, and of individual T-lymphocytes. Germinal centres show a framework of immunoglobulin-positive dendritic reticular cells; they contain some heavily labelled lymphoid cells and several cells weakly labelled by anti-IgM and anti-IgA, as well as a small number of T-lymphocytes. Furthermore, the total areas of T- and B-lymphocytes measured by planimetry may differ considerably between different tonsils. Especially total areas of germinal centres vary to a great extent. The quantitative data on amounts of T- and B-cells achieved by planimetry are comparable to those reported in cellular suspensions of tonsils.     

Tonsil-derived mesenchymal progenitor cells acquire a follicular dendritic cell phenotype under cytokine stimulation

Tonsils comprise part of the mucosal immune system and contain lymphocytes, macrophages, and follicular dendritic cells (FDCs). FDCs are located in the B cell area of the follicles of secondary lymphoid organs, such as the spleen, tonsils, or lymph nodes, and they trap and retain immune complexes on their surfaces to regulate B cell activation and maturation. Stromal cells from the palatine tonsils are often used for FDC in vitro studies, and it has been reported that human palatine tonsils may be a good source of multipotent mesenchymal cells. Therefore, we assessed whether tonsil-derived mesenchymal stromal cells could differentiate into a FDC-like phenotype. We discovered that stromal cells isolated from human tonsils not only had the potential to differentiate into various cell types of mesenchymal origin, but they also could differentiate into FDC-like cells under cytokine stimulation in vitro.     

A new method for routine isolation of oral treponemes using U-tubes and pectin medium

Determination of the composition of the oral microflora has traditionally been based on cultivation. Treponemes are prevalent in many oral infections but, unfortunately, are not regularly cultured. In this study a new method was established for routine isolation of oral treponemes from clinical samples. Bacterial samples from 47 periodontal pockets and 4 endodontic infections were incubated anaerobically under nitrogen atmosphere at 37 degrees C in U-tubes containing pectin medium. In the U-tube a 'bacterial sample side' and a 'sterile medium side' were established on separate sides of a membrane filter and an agar plug. Using this method we were able to isolate viable treponemes from all bacterial samples. This was in contrast to previously established methods such as the agar dilution technique, the technique involving the membrane filter placed on the surface of solid agar media and the well in agar plate technique. We believe that the 'U-tube method' is a valuable supplement to previously described techniques in routine isolation of treponemes from clinical samples.     

The need for direct cell contact in "contact" inhibition of cell division in culture

Non-dividing mouse embryo fibroblasts which grew to a confluent cell density on one side of an ultra-thin filter did not inhibit the active multiplication of the same type of cells growing at low cell density on the other side of the filter directly opposite the confluent side. The close proximity of the cells across the filter was not sufficient to cause inhibition of cell division. The phenomenon of “contact” or “density dependent” inhibition of cell division is therefore probably not mediated by a cellular product which remains concentrated near the cell surface. The degree of contact inhibition of cell division was correlated with the local cell density on the same side of the filter. This relationship was found to be influenced strongly by the surface on which the cells were growing.