Search

IgG hybridomas monoclonal antibodies show that the cells of Candida albicans have a dynamic growth phase-specific expression of cell surface antigens. The cells express the 5C11 and 2E11 antigens throughout their growth and in young hyphae. The terminal regions of the longer hyphae express the 2G8 and 4E1 antigens within three hours of hyphae induction. Growth in a medium containing galactose delays the expression of 2G8 and 2E11. The 5C11 and 2E11 antigens are present between the 68 and 104 kDa bands in immunoblot analyses, while 4E1 and 2G8 are present between the 117 and 104 kDa bands.

The minor salivary gland network of the MRL/l mouse was investigated in a kinetic study and compared with the major submandibular gland. We report that minor salivary glands adopt two mutually exclusive patterns of inflammatory lesions depending on the gland. The first pattern is characteristic of human Sjogren's syndrome. It developed during the second month, affected 89% of the animals over 20 weeks old, and consisted of an accumulation of mononuclear cells around the duct system. Only the anterior buccal gland (ABG) showed this pattern, which is shared by the major salivary glands. The ratio of CD4+ to CD8+ cells was the same in lesions and in healthy tissue. No neutrophils were found in these lesions. The second pattern affected all the minor salivary glands except the ABG. These lesions were never observed before the age of 20 weeks and affected 38% of MRL/l mice between the ages of 10-32 weeks. In this pattern, neutrophils were frequently found, but mainly gathered at the periphery of the gland lobules. That a systemic immunoregulatory defect may be expressed as two different patterns of histopathology in the minor salivary glands suggest that the network behaves as a dichotomous entity depending on particular microenvironmental influences. [ABSTRACT FROM AUTHOR]

The oral manifestations of systemic autoimmunity were investigated in a kinetic study of the MRL/1 mouse. Lesions in the epithelium, connective tissue and minor salivary glands were characterized in serial sections of the soft palate and the cheeks with respect to 1) the type of inflammatory cells present, 2) the presence and type of vasculitis, 3) the presence of necrosis, 4) the occurrence of deposits. By the age of 16 wk, 100% of our animals had developed mild to severe lesions in at least one compartment of the mucosa. Between 16 and 32 wk of age, pathologic manifestations affected the epithelial and subepithelial tissues, the striated muscle tissue, the vascular system and, much less frequently, the minor salivary gland network. [ABSTRACT FROM AUTHOR]

A model of oral candidosis was developed in order to investigate histologic and microbiologic aspects of this host-parasite interaction under controlled experimental conditions. Normal adult CD-1 mice were inoculated by the topical application of 10(8) Candida albicans blastospores, and oral colonization was monitored by the quantitative culturing of saliva samples and of digested oral mucosa. Tissue sections of the mucosa were examined in a kinetic study ranging from 2 h to 13 days postinoculation. We report here that oral colonization by C. albicans can be induced in normal adult mice without the use of any compromising agent and that the animals recover from this mucosal infection following a reproducible pattern. Temporal analysis of the oral histopathology showed that distinct patterns of inflammation are associated with particular stages in the development of the infectious foci. This experimental model offers a means of further investigating the host-parasite interactions involved in the onset and development of oral candidosis. [ABSTRACT FROM AUTHOR]

We used an experimental model of oral candidiasis in the mouse to investigate the impact of the introduction of Candida albicans into a Candida-free system. We report that 2 strains of mice with the same major histocompatibility complex haplotype (H-2d) display different kinetics of primary oral infection after topical application of the same inoculum. The mucosal reactions in both DBA/2 and BALB/c mice involve a similar recruitment of CD4+ and CD8+ T cells and of MAC-1+ cells in mucosal tissue during the infection. A carrier state is maintained following the resolution of the infection in both strains and is associated with the persistence of intraepithelial CD4+ T cells. However, there is a time-specific recruitment of γδ T cells that coincides with a dramatic decrease in viable Candida in the mucosal tissue; this occurs on day 3 in BALB/c mice and on day 6 in DBA/2 mice. The denouement of an oral contact with Candida is also different in the 2 mouse strains, cell-mediated immunity being triggered in DBA/2 mice but not in BALB/c mice. The different kinetics of Candida clearance in BALB/c vs DBA/2 mice may therefore signal a differential priming of T cell subsets whose modalities do not appear to be associated with the H-2 complex. [ABSTRACT FROM AUTHOR]

In our experimental model of oral candiasis in the CDI mouse, the primary infection showed reproducible Candida overgrowth kinetics with a peak level on day 5 of the infection. After day 7, the population stabilized at about 300 colony-forming units per excised mucosal tissue. The primary infection triggered an inflammatory response that resolved in under 8 days. At this point, the histological pattern of the mucosa reached a new equilibrium between recruited and resident mononuclear cells. The primary infection also rapidly stimulated cellular immunity, as measured from day 4 by a delayed-type hypersensitivity footpad reaction, Following a second topical challenge with Candida 30 days after the primary infection, the infection was barely detectable and a typical local delayed-type hypersensitivity reaction occurred between 24-72 h. It is proposed that acquired resistance, in conjunction with low-level persistence of Candida in our model, mimics the carrier state in sensitized humans. [ABSTRACT FROM AUTHOR]

Necrotic enteritis (NE) is a poultry intestinal disease caused by virulent strains of the bacterium Clostridium perfringens (C. perfringens). This anaerobic bacterium produces a wide range of enzymes and toxins in the gut which leads to NE development. It is generally accepted by the poultry veterinarians that netB-positive C. perfringens strains are virulent and netB-negative strains do not cause NE. However, NE pathogenesis remains unclear as contradictory results have been reported. The use of experimental in vivo models is a valuable tool to understand the pathogenesis of a disease. In this study, a chicken ligated loop model was used to determine the virulence status of 79 C. perfringens strains from various geographical locations, sources, and genotype profiles. According to our model and based on histologic lesion scoring, 9 C. perfringens strains were classified as commensal, 35 as virulent, and 34 as highly virulent. The virulence of only 1 C. perfringens strain could not be classified as its lesion score was variable (from <10 to >15). In general, NE lesions were more severe in intestinal loops inoculated with netB-positive C. perfringens strains than those inoculated with netB-negative strains. The prevalence of netB among strains classified as commensal, virulent, and highly virulent was 56% (5/9), 54%, (19/35), and 59% (20/34). These results suggest that NetB is not required to cause NE lesions and that other factors are also involved. The classification of the virulence status of C. perfringens strains should not be based solely on the presence or absence of this toxin. Therefore, the use of an in vivo model is essential to distinguish commensal from virulent strains of C. perfringens., (Copyright © 2024. Published by Elsevier Inc.)

Vaccination against bacteria offers its share of challenges, and important progress has been made in recent years. Conventional vaccinology has protected poultry for decades with killed and attenuated bacterial vaccines. Because of the limitations of these vaccines, and given the latest technological advances, other types of vaccines were developed using various strategies. New vaccines are also being commercialized using viral or bacterial recombinant vectors or in the form of subunit vaccines developed by a genomic approach and bioinformatics analyses. As bacteria are forever-evolving microorganisms, there is no doubt that vaccine strategies preventing bacterial diseases will also evolve and that new generations of vaccines are yet to come.

In rural sub-Saharan Africa, preventable delays in accessing emergency care remain a dominant factor in maternal and neonatal deaths. The MOMENTUM study is a pragmatic cohort investigation designed to measure the "Three Delays", i.e. delays in recognizing need for care (Type 1), reaching care (Type 2), and receiving care (Type 3) within a remote island health system on Lake Victoria, Kenya. The study utilizes an adaptive methodology to provide actionable data for a locally-directed "Health Navigation" intervention. We present analysis of 56 maternal and neonatal emergency cases occurring between January 2019 and February 2020. The mean Total Delay Interval (Type 1-3) reported was 39.3 ± 32.3hours. Notably, 18 cases in this cohort resulted in a neonatal ( n  = 16) or maternal death ( n  = 2). Sub-analysis indicates significant delay interval reductions associated with involvement of a "Health Navigator" in emergency care coordination for Type 2 Delay Intervals (0.5 ± 0.3 vs. 1.2 ±  1.1 hrs., p  = 0.002) and Type 3 Delay Intervals (17.9 ± 14.1 vs. 32.9 ± 33.7 hrs., p  = 0.030). Prolonged delays, complex barriers, and high mortality highlight the fraught nature of maternal emergencies in this remote setting. We discuss practical considerations for application of the Three Delays model, and avenues for further investigation.

Tracheostomy is sometimes required for long-term ventilation in patients with a challenging cervical anatomy. We present a case of a patient requiring prolonged mechanical ventilation with prohibitive cervical anatomy for standard tracheostomy secondary to severe ankylosing spondylitis and a cervical spine fracture., (2010 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.)

Statement of Problem: The adhesion of microorganisms to a denture surface can result in denture stomatitis., Purpose: The purpose of this study was to evaluate denture biofilm in vivo using a new sampling system to gain a better understanding of plaque organization in Candida-induced denture stomatitis. Removable acrylic resin disks were used with self-adhesive paper disks to compare biofilm formation and retention efficacy of both sampling systems., Material and Methods: Twenty-one subjects with a complete maxillary denture were recruited, 12 with a clinical diagnosis of chronic denture stomatitis and 9 with a clinically healthy palatal mucosa. A custom-made autopolymerized 3.0-mm-diameter acrylic resin disk inlay was inserted in a cavity prepared within the intaglio surface of the maxillary denture in contact with either normal or inflamed mucosa. Next to the acrylic resin disk, a self-adhesive paper disk was placed for comparison of the 2 sampling techniques. Denture biofilms were collected within variable time periods of 1 hour to several months, and descriptive data were provided by means of scanning electron microscopy analyses. The method of retention and recovery of specimen disks were evaluated between both sampling techniques using a chi-square test to assess significant differences (alpha=.05)., Results: Early event features of denture biofilms showed differences in biofilm organization between the 2 sampling techniques but became subtler with increased time periods. Regardless of the sampling technique, interparticipant variations could be observed as to rate, microorganism density, and architectural pattern. In general, denture biofilm formation was increased when the sampling disks were localized in areas affected by denture stomatitis., Conclusion: The new sampling technique provides reliable information with controlled formation time of denture biofilm in its natural environment.

Objective: The aim of this study was to reevaluate the link between Candida albicans and denture-related stomatitis according to a modified Newton classification, which reflects the classic types of inflammation as well as the extent to which the tissue is affected., Study Design: Two groups of denture wearers were evaluated for denture-related stomatitis. The presence and number of yeasts on the dentures, the identification of the Candida species present, and the amount of plaque coverage were determined. Putative risk factors were included in the study. Relations between these variables and stomatitis were analyzed statistically., Results: According to Newton's classification, the presence of yeast on the denture was not linked to whether subjects had stomatitis. But with our classification, higher prevalence of yeast carriers, yeast colony number, and plaque coverage were found on the dentures of individuals with the most extensive inflammation, regardless of Newton type. Among risk factors evaluated, wearing dentures at night and smoking were associated with the most extensive inflammation. We also demonstrated that the presence of C albicans as well as the cohabitation of different Candida species was more frequent in denture-related stomatitis. The differences were statistically significant., Conclusions: Statistical analysis of microbiologic data from different denture-related stomatitis categories according to our modified classification showed that the presence of yeast on dentures was significantly associated with the extent of the inflammation, rather than with the Newton type. Our findings suggest that the inflammatory process of stomatitis favors the colonization of Candida. These results could have new implications for diagnosis and management of the condition.

The role of epithelial cells in oral pathologies is poorly understood. Until now, most studies have used normal or transformed epithelial cell monolayers, a system that largely bypasses oral mucosal complexity. To overcome these limitations, an engineered human oral mucosa (EHOM) model has been produced and characterized. Following histological and immunohistochemical analyses, EHOM showed well-organized and stratified tissues in which epithelial cells expressed proliferating keratins such as Ki-67, K14, and K19 and also differentiating keratin (K10). In this model, epithelial cells interacted with fibroblasts in the lamina propria by secreting basement membrane proteins (laminins) and by expressing integrins (beta1 and alpha2beta1). Cytokine analyses using cultured supernatants showed that cells in EHOM were able to secrete interleukins (IL) including IL-1beta and IL-8 and tumor necrosis factor alpha (TNF-alpha). Finally, cells in this engineered model were able to secrete different metalloproteinases such as gelatinase-A and gelatinase-B. In conclusion, using tissue engineering technology, we produced well-organized EHOM tissues. It is anticipated that this model will be useful for examining mechanisms involved in oral diseases under controlled conditions by modeling the interactions between mucosa and microorganisms in the oral cavity.

We report here that in addition to a cytoplasmic copper-zinc-containing superoxide dismutase (SOD) and a mitochondrial manganese-containing SOD, Candida albicans expresses a third SOD gene (SOD3). The deduced amino acid sequence contains all of the motifs found in previously characterized manganese-containing SODs, except the presence of a mitochondrial transit peptide. Recombinant Sod3p expressed and purified from Escherichia coli is a homotetramer with a subunit mass of 25.4 kDa. Mass absorption spectrometry detected the presence of both iron and manganese in purified Sod3p but, as determined by metal replacement experiments, the enzyme displays activity only when bound to manganese. Overexpression of SOD3 was shown to rescue the hypersensitivity to redox cycling agents of a Saccharomyces cerevisiae mutant lacking the cytoplasmic copper-zinc-containing SOD. Northern blot analyses showed that the transcription of SOD3 is induced neither by the transition from the yeast to the mycelial form of C. albicans nor by drug-induced oxidative stress. In continuous cultures, the expression of SOD3 was strongly stimulated upon the entry and during the stationary phase, concomitantly with the repression of SOD1. We conclude that Sod3p is an atypical cytosolic manganese-containing superoxide dismutase that is involved in the protection of C. albicans against reactive oxygen species during the stationary phase.

Persistent B-cell lymphocytosis (PPBL) is a haematological disorder diagnosed primarily in adult female smokers that is characterized by a polyclonal increase in peripheral blood B lymphocytes and a moderate elevation of serum IgM. B lymphocyte-associated cellular abnormalities, such as the occurrence of multi-lobed nuclei, increased bcl2/Ig gene rearrangements and the identification of an extra long-arm chromosome (i3)(q10) in the B-cell population, indicate that PPBL could be part of a multi-step process leading to the emergence of a malignant B lymphoproliferation. However, the resulting impact on cellular functional properties remains to be elucidated. Our goal was to address that aspect via the study of B-cell activity following stimulation through CD40, a key molecule of the tumour necrosis factor receptor superfamily involved in B lymphocyte development. In contrast to normal B cells, PPBL B lymphocytes were unable to respond to the proliferative signal delivered in vitro by CD40, indicating a defect in the CD40 activation pathway. Polymerase chain reaction amplification and sequencing of the receptor as well as FACScan analysis of patient B lymphocytes dismissed the possibility of a defect in either CD40 structure or expression. Moreover, Western blot analysis of tyrosine phosphorylation, an early event in the CD40-signalling cascade, was similar in patients and controls, leading to the conclusion that the defect affecting B lymphocytes in PPBL patients is probably located downstream of that signalling cascade.

Objectives: The aim was to evaluate the effectiveness of a preventive oral health program on the prevalence of oral candidosis in 237 frail or dependent residents in a long-term care facility. Half of the residents were included in an experimental group which benefited from a preventive oral hygiene program including instruction of the carers and implementation of a recall program for professional oral hygiene care., Methods: Intraoral examinations and yeast cultures from the oral mucosa and the fitting denture surface were carried out at baseline and 18 months later. The outgrowth of yeast was estimated on Oricult-N dip slides using the scale: no growth; 1-20 colonies; 21-100 colonies; >100 colonies., Results: At baseline (n = 237) and at 18 months (n = 159) the experimental and the control groups were similar with regard to the residents' distribution by age, sex, dental and prosthetic status and prevalence of denture stomatitis. The 78 residents lost had the same baseline characteristics as the survivors, except for being older. In the experimental group the severity of the inflammation of the palate decreased (P = 0.005) as well as the prevalence of glossitis (P = 0.005). At baseline high yeast scores from the mucosa (>20) were observed in about 50% of the residents in the experimental as well as the control group. At 18 months this figure was 23.4% for the experimental and 48.7% for the control group (P = 0.001). There was also a reduction of the number of residents with positive cultures and the denture yeast scores at 18 months in the experimental group (P = 0.05)., Conclusions: This study has shown that the preventive program was effective in reducing the colonization of the oral mucosa and dentures by Candida and thereby improving the health of the oral mucosa.

The mycelial surface antigen recognized by monoclonal antibody (mAb) 4E1 has previously been shown to be present predominantly in the terminal third of the hyphal structures in Candida albicans. We report here the expression cloning of the corresponding gene (CSA1 ) by mAb 4E1-coated magnetic beads sorting of Saccharomyces cerevisiae transformants expressing a C. albicans genomic library. The strategy is both highly selective and highly sensitive and provides an additional genetic tool for the cloning and characterization of C. albicans genes encoding surface proteins. CSA1 is an intronless gene encoding a 1203-residue protein composed of repetitive motifs and domains. Northern analysis indicates that CSA1 is preferentially expressed during the mycelial growth phase, although a low level of CSA1 mRNA can be detected in the yeast form. As evidenced by indirect immunofluorescence microscopy with mAb 4E1, Csa1p is not randomly distributed over the surface of yeast cells, but localizes predominantly in the growing buds. This suggests that the distribution of Csa1p may be restricted to sites of cell surface elongation. Both heterozygous and homozygous C. albicans csa1Delta mutants are viable. Upon induction of mycelial growth, the number and size of hyphal structures derived from the mutants are similar to those observed in the parental wild-type strain. The physiological role of Csa1p has yet to be determined. However, the presence in Csa1p of repeated cysteine-rich hydrophobic domains with significant sequence similarity to motifs found in surface proteins (Ag2 and Pth11) from two distantly related fungal pathogens (Coccidioides immitis and Magnaporthe grisea respectively) suggests a common function in host interaction.

We used an experimental model of oral candidiasis in the mouse to investigate the impact of the introduction of Candida albicans into a Candida-free system. We report that 2 strains of mice with the same major histocompatibility complex haplotype (H-2d) display different kinetics of primary oral infection after topical application of the same inoculum. The mucosal reactions in both DBA/2 and BALB/c mice involve a similar recruitment of CD4+ and CD8+ T cells and of MAC-1+ cells in mucosal tissue during the infection. A carrier state is maintained following the resolution of the infection in both strains and is associated with the persistence of intraepithelial CD4+ T cells. However, there is a time-specific recruitment of gamma delta T cells that coincides with a dramatic decrease in viable Candida in the mucosal tissue; this occurs on day 3 in BALB/c mice and on day 6 in DBA/2 mice. The denouement of an oral contact with Candida is also different in the 2 mouse strains, cell-mediated immunity being triggered in DBA/2 mice but not in BALB/c mice. The different kinetics of Candida clearance in BALB/c vs DBA/2 mice may therefore signal a differential priming of T cell subsets whose modalities do not appear to be associated with the H-2 complex.

The effect of sera collected from either pigs or dogs previously fed a vitamin E (vit E)- and selenium (Se)-deficient diet on in vitro lymphocyte blastogenesis response to mitogens was studied. Porcine sera were obtained from pigs used in 2 different trials. In I trial, 4-wk-old pigs received either a basal diet deficient in vit E and Se or the basal diet supplemented with Vit E, Se or Vit E and Se. Pigs were maintained on their respective diet for 25 d. Canine sera were collected from pups maintained on a deficient diet for 8 wk. Four dogs and 4 pigs maintained on a commercial diet were used as donors of peripheral blood lymphocytes (PBL). The addition of sera from pigs or dogs maintained on a vit E- and Se-deficient diet markedly suppressed both porcine and canine PBL response to mitogens. Porcine PBL blastogenesis was also suppressed when porcine or canine sera were added 8, 24 or 48 h after the beginning of the incubation period to culture containing 1% of fetal bovine serum (FBS). However, the suppressive effect caused by porcine sera was less severe than the one due to canine sera. Addition of 1% FBS in the cultures was sufficient to eliminate the suppression caused by the presence of sera from pigs fed a vit E- and Se-deficient diet. Other attempts to restore the lymphocyte response to mitogens by the addition of indomethacin, diethylcarbamazine or eicosatetraynoic acid, inhibitors of prostaglandin and/or leukotriene synthesis, were not successful. Because of the severe suppression caused by sera from animals maintained on a vit E- and Se-deficient diet on the in vitro response of lymphocytes to mitogenic stimulations, it is very important to take precautions to avoid such deficiency. In vivo suppression of immunocompetent cells to antigenic stimulations may impair the capacity of the host to control infections.