The periodontal pocket: pathogenesis, histopathology and consequences.

The conversion of junctional epithelium to pocket epithelium is regarded as a hallmark in the development of periodontitis. Knowledge of factors contributing to the initiation and progression of pocket formation is important and may result in the development of better preventive measures and improve healing outcomes after therapeutic interventions. The periodontal pocket is a pathologically deepened gingival sulcus. In healthy periodontal conditions, the defense mechanisms are generally sufficient to control the constant microbiological challenge through a normally functioning junctional epithelium and the concentrated powerful mass of inflammatory and immune cells and macromolecules transmigrating through this epithelium. In contrast, destruction of the structural integrity of the junctional epithelium, which includes disruption of cell-to-cell contacts and detachment from the tooth surface, consequently leading to pocket formation, disequilibrates this delicate defense system. Deepening of the pocket apically, and also horizontal expansion of the biofilm on the tooth root, puts this system to a grueling test. There is no more this powerful concentration of defense cells and macromolecules that are discharged at the sulcus bottom and that face a relatively small biofilm surface in the gingival sulcus. In a pocket situation, the defense cells and the macromolecules are directly discharged into the periodontal pocket and the majority of epithelial cells directly face the biofilm. The thinning of the epithelium and its ulceration increase the chance for invasion of microorganisms and their products into the soft connective tissue and this aggravates the situation. Depending on the severity and duration of disease, a vicious circle may develop in the pocket environment, which is difficult or impossible to break without therapeutic intervention.

[Fungal invasion of connective tissue in patients with gingival-periodontal disease]. / Invasión fúngica en tejido conectivo en pacientes con enfermedad gingivo-periodontal.

BACKGROUND: In the last few years unusual microorganisms have been isolated from subgingival biofilm, as possible initiators or contributors to periodontal disease, especially in patients who show no improvement during treatment. AIMS: To study the Candida invasion of the connective tissue in relation to subgingival biofilm presence. METHODS: A total of 55 immunocompetent patients of both sexes, between 21 and 55 years of age, non-smokers, without previous antimicrobial treatment, suffering periodontal diseases, were studied. Soft tissues, supragingival and subgingival plaque samples, and periodontal pocket biopsies were taken. Microscopic studies, cultures, assimilation profiles, and DNA amplifications were performed. RESULTS: In 35% of the samples, different species of Candida were isolated in cultures, especially Candida albicans. Hyphae invasions in the connective tissue were observed, in association with anaerobic microorganisms (Porphyromonas gingivalis, Prevotella intermedia and Aggregatibacter actinomycetemcomitans) in patients with periodontitis. CONCLUSIONS: Different species of Candida could be part of the periodontal plaque and could play an important role in the adherence to soft tissues, allowing deep invasion. They also could infect gingival pockets in patients with gingivitis, even in healthy locations, playing a commensal or opportunist role.

Quantification and location of Chlamydia pneumoniae-specific antigen in the walls of abdominal aortic aneurysms.

BACKGROUND: To evaluate the prevalence and quantity of Chlamydia pneumoniae-specific antigen in the three layers (intima, media, and adventitia) of abdominal aortic aneurysms (AAAs), so as to further investigate the pathogenesis of AAAs. METHODS: Aortic walls were collected from 20 patients with AAA and 11 healthy organ donors. Immunohistochemistry was used to identify the C pneumoniae-specific antigen, and image analysis system was used to quantify and locate it. RESULTS: The positive rate of C pneumoniae-specific antigen was higher in the AAA group than in the control group (100% vs. 54.54%, p = 0.003), positive intensity decreased from the tunica intima to the adventitia in the AAA group (16.32% ± 2.13%, 14.84% ± 1.80%, and 14.25% ± 1.67%, respectively, p = 0.003). In the control group, positive cells were mainly found in focal lesion areas. CONCLUSION: We have demonstrated the presence and differentiation of C pneumoniae-specific antigen in the three layers of AAAs, which are in accordance with pathology, thus suggesting a pathogenic role of the antigen.

Severe musculoskeletal infection variant in Lemierre's syndrome.

Lemierre's syndrome is a severe complication of Fusobacterium necrophorum oropharyngeal infection associated with metastatic foci of infection, internal jugular vein thrombosis, and septicemia. Musculoskeletal manifestations include isolated or multifocal septic arthritis, soft tissue abscesses, pyomyositis, and osteomyelitis. This article describes a case of a variant of Lemierre's syndrome in a 17-year-old girl, demonstrating a relentless case of limb infection refractory to multiple surgical debridements and broad-spectrum and targeted antibiotics. The patient had F. necrophorum within a peritonsillar abscess and multiple foci within her right lower extremity. Overall, she required 12 surgical procedures and 14 weeks of antibiotic therapy to resolve the infection. Further unique findings in this case include the presence of a recent lateral meniscus tear with associated hemarthrosis treated with a short course of oral steroids prior to the diagnosis of septic arthritis. Knee arthroscopy with lysis of adhesions and manipulation at 6 months postinfection demonstrated significant chondral damage. Outcome at >2-year follow-up revealed pain-free activities of daily living and the ability to return to competitive, club-level collegiate softball. Clinically relevant findings illustrated in this case include potential development of antibiotic resistance within Fusobacterium genus with little to no response to several surgical debridements and broad-spectrum and targeted antibiotics, and development of multifocal, ipsilateral septic arthritis and soft tissue abscesses and pyomyositis in the context of steroid use and recent intra-articular knee injury.

Normal human gingival epithelial cells sense C. parapsilosis by toll-like receptors and module its pathogenesis through antimicrobial peptides and proinflammatory cytokines.

This study was designed to investigate the interaction between C. parapsilosis and human epithelial cells using monolayer cultures and an engineered human oral mucosa (EHOM). C. parapsilosis was able to adhere to gingival epithelial cells and to adopt the hyphal form in the presence of serum. Interestingly, when cultured onto the engineered human oral mucosa (EHOM), C. parapsilosis formed small biofilm and invaded the connective tissue. Following contact with C. parapsilosis, normal human gingival epithelial cells expressed high levels of Toll-like receptors (TLR)-2, -4, and -6, but not TLR-9 mRNA. The upregulation of TLRs was paralleled by an increase of IL-1beta, TNFalpha, and IFNgamma mRNA expression, suggesting the involvement of these cytokines in the defense against infection with C. parapsilosis. The active role of epithelial cells in the innate immunity against C. parapsilosis infection was enhanced by their capacity to express high levels of human beta-defensin-1, -2, and -3. The upregulation of proinflammatory cytokines and antimicrobial peptide expression may explain the growth inhibition of C. parapsilosis by the gingival epithelial cells. Overall results provide additional evidence of the involvement of epithelial cells in the innate immunity against C. parapsilosis infections.

Experimental evidence supports the abscess theory of development of radicular cysts.

OBJECTIVE: The objective of this study was to experimentally induce inflammatory cysts in an animal model so as to test the hypothesis that radicular cysts develop via the "abscess pathway." METHODOLOGY: Twenty-eight perforated custom-made Teflon cages were surgically implanted into defined locations in the back of 7 Sprague Dawley rats. A week after the implantation of the cages, a known quantity of freshly grown, close allogeneic oral keratinocytes in phosphate buffer solution (PBS) was injected into each cage. One cage per animal was treated as the control that received only epithelial cells. The remaining 3 cages of each animal were trials. Seven days post epithelial cell inoculation; a suspension of 0.2 mL of Fusobacterium nucleatum (10(8) bacteria per mL) was injected into each of the 3 trial cages. Two, 12, and 24 weeks after the inoculation of the bacteria, the cages were taken out, and the tissue contents were fixed and processed by correlative light and transmission electron microscopy. Sixteen of the 21 trial cages could be processed and yielded results. RESULTS: Inoculations of epithelial cells followed 1 week later by F. nucleatum into tissue cages resulted in the development inflammatory cysts in 2 of the 16 cages. The 2 cages contained a total of 4 cystic sites. None of the control cages showed the presence of any cyst-like pathology. CONCLUSIONS: Inflammatory cysts were induced by initiating acute inflammatory foci (abscess/necrotic area) by bacterial injection that got enclosed by a proliferating epithelium. This finding provides strong experimental evidence in support of the "abscess theory" of development of radicular cysts.

Soluble antagonists to interleukin-1 (IL-1) and tumor necrosis factor (TNF) inhibits loss of tissue attachment in experimental periodontitis.

BACKGROUND, AIMS: Periodontal disease is a significant cause of tooth loss among adults and is characterized by the alteration and permanent destruction of the deeper periodontal tissues. Although the presence of pathologic microbes is required to trigger this process, the amplification and progression of the diseased state is believed to rely heavily on the production of host mediators in response to bacteria or their metabolic products. The inflammatory response is effective in preventing large-scale colonization of the gingival tissues by bacteria that lie in close proximity to the tooth surface or within the gingival sulcus. It has been postulated that the host-response in some individuals may lead to an over-reaction to invading oral pathogens resulting in the destruction of periodontal tissues. METHODS: Several host-derived mediators are believed to contribute to this response. Two agents considered to be essential in periodontal destruction are interleukin-1 (IL-1) and tumor necrosis factor (TNF). We investigated the role of IL-1 and TNF in the loss of connective tissue attachment in a Macaca fascicularis primate model of experimental periodontitis. Silk ligatures impregnated with the periodontal pathogen, Porphyromonas gingivalis were wrapped around the posterior teeth and the activity of IL-1 and TNF were inhibited by soluble receptors to these proinflammatory cytokines via local injection into interdental papillae. RESULTS: Histomorphometric analysis indicates that IL-1 and TNF antagonists significantly reduced the loss of connective tissue attachment by approximately 51% and the loss of alveolar bone height by almost 91%, both of which were statistically significant. CONCLUSION: This investigation demonstrates that the loss of connective tissue attachment and progression of periodontal disease can be retarded by antagonists to specific host mediators such as IL-1 and TNF and may provide a potential treatment modality to combat the disease process.

Field emission scanning electron microscopy study of the mouse lingual mucosa, with special reference to adhesion of bacteria in the epithelial cell membranes

The dorsal surface of three-day postnatal mouse tongue was examined by field emission scanning electron microscope and revealed that the fungiform papillae are round in shape and filiform papillae present small projection in development. The surface of interface of epithelium-connective tissue showed small projections of papilla corresponding to the filiform and fungiform papillae. The surfaces of epithelial cell membranes present numerous microplicae with adhesion of streptococcus. These bacteria are attached on the cell membrane in organized rows of rat random, demonstrating their three-dimensional FESEM images. At high magnification, on ther surface of each bacteria may be noted small particles.

Necrotizing fasciitis originating from pinna perichondritis.

NF is a potentially lethal infectious process usually found in the abdomen, perineum, or extremities. In the head and neck it usually starts from a dental infection but can be initiated from any source. One of the more serious sequelae is extension of the infection down the deep fascial planes of the neck leading to mediastinitis; this is associated with a higher mortality rate. The presence of an associated immunocompromising disease, such as diabetes, has been said to predispose an individual to NF, and the mortality rate has been shown to be higher (although perhaps not significantly so). When first described, NF was thought to be caused only by beta-hemolytic Staphylococcus. Now it known to be a polymicrobial infection with anaerobes and facultative anaerobes found most frequently. Treatment involves broad-spectrum intravenous antibiotics as soon as possible, narrowing the coverage as the results of the gram stain and cultures become available. The importance of aggressive, prompt surgical management cannot be overemphasized in the treatment of NF. Once the diagnosis of NF is strongly suspected, debridement of the affected areas must be accomplished as soon as possible. Despite the advances in the recognition and treatment of NF, there is still significant morbidity and mortality associated with this disease. Continued vigilance must be practiced if the survival rate is to continue to increase.

Pseudomembranous oral candidiasis in HIV infection: ultrastructural findings.

A light and electron microscopic investigation of pseudomembranous candidiasis in HIV infection was undertaken as there is little data available on the ultrastructural features of the invasive phase of Candida in this disease. On examination of biopsy specimens of four patients, histopathology revealed the classic features of superficial candidiasis, including hyphal penetration down to the spinous cell layer, parakeratosis, acanthosis and spongiosis of the infected, superficial epithelium. However, in one case, hyphae traversed the entire epithelium and crossed the basal membrane, invading the adjacent connective tissue. Ultrastructural investigations revealed initial hyphal penetration through the intercellular spaces, possibly demonstrating thigmotropism. However, hyphal penetration was not solely confined to intercellular spaces, as some specimens demonstrated hyphal elements traversing both the cytoplasm and the nuclei of the spinous cells. In these areas of the epithelium appressoria-like appendages were often found at the hyphal tip. These phenomena, commonly described in plant fungi, have rarely been described in human material. Pools of desmosomes were seen in the vicinity of the hyphal pathways, implying that the penetration procedure is associated with detachment and congregation of desmosomes, possibly by enzymatic means. Interestingly, the host immune response to fungal invasion appeared to be minimal, as no immune-effector cells were seen closely associated with either the blastospores or the hyphae in any of the tissues examined. Whether the foregoing events are exaggerated by the abortive immune response seen in HIV-infected patients, or common in immunocompetent individuals during candidal invasion of epithelia, needs to be ascertained by further studies.

Retroviral transmission by the transplantation of connective-tissue allografts. An experimental study.

The transmission of a retrovirus by the transplantation of allografts of connective tissues was studied in a feline model with use of the feline leukemia virus, a retrovirus with a replication cycle and pathological characteristics similar to those of the human immunodeficiency virus. The retrovirus was used to infect four specific-pathogen-free cats that were subsequently used as tissue donors. Fresh allografts of menisci, patellar ligaments, and patellar ligament and bone composites were harvested from infected donors and were transplanted into the knee joints of twelve specific-pathogen-free cats. A fresh cancellous-bone allograft was transplanted into the proximal part of the tibia of four additional specific-pathogen-free cats, which served as positive control animals. Additional grafts from infected donors were harvested and were stored at -80 degrees Celsius for ten weeks. A fresh-frozen graft was then transplanted into the knee of twelve other specific-pathogen-free cats. Samples of plasma were obtained weekly from all twenty-eight cats and were tested with both an enzyme-linked immunosorbent assay to detect the presence of viral antigen and an immunofluorescent antibody assay to determine exposure to the virus. All types of fresh and fresh-frozen connective-tissue allografts from the infected donors resulted in transmission of the retrovirus to the recipient cats. The recipients had evidence of viral antigen or rising antibody titers as early as two weeks after the transplantation. Histological examination of specimens of the allografts revealed normal incorporation of the transplanted tissues, with no sign of rejection of the graft.

The secretory cells of mouse salivary glands are nonpermissive for polyomavirus replication.

Parotid tumor agent was an early name for polyomavirus due to its ability to induce tumors (myoepitheliomas originating from the myoepithelial glandular tissues) in mice inoculated with polyomavirus (Py) as neonates. It has long been thought that these tumors directly follow productive infection by Py in epithelial cells of the salivary gland, allowing subsequent cellular genetic changes leading to tumor formation. Curiously, the ability of salivary glandular tissue to support Py infection has not been experimentally established. Although Southern analysis for Py DNA has shown virus DNA to be present in whole salivary glands during acute infection, salivary glands are composed of various cell types (myoepithelial glandular cells called serous and mucous cells, fibrocollagenous cells, and interstitial cells), not all of which become transformed. We now use in situ hybridization for Py DNA along with immunohistological and immunohistochemical analyses to show that salivary gland serous and mucous cells are nonpermissive for acute Py infection in Balb/C and C3H mice, but are Py infected, as shown by T-ag expression. Salivary gland fibroblasts and interstitial cells, however, were permissive for Py replication. In addition, isoproterenol and tannin, which induce hypertrophy and hyperplasia of the secretory cells of adult male mice salivary glands, did not make these cells permissive to Py replication.

Implantes y periodoncia / Dental implants and periodontics

Se evaluará la estrecha relación entre implantes y tejidos periimplantarios. Se indicará cómo prevenir patología en esa área o bien cómo tratarlas cuando se han producido

Systemic dissemination by a newly recognized intestinal microsporidia species in AIDS.

OBJECTIVE: Primarily to determine whether an intestinal microsporidian recently identified in AIDS patients disseminates from the bowel to infect other organs. DESIGN: Disseminated microsporidiosis has been reported in immunocompromised humans, but never due to Enterocytozoon bieneusi, the most common species in AIDS patients and one that evidently infects only enterocytes. In animals, dissemination follows ingestion of Encephalitozoon cuniculi spores, apparently via macrophages, and pathology occurs in, for example, kidneys and brain. A second, un-named Encephalitozoon-like intestinal microsporidia has been identified in five AIDS patients with chronic diarrhea; because it infects lamina propria macrophages, it was logical to investigate its dissemination. METHODS: Light and transmission electron microscopy were used to study urine sediment from four out of five patients with biopsy-documented small intestinal infection due to the second intestinal microsporidian. The gall bladder from one patient and autopsy specimens from an E. bieneusi-infected patient were similarly studied. RESULTS: Systemic dissemination was documented by detecting abundant spores, both free and within renal tubular and transitional cells, in the urine of two patients. Many of the lamina propria macrophages in these two patients' intestinal biopsies contained microsporidia, while those of the two negative patients either contained only Mycobacterium avium complex or only occasional parasites. The gall bladder was co-infected with this microspordian and with cytomegalovirus. At autopsy, the patient with documented enteritis due to E. bieneusi 2 years before death had disseminated microsporidiosis, not of E. bieneusi, but apparently of the second intestinal species. The microsporidian had caused severe tubulointerstitial nephritis. Parasites were also observed in non-parenchymal cells of the liver and bronchial epithelium. CONCLUSION: A newly described Encephalitozoon-like intestinal microsporidian, which causes chronic diarrhea in AIDS patients, can disseminate and cause renal pathology.

Persistence of selectable herpesvirus saimiri in various human haematopoietic and epithelial cell lines.

Herpesvirus (h.) saimiri, an infectious agent of squirrel monkeys, is capable of persisting in T lymphocytes of various primate species. It has been used as a vector for the functional analysis of regulatory genes in primary human T lymphocytes. As it is not yet known whether other cell types are capable of supporting viral persistence, various human cell lines were investigated using selectable h. saimiri recombinants. The lines chosen represent cells from the epithelium and connective tissue as well as from all haematopoietic lineages, i.e. cells of B and T lymphoid origin as well as myeloid-, fibroblast- and carcinoma-derived cultures converted to Geneticin or hygromycin B resistance, and harbouring episomal DNA of the selectable recombinants. The Burkitt's lymphoma-derived cell line Raji also contained simultaneously persisting episomes of the Epstein-Barr virus. Most of the cell cultures except a pancreatic carcinoma line and foreskin fibroblasts did not produce infectious virus. These observations show that a herpesvirus genome can persist episomally in a broad range of cultured cell types. The variety of infectable cell types and species suggests the presence of a widely distributed and well conserved virus receptor for h. saimiri. Thus the h. saimiri genome could be applied more generally as a vector.

Bacterial penetration of gingiva in the adult beagle dog with periodontitis.

Invasion of gingival tissues by bacteria is thought to be a major factor in development of periodontal lesions. Morphologic studies have revealed bacteria within the pocket epithelium, gingival connective tissues, alveolar bone, and oral epithelium. The current studies are intended to determine whether they are present in healthy and diseased tissues and to identify the microbial source. Five beagle dogs with naturally occurring periodontitis were fed a soft diet. Two quadrants of the dentition of each dog were cleaned regularly and health maintained while others were allowed to develop further disease. After 4 weeks, samples of gingiva were removed both prior to and after the animals were sacrificed by perfusion fixation attempting not to introduce microorganisms. The identical samples were examined by light and scanning electron microscopy for numbers and location of organisms. Their numbers were greater in diseased than in healthy tissues. Furthermore, the quantity was greater in samples taken prior to perfusion fixation than after such treatment, especially in the oral epithelium. The results suggest that normally there are some microorganisms present within the periodontal tissues and that their numbers are greater in diseased tissues. However, the data also indicated that significant numbers may be introduced into the tissues during sampling of unfixed tissues.

Detection of HIV-1 RNA in the lamina propria of patients with AIDS and gastrointestinal disease.

Thirty formaldehyde-fixed, paraffin-embedded endoscopic biopsy specimens from the colon and rectum of 25 patients with acquired immunodeficiency syndrome were examined using a [35S]HIV-RNA in situ hybridization procedure. Nine of the specimens contained cells that bound significant amounts of probe. Cells were considered positive if more than 50 grains of silver (over background) per 200 micron 2 were seen over cells that did not stain with eosin. Most of the positive cells resembled macrophages, although cells with condensed nuclei resembling lymphocytes were found. No epithelial cells expressing viral RNA were detected. Formaldehyde-fixed eosinophils gave spurious signals that could be reduced with sulfhydryl modifying agents. HIV-1 may be disseminated in the lamina propria of the gut at low concentrations in some patients but may not be detectable in others. The lower gut lining may be both a portal of initial infection with HIV and a target of disseminated HIV infection.

W2 virus infection of the crustacean Carcinus mediterraneus: a reovirus disease.

Most of the viruses described in marine invertebrates have been related to known virus families only on the basis of ultrastructural properties. Recently a viral agent was isolated and studied in the Mediterranean shore crab Carcinus mediterraneus. This agent, which was 65 to 70 nm in diameter, developed in the cytoplasm of connective tissue cells of C. mediterraneus and produced unusual viral structures, 'rosettes', consisting of an empty sphere bounded by arrangements of viral particles. The capsid consisted of two protein shells. After purification, full virions exhibited a density of 1.34 g/ml in CsCl. The nucleic acid composition of virions was estimated at about 22% and was shown to be a dsRNA with at least nine segments in four different size classes. The capsid contained six polypeptides with Mr of 120 x 10(3), 94 x 10(3), 76 x 10(3), 44 x 10(3), 32 x 10(3) and 24 x 10(3), as determined by SDS-PAGE. From its biological, ultrastructural and physicochemical properties, we propose that this virus should be classified as a new member of the family Reoviridae.

Lack of bacterial invasion in experimental periodontitis.

The present study in the beagle dog was performed to analyze whether micro-organisms from a subgingival microbiota could be translocated into or had the potential to invade the pocket epithelium and the gingival connective tissue during a phase of rapid breakdown of the attachment apparatus. An attempt was also made to assess whether tetracycline therapy suppressed the subgingival microbiota and changed the size and quality of the lesions in the gingival tissue. 5 inbred beagle dogs were used. Throughout the period of experimentation, the animals were fed a soft diet permitting gross accumulation of plaque and calculus. No mechanical plaque control measures were performed during the course of the study. On day 0, a 120-day period of periodontal tissue breakdown was initiated at the right mandibular 3rd and 4th premolars by tying cotton floss ligatures around the neck of these teeth. The process of tissue breakdown at the mandibular left 3rd and 4th premolars was started 30 days later. The ligatures were replaced once every 2 weeks during the subsequent 4-month period. On experimental day 120, the first biopsy was performed and gingival tissue sections prepared for light and electron microscopic assessment of a series of histometric characteristics. On day 120, a 30-day period of tetracycline (per os) administration was initiated. Each dog was given a dose of 500 mg tetracycline twice daily. On day 150, the biopsy procedure was repeated in the mandibular left premolar regions.(ABSTRACT TRUNCATED AT 250 WORDS)