The mucosal attachment at different abutments. An experimental study in dogs

The present experiment was performed to examine if the material used in the abutment part of an implant system influenced the quality of the mucosal barrier that formed following implant installation. 5 beagle dogs were included in the study. The mandibular premolars and the 1st, 2nd and 3rd maxillary premolars were extracted. Three fixtures of the Br?nemark System were installed in each mandibular quadrant (a total of 6 fixtures per animal). Abutment connection was performed after 3 months of healing. In each dog the following types of abutments were used: 2 "control abutments" (c.p. titanium), 2 "ceramic abutments" (highly sintered Al2O3), 1 "gold abutment", and 1 "short titanium abutment". This "short titanium abutment" was provided with an outer structure made of dental porcelain fused to gold. Following abutment connection a plaque control program was initiated and maintained for 6 months. The animals were sacrificed and perfused with a fixative. The mandibles were removed and each implant region was dissected, demineralized in EDTA and embedded in EPON. Semithin sections representing the mesial, distal, buccal and lingual aspects of the peri-implant tissues were produced and subjected to histological examination. The findings from the analysis demonstrated that the material used in the abutment portion of the implant influenced the location and the quality of the attachment that occurred between the periimplant mucosa and the implant. Abutments made of c.p. titanium or ceramic allowed the formation of a mucosal attachment which included one epithelial and one connective tissue portion that were about 2 mm and 1-1.5 mm high, respectively. At sites where abutments made of gold alloy or dental porcelain were used, no proper attachment formed at the abutment level, but the soft tissue margin receded and bone resorption occurred. The abutment fixture junction was hereby occasionally exposed and the mucosal barrier became established to the fixture portion of the implant. It was suggested that the observed differences were the result of varying adhesive properties of the materials studied or by variations in their resistance to corrosion.     

A histological study on tissue responses to titanium implantation in rat maxilla: the process of epithelial regeneration and bone reaction

The present study aimed to establish a titanium implantation model using rat maxillae as well as demonstrate the chronological tissue responses to implantation. Pure titanium implants were inserted in the upper first molar extraction sites of Wistar rats 1 month after tooth extraction. The animals were sacrificed at 1 to 30 days postimplantation, and prepared tissue specimens were processed for light microscopy. The removal of implants from tissue blocks was done using 2 methods: mechanical removal or a cryofracture technique. In the early stages, peri-implant tissues showed severe damage to the oral epithelium and collagen bundles with significant inflammatory cell infiltration. The peri-implant epithelium grew apically along the implant by 10 days postimplantation, and regenerated to show a similar feature of junctional epithelium seen in normal rats at 15 days postimplantation, at which time no signs of inflammation were observed. The regenerated collagen bundles in the connective tissue were arranged circumferentially to the implants in the horizontal sections. New bone formation first appeared around the implants at 5 days postimplantation, covering the entire perimeter of implants by 30 days postimplantation. Scanning electron microscopic observations of the surface texture of the removed implants suggest the probability of an adhesive mechanism between the implants and the peri-implant epithelium and/or the alveolar bone. These findings indicate that this experimental model is useful for detailed analysis of peri-implant tissue because of its easy implantation procedure.     

Maintaining esthetic restorations in the periodontal practice

The aim of present study was to correlate the changes in the peri-implant tissues occurring after functional loading of non-submerged titanium implants and assessed by radiographic, clinical and mobility measurements. 11 patients with distal extension situations received 18 implants of the ITI Dental Implant System. After a healing period of 3 months, the suprastructures were fabricated and seated 5 months post-surgically. For the assessment of peri-implant bone changes, standardized vertical bitewing radiographs with reproducible exposure geometry were evaluated using computer assisted densitometric image analyses (CADIA) and bone height measurements. Since the radiographic evaluations were performed at mesial and distal sites only, the clinical parameters from these implant aspects were included in the analysis. Clinical periodontal parameters modified for the use around implants were obtained, damping characteristics were expressed as Periotest readings and standardized radiographs were obtained at 1, 3, 6, 12 and 24 months after loading. In addition, radiographs were also taken at the start of functional loading. The data obtained from this small sample of implants demonstrated a wide range of different tissue alterations when using radiographic, clinical and mobility assessments. The parameters of probing attachment level (PAL) in combination with radiographic parameters obtained at 1, 3, and 6 months after loading were good predictors for the peri-implant tissue status at 2 years. This was shown by means of multiple stepwise regression analyses. Mobility measurements did not reveal valuable predictive information with the statistical models applied. Assessments of probing attachment levels using periodontal probes rendered information on peri-implant tissue alterations, which were closely correlated to the radiographically measurable peri-implant bone changes.     

The relationship of smoking on peri-implant tissue: a retrospective study

The term "peri-implantitis" is used to describe the formation of deep mucosal pockets around dental implants, inflammation of the peri-implant mucosa, and increased resorption of peri-implant bone. It has been speculated that when left untreated, peri-implantitis can result in implant failure. This retrospective study examines a possible correlation between smoking and the appearance of peri-implantitis. The clinical and radiographic observations of 366 implants in 107 patients who smoke were compared with those of a group of 1000 implants in 314 nonsmoking patients. Despite the retrospective nature of this study, a comparison between the two groups was possible. The mean follow-up period, mean patient age, implant locations, and percentages of fixed partial dentures and overdentures were consistent in both groups. There was no significant difference in the mean maxillary and mandibular hygienic indices between the group of smokers and that of nonsmokers. However, the group of smokers showed a higher score in the bleeding index, the mean peri-implant pocket depth, the degree of peri-implant mucosal inflammation, and radiographically discernible bone resorption mesial and distal to the implant. In the maxilla of the smoking group, these observations were significantly higher than both the mandibular observations for smokers and the maxillary observations of the group of nonsmokers (p < 0.01). No differences between the two groups were observed in the mandible. Aside from the systemic effects of tobacco smoking on the human organism, local cofactors seem to be responsible for the higher incidence of peri-implantitis in smokers and have a particularly negative effect on the maxilla. These findings confirm that smokers treated with dental implants have a greater risk of development of peri-implantitis.     

The relationship between myenteric neuronal denervation, smooth muscle thickening and epithelial cell proliferation in the rat colon

The aim of the present experiment was to (i) study the healing after 3 and 7 months of bone defects filled with cancellous bovine bone mineral and (ii) compare the healing around implants placed in normal bone and in defects filled with bovine bone mineral. 5 beagle dogs, about 1-year-old, were used. At baseline, extractions of all mandibular left and right premolars were performed. Bone defects were prepared in the left mandibular quadrant. The defect was immediately filled with natural bovine cancellous bone mineral particles (Bio-Oss, Geistlich Sons Ltd. Wolhusen, Switzerland). No resective surgery was performed in the right jaw quadrant. In both quadrants the flaps were adjusted to allow full coverage of the edentulous ridge and sutured. 3 months later, 2 dogs (group I) were euthanized and biopsies from the premolar regions obtained and prepared for histologic analysis. The 3 remaining dogs (group II) were at this time interval (3 months) subjected to implant installation in the premolar region of both the right and left mandibular jaw quadrants. 2 fixtures of the ITI Dental Implant System (Straumann, Waldenburg, Switzerland; solid-screw; 8 x 3.3 mm) were installed in each side. The fixtures in the test side were placed within the previously grafted defect area, while the fixtures in the control side were placed in normally healed extraction sites. A 4 month period of plaque control was initiated. At the end of this period, a clinical examination including assessment of plaque and soft tissue inflammation was performed and radiographs obtained from the implant sites. Biopsies were harvested and 4 tissue samples were yielded per dog, each including the implant and the surrounding soft and hard peri-implant tissues. The biopsies were processed for ground sectioning or "fracture technique" and the sections produced were subjected to histological examination. The volume of the hard tissue that was occupied by clearly identified Bio-Oss particles was reduced between the 3- and 7-month intervals. This indicates that with time, Bio-Oss becomes integrated and subsequently replaced by newly formed bone. In other words, this xenograft fulfils the criteria of an osteoconductive material. It was also observed that 4 months after implant installation, the titanium/hard tissue interface at test and control sites exhibited, from both a quantitative and qualitative aspect, a similar degree of "osseointegration".     

The effect of chairside relining materials on rat palatal mucosa

OBJECTIVES: To investigate the effects of denture relining materials on oral mucosa in vivo in a rat model. METHODS: Denture-like appliances covering the palate in Wistar rats were relined with a resilient soft linting material and a hard 'chairside' relining material. The effects on the palatal epithelium were studied by quantitative analysis using computerized planimetry. RESULTS: The relining materials caused an increase in the thickness of the keratinized layer, while not increasing the total epithelial thickness. CONCLUSIONS: Relining materials are not totally without effect on oral mucosa. Further in vivo research is indicated.     

The Orthosystem--a new implant system for orthodontic anchorage in the palate

The present report describes the design and first clinical experiences of a newly developed endosseous orthodontic implant anchor system (Orthosystem, Institut Straumann, Waldenburg, Switzerland) for palatal anchorage. The 1-piece fixture made of titanium consists of a screw-type endosseous implant body (sandblasted, acid-etched, diameter 3.3 mm, lengths: 4 and 6 mm), a cylindrical polished transmucosal neck and an abutment. Clamp-caps provide attachment of square commercially available orthodontic wires (0.032 x 0.032 inch, SS) to the abutment (transpalatal bars). In a pilot study 1 fixture (implant body length: 6 mm) was inserted into the midsagittal anterior palatal region in each of 6 adult patients with Angle class II malocclusion (distocclusion 7 to 8 mm, overjet: approximately 9 mm). The treatment plan included extraction of the first maxillary premolars and retraction of the anterior teeth based on maximum anchorage of the posterior teeth without using compliance-dependent anchorage aids (headgear, class II elastics). Due to the design of the fixture only 1 simple surgical procedure was required for insertion (nonsubmerged method, 1-stage surgery). Accordingly the need for surgical exposure of the abutment for connection and wire insertion was eliminated. Thus, inconvenience to patients was reduced to a minimum. The patients are now at varying active treatment stages. The course of treatment of the most advanced case is described. Evaluation of the clinical and radiological findings after 12 months of treatment (3 months implant healing, 9 months active orthodontic treatment which is equal to the implant loading period) revealed no implant mobility/dislocation, favourable peri-implant soft tissue conditions, no marked mesial movement (approximately 0.5 mm) of the implant/transpalatal bar supported posterior teeth, and 8 mm retraction of the anterior teeth. Retrieval of the fixture and post-operative wound healing were uncomplicated. In the treatment of this case, no compliance-dependent extraoral anchorage was used, and the well aligned mandibular dentition was not bonded provide anchorage support (class II elastics).     

Tooth mobility and resolution of experimental periodontitis. An experimental study in the dog

The aim of the present experiment was to study alterations in the mobility of teeth that occurred during resolution of experimentally induced periodontitis lesions in the dog. 5, 1-year-old, beagle dogs were used in the study. The left and right 4th, 3rd, and 2nd mandibular premolars (4P4, 3P3, 2P2) served as experimental teeth. Periodontal tissue breakdown was initiated by placing plaque-collecting cotton-floss ligatures around the neck of the experimental teeth. The ligatures were replaced to the level of the receding gingival margin 1 x every month. On Day 120, the ligatures were removed and debridement was performed. A groove, parallel to the long axis of the mesial root, was prepared in the mesio-buccal surface of the crowns of 2P and P2. Guided by the groove and with a probing force of 0.5 N, a probe was inserted into the buccal gingival pocket of the mesial root and was attached to the buccal surface. Biopsies including both the mesial and distal root of 2P and P2 and the surrounding hard and soft tissues were harvested. The biopsy procedure was repeated in a similar manner 15 days (i.e. Day 135) and 3 months (i.e. Day 225) after ligature removal in the 4th (4P4) and 3rd (3P3) premolar regions. After fixation, decalcification and sectioning, the biopsy material was exposed to histometric and morphometric measurements. Assessment of the mobility of the experimental teeth was performed on Days 120, 135 and 225 using the Periotest system.(ABSTRACT TRUNCATED AT 250 WORDS)     

Delayed implants in the anterior maxilla with the IMZ-implant system: a radiographical evaluation

One hundred and seventy-three IMZ-implants in 81 patients, placed in the anterior region of the maxilla, were evaluated radiographically by two observers. Radiographs were evaluated at three intervals, namely at the time of implant placement, the time of prosthetic restoration and at the latest available radiograph, on average 2 1/2 years after implant placement. In this study marginal bone height and the type of radiolucency adjacent to the implant were determined. Both observers were able to classify the marginal bone height (mesial and distal) and the distinctive type of resorptive defects to an acceptable level of agreement, with Cohen's kappa ranging between 0.48 and 0.69. It was found that, at the most recent visit to the clinic, angular-shaped resorptive defects are found mesially and/or distally of the implants at approximately 25% of the implants. At this stage 20.7% of the mesial implant sites and 27.9% of the distal implant sites show marginal bone heights less than three-quarters of the implant length. These findings do not fully underscore and sometimes even contradict the clinical observations which were considered highly satisfactory.     

Studies on prevalence of Strongyloides infection in Holambra and Maceió, Brazil, by the agar plate faecal culture method

OBJECTIVE: To test the hypothesis that the anti-apoptotic ability of Epstein-Barr virus (EBV) may result in altered expression of apoptosis-associated proteins in oral hairy leukoplakia (HL), we evaluated HL tissue and normal epithelium for these proteins by immunohistochemistry. MATERIALS AND METHODS: Twenty formalin-fixed, paraffin-embedded specimens of HL lesions and six specimens of normal control mucosa were selected from archived tissue specimens. Bcl-2, Bcl-x, Bax and p53 apoptosis-associated proteins were evaluated in immunohistochemically stained tissue sections according to staining intensity and pattern. The percentage of p53-positive basal cells was estimated in sequential fields. RESULTS: Generally, there were only slight differences in the expression of Bcl-2 and Bcl-x proteins in the epithelium of HL and control tissue. The staining for Bcl-2 was weaker in keratinocytes than in putative melanocytes and Langerhans cells. Equivocal diffuse cytoplasmic staining of prickle cells was also noted. Keratinocytes throughout the epithelium stained positively for Bcl-x protein, although upper layers were more weakly stained. The 'balloon' keratinocytes in HL were infrequently positive for Bcl-x. Bax staining in HL differed from that in control tissue in being more heterogeneous. The staining reaction in HL was weak to negative in upper epithelial levels where 'balloon' keratinocytes were located. Weak to moderate nuclear p53 protein staining was detected in a mean of 25.3% of basal keratinocytes in all but one of the HL specimens; weak staining was seen in only two control specimens. CONCLUSIONS: We found only slight immunohistochemical evidence that expression of the apoptosis-associated proteins is altered in HL. p53 appears to over-expressed in HL; we speculate that this may be related to up-regulation or stabilization of wild-type p53 protein related to EBV infection.     

Health human periodontal versus peri-implant gingival tissues: an immunohistochemical differentiation of the extracellular matrix

Healthy human periodontal and peri-implant (ITI Bonefit) keratinized gingival tissues were studied immunohistochemically to evaluate the possible presence of structural differences in the extracellular matrix protein localization. Collagen types I, III, IV, and VII and fibronectin showed similar distribution in these tissues. Compared to the periodontal tissues, collagen type V was localized in higher amounts in the lamina propria of the peri-implant gingival tissues. Collagen type VI stained the periodontal tissues as a delicate microfibrillar network contrasting to the not well-stained peri-implant gingival tissues. The data show that structural differences between these tissues are present. The structural differences may be responsible for the defense of peri-implant keratinized gingival connective tissues to bacterial penetration, because of the high amount of the collagen type V component, which is responsible for the higher collagenase stability.     

Urethroplasty of the free colonic mucosa in rats. Preliminary study of the use of appendicular mucosa

The various tissues used as free grafts in urethroplasties are associated with a high incidence of fistulae and strictures. The search for a new, more effective substitute had led the authors to study the possibility of using a new type of mucosa: appendicular mucosa. The size and cylindrical structure of the appendix and its easy resection make it an original and adapted urethral substitute. As most animals do not possess an appendix, an animal model of urethroplasty with colic mucosa has been used. A segmental distal urethrectomy has been performed on 40 rats, 14 had a simple urethral stent without any urethroplasty (Group I), for 7 wi performed the urethroplasty with a collagen tube (Group II) and for 19 an urethroplasty with free colic mucosa was performed (Group III), 3 to 6 weeks later, a macroscopic and microscopic study were realised. In group I and II the urethral duct developed a fibrosis and all rats had a severe stenosis when the stent went out. In those two groups, a urinary fistula has been developed in all rats except one. In group III, a neo-urethra was found. Under light microscopic examination a typical urothelium was observed in the mid and distal section and a keratinized squamous epithelium on the distal section. The results of the preliminary study let us believe that the digestive mucosa may be used for urethroplasty. Before we can propose the appendix mucosa in human surgery, it will be useful to perform sooner histological examination, then the genesis of the neo-urothelium should be understood.     

Effect of chemotherapy for acute myelogenous leukemia on hematopoietic and fibroblast marrow progenitors

AIMS: The generation and characterisation of a monoclonal antibody that specifically recognises the mdr-1 encoded protein, P-glycoprotein (P-170), on routinely processed formalin fixed, paraffin wax embedded tissue sections. METHODS: The monoclonal antibody, designated 6/1C, was produced following a combination of in vivo and in vitro immunisation regimens in Balb/c mice with a synthetic 12 amino acid peptide that corresponds to amino acids 21-32 (believed to be intracellularly located) of P-170 and has insignificant homology with the mdr-3 encoded P-170. Antibody 6/1C was characterised by western blotting and immunocytochemistry on cytospins of paired multidrug resistant or sensitive cell lines, including mdr-1 and mdr-3 transfected cells, and by immunohistochemistry on normal and malignant formalin fixed paraffin wax embedded tissue sections. RESULTS: Antibody 6/1C showed a single band at 170 kDa on western blots of multidrug resistant cell lysates and mdr-1 transfected cell lysates that was absent on similar preparations of drug sensitive cells and mdr-3 transfected cells. Immunocytochemical studies on cytospins of multidrug resistant cells and mdr-1 transfected cells revealed strong inner plasma membrane/cytoplasmic staining. Staining was negligible on drug sensitive cells and cells transfected with the mdr-3 gene. Immunohistochemical studies on formalin fixed, paraffin wax embedded normal adult kidney, liver, and breast tissue and a range of fetal tissues exhibited staining patterns of a variety of secretory surfaces consistent with documented mdr-1 specific staining. Specific staining of malignant cells in similarly treated sections of breast tumours was seen also with antibody 6/1C. Staining on paraffin wax embedded tissue with this antibody did not require any pretreatment of tissue sections. CONCLUSIONS: This new monoclonal antibody, chosen for its specificity with the mdr-1 encoded P-170 and its reactivity on routinely fixed paraffin wax embedded tissue samples without pretreatment, appears to be useful for the investigation of P-170 in archival material. It is especially useful for retrospective studies on pretreatment and post-treatment tissue sections, and could help establish when and how rapidly mdr-1 associated drug resistance develops during chemotherapeutic regimens. Immunohistochemical assessment of P-170 expression in many cancers has potential for diagnostic purposes and may influence the choice of chemotherapeutic drugs used in the treatment of refractory tumours.     

Evidence for stimulus access to taste cells and nerves during development: an electron microscopic study

We have examined developing taste buds in fungiform papillae of rats from the 18th day of gestation (E18) to the 15th postnatal day (P15). Nerve processes were seen in the epithelium of E18 rats before taste buds were obvious. At E20, early taste buds were visible, but were embedded within the epithelium, i.e., their cells were shielded from the oral cavity by overlying squamous epithelium. At this stage, the epithelium on the lateral aspects of the fungiform papillae was keratinized, but that overlying the taste bud was not. Some taste bud cells at E20 contained synapse-like structures near their contacts with nerve processes. In postnatal animals, keratinized epithelial cells were seen overlying taste buds, but taste pores were not observed until P10. How, then, do stimuli reach the taste cells and elicit physiological and behavioral responses as reported by others? The keratinized epithelium overlying the buds was unlike that on the lateral aspect of the papilla in at least one significant way. Few lamellated bodies were present in intercellular spaces beneath the stratum corneum, whereas these were abundant in the corresponding location within epithelium on the slope of the papilla. Although some were present within the squamous epithelium overlying the bud, they apparently were not released into the intercellular space. These lipid-rich lamellated bodies are thought to represent the water barrier of the epithelium, i.e., the barrier which prevents aqueous solutions from passing through the epithelium. We determined that the keratinized epithelium overlying the taste bud was permeable to a tracer, lanthanum nitrate, whereas that on the lateral surface was not. Lanthanum was visualized around taste cells and around nerve profiles within and near the taste bud. We propose that the absence of an aqueous permeability barrier in the epithelium overlying taste buds likely explains the ability of tastants to reach the taste bud cells and nerves in the developmental period before pore formation.     

Collagenase-3 (matrix metalloproteinase-13) expression is induced in oral mucosal epithelium during chronic inflammation

Increased proliferation of mucosal epithelium during inflammation is associated with degradation of subepithelial connective tissue matrix and local invasion of the epithelial cells. Here we have studied, whether collagenase-3 (MMP-13), a collagenolytic matrix metalloproteinase with an exceptionally wide substrate specificity, is expressed in the epithelium of chronically inflamed mucosa. Examination of human gingival tissue sections from subjects with chronic adult periodontitis with in situ hybridization revealed marked expression of MMP-13 in basal cells of some epithelial rete ridges expanding into connective tissue. Immunohistochemical staining demonstrated that these cells also expressed strongly laminin-5, suggesting that they are actively migrating cells. A strong signal for MMP-13 mRNA was occasionally also noted in the suprabasal epithelial cells facing the gingival pocket, whereas no collagenase-1 (MMP-1) mRNA was detected in any areas of the epithelium. MMP-13 expression was also detected in fibroblast-like cells associated with collagen fibers of the inflamed subepithelial connective tissue. In organ culture of human oral mucosa, MMP-13 mRNA expression was observed in epithelial cells growing into connective tissue of the specimens. Regulation of MMP-13 expression was examined in cultured normal nonkeratinizing epithelial cells isolated from porcine periodontal ligament. In these cells, MMP-13 expression at the mRNA and protein level was potently enhanced (up to sixfold) by tumor necrosis factor-alpha, transforming growth factor-beta(1), and transforming growth factor-alpha and by keratinocyte growth factor in the presence of heparin. In addition, plating periodontal ligament epithelial cells on type I collagen stimulated MMP-13 expression (sevenfold) as compared with cells grown on tissue culture plastic. The results of this study show, that expression of MMP-13 is specifically induced in undifferentiated epithelial cells during chronic inflammation due to exposure to cytokines and collagen. Thus, it is likely that MMP-13 expression is instrumental in the subepithelial collagenolysis and local invasion of the activated mucosal epithelium into the connective tissue.     

Carcinosarcoma and pseudosarcoma of the esophagus: two names, one disease--comprehensive review of the literature

The purpose of this investigation was to evaluate the treatment effects of an intraoral appliance used for rapid distal movement of the maxillary molars. The appliance studied, the Jones jig, is designed to deliver a distalizing force to the maxillary molar against an intraoral anchorage unit thereby eliminating the need for patient compliance. A retrospective study was performed comparing before and after lateral cephalometric radiographs on 13 patients who were treated for an average of 26 weeks with the Jones jig. The cephalometric radiographs were evaluated to determine if there were significant differences between pretreatment and posttreatment variables that included skeletal, dental and soft tissue relationships. Differences between the pretreatment and posttreatment means were significant for mesial angulation of the premolar anchorage unit (P <.001), distal movement of the maxillary molars (P <.01), mesial movement of the premolar anchorage unit (P <. 01), mesial movement of the maxillary incisors (P <.001), and increased lower anterior facial height (P <.01). The anchorage loss, flared maxillary incisors, and increased facial height are negative treatment effects that should be expected when using this or similar appliance design.     

The epidemiology, clinical characteristics, and natural history of older nursing home residents with a diagnosis of Parkinson''s disease

This study investigated the occlusal stress distribution to the implant and soft tissue for the implant-retained overdenture. The stress at the molar residual ridge and the strain around the implant were measured on an experimental resin cast using static and dynamic loading. The influence of connecting structures of stud attachments on stress distribution was discussed. The occlusal stress had a tendency to concentrate on the implant, especially in the areas distal to the implant. The modified magnetic attachment system, using a silicone-covered magnet, provided the optimal stress distribution.     

Bicuculline administered into the amygdala after training blocks benzodiazepine-induced amnesia

Leukocytes in the forestomach mucosa of reindeer (Rangifer tarandus tarandus L.) were investigated by immunoperoxidase staining of cryostat sections, using monoclonal antibodies against antigens on sheep leukocytes. Mucosal samples from three free-ranging reindeer calves were compared with samples from three calves fed baled grass silage previously shown to induce increased frequency of lesions in the ruminal epithelium. In both groups, MHC-II + cells and gamma delta T cells were observed, located within or just below the basal layer of the stratified epithelium. Computer-assisted morphometric analysis showed that the number of gamma delta T cells in the ruminal mucosa was higher in the silage-fed than in the free-ranging animals. No marked difference in number of MHC-II + Langerhans cells was observed between the groups.     

The regenerative potential of oxytalan fibers. An experimental study in the monkey

Although a number of studies have described the oxytalan fibers as being a natural component of the periodontal ligament, little information exists about the regenerative potential of these connective tissue fibers. The aim of the present study was to examine whether oxytalan fibers have the capacity to reform after regenerative periodontal therapy. Intrabony defects were produced surgically at the mesial aspects of teeth 37, 35, 45, 47 and at the distal aspects of teeth 11, 21, 31, 41 in one monkey (Macaca fascicularis). After 3 months, the defects were exposed using a full-thickness flap procedure. The root surfaces were debrided and subsequently PDGF-growth factors were placed in the defects. 4 of the 8 sites were covered with a bioresorbable membrane before closure of the wound. Post-surgically, antibiotics were given systemically for 1 week, and tooth cleaning was carried out 1x a week during the entire experimental period. After 5 months, the animal was sacrificed and the oral tissues were fixed by perfusion with 10% buffered formalin. Specimens containing the defects and surrounding tissues were dissected free and histological sections were cut in the mesio-distal direction, parallel to the long axes of the teeth. The sections were stained with hematoxylin and eosin or with the oxone-aldehyde-fuchsin-Halmi staining method and subsequently examined in the light and in the electron microscope. The results revealed that new oxytalan fibers oriented mainly in an apico-occlusal direction had developed in the regenerated periodontal ligament. Many of the newly-formed fibers were inserted into the new cementum, thus suggesting a strong relationship between this tissue and the oxytalan fibers. It is concluded that the regenerated periodontal ligament connective tissue formed after surgery contains oxytalan fibers similar to those present in the original tissue. These results demonstrate that oxytalan fibers develop de novo in the newly-formed periodontal ligament.     

A comparison of fluticasone propionate, 1 mg daily, with beclomethasone dipropionate, 2 mg daily, in the treatment of severe asthma. International Study Group

Cytochrome P450 1A1 was localized immunohistochemically and benzo[a]pyrene hydroxylase activity was identified in situ by means of fluorescence histochemistry in the nasal mucosa of untreated, 3-methylcholanthrene-treated or Aroclor 1254-treated rats. Cytochrome P450 1A1 was localized predominantly within Bowman's glands, with considerably less staining occurring in the olfactory epithelium of untreated rats. Similarly, benzo[a]pyrene was hydroxylated to the greatest extent in Bowman's glands and, to a lesser extent, in olfactory epithelial cells. Pre-treatment of tissue sections of nasal mucosa with anti-P450 1A1 inhibited most of the benzo[a]pyrene hydroxylase activity present. Although 3-methylcholanthrene treatment did not affect either cytochrome P450 1A1 or hydroxylase activity in the nasal mucosa, a single intraperitoneal injection of Aroclor 1254 significantly increased anti-P450 1A1 binding in Bowman's glands and in the olfactory and respiratory epithelia, and dramatically enhanced benzo[a]pyrene hydroxylase activity in the epithelia and the subepithelial ducts and glands in both the olfactory and respiratory regions. In contrast to its effects on cytochrome P450 1A1, Aroclor 1254 produced a considerably greater induction of hydroxylase activity in the respiratory region, especially in the seromucous glands, than in the olfactory region. These results suggest that Aroclor 1254 treatment also induces other forms of cytochrome P450 in the respiratory region of the nasal mucosa.