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Results for “ALVEOLAR PROCESS”

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At least 1,261 records · Page 70Linked to original sources
PubMed1999

Perflubron enhances adenovirus-mediated gene expression in lungs of transgenic mice with chronic alveolar filling.

Perfluorochemical (PFC) liquids have both low surface tension and a high capacity to dissolve O2 and CO2, and have been shown to improve gas exchange and lung compliance in animal models of lung injury. We have previously demonstrated that perflubron and other PFC liquids enhance transgene expression in lungs of spontaneously breathing normal rodents after intratracheal instillation of either adenoviral or liposomal vectors followed by a single instillation of PFC liquid. We reasoned that PFC liquids may also be useful for enhancing transgene expression in abnormal lungs. GM-CSF knockout mice develop chronic accumulation of surfactant lipids and proteinaceous material in alveolar spaces and serve as a useful model of chronic alveolar filling. Intratracheal instillation of the adenoviral vector Adlac-Z resulted in patchy in situ distribution of beta-Gal activity, predominantly in larger proximal airways. In contrast, in mice instilled with Adlac-Z followed by instillation of a single dose of perflubron (10 ml/kg body weight), increased expression was observed in distal airway and alveolar epithelial cells. In particular, expression was observed in epithelial cells of debris-filled alveoli. Spectrophotometric measure of quantitative beta-Gal activity in lung homogenates demonstrated increased activity in lungs of mice receiving Adlac-Z plus perflubron compared with lungs of animals receiving Adlac-Z alone. These studies demonstrate that use of perflubron enhances transgene expression in lungs of animals with a chronic alveolar filling process. This approach may be applicable for gene delivery in diseases marked by chronic airway or alveolar filling such as cystic fibrosis.

Adenoviridae↗
PubMed1999

Neural modulation of inflammatory reactions in dental tissues incident to orthodontic tooth movement. A review of the literature.

This article reviews the current knowledge of the biological aspects of dental tissue changes incident to orthodontic tooth movement. The inflammatory nature of these tissue changes was first recognized in the early 1970s, and since then a number of morphological and quantitative investigations have been published in support of this view. The studies dealing with vascular and cellular dental tissue changes, as well as those concerned with inflammatory mediators present at sites of orthodontic tooth movement are systematized and presented accordingly. Special emphasis is placed upon the role of the sensory nerve fibres and their neuropeptides in the control, and development of an inflammatory process, i.e. their role in tooth movement.

Alveolar Process↗
PubMed2002

Morphofunctional and clinical study on mandibular alveolar distraction osteogenesis.

Alveolar Distraction Osteogenesis (ADO) is a process which forms new alveolar bone to correct alveolar deformities in ridge height and width. This work aims (a). to verify the predictability of the augmentation of height of atrophic alveolar ridges using an extra-alveolar distraction device and (b). to study the bone processes in order to optimize implanto-prosthetic rehabilitation. ADO was performed on 10 patients with ridge deformities to obtain the required ridge augmentation. Clinical and radiological (OPT and CT with densitometric assay) evaluations were carried out during the following 12 weeks, before implant insertion. Biopsies at 40, 60 and 88 days were studied after general, specific and histochemical staining of slides; microradiographs were analyzed to evaluate the Trabecular Bone Volume. Forty days after the end of distraction, soft callus indicated the start of ossification. Sixty days after the end of distraction, the soft callus was largely converted into a network of trabecular woven bone; osteogenic activity was high and TBV was about 50%. Eighty-eight days after the end of distraction, the amount of bone appeared reduced, with a more ordered structure; bone formation activity and TBV also diminished, whereas osteoclast erosion was active. The densitometric assay shows values increasing from the end of distraction, particularly after implant insertion. Histological results show a regression in bone deposition processes 88 days after the end of distraction culminating in a virtual steady-state after a certain time. The results suggest that early implant insertion may be desirable to avoid bone loss due to mechanical unloading.

Absorptiometry, Photon↗
PubMed2003

[Topography of the inferior alveolar nerve in relation to cystic processes of the mandible in dental MRI].

PURPOSE: Cystic processes are changing the course of the inferior alveolar nerve in the mandible. This study evaluates the possibility of demonstrating the relationship between space-occupying processes and the course of the neurovascular bundle. MATERIALS AND METHODS: Thirteen patients with cystic processes in the mandible (9 keratocystic lesions, 1 eosinophilic granuloma, 1 plasmocytoma, 2 adamantinomas) were examined by MRI (1.5-T magnet, 8-cm surface coil, PD-gradient-echo-sequences in sagittal and coronal orientation, without enhancement) and the results retrospectively evaluated. RESULTS: The entire course of the nerve could be delineated in all patients. In six patients with minor cystic processes, the nerve was identified in both sagittal and coronal orientation. In seven patients with major cystic lesions, only parts of the nerve were detected in either image orientation, but the nerve could be visualized in its entire length by evaluating coronal and sagittal images side by side. CONCLUSION: It is possible to delineate the inferior alveolar nerve in its entirety along pathologic mandibular lesions. For large cystic lesions, this requires the evaluation of both coronal and sagittal sections of multidirectional MRI.

Adolescent↗
PubMed2003

Gene expression of growth differentiation factors in the developing periodontium of rat molars.

Growth and differentiation factors (GDF) 5, 6, and 7 are known to play roles in tendon and ligament formation, and are therefore probably involved in the formation of periodontal ligament. In this study, we sought to determine temporal and spatial expression of GDF-5, -6, and -7 mRNA in developing periodontal tissue of rat molars using in situ hybridization. GDF gene expression in the periodontal ligament was first detected in cells associated with the initial process of periodontal ligament fiber bundle formation. Gene signals were also detected in cells located along the alveolar bone and cementum surfaces, the insertion sites of periodontal ligaments, during the course of root formation. GDF expression in these cells were down-regulated after completion of root formation. Our results appeared to suggest the involvement of GDF-5, -6, and -7 in the formation of the dental attachment apparatus.

Alveolar Process↗
PubMed1985

Orthodontic extrusion of single-rooted teeth affected with advanced periodontal disease.

Orthodontic extrusion of teeth with advanced periodontal disease was evaluated in beagle dogs. Surgical destruction of one third to one half of the attachment apparatus and the inducement of chronic periodontal disease was accomplished on the hemisected mesial roots of the mandibular premolars. The roots on one side of the mandible were extruded toward a cemented stainless steel bridge by means of elastics providing 20 to 25 gm of force. The force was examined daily. When extruded teeth came into contact with the bridge, they were ligated in place for 21 days of stabilization. Clinical results showed that control teeth maintained their position and signs of advanced periodontitis. Extruded teeth had shallower pocket depths, less gingival inflammation, and no bleeding on probing. Radiographic evaluation showed no demonstrable changes in the control teeth. Early in the extrusion process, the teeth appeared to be avulsed, with more than three fourths of the root coronal to the alveolar crest. After stabilization, approximately 2 mm of new bone was seen coronal to the original alveolar crest, and the periapical areas had filled in as well. This bone formation was verified histologically. The extruded teeth had an intact attachment apparatus with all components in the same relative position on the teeth as in the controls. However, a shallower sulcus and less gingival inflammation were noted in the extruded teeth. There were statistically significant findings of a wider periodontal ligament space, greater cementum width, and increased bone height in the crestal areas of extruded teeth. Extruded teeth also had less cementum width and greater new bone formation at the apex.(ABSTRACT TRUNCATED AT 250 WORDS)

Alveolar Process↗
PubMed1994

Effects of smoke inhalation on alveolar surfactant subtypes in mice.

The effects of smoke inhalation on alveolar surfactant subtypes were examined in mice exposed for 30 minutes to smoke generated from the burning of a flexible polyurethane foam. At 4 or 12 hours after the exposure, three surfactant pellets, P10, P60, and P100, and a supernatant, S100, were prepared by sequential centrifugation of lavage fluids at 10,000 g for 30 minutes (P10), 60,000 g for 60 minutes (P60), and 100,000 g for 15 hours (P100 and S100). Phospholipid analysis and electron microscopy were performed on each fraction. Smoke exposure dramatically altered the normal distributions of these fractions: it significantly increased the phospholipid content of the heavier subtype, P10, which is thought to represent newly secreted surfactant; had no effect on the intermediate form, P60; and dramatically increased the phospholipid content (approximately fivefold) of the lighter subtypes, P100 and S100, which are believed to represent catabolic end-products of alveolar surfactant. Only P100 was structurally altered by the smoke. These results represent alterations of the normal metabolic processing of alveolar surfactant. Whereas the mechanism is yet to be defined, it seems to involve a small but significant increase in the newly secreted surfactant, as well as an excessively high accumulation of the structurally altered catabolic forms of the secreted surfactant.

Animals↗
PubMed2001

A comparison between friction and frictionless mechanics with a new typodont simulation system.

This study was designed to explore the differences between friction and frictionless mechanics for maxillary canine retraction with the use of a new typodont simulation system, the Calorific machine system. The unit was designed to observe the whole process of tooth movement and is composed of 3 parts: a temperature regulating system, electrothermodynamic teeth, and an artificial alveolar bone component. The efficiency of maxillary canine retraction was compared with the sliding mechanics (along a.016 x.022-in stainless steel labial arch and nickel-titanium closed coil spring) and a canine retraction spring. The patterns of tooth movement obtained with both of these mechanics were measured 5 times each. Friction mechanics were superior to frictionless mechanics in terms of rotational control and dimensional maintenance of the arch (P <.0001); frictionless mechanics were shown to be more effective at reducing tipping and extrusion (P <.0001). However, the observed differences between the 2 methods were relatively small in terms of their clinical significance, and no differences were found in anchorage control (P =.2078). In conclusion, this study indicated that friction and frictionless mechanics perform similarly.

Alveolar Process↗
PubMed1992

Short term bone healing in calcium deficiency osteopenia and disuse osteopenia: experimental studies in adult rats.

Adult male Sprague-Dawley rats (average weight 530-540 g) were studied in two different series. In series I, studying disuse osteopenia, the experimental rats had all maxillary molars extracted on one side. After 16 wk they had their mandibular first molar of the corresponding side extracted and were followed for another 4 wk. In series II, studying calcium deficiency osteopenia, the experimental rats were given a low calcium diet for 16 wk and at this time had their mandibular first molars extracted. Both disuse and calcium deficiency caused osteopenia, which did not seem to impair the healing process after tooth extraction in the short term. One puzzling finding in the disuse series (I) was that the alveolar height at the extraction site was higher in the experimental than in the control group 4 wk after extraction.

Alveolar Process↗