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Biomedical subjects

U Skaleric

Publications and source records attributed to U Skaleric.

At least 19 recordsLinked to original sources
PubMed2002

Comparative evaluation of JPEG and JPEG2000 compression in quantitative digital subtraction radiography.

OBJECTIVES: The aim of this in vitro study was to compare the impact of JPEG and the novel JPEG2000 compression standard on quantitative digital subtraction radiography (DSR) and to determine the acceptable JPEG2000 compression ratios for DSR. METHODS: Nine dry pig mandible sections were radiographed three times ('Baseline', 'No change', and 'Gain') with standardized projection geometry. Bone gain was simulated by adding artificial bone chips (1, 4 and 15 mg). Images were registered, compressed by JPEG and JPEG2000 using compression ratios (CR) of 1 : 7, 1 : 16, 1 : 22, and 1 : 31, and then subtracted. Image distortion was assessed objectively by calculating average pixel error and peak signal to noise ratio. No change areas in compressed and subtracted 'No change-Baseline' images and bone gain volumes in compressed and subtracted 'Gain-Baseline' images were calculated for both compression standards and compared. RESULTS: JPEG introduced less distortion at low CRs, while JPEG2000 was superior at higher CRs. At CR of 1 : 7, no significant difference between JPEG and JPEG2000 was found. JPEG2000 yielded better results for no change measurements at higher CRs. Volumes of simulated bone gain were overestimated when JPEG and underestimated when JPEG2000 compression was used. CONCLUSIONS: At CR of 1 : 7 JPEG and JPEG2000 performed similarly, which indicates that CR of 1:7 in JPEG2000 can be used for DSR if images are registered before compression. At higher CRs, JPEG2000 is superior to JPEG but image distortions are too high for reliable quantitative DSR.

Algorithms↗
PubMed2002

Impact of JPEG lossy image compression on quantitative digital subtraction radiography.

OBJECTIVES: The aim of the study was to evaluate the impact of JPEG lossy image compression on the estimation of alveolar bone gain by quantitative digital subtraction radiography (DSR). METHODS: Nine dry domestic pig mandible posterior segments were radiographed three times ('Baseline', 'No change', and 'Gain') with standardized projection geometry. Bone gain was simulated by adding artificial bone chips (1, 4, and 15 mg). Images were either compressed before or after registration. No change areas in compressed and subtracted 'No change-Baseline' images and bone gain volumes in compressed and subtracted 'Gain-Baseline' images were calculated and compared to the corresponding measurements performed on original subtracted images. RESULTS: Measurements of no change areas ('No change-Baseline') were only slightly affected by compressions down to JPEG 50 (J50) applied either before or after registration. Simulated gain of alveolar bone ('Gain-Baseline') was underestimated when compression before registration was performed. The underestimation was bigger when small bone chips of 1 mg were measured and when higher compression rates were used. Bone chips of 4 and 15 mg were only slightly underestimated when using J90, J70, and J50 compressions before registration. CONCLUSIONS: Lossy JPEG compression does not affect the measurements of no change areas by DSR. Images undergoing subtraction should be registered before compression and if so, J90 compression with a compression ratio of 1:7 can be used to detect and measure 4 mg and larger bone gain.

Alveolar Process↗
PubMed2002

Immunolocalization of inducible nitric oxide synthase in localized juvenile periodontitis patients.

Localized juvenile periodontitis (LJP) is associated with a destruction of periodontal tissues and the presence of Actinobacillus actinomycetemcomitans (AA). Lipopolysaccharide (LPS) from AA was found to induce a significant macrophage production of nitric oxide (NO). Increased nitric oxide synthase (NOS) activity was found to be negatively correlated with the neutrophil chemotactic response. The aim of this study was to determine the occurrence and distribution of inducible NOS (iNOS) in human gingival tissue from LJP patients. The distribution of iNOS was assessed by monoclonal antibody against iNOS. Cellular markers (CD 3, CD 20, and CD 68) were used to determine the cellular origin of iNOS. The immunostaining revealed the appearance of iNOS in inflamed compared to noninflamed gingival tissues. Macrophages expressed high levels of iNOS that may cause some damage to the periodontal tissues. This study suggests that iNOS activity in macrophages may modify abnormalities of neutrophil function.

Adolescent↗
PubMed2001

Morphology, chemical structure and diffusion processes of root surface after Er:YAG and Nd:YAG laser irradiation.

OBJECTIVES: The aim of this in vitro study was to evaluate the effects of Er:YAG and Nd:YAG lasers on morphology, chemical structure and diffusion processes of the root surface. MATERIAL AND METHODS: 60 root samples were irradiated for 1 min each either with 60 mJ/p, 80 mJ/p and 100 mJ/p using Er:YAG laser or with 0.5W, 1.0W and 1.5W using Nd:YAG laser. Scanning electron microscopy (SEM) was used to determine the morphology, infrared (IR) spectroscopy to assess the alterations in chemical structure and one dimensional electron paramagnetic resonance imaging (1-D EPRI) was used to estimate the diffusion coefficients in dental root samples. RESULTS: Er:YAG laser treatment resulted in deep crater formation with exposed dentin. Morphological alterations of root surface after Nd:YAG laser irradiation included cracks, crater formation, meltdown of the root mineral and resolidified porous globules formation. Er:YAG laser failed to alter the intensity of Amide peaks I, II or III. In contrast, treatment with Nd:YAG laser, using the highest power setting of 1.5W, reduced the intensity of Amide peak II and III in comparison to the control. The diffusion coefficients were increased significantly in all Er:YAG and Nd:YAG treated root samples. CONCLUSION: This study demonstrated that Er:YAG laser influences only on morphology and diffusion processes of root surfaces, while Nd:YAG laser also alters the chemical structure of root proteins.

Aluminum Silicates↗
PubMed2001

Detection of hepatitis C virus RNA from gingival crevicular fluid and its relation to virus presence in saliva.

BACKGROUND: To search for a possible source of hepatitis C virus (HCV) in saliva, the presence and shedding patterns of HCV in gingival crevicular fluid (GCF) and saliva of HCV viremic patients were assessed based on clinical, biochemical, histological, virological, and oral health parameters. METHODS: Saliva and GCF samples of 50 HCV viremic patients were collected to detect HCV RNA by a modified commercial polymerase chain reaction (PCR) assay. Clinical oral examination was performed and periodontal status at the collection sites was monitored. The results were correlated to specified parameters. RESULTS: HCV RNA was detected in 59% (29/49) of the GCF specimens and in 35% (17/48) of the saliva specimens. In saliva specimens, HCV RNA was detected only in cases which also had detectable HCV RNA in the GCF samples (P=0.00002) and was significantly related to the presence of blood in saliva (P=0.03). Higher, but not significant, values of oral clinical parameters at the sites of fluid collection were found in GCF specimens harboring HCV RNA. In GCF specimens with no blood detected, HCV RNA was more often present in cases with higher plasma viral load (P=0.05). CONCLUSIONS: The results suggest that besides blood, the other most probable source of HCV in saliva is GCF. Unknown endogenous HCV inhibitory mechanisms in the oral cavity may explain the discrepancies in HCV appearance between saliva and GCF. The results provide a biologic basis for further investigation of the role of HCV in the pathogenesis of periodontal disease.

Adult↗
PubMed2000

Local delivery of liposome-encapsulated superoxide dismutase and catalase suppress periodontal inflammation in beagles.

BACKGROUND, AIMS: The purpose of this study was to evaluate the influence of oxygen free radical scavengers on periodontal inflammation and healing process. METHOD: Experimental periodontitis was induced by elastic ligatures around premolars (P2, P3, P4) and 1st molars (M1) in the upper and lower jaws of 15 beagle dogs. 9 months after the beginning of the experiment, the ligatures were removed. After 3 weeks of stabilization period, all teeth were supragingivally scaled. The animals were divided into 3 groups of 5 dogs. The 1st group received a liposome-encapsulated superoxide dismutase (SOD), the 2nd group a liposome-encapsulated catalase (CAT) and the 3rd group received both enzymes encapsulated in liposomes. 4 treatment modalities were tested in each group; i.e., supragingival scaling only (1), supragingival scaling and enzymes (2), supra- and sub-gingival scaling and root planing (3) and supra- and sub-gingival scaling and root planing with subgingival application of enzymes (4). Enzymes were delivered subgingivally on a daily basis for a period of 6 weeks. Gingival index (GI), probing depth (PD), clinical attachment level (CAL), radiographic analysis and the histological evaluation were performed. RESULTS: Around the teeth with scaling and root planing followed by the application of SOD, the greatest suppression of gingival inflammation (GI = 1.8 +/- 0.1 before versus GI = 1.2 +/- 0.2 after treatment) (p<0.003), the smallest size of connective tissue infiltrate (5.5 +/- 4.3%) (p<0.01), the greatest reduction of PD (PD= 3.2 +/- 1.0 mm before versus 2.00.7 mm after treatment) (p<0.001), and gain of CAL (CAL=3.0 +/- 1.7 mm before versus CAL=2.4 +/- 1.1 mm after treatment) (p<0.001) were observed. In addition, radiographic analysis showed the greatest alveolar bone apposition in the group of teeth treated with scaling and root planing followed by subgingival application of SOD or both enzymes (p<0.001). CONCLUSION: In conclusion, we demonstrated that scaling and root planing with subgingival application of liposome-encapsulated SOD suppress peridontal inflammation on experimentally induced periodontitis in beagle dogs.

Alveolar Bone Loss↗
PubMed2000

The prevalence of oral mucosal lesions in a population in Ljubljana, Slovenia.

The purpose of the present study was to evaluate the prevalence of oral mucosal lesions and conditions in a population in Ljubljana, capital of Slovenia. A total 1609 subjects represented the study population in the survey about the periodontal treatment needs in a population in Ljubljana, conducted from 1983 to 1987. Ten years later the same 1609 subjects were invited to the second examination. Altogether, 555 (34.5%) of the invited subjects in the age range 25-75 years came for an interview and clinical examination at the Department of Oral Medicine and Periodontology of the Dental Clinic in Ljubljana. Oral mucosal lesions and conditions were evaluated according to the WHO Guide to Epidemiology and Diagnosis of Oral Mucosal Diseases and Conditions. The results showed the presence of one or more mucosal lesions in 61.6% of the population. Fordyce's condition was observed the most frequently (49.7%) followed by: fissured tongue (21.1%), varices (16.2%), history of herpes labialis (16.0%), history of recurrent aphthae (9.7%), denture stomatitis (4.3%), leukoplakia (3.1%), cheek biting (2.7%), lichen planus (2.3%), frictional keratosis (2.2%), geographic tongue (2.2%), geographic and fissured tongue together (1.1%), mucocele (0.9%), smoker's palate (0.5%) and angular chelitis (0.4%). In the population examined, no oral malignancies were observed. Mucosal lesions like whitish lesions, denture related lesions, fissured tongue, varices and mucocele were more prevalent with increasing age. Tobacco-related lesions (leukoplakia and smoker's palate together) were significantly more prevalent among men than among women (P<0.05), while lichen planus, denture stomatitis and herpes labialis occurred more frequently in the female population.

Adult↗
PubMed2000

Superoxide release and superoxide dismutase expression by human gingival fibroblasts.

Oxygen reactive intermediates released from phagocytic cells are important for microbicidal activity, but they may also be harmful to surrounding cells and matrix components at the inflammation site. In different forms of inflammatory periodontal disease, peripheral and crevicular polymorphonuclear leukocytes, as well as mononuclear phagocytes and gingival fibroblasts, are exposed to bacterial cell wall components and cytokines. The aim of this study was to evaluate if some bacterial components and cytokines induce superoxide release and superoxide dismutase (SOD) expression in gingival fibroblasts. Lipopolysaccharide (LPS), streptococcal cell walls (SCW), and formyl-methionyl-leucyl-phenylalanine were found to stimulate O2- release from gingival fibroblasts, which increased when Ca2+ was added. Phorbol myristate acetate, a potent activator of respiratory burst in phagocytes, was found to be a weak stimulator of O2- release in gingival fibroblasts. Of the cytokines tested, tumor necrosis factor (TNF)-alpha was found to activate superoxide release in gingival fibroblasts. Gene expression for manganese superoxide dismutase (MnSOD), but not for copper/zinc superoxide dismutase (CuZnSOD), was demonstrated in fibroblasts exposed to LPS, SCW and TNF-alpha using Northern blot analysis. The production of MnSOD may be protective for these cells. We conclude that bacterial cell wall components and cytokines modulate O2- release by gingival fibroblasts which may contribute to periodontal pathology.

Analysis of Variance↗
PubMed2000

Influence of developer exhaustion on accuracy of quantitative digital subtraction radiography: an in vitro study.

OBJECTIVE: The aim of the study was to evaluate the influence of developer exhaustion on accuracy of quantitative digital subtraction radiography. STUDY DESIGN: Six objects, each incorporating a section of dry human mandible, were radiographed with 4 exposure times. Baseline films were processed in fresh solutions, whereas follow-up films were processed in fresh and in increasingly exhausted solutions (ie, 1, 2, and 3 weeks old). Bone loss and bone gain were computer simulated in 17 regions of interest on baseline radiographs. Area and volume of changes in mineralization were measured in subtracted images, obtained by subtraction of baseline from their corresponding follow-up radiographs. Friedman's 2-way analysis of variance by ranks and Wilcoxon signed-rank test were used for statistical analysis. RESULTS: Because of exhausted developer, bone loss was relatively underestimated from 6.6% to 16.5% (P <.05), whereas bone gain was relatively overestimated from 9.7% to 16.7% (P <.05). CONCLUSIONS: This in vitro study demonstrates that films for quantitative digital subtraction radiography should be processed in fresh developer or error might be introduced.

Alveolar Bone Loss↗
PubMed2000

Proviral HIV-1 DNA in gingival crevicular fluid of HIV-1-infected patients in various stages of HIV disease.

The oral cavity is rarely reported to be a site of human immunodeficiency virus (HIV) transmission, despite detectable virus in saliva and relatively frequent prevalence of periodontal disease in HIV-infected persons yielding increased excretion of mononuclear-cell-enriched gingival fluid. To search for possible sources of HIV in saliva, and using the polymerase chain-reaction technique, we sought the presence and shedding patterns of proviral HIV-1 DNA in gingival crevicular fluid in a group of patients previously determined as HIV-1-seropositive. Periodontal status at the collection sites was monitored by several clinical parameters, including Plaque Index, Gingival Index, probing depth, and clinical attachment loss. Gingival crevicular fluid samples were collected by means of paper points. Proviral HIV-1 DNA was detected in the gingival fluid of 17 out of 35 HIV-1-infected patients. Its detection correlated significantly with higher plasma HIV-1 RNA viral load (p = 0.03) and not with peripheral blood CD4+ cell count, the presence of blood in gingival fluid, or oral lesions. There was a significant correlation between clinical attachment loss at the sites of fluid collection and plasma HIV-1 RNA viral load (p = 0.002), and borderline correlation between the latter and probing depth (p = 0.54) in the group of patients harboring proviral HIV-1 DNA in gingival crevicular fluid. The results of our study suggest that mononuclear cells present in gingival crevicular fluid and harboring proviral HIV-1 DNA could represent a potential source of HIV-1 in the presence or absence of local bleeding, especially in persons with advanced HIV infection and increased loss of clinical attachment.

Adult↗
PubMed1999

The permeability of human cementum in vitro measured by electron paramagnetic resonance.

The structure and permeability of cementum are changed during the course of periodontal disease. In this study, the transport of water-soluble, spin-labelled molecules through cementum was studied by electron paramagnetic resonance (EPR). Cementum samples cut from different parts of the root were classified into four different groups: (A) samples exposed to the oral environment, (B) samples exposed to the periodontal-pocket environment; (C) samples cut from periodontally involved teeth but not exposed to saliva or periodontal pocket and (D) samples from sound young teeth extracted for orthodontic reasons. In order to obtain undamaged cementum, a dentine layer was left on each sample. Two methods were used to measure the diffusion coefficients of spin-labelled molecules in cementum dentine samples. First, the method of one-dimensional EPR imaging (EPRI) was used to evaluate the penetration of spin-labelled molecules into the cementum/dentine structure. Second, the diaphragm-cell method was used to determine the diffusion coefficients of the labelled molecules through the cementum under steady-state conditions. The results indicate that the interface between cementum and dentine is a barrier to diffusion. A set of diffusion (D) and partition (K) coefficients to describe the molecular transport in cementum, barrier and dentine was generated from the experimental data of both methods. For cementum (c), the barrier (b) and dentine (d) these coefficients were: Dc= 10(-8)cm2/s, Db= 10(-10)cm2/s, Dd= 10(-6)cm2/s and K=0.1. For the particular periodontally involved and uninvolved teeth the value of the rate-limiting barrier was DbA= 0.3 +/- 0.03 x 10(-10)cm2/s, DbB= 1 +/-0.3 x 10(-10)cm2/s, DbC= 0.3 +/- 0.03 x 10(-10)cm2/s, DbD= 0.4 +/- 0.05 x 10(-10)cm2/s. The largest diffusion flux across the dental hard tissue was found in the samples that had been exposed to the pocket environment (3.1 +/- 0.2) x 10(-9)cm2/s (p < 0.01), which coincided with the permeability calculated from the data evaluated by EPRI. The transport of the labelled molecules into and through the cementum dentine samples depends on the structure of the dental hard tissues, which changes during the course of periodontal disease. Knowledge of molecular diffusion across the tooth cementum/dentine structure is likely to be important for planning new treatments for periodontal disease.

Adolescent↗
PubMed1998

Crystallite arrangement of hydroxyapatite microcrystals in human tooth cementum as revealed by electron paramagnetic resonance (EPR).

Human dental cementum was analyzed by electron paramagnetic resonance (EPR). The measured EPR powder spectra of gamma-irradiated cementum resembled those of gamma-irradiated enamel. Both spectra were characterized by the same line shapes and g values. The position of the extreme first derivate peaks can be described by g1 = 2.0023 and g2 = 1.9971 +/- 0.0002, and are assignable to the CO3(3-) center. The angular dependence of the cementum EPR spectra indicates a different arrangement of the hydroxyapatite microcrystals compared to that of enamel. A corresponding model of cementum microcrystal alignment has been proposed. The methodology presented can be utilized for studying the mineralization process of root cementum and other mineralized tissues.

Adult↗
PubMed1997

Changes in TGF-beta 1 levels in gingiva, crevicular fluid and serum associated with periodontal inflammation in humans and dogs.

Transforming growth factor-beta (TGF-beta) represents a family of polypeptide growth factors, involved in embryogenesis, inflammation, regulation of immune responses and wound healing. To determine whether TGF-beta contributes to the evolution of periodontal disease, we assayed TGF-beta levels in gingiva and crevicular fluid of patients with gingivitis and periodontitis. In parallel, TGF-beta was quantified in gingival fluid and serum of beagles with experimentally-induced periodontitis. Disease was monitored by several clinical parameters including Plaque Index, Gingival Index, probing depth, and epithelial attachment loss. Gingival tissues were obtained from 9 patients at the time of periodontal surgery, and gingival fluid samples were collected from an additional population of 10 periodontal patients. In 14 beagles, experimental periodontitis was induced and gingival fluids collected 6 months later. Fluid was collected by paper strips and volume measured by Periotron. Additionally, sera was collected before and 9 months after the ligature-induced periodontitis in 7 beagles. The levels of TGF-beta 1 were measured by ELISA. In the patients, a significantly higher concentration of TGF-beta 1 was observed both in the gingival tissues and fluid samples obtained from the sites with deeper periodontal pockets than in the less involved sites. In beagles, TGF-beta 1 levels measured in gingival fluid were elevated in moderate disease, declining in fluid samples obtained from the pockets during more advanced experimental periodontitis. Furthermore, with the progression of experimental periodontitis, a decrease in TGF-beta 1 occurred in the sera of the beagle dogs. These data suggest that TGF-beta 1 may play a rôle in the pathogenesis and diagnosis of periodontal disease, and that its actions can be further explored in an animal model.

Adult↗
PubMed1993

Role of transforming growth factor beta in the pathophysiology of chronic inflammation.

Transforming growth factor beta (TGF-beta), a cytokine identified in acute and chronic inflammatory sites, mediates leukocyte recruitment and activation essential to the development of such lesions. Released by platelets upon aggregation and by leukocytes stimulated with bacterial products or inflammatory mediators, TGF-beta has potent chemotactic activity for blood neutrophils, monocytes, and lymphocytes. By augmenting integrin expression, TGF-beta facilitates leukocyte adhesion to the vessel wall and extracellular matrix at the site of inflammation. Once within the inflammatory site, mononuclear cells are stimulated by TGF-beta to release cytokines important in the network of molecules regulating the host response to microorganisms and immunologic challenge. Thus, bacteria and their products, in addition to directly recruiting and activating leukocytes at sites of infection, indirectly influence these events through the induction of cytokines such as TGF-beta. By antagonizing the activity of TGF-beta with neutralizing antibodies, a causal relationship between this cytokine, inflammation, and pathogenesis has been demonstrated. Administration of anti-TGF-beta to sites of chronic destructive inflammation not only blocked leukocyte recruitment and activation, but also inhibited the subsequent destruction of bone and cartilage characteristics of such lesions.

Bacterial Physiological Phenomena↗
PubMed1993

Cysteine proteinases and inhibitors in inflammation: their role in periodontal disease.

Cellular and molecular events during the development of inflammatory disease are accompanied by the release of host lysosomal cysteine proteinases (CPs) affecting not only degradation of matrix proteins but possibly also antigen processing and chemotaxis of neutrophils. Activity measurements of Cat B and Cat L could not be used as an accurate indicator of disease activity in individual patients, although average values were higher in patients with more advanced periodontal inflammation. In contrast, simultaneous decrease of cystatin C and alpha 2-macroglobulin (alpha 2-M) in inflamed gingiva and gingival fluid, respectively, might be useful diagnostic/prognostic factors. While the total and the free form of alpha 2-M in gingival fluid decreased with the progression of the disease, the complexed alpha 2-M form was hardly detectable. This indicates an increased consumption of this inhibitor by various proteinases and clearance of protease: alpha 2-M complexes by macrophages. Elevated serum levels of alpha 2-M were found in patients with more pronounced disease, suggesting a systemic host response. In addition, high levels of stefin A and moderate levels of kininogen were observed in gingival tissue homogenates. Stefin A was also found to play a role in the inhibition of neutrophil chemotaxis. In addition, other proteinases which are released at inflammatory sites from neutrophils, macrophages, lymphocytes, and/or bacteria may degrade the cystatins, thereby further increasing CP activities. Increased CP activity may inactivate serine protease inhibitors, leading to the so-called "proteolytic burst."

Animals↗
PubMed1991

Inhibitors of reactive oxygen intermediates suppress bacterial cell wall-induced arthritis.

Peritoneal and peripheral blood monocyte-macrophages from inbred Lewis (LEW) rats generate higher levels of reactive oxygen intermediates (ROI) in response to group A streptococcal cell walls (SCW) than do similar populations of cells from histocompatible Fischer rats. This differential sensitivity of the phagocytes to SCW is reflected in differences in susceptibility of the two strains to the development of arthritis in response to SCW. After systemic administration of the SCW, LEW rats develop acute and chronic erosive polyarthritis, whereas the Fischer rats are arthritis resistant. Inasmuch as these data suggested that the SCW-induced release of inflammatory cell products such as ROI might be an important contributory factor in the pathogenesis of arthritis in the LEW rats, the animals were injected with SCW and treated with ROI inhibitors. A single intraarticular injection of superoxide dismutase or catalase significantly reduced the SCW-induced inflammatory response and evolution of erosive arthritis in the treated animals (articular index 3.6 +/- 0.36 for SCW only vs 1.4 +/- 0.3 for SCW + SOD; p less than 0.001; n = 6). These data indicate that ROI play a pivotal role in synovitis and, furthermore, that suppression of these inflammatory mediators modulates both acute and chronic SCW-induced inflammation of the joint.

Animals↗
PubMed1989

Immunochemical quantitation of cysteine proteinase inhibitor cystatin C in inflamed human gingiva.

The amount of the low molecular-weight inhibitor, cystatin C, was determined by the enzyme-linked immunosorbent assay. Gingival tissue samples were obtained during periodontal surgery from 22 patients with different degrees of inflammatory periodontal disease, as indicated by gingival index and probing depth (PD). The concentration of cystatin C was in the range from 0.21 to 3.82 micrograms/g tissue and was significantly decreased (p less than 0.01) in samples taken from sites with increased PD.

Adult↗