Evaluation of method parameters for sound undecalcified dental enamel proteomics using liquid chromatography-mass spectrometry

OBJECTIVE

This study aims to validate a methodology for analyzing undecalcified, sound dental enamel proteomics using Liquid Chromatography-Mass Spectrometry (LC-MS). The study evaluates various parameters, including the impact of dental root coverage on protein contamination, the efficacy of protease inhibitors during enamel sample preparation, repeatability of LC-MS measurements on dental enamel, and statistical analysis. The study also assesses the effectiveness of combined trypsin and semi-trypsin searches in Mascot for obtaining additional protein identification data.

DESIGN

Sound dental enamel was removed using a wet grinding technique, then digested with trypsin and labeled with TMT prior to LC-MS analysis. The resulting proteomes were matched against the Homo sapiens Swissprot Database, with searches in Mascot performed using both trypsin and semitrypsin. Statistical methods were employed to analyze the data.

RESULTS

The study found that covering dental roots with composite during dental enamel microdissection is advisable, while using protease inhibition during microdissection may not be fully supported. The proteomic analyses demonstrated statistical repeatability and reliability, with consistent and reproducible proteomic data obtained from healthy dental enamel. Furthermore, employing both trypsin and semitrypsin searches in Mascot provided additional proteomic information.

CONCLUSIONS

Overall, this study validates a methodology for analyzing undecalcified, sound dental enamel proteomics using LC-MS, and provides insights into various factors that can affect the quality and reliability of proteomic data. These findings have implications for future studies pursuant to understanding the proteomic mechanisms underlying dental enamel formation and other associated processes.

A pilot study comparing optical coherence tomography, radiography, clinical photography, and polarisation microscopy for studies of hypomineralisation disturbances in enamel

Aim

To investigate the use of optical coherence tomography (OCT) as a tool to assess general and localised hypomineralisation defects in the enamel.

Design and Materials

Ten extracted permanent teeth (four teeth with localised hypomineralisation, four teeth with general hypomineralisation, and two healthy controls) were used in this study. In addition, four participants who underwent OCT served as living controls for the extracted teeth.

Methods

The OCT results were compared with clinical photographs, digital radiographs, and polarising microscopy images of tooth sections (considered the gold standard) to determine the method with the most accurate information regarding the extent of enamel disturbances: 1) visibility of enamel disturbance (visible yes/no); if yes, 2) extent of the disturbance in the enamel; and 3) determination of the plausible involvement of the underlying dentin.

Results

OCT was more accurate than digital radiography and visual assessment. OCT could provide information about the extent of localised hypomineralised disturbances in the enamel that was comparable to that with polarisation microscopy of the tooth sections.

Conclusion

Within the limitations of this pilot study, it can be concluded that OCT is suitable for investigating and evaluating localised hypomineralisation disturbances; however, it is less useful in cases with generalised hypomineralisation of the enamel. In addition, OCT complements radiographic examination of enamel; however, more studies are necessary to elucidate the full extent of the use of OCT in case of hypomineralisation.

Factors influencing kidney transplantation rates: a study from the ERA Registry

BACKGROUND

Large international differences exist in kidney transplantation (KT) rates. We aimed to investigate which factors may explain the total, deceased donor, and living donor KT rates over the last decade.

METHODS

KT experts from 39 European countries completed the Kidney Transplantation Rate Survey on measures and barriers and their potential effect on the KT rate in their country. In the analyses, countries were divided into low, middle, and high KT rate countries based on the KT rate at the start of study period in 2010.

RESULTS

Experts from low KT rate countries reported more frequently to have taken measures regarding staff, equipment and facilities to increase total KT rate compared with middle and high KT rate countries. For donor type specific KT, the largest international differences in measures taken were reported for deceased donor KT, with middle and high KT rate countries taking more measures, such as the use of expanded criteria donor kidneys, the presence of transplantation coordinators, and (inter)national exchange of donor kidneys. Once a measure was taken, experts' opinion on its success was similar across the low, middle and high KT rate countries. Experts from low KT rate countries more often reported potential barriers, such as patients' lack of knowledge and distrust in the health care system.

CONCLUSIONS

In particular in low KT rate countries, KT rate might be stimulated by optimizing staff, equipment, and facilities. In addition, all countries may benefit from deceased and living donor specific measures.

How sandblasting on lingual surfaces can be carried out with minimum enamel damage: An in vitro study on human teeth

OBJECTIVE

The aim was to assess the extent of enamel damage sandblasting might cause and to identify a combination of sandblasting durations and MicroEtcher nozzle-tooth surface distance (NTD) resulting in the least enamel damage.

MATERIALS AND METHODS

Lingual surfaces of 30 human teeth were sandblasted with 2 different distances: 1, 2mm and 3 different durations: 1, 2, 3s and photographed using a light microscope. The cavity depth and diameter of the sandblasted teeth were measured on the light microscope's pictures. A pilot study was performed to minimize possible combinations of sandblasting durations and distances. To validate the measurement method, sandblasted teeth were ground cut for comparison. Inter-examiner reliability was assessed with Bland-Altman analysis. Mann-Whitney U-test was used to detect cavity and diameter changes for every sandblasting duration and NTD combination.

RESULTS

From the pilot study sandblasting durations 1,2 and 3s and NTD<2mm were chosen. The cavity diameter of the sandblasted area did not change with increased sandblasting duration nor NTD (P>0.05). The cavity depth of the sandblasted area increased statistically with an increased sandblasting duration (P<0.05) but did not increase with an increase NTD (P>0.05). The 95% limits of inter-examiner agreement were narrow.

CONCLUSION

All distance and duration combinations tested caused enamel damage. Sandblasting duration had greater impact on the cavity depth than the NTD. The blasting duration should, therefore, not exceed 2s and the NTD should be held at maximum 2mm to minimize the risk of unintentional spread.

Ex Vivo Generation of Donor Antigen-Specific Immunomodulatory Cells: A Comparison Study of Anti-CD80/86 mAbs and CTLA4-lg Costimulatory Blockade

Adoptive transfer of alloantigen-specific immunomodulatory cells generated ex vivo with anti-CD80/CD86 mAbs (2D10.4/IT2.2) holds promise for operational tolerance after transplantation. However, good manufacturing practice is required to allow widespread clinical application. Belatacept, a clinically approved cytotoxic T-lymphocyte antigen 4-immunoglobulin that also binds CD80/CD86, could be an alternative agent for 2D10.4/IT2.2. With the goal of generating an optimal cell treatment with clinically approved reagents, we evaluated the donor-specific immunomodulatory effects of belatacept- and 2D10.4/IT2.2-generated immunomodulatory cells. Immunomodulatory cells were generated by coculturing responder human peripheral blood mononuclear cells (PBMCs) (50 × 10⁶ cells) with irradiated donor PBMCs (20 × 10⁶ cells) from eight human leukocyte antigen-mismatched responder–donor pairs in the presence of either 2D10.4/IT2.2 (3 μg/10⁶ cells) or belatacept (40 μg/10⁶ cells). After 14 days of coculture, the frequencies of CD4⁺ T cells, CD8⁺ T cells, and natural killer cells as well as interferon gamma (IFN-γ) production in the 2D10.4/IT2.2- and belatacept-treated groups were lower than those in the control group. The percentage of CD19⁺ B cells was higher in the 2D10.4/IT2.2- and belatacept-treated groups than in the control group. The frequency of CD4⁺CD25⁺CD127^lowFOXP3⁺ T cells increased from 4.1±1.0% (preculture) to 7.1±2.6% and 7.3±2.6% (day 14) in the 2D10.4/IT2.2- and belatacept-treated groups, respectively (p<0.05). Concurrently, delta-2 FOXP3 mRNA expression increased significantly. Compared with cells derived from the no-antibody treated control group, cells generated from both the 2D10.4/IT2.2- and belatacept-treated groups produced lower IFN-γ and higher interleukin-10 levels in response to donor-antigens, as detected by enzyme-linked immunospot. Most importantly, 2D10.4/IT2.2- and belatacept-generated cells effectively impeded the proliferative responses of freshly isolated responder PBMCs against donor-antigens. Our results indicate that belatacept-generated donor-specific immunomodulatory cells possess comparable phenotypes and immunomodulatory efficacies to those generated with 2D10.4/IT2.2. We suggest that belatacept could be used for ex vivo generation of clinical grade alloantigen-specific immunomodulatory cells for tolerance induction after transplantation.

Interproximal grinding (disking) of caries in primary molars, attitudes and the extent utilized in a Swedish County

OBJECTIVE

To assess the occurrence of interproximal grinding as a caries therapy in primary molars, to what degree grinding replaced conventional restorative caries therapy, to what extent anaesthesia was used while grinding and to assess open comments about attitudes about grinding.

MATERIALS AND METHODS

A questionnaire was sent to 108 public dental service clinics with questions concerning the use of grinding as a therapy and alternative to restorative treatment, the use of anaesthesia prior to conventional caries therapy and grinding, respectively. In addition, a content analysis of open comments about grinding was performed.

RESULTS

Grinding had been performed in 96% of the clinics. Two-thirds of the dentists used grinding as an alternative to conventional restorative treatment at some point. Most dentists used anaesthesia prior to restorative therapy. Prior to grinding, the frequency of anaesthesia was lower (median 5.0) than for conventional restorative therapy (median 8.7) (p < .001). The open comment analysis revealed complex reasons for the use of grinding.

CONCLUSIONS

Grinding has been widely practiced in parts of Sweden, is presently a technique employed by a multitude of dentists, and that anaesthesia is used less frequently prior to grinding, in comparison to conventional restorative therapy. Dentist considered grinding as a treatment option in specific situations.

Caries risk profiles in orthodontic patients: A 4-year follow-up study using the Cariogram model in governmental vs. private clinics

OBJECTIVES

To (1) analyze caries-related factors and (2) evaluate caries risk using the Cariogram model for governmental and private orthodontic patients at de-bonding and 4 years after de-bonding.

MATERIALS AND METHODS

Forty orthodontic patients with mean age of 26.4 years were recruited from a governmental (G) group (n = 20) and private (P) group (n = 20) and were examined at de-bonding (T1) and 4 years after de-bonding (T2). The examination included a questionnaire, plaque scoring, caries examination, bitewing radiographs, and assessment of salivary secretion rate, buffering capacity and cariogenic microorganisms. The data were entered into the Cariogram program to illustrate the caries risk profiles.

RESULTS

The chance to avoid new cavities was higher in P-group compared to G-group at T1 (58% and 31%, respectively) (P < 0.01) and T2 (77% and 52%, respectively) (P < 0.001). Plaque index was significantly higher in G-group, and fluoride was used significantly more in P-group at T1 and T2 (P < 0.05). The chance to avoid new cavities was higher at T2 compared to T1 (64% and 44%, respectively) (P < 0.001). Saliva secretion rate and buffer capacity were significantly increased, and the plaque index was significantly decreased at T2 compared to T1 (P < 0.01).

CONCLUSION

According to the Cariogram, orthodontic patients were less likely to avoid new cavities at de-bonding and 4 years after de-bonding in government clinics compared to private clinics, and the caries risk significantly decreased 4 years after orthodontic treatment for all patients, regardless of the location of treatment.

A comparative study of cone beam computed tomography and conventional radiography in diagnosing the extent of root resorptions

Background

Root resorptions are assessed and diagnosed using different radiographical techniques. A comparison of the ability to assess resorptions on two-dimensional (2D) and three-dimensional (3D) radiographs is, hitherto, lacking. The aims of this study were to evaluate the accuracy of 2D (periapical radiographs, PA and panoramic radiograph, PAN) and 3D (cone beam computed tomography, CBCT) radiographic techniques in measuring slanted root resorptions compared to the true resorptions, a histological gold standard, in addition to a comparison of all the radiographic techniques to each other.

Methods

Radiographs (CBCT, PA, and PAN), in addition to histological sections, of extracted deciduous canines from thirty-four patients were analyzed. Linear measurements of the most and least resorbed side of the root, i.e., “slanted” resorptions, were measured using an analyzing software (Facad ®). For classification of slanted root resorptions, a modified Malmgren index was used.

Results

PAN underestimated the root length on both the least and most resorbed side. Small resorptions, i.e., low modified Malmgren scores, were more difficult to record and were only assessed accurately using CBCT. The root resorption scores were underestimated using PA and PAN. In assessment of linear measures, PAN differed significantly from both CBCT and PA.

Conclusions

CBCT is the most accurate technique when measuring and scoring slanted root resorptions.

Impaired Cytotoxicity in Papillon-Lefèvre Syndrome

Papillon-Lefèvre syndrome (PLS), palmoplantar hyperkeratosis with periodontitis, has been genetically characterized. However, suspected associated immune dysfunctions remain elusive. The purpose of this study was to evaluate peripheral blood lymphocyte levels and natural killer (NK) cell cytotoxicity in PLS. Twenty patients and 20 healthy controls were examined. Peripheral blood lymphocytes were analyzed by flow cytometry for surface markers. NK cell cytotoxicity against K562 cells was determined by means of a 51Cr release assay. White blood cell differential and proportions of B-, T-, T-helper, T-suppressor, and NK cells revealed only sporadic borderline variations from control values. In contrast, NK cell cytotoxicity was consistently and severely depressed (32–53% of control values) in all patients. To the best of our knowledge, this newly described impairment of NK cell cytotoxic function is the first consistent immune dysfunction reported in PLS. This suggests that the impaired NK cell cytotoxicity might contribute to the pathogenesis of PLS-associated periodontitis.

Diagnosing the severity of buccal caries lesions in orthodontic patients at de-bonding using digital photographs

OBJECTIVE

The aims of this study were (1) to evaluate the severity of buccal caries lesions according to the International Caries Detection and Assessment System (ICDAS) criteria via scoring buccal caries lesions on digital photographs at the time of de-bonding and (2) to compare this method with clinical examination.

MATERIALS AND METHODS

In total, 89 patients treated with upper and lower fixed appliances were clinically examined immediately after de-bonding by the first author and buccal caries were scored according to the ICDAS-II. Close-up digital photographs were taken of 245 teeth with different buccal caries lesion scores according to the ICDAS-II. Thirteen postgraduate orthodontics students independently scored the buccal caries lesions in the digital photographs using the modified clinical criteria (ICDAS-II). Intra- and inter-examiner reliabilities were evaluated by calculating the weighted kappa. To evaluate the validity of diagnosing the severity of buccal caries lesions using digital photographs compared to clinical examination, Spearman's correlation coefficient was calculated.

RESULTS

Intra-examiner reliability and the reliability between each examiner and the clinical examination showed moderate-to-excellent agreement, with kappa values of 0.52-0.83. Scoring buccal caries lesions via clinical examinations and scoring via photographs were well correlated according to the modified ICDAS-II criteria (Spearman's correlation coefficient, 0.76).

CONCLUSIONS

Thus, scoring buccal caries lesions on digital photographs according to ICDAS-II criteria is a reliable and valid method for assessing the severity of buccal caries lesions.

Diagnosing the severity of buccal caries lesions in governmental and private orthodontic patients at debonding, using the ICDAS-II and the DIAGNOdent Pen

Objectives:

To clinically evaluate the prevalence of buccal caries and white spot lesions (WSLs) at debonding in governmental and private orthodontic patients, using the International Caries Detection and Assessment System (ICDAS-II) and the DIAGNOdent Pen, and to study the correlation between the two methods.

Materials and Methods:

A cross-sectional study was carried out on the nonextracted premolars and anterior teeth of 89 orthodontic patients. They were recruited into two groups based on the treatment center they attended: governmental group (G; n  =  45) and private group (P; n  =  44). Immediately after debonding, the examination of buccal caries and WSLs on premolars and anterior teeth was carried out using the ICDAS-II and the DIAGNOdent Pen. Cross-tabulation was applied to study the correlation between the ICDAS-II index and the DIAGNOdent Pen by calculating the Spearman correlation coefficient.

Results:

The G group showed a significantly higher (P &lt; .0001) prevalence of WSLs and/or buccal caries compared to that of the P group based on evaluation by the two methods. Based on ICDAS-II, 43% of the patients in the P group and 9% in the G group were free from any WSLs. In the G group, 22% of the patients had ≥16 lesions, whereas there were none for the P group. The Spearman correlation coefficient between the two methods was .71.

Conclusions:

The prevalence of caries and/or WSLs at debonding was significantly higher in the G group compared to the P group. The clinical index (ICDAS-II) showed a good correlation with the DIAGNOdent Pen.

Oral immunosuppressive medication for growing pigs in transplantation studies

Immunosuppressive (IS) medication is needed to avoid graft rejection in porcine transplantation models. An ideal IS therapy should have no side-effects, but increased susceptibility to infections, disturbed intestinal microflora and toxic effects on organs and tissues are commonly reported. The aim of the present study was to design an IS protocol with tacrolimus and mycophenolic acid to be used for maintenance therapy in the post-transplant period. An eligible whole blood trough value for tacrolimus was 5–15 μg/L. Conventional specific pathogen-free pigs were fitted with an indwelling catheter under general anaesthesia, and after the acclimatization period three groups were formed: group A ( n= 4) received 0.15 mg/kg body weight (BW) twice daily tacrolimus and 500 mg twice daily mycophenolic acid; group B ( n= 4) received 0.3 mg/kg BW twice daily tacrolimus and 500 mg twice daily mycophenolic acid; group C ( n= 2) did not receive any medication. Daily clinical examinations and analyses of blood concentrations of tacrolimus and glucose were performed. Total and differential white blood cell counts, enzyme activities, bilirubin and electrolyte concentrations were measured every fourth day. At the end of the experiment, the pigs were killed with an overdose of pentobarbital intravenously and a necropsy was performed immediately. All animals seemed to tolerate the IS treatment well. No alterations in their clinical state of health were observed throughout the study and daily weight gain was similar for the three groups. The necropsy did not reveal any pathological findings related to medication. The study showed that 0.25 mg/kg BW twice daily tacrolimus and 500 mg twice daily mycophenolic acid would be an appropriate maintenance dosage for conventional pigs.

Molecular and immunological characterization of Can f 4: a dog dander allergen cross-reactive with a 23 kDa odorant-binding protein in cow dander

BACKGROUND

Dog dander is an important cause of respiratory allergy but its content of allergenic components is still incompletely known. While Can f 1, 2, 3 and 5 have been studied in detail, only fragmentary information is available on the lipocalin Can f 4.

OBJECTIVE

To purify, clone and characterize dog dander allergen Can f 4.

METHODS

Can f 4 was purified from dog dander extract by size exclusion, ion exchange and reverse phase chromatography. A cDNA encoding Can f 4 was cloned and used to produce recombinant Can f 4 in Escherichia coli. A 23 kDa protein from cow dander, displaying cross-reactivity with Can f 4, was purified and identified by amino acid sequencing and mass spectrometry. IgE antibody binding to dog and cow dander extract and to individual dog allergens among 37 dog allergic subjects and 44 pollen allergic controls was studied using ImmunoCAP.

RESULTS

A dog genome segment containing the Can f 4 gene was bioinformatically identified and enabled the cloning of Can f 4 cDNA. Recombinant Can f 4 displayed close immunological and biochemical similarity to purified natural Can f 4 and bound IgE antibodies from 13/37 (35%) sera of dog allergic subjects. Can f 4 reactive sera showed IgE binding to a 23 kDa protein present in cow dander extract, related to a family of odorant-binding proteins. The dog and cow proteins shared 37% sequence identity and their cross-reactivity was demonstrated by IgE inhibition experiments.

CONCLUSION

Recombinant Can f 4 brings the panel of available dog allergens closer to completion and will be important in component-resolved diagnostics in allergy to animal epithelial allergens.

Positron emission tomography in clinical islet transplantation

The fate of islets in clinical transplantation is unclear. To elude on this positron emission tomography combined with computed tomography (PET/CT) was performed for 60 min during islet transplantation in five patients receiving six transplants. A fraction of the islets (23%) were labeled with 18F-fluorodeoxyglucose ([(18)F]FDG) and carefully mixed with unlabeled islets just prior to intraportal transplantation. The peak radioactivity concentration in the liver was found at 19 min after start of islet infusion and corresponded to only 75% of what was expected, indicating that islets are lost during the transplantation procedure. No accumulation of radioactivity was found in the lungs. A nonphysiological peak of C-peptide was found in plasma during and immediately after transplantation in all subjects. Distribution in the liver was heterogeneous with wide variations in location and concentration. Islets found in areas with concentrations of >400 IEQ/cc liver tissue varied between 1% and 32% of the graft in different subjects. No side effects attributed to the PET/CT procedure were found. Clinical outcome in all patients was comparable to that previously observed indicating that the [(18)F]FDG labeling procedure did not harm the islets. The technique has potential to be used to assess approaches to enhance islet survival and engraftment in clinical transplantation.

Rate of reformation of tongue coatings in young adults

BACKGROUND

Reviewing the literature, no study on the rate of regrowth of tongue coatings after tongue cleaning was found. Therefore, the purpose of this study in young adults was to study the rate of reformation of tongue coatings after mechanical removal.

MATERIAL AND METHODS

Thirty-five dental students participated in the present study. Following preparatory study instructions, baseline examinations were carried out followed by 3 days of observation. At baseline, tongue coating scores (prescraping) were obtained followed by tongue scrapings and determination of the wet weights of the coatings. A second tongue coating score was then obtained within 5 min of the first score (immediate post-scraping). The subjects returned for repeated tongue coating scores after 1 and 2 days and for final examination after 3 days, which included both tongue coating scores (prescraping and immediate post-scraping) and determination of the wet weights of the coatings.

RESULTS

Prior to scraping the tongue at day 0 (baseline), mean tongue coating amounted to a surface extension of 33% of the entire dorsum of the tongue. Scraping the tongue reduced the score to 9%. On average, tongue coating scores had returned to baseline levels on day 2. The mean wet weights of tongue scrapings at days 0 and 3 were similar and amounted to 0.09 +/- 0.07 and 0.09 +/- 0.06 g, respectively.

CONCLUSION

If tongue cleaning is to be recommended, the results of this study in dental students indicate that tongue cleaning should be performed on a daily basis.

Elemental composition of normal primary tooth enamel analyzed with XRMA and SIMS

There is an interest to analyze the chemical composition of enamel in teeth from patients with different developmental disorders or syndromes and evaluate possible differences compared to normal composition. For this purpose, it is essential to have reference material. The aim of this study was to, by means of X-ray micro analyses (XRMA) and secondary ion mass spectrometry (SIMS), present concentration gradients for C, O, P and Ca and F, Na, Mg, Cl, K and Sr in normal enamel of primary teeth from healthy individuals. 36 exfoliated primary teeth from 36 healthy children were collected, sectioned, and analyzed in the enamel and dentin with X-ray micro analyses for the content of C, O, P and Ca and F, Na MgCl, K and Sr. This study has supplied reference data for C, O, P and Ca in enamel in primary teeth from healthy subjects. No statistically significant differences in the elemental composition were found between incisors and molars.The ratio Ca/P is in concordance with other studies. Some elements have shown statistically significant differences between different levels of measurement. These results may be used as reference values for research on the chemical composition of enamel and dentin in primary teeth from patients with different conditions and/or syndromes.

Optimising islet engraftment is critical for successful clinical islet transplantation

Clinical islet transplantation is currently being explored as a treatment for persons with type 1 diabetes and hypoglycaemia unawareness. Although 'proof-of-principle' has been established in recent clinical studies, the procedure suffers from low efficacy. At the time of transplantation, the isolated islets are allowed to embolise the liver after injection in the portal vein, a procedure that is unique in the area of transplantation. A novel view on the engraftment of intraportally transplanted islets is presented that could explain the low efficacy of the procedure.

Intramuscular autotransplantation of pancreatic islets in a 7-year-old child: a 2-year follow-up

A 7-year-old girl with severe hereditary pancreatitis underwent total pancreatectomy. A total of 160,000 islet equivalents (6400 islet/kg) were transplanted to the brachioradialis muscle of the right forearm. Her plasma C-peptide level was undetectable after pancreatectomy but increased to 1.37 ng/mL after 17 days; at this time point, her insulin requirement was 0.75 units of insulin/kg/day. At 5- and 27-months, her hemoglobin A1c (HbA1c) and insulin requirements were 4.5 and 5.3% and 0.3 and 0.18 units/kg/day, respectively. Basal and stimulated C-peptide levels were 0.67 +/- 0.07 and 3.36 +/- 1.37 ng/mL, respectively. Stimulated insulin levels were 30% higher in the islet-bearing arm compared to the contralateral arm after glucagon stimulation. After surgery and islet transplantation, the quality of life improved dramatically and she gained 8 kg of weight. In summary, a normal HbA1c, a low insulin requirement and the absence of recurrent hypoglycemia and the gradient of insulin between the arms indicate that the intramuscularly transplanted islets contribute to a long-term clinically significant metabolic control.

Evaluation of tongue coating indices

AIM

The purpose of this study was to determine inter-examiner reproducibility of two modified Winkel tongue coating indices and to study the relationship between each of these two indices and the amount of tongue coating as determined by wet weight of scrapings from the dorsum of the tongue.

MATERIALS AND METHODS

Twenty-five participants were selected for the study from among dental students. The selection was made to assure that a wide range of degrees of tongue coating were represented. Two independent examiners scored the tongue coatings using the two modified Winkel tongue coating indices (mWTCI 1 + 2 and mWTCI 2). After completion of index recordings, tongue scrapings were performed by one of the examiners.

RESULTS

Inter-examiner reproducibility of mWTCI 1 + 2 and mWTCI 2 using Pearson's coefficients of correlation amounted to r = 0.48 and 0.93 respectively. Overall, mWTCI 2 showed higher correlations to wet weight of tongue scrapings than mWTCI 1 + 2.

CONCLUSION

The mWTCI 2 was found to be highly reproducible and also valid as related to wet weight of tongue scrapings. This index would seem suitable for further studies on tongue coatings; effect of tongue cleaning; and rate of reformation of coatings after cleaning.

ABO-Incompatible Kidney Transplantation and Rituximab

We have designed a protocol for ABO-incompatible kidney transplantations based on antigen-specific immunoadsorption rather than plasmapheresis to remove anti-A or anti-B antibodies and with a Prograf/Cellcept/prednisolone protocol using rituximab rather than splenectomy to prevent rebound antibodies. Twelve patients have successfully received transplants with this protocol. The ABO-antibodies were readily removed by the antigen-specific immunoadsorption and maintained at a low-level posttransplantation. There were no side effects. All patients have normal renal transplant function with a follow-up of 1 to 34 months.

Current status of clinical islet transplantation

Islet transplantation is currently being explored as a treatment for patients with type 1 diabetes. At present, the number of patients becoming insulin-independent is rapidly increasing world-wide applying the transplantation protocol originally described by the group in Edmonton. A hallmark in this procedure is repeated infusions of islets obtained from 2 to 4 donors until normoglycemia is achieved. In order to establish islet transplantation as a widely accepted treatment modality, and make tolerance induction regimes applicable, it is essential that the donor:recipient ratio is brought down to 1:1. A conceivable strategy to achieve this goal in clinical islet transplantation is discussed.

Influence of pH and time on organic substance release from a model dental composite: a fluorescence spectrophotometry and gas chromatography/mass spectrometry analysis

In this study we assessed the influence of pH and time on the degradation and elution of organic substances from the composite resin material, Z-100. To accomplish this, fluorescence spectrophotometry was evaluated as an appropriate technique for the identification of six organic substances (methacrylic acid, methyl methacrylate, hydroquinone, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate and 4,4'-isopropylidenediphenol) that were eluted from resin composite material stored for 24 h or 6 months at pH 4.0, 6.0 or 8.0. In addition, complementary analyses (solid-phase microextraction/gas chromatography/mass spectrometry) were carried out to identify and quantify the substances. The main substances leached from the resin composite were methacrylic acid, triethylene glycol dimethacrylate and hydroquinone. It was concluded that fluorescence spectrophotometry seems to be a suitable, non-destructive technique for the qualitative analysis of eluted organic components. Critical combinations of time and pH allowed the elution of several organic substances, predominantly methacrylic acid, triethylene glycol dimethacrylate and hydroquinone, from the model resin composite, Z-100.

Periodontal treatment of patients with Papillon-Lefevre syndrome: a 3-year follow-up

BACKGROUND/AIM

Conventional mechanical periodontal treatment of Papillon-Lefevre syndrome (PLS) has often been reported to fail. This study describes the outcome of a non-surgical periodontal therapy including antimicrobial treatment of nine patients diagnosed with PLS. The patients originate from a total of 15 children and adolescents with PLS for which clinical characteristics are presented.

METHODS

Clinical examination including conventional periodontal measurements. Initial treatment including oral hygiene instruction, scaling and root planing and systemic amoxicillin-metronidazole therapy for 6 weeks. After that the patients were enrolled in a 3-month recall maintenance program. In addition to this mechanical supportive maintenance treatment, tetracycline was prescribed and used continuously for 1.5 years.

RESULTS/CONCLUSION

On five patients who were showing acceptable standard of oral hygiene and also compliance with the antibiotic medication, development of periodontitis on erupting teeth was prevented and disease activity on the previously periodontally involved teeth controlled during a 3-year period. Poor results of treatment were observed for three patients, all siblings. These patients failed to comply with the medication and also failed to improve their oral hygiene.

Phosphate and calcium uptake by rat odontoblast-like MRPC-1 cells concomitant with mineralization

It has been suggested that odontoblasts are instrumental in translocating Ca2+ and inorganic phosphate (Pi) ions during the mineralization of dentin. The aim of this study was to characterize cellular Pi and Ca2+ uptake in the novel rat odontoblast-like cell line mineralizing rat pulpal cell line (MRPC) 1 during mineralization to see if changes in the ion transport activity would occur as the cultures develop and begin forming a mineralized matrix. MRPC-1 cells were cultured in chemically defined medium containing ascorbate and Pi, and cultures were specifically analyzed for cellular P, and Ca2+ uptake activities and expression of type II high-capacity Na+-Pi cotransporters. The odontoblast-like phenotype of the cell line was ascertained by monitoring the expression of collagen type I and dentin phosphopoprotein (DPP). Mineralized nodule formation started at day 9 after confluency and then rapidly increased. Ca2+ uptake by the cells showed a maximum during the end of the proliferative phase (days 5-7). Pi uptake declined to a basal level during proliferation and then was up-regulated simultaneously with the onset of mineralization to a level fourfold of the basal uptake, suggesting an initiating and regulatory role for cellular Pi uptake in mineral formation. This up-regulation coincided with a conspicuously increased glycosylation of NaPi-2a, indicating an activation of this Na+-Pi cotransporter. The study showed that MRPC-1 cells express an odontoblast-like phenotype already at the onset of culture, but that to mineralize the collagenous extracellular matrix (ECM) that formed, a further differentiation involving their ion transporters is necessary.

Antagonistic effects of 24R,25-dihydroxyvitamin D3 and 25-hydroxyvitamin D3 on L-type Ca2+ channels and Na+/Ca2+ exchange in enterocytes from Atlantic cod (Gadus morhua)

There is mounting evidence that vitamin D and its metabolites play important roles in regulating plasma calcium concentrations in teleost fish as in other vertebrates. The aims of the present study were to elucidate the possible cellular target mechanisms for the rapid actions of 24R,25(OH)(2)D(3), 25(OH)D(3) and 1,25(OH)(2)D(3) in Atlantic cod enterocytes at physiological doses, and to establish the concentration and thus the physiological range of circulating 24R,25(OH)(2)D(3), 25(OH)D(3) and 1,25(OH)(2)D(3) in the Atlantic cod. The plasma concentrations of 25(OH)D(3), 1,25(OH)(2)D(3) and 24R,25(OH)(2)D(3) were 15.3 +/- 2.7nM, 125.1 +/- 12.3pM and 10.1 +/- 23.5nM respectively. Exposure of enterocytes to 10mM calcium (Ca(2+)) evoked an increase in intracellular Ca(2+) concentrations ([Ca(2+)](i)). This increase was suppressed by 24R,25(OH)(2)D(3) dose-dependently, with an EC(50) of 4.9nM and a maximal inhibition of 60%. 24R,25(OH)(2)D(3) (20nM) abolished an increase in [Ca(2+)](i) (approximately 252%) in the control enterocytes exposed to 10microM S(-)-BAYK-8644, suggesting that the hormone acts by inhibiting Ca(2+) entry through L-type voltage-gated Ca(2+) channels. Administration of 20nM 24R,25(OH)(2)D(3) to enterocytes in the absence of extracellular Ca(2+) increased [Ca(2+)](i) by approximately 20%, indicating a release of Ca(2+) from intracellular stores. Administration of 25(OH)D(3) (20nM) resulted in a biphasic change in the enterocyte [Ca(2+)](i): within 1--5s, it decreased to 87 +/- 12nM below its mean basal [Ca(2+)](i) (334 +/- 13nM), followed by a rapid recovery of [Ca(2+)](i) to a new level, 10% lower than the initial [Ca(2+)](i). The rapid decrease, the recovery rate and the final [Ca(2+)](i) were all affected dose-dependently by 25(OH)D(3), with EC(50) values of 8.5, 17.0 and 18.9nM respectively. Furthermore, the effects of 25(OH)D(3) were sensitive to sodium (Na(+)), bepridil (10microM) and nifedipine (5 microM), suggesting that 25(OH)D(3) regulates the activity of both basolateral membrane-associated Na(+)/Ca(2+) exchangers and brush border membrane-associated L-type Ca(2+) channels. Administration of 25(OH)D(3) (10nM) to enterocytes in the absence of extracellular Ca(2+) increased [Ca(2+)](i) by approximately 18%, indicating a release of Ca(2+) from intracellular stores. 1,25(OH)(2)D(3) also affected enterocyte [Ca(2+)](i) in a biphasic manner: the rapid decrease, the recovery rate, and the mean final [Ca(2+)](i) were all affected dose-dependently, with EC(50) values of 8.3, 24.5 and 7.7nM respectively. The high EC(50) values for 1,25(OH)(2)D(3) compared with circulating concentrations of 1,25(OH)(2)D(3) (130pM) suggest that this effect is pharmacological, rather than of physiological relevance in enterocyte Ca(2+) homeostasis of the Atlantic cod. It is concluded that 24R,25(OH)(2)D(3) has a physiological role in decreasing intestinal Ca(2+) uptake via inactivation of L-type Ca(2+) channels, whereas the physiological role of 25(OH)D(3) is to increase enterocyte Ca(2+) transport via activation of Na(+)/Ca(2+) exchangers, concurrent with activation of L-type Ca(2+) channels.

Clinical aspects and perspectives in islet xenotransplantation

In 1990-1993, eight diabetic renal transplant patients had porcine fetal islets injected intraportally at Huddinge Hospital in Stockholm. Four of the patients had evidence of xenograft function reflected in the excretion of small amounts of porcine C-peptide. Two patients had the porcine fetal islets placed under the capsule of a simultaneously transplanted kidney. In one of these patients, a graft biopsy specimen taken 3 weeks after transplantation revealed morphologically intact epithelial cells staining positively for insulin and glucagon. The insulin production was in all instances insufficient to affect the patient's insulin requirements. All patients formed specific xenoantibodies (mostly anti-Gal); presumably, most of the xenoislets were destroyed by rejection. On follow-up studies carried out 6-8 years after xenotransplantation, most patients still had higher-than-pretransplant levels of xenoantibodies. There was no evidence of transmission of porcine endogeneous retroviruses to the patients. All patients expressed a positive attitude toward the use of animal tissue for treatment of disease, and none of the patients regretted participating in the trial. Cell transplantation is leading the way at present for clinical xenotransplantation. The finding that complement inhibition protects intraportally injected porcine islets from an injurious incompatibility reaction holds promise for future clinical application. A similar protective effect might be achievable with the use of islets from transgenic pigs expressing human complement receptors.

Intracellular Ca(2+) mobilization and kinase activity during acylated homoserine lactone-dependent quorum sensing in Serratia liquefaciens

Quorum sensing in Gram-negative bacteria involves acylated homoserine lactones (AHLs) and a transcription factor, activated by the AHLs. In this study, a possible involvement of intracellular Ca(2+) as second messenger and/or protein kinase activity during signal transduction is analyzed. When N-hexanoyl-l-homoserine lactone was added to a suspension of Fura-2-loaded Serratia liquefaciens, there was a decline in [Ca(2+)](i), measured as a decrease in the Fura-2 fluorescence ratio. As controls, the addition of the signal molecule N-3-oxohexanoyl-l-homoserine lactone, which is not produced by S. liquefaciens, did not induce changes in [Ca(2+)](i). Using a protein kinase activity assay on AHL-stimulated cells, an increase in kinase activity after N-butanoyl-l-homoserine lactone stimulation of S. liquefaciens cells was detected, whereas the kinase activity induced by N-3-oxohexanoyl-l-homoserine lactone was not statistically significant. The conclusion from this study is that changes in [Ca(2+)](i) are involved in quorum sensing signal transduction in the Gram-negative bacteria S. liquefaciens. We also conclude that kinase activity is induced in S. liquefaciens upon AHL stimulation. We suggest that the transient intracellular [Ca(2+)] changes and kinase activity, activated by the AHL signal, are critical for the quorum-sensing signal transduction.

Junctional proteins and Ca2+ transport in the rat odontoblast-like cell line MRPC-1

A transcellular bulk flow of Ca2+ ions through the odontoblast layer is of central importance during dentinogenesis. For this, specialized mechanisms may exist, which by a concerted action, gate Ca2+ into the proximal end of the cells and extrude the ions towards the mineralization front. To elucidate these mechanisms, an in vitro model would be useful. Mature odontoblasts are, however, post-mitotic cells and cannot be propagated in cell culture. The aim of the present study was, therefore, to characterize the odontoblast-like rat cell line MRPC-1(1) with regard to transcellular Ca2+ transport, barrier function, and intercellular junctions when cultured on membranes in Transwell chambers. The MRPC-1 cells grew as epithelial-like cells in a continuous bilayer separated by a thin collagenous matrix and with intercellular junctional complexes. They exhibited properties of a low-resistance epithelium, maintained a Ca(2+)-dependent diffusion barrier, and exhibited a functional diversity between the two cell layers. MRPC-1 cells expressed ZO-1, occludin, E-, and N-cadherins in addition to alpha-, beta-, gamma- and p120cat catenins, thereby demonstrating some traits in common with, but also differences from, epithelial cells and major differences from fibroblasts. The transcellular Ca2+ flux was inhibitable by nifedipine unidirectionally, giving evidence for an active intracellular Ca2+ transport through voltage-gated channels of the L-type. Similarities with native odontoblasts indicate that MRPC-1 cells may be useful for in vitro studies of transcellular Ca2+ transport mechanisms of importance for the calcification process.

Differences in co-variation of inorganic elements in the bulk and surface of human deciduous enamel: an induction analysis study

This paper demonstrates a method for determination of co-variation between some inorganic elements in the bulk and surface areas of human tooth enamel. The technique is based on a computerised induction analysis of data obtained by secondary ion mass spectrometry (SIMS). When comparing the present data with an earlier study from our laboratory, it became evident that with only a moderate increase in the amount of data for the induction analysis, the results increased very considerably in reliability and precision. The patterns of co-variation between different elements differed between the bulk- and surface enamel. Only Mg expressed a similar pattern. In the bulk enamel the elements Na and P expressed a high degree of co-variation. Similarly, Mg and C expressed a high degree of co-variation. Mg was an element often found to co-vary with bulk enamel elements. In the enamel surface, F and Cl co-varied. In addition, Cl was an element often found to co-vary with other enamel surface elements.

Evidence of a founder effect for four cathepsin C gene mutations in Papillon-Lefèvre syndrome patients

We describe a mutation and haplotype analysis of Papillon-Lefèvre syndrome probands that provides evidence of a founder effect for four separate cathepsin C mutations. A total of 25 different cathepsin C mutations have been reported in 32 families with Papillon-Lefèvre syndrome (PLS) and associated conditions. A characteristic of these findings is the diversity of different cathepsin C mutations that have been identified. To evaluate the generality of cathepsin C mutations, PLS probands representative of five reportedly unrelated Saudi Arabian families were evaluated by mutational and haplotype analyses. Sequence analysis identified two cathepsin C gene mutations: a novel exon 7 G300D mutation was found in the proband from one family, while probands from four families shared a common R272P mutation in exon 6. The R272P mutation has been previously reported in two other non-Saudi families. The presence of the R272P mutation in probands from these four Saudi families makes this the most frequently reported cathepsin C mutation. To distinguish between the presence of a possible founder effect or a mutational hot spot for the R272P mutation, we performed haplotype analysis using six novel DNA polymorphisms that span a 165 kb interval containing the cathepsin C gene. Results of haplotype analysis for genetic polymorphisms within and flanking the cathepsin C gene are consistent with inheritance of the R272P mutation "identical by descent" from a common ancestor in these four Saudi families. Haplotype analysis of multiple PLS probands homozygous for other cathepsin C mutations (W249X, Q286X, and T153I) also supports inheritance of each of these mutations from common ancestors. These data suggest that four of the more frequently reported cathepsin C mutations have been inherited from common ancestors and provide the first direct evidence for a founder effect for cathepsin C gene mutations in PLS. Identification of these six short tandem repeat polymorphisms that span the cathepsin C gene will permit haplotype analyses to determine other founder haplotypes of cathepsin C mutations in additional PLS families.

Osseointegrated implants in a patient with Papillon-Lefèvre syndrome. A 4 1/2-year follow up

BACKGROUND

The Saudi female reported in this study was diagnosed with Papillon-Lefèvre syndrome. She had lost all her teeth, including third molars, at the age of 18 years.

METHOD

She was wearing full dentures for 7 years, before 5 titanium implants were installed in the mandible.

RESULTS

4 1/2 years after the implant installation, the treatment was clinically and radiographically successful. Neither A. actinomycetemcomitans nor P. gingivalis were detected at any of the implants. This very encouraging result does not differ from what is generally reported in edentulous medically healthy patients.

CONCLUSION

The use of implants could considerably enhance future therapeutic options for the severely dentally compromised patients with Papillon-Lefèvre syndrome.

Na+/Ca2+ exchanger isoforms of rat odontoblasts and osteoblasts

In odontoblasts as well as osteoblasts, a number of mechanisms for the inflow and extrusion of Ca2+ have been demonstrated. The entrance of Ca2+ ions into odontoblasts occurs mainly through voltage-gated calcium channels. Extrusion of Ca2+ is found to be an ATP-dependent process and, in addition, Na+/Ca2+-antiports exist, which are provoked by extracellular Na+. The aim of this study was to identify the Na+/Ca2+-antiport isoforms expressed in dentinogenically active rat incisor odontoblasts and to make a comparison with different osteoblastic cells. Using RT-PCR and RNAse protection assay, we demonstrated the expression of three different isoforms, NaCa 3, 7, and 10, of the NCX1-encoded antiport in odontoblasts and osteoblastic cells. When incubated in the presence of Na+, dissected rat incisor odontoblasts as well as the osteoblastic cells extruded Ca2+ ions, as detected by chlorotetracycline and Fura-2 fluorometry, thus supporting a physiological role for the detected isoform expression. Odontoblasts and rat calvarial osteoblasts, as well as osteoblast-like cell lines UMR-106.01 and Saos-2, were shown to exhibit identical phenotypes of Na+/Ca2+-antiport isoform expression, different from the expression patterns of other tissues. The significance of this specific expression pattern is unknown, but there is a possibility that it is in some way related to the unique demands on these cell types to produce mineralized connective tissue.

Damage to porcine islets of Langerhans after exposure to human blood in vitro, or after intraportal transplantation to cynomologus monkeys: protective effects of sCR1 and heparin

BACKGROUND

Porcine islets offer an attractive alternative to human islets in clinical islet transplantation. The preferred method of islet transplantation is intra-portal injection into the liver. We have recently shown, both in vitro with human islets and in vivo with porcine islets, that islets exposed to allogeneic blood trigger an injurious inflammatory reaction characterized by activation of both coagulation and the complement systems. We have now tested whether a similar reaction is triggered when xenogeneic porcine islets are exposed to human blood in vitro and after intraportal transplantation into primates. Furthermore, we investigated the effect of inhibiting the complement and coagulation systems.

METHOD

Islets isolated from adult and fetal porcine pancreas were perfused with fresh human blood in surface heparinized PVC tubings for 5-60 min. Blood cell counts and parameters related to coagulation and the complement system were analyzed, and islets were retrieved after the perifusion was examined by immunohistochemical method. Heparin and soluble complement receptor 1 (sCR1; TP10, 100 microg/ml) were added to the system in some experiments. Furthermore, adult porcine islets were transplanted intraportally into untreated and sCR1- (40 mg/kg BW i.v.) treated cynomolgus monkeys, and plasma insulin concentration was monitored during 60 min after transplantation.

RESULTS

Porcine islets perifused with human blood triggered an immediate inflammatory reaction, characterized by a rapid consumption and activation of platelets, consumption of neutrophils and monocytes, activation of the coagulation and complement systems, and release of large amounts of insulin. Islet morphologic analysis revealed damaged islets embedded in clots and infiltrated with CD11+ leukocytes. C3a and C5b-9 was deposited on the islet surface, but human immunoglobulin was not. Complement inhibition with sCR1 reduced insulin release significantly. Intraportal islet transplantation into untreated cynomolgus monkeys resulted in a marked and rapid increase in plasma insulin concentration indicative of islet damage. Pretreatment of the monkeys with sCR1 resulted in significantly less insulin release than in untreated control monkeys.

CONCLUSION

Exposure of isolated xenogeneic islets of Langerhans to blood, both in vitro and in vivo, resulted in acute islet damage. Complement and platelets seem to have a central role in the reactions described. Strategies to efficiently inhibit these reactions will be crucial for clinical intraportal islet xenotransplantation to be successful.

Discrimination of morphological findings in dentine from osteogenesis imperfecta patients using combinations of polarized light microscopy, microradiography and scanning electron microscopy

OBJECTIVES

The aim of this study was to investigate the morphological appearance of dentine in teeth from individuals with osteogenesis imperfecta type I, III and IV using different histological techniques, and to correlate morphological findings to different types of osteogenesis imperfecta.

SAMPLE AND METHODS

Extracted or exfoliated primary and permanent teeth were collected from 15 patients with the osteogenesis imperfecta diagnoses I, III or IV, with or without the additional diagnosis dentinogenesis imperfecta. Ground and decalcified sections were prepared from the teeth. Histo-morphological studies of the dentine were performed utilizing light and polarized light microscopy, microradiography and scanning electron microscopy.

RESULTS

Characteristic findings were irregular tubules, remnants of capillary inclusions and obliterated pulps. All types of osteogenesis imperfecta exhibited similar types of dentine aberrations, but patients with type III or IV had a higher frequency of aberrations when compared to type I.

CONCLUSIONS

The combination of either polarized light microscopy or micro-radiography, together with scanning electron microscopy, gave the most amount of morphological information from dentine samples. In addition, aberrations in dentine structure were more clearly observable. Light microscopy was not critical for the analyses.

The effect of pH and temperature on the dissociation constant for fura-2 and their effects on [Ca(2+)](i) in enterocytes from a poikilothermic animal, Atlantic cod (Gadus morhua)

In this study, we investigated the validity of the fluorescent probe fura-2 in determinations of intracellular Ca(2+) concentrations ([Ca(2+)](i)), at physiological temperatures, in poikilothermic animals living at low temperatures. The K(d) for fura-2 was found to decrease with increasing temperature (5-37 degrees C) and DeltaH, in the Van't Hoff isochore equation, was determined to be 11.03 kJ/mol, when pH was corrected to 7.2 for all temperatures tested. The absorption maxima (340 nm) and isobestic point (360 nm) for the UV spectra of fura-2 were not affected by temperature. Thus, if pH- and temperature-dependent changes in K(d) are corrected for, fura-2 is a suitable tool for measurements of [Ca(2+)](i) at temperatures of 5-37 degrees C. The present study demonstrates that Atlantic cod enterocytes, acclimated to 37 degrees C, show a lower basal [Ca(2+)](i) (65 +/- 8 nM) compared to enterocytes acclimated to 10 degrees C (161 +/- 6 nM). Furthermore, addition of 10 mM Ca(2+) increases the [Ca(2+)](i) by 526%, when compared to basal [Ca(2+)](i), in cells at 37 degrees C but only by 36%, in cells kept at 10 degrees C. Thus, performing experiments at unphysiological temperatures results in cellular responses that would not be observed under physiological conditions.

Morphology of dental enamel and dentine-enamel junction in osteogenesis imperfecta

OBJECTIVES

The aim of this study was to examine the morphology of primary and permanent human enamel, and the dentine-enamel junction, in individuals with osteogenesis imperfecta (OI) type I, III and IV in undecalcified sections using polarized light microscopy, microradiography and scanning electron microscopy (SEM), and to relate the findings to the type of OI.

SAMPLE AND METHODS

Extracted or exfoliated teeth from 15 patients representing the OI types I, III and IV (12 primary teeth from seven patients, and 11 permanent teeth from eight patients). Ten primary and nine permanent teeth from normal healthy patients served as controls. The teeth were serially cut longitudinally in a bucco-lingual direction and contact microradiographs were made. The sections were examined in polarized light. Sections of primary and permanent teeth were examined by means of SEM.

RESULTS

This study shows that the permanent enamel from patients with OI exhibits few structural changes. No relationships were found between enamel morphology and the types of OI (I, III, IV). Primary enamel appeared to be slightly more irregularly mineralized, especially in cases with the additional diagnosis dentinogenesis imperfecta. The major findings were deviations in association with the dentine-enamel junction, and locally a lower degree of mineralization.

CONCLUSIONS

The mesodermal disease OI might also be manifested in ectodermal enamel, probably because of suboptimal mesenchymal-ectodermal interactions during amelogenesis.

A secondary ion mass spectroscopic study of the elemental composition pattern in rat incisor dental enamel during different stages of ameloblast differentiation

In most earlier studies on the elemental composition pattern of dental enamel, a picture is presented which describes a limited region. In this study, estimates of the incorporation of some critical elements into enamel were correlated with the differentiation stages of the ameloblasts through out the whole tooth. Elemental analyses of rat incisor dental enamel during the secretory, transitional and maturation phases were performed using two different modes of secondary ion mass spectrometry (SIMS). The results were presented as ion images and three-dimensional spatial resolution graphs. In the elemental images of 23Na, 26CN, 35Cl and 39K, counts were detected during the secretory and maturation phases of amelogenesis. Variations were interpreted as resulting from secretion of elements during the secretory phase and resorption during the maturation phase. In line scans the ion yield from enamel during different stages of differentiation of the ameloblasts was analysed. The elements investigated were 12C, 19F, 23Na, 31P, 39K and 77CaCl. As seen in the images, most elements exhibited a higher ion yield during the earlier stages of secretion, and lower yields during the maturation-phase resorption. Cl, together with P, increased during the phases of maturation. In the most apical portions of the teeth, corresponding to a presecretory phase, an inverse pattern was seen for most of the elements. If the surface yield was high at the onset of the secretory phase, the presecretory yields were lower, and vice versa.

Modulation of rat incisor odontoblast plasma membrane-associated Ca2+ with nifedipine

In addition to the Ca2+ portion freely dissociated in the cytosol, another Ca2+ pool is associated with plasma membranes and intracellular organelle membranes. This Ca2+ portion is of importance for regulation of, among other things, the cell cycle, actin-mediated processes, and cell morphology. In the literature, dihydropyridines have been reported to influence this membrane-associated pool of Ca2+ under certain conditions. The aim of this investigation was to study possible modulations of plasma membrane-associated Ca2+ upon treatment with nifedipine in vitro in a Ca2+-transporting cell, the dentin-forming odontoblast. The membrane-associated portion of Ca2+ in dissected dentinogenically active rat incisor odontoblasts was monitored by fluorescence spectrophotometry using chlortetracycline as a probe. In addition, images of chlortetracycline-Ca2+ binding were obtained by fluorescence microscopy. It was found that membrane-associated Ca2+ decreased by the dihydropyridine nifedipine, whereas this Ca2+ pool was unaffected by the cellular polarization state, which was in contrast to cytosolic free Ca2+ as measured by fura-2. The results show that the odontoblast plasma membrane-associated Ca2+-pool can be modulated by nifedipine, thus being dependent on the conformational state of the L-type Ca2+ channels.

Subgingival microbial profile of Papillon-Lefèvre patients assessed by DNA-probes

The prevalence of 18 selected bacterial species was assessed by means of "checkerboard" DNA-DNA hybridisation in a group of 12 Saudi-Arabian adolescents with Papillon-Lefèvre syndrome. A total of 36 tooth sites were investigated. The patients exhibited severe periodontal disease with deep pockets. All 12 patients harboured the putative bacterial pathogens P. intermedia, F. nucleatum, P. micros and S. intermedius while T. denticola, B. forsythus, P. nigrescens, E. corrodens, S. noxia and C. rectus were recovered from 11 patients. P. gingivalis was recovered from 9 patients and 18 sites while corresponding figures for A. actinomycetemcomitans were 8 and 19, respectively. A number of the investigated species (B. forsythus, T. denticola, P. intermedia, C rectus) reached high levels (> or =10(6) cells) in more than 1/2 of the patients. On the other hand, bacteria such as A. actinomycetemcomitans and P. gingivalis were infrequently encountered at high levels in these subgingival samples. In conclusion, the analysis failed to demonstrate a PLS-specific profile of the subgingival infection, since the bacterial composition of the sampled sites closely resembled that characterising deep pockets in adult periodontitis patients.

Ca2+ uptake through voltage-gated L-type Ca2+ channels by polarized enterocytes from Atlantic cod Gadus morhua

The presence and localization of voltage-gated Ca2+ channels of L-type were investigated in intestinal cells of the Atlantic cod. Enterocytes were loaded with the fluorescent Ca2+ probe, fure-2/AM and changes in intracellular Ca2+ concentrations ([Ca2+]i) were measured, in cell suspensions, in the presence of high potassium levels (100 mm), BAY K-8644 (5 microM), nifedipine (5 microM) or omega-conotoxin (1 microM). L-type Ca2+ channels were visualized on intestinal sections using the fluorescent dihydropyridine (-)-STBodipy. Depolarization of the plasma membrane produced a rapid (within 5 sec) and transient (at basal levels after 21 sec) increase in [Ca2+]i. BAY K-8644 increased the [Ca2+]i by 7.2%. Cells in a Ca2+-free buffer increased [Ca2+]i after addition of 10 mm Ca2+, and this increase was abolished by nifedipine in both depolarizing and normal medium but not by omega-conotoxin. Single cell experiments using video microscopy revealed that enterocytes remained polarized several hours after preparation and that the Ca2+ entry and extrusion occurred at specific and different regions of the enterocyte outer membrane. Fluorescent staining of L-type Ca2+ channels in the intestinal mucosa showed the most intense staining at the brushborder membrane. These results demonstrate the presence of voltage gated L-type Ca2+ channels in enterocytes from the Atlantic cod. The channels are mainly located at the apical side of the cells, and there is a polarized uptake of Ca2+ into the enterocytes. This suggests that the L-type Ca2+ channels are involved in the transcellular Ca2+ entry into the enterocytes.

Parathyroid hormone (1-34) receptor-binding and second-messenger response in rat incisor odontoblasts

Even though indirect evidence indicates that PTH exerts an anabolic effect on dentinogenesis, the existence of PTH receptors and any second-messenger response in odontoblasts have not been demonstrated. The aim of this study was to investigate whether rat incisor odontoblasts express PTH receptors, and to identify which second messenger pathway the hormone may activate. Odontoblasts were dissected from rat incisors. Amino-terminal (1-34) fragment rat PTH [rPTH(1-34)] conjugated to fluorescein isothiocyanate visualized receptor sites on the cell surface. Upon incubation of odontoblasts with rPTH(1-34), cAMP formation was increased. However, no fluctuations in intracellular calcium activity were observed upon rPTH(1-34) stimulation when using Fura-2 as a Ca2+ probe. In long-time incubations, stimulation with PTH(1-34) upregulated APase activity. The results demonstrate that rPTH(1-34) evokes an anabolic response in dentinogenically active odontoblasts, and that this may be mediated through the protein kinase A/cAMP pathway, whereas no indications for Ca2+ as a second messenger were evident.

Clinical safety of enamel matrix derivative (EMDOGAIN) in the treatment of periodontal defects

The aim of the present clinical trial was to test tolerability during 2 treatments with EMDOGAIN in a large number of patients. An open, controlled study design in 10 Swedish specialist clinics was chosen, with a test group of 107 patients treated with EMDOGAIN in connection with periodontal surgery at 2 surgical test sites per patient. The procedures were performed 2 to 6 weeks apart on one-rooted teeth with at least 4 mm deep intraosseous lesions. A control group of 33 patients underwent flap surgery without EMDOGAIN at 1 comparable site. In total, 214 test and 33 control surgeries were performed. Serum samples were obtained from test patients for analysis of total and specific antibody levels. 10 of the patients had samples taken before and after the first surgery, 56 other samples were taken after one treatment with EMDOGAIN, and 63 after 2 treatments. None of the samples, not even from allergy-prone patients after 2 treatments, indicated deviations from established baseline ranges. This indicates that the immunogenic potential of EMDOGAIN is extremely low when applied in conjunction with periodontal surgery. Comparison between the test and control groups demonstrated the same type and frequency of postsurgical experiences, i.e., reactions caused by the surgical procedure itself. Clinical probing and radiographic evaluation was performed at baseline and 8 months postsurgery. About half of the patients (44 test and 21 control) were also evaluated after 3 years. There was a significant difference between the test and control results at 8 months postsurgery, and this difference had increased further at the 3 year follow-up. The 2.5-3 mm increase in attachment and bone level after treatment with EMDOGAIN was of the same magnitude as seen in the studies with split-mouth design aiming for test of effectiveness of EMDOGAIN.

Pulp calcifications in traumatized primary incisors. A morphological and inductive analysis study

The purpose of this study was to investigate histopathological changes in primary teeth following trauma, and to look for possible correlations between the morphology of pulpal calcification and clinical findings. The material consisted of 123 primary teeth from 98 Danish children aged 9-108 months (mean age 33.5 +/- 19.7 months) at the time of injury. The specimens were analyzed by means of light and scanning and transmission electron microscopy. Data from the clinical investigation and from predetermined ranked parameters from the histological analysis were processed in a computerized inductive analysis program. The results, describing patterns of co-variation, are presented as a decision tree. The most common diagnosis was intrusion luxation (54%). In 41% of all teeth, the degree of obliteration was less than 1/4 of the pulpal lumen. In most cases (79%), no denticles were visible. When present, 80% of the denticles had a bone-like appearance. Tissues occluding the pulpal lumen were either dentin-like (49%), bone-like (19%), or fibrotic (9%). It could be concluded that these varying responses could not be correlated with explicit clinical diagnoses. However, in certain combinations, histological parameters could be correlated to clinical findings.

Voltage-gated calcium channels and nonvoltage-gated calcium uptake pathways in the rat incisor odontoblast plasma membrane

Odontoblasts participate actively in the transport and accumulation of Ca2+ ions to the mineralization front during dentinogenesis. These cells are known to carry membrane-bound ATP-driven pumps and Na+/Ca2+ antiports for Ca2+ extrusion, but little is known about Ca2+ influx mechanisms into these cells. It has been shown that the administration of Ca2+ channel blockers in vivo strongly impairs Ca2+ uptake in the mineral phase during dentinogenesis in the rat; the present in vitro study is aimed at further elucidating odontoblast Ca2+ uptake mechanisms. Dissected rat incisor odontoblasts exhibited a pronounced fluorescence when incubated with a fluorescently-labeled (STBodipy) dihydropyridine, which is specific for voltage-gated Ca2+ channels of the L-type, and this binding was competitively abolished by nifedipine. As assayed by fluorescence spectrometry, odontoblast Ca2+ uptake was enhanced by the agonistic dihydropyridine BAYK-8644 (5 micro;M) as well as by plasma membrane depolarization in a high K+ (120 mM) medium. The Ca2+ uptake after depolarization was impaired by nifedipine (5 micro;M). When treated with the Ca2+-ATPase inhibitor cyclopiazonic acid (CPA; 10 micro;M), a nonvoltage-gated uptake of 45Ca2+ was identified. This uptake was not influenced by nifedipine (20 micro;M) but was impaired by lanthanum ions (200 micro;M). A nonvoltage-gated uptake of Mn2+ into CPA-treated cells could be traced using the fura-2 quenching technique. This CPA-induced Ca2+ flux was not caused by an alteration of the plasma membrane potential, as assayed with di-8-ANEPPS. The results demonstrate that Ca2+ flux into dentinogenically active odontoblasts occurs through voltage-gated Ca2+ channels of the L-type and by nonvoltage-gated, agonist-sensitive Ca2+ uptake pathways.

Saliva composition in children and young adults with Papillon-Lefèvre syndrome

The aim of the present study was to evaluate the salivary secretion rate and composition in a group of 16 children and young adults (6-27 years) with Papillon-Lefèvre Syndrome (PLS), and to compare the findings with a group (n = 16) of healthy controls. Unstimulated and stimulated whole saliva was collected at least 2 h after meals and the secretion rate determined. The stimulated saliva was assessed for buffer capacity, total protein, peroxidase and hexosamine, while the unstimulated samples were evaluated for total protein, lysozyme, thiocyanate, lactoferrin and salivary IgA. Both the unstimulated (p < 0.01) and stimulated (p < 0.05) saliva secretion rates were significantly lower among the PLS patients compared with the controls. Furthermore salivary buffer capacity was significantly (p < 0.01) lower in the PLS patients. The total protein content in saliva was comparatively high in the study group, while the concentrations of immunoglobulins and non-immunoglobulins were within normal ranges. When calculating the output of the assessed antimicrobial factors, the mean peroxidase level in stimulated whole saliva was found to be significantly (p < 0.01) lower in the PLS patients than in the healthy controls. In conclusion, the present study indicates an impaired water secretion and a somewhat altered saliva gland function in children and young adults with PLS.