Histological and radiological outcome after horizontal guided bone regeneration with bovine bone mineral alone or in combination with bone in edentulous atrophic maxilla: A randomized controlled trial.

OBJECTIVE: To assess the radiological and histological outcome after horizontal guided bone regeneration (GBR) with deproteinized bovine bone mineral (DBBM) alone or in combination with particulate autogenous bone (PAB). MATERIALS AND METHODS: Eighteen edentulous patients with an alveolar ridge of ≤4 mm were included in this split-mouth randomized controlled trial. Horizontal GBR with a graft composition of 100% DBBM (100:0) on one side and 90% DBBM and 10% PAB (90:10) on the other side were conducted in all patients. Cone beam computed tomography (CBCT) was obtained preoperatively, immediately postoperative, and after 10 months of healing. Width and volumetric changes in the alveolar process were measured on CBCT. Implants were placed after 10 months of graft healing where biopsies were obtained for histomorphometrical evaluation. RESULTS: The gained widths were 4.9 (±2.4) mm (100:0) and 4.5 (±2.0) mm (90:10) at 3 mm from the top of the crest, and 5.6 (±1.3) mm (100:0) and 4.6 (±2.1) mm (90:10) at 6 mm from the top of the crest. The mean volumetric reductions were 32.8% (±23.8) (100:0) and 38.2% (±23.2) (90:10). Histomorphometry revealed that mean percentages of bone were 50.8% (±10.7) (100:0) and 46.4% (±11.3) (90:10), DBBM were 31.6% (±12.6) (100:0) and 35.4% (±14.8) (90:10), and non-mineralized tissue were 17.6% (±11.7; 100:0) and 18.2% (±18.2) (90:10). No significant differences were evident between in any evaluated parameters. CONCLUSIONS: There were no additional effects of adding PAB to DBBM regarding bone formation, width changes, or volumetric changes after 10 months of graft healing.

Accuracy of the Swedish quality registry for caries and periodontal diseases (SKaPa) - evaluation in 6- and 12-year-olds in the region of Värmland, Sweden.

OBJECTIVES: This study evaluates the agreement of data on dental caries between electronic dental records and data retrieved from the national SKaPa-registry (Swedish Quality Registry for caries and periodontal disease), with special reference to e/M in deft/DMFT. METHODS: In a random sample of 500 6- and 12-year-old children having received dental care in 2014 in the county region of Värmland, Sweden, the diagnostic accuracy of data in electronic dental records with corresponding data obtained from the SKaPa-registry was compared by using Cohen's Kappa and Intraclass correlation coefficient (ICC). RESULTS: For dft/DFT the Kappa was 0.95, and ICC 0.98 (total population). For deft/DMFT in the total population the Kappa was 0.80 and ICC 0.96. For 6-year-olds (deft) the Kappa was 0.89 and ICC 0.99 and for 12-year-olds (DMFT) the Kappa was 0.70, and ICC 0.83. The corresponding figures for Kappa and ICC when excluding individuals without caries (deft/DMFT = 0) were: Total population 0.63 and 0.94; 6-year-olds 0.79 and 0.99; 12-year-olds 0.42 and 0.68. CONCLUSION: Agreement between data in the dental records and SKaPa was very high for dft/DFT confirming that transfer from the dental records to the SKaPa-registry is safe and correct. As the accuracy of deft/DMFT was considerably lower than for dft/DFT we advise against using deft/DMFT data from SKaPa for research purposes at this point.

Prevalence of ongoing or previous SARS-CoV-2 infection among dental personnel - the Swedish experience.

CONCLUSIONS: The seroprevalence of SARS-CoV-2 infection was approximately similar to that in healthcare personnel, and approximately equal compared to that in the general population. MATERIALS AND METHODS: We carried out an observational cohort study from March to June 2020, including 341 employees randomly selected from Public Dental Service in the County of Stockholm. The primary outcome variable was the prevalence of SARS-CoV-2 RNA and/or antibodies against SARS-CoV-2. Throat samples were analysed for SARS-CoV-2 RNA. Venous blood was collected to detect antibodies against SARS-CoV-2 using the Luminex analysis tool (immunoassay) and ELISA. Logistic regression analysis was used to compare the independent groups and calculate the unadjusted odds ratio. OBJECTIVE: To investigate whether personnel in a public dental clinic had a higher frequency of ongoing or previous severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection than hospital healthcare workers or the general public in Stockholm during weeks 23-25 in 2020. RESULTS: The mean age of the participants was 50.1 years, and 11.7% were male. The prevalence of SARS-CoV-2 RNA and/or antibodies against SARS-CoV-2 was 12.0% (95% confidence interval 8.8-16.0). Among them, 82.5% reported symptoms and 85.4% were on sick-leave between March and June 2020.

Dental implant procedures contribution to the total antibiotic use in Swedish dentistry. A register-based study.

OBJECTIVE: To study the influence of demographic and organizational factors to antibiotic utilization in dental implant surgery in Sweden. MATERIAL AND METHODS: Descriptive statistics regarding antibiotic prescription between 2009 and 2019 was retrieved from two national registers, the Swedish Prescribed Drug Register and the Dental Health register, both administered by the National Board of Health and Welfare. RESULTS: During the years 2009-2019 a significant decrease of the proportion of prescriptions of systemic antibiotics in conjunction with implant surgical procedures occurred in all patient groups where the most common procedure was the insertion of a single implant. The proportion of dental visits when implant surgical treatment was performed which resulted in a prescription of antibiotics decreased significantly from 1/3 to approximately 1/5. However, comparing Public and Private dental care providers, the reduction was significantly greater in Public dental care. Patients with low level of education in urban regions, treated in Private dental clinics were more likely to receive antibiotics in conjunction to implant surgery compared to other groups. Phenoxymethylpenicillin is the most widely used substance in conjunction with implant surgery. CONCLUSION: There is still room for improvement in reduction of antibiotic prescriptions in conjunction to implant surgical procedures in Sweden.

Swedish quality registry for caries and periodontal diseases (SKaPa): validation of data on dental caries in 6- and 12-year-old children.

BACKGROUND: The Swedish Quality Registry for caries and periodontal disease (SKaPa) automatically collects data on caries and periodontitis from patients' electronic dental records. Provided the data entries are reliable and accurate, the registry has potential value as a data source for registry-based research. The aim of this study was to evaluate the reliability and accuracy of the SKaPa registry information on dental caries in 6- and 12-year-old children. METHOD: This diagnostic accuracy study compared dental caries data registered at an examination with dental health status registered in the patient's electronic dental records, and with corresponding data retrieved from the SKaPa registry. Clinical examinations of 170 6- and 12-year-old children were undertaken by one of the researchers in conjunction with the children's regular annual dental examinations where the number of teeth were registered, and dental caries was diagnosed using ICDAS II. Teeth with fillings were defined as filled and were added to the ICDAS II score and subsequently dft/DFT was calculated for each individual. Cohen's Kappa, the intraclass correlation coefficient (ICC), and sensitivity and specificity were calculated to test the agreement of the 'decayed and filled teeth' in deciduous and permanent teeth (dft/DFT) from the three sources. RESULTS: Cohen's Kappa of the dft/DFT-values was calculated to 0.79 between the researcher and the patient record, to 0.95 between patient dental record and SKaPa, and to 0.76 between the researcher and SKaPa. Intraclass correlation coefficient (ICC) was calculated to 0.96 between the researcher and the patient journal, to 0.99 between the patient dental record vs. SKaPa, and to 0.95 between the researcher and SKaPa. CONCLUSION: The SKaPa registry information demonstrated satisfactory reliability and accuracy on dental caries in 6- and 12-year-old children and is a reliable source for registry-based research. Trial registration The study was registered in Clinical Trials ( www.ClinicalTrials.gov , NCT03039010).

Radiographic changes in height and volume after lateral GBR procedures with different ratios of deproteinized bovine bone mineral and autogenous bone at different time points. An experimental study.

OBJECTIVE: Estimate changes in augmentation height and volume after lateral guided bone regeneration (GBR) augmentation with different ratios of deproteinized bovine bone mineral (DBBM) and particulate autogenous bone (PAB) and autogenous bone block (ABB), at different time points. MATERIAL AND METHODS: Twenty-four minipigs were randomly allocated into three healing periods. Lateral augmentation in 96 sites with standardized quantity of graft material was performed with different ratios of DBBM and PAB (50:50, 75:25, and 100:0) and ABB in combination with DBBM, covered by a collagen membrane. Changes in augmentation height and volume were assessed on CT volumes acquired 10, 20, and 30 weeks after surgery. RESULTS: Reduction in bone augmentation height was as follows: 50:50-1.7 mm (-33.1%), 75:25-1.8 mm (-37.8%), 100:0-1.7 mm (-35.8%), and ABB - 0.2 mm (-3.7%), after 30 weeks. The augmentation height was significantly better preserved with ABB compared to 50:50, 75:25, and 100:0, while no significant difference was present among particulate grafts. No significant difference in volumetric reduction was found among 50:50, 75:25, 100:0 and ABB after 30 weeks, while 100:0 presented significant less reduction compared to 50:50, 75:25 and ABB after 10 and 20 weeks. CONCLUSIONS: Augmentation height following GBR was better preserved with ABB covered with DBBM. Addition of PAB to DBBM did not affect the changes in height of the graft. The volumetric stability seems to be comparable for ABB covered by DBBM and all particulate grafts after 30 weeks. However, DBBM alone revealed significant less volume reduction in the early healing phase.

Effect of governmental strategies on antibiotic prescription in dentistry.

Objective: To study the effect of governmental strategies, to constitute and publish recommendations on antibiotic usage in dentistry, on the antibiotic consumption.Material and methods: Descriptive statistics regarding antibiotic prescription between 2009 and 2017 was retrieved from two national registers, the Swedish Prescribed Drug Register and the Dental Health register, both administered by the National Board of Health and Welfare. Age standardization was applied to alleviate the comparison between gender, different regions and years.Results: The number of dispatched prescriptions of antibiotics from dentists was reduced with 31% during the study period. 10% of the visits to a dentist generated an antibiotic prescription corresponding to 7% of the total number of antibiotic prescriptions. A decline in prescription was observed after publication of national recommendations for antibiotics prophylaxis in 2012 and antibiotic treatment in 2014. Unexplained geographical and gender differences in the rates of prescription were seen.Conclusions: Data indicates a correlation between introduction of governmental strategies to reduce antibiotic usage and declining antibiotic prescription. Although a marked reduction in prescription was observed, the results indicate that there is further potential for improvement of antibiotic stewardship in odontology.

The Swedish dental health register - validation study of remaining and intact teeth.

BACKGROUND: Sweden has a long tradition of nationwide registers enabling population-based research of high quality and validity. We aimed to describe the content and validity of reported number of remaining and intact teeth in the Swedish Dental Health Register and report some descriptive data on dental health care utilization. METHODS: The Swedish Dental Health Register was initiated in July 1st 2008 and contains individual data on dental health care to the whole adult population of Sweden. The dental care given freely to children and young adults is not included. Descriptive data on remaining, intact teeth and dental health care utilization is presented by proportion of the population stratified by sex and age. We conducted a validation study, by manual review of randomly sampled 1500 dental health visits records, to assess reported number of teeth to the register with what was actually recorded in the dental health care record (gold standard), analyzed by positive predictive value (PPV) and Bland-Altman plots. RESULTS: Of the Swedish adult population 2014, 2.6 million (69%) men and 2.9 million (76%) women had at least one visit to a dentist during a two-year period 2013 to 2014. More than half of the population up to age 64 have all remaining teeth (28 teeth or more). Of the 1500 requested dental records 1131 (75%) were received. The positive predictive value for patients reported to the register as having at least 1 tooth up to 31 intact teeth was 91.5% (95% confidence interval 89.0-93.5, 567 manually reviewed to be correct out of 620 reported). CONCLUSIONS: For patients coded as having less than 32 intact teeth but not being edentulous the reported number of remaining and intact teeth is to a very high degree correct. However, the correctness for those coded as edentulous or having 32 remaining intact teeth is low and varies substantially by age.

Caries treatment in Swedish adults: effectiveness, costs and equity. A 4-year follow-up study of data from the Swedish national dental health register.

At a national level, planning and management of dental services should be based on assess- ments of equity, effectiveness and costs. In Sweden, data for the adult population are now acces- sible through The Swedish dental health register, at The National Board of Health and Welfare. This study, on two large cohorts of Swedish adults, is based on longitudinal follow-up data, retrieved from the Swedish dental health register.The aims were twofold: to assess frequencies and costs of fillings and crowns, including subsequent repair; secondly to study the relationship between preventive and restorative dental treatment.The Swedish dental health register pro- vides data on the adult population which offers a new perspective on public health aspects of management of dental care at the national level. A longitudinal, prospective study model was used to follow-up two large cohorts for over four years. In the first cohort, data on 1,088,923 adult patients were analysed with reference to provision of single crowns and fillings over a period of 42 -48 months.The second cohort comprised 1,703,147 adult patients: the data were analysed with reference to preventive interventions over a period of 48 - 54 months. Frequencies of distribution of dental care by age group showed that the cohorts were representative for the whole patient group.With respect to equity, the average number of dentist appointments per i,ooo inhabitants for all 21 regions of Sweden was 140 to 160, despite major variations in geographic conditions and population densities. With respect to effectiveness, about 76% of the teeth with index interven- tions required no additional intervention over four consecutive years of follow-up. For the remain- ing 24% of the teeth 77% had only one additional intervention. When differences of case-mix were taken into account, the costs of repairs to earlier ihterventions were basically similar, regardless of age-group.There were no gender differences. However, there were pronounced differences, of up to three intact teeth, among patients from different regions of Sweden. Follow-up of effects of caries prevention showed no gender differences. However, costs for reparative interventions increased with higher costs for preventive treatment. Moreover, the longer the interval between preventive interventions, the lower the costs for reparative interventions.The national dental health register is a potentially valuable source of data for dental research. In this study, longitu- dinal registry data on restorative and preventive treatment were retrieved and analysed, with reference to efficacy, costs and equity. The results have potential application in improving mana- gement of public dental health.

Narcolepsy patients have antibodies that stain distinct cell populations in rat brain and influence sleep patterns.

Narcolepsy is a chronic sleep disorder, likely with an autoimmune component. During 2009 and 2010, a link between A(H1N1)pdm09 Pandemrix vaccination and onset of narcolepsy was suggested in Scandinavia. In this study, we searched for autoantibodies related to narcolepsy using a neuroanatomical array: rat brain sections were processed for immunohistochemistry/double labeling using patient sera/cerebrospinal fluid as primary antibodies. Sera from 89 narcoleptic patients, 52 patients with other sleep-related disorders (OSRDs), and 137 healthy controls were examined. Three distinct patterns of immunoreactivity were of particular interest: pattern A, hypothalamic melanin-concentrating hormone and proopiomelanocortin but not hypocretin/orexin neurons; pattern B, GABAergic cortical interneurons; and pattern C, mainly globus pallidus neurons. Altogether, 24 of 89 (27%) narcoleptics exhibited pattern A or B or C. None of the patterns were exclusive for narcolepsy but were also detected in the OSRD group at significantly lower numbers. Also, some healthy controls exhibited these patterns. The antigen of pattern A autoantibodies was identified as the common C-terminal epitope of neuropeptide glutamic acid-isoleucine/α-melanocyte-stimulating hormone (NEI/αMSH) peptides. Passive transfer experiments on rat showed significant effects of pattern A human IgGs on rapid eye movement and slow-wave sleep time parameters in the inactive phase and EEG θ-power in the active phase. We suggest that NEI/αMSH autoantibodies may interfere with the fine regulation of sleep, contributing to the complex pathogenesis of narcolepsy and OSRDs. Also, patterns B and C are potentially interesting, because recent data suggest a relevance of those brain regions/neuron populations in the regulation of sleep/arousal.

GPR37 protein trafficking to the plasma membrane regulated by prosaposin and GM1 gangliosides promotes cell viability.

The subcellular distribution of the G protein-coupled receptor GPR37 affects cell viability and is implicated in the pathogenesis of parkinsonism. Intracellular accumulation and aggregation of GPR37 cause cell death, whereas GPR37 located in the plasma membrane provides cell protection. We define here a pathway through which the recently identified natural ligand, prosaposin, promotes plasma membrane association of GPR37. Immunoabsorption of extracellular prosaposin reduced GPR37(tGFP) surface density and decreased cell viability in catecholaminergic N2a cells. We found that GPR37(tGFP) partitioned in GM1 ganglioside-containing lipid rafts in the plasma membrane of live cells. This partitioning required extracellular prosaposin and was disrupted by lipid raft perturbation using methyl-ß-cyclodextrin or cholesterol oxidase. Moreover, complex formation between GPR37(tGFP) and the GM1 marker cholera toxin was observed in the plasma membrane. These data show functional association between GPR37, prosaposin, and GM1 in the plasma membrane. These results thus tie together the three previously defined components of the cellular response to insult. Our findings identify a mechanism through which the receptor's natural ligand and GM1 may protect against toxic intracellular GPR37 aggregates observed in parkinsonism.

Label-free quantitative mass spectrometry reveals novel pathways involved in LL-37 expression.

Antimicrobial peptides are important for a healthy host-microbe homeostasis. In infections characterized by low levels of the human cathelicidin, LL-37, induction of its expression increases clearance of pathogens. Our aim was to discover signaling pathways and compounds capable of affecting the expression of LL-37. We recently observed a synergistic induction of LL-37 expression by stimulating the colonic epithelial cell-line HT-29 with lactose and phenylbutyrate (PBA). Here, we studied regulatory circuits mediating this synergism in HT-29 cells stimulated with lactose (60 g/l) and PBA (2 mM) for 24 h by using mass spectrometry and pathway analyses. Selected pathways were evaluated for their involvement in LL-37 regulation in a CAMP gene-luciferase reporter system. Three pathways were examined in detail: thyroid hormone receptor and retinoid X receptor (TR/RXR) activation, eicosanoid signaling and steroid biosynthesis. Induced expression of LL-37 was observed upon stimulation with triiodothyronine (T3, 2.5 nM-1 µM for 3-30 h) and thyroxine (T4, 2.5-10 nM for 24 h). Furthermore, the synergism of lactose and PBA was reduced in cells coincubated with inhibitors of phospholipase A2, cyclooxygenase 2 or HMG-CoA reductase. Based on these results, we conclude that proteomics and pathway analyses are valuable tools for dissecting the regulatory networks involved in LL-37 expression.

Boosting innate immunity: development and validation of a cell-based screening assay to identify LL-37 inducers.

Innate immunity, the front line of our defence against pathogens, relies, to a great extent, on the production of antimicrobial peptides (AMPs). These peptides exhibit antimicrobial activity and immunomodulatory properties. In humans, AMPs include the defensins (α- and ß-families) and the cathelicidin, LL-37. Bacterial resistance against antibiotics is a growing concern, and novel antimicrobial strategies are needed urgently. Hence, the concept of strengthening immune defences against infectious microbes by inducing AMP expression may represent novel or complementary pharmaceutical interventions in the treatment or prevention of infections. We have developed and validated a robust cell-based reporter assay for LL-37 expression, which serves as a marker for a healthy epithelial barrier. This reporter assay can be a powerful tool for high-throughput screenings. We first employed our assay to screen a panel of histone deacetylase inhibitors and derivatives, and then the Prestwick Chemical Library of Food and Drug Administration-approved compounds. After hit confirmation and independent validation in the parental cell line we identified five novel inducers of LL-37. This reporter assay will help to identify novel drug candidates for the treatment and prevention of infections. Importantly, the pattern of hits obtained may suggest cellular pathways and key mediators involved in the regulation of AMP expression.

Lactose in human breast milk an inducer of innate immunity with implications for a role in intestinal homeostasis.

Postpartum, infants have not yet established a fully functional adaptive immune system and are at risk of acquiring infections. Hence, newborns are dependent on the innate immune system with its antimicrobial peptides (AMPs) and proteins expressed at epithelial surfaces. Several factors in breast milk are known to confer immune protection, but which the decisive factors are and through which manner they work is unknown. Here, we isolated an AMP-inducing factor from human milk and identified it by electrospray mass spectrometry and NMR to be lactose. It induces the gene (CAMP) that encodes the only human cathelicidin LL-37 in colonic epithelial cells in a dose- and time-dependent manner. The induction was suppressed by two different p38 antagonists, indicating an effect via the p38-dependent pathway. Lactose also induced CAMP in the colonic epithelial cell line T84 and in THP-1 monocytes and macrophages. It further exhibited a synergistic effect with butyrate and phenylbutyrate on CAMP induction. Together, these results suggest an additional function of lactose in innate immunity by upregulating gastrointestinal AMPs that may lead to protection of the neonatal gut against pathogens and regulation of the microbiota of the infant.

Antimicrobial peptides important in innate immunity.

Antimicrobial peptides are present in all walks of life, from plants to animals, and they are considered to be endogenous antibiotics. In general, antimicrobial peptides are determinants of the composition of the microbiota and they function to fend off microbes and prevent infections. Antimicrobial peptides eliminate micro-organisms through disruption of their cell membranes. Their importance in human immunity, and in health as well as disease, has only recently been appreciated. The present review provides an introduction to the field of antimicrobial peptides in general and discusses two of the major classes of mammalian antimicrobial peptides: the defensins and the cathelicidins. The review focuses on their structures, their main modes of action and their regulation.

Impaired release of antimicrobial peptides into nasal fluid of hyper-IgE and CVID patients.

BACKGROUND: Patients with primary immunodeficiency (PID) often suffer from frequent respiratory tract infections. Despite standard treatment with IgG-substitution and antibiotics many patients do not improve significantly. Therefore, we hypothesized that additional immune deficits may be present among these patients. OBJECTIVE: To investigate if PID patients exhibit impaired production of antimicrobial peptides (AMPs) in nasal fluid and a possible link between AMP-expression and Th17-cells. METHODS: Nasal fluid, nasopharyngeal swabs and peripheral blood mononuclear cells (PBMCs) were collected from patients and healthy controls. AMP levels were measured in nasal fluid by Western blotting. Nasal swabs were cultured for bacteria. PBMCs were stimulated with antigen and the supernatants were assessed for IL-17A release by ELISA. RESULTS: In healthy controls and most patients, AMP levels in nasal fluid were increased in response to pathogenic bacteria. However, this increase was absent in patients with common variable immunodeficiency (CVID) and Hyper-IgE syndrome (HIES), despite the presence of pathogenic bacteria. Furthermore, stimulation of PBMCs revealed that both HIES and CVID patients exhibited an impaired production of IL-17A. CONCLUSION: CVID and HIES patients appear to have a dysregulated AMP response to pathogenic bacteria in the upper respiratory tract, which could be linked to an aberrant Th17 cell response.

Specificity in killing pathogens is mediated by distinct repertoires of human neutrophil peptides.

Neutrophil-derived antimicrobial peptides and proteins (AMPs) play an important role in the defense against microbes. Absence of defense is illustrated by neutropenic patients with frequent bacterial and fungal infections. However, the specificity of the antimicrobial effects has not been adequately described. We set out to determine the specific antimicrobial pattern of polypeptides in neutrophils (polymorphonuclear leukocytes, PMNs) against 4 potential human pathogens: Moraxella catarrhalis, Staphylococcus aureus, Haemophilus influenzae and Candida albicans. Protein extracts of human PMNs were separated using high-performance liquid chromatography and fractions were assayed for antimicrobial activity. Fractions displaying antimicrobial activity were separated on SDS-PAGE and characterized using MALDI-MS. Depletion experiments were utilized to determine the contribution of each AMP to the antimicrobial effect. Among the identified AMPs, α-defensins 1-3, azurocidin, LL-37, lysozyme, calprotectin and lactotransferrin were studied in detail. We found a divergent pattern of killing, that is, certain peptides and proteins exhibited selective activity against specific pathogens, while others displayed a broader antimicrobial activity. α-Defensins, LL-37 and calprotectin were active against all species, while lactotransferrin exclusively inhibited growth of S. aureus. Conversely, azurocidin was active against all species except S. aureus. Our observations may shed light on bacterial resistance to AMPs and on the elimination of specific bacterial communities on mucosal surfaces.

PU.1 and bacterial metabolites regulate the human gene CAMP encoding antimicrobial peptide LL-37 in colon epithelial cells.

Mammalian antimicrobial peptides contribute to the protective barrier against microbes at epithelial surfaces. This study focuses on the promoter of the human CAMP gene, encoding the antimicrobial peptide LL-37, and induction of the gene in the colonic epithelial cell line HT-29. CAMP promoter segments were inserted in front of a luciferase reporter in order to identify regulatory regions. A transcription promoting region was identified and the transcription factor PU.1 of the Ets family was recruited to this region as shown by ChIP analysis. This ties PU.1 to the regulation of human innate epithelial defences for the first time. In addition, the conserved second intron was found to exert a transcription enhancing effect in cooperation with the 3' end of the proximal promoter, and the importance of two upstream AUG codons was examined. Moreover, we here demonstrate that lithocholic acid enhances CAMP transcription, and does so additively with butyrate. Thus, a crosstalk between bacteria and host epithelia of the gut could be partially mediated via these two bacterial products to obtain gut homeostasis.

Chimeric small subunits influence catalysis without causing global conformational changes in the crystal structure of ribulose-1,5-bisphosphate carboxylase/oxygenase.

Comparison of subunit sequences and X-ray crystal structures of ribulose-1,5-bisphosphate carboxylase/oxygenase indicates that the loop between beta-strands A and B of the small subunit is one of the most variable regions of the holoenzyme. In prokaryotes and nongreen algae, the loop contains 10 residues. In land plants and green algae, the loop is comprised of approximately 22 and 28 residues, respectively. Previous studies indicated that the longer betaA-betaB loop was required for the assembly of cyanobacterial small subunits with plant large subunits in isolated chloroplasts. In the present study, chimeric small subunits were constructed by replacing the loop of the green alga Chlamydomonas reinhardtii with the sequences of Synechococcus or spinach. When these engineered genes were transformed into a Chlamydomonas mutant that lacks small-subunit genes, photosynthesis-competent colonies were recovered, indicating that loop size is not essential for holoenzyme assembly. Whereas the Synechococcus loop causes decreases in carboxylation V(max), K(m)(O(2)), and CO(2)/O(2) specificity, the spinach loop causes complementary decreases in carboxylation V(max), K(m)(O(2)), and K(m)(CO(2)) without a change in specificity. X-ray crystal structures of the engineered proteins reveal remarkable similarity between the introduced betaA-betaB loops and the respective loops in the Synechococcus and spinach enzymes. The side chains of several large-subunit residues are altered in regions previously shown by directed mutagenesis to influence CO(2)/O(2) specificity. Differences in the catalytic properties of divergent Rubisco enzymes may arise from differences in the small-subunit betaA-betaB loop. This loop may be a worthwhile target for genetic engineering aimed at improving photosynthetic CO(2) fixation.

Do intact collagen fibers increase dentin bond strength?

The purpose of the present study was to evaluate surface morphology and shear bond strength of All Bond 2 bonded to dentin surfaces, that were treated progressively to remove collagen fibers. For the study of surface morphology, fifteen teeth were divided in to five groups. Dentin surfaces in groups 1-4 were etched either with 24% EDTA for 30 seconds or 32% phosphoric acid for 15 seconds with and without subsequent treatment with 10% NaOCl for 60 seconds. Group 5 received no treatment and served as control. Evaluation was performed using scanning electron microscopy. Thirty teeth were used for the shear bond strength test. Two experimental surfaces were prepared on each tooth and cylindrical copper matrixes were attached to the surfaces. Experimental surfaces were divided into four groups and treated in the same way as group 1-4 in the morphology part of the study. Dentin was bonded with All Bond 2, after which a flowable composite was inserted and light cured. Shear strength test was performed at a crosshead speed of 1 mm/minute until the composite debonded. Results showed that etching followed by treatment with NaOCl removed all collagen fibers from the dentin surfaces, while treatment with EDTA alone denuded the fiber structures. Shear strength was significantly decreased when surfaces were treated with NaOCl. The highest shear strength values were obtained in the EDTA etched group. The results from the present study indicate that exposed dentin associated collagen fibers increases adhesion of All Bond 2 to dentin.