Reduction in the rate of inositol 1,4,5-trisphosphate synthesis in rat parotid acini by lithium

Stimulation of muscarinic cholinergic receptors on rat parotid acinar cells causes a rapid production of inositol phosphates, with the key metabolic event being the breakdown of phosphatidylinositol 4,5-bisphosphate into inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) and diacylglycerol. Here a high-performance liquid chromatographic technique was used to measure the effects of intracellular lithium ions on the amount of various inositol phosphates produced. When acini were stimulated maximally with acetylcholine (ACh), the sum of all inositol phosphates produced followed a monoexponential function with a production rate constant for Ins(1,4,5)P3 of 0.07 +/- 0.01 solidus/sec. The presence of 23 mM LiCl intracellularly reduced the production rate constant of Ins(1,4,5)P3 induced by ACh to 0.03 +/- 0.01 solidus/sec, resulting in a decrease in the Ins(1,4,5)P3 production as well as in the magnitude of the rise in the intracellular free Ca2+ concentration. The lithium ion (Li+) did not affect the rate of conversion of Ins(1,4,5)P3 to either inositol 1,4-bisphosphate or inositol 1,3,4,5-tetrakisphosphate. The rate of the inositol phosphate production after the addition of the Ca2+ ionophore ionomycin was unaffected by intracellular Li+ (23 mM), which implies that the action of Li+ was at the muscarinic cholinergic receptor, on G-protein or on the interactions between G-proteins and phospholipase C. Thus, in the early events after receptor stimulation with ACh, Li+ causes a reduction in the concentration of the cellular messengers Ins(1,4,5)P3 and Ca2+.     

Orofacial pain emerging as a dental specialty

The emerging field of orofacial pain was considered by the American Dental Association for full status as a new dental specialty. While the recognition of orofacial pain as a specialty was denied, the American Academy of Orofacial Pain plans to continue its efforts. Many recent advances in the neuroscience of orofacial pain have led to treatments that provide significant relief for patients with chronic orofacial pain disorders. However, access to this care has been limited, leaving many patients to suffer. Dentists are generally supportive of the efforts to develop oral pain treatment into a specialty because the field will provide benefits for both dentists and their patients. A recent survey of 805 individuals who reported having a persistent pain disorder revealed that more than four out of 10 people have yet to find adequate relief, saying their pain is out of control--despite having the pain for more than five years and switching doctors at least once. "This survey suggests that there are millions of people living with severe uncontrolled pain," says Russell Portenoy, MD, president of the American Pain Society. "This is a great tragedy. Although not everyone can be helped, it is likely that most of these patients could benefit if provided with state-of-the-art therapies and improved access to pain specialists when needed." Development of the field of orofacial pain into a dental specialty has been moved primarily by the fact that historically, patients with complex chronic orofacial pain disorders have not been treated well by any discipline of healthcare. Recent studies of chronic orofacial pain patients have found that these patients have a higher number of previous clinicians and have endured many years with pain prior to seeing an orofacial pain dentist (see Figure 1). Complex pain patients and the clinicians who see them are often confused about who they should consult for relief of the pain. Treatment for those patients within the existing structure of dental or medical specialties has been inadequate, with millions of patients left suffering. Insurers are also confused with regard to reimbursement and may make decisions to exclude treatment for orofacial pain disorders under both dental and medical policies. However, dentistry has taken a leading role in healthcare to address the national problem of developing the field of orofacial pain into a dental specialty. A study of dentists and dental specialists has shown that there is a recognized need and broad support for developing this field into a specialty.     

Genetic variation in the recognition of Porphyromonas gingivalis antigens in mice

T-cell cytokine profiles, anti-Porphyromonas gingivalis antibodies and Western blot analysis of antibody responses were examined in BALB/c, CBA/CaH, C57BL6 and DBA/2J mice immunized intraperitoneally with different doses of P. gingivalis outer membrane antigens. Splenic CD4 and CD8 cells were examined for intracytoplasmic interleukin (IL)-4, interferon (IFN)-gamma and IL-10 by FACS analysis and levels of anti-P. gingivalis antibodies in the serum samples determined by enzyme-linked immunosorbent assay. Western blot analysis was performed on the sera from mice immunized with 100 microg of P. gingivalis antigens. The four strains of mice demonstrated varying degrees of T-cell immunity, although the T-cell cytokine profiles exhibited by each strain were not affected by different immunizing doses. While BALB/c and DBA/2J mice exhibited responses that peaked at immunizing doses of 100-200 microg of P. gingivalis antigens, CBA/CaH and C57BL6 demonstrated weak T-cell responsiveness compared with control mice. Like the T-cell responses, serum antibody levels were not dose dependent. DBA/2J exhibited the lowest levels of anti-P. gingivalis antibodies followed by BALB/c with CBA/CaH and C57BL6 mice demonstrating the highest levels. Western blot analysis showed that there were differences in reactivity between the strains to a group of 13 antigens ranging in molecular weight from 15 to 43 kDa. Antibody responses to a number of these bands in BALB/c mice were of low density, whereas CBA/CaH and C57BL6 mice demonstrated high-density bands and DBA/2J mice showed medium to high responses. In conclusion, different immunizing doses of P. gingivalis outer membrane antigens had little effect on the T-cell cytokine responses and serum anti-P. gingivalis antibody levels. Western blot analysis, however, indicated that the four strains of mice exhibited different reactivity to some lower-molecular-weight antigens. Future studies are required to determine the significance of these differences, which may affect the outcome of P. gingivalis infection.     

Validation of DIAGNOdent for quantification of smooth-surface caries: an in vitro study

The aims were 1) to validate a laser-based device, KaVo DIAGNOdent, for quantification of caries lesions on smooth surfaces, using histopathologic and microradiographic analyses as the gold standard, and 2) to test inter- and intra-observer agreements. We also investigated the influence on DIAGNOdent readings of the storage medium used for extracted teeth. Two observers measured independently the tooth surfaces of 40 extracted premolars that had been stored in thymol-saturated saline. After subsequent storage in neutral-buffered formalin for 14 days they were re-measured. The teeth were then sectioned for histopathologic and microradiographic analysis. The Spearman rank correlation coefficients between lesion depth and DIAGNOdent readings were 0.78-0.83 and 0.85 for teeth stored in thymol-saturated saline and formalin, respectively. Inter- and intra-observer agreements were 0.94 and 0.95 when the teeth were stored in thymol-saturated saline. The DIAGNOdent reading was almost 1.5 times higher for teeth stored in formalin than for those stored in thymol saline. The Spearman rank correlation coefficient between mineral loss in enamel (deltaZ) and DIAGNOdent readings ranged from 0.64 to 0.68. It was concluded that DIAGNOdent may be helpful for assessing smooth-surface caries, but the cut-off points need to be assessed under clinical conditions. The increase in fluorescence associated with storage of teeth in formalin warrants further investigation.     

Periodontal infection and preterm birth: results of a prospective study

BACKGROUND: Previous studies have suggested that chronic periodontal infection may be associated with preterm births. The authors conducted a prospective study to test for this association. METHODS: A total of 1,313 pregnant women were recruited from the Perinatal Emphasis Research Center at the University of Alabama at Birmingham. Complete periodontal, medical and behavioral assessments were made between 21 and 24 weeks gestation. After delivery, medical records were consulted to determine each infant's gestational age at birth. From these data, the authors calculated relationships between periodontal disease and preterm birth, while adjusting for smoking, parity (the state or fact of having born offspring), race and maternal age. Results were expressed as odds ratios and 95 percent confidence intervals, or CIs. RESULTS: Patients with severe or generalized periodontal disease had adjusted odds ratios (95 percent CI) of 4.45 (2.16-9.18) for preterm delivery (that is, before 37 weeks gestational age). The adjusted odds ratio increased with increasing prematurity to 5.28 (2.05-13.60) before 35 weeks' gestational age and to 7.07 (1.70-27.4) before 32 weeks' gestational age. CONCLUSIONS: The authors' data show an association between the presence of periodontitis at 21 to 24 weeks' gestation and subsequent preterm birth. Further studies are needed to determine whether periodontitis is the cause. CLINICAL IMPLICATIONS: While this large prospective study has shown a significant association between preterm birth and periodontitis at 21 to 24 weeks' gestation, neither it nor other studies to date were designed to determine whether treatment of periodontitis will reduce the risk of preterm birth. Pending an answer to this important question, it remains appropriate to advise expectant mothers about the importance of good oral health.     

Conscious sedation experiences in graduate pediatric dentistry programs

PURPOSE: Conscious sedation is a behavior modification adjunct taught in all postgraduate pediatric dental residency programs. It has been a decade since the last survey was done specifically related to didactic and clinical aspects of conscious sedation in postgraduate pediatric dental programs. The aim of the study was to determine the clinical and didactic experiences associated with conscious sedation in these programs and to compare some of the findings to those collected a decade ago. METHODS: A 31-item survey similar to that of a decade ago was constructed and sent to all pediatric dentistry program directors of accredited postgraduate and residency programs in the United States. The items covered several didactics including didactic topics, sedative agents, monitoring, and emergency policy among others. A follow-up mailing was done involving those who had not responded 6 weeks following the initial mailing. RESULTS: Fifty-four of 58 (93%) program directors returned the 31-item survey. The following are highlighted findings. Conscious sedation among residency programs was achieved most commonly with a combination of sedative agents used with N2O. Midazolam was more popular than chloral hydrate. The oral route was the predominant route of administration. More lecture hours were spent on conscious sedation than 10 years ago. The pre-cordial stethoscope, pulse oximeter, and blood pressure cuff were the most commonly used monitors. Sedative agent and anticipated depth of sedation were the factors most often considered in choosing monitors used during the sedation of a patient. The capnograph was being used more frequently than it was 10 years ago. Programs did not report an increase in sedation emergencies but practiced emergency drills more often and had increased numbers of individuals certified in Advanced Cardiac Life Support (ACLS) or Pediatric Advanced Life Support (PALS). The percent of the total patient population which required sedation is about 1-20%, with most directors reporting an increase in the numbers of sedations done in the past few years. CONCLUSIONS: While many factors remained unchanged or slightly modified when compared to the survey done a decade ago, the results of this study suggest that there has been significant changes in several key factors including the most frequently used sedative (i.e., midazolam) and increased preparation in the area of emergency preparedness.     

Total IgA and Porphyromonas gingivalis-reactive IgA in the saliva of patients with generalised early-onset periodontitis

Generalised early-onset periodontitis (GEOP) is characterized by acute inflammatory bursts, resulting in rapid destruction of the periodontal apparatus in young adults. An impaired host defense seems to play an important role as etiological factor of periodontitis, especially in the development of GEOP. As the gram-negative Porphyromonas gingivalis has been identified as one of the causative anaerobic bacteria, the humoral immune response to this micro-organism is of particular interest in patients with GEOP. To evaluate the local immune status, we measured total and P. gingivalis-reactive salivary IgA in GEOP patients and in age- and gender-matched periodontally normal controls. We found a significantly lower concentration and secretion rate of total salivary IgA in the GEOP group. Although no differences were detected in the concentration or secretion of P. gingivalis-reactive IgA between groups, the specific fraction of P. gingivalis-reactive IgA of the total IgA was significantly higher in the GEOP group. These findings indicate an inhibition of total secretory IgA in GEOP, while the P. gingivalis-reactive humoral immune system in saliva is, however, activated. P. gingivalis seems to selectively activate IgA lymphocyte clones and induces a switch in the fraction of specific IgA.     

Concurrence of replicative senescence and elevated expression of p16(INK4A) with subculture-induced but not calcium-induced differentiation in normal human oral keratinocytes

Primary normal human oral keratinocytes (NHOKs) undergo differentiation in the presence of calcium concentrations higher than 0.15 mM in vitro, which is useful in investigating the mechanisms involved in the differentiation of epithelial cells. Serial subculture of NHOKs to the postmitotic stage also induces terminal differentiation. However, the detailed mechanisms of both differentiation processes remain substantially unknown. To investigate the molecular differences in these processes, NHOKs were induced to differentiate by exposure to 1.2 mM of calcium and by serial subculture to the postmitotic stage. To study whether the cells were induced to differentiate and to undergo replicative senescence, the amount of cellular involucrin and the expression of senescence-associated beta-galactosidase (SA-beta-gal) were measured respectively. The expression of replicative senescence-associated genes and the activity of telomerase from the differentiated cells were also determined. Both calcium treatment and serial subculture to the postmitotic stage notably elevated the cellular involucrin. The percentage of SA-beta-gal-positive cells was significantly elevated by the continued subculture, but such changes were not observed in keratinocytes exposed to calcium. The concentration of cellular p16(INK4A) protein was progressively increased by the continued subculture but was not changed by calcium treatment. On the other hand, the concentrations of cellular p53 were similar in both differentiation processes. However, telomerase activity was lost in NHOKs that had undergone differentiation by both calcium treatment and serial subculture. The results indicate that calcium-induced differentiation of NHOKs has similar characteristics to their serial subculture-induced differentiation, but that the differentiation processes are not identical, because calcium-induced differentiation does not concur with either replicative senescence or the gradually increased concentration of p16(INK4A).     

Antibody responses against Porphyromonas gingivalis infection in patients with early-onset periodontitis

BACKGROUND, AIMS: The aim of this study was to evaluate antibody responses against Porphyromonas gingivalis (P. gingivalis) infection in early-onset periodontitis (EOP) patients to elucidate further the host-parasite interactions in the pathogenesis of EOP. METHOD: 16 P. gingivalis-infected EOP and 20 adult periodontitis (AP) patients, and 18 periodontally healthy subjects (HS) participated in this study. Serum immunoglobulin G (IgG) antibody levels and avidities against extracted P. gingivalis whole cells were measured. The components of P. gingivalis outer membrane antigens (OMA) reacting to patients' sera were analysed from the molecular weights by Western blotting. Serum antibody levels against P. gingivalis lipopolysaccharide (LPS) were also measured. The ability of the patients' sera to block interleukin-1beta (IL-1beta) production by human mononuclear cells in response to P. gingivalis LPS was examined. RESULTS: Antibody levels were positively correlated with antibody avidities in both EOP and AP patients (r=0.91, r=0.72, p<0.0005, respectively), while not significantly so in HS (r=0.09). There was variability in the antigen recognition of P. gingivalis OMA in EOP and AP patients. Smear and 53-kDa protein were more frequently recognized by sera of EOP and AP patients rather than that of HS (p<0.05). The smear was partly diminished by absorption with P. gingivalis LPS, indicating the smear antigen was partly composed of LPS. There was high correlation between antibody levels against P. gingivalis whole-cell extracts and LPS in EOP and AP patients (r=0.81, p=0.0002, r=0.87, p<0.0001, respectively), while not significant in HS (r=0.22). The sera of EOP and AP patients with high IgG titre to P. gingivalis LPS blocked IL-1beta production more effectively than that of the patients with low IgG titre to P. gingivalis LPS. CONCLUSIONS: These results indicate that EOP patients' antibody response against P. gingivalis infection does not differ significantly from that of AP patients. The person-to-person heterogeneous antibody production against P. gingivalis LPS could contribute to our understanding of the relationship between the defensive ability of EOP patients and their chronic infection with this pathogen.     

Crown dilaceration of a first premolar caused by extraction of its deciduous predecessor: a case report

This report describes a rare case of crown dilaceration of the mandibular first premolar caused by trauma during extraction of the precedent primary first molar. The mandibular first primary molar had been extracted at the age of 4 years 7 months. Compared to the pre-operative radiograph, the post-operative film showed that the direction of the first premolar tooth germ had changed, suggesting that crown dilaceration had been induced by the surgical procedures during tooth extraction. From radiographic examinations, the premolar was considered to have erupted spontaneously.